Extraction 2018

A whole new group of non-ferrousNon-ferrous pyrometallurgical processes with the ability to utilize tonnage oxygen and capture sulphur dioxide were developed and commercialized over the period 1940s–1980s. Many of these earlier process developments were undertaken with limited knowledge of the process chemistry and influence of key process variables; in many cases, piloting helped provide much new physico-chemical data, but gaps remained. The second generation versions of these technologies of today provide all the primary copperCopper, nickelNickel and leadLead produced worldwide by pyro-metallurgical smeltingSmelting. Further, process development has continued and a new generation of copperCopper and lead smeltingLead smeltingSmelting technologies have also been developed in China since the 1990s. The older reverberatory and blast furnaces have been progressively replaced by the newer technologies—a good example being the introduction in 1992 of the copperCopper IsaSmelt technology at the Mt. Isa smelter in Australia where the former fluid bed roaster and reverberatory furnaces were replaced by a single new smeltingSmelting unit, together with an acid plant for sulphur dioxide collection. The development of these new technologies was made possible by investment in fundamental and applied research. The lesson for the future is, in order to sustain these improvements, continued investment in research and development capability is required—to do otherwise is to risk obsolescence and lack of competiveness in the world market. Dr. Peter HayesPeter hayes at The University of Queensland is one of the many researchers and process engineers who have contributed to the fundamental understanding of metallurgical processes over this period of rapid change in technologies. The present paper briefly outlines some of the many contributions Peter HayesPeter hayes has made to the understanding of kinetics, mechanisms and phase equilibriaPhase equilibria in metallurgical systems, and metallurgical process development.

PyrometallurgyPyrometallurgy is an important sector of modern industrial society actively participating in solving current environmental, economic, materials scarcity and other challenges. Recent advances in analytical methods, experimentalExperimental techniques, thermodynamic, phase equilibriaPhase equilibria and process modelling tools provide new opportunities to increase the productivityProductivity of pyrometallurgical reactors, the treatment of complex feeds and metal recoveries. Fundamental theoretical models can now be used to make a significant next step towards the development and implementation of computerised models describing real industrial processes—Virtual Reactors, and computer-aided smart-decision-making systems that may be called Pyro-GPS by analogy to GPS; these developments can facilitate knowledge-based improvement and optimisation strategies. The implementation of these improvements require ongoing collaboration between researchers, industry and government.

It is now 35 years since the organization of the first sulfideSulfidesmeltingSmelting conference in 1983. Since then, the smeltingSmelting base metals industry has experienced several changes driven by the necessity to improve economic, operational and environmental performances and resource efficiencyEfficiency and meet the increasing market demand for metals. In this continuously challenging environmentEnvironment, it is relevant to recognize which are the main challenges that the industry will face in the coming years and critically address our preparedness to respond to them. This analysis have to consider not only the effort required from the fundamental research and technology aspects but also how these pillars interact with the drivers behind the base metals industry. This paper discusses some relevant aspects required to continue developing the base metal industry focusing on copperCopper. Aspects such as the need to supporting the generation of fundamental metallurgical knowledge, acquisition and proper use of data with advanced analytics methods, technological innovation to develop sustainable process flowsheetFlowsheet are discussed with emphasis on efforts conducted by Aurubis.

The world continues to change and with it the supply of mineralsMinerals and metals, the location of centres of production of primary metal and the increasing levels of metals and materials recyclingRecycling. New technologies are being developed to meet the ongoing search by industry for lower costs, cleaner production and new markets. To keep abreast with these changes, and to utilise fully, the potential benefits of these technical advances, the industry will need a professional workforce having different knowledge, skills and professional attributes than in the previous millennium. What are these skills and attributes? How to best attract and develop the metallurgists of the future, and provide for the ongoing educational and research needs of the industry?

Japanese non-ferrous industry introduced large-scale smelting plants along seashores for overseas concentrates with increasing demand of metals around 1970s. Although serious environmental pollution became obvious, with economic growth, the industry got rid of pollution by installing new processes and improving operation technologies. At present, over 99.8% of sulfur input to smelters is fixed as stable compounds. Through those decades Japan had steep rises of oil prices, sudden change of exchange rate, and inadequate treating charges, we were faced to consider the closure of smelters. The industry has survived by increasing productivity, saving energy and reducing manpower. Furthermore the industry made great effort to recycle valued metals from scraps and wastes for the resources-recycling society. Academic research also contributes to support these individual technologies. Thus the industry has fostered world-acclaimed technologies in terms of efficiency and energy conservation. This paper presents technology development and environmentally-benign sulfide smelting processes.

Boliden Harjavalta has operated a flash smelter for nickelNickel sulphide concentrates in Finland since late 1959. The original nickelNickelflash smeltingFlash smelting process was modified in 1995 to a novel nickel matteNickel mattesmeltingSmelting (DON) with semi-low ironIron where the batchwise operated converting became obsolete. Since that, the process has been applied to multiple chemically variable nickelNickel sulphide concentrates with high environmental performance. In this paper, the status of the current smelter operationsSmelter operations is described together with the recent modernizations of the nickelNickelflash smeltingFlash smeltingfurnaceFurnace and the slagSlag cleaning furnaces.

After 40 years of operation with the original design, Pan Pacific CopperCopper determined it was necessary to rebuild the Saganoseki Flash Flash smeltingSmeltingSmeltingFurnaceFurnace to continue safe operation. The original design employed a rigid steelSteel frame, which, through hearth growth, led to severe distortion of the frame. Contributing to the continued growth of the hearth were thermal cycles that occurred during the government mandated annual shutdowns. HatchHatch designed a unique sprung bound, pivoting binding frame to maximize crucible size within the existing furnaceFurnace footprint, while integrating the PPCPpc designed coolingCooling jackets. The bound system maintains tight brick joints, while the new conductive hearth design with integrated bottom coolingCooling produces a protective freeze layer to accommodate higher furnaceFurnace throughput. Minimization of furnaceFurnace downtime for the rebuild was achieved through effective construction planning, highly trained contractors, and through an efficient start-up and ramp-up to full production.

Recent advances in analytical, experimentalExperimental techniques, and computer-based theoretical modelling of fundamental properties and elemental processes, provide new opportunities to develop the next level of whole-of-reactor pyrometallurgical furnaceFurnace models. These models have the potential to significantly improve the prediction of, and adding value to, industrial operations. In non-ferrousNon-ferroussmeltingSmelting, the starting point of these models is the development of multicomponent thermodynamic databases for gas-slagSlag-matte-speiss-metal-solids phases supported by systematic experimentalExperimental research. The whole-of-reactor-models additionally should take into account kineticKinetic processes taking place at micro- and macro- scales, and other key factors. Examples of applications of the latest research tools and modelling approaches to analysis of industrial flash and top submerged lance (TSL) sulphide smeltingSmelting processes are presented. Different levels of industrial modelling are discussed from elemental local reactions, through general and more detailed whole-of-reactor-models, to plant sections and further to whole plant operation models. Some principles for development of pyrometallurgical reactor models are discussed.

A special desulphurization slagDesulphurization slag accrues during the processing of ironIronoreOre to steelSteel, which is needed to generate high quality steelSteel. Sulphur removing is done by different technologies, but the most common one is the generation of a high sulphur containing slagSlag by sulphur affine elements. Currently, this desulphurization slagDesulphurization slag is partly recycled, however, huge amounts are still dumped. To utilize this desulphurization slagDesulphurization slag for future purposes, a recyclingRecycling process must be established. Therefore, first characterizationCharacterization of this material started some years ago at the Chair of Nonferrous Metallurgy, Montanuniversität Leoben. Subsequent trials in lab scale size were performed, also some investigations for different treatment steps were evaluated, starting with a parameter study in a hot stage microscopeHot stage microscope at various gas-atmospheres. Finally, the developed recyclingRecycling process concept was verified in pilot scale trials to confirm the new recyclingRecycling technology. Due to the successful treatment process, also a patent was applied.

Corrosion mechanisms between high melting synthetic ferronickel slags and refractory were investigated. The used slags were prepared by mixing and melting of specific oxides. Substrates of the applied refractory material and specimens of FeNi slags were heated in a hot stage microscope up to 1650 °C. The experiments were performed under a defined gas atmosphere of 60% CO and 40% CO₂. A further examination of the formed phases between slag and refractory occurred by scanning electron microscope. The investigations indicate that the slag penetrates between magnesia grains and partly dissolves magnesia. Spot analyses show that iron diffuses into the magnesia grains, which transform to magnesiawustite, meanwhile SiO₂ forms different types of olivine like forsterite and monticellite. Thermodynamic calculations confirm the formation of these phases. The combination of practical lab scale experiments and thermodynamic calculations should finally contribute to an improvement of the refractory lifetime and performance.

Since the development of the top-submerged lance (TSLTsl) technology for copperCopper and lead smeltingLead smelting by the cooperation of Mount Isa Mines (MIM), now owned by Glencore, and the Commonwealth Scientific Industrial Research Organisation (CSIRO) the core of the ISASMELT™ISASMELT™ technology has always resided in the lance system. Through continuousContinuous innovation and operation of our own smelters, first at MIM, subsequently at Mopani, and also at both the Kazzinc CopperCopper and Kazzinc LeadLead smelters, Glencore Technology have expanded the core equipment supply to enhance the plant operability. The success of Glencore Technology’s expertise can be directly measured by the success of the Kansanshi Copper SmelterCopper smelter plant, which achieved 100% nameplate capacity within three months of start-up. This paper describes the ISASMELT™ core equipment and how it is applied to smelt sulfideSulfide materials. It highlights the strength of the ISASMELT™: continuousContinuous innovation to facilitate the versatility and continued increased capacity with every plant implementation.

The sulfideSulfidesmeltingSmelting industry is striving for up-scaling their operations by increasing the throughput and efficiencies of the furnaces. The physical phenomena related to refractoryRefractory materials prevailing in smelters and furnaces are highly complex. The refractoryRefractory materials are exposed to fairly high temperatures, thermo-mechanicalThermo-mechanical stresses, penetration of pores, erosion and chemical corrosionCorrosion. The application of numerical simulationSimulation tools is needed for the refractoryRefractory engineering task to consider those phenomena and to evaluate the impact of operational regimes on the refractoryRefractory design and finally on the integrity of the furnaces. The work discusses case studies of simulations addressing problems and questions related to the refractoryRefractory design process. Practical simulationSimulation approaches which employ simplified models are introduced as the engineering process demands results in a reasonable time.

In non-ferrousNon-ferrous metal furnaces the installed magnesiaMagnesia-chromiteChromiterefractoryRefractory lining is exposed to several stresses, rather complex in their interaction. Therefore, a detailed investigation and understanding of wear mechanisms through “post mortem studies” is an important prerequisite for refractoryRefractory producer. Additionally, in order to determine the most suitable refractoryRefractory products and to improve the lining life of refractories, practical corrosionCorrosiontestingTesting with processing slags is performed. For this purpose the test-facilities, such as induction furnaceFurnace, rotary kiln but also cup test and drip slagSlag test, allow the best possible understanding of chemothermal brick wear on pilot scale. Prior to testingTesting a complete mineralogical investigation, thermo-chemicalThermo-chemical calculation via FactSageTM of the slagSlag was carried out. Based on such research results, combined with specific process knowledge RHI Magnesita can recommend appropriate brick lining solutions for non-ferrousNon-ferrous metal furnaces.

In non-ferrous metallurgyNon-ferrous metallurgy the service life of refractoryRefractory materials typically ranges from several weeks up to three years or more and is strongly dependent on operating conditions. To support our customers with the most viable refractoryRefractory solution for their needs RHI Magnesita follows a structured approach of thermo-chemicalThermo-chemical calculations, experimentalExperimental evaluation from lab scale up to industrial field tests and post-mortem analysis of used refractoryRefractory materials. This paper will give an overview of the RHI Magnesita refractoryRefractory selection process and the most recent developments of the experimentalExperimental setup for the so called HF-IF test. This is a dynamic corrosionCorrosion test that allows to determine fundamental properties of different refractory materialRefractory material types under process conditions subjected with respective customers process materials. The HF-IF experimentalExperimental procedure is an excellent tool to simulate refractoryRefractory wear in industrial processes, diminishing risks associated with plant trials and support decision making to choose the optimal refractoryRefractory solution for the customer.

This paper presents results of investigations performed as part of a Root-Cause-Failure-Analysis (RCFA) of a DC smelting furnace that was brick lined with MgO-based refractories. An unusual continuous contraction of the furnace hearth was identified during operation. Cracks in the refractories were envisaged after a major shutdown of the furnace. To determine the mechanism and causes of the unusual contraction behaviour of the furnace hearth, refractory samples were taken from the furnace at different locations and subjected to different analysis including Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), QEMSCAN and Electron Probe Micro Analysis (EPMA). Creep testing of refractories under different loads (ASTM C832) was also employed to evaluate the mechanical integrity of the used bricks in comparison with the new ones. Results of the various characterisation analyses revealed that there was an interaction between refractory bricks and molten material during furnace operation, which resulted in reduced creep resistance of the MgO-based refractories. This was verified by comparing creep performance of the used brick samples and new brick samples at different temperatures and applied stresses.

Within conventional copperCopper and nickelNickel-copperCoppersulfideSulfide smelters, ladles of molten matte are fed into converters. These converters blast oxygen-enriched air into the matte, thereby eliminating ironIron and sulfurSulfur. The converting reactions are exothermic and, indeed, the converter heat balanceHeat balance is often a limiting consideration on the smelter throughput. If a portion of the matte were fed in solidified (granulated) form, this would support higher oxygen enrichment, and lower volumes of converter offgas, allowing higher throughput. This approach is not applied in conventional smelters, partly because of the copious amounts of water that must be evaporated in typical granulators, as in the Kennecott-Outotec process. The current paper recalls a waterless matte granulator that had been pioneered in the 1990’s, and is applicable to conventional smelters. A mathematical formulation is presented that can be used in the context of simulation-based optimizationSimulation-based optimization, to estimate the size and impact of waterless matte granulationMatte granulation.

Sulfur emissionSulfur emission in the form of SO₂ in flue gasesFlue gases is one of the most serious atmospheric pollutants associated with coalCoal combustion and non-ferrous metalsNon-ferrous metals production. The carbonate eutectic method for removing SO₂ from flue gasesFlue gases at 723–923 K was initially proposed in the 1970s but despite its great efficiencyEfficiency (SO₂ concentration in the flue gas after purificationPurification reached 0.003 volume %), it could not be implemented by industry due to the complexity of the carbonate melt regeneration stage. Earlier we proposed a method suited to coalCoal-firing power stations where the melt was regenerated using COCo as a reducing agent. However, most metallurgical plants do not use coalCoal and therefore lack a large source of CO. Here we propose a method for removing sulfurSulfur from the carbonate eutectic meltCarbonate eutectic melt by purging it with natural gasNatural gas or a natural gasNatural gas/air mixture, which are available in the vast majority of metallurgical plants. This reaction leads to the reductionReduction of sulfate to H₂S gas that leaves the melt. The experiments we conducted show that nearly complete sulfurSulfurremovalRemoval from the melt is possible at 823 K and that the reaction rate is sufficiently high for a large scale process. One can foresee that this carbonate melt-based SO₂removalRemoval technique may become a practical and economically attractive method for limiting sulfur emissionSulfur emission to the atmosphere from non-ferrousNon-ferrous metallurgical processing plants.

LeadLeadblast furnaceBlast furnace water-jacket stability was investigated by examining samples from the Port Pirie LeadLead Smelter. The compositions of the phases formed in the samples were analysed using Scanning Electron Microscopy (SEM)SEM and Electron Probe X-ray Microanalyser (EPMA). Phase equilibriaPhase equilibria analysis and thermodynamic modellingThermodynamic modelling was undertaken using FactSage with latest thermodynamic databaseThermodynamic database for the slagSlag/matte/metal/speiss/solids multi-component Cu₂O–PbO–ZnO–Al₂O₃–CaO–MgO–FeO–Fe₂O₃–SiO₂–S major and As–Bi–Sb–Sn–Ag–Au minor elementsMinor elements system. Results indicated that the stability of the water-jacket steelSteel wall without freeze-lining is influenced by formation of the complex Fe-rich speiss phase at critical As concentrations. The integrity of the furnaceFurnace walls with freeze-lining is critically dependent of the stability of the oxide-based freeze-lining which is dependent on various factors including most critical one—the proportion of solids determined by the slagSlag chemistry and fluxing. Thermodynamic modellingThermodynamic modelling of the leadLeadblast furnaceBlast furnace operation indicated limiting thermochemical conditions for the water-jacket stability. Factors and controls critical to the water-jackets integrity are discussed.

This paper discusses sustainabilitySustainability considerations in primary copper smeltingCopper smeltingSmelting using selected examples of practices at ASARCO LLC, an integrated U.S. primary copperCopper producer. Using the classic Brundtland Commission definition of sustainable developmentSustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copperCopper mining and smeltingSmelting practices can be made sustainable. The examples used to illustrate sustainabilitySustainability considerations include: (1) adoption of flash smeltingFlash smeltingSmelting; (2) emission reductionReduction and process improvement associated with anode refiningRefining of blister copperCopper and the converter retrofit project, and (3) preliminary research findings on alkali treatment of copper smeltingCopper smeltingSmelting slags and copperCoppermine tailingsMine tailings.

Arsenic can be found in different sulfidic copper concentrates and residues, which for several years have commonly been used in copper metallurgy, as the “arsenic-free” resources are getting rare. Due to the high toxicity the removal of arsenic in the copper smelting process is a very important topic. The typical chemical slag and sulfur attack on the refractory material is getting enhanced by the presence of arsenic. This work deals with post-mortem investigations of a magnesia-chromite brick and castable used in copper smelting furnaces showing an additional and increased chemical attack by arsenic. The knowledge on the wear behaviour is not only based on a detailed chemical and mineralogical characterization, but also on thermochemical FactSageTM calculations, which are carried out on provided post-mortem samples. Post-mortem investigations on used refractory materials represent an important prerequisite for the product development, as well as for special engineered lining concepts to support our customers.

CopperCopper sulphide processing technologies face increasing pressures associated with decreasing concentrate grade leading to increasing thermal inefficiency and lower productivityProductivity. Impurity concentrations are on average increasing, creating potential environmental risk and additional treatment costs. In copperCopper flash smelters dust, partially oxidised materials and fume formed from the condensationCondensation of volatile impurities, are routinely recycled to the feed. In the converting stage the heat balanceHeat balance is maintained by charging anode reverts and other inert materials. In both cases, the thermal energyEnergy available from sulphide oxidationOxidation is not fully utilised or optimised. The productivities of both smelter and converter stages can be potentially increased through the addition of a high copperCopper, low ironIron, low impurity precipitated copperCopper product. Calculations are carried out for fayalite smelter and calcium ferriteCalcium ferrite converter slags using an optimised FactSage thermodynamic databaseThermodynamic database. The potential for significant increases in smelter and converter productivities using existing technologies are predicted.

Peirce-Smith convertingPeirce-smith converting (PSC) is applied for roughly 50% of primary nickelNickel and 70% of primary copperCopper production. PSC cycles produce batches of ironIron-free sulfideSulfide matte (or blister copperCopper, in the case of copperCopper smelters), that are subject to further processing. However, the number of cycles that can be performed simultaneously is limited by the offgas handling system. Moreover, PSC suffers from variation in the yield and duration of the cycles. This variation is managed by conventional smelter designs, in which the upstream smeltingSmelting capacity exceeds the nominal converting capacity; PSC is thus a major bottleneck in conventional nickelNickel and copperCopper smelters. StabilizationStabilization and standardization of PSC operations can therefore increase smelter throughput. The current paper presents a discrete event simulationDiscrete event simulation (DES) framework to assist in smelter debottleneckingDebottlenecking. It features random number generation to represent cycle variability, and time-adaptive finite differences to represent thermochemical complexity. Preliminary computations are presented.

At Anglo American PlatinumPlatinum’s Polokwane Smelter, radarRadar instruments are being used to provide continuousContinuous measurement of the concentrate feed level in the six-in-line electric furnaceElectric furnace used for smeltingSmelting of nickelNickel-copperCopper concentrates containing platinum group metalsPlatinum group metals (PGMs). The radarRadar instruments are installed directly on the furnaceFurnace roof, and a mechanical system has been designed to protect them from radiationRadiation and elevated freeboard temperatures and pressures. Signal validation criteria have been implemented to ensure that proper level measurements are being used by the PLC system. The feedback from the radars has provided an improved understanding of the furnaceFurnace behaviour with respect to concentrate feed level controlControl, individual feeding events, global feed rates, feed distributionDistribution and bath disturbances. In combination with a dynamic mass balanceMass balance for continuousContinuous calculation of liquid level in the furnaceFurnace, the radarRadar measurements have enabled more precise feedback controlControl of the concentrate blacktop depth. In turn this has yielded improvements in furnaceFurnace stability.

For the impurities in the copper smeltingCopper smelting waste acid, SO₃, Cu, As, Pb, Zn, Re and other elements enter the waste acid and generate a lot of arsenic residueArsenic residue, gypsumGypsum and neutralized residueNeutralized residue, in which Cu, Zn and Re metals have not been recycled. Cu, Re and As are separated by step-wise vulcanization. The valuable metalsValuable metals of Cu, Zn and Re are recovered by separating zincZinc through pH adjustment. Calcium injection is conducted for boiler for reducing the amount of SO₃. The residues generated in the form of arsenate and hydroxide will be returned together with arsenicArsenic filter cake for smeltingSmelting treatment so as to achieve the purpose of valuable metal recyclingRecycling and solid waste reductionReduction and harmless treatment.

The converter-less nickel matteNickel mattesmeltingSmelting technology (DON) adopted more than 20 years ago in Boliden Harjavalta smelter has been since that applied successfully to the processing of large number of nickelNickel sulphide concentrates of various Ni-to-Cu ratios and MgO contents. The operational point of the technology is far from the conventional primary nickel smeltingNickel smelting in the smeltingSmelting-converting route. Therefore, a careful scouting of distributionDistributionequilibriaEquilibria of the base and trace elements in the smeltingSmelting conditions of DON process has been conducted, in order to obtain quantitative information about the equilibriaEquilibria and thermodynamic properties of the nickelNickel mattes at low ironIron concentrations, less than 10 wt% [Fe] in matte. The series of investigations has included novel experimentalExperimental and analytical techniques for increasing the reliability and sensitivity of the phase equilibriaPhase equilibria as well as the element distributionElement distribution observations carried out in typical high-grade nickel matteNickel mattesmeltingSmelting conditions.

Managing complex material streams within a lead smelting/reduction process has a long history at Aurubis. After modernization of the secondary lead smelter in 1991, Aurubis operates an electric furnace and a Peirce Smith converter to process complex secondary materials. This process links the copper and the lead metallurgy allowing Aurubis to properly combine primary and secondary process lines to optimize the processing of complex raw materials and smelter intermediates. However, combination of copper and lead metallurgy processing requires a continuous evaluation as raw material quality and composition varies. This paper describes Aurubis lead smelter processing and provides some fundamental considerations to optimize the lead processing, in particular with aspects related to speiss formation.

Nickel-sulfide minerals are normally associated with copper and iron sulfides and often contain a minor amount of valuable metals such as cobalt and detrimental impurities such as arsenic. Metal losses in slag vary from process to process during the pyrometallurgical production of nickel and, depend on the feed composition, slag chemistry and operating conditions. Maximiz the metal recovery is one of major considerations to optimize operating condition for nickel smelting/converting processes. At the same time, the deportment of minor elements between various phases during nickel smelting is of great importance by smelter operators. The Multi-Phase Equilibrium (MPE) is a thermodynamic package developed by CSIRO for simulating reactions between phases in multi-component and multi-phase systems [1]. Over the years the capability of the MPE model has been extended to cover the behavior of a large number of elements in high temperature systems. The sulfide smelting module of the MPE, which covers the minor elements such as As, Bi, Sb, Pb, Se, Te, Sn, Co and Zn, is capable of modeling the deportment of major and minor elements between various phases during nickel smelting. In this article the application of the MPE model in modelling the nickel smelting process is presented. The modelling results on the majors and minors are compared with the plant data. The deportment behaviour of arsenic in nickel smelting was analysed and the impact of slag chemistry on slag properties was modelled. These results can assist process metallurgists in exploring the optimum fluxing strategy for smooth operation and the potential practices for improving arsenic removal.

Through metallurgical calculation and process analysis based on metallurgical theory, it is aimed to raise the concentration of smelting oxygen and improve the update speed of reaction interface, accelerate the reaction and achieve a high-intensity smelting at the stage of converting. The PM plant has launched a theoretical research on model of high-intensity converting aiming at increasing the oxygen concentration of converting, carried out transformation of Kaldo furnace converting system, performed a series of industrial trial operations, conducted multiple rounds of tracking test and data comparison in reducing the furnace cycle, lowering the unit consumption of fuel and stabilizing the furnace lining life. The move has practically tested and verified the correctness of high-intensity smelting theory.

Situated in the oblast of East Kazakhstan, the Ust-Kamenogorsk Metallurgical Complex has spent the past twenty years renovating and remodelling itself as a modern polymetallic sulphide smelting facility, and a regional centre of excellence for custom smelting. Along the way there have been changes to the company structure, introduction of new technologies, investments in expanded capacity, environmental improvements, and addition of new metal products and by-products to the site’s repertoire. These changes have been gradual and incremental, but taken together they represent a significant contribution to placing Kazakhstan’s sulphide smelting industry on a strong foundation for enduring success in the international custom smelting market. In achieving these changes, a workforce that was historically isolated from much of the world now has recognised expertise, internationally competitive skills, and confidence to embrace the future. Further improvements in energy efficiency, environmental compliance and polymetallic processing capabilities are challenges that UKMC stands ready to face.

To capture efficiently the valuable trace metals from nickel slag using electric furnace, it is important to study their distributions between the slag and metallic phases in the furnace. It is impossible to calculate accurately these distributions without experimental measurements. Therefore, in this work, selected trace metal distributions and phase equilibria between K₂O containing iron-silicate slags and a metallic Ni-Fe-Cu alloy in nickel slag cleaning furnace conditions were studied. The experimental method developed and applied during the work, involved a modified quenching technique that included equilibration of the samples in semi-sealed quartz ampoules in an inert atmosphere and metallic Fe saturation. The use of the semi-sealed quartz ampoule prevents the escape of volatile elements from the sample during equilibration. Chemical compositions of the phases and the trace elements were analysed by EPMA. From the measured compositions, the trace metal distribution coefficients between the molten Ni-Fe-Cu alloy and slag were calculated.

The Top Submerged Lance (TSLTsl) technology, developed in the 1970s, is now widely used for the processing of a range of materials. TSLTsl technology for continuous convertingContinuous converting was first patented in the 1990s. The process is based on the use of calcium ferriteCalcium ferriteslagSlag. Although this slagSlag system had been applied elsewhere the phase equilibriaPhase equilibria had not been thoroughly investigated. This leadLead to a collaboration between the Process Technology group of Mount Isa Mines, now part of Glencore, and the PyrometallurgyPyrometallurgy Innovation Centre (PYROSEARCH) at The University of Queensland. Through multiple research programs this complex system was successfully investigated. The results were then implemented within thermodynamic modellingThermodynamic modelling tools. This combined new knowledge was then applied to the design and industrial implementation of the TSLTslcontinuous convertingContinuous converting technology, ISACONVERT™. This paper describes the key findings of the research and how this was applied to the industrial implementation of the technology.

PyrrhotitePyrrhotite is an ironIron deficient, low nickelNickel content sulfide mineralSulfide mineral that is commonly associated with pentlandite, a nickelNickel-rich sulfideSulfide; and are both main components of the nickelNickel ore mined in Sudbury. PyrrhotitePyrrhotite tailings generated in the concentration of Ni ores are stored in tailing reservoirs and presents serious environmental risks including acid mine drainageAcid mine drainage. This study investigated the potential of converting pyrrhotitePyrrhotite into a valuable resource through the use of fluidized bed roastingFluidized bed roasting, in which the mineral will be oxidized to produce iron oxideIron oxide and SO₂ gas. These products can then be used to create ironIron for high-grade steelSteel and elemental sulfurSulfur. ThermogravimetricThermogravimetric analysis of Sudbury pyrrhotitePyrrhotite was performed to study the oxidation kineticsOxidation kinetics, supporting the feasibility of this process. Further, energyEnergy and materials balance was carried out to establish the basic parameters of a possible roasting process.

A thermal upgradingThermal upgrading process by which nickelNickel value can be concentrated in a ferronickel alloyFerronickel alloy is a possible alternative to treat Sudbury pyrrhotitePyrrhotite (Po) tailings with nickelNickel content of 0.5–1.5 wt%. The basis of this process is precipitationPrecipitation of Ni from Po at high temperatureTemperature once Fe/S ratio in the ironIron-deficient Po is shifted towards stoichiometric or near stoichiometric FeS (troilite) either by the addition of ironIron and/or the removalRemoval of sulfurSulfur. For the ironIron addition route, the reaction between elemental ironIron and nickeliferous pyrrhotiteNickeliferous pyrrhotite to produce ferronickel alloyFerronickel alloy and Ni-depleted ironIronsulfideSulfide phase plays a critical rule. In this paper, the formation mechanism of ferronickel alloyFerronickel alloy was investigated using the diffusion couple technique to better understand the nickel diffusionNickel diffusion behavior in the ironIron and sulfideSulfide phases.

Dongying Fangyuan Nonferrous Metals Co., Ltd. has developed a new technologyNew technology to produce anode copperAnode copper from concentrates through only two furnaces. This new technologyNew technology is called the Two-Step Copper SmeltingTwo-step copper smelting Process. This paper presents the commercial application of the Two-Step Copper SmeltingTwo-step copper smelting Process and its operating conditions. The key features of the Fangyuan Two-Step Process are as follows: (1) feed materials, including concentrates and fluxFlux, are mixed without pretreatment and fed into the Submerged Lance SmeltingSmelting (SLS) furnaceFurnace; (2) high grade white metal (WM) produced by the SLS furnaceFurnace is transferred via WM conduit into one of the two Submerged Lance Converting and RefiningRefining (SLCR) furnaces; and (3) the two SLCR furnaces blow alternatively to maintain continuousContinuous operation of the whole production chain. The new smelter started operation in October 2015 with a processing design capacity of 1.75 Mt/year of mixed feed and has been operating for over 30 months.

One of the keys to success in process development is incremental scale-up, allowing for potential problems to be identified and rectified. The ISASMELT™ISASMELT™ top submerged lance (TSL) process was developed to maturity using this method by Mount Isa Mines, now owned by Glencore. Commercialization only occurred once the process had been proven on each scale and as a result the ISASMELT™ technology now operates successfully around the world. An important parameter in the evolution of the technology has been the furnaceFurnace campaign life. The initial commercial scale furnaces had minimal water-coolingCooling. Although this led to shorter campaign lives, an extended development program resulted in the achievement of four-year campaign lives, without any water coolingCooling. In tandem to the refractoryRefractory designs Glencore Technology, supplier of the TSL technology, has progressed cooled copperCopper lining designs for application to both the ISASMELT™ and ISACONVERT™ furnaces allowing for ultimate flexibility in the lining choice. This allows each ISASMELT™ISASMELT™ operating site to minimize their overall life-cycle costs by balancing their campaign life with lining costs, energyEnergy inputs, and other shutdown requirements.

The oxygen bottom blown copper smeltingCopper smelting process is a new technologyNew technology which has been widely applied to the copperCopper production in China. In this work, a computational thermodynamicsThermodynamicsmodelModel for this technology has been established, based on smeltingSmelting mechanism and theory of Gibbs free energy minimizationGibbs free energy minimization. The calculated results from the modelModel agree well with the actual industrial data, indicating that the modelModel can be used for the predictions under different operating conditions. The tendencies of the key parameters (such as Cu losses and Fe₃O₄ content in slagSlag) and the distributionDistribution ratios of the minor elementsMinor elements (such as Pb, Zn, As, Sb and Bi) can be predicted by adjusting the oxygen/oreOre ratio charged into the bottom blown copper smeltingCopper smeltingfurnaceFurnace. The modelModel can be used to monitor and optimize the industrial operations of the oxygen bottom blown copper smeltingCopper smelting process.

Freeport-McMoRan Inc. operates an ISASMELTTMIsasmelt™furnaceFurnace for the smeltingSmelting of copperCopper concentrate at the Miami Smelter in Claypool, Arizona. In May 2017, the furnaceFurnace was restarted after incorporating newly designed copperCoppercoolingCooling elements from just above the tap hole to the underside of the roof. The objective of the improved coolingCooling design was to extend campaign life by eliminating existing failure mechanisms with the wall refractoryRefractory. In addition to upgraded bathline coolers and complete coverage of the gas offtake transition, or ‘kettle’, with plate coolers, a novel arrangement of coolers was installed in the remaining freeboard area. The shell required significant cutting and re-stiffening, as well as extensive modification of the coolingCooling water piping. Based on performance observed to date, it is expected that smelter throughput will be increased due to extended ISASMELTTMrefractoryRefractory campaign life.

Effects of fluxFlux, vulcanizing agentVulcanizing agent and reductantReductant on slagSlag cleaning in new-type slag cleaning furnaceSlag cleaning furnace (Φ3.6 × 8.1 m) were investigated under the conditions including smeltingSmeltingtemperatureTemperature of 1200 and 1250 °C, settling time of 30 and 60 min, and Fe/SiO₂ of 1.7–1.9. The results show that addition of SiO₂Sio₂, B₂O₃ or CaF₂ into original copper smeltingCopper smeltingslagSmeltingcanSlag improve settling separationSeparation effect. Though no effect on copperCopper recoveryrecoveryRecovery, addition of FeS can provide heat required by reaction with oxygen and reduce copperCopper dissolution in spinel phase and slagSlag. CopperCopper content in discarded slagSlag can be controlled at 0.26% under the optimum comprehensive conditions with ratio of oxygen to natural gasNatural gas of 1.6.

Valorization of slag from metallurgical industrial processes becomes ever more important as this may help optimizing and reducing the use of natural resources such as rock and sand. In view of this objective, metallurgical processes have to be analyzed in order to modify the slag composition so that it will meet the expected requirements of potential users of these resources. This paper gives the results of a thermodynamic analysis of the flash smelting process to understand the impact of operational parameters on slag chemistry and elemental partitioning in the process. It is shown that an increase of the matte grade and temperature leads to higher deportment of Pb, Zn and As to the slag. With increasing matte grade the volatilization of these elements decreases. Furthermore, the results indicate an increasing solubility of Cu and S in slag at higher temperatures.

In most smeltingSmelting operations, there is a strong incentive to improve safety, reduce downtime and extend the campaigns of furnaces and related equipment. An asset managementAsset management strategy that is based on information, rather than simple throughput metrics and intuition, can be developed to improve uptime and unlock value currently unrealized at existing smelters. Advances in digital technologyDigital technology, including data analysis, modelling and monitoring for hot pyro-metallurgical vessels, make it possible to assess the current condition of an asset, as well as to make more informed projections about its future condition, using on-line and historical data. This would allow practices around asset managementAsset management to be more proactive and less reactive, with the end-result of optimized uptime. ‘Digital Asset ManagementAsset management’ describes a concept in which digital technologyDigital technology is used to support an asset managementAsset management strategy and accelerate decision-making by providing information on what, why and how an asset should be designed, operated or maintained. With the overall goals of effective resource utilizationResource utilization, optimized operationsOptimized operations, capital efficiencyCapital efficiency and social acceptance, Smelter 4.0Smelter 4.0 is a program of holistic improvement and is underpinned by the effective use of data to drive decisions. This paper focuses on Asset Reliability, which is one of the improvement pillars of Smelter 4.0Smelter 4.0, and introduces a methodology that is aimed at closing the gap between recorded data and evidence-based decision-making through Digital Asset ManagementAsset management.

Kennecott Utah CopperCopper aims to extend anode furnaceFurnace campaigns to more than three years. As part of that goal improvements are sought on anode-furnaceFurnace tuyere-area refractoryRefractory performance. Kennecott and Praxair developed high pressure nitrogen refiningRefining for the OxidationOxidation Stage which shortened anode furnaceFurnace fire refiningRefining cycles by up to two hours per cycle. Future developments include optimizing the ReductionReduction Stage’s steam-gas reforming and achieving coherent jet tuyereless refiningRefining.

Water-quenched samples were taken from a commercial flash furnaceFlash furnace at three levels along its reaction shaft during operation at high feed rate. The samples were subjected to a series of analysis and observation. Such processes of the feed in reaction shaft as oxidationOxidation, desulfurization, melting, slagSlag and matte formation and etc., variations of particle size along axial and radical direction of the shaft are investigated. The following smeltingSmelting mechanism in reaction shaft named as “Multi-particle and multi-phase fusion modelModel” is proposed: (1) Fragmentation and collision of concentrate particles take place simultaneously in reaction shaft with particle size growing up. Collision produces large-size “unit melt” which falls into the reaction layer in the settler bath. (2) In the settler reaction layer below the shaft, weak bath smeltingSmelting reactions take place among the shaft products, producing final matte and slagSlag which separate into two layers. (3) The processes in the shaft are all progressive along the whole height of the shaft. The predominant reaction in the shaft is oxidationOxidation, not reductionReduction.

Acousto Ultrasonic-Echo (AU-E) is a technique developed to provide accurate measurements of the refractoryRefractory lining wear in operating smelters based on the principles of stress wave propagation. The objective of the system is to provide feedback for the continuousContinuousoptimizationOptimization of the overall smelter operation. In some cases, the AU-E refractory lining measurementsRefractory lining measurements have allowed clients to extend their smelter campaigns and operate safely for several years beyond their planned reline schedule. In other cases, AU-E results inform clients of serious issues within their furnaceFurnace allowing them to shut down their smelters ahead of predicted failures and possible disasters. This paper presents the results of several smelter AU-E inspections of the hearth and sidewall. These case studies demonstrate how the AU-E results were used to positively affect the smelter operation.

In this research, both the kinetics and the mechanisms of the roasting of a sphaleriteSphalerite concentrate from the Bafgh mining complex in Iran were investigated. The oxidationOxidation process was performed in a muffle furnaceFurnace in air and the effects of time and temperatureTemperature on the degree of oxidationOxidation of the zincZincsulfideSulfide sample were quantitatively studied. The experimentalExperimental data were fitted to the shrinking core modelShrinking core model. In the temperatureTemperature range of 650–800 °C, the rate-controlling step was the chemical reaction between the zinc sulfideSulfide and oxygen with an activation energyActivation energy of 103 kJ mol−1. On the other hand, in the temperatureTemperature range of 850–950 °C, the rate-controlling step was oxygen diffusion with an activation energyActivation energy of 50 kJ mol−1. Also, the roasting process was studied using thermogravimetricThermogravimetric (TGA) and derivative thermogravimetricThermogravimetric (DTGA) techniques.

Recently, replacing Pierce-Smith converting process with the oxygen bottom-blowingBottom-blowingcontinuous convertingContinuous converting technology has become a new research focus. Based on the principle of Gibbs free energy minimizationGibbs free energy minimization, the thermodynamic modelModel of oxygen bottom-blowingBottom-blowingcontinuous convertingContinuous convertingmultiphase equilibriumMultiphase equilibrium system has been established. The elements distributionDistribution behavior is calculated at the same burdenBurden composition and operation parameters as the industrial production. The results show that the absolute errors of the mass fraction (wt%) of Cu, Fe, S, Pb, Zn, As, Sb, Bi in crude copperCopper are 0.06, 0.0030, 0.070, 0.38, 0.39, 0.020, 0.017, 0.034, 0.010, respectively, and the absolute errors of the mass fraction (wt%) of Cu, Fe, S, Pb, Zn, As, Sb, Bi in slagSlag are 0.53, 0.81, 0.020, 0.23, 2.5, 0.0048, 0.0010, 0.0030, 1.49, respectively. The calculated results agree well with the actual industrial production data, indicating that the modelModel can be well applied in the oxygen bottom-blowingBottom-blowingcontinuous convertingContinuous converting practice.

Large quantities of copperCopper complex resources are produced globally and urgent to be cleanly processed. This article presents a thermodynamic analysis of mixed smeltingSmelting process including low-grade polymetallic copperCoppersulfideSulfide concentrates, high copperCopper content sulfideSulfide concentrates, metallurgical by-products (copperCopperremovalRemovalslagSlag from leadLead metallurgy), and copperCopper powder from electronic waste. A top blown smeltingSmelting reactor to simulate mixed smeltingSmelting process is developed using a metallurgical process simulator, METSIM. Reactor parameters, heat loss and phase distributions are estimated from actual plant data. The proper proportion between complicated primary and secondary copperCopper resources is determined by analyzing the influence of the feed rates of various resources, oxygen, silicaSilicafluxFlux and revert on the smeltingSmelting performance. Autogenous smeltingSmelting process is built by optimized matching materials of copperCopper complex resources, in terms of the reactor temperatureTemperature, copperCopper content in matte and slagSlag, and the percentage of magnetite in slagSlag.

The Peter HayesPeter hayes Symposium on PyrometallurgyPyrometallurgy, held as part of ExtractionExtraction 2018, is an acknowledgement of his contributions to the basic science and principles underpinning modern pyrometallurgical processing. After completing his PhD at Strathclyde University, Scotland, in 1974, Peter took up a teaching position at The University of Queensland, Brisbane, Queensland, Australia in 1976. Peter HayesPeter hayes’ research at the University since then has been focussed on: The mechanisms and kinetics of heterogeneous solid/solid, gas/solid and liquid/solid reactions, andExperimentalExperimental measurement of phase equilibriaPhase equilibria in complex high temperatureTemperature metallurgical systems.This paper provides a brief biography of Dr. Peter HayesPeter hayes and gives a full listing of Peter HayesPeter hayes’ publications.

The Trail smelter of Teck Metals Ltd. produces about 90,000 tonnes of leadLead per year through two stages of refiningRefining following KIVCETTMsmeltingSmelting. Bullion from the KIVCET furnaceFurnace is first treated in a pyro-refiningRefining plant in preparation for BettsBettselectrorefiningElectrorefining which makes 99.99% pure leadLead. Pyro-refiningRefining consists of number of integrated unit operations to remove primarily copperCopper, arsenicArsenic, antimonyAntimony and tinTin. The operation of this plant to meet the specifications for electrorefiningElectrorefining requires attention to bullion management and selective use of reagents. The processes used for pyro-refiningRefining are reviewed in terms of chemistry and controlControl.

Over the past few decades the carbon intensityCarbon intensity of ironmaking and steelmakingSteelmaking has been reduced considerably through improved efficiencyEfficiency in blast Blast furnacefurnaceFurnace ironmaking, partial replacement of coke with less carbon-intensive fuels, and increased use of scrap and direct-reduced ironIron in steelmakingSteelmaking. To evaluate possible further reductions in carbon intensityCarbon intensity accurate process information is needed. A preliminary test of the fidelity of publicly reported data as a source of process information is reported here. The sources are industry roundups of electric furnaceElectricfurnaceFurnacesteelmakingSteelmaking and blastBlast furnacefurnaceFurnace ironmaking (published by the Association for IronIron and SteelmakingSteelmaking Technology), and data recorded by the Environmental Protection Agency under the US Greenhouse Gas Reporting Program. From a comparison for an integrated steelmakingSteelmaking plant and an electric furnaceElectricfurnaceFurnace plant, it appears that the values from the two data sources are consistent. The comparison does rely on process details such as the quantitative relationship between injected oxygen and carbon emissions in electricElectric furnacefurnaceFurnacesteelmakingSteelmaking.

ExcavationExcavation of industrial-scale furnaces allows for the systematic study of reaction sequences by identifying the different reaction zonesReaction zones within the furnaceFurnace. In 2013, Transalloys excavated a 48 MVA submerged arcSubmerged arcfurnaceFurnace that was used for silicomanganeseSilicomanganese production using the ore-based routeOre. The excavationExcavation method was reported elsewhere as was observations made in terms of refractoryRefractory wear and modes of electrical energyEnergy dissipation prior to excavationExcavation. The paper presented here, reports on the process reaction zonesReaction zones observed during the excavationExcavation and subsequent phase chemical analyses of a number of process samples obtained during the excavationExcavation. The zones identified were a loose burdenBurden zone, a dry coke-bed zone, a wet coke-bed zone, a hard build-up zone, and an alloy zone. The results are compared to observations made in the excavationExcavation of an industrial-scale SAF and a pilot-scale SAF in Norway. The presence of the hard build-up zone below one of the electrodes and absence of a slagSlag zone below all three electrodes are unique features of the SAF excavated at Transalloys.

Prediction of the thermal duties of copperCopper coolers in freeze lined furnaces is challenging. Where copperCopper coolers are immersed in liquid slagSlag the heat transfer is often defined by a natural convection cell immediately adjacent to the wall, in the absence of other factors producing forced convection. SlagSlag coolers are typically not fully immersed, slagSlagtemperatureTemperature, liquidusLiquidus and superheat can vary, and bath levels may change significantly with batchBatch tapping, leading to substantial variations in radiationRadiation heat fluxes. RadiationRadiation heat transfer is discussed with reference to the non-obvious impact of slagSlagliquidusLiquidus on radiationRadiation losses in the exposed coolerCooler sections. Reference is made to literature and the results of analytical and FEM models.

MagnesiaMagnesia-based refractoryRefractory is generally used in an electric arc furnaceElectric arc furnace (EAF) due to its relatively high corrosionCorrosion resistance and strength at high temperatures. However, the magnesia refractoryMagnesia refractory is attacked by EAF slagSlag and thus the lining life continuously decreases. Thus, it is significant to identify the interfacial reactionInterfacial reaction between magnesia refractoryMagnesia refractory and FeO-rich EAF slags. In the present study, the influence of FeO-rich slagSlag on the corrosionCorrosion behavior of MgO refractoryRefractory was evaluated. The (Fe,Mg)O_ss layer(Fe,Mg)O_ss layer was observed at the slagSlag-refractoryRefractory interface and its thickness increased with increasing content of FeO in the slagSlag. The specific reaction phenomena and formation behavior of (Fe,Mg)O_ss layer were evaluated by thermochemical computing program, FactsageTM7.0.

Data on the kinetics and thermodynamicsThermodynamics of dephosphorizationDephosphorization are analyzed in terms of the dynamic partition ratio, determined by a combination of slagSlag thermodynamic properties and the balance of oxygen supply and consumption. A recently developed phosphate capacity correlation is combined with data on kinetics to quantify the most significant parameters in controlling the interfacial oxygen potential. The role of slagSlag composition, entrained gas fraction and temperatureTemperature are discussed in addition to metal carbon and sulfurSulfur content. It is demonstrated that the mass transport of oxygen in the slagSlag is enhanced by factors increasing conductivity and inhibited by entrained gas. The mass transferMass transfer of phosphorus in the metal is described considering surface renewalSurface renewal induced by CO bubblesBubbles.

Formation of cementiteCementite in the reductionReduction of hematite by CO–CO₂ gas was studied in situIn situ using high temperatureTemperatureXRDXrd (HT XRD) analysis. ReductionReduction of hematite was examined in the temperatureTemperature range 873–1173 K by CO–CO₂ gas mixture with high carbon activity. When carbon activity in the system was 1.5, cementiteCementite was formed only at 1023 K; it was not observed in experiments at 973, 1073 and 1123 K. Formation of cementiteCementite was observed at 923–1073 K when carbon activity increased to 3–5; and at 873 K when carbon activity was 10. Formation of cementiteCementite at 973–1073 K proceeded through metallic ironIron; however, in the reductionReduction of hematite at 873 and 923 K, ironIron was not observed; cementiteCementite apparently was formed directly from wüstite. XRD spectra were used to estimate concentration of carbon in austenite in the process of cementiteCementite fromation.

Condensates produced by SiO(g) and CO(g) have a crucial importance in silicon productionSilicon production. CondensationCondensation will follow the reactions $$ 3\,{\text{SiO}}\left( {\text{g}} \right) + {\text{CO}}({\text{g}}) \to 2\,{\text{SiO}}_{2} + {\text{SiC}}\,{\text{and}}\,2\,{\text{SiO}}\,({\text{g}}) \to {\text{Si}} + {\text{SiO}}_{2} $$3SiOg+CO(g)→2SiO2+SiCand2SiO(g)→Si+SiO2. Solid compounds generated during silicon productionSilicon production contain Si, SiO₂ and SiCSic in different microstructures and amounts. In industrial systems, condensates limit the SiO(g) escape to the off-gas system. On the other hand, they can block the gas flowing from the high temperatureTemperature zone, hence the necessity of studying an optimized condensationCondensation process. This reviewReview discusses SiO(g) condensationCondensation and its interaction with CO(g). The report gives an overview of the condensates found both at laboratory and at industrial scale. The two main compounds are the Si–SiO₂ and the SiO_x–SiC mixtures. The hypothesis on the mechanism of formation of SiC–SiO_x condensates is presented through a wide selection of performed works. The advantages and disadvantages of the former experimentalExperimental procedures are discussed.

Two quartzQuartz types used in the siliconSilicon and ferrosiliconFerrosilicon industry were heated to temperatures of 1600 and 1700 °C. The parameters varied were the temperatureTemperature and the holding time at maximum temperatureTemperature. The amount of quartzQuartz, cristobaliteCristobalite and intermediate amorphous phase were measured using XRDXRD and the internal standard method. Type P showed a much larger ability to transform to cristobaliteCristobalite at lower temperatures than type A. Type P had a larger amount of alkali and alkaline earth impurities. This could have enhanced the transformationTransformation to cristobaliteCristobalite. For quartzQuartz type A the amount of cristobaliteCristobalite was larger at 1600 °C than 1700 °C. This can also be seen for some of the samples of type P at shorter holding times.

Gas injection into liquid steelSteel baths is widely practiced, ever since the early days of Bessemer’s pneumatic steelmakingSteelmaking process. What has not been fully appreciated is the critical role of bubble sizes for delivering higher quality commercial steels than is presently possible. This was first proposed by Prof P. Hayes and his research group. Using a full-scale water modelModel of a typical 4-strand Ladle-Tundish-Mold system, we demonstrate the potential advantages of modifying a typical ladle shroud, to generate microbubbles within the water flowing into the tundish. This is possible by taking advantage of high shear rates and turbulence kineticKineticenergyEnergy available in that region. These microbubbles enhanced the removalRemoval of “micro-inclusions” (hollow glass microspheres) in the 5–50 micron size range, to the upper surface of the tundish. There, they were absorbed into an overlaying “slagSlag” phase. Accompanying CFDCfd studies confirmed that no microbubbles in the size range generated (500–900 μm), pass through the submerged entry nozzles into the moulds.

In order to overcome weak points of steelSteel for its engineering applications, in particular, for environmentally benign, energyEnergy-efficient, lightweight engineering systems, a number of new steels have been proposed, especially to improve strength-to-weight ratio (specific strength). Mass production of these steels, however, has encountered a serious roadblock particularly in the steel refiningSteel refining and castingCasting processes. This is because their chemistries and cleanliness requirements are vastly different from those of the conventional steels, and thus an incremental improvement of the prevailing process technologies is found hard to meet the requirements. In this study, a new process is proposed, which employs inert gas bubblesBubbles in the shroud nozzle, liquid steelSteeldropsDrops in the degassing chamber, and the siphon transportSiphon transport for continuousContinuouscastingCasting. The proposed process which integrates the final refiningRefining and cleaning steps prior to castingCasting is expected to be a technologically disruptive innovation on the conventional counterpart. The effectiveness of the individual steps is discussed with experimentalExperimental results.

Thermodynamic analysis and experiments were conducted in order to verify the feasibility of preparing crude titanium tetrachlorideTitanium tetrachloride (TiCl₄) via the carbochlorinationCarbochlorination of low-grade titanium slagLow-grade titanium slag in molten saltMolten salt. TitaniumTitaniumslagSlag, assaying 74.6 wt% TiO₂Tio₂ with high calcium and magnesium oxide impurities, was treated by an optimized carbochlorinationCarbochlorination process in NaCl molten saltMolten salt. These impurities in the titaniumTitaniumslagSlag were chloridized simultaneously, and chlorination products FeCl₂, MnCl₂, MgCl₂, CaCl₂ and CrCl₃ were collected in the furnaceFurnaceslagSlag. XRD and SEM/EDSEds analysis of residue shown that SiO₂Sio₂ and Al₂O₃ in titaniumTitaniumslagSlag were difficult to chlorinate completely. Theoretical calculations and industrial-scale experimentalExperimental studies reveal the content of TiCl₄ in the products was more than 98.8 wt% and thus proved the feasibility of utilizing low-grade titanium slagLow-grade titanium slag for TiCl₄ preparation by molten saltMolten salt chlorination technology.

A new metallurgical process via sulfideSulfide is proposed: a sulfideSulfide is produced at a high temperatureTemperature from its metallic oxide using gaseous CS₂, and this sulfideSulfide is electrochemically reduced to its metallic state using molten saltMolten salt. This combined process via sulfideSulfide is effective to obtain high purity of metallic powder, even if the metal in its oxide is strongly combined with oxygen. For example, it is not easy to reduce stable oxide TiO_2Tio2, and only Ca can remove oxygen to form α-Ti. However, a fairly large amount of oxygen remains as Ti–O solid solution. Because the solubilitySolubility of S in Ti is very small, this proposal was examined experimentally both on the conversion of TiO_2Tio2 to TiS₂ and on the successive reductionReduction of TiS₂ to Ti. TiO_2Tio2 powder was exposed to CS₂ gas flow at 1073 K, and the conversion to TiS₂ was confirmed. TiS₂ could be reduced to Ti powder either by calciothermic reductionCalciothermic reduction or electrolysis in a CaCl₂ melt. By Ca reductionReduction at 1133 K in CaCl₂ melt, sulfurSulfur concentration decreased to 0.03 mass%S when the amount greater than twice the stoichiometric calcium amount is added. By electrochemical reductionReduction at 1173 K in CaCl₂–CaS melt, S concentration significantly decreased to 0.01 mass%S when four times larger amount of electric charge was supplied.

Calcium oxide is one of the major fluxing agents used for steel refining. Because unreacted CaO remains in slag in most cases, discharged slag is difficult to be recycled smoothly. With the growth of environmental concerns, improving utilization efficiency of CaO is required to reduce the amount of discharged slag and energy consumption. The authors have reported a resource and energy-saving process by using multi-phase flux for dephosphorization. Reaction behavior of phosphorus in multi-phase CaO–FeO_X–SiO₂–P₂O₅ flux system was investigated. Formation mechanism of P₂O₅-rich phases was clarified at the interface between solid CaO or 2CaO·SiO₂ and molten CaO–FeO_x–SiO₂–P₂O₅ slag. Phase relationship and thermodynamic properties of 2CaO·SiO₂-3CaO·P₂O₅ solid solution were observed to confirm the condensation of P₂O₅ in solid phase. Based on these results, reduction of CaO consumption, discharged slag curtailment, and energy-saving effects in the novel refining process by using multi-phase flux were discussed.

Accurate description of complex phase equilibriaPhase equilibria provide the foundations for the improvement of non-ferrousNon-ferrous pyrometallurgical smeltingSmelting and recyclingRecycling processes. Recent advances in microanalysisMicroanalysis and experimentalExperimental techniques enable accurate phase equilibriaPhase equilibria characterisation. Quantitative microanalytical techniques including Electron Probe X-ray MicroanalysisMicroanalysis and Laser Ablation ICP-MS enable the concentrations of major and minor elementsMinor elements present in different phases in samples to be accurately measured providing data that cannot be obtained using bulk chemical analysis techniques. High-temperatureTemperature equilibration experiments coupled with the subsequent analysis of elementary reactions at micro- and macro-scales ensure the attainment of equilibrium conditions, and therefore, ensure true phase equilibriaPhase equilibria information is obtained. Examples of the application of the improved methodology on the investigation of phase equilibriaPhase equilibria of low-order and complex, multi-component gas/slagSlag/matte/metal/solids Cu₂O–PbO–ZnO–Al₂O₃–CaOCao–MgO–FeO–Fe₂O₃–SiO₂–S systems and the distributionDistribution of minor element are provided. The experimentalExperimental study is closely integrated with thermodynamic databaseThermodynamic database development for the above system. Example of implementation of the research outcomes into industrial operations is demonstrated.

Secondary materials, that contain relatively high concentrations of platinum group metals, (PGMs) are treated in copper smelting process. The PGMs lost in the slag is increasing with increasing quantities of scrap treated amount. To determine the portion of the PGMs chemically dissolved and that associated with the mechanically trapped matte in the slag will be a key factor to improve the recovery of those metals. An experimental study was carried out to determine the distribution of palladium between the FeO_x–SiO₂ slag and the liquid Cu₂S–FeS matte at 1573 K and a fixed partial pressure of SO₂ of 0.1 atm. It was found that the distribution ratios are around 10−3 for platinum and palladium. The distribution ratios show a tendency to increase when the grade of matte is increased above 60 mass% Cu. In addition, the solubility of platinum in FeO_x–SiO₂ slag equilibrated with a pure palladium and the Pd-Cu alloy was determined at 1573 K and the range of oxygen partial pressure from 10−9 to 10−7 atm. The solubility of palladium in the slag tends to increase with increasing oxygen partial pressure and activity of CuO_0.5 in the slag.

There is a growing interest in Magnetoelectric (ME) materials in view of both fundamental understanding and novel desirable applications. The application potential for multiferroic materials with the possibility of reversing the magnetization by applying an electric field (or vice versa) is quite promising especially in data storage application. The rare earthRare earth ortho-ferrites (REFeO₃), such as NdFeO3Ndfeo3, have been studied extensively in recent study in the context of discovery of magneto-electric (ME)/multiferroic nature materials. In this paper a potential high temperatureTemperaturerecoveryRecovery of rare earth elementsRare earth elements in the form of REFeO₃ from waste permanent magnetsMagnets using direct oxidationOxidation in air was investigated. It was found that REFeO₃ (NdFeO₃) phase can be separated from the other oxide phases by thermal treatment of NdFeB magnetNdfeb magnet waste at 1100 °C in air atmosphere. The REFeO₃ also found to have different physical characteristic (density) from the other layers and can be separated physically. This paper will include a proposed flowsheetFlowsheet to recover Nd as NdFeO₃ through powder separationSeparation. The technique can be beneficial and favourable for RE recyclingRecycling and recoveryRecovery from waste permanent magnetsMagnets.

EvaporationEvaporation mechanism of S from liquid Fe–C–SFe-C-S alloys at 1873 K was proposed by analyzing available experimentalExperimental data. It has been known that increasing C content in liquid alloy increases activity coefficient of S $$ \left( {f_{\text{S}} } \right) $$fS, and it could raise driving force for the evaporationEvaporation reaction S = S(g). However, experimentalExperimental data of the evaporationEvaporation of S in the Fe–C–S alloys could not be accounted for only by considering the increases of $$ f_{\text{S}} $$fS. In the present study, formation of carbosulfides, CS(g) and CS₂(g), was additionally taken into account in order to explain role of C for the accelerated S evaporationEvaporation. Surface adsorptionSurface adsorption of S was also taken into account, which retards the evaporationEvaporation rate of S. An evaporationEvaporationmodelModel equation was formulated. It can be applied to calculate the evaporationEvaporation rate of S over wider C content (from zero to its saturation to liquid alloy).

BauxiteBauxite is the main raw material used for the production of aluminaAlumina (Al₂O₃) through the well-known commercial Bayer processBayer process. This process has significant challenges such as limitation in using low-grade bauxites as they contain significant amounts of impurities such as Fe, Si, Ti. The Bayer processBayer process residue, which is known as red mudRed mud, is also a global environmental challenge due to huge amount of this low value residue production. An alternative sustainable process with high potential to solve these problems and produce valuable and consumable by-products is a pyrometallurgical-hydrometallurgical process in which the low-grade bauxiteBauxite ore is treated through a smeltingSmelting-reductionReduction process, yielding ironIron alloys and a calcium-aluminate slagSlag. AluminaAlumina is then produced from the slagSlag by hydrometallurgical treatment. In the present work, the reductionReduction of pellets produced from different bauxiteBauxite ores by hydrogenHydrogen is studied and it is shown that complete ironIron oxides reductionReduction is possible. Further smeltingSmelting and smeltingSmelting-aluminothermic reductionReduction of the reduced pellets show that ironIron and siliconSilicon ferroalloys can be produced, in addition to a proper slagSlag for aluminaAluminaextractionExtraction.

In the Bayer processBayer process for aluminaAlumina production, between 2–35% Al₂O₃ is lost with bauxite residueBauxite residue due primarily to incomplete dissolution of aluminiumAluminium-bearing mineralsMinerals during caustic leachingLeaching or the precipitationPrecipitation of sodium alumino-silicate solids. The recoveryRecovery of sodium and aluminiumAluminium from the residue, and particularly from the contained sodium alumino-silicates, is becoming an increasingly critical issue from both an environmental and economic standpoint. LimeLime-soda residue sinteringSintering followed by selective leachingSelective leaching has been proposed as a method to recover sodium and aluminaAlumina. The factors influencing the sinteringSintering mechanisms and kinetics, and the subsequent leachingLeaching have not been well described to date. In this study, the physical and chemical changes taking place during isothermal sinteringSintering of bauxite residueBauxite residue in air, particularly at short reaction times are investigated using scanning electron microscope (SEMSem) and X-ray diffraction (XRD)XRD. The impacts of these changes on the recoveryRecovery of valuable materials are reported.

The pyrometallurgical production and recyclingRecycling of non-ferrous metalsNon-ferrous metals involves the use of complex feed stocks, having a wide range of chemical compositions from sources that include mineral sulphide concentrates, high value obsolete materials and process wastes. The commercial viabilities of these operations hinge on the ability to extract value from these materials. Increasingly, modern computer-based tools are used to describe and predict process outcomes, including mass and heat balances, the partitioning of elements and phase equilibriaPhase equilibria. At the heart of these predictive tools are thermodynamic databases that describe the fundamental chemical properties of a system and all the components present. A comprehensive research program has been established to develop an accurate, self-consistent thermodynamic databaseThermodynamic database describing all gas-slagSlag-matte-metal-speiss-solid phases in the system Cu₂O-PbO-ZnO-Al₂O₃-CaOCao-MgO-FeO-Fe₂O₃-SiO₂-S-(As-Bi-Sb-Sn-Ag-AuAu). The database can be used in conjunction with the FactSage computer platform. The accuracy of the database and its application to industrial practice is demonstrated.

Filtration using Ceramic Foam Filters (CFFs) is a method widely used to separate inclusions from molten aluminium. In the present work, the specific permeability and form drag coefficients of nominal 50 mm thick commercial Al₂O₃-based CFFs, of grades 30, 50, 65 and 80, have been calculated from pressure drop experiments using high (60–500 mm s−1) and low (0.2–10 mm s−1) water velocities. Moreover, 2D axial symmetric Computational Fluid Dynamic (CFD) models have been developed, using COMSOL Multiphysics® to validate the experimental results. The empirically obtained values were defined as global parameters used to model the pressure, as well as the velocity fields in the water pipes and in the CFFs. The modelled pressure drop over the filter thickness for the high water velocity experiments showed < ± 1% deviation from the corresponding experimental results for all CFF grades. Moreover, the developed model also showed good agreement with the experimental results obtained from the low water velocity experiments, where the deviation of the pressure drop for the CFF samples of grade 30, 50 and 65 were ≤ ± 4.6% and for CFF samples of grade 80 ≤ ± 13.4%.

A computational fluid dynamic (CFDCfd) modelModel has been developed using ANSYS Fluent 17.0 to help identify areas of high wear within the refractoryRefractory lining of a secondary leadLeadreverberatory furnaceReverberatory furnace. Once a base case simulationSimulation was validated using data from an operational furnaceFurnace, areas of potentially high refractoryRefractory wear were determined through the calculation of the temperatureTemperature and velocity distributions within the furnaceFurnace and on the hot face of the refractoryRefractory lining. The CFDCfdmodelModel was used to assess whether the predicted areas of high refractoryRefractory wear could be minimized through changes burdenBurden geometry. The results showed that shape of the burdenBurden geometry greatly affected the overall flow patterns and heat transfer within the furnaceFurnace.

Integrated experimentalExperimental and modelling researchPbo-“cu2o”-feo-fe2o3-zno-cao-sio2 program on the phase equilibriaPhase equilibria and development of thermodynamic databases of the leadLead and copperCopper metallurgical gas/ slagSlag-matte-metal-solids systems (PbO-“Cu₂O”-FeO-Fe₂O₃-ZnO-CaOCao-SiO₂) is being undertaken to support improvements in the pyrometallurgical smeltingSmelting and recyclingRecycling processes. This is the first systematic investigation of phase equilibriaPhase equilibria of slagSlag systems in equilibrium with Pb metal, providing information for systems in which copperCopper coexists in slagSlag with leadLead or zincZinc as major components. The experimentalExperimental studies involve high-temperatureTemperature equilibration of synthetic samples, rapid quenching, and measurement of the compositions of equilibrium phases using electron probe X-ray microanalysisMicroanalysis (EPMA). FactSage-based thermodynamic databaseThermodynamic database development is integrated with experimentalExperimental research. Initial thermodynamic assessments are used to identify priority compositions and conditions for experiments, which are planned to provide specific data to assist thermodynamic optimisation. Significant improvement in the accuracy of the phase equilibriaPhase equilibria description is achieved. ContinuousContinuous database improvement and extension to include new elements are targeted. Example of industrial application is given.

SubstitutionSubstitution of pulverized coalCoal injection by solid biocarbonBiocarbon fuel has the potential to achieve substantial reductionReduction in GHG emissions associated with blast furnaceBlast furnace ironmaking. A systematic evaluation was conducted on the performance of solid bio-carbons produced from a single raw biomass source using different pyrolysisPyrolysis technologies. The potential of solid biocarbonBiocarbon in reducing GHG emission of the blast furnaceBlast furnace ironmaking process is strongly influenced by its O/C mass ratio. In order to achieve substantial GHG reductionReduction, it is necessary to replace coalCoal injection by solid biocarbonBiocarbon having a low O/C mass ratio. The pyrolysisPyrolysis technology and conditions employed are key parameters influencing O/C mass ratio of the resultant solid biocarbonBiocarbon. Close collaboration between steelmakers and solid biocarbonBiocarbon producers is critical for producing suitable solid biocarbonBiocarbon fuel to replace pulverized coalCoal injection. A successful partnership should pave the way in achieving substantial reductionReduction in GHG emissions of the blast furnaceBlast furnace ironmaking process.

The rotary kiln-electric furnaceElectric furnace (RKEF) process is the main method for producing ferronickelFerronickel from nickel lateriteNickel lateriteoreOre. However, this process is energy intensive as it involves several high temperatureTemperature steps. Therefore, a novel process is proposed to directly produce ferronickelFerronickel from nickel lateriteNickel lateriteoreOre by semi-molten reductionSemi-molten reduction, which is expected to be realized in a rotary hearth furnaceFurnace (RHF). The RHF process is able to shorten the flow sheet, decrease the reaction temperatureTemperature as well as reduce energyEnergy consumption. In this study, the influence of basicity on reductionReduction of nickel lateriteNickel lateriteoreOre was investigated. The results showed that it is possible to produce the ferronickelFerronickel nugget directly at 1400 °C when the quaternary basicity [(m_CaO + m_MgO)/(m_SiO2 + m_Al2O3)] was fixed at 0.60. Under this experimentalExperimental condition, the grade and the recoveryRecovery ratio of nickelNickel reached 11.53% and 98.59%, and the grade and recoveryRecovery ratio of Fe were 84.16% and 68.72%, respectively.

Chromium has a wide range of applications, including as an alloy addition in various steels and also as a corrosionCorrosion resistance coating. Carbothermal reductionCarbothermal reduction of chromite oreChromite ore (FeCr₂O₄) in a submerged arcSubmerged arcfurnaceFurnace is an important industrial process for extracting chromium, but the energyEnergy consumption is excessive. It is suggested that one area for future research is the low temperatureTemperature carbothermic solid stateSolid statereductionReduction of chromiteChromite to produce an intermediate product, which can subsequently be upgraded to ferrochromiumFerrochromium. In this regard, a thermodynamic modelModel has been developed to investigate this process and the effects of temperatureTemperature, carbon additions and ore composition on the recoveryRecovery of chromium and the grade of the ferrochromiumFerrochromium, have been studied. Further development of the modelModel may allow it to be applied to the simulationSimulation of other processes for the recoveryRecovery of chromium from chromiteChromite ores.

Millions of tons of sludgeSludge from different metallurgical processes are produced worldwide annually, and the environmental impactEnvironmental impact of landfilling these often hazardous sludges stresses the need to understand their role as valuable resources. The current work explores the potential of producing a saleable low-phosphorousPhosphorousferromanganeseFerromanganese alloy by utilizing sludgeSludge from the silicomanganeseSilicomanganese industry together with an ironIron source. The aim of the project is to explore the feasibility and practical challenges related to reductionReduction and dissolution of manganeseManganese and siliconSilicon from the sludgeSludge to liquid metal and slagSlag. Parameters such as ratio of input material as well as the effect of adding limestoneLimestone and coke to the mixture were explored by thermodynamic calculations and adapted experimentally. Results show that a ferromanganeseFerromanganese alloy, in fact, can be formed, while siliconSilicon and calcium forms a complex slagSlag that captures a significant amount of impurities.

In recent years, there have been several efforts to develop binder mixtures for ironIronoreOrepelletizationPelletization. Some efforts have been fruitful, while others have encountered failure. For example, adding corn starchStarch to bentonite is effective, while adding fly ash to bentonite is not. When binders are made with fly ash, a pozzolanic reaction occurs, but no such reaction occurs when bentonite and corn starchStarch are used together. The authors analyzed which binders can be mixed, and which binders will succeed. The authors confirmed this analysis with several laboratory and plant studies. This paper presents this critical analysis, along with various combinations of binders for making IronIron Ore Pellets.

We have designed a high-temperatureTemperatureRamanRamanmicro-furnaceFurnace and cell that is suited for the electrochemical process study of the NO₃− in molten NaNO₃–KNO₃ (fraction of NaNO₃ 50 wt%) salt. During the cycle voltammetry and constant potential electrolysis process, the RamanRaman laser beam was focused near the electrode; subsequently, the RamanRaman spectra are obtained and the reductionReduction process of NO₃− is analyzed. In the CV cathodic scan process, the new peak attributed to the $$ \upnu_{1} $$ν1 mode of NO₂− emerges, and the peaks assigned to superoxide ions (O₂−) and peroxide ions (O₂2−) are not found. In the constant electrolysis process, the peaks at 1130 and 800 cm−1 appear when the potentials are between −2.0 V and −3.2 V (vs. Pt). The results show that when the NO₃− is reduced in molten the NaNO₃–KNO₃ mixtures, the reductionReduction product O2− cannot stably exist, and O2− will react with NO₃− to form of superoxide ions (O₂−) and peroxide ions (O₂2−).

FerromanganeseFerromanganese is a ferroalloyFerroalloy with high manganeseManganese content which finds many uses for example as deoxidizer in steelmakingSteelmaking industry. However, there is very little data on the dissolution rateDissolution rate of carbonaceous materials in Mn containing metals. In this paper, the kineticKinetic analysis of carburizationCarburization reactions is investigated for Mn–Fe alloys. Dissolution rateDissolution rate of graphite in pure ironIron and four different alloys with 10 wt%, 40 wt%, 60 wt% and 85 wt% manganeseManganese at 1823 K was studied. Results showed that the dissolution rateDissolution rate of carbon from graphite increased with increasing time for all alloys. The dissolution rateDissolution rate constant increased with the increasing manganeseManganese content from 6.5 × 10−3 cm/s for 0%Mn to 23.6 × 10−3 cm/s for 85%Mn.

IronIron containing leachLeach residues like jarositeJarosite and goethite from electrolytic zincZinc production contain many valuable metalsValuable metals and harmful substances. These metals and substances should be removed in order to obtain an acceptable, stable and reusable product, and maximize economic feasibility as well as minimize environmental footprint. In this work, the processing of jarositeJarositeleachLeach residue was studied in laboratory scale experiments under oxidizing and reducing conditions at high temperatures. First, the pretreated material was melted and oxidized to produce a melt of metal oxides. Second, the oxide melt was reduced in COCo–CO₂Co atmosphere. Target after the reductionReduction step was to obtain a clean slagSlag and a liquid metal or speiss phase that collects the valuable metalsValuable metals, such as silverSilver. The kinetics of the thermal processingThermal processing were studied for determining optimal times and conditions for the aforementioned process steps. The preliminary results show that the process is thermodynamically feasible, and the desired phases can be obtained in the experimentalExperimental conditions investigated.

Depleting copperCopper resources and advancing technologies have challenged industries to develop more viable, adaptable and cost efficient processes using also secondary raw materials in copperCopper production. This study is targeting to that goal by dynamic modelling of flow and heat transfer coupled with chemical kinetics in an industrial scale flash smeltingFlash smeltingfurnaceFurnace settler using commercial CFDCFD software ANSYS Fluent. First, different physical phenomena occurring inside the settler, for example, settling and separationSeparation of the matte/slagSlag phases, and heat transfer between slagSlag/matte phases and settler walls are studied. Secondly, reaction kinetics between matte and slagSlag, and between slagSlag/matte and settler walls, and impurity element distributionElement distribution will be studied. This would also include phase changes phenomena due to these reactions and the flow of the reaction gases inside the settler. Settling of polydispersed droplets, their coagulation, breakage, and WEEEWEEE particle behavior are further targets of the modelling work.

A broad spectrum of tantalum containing input materials can be processed for the production of synthetic tantalum concentrate (“SynCon”). The use of these low grade substances offers a secure alternative to mining of coltan in Central Africa. SynCon is produced in a multi-stage pyrometallurgical process, wherefore the melting behaviour of slags presents an important factor especially regarding the energy consumption and its optimisation. The characteristics of a slag comprising mostly Al₂O₃, CaO, SiO₂Sio₂ and MgO are influenced by the amount of other oxidic constituents which enfolds the main focus of this study. A hot stage microscope serves for the investigation of the slag behaviour in a temperature range from 1000 to 1600 °C under reducing atmosphere (CO/CO₂ gas). The experimental results are compared with thermodynamic calculations (FactSage) to get a better understanding of the process.

Relentless increases in demand for nickelNickel and vanadiumVanadium for uses such as steelmakingSteelmaking, catalysts and battery materials, plus the growing financial and environmental costs of their primary extractionExtraction, have led to much interest in potential secondary sources of these metals. The presence of such metals in heavy fuel oils, bitumen and related materials offers both opportunities and challenges for potential extractionExtraction methods, especially with the growing production and importance of metal-rich fossil fuels around the world. For several decades, Tetronics’ DC plasma smeltingPlasma smelting technology has been used for the recoveryRecovery of metals such as nickelNickel and chromium from stainless steelSteel melt dusts and other wastes in compact, environmentally-friendly and efficient plants. This paper explores the suitability of DC plasma smeltingPlasma smelting as part of a wider flowsheetFlowsheet with feed preparation and aluminothermic reductionReduction techniques for smaller-scale extractionExtraction operations based on this important niche secondary sourceSecondary source of these key metals.

Iron segregationIron segregation is pre-dated by copperCopper and nickelNickel segregation processes for which the experimentalExperimental methodology and reaction chemistry were established. The accepted reaction sequence for segregation involves the generation of hydrogenHydrogenchlorideChloride, the chloridization and volatilization of the metal chlorideChloride, and precipitationPrecipitation of the metal from the metal chlorideChloride in the vicinity of carbon. Iron segregationIron segregationroastingSegregation roasting offers a potential extractionExtraction solution for processing oxide deposits with complex mineralogyMineralogy or waste streams such as Minette-type ironIron deposits, nickelNickel laterites, ilmeniteIlmenite, red mudRed mud, electric arc furnaceElectric arc furnace(EAF) dust, Furnacemill scaleMill scale and slagSlag. After subsequent magnetic separationMagnetic separation, one is left withSeparation a high grade metallic ironIron powder which can be marketed for powder metallurgy or briquetted to serve as a direct reduced ironIron (DRIDirect Reduced Iron (DRI)) product. The non-magnetic product is typically concentrated oxides including rutile, aluminaAlumina, or oxides of V, P, and rare earthsRare earths, etc. that may be economically recoverable with subsequent processing. While operating conditions vary for different metals, they share the requirements of an elevated operating temperatureTemperature and a mixture of oxide oreOre, carbonaceous additive and a chlorideChloride additive in varying amounts all in a closed reactor to allow for reducing conditions and contain the volatile chlorides. This process is then followed by some form of physical separationSeparation. Testwork performed by the authors shows promising results that may aid in future development of the process. Segregation roastingSegregation roasting of ironIron will likely never displace traditional beneficiation and ironmaking technologies; however, it has great potential in niche markets where traditional technologies have failed or current technologies generate substantial waste.

Microwave processing is a relatively new technologyNew technology that has been successfully applied in a number of industries. However, in the field of metal extractionMetal extraction, there is a paucity of success, despite considerable hype in the early years. Increased reaction rates, lowered reaction temperatures and higher energyEnergy efficiencies were some of the advantages claimed. Even with over almost two decades of research and some pilot plantPilot plant studies, microwave metal extractionMetal extraction remains essentially a laboratory technique. In this paper, the research performed over the last few decades will be reviewed and some reasons for the lack of success in developing microwave metal extractionMetal extraction processes will be discussed. Based on the knowledge gained from these experiences, a more informed view of microwave heating can leadLead to the realization that there is still some untapped potential for this heating technique in metal extractionMetal extraction processes.

AluminumAluminum and copperCopper are large volume metals in electronic appliances, while tin and indiumIndium exist as common minor elementsMinor elements. All of these non-ferrous metalsNon-ferrous metals are aimed to be separated and recycled from the end-of-life electronics into non-ferrousNon-ferrous scrap fraction(s), and further through pyrometallurgical and/or hydrometallurgical processesHydrometallurgical processes to pure metals. Depending on the mechanical pre-treatment processes, aluminumAluminum and copperCopperliberationLiberation from each other varies. This study focuses on the influence of aluminaAlumina on indiumIndium and tin distributions between copperCopper alloy and iron silicateIron silicate slags with 0, 9 and ~16 wt% of Al₂O₃. The experiments were executed with an equilibration-quenching-EPMA technique in an oxygen pressure range of 10−10–10−5 atm at 1300 ℃. The metal-slagSlagdistributionDistribution coefficient of indiumIndium remains constant as a function of aluminaAlumina in slagSlag, while that of tin increases. Therefore, aluminumAluminum in feed or aluminaAlumina addition to the slagSlag improves the recoveryRecovery of tin into copperCopper. Nevertheless, oxygen pressure has clearly more significant influence on the behavior of both the metals in the smeltingSmelting conditions.

For better understanding and maximal value utilization of the WEEEWeeesmeltingSmelting process, the behavior and distributionDistribution of different trace elements must be known. In this study, the behavior of nickelNickel as a trace element was studied in an equilibrium system with metallic copperCopper—spinel saturated iron silicateIron silicateslagSlag (with 3 wt-% K₂O)—ironIron aluminous spinel—gas. The experiments were conducted in aluminaAlumina crucibles at 1300 °C, in oxygen pressure range of 10−10–10−5 atm. A time series of 15–60 min experiments was also conducted for investigating the formation rate of the primary spinel phase in the system. The results show that the distributionDistribution coefficient of nickelNickel between metallic copperCopper and liquid slagSlag changes from approximately 70 to 0.4 along the increasing oxygen pressure range. In addition, a significant part of the nickelNickel deports into the spinel phase. The spinel formation was investigated based on composition analysis results and visual observations from SEMSem-images.

In Europe, 50% of the copperCopper originates from recyclingRecycling. High-Cu containing scraps are regularly rich in impurities like Fe, Ni, Sn and Pb. Many high-Cu containing scraps are fed directly into anode-furnaceFurnacecastingCasting installations or furnaces with limited refiningRefining capability. The impurities levels of the anodes produced in these processes should however remain acceptable for further electro-refiningRefining.The distributionDistribution of Sn between copperCopper and slagSlag has been investigated for conditions relevant to copper convertingCopper converting. Unlike previous studies, this work focuses on the behavior of Sn relevant to fire refiningRefining conditions, which are essential for anode refineries.In this study, liquid Cu–1Sn and CuO_x–FeO_y–SiO₂slagSlag, with CaOCaO additions, were equilibrated at 1300 °C in vacuum sealed SiO₂ ampoules. After metal–slagSlag equilibration, the samples were quenched in water. The composition of the slagSlag and Cu metal was investigated with Electron Probe X-ray MicroanalysisMicroanalysis. The distributionDistribution coefficients of Sn between slagSlag and Cu metal were determined as a function of slagSlag composition.

The efficiencyEfficiency in production of manganeseManganese ferroalloys is dependent on the gaseous reductionGaseous reduction of the higher manganeseManganese oxides in the ores used as raw materials. The materials, descending in the furnaceFurnace, will meet the furnaceFurnace gas that contains significant amounts of CO(g) and reduce in subsequent steps, the last step being reductionReduction of Mn₃O₄ to MnO. This step may to varying extent occur at temperatures exceeding 800 °C, i.e. in the active region of the Boudouard reaction. The gas reductionReduction of Assmang and Comilog manganeseManganese ores were investigated in CO-CO₂-atmosphere at temperatures up to 1000 °C. It was seen that decreasing ore size correlates to a lower reductionReductiontemperatureTemperature and increasing reductionReduction rate. Similar effect was observed with increasing COCo-content in the gas atmosphere. Further, it was found that Comilog ore obtained a complete prereductionPrereduction at 600 °C, whereas reductionReduction of Assmang ore was not complete at 800 °C for the majority of the experiments.

The proper controlControl of slagSlag composition is a dominant factor affecting yield of ironIron as well as dephosphorizationDephosphorizationefficiencyEfficiency in an electric arc furnaceElectric arc furnace (EAF) operation. Moreover, thermophysical properties of slags such as viscosityViscosity are strongly affected by the changes in slagSlag composition. Slag foamingSlag foaming, which is also a function of viscosityViscosity, is directly connected with the yield of ironIron and thus optimum slagSlag chemistry are highly required in view of thermodynamicsThermodynamics and physical properties. Therefore, we analyzed the slagSlag composition in commercial melt shop (70 ton EAF) with the aim of higher yield of ironIron as well as higher dephosphorizationDephosphorization during EAF process.

An innovative leadLeadrecyclingRecycling process from scrap leadLead-acid battery paste is presented. The novelty in the process is avoiding SO₂ generation and emission by using reductive sulfurSulfur-fixing technique. IronIron-bearing secondary wastes produced from metallurgical industry were utilized as sulfur-fixing agentSulfur-fixing agent to capture sulfurSulfur in the form of FeS (s) instead of generation of SO₂ (g). Na₂CO₃Co molten salt was added to the smeltingSmelting system to speed the reactions and improve valuable metalsValuable metals’ recoveryRecovery and sulfurSulfur-fixation efficiencyEfficiency. Furthermore, this process can simultaneously coCo-treat various leadLead and iron-bearing wastesIron-bearing wastes. At the same time, some precious metalsPrecious metals, such as AuAu and Ag, contained in iron-bearing wastesIron-bearing wastes can be recovered. The feasibility and reliability of this process was investigated thermodynamically and experimentally with the help of HSC 9.0 database and XRDXRD and SEMSem-EDSEds analysis. A possible reaction mechanismReaction mechanism and path in PbSO₄–Fe₂O₃–Na₂CO₃Co–C smeltingSmeltingsystem wasSo2 (g) emission free also clarified.

The viscosityViscosity is one of the most critical properties of slags and thus its influence on the physicochemical phenomena in metallurgical processes has been issued for last decades. The viscosityViscosity of ferrous- and non-ferrousNon-ferrous metallurgical slags can be understood via structural investigation with spectroscopic methodologies including x-ray photoelectron spectroscopySpectroscopy, infrared- and Raman spectroscopyRaman spectroscopy, and solid stateSolid state nuclear magnetic resonance spectroscopySpectroscopy, etc. Therefore, the reaction kinetics such as desulfurization in ladle metallurgical furnaceFurnace, reductionReduction of FeO and MnO in electric arc furnaceElectric arc furnace is strongly dependent on the viscosityViscosity of the slags. The rates of oxide (inclusion and refractoryRefractory) dissolution into the slags and fluxes are governed by the viscosityViscosity. Alternatively, the structure of aluminosilicate melts also affects the thermochemical properties such as sulfideSulfide capacity, etc. These diverse applications of the viscosityViscosity-structure relationship to ferrous- and non-ferrousNon-ferrous metallurgical processes were reviewed.

Current methods for producing low-carbon manganeseManganese alloying materials for the steelSteel industry are energyEnergy intensive and costly. To enable wider implementation of high Mn steelSteel alloys, a novel solid-state Mn ore reductionReduction strategy is therefore being investigated. This solid-state process, modelled on existing Direct Reduced IronIron technology, employs a methaneMethane-containing atmosphere to reduce Mn ore pellets to a metal carbide. These pellets may then be smelted, yielding a Mn-rich master alloy. It is well established that CH₄ is a suitable reductantReductant for Mn ore powders; however, the reductionReduction behaviour of industrially relevant Mn ore pellets by CH₄ is poorly understood. The present work reports the results of an investigation undertaken to address this knowledge gap. The results of this study highlight the significantly different reductionReduction behaviour exhibited by the Mn ore pellets relative to the ore powder under similar conditions and suggest that the diffusion of CH₄ into the pellet interior is the limiting factor in achieving complete reductionReduction.

MethaneMethane is increasingly considered as a promising reductantReductant for metal oxides, including chromiteChromite. To assess the possibilities of such reductionReduction route, the gas-solid reactions between Ar–CH₄–H₂ gas mixtures and synthetic chromites are studied between 950 and 1050 °C. The influence of Mg and Al additions on the reductionReduction-caburization of (Fe,Mg)(Cr,Al)₂O₄ solid solution is investigated thermodynamically, structurally and kinetically. The product phases are examined by x-ray diffraction (XRD)XRD, scanning electron microscopy (SEM)SEM, and electron probe microanalysisMicroanalysis (EPMA). The reaction rate is derived from real-time exhaust gas measurements and post-reaction product analyses such as oxygen analysis. KineticKinetic models are proposed based on the product phase morphologies and confronted with the empirical data.

Filtration of liquid aluminium is widely used in the industry for the removal of inclusions, and Ceramic Foam Filters (CFFs) are often the filtration media of choice. It is known that PH3 (phosphine) can be released from used phosphate bonded CFFs when in contact with water. Additionally, there is a need of an improved understanding of the thermal stability and the chemical reactivity of these types of filters, as there is limited information available in the public domain. In the present preliminary study, three CFFs, i.e. Substrate 1–3, with varying AlPO4 (aluminium phosphate) content were studied under controlled conditions. Samples of the substrates, as produced and in contact with 5N pure aluminium, were heat-treated in a vacuum induction furnace at 850 °C and 1300 °C, as well as thermally studied at 850 °C using a Differential Scanning Colorimeter connected to a Thermogravimetric Analyser (DSC-TG). All tests were performed under an inert atmosphere of argon (Ar). Mass changes of ~0.001 % were registered for the pure substrates, and 0.003-0.10 % when in contact with aluminium. In the latter case, diffusion of P (phosphorous) from the bulk of the substrate to the interface was established to have taken place. A colour change, from white to orange/brown, was also observed at the interface, which is a clear sign that a chemical reaction has taken place. As a result, the thermal stability of the substrates can be questioned under present conditions.

The close proximity of cobaltCobalt and nickelNickel on the Periodic Table and their frequent occurrence together in nature means that their separationSeparation in primary hydrometallurgical flowsheets is not only often necessary, but requires the use of innovative chemistry to achieve high selectivitySelectivity. Today, increasingly stringent demands for the high-purity cobaltCobalt and nickelNickel salts required for battery applications in consumer electronics, electric vehicles, and solar applications are again challenging the state of the art. The evolution of cobaltCobalt–nickelNickel separations is traced from the basic precipitationPrecipitation technologies employed in 1960s, through commissioning of the first cobaltCobaltsolvent-extractionExtraction plant in South Africa in 1974, to the commercialisation of organophosphinic-acid extractants (which provided a step-change improvement in selectivitySelectivity) and their eventual widespread use in the 1980s and ’90s. This was followed later by their sulphur analogue, which enabled different possibilities for laterite processing in the new millennium. Separations in chlorideChloridemediaMedia, which take advantage of the different speciation chemistries, and nickelNickelextractionExtraction by oximes in ammoniacal systems are also discussed. More recently, chelating and solvent-impregnated resins have added further dimensions to the possibilities for flowsheetFlowsheet design and enabled higher purity products to be attained from both primary and secondary sources. Selected case studies and flowsheets are described.

One of Society’s major concerns with hydrometallurgical processing is the large amount of water that is quintessential to its nature. This is especially troubling in arid areas, where the population struggles to procure potable water for their daily needs. For that reason, it has become our responsibility to conceive, design and implement processing schemes that not only use as little water as possible, but recycle streams within the plant itself and minimize waste that exits its perimeter. With this in mind, the conference will center on the importance of selecting the appropriate chemical systems and integrating material balances to avoid reagent overkill and to detect impurity accumulation. The three “R’s” (reuse, recycle and recoveryRecovery) of aqueous solutions within the processes are emphasized. Examples of processes for the recoveryRecovery of leadLead, copperCopper, precious and PG metals from mineralsMinerals and waste materials will be presented.

Brine leachingLeaching of a TSLTSL processed zinc-plant residue (ZPR), containing 83.3% anglesiteAnglesite, has been investigated for lead recoveryLead recoveryRecovery. A prior treatment of ZPR in acid solution did not show any significant effect of acid concentration in zinc dissolution. The study reveals that the solubilitySolubility limits of PbCl₂ is as an important factor with respect to the brine concentration and pulp density in lixiviant. The dissociated sulfate ions hinder the formation of PbCl₂ on prolong leachingLeaching (above 60 min), while exhibiting the reverse solubilitySolubility of leadLead as PbSO₄. A 3-step leachingLeaching process could yield >92% leachingLeachingefficiencyEfficiency when the parameters were maintained as: 10% pulp density in a 250 g/L NaCl solution, 80 °C temperature, and 60 min time. This leaves the insoluble ferrite, sulfides and oxy-sulfates of zincZinc and leadLead in the final residue as revealed by the XRDXRDcharacterizationCharacterization.

Radioactive wastewaters from nuclear source of electrical energy production need to be treated and disposed of properly. Sr, Ca, Mg and Ba are common elements in this effluent, which can cause incrustation in process equipments and being unsafe to human health (90Sr). Fixation of CO₂ can be applied to remove the ions mentioned before and to provide a solution where CO₂ is sequestered and the deleterious elements precipitated, becoming one of the possible steps to reuse the water into the process. Moreover, removal of several metals from distinct wastewater has been evaluated using bone char through adsorption. The chemical similarity between calcium and strontium makes the exchange of these two metals favorable in the hydroxyapatite structure contained in bone char. This paper evaluated the combined action of precipitation and adsorption process with injection of CO₂ and bone char addition in simulated nuclear wastewater. Removal levels of 89.0% (Sr) and 83.3% (Ca) were obtained in the combined process. The presence of bone char as seed increased the precipitation kinetics, allowing a Sr removal of 85.2% in five minutes, higher than 75.3% obtained in absence of seeds. However, removal of 91.6% (Sr) and 89.8% (Ca) were obtained in absence of seeds at 24 h. Analysis of solids have evidenced that CO₂ was consumed to precipitate the metals as carbonates, since the hydroxides are formed at higher pH’s.

A crystalline polyferric sulfate (PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions under atmospheric conditions. The morphology, structure, composition and specific surface area (SSA) and adsorptive efficacy to As (III) of the adsorbent were characterized by SEM/EDS and TEM images, XRD patterns, FT-IR spectra, BET SSA analyses and adsorption experiments. The adsorbent presents as morphology of near-spherical aggregate and good crystallinity. A small amount of goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased the SSA of the aggregates. The absorbent with co-precipitation of goethite showed good adsorption to As(III) and good filtering performance in the high As(III)-content solution of 10–100 mg/L under acidic, neutral and alkaline conditions (pH 2.09–9.01), and its maximal adsorption capacity and adsorption efficiency were 7911 μg/g and 96% separately. After Adsorption, the stability of the absorbents adsorbing As(III) were evaluated by TCLP tests, and the results indicated that the absorbents adsorbing As(III) were extremely stable, and the concentration of arsenic in all leaching solutions were less than 0.01 mg/L.

There are a variety of choices of materials for mineral extraction processing. Traditionally, end users have used metallic piping for fluid handling and little is known about the advantages (or limitations) of non-metallic piping systems. This presentation will review custom FRP pipe systems and their use in severe corrosive and erosive process streams. These systems can be designed to various pressure and temperature ratings and different components (such as resin and glass type) can be varied to suit the process conditions.

In this research assisted leaching of chalcopyrite using sodium peroxodisulfate was studied. Electrochemical techniques such as Tafel analysis and electrochemical impedance spectroscopy (EIS) were used to investigate the surface reactions of a chalcopyrite electrode in the presence and absence of Na₂S₂O₈. According to the results, addition of sodium peroxodisulfate increases the current exchange of the corrosion process and prevents the formation of a passive layer on the surface of the electrode. EIS tests show the trans-passive dissolution of the passive layer on the chalcopyrite electrode in presence of Na₂S₂O₈. Equivalent electrochemical circuits were modeled for Na₂S₂O₈-free and -containing solutions and the model parameters were compared to determine the effect of S₂O₈2− on chalcopyrite dissolution. Copper dissolution from pure chalcopyrite mineral and chalcopyrite concentrate was carried out using 15 g/L sulfuric acid solution with and without Na₂S₂O₈. Simultaneous presence of 10 g/L ferric ion and 40 g/L peroxodisulfate salt results in about 40 and 18% of Cu extraction from chalcopyrite concentrate and pure chalcopyrite mineral, after 96 h, respectively.

This study investigated leaching kinetics by alternative lixiviants for copper leaching from chalcopyrite (CuFeS₂), the most abundant copper resource in the world. As a refractory sulfide mineral, chalcopyrite shows low copper extraction due to passivation on chalcopyrite surface. Also, decrease of copper grade with high portion chalcopyrite requires the alternative leaching procedure to increase copper recovery. Therefore, alternative lixiviants such as sulfurous acid and methanesulfonic acid (MSA) were tested for both concentrate and low grade ore to enhance copper extraction. Also, an oxidant, hydrogen peroxide, was compared to ferric to find out the improvement of leaching kinetic. In concentrate leaching tests, 30 g/L MSA showed the highest copper extraction (47%), compared to other lixiviants at 75 °C. Periodical H₂O₂ addition enhanced copper extraction, and above 90% of copper extraction was observed within 96 h by periodical addition of 0.6% H₂O₂ at 75 °C. The activation energy of chalcopyrite leaching by MSA and H₂O₂ achieved 40 kJ/mol, which is chemical reaction control. The results of low grade ore leaching tests indicates that no significant difference among lixiviants (H₂SO₄, H₂SO₃ and MSA) with ferric was observed, all of which achieved around 37% within 24 h at room temperature. However, significant increase of copper extraction (>80%) was observed at both 20 g/L MSA and 10 g/L H₂SO₄ conditions by the addition of 10% H₂O₂.

Sulphidic copper concentrates are generally processed by pyrometallurgical means; while oxidative pressure leach processing of such materials has been shown to be technically feasible, there has traditionally been little incentive to choose this route in favour of a smelting option. However, for concentrates with elevated arsenic levels, oxidative pressure leaching offers distinct advantages, as smelter air emission standards and restrictions on concentrate importation have tightened. The current state of pressure leach technology allows for high copper extractions from arsenical copper concentrates, while producing an environmentally stable process residue, without atmospheric emissions of sulphur dioxide or arsenic. In its studies on pressure leaching of copper concentrates, Sherritt has shown that arsenical feed materials can be converted into environmentally stable residues, with excellent copper extractions. The results of recent batch and pilot plant test work are discussed, including the deportments of copper, arsenic and precious metals.

This paper illustrates sustainabilitySustainability considerations in copperCopperhydrometallurgyHydrometallurgy using examples of practices at ASARCO LLC, an integrated U.S. primary copperCopper producer. Using the classic Brundtland Commission development of sustainable developmentSustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copperCopperhydrometallurgical processesHydrometallurgical processes can be sustainable. The examples used to illustrate sustainable developmentSustainable development and related concepts include: water conservation opportunities in milling and leachingLeaching operations; implementing green chemistryGreen chemistry and promoting product stewardshipProduct stewardship in the electrorefiningElectrorefining of copperCopper.

Ethylene glycolEthylene glycol additions to aqueous acid solutions for leachingLeachingcopperCopper sulfides increase both copperCopper and ironIron extractions compared to a conventional sulfuric acidSulfuric acidleachLeach with hydrogen peroxideHydrogen peroxide (H₂O₂). The role of ethylene glycolEthylene glycol is to prevent peroxide destruction, which normally occurs in solutions that contain both cupric and ferric ions. However, despite this improvement, ethylene glycolEthylene glycol and sulfuric acidSulfuric acid concentrations must be high (3.5 M and 0.7 M, respectively) to obtain satisfactory conversion levels at room temperatureTemperature. In the present investigation, EDTAEdta was used as an additive to complex the cupric and ferrous ions, lowering the requirements of ethylene glycolEthylene glycol and H₂SO₄ to 0.11 M and 0.007 M, respectively, while minimizing oxidant decomposition. The experimentalExperimental results for a mainly chalcopyriteChalcopyrite, copperCopper concentrate showed complete copper extractionCopper extraction in 24 h at room temperatureTemperature, with the stoichiometric quantity of EDTAEdta for the copperCopper and ironIron dissolved. Tests using seawater were equally as successful.

The aim of this research was to develop a copper recovery process from mine tailings (0.34%Cu) using flotation followed by high-pressure oxidative leaching (HPOL) and solvent extraction. The results of HPOL using the concentrate of mine tailings obtained by flotation under the optimal conditions of the previous study shown that an efficient copper dissolution of 94.4% was achieved in an H₂O media, while the copper concentration of PLS reached to be 2.9 g/L. The solvent extraction of PLS obtained from the optimal HPOL showed that 91.3% copper was recovered in stripped solution under the determined optimum conditions, in which the copper concentration achieved to be 44.8 g/L. Finally, a proposed copper recovery process from the concentrate of mine tailings was developed by combination of HPOL and solvent extraction, while a total copper recovery of 86% was achieved.

James DouglasJames douglas became known in the nineteenth century for two reasons fundamental to his mining career: (1) his experimentalExperimental work with copperCopperhydrometallurgyHydrometallurgy, and (2) his grasp of the idea that the quantity of copperCopperoreOre matters more than the quality. On the first reason, there is a moment for any technology that’s critically important—when it moves from an area of scientific interest to one that companies are founded on. This paper examines the original 1869 Hunt and Douglas CopperCopper Process in the context of science and engineering as they were in the 1860 and 1870s. It was a “humid” process, developed at Quebec’s Harvey Hill Mine. Chemically, the Hunt and Douglas vat leachingLeaching process succeeded, but not the original companies using it. On Douglas’ understanding of oreOre quality versus quantity, luck had it that the first company to field test the Hunt and Douglas CopperCopper Process was in ChileChile. The Hunt and Douglas patent made that transition from experimentalExperimentalmodelModel to operational plant in 1870 when the Compañia de Minas de la Invernada was organized in Valparaíso. As a joint-stock company, Invernada spread the risk of investing in the revolutionary, but untested, Hunt and Douglas Process. The company brought Douglas to ChileChile as a consultant in 1871. His experience with hydrometallurgyHydrometallurgy, combined with what he learned about the copperCopper business while in ChileChile, set him off on a career in metal mining that both surprised Douglas and made him wealthy.

Building on work completed in earlier papers, the current paper presents a techno-economic evaluation of two recently demonstrated technologies for treatment of arsenicArsenic containing refractoryRefractorygoldGold concentrates. Using defined project parameters and inputs, the authors compare capital and operating cost estimates for pressure oxidationPressure oxidation (POx), and the Albion Process™. The paper incorporates data now publicly available from the Albion Process™ plant, which has operated at the GeoProMining GoldGold (GPM GoldGold) project in Armenia since 2014, as well as recent POx circuits.

Mantoverde is a heapHeapleachLeach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 tonnes of copperCopper per year and 5.4 million tonnes of ore per year. CopperCopper production was steadily increased reaching a maximum of 62,239 tonnes in 2012 for an ore throughput of 10,5 million tonnes. In order to get these production and throughput rates, a number of changes have been made in the metallurgical parameters of the plant operation since the start up, among them particle size, heapHeap height, acid addition distributionDistribution in curingCuring and leachingLeaching solution, leachLeach cycles and pad type. Most of the modifications have been implemented after carrying out extensive column test workColumn test work programs. The modifications implemented and the results obtained, as well as the test work programs carried out, are discussed in this paper.

The effect of aeration on chalcocite heap leaching was studied by analyzing the historical data from two chalcocite heap leach pads located in Chile, one with aeration and the other without aeration. The data showed that the copper leaching kinetics of the aerated heap was greater than that of the unaerated heap within a certain leaching period, after which there was no effect of aeration on the copper leaching kinetics. The total acid consumption per ton of ore processed was higher in the case of aeration, which was supported by the higher pH of the PLS. But the net acid consumption per ton of copper produced was the same in the two cases. Approximately 5% of the total iron added to the unaerated heap was precipitated inside the heap. In contrast, there was no net iron precipitation or generation inside the aerated heap. Bacteria activities were thought to occur even in the unaerated heap, but the extent was much less than in the aerated heap. Given the importance of forced aeration in chalcocite heap bioleaching, mathematical modelling will be applied in the future work to assist the optimization of the aeration system design.

In heap leaching, the oxidative dissolution of value minerals encapsulated deep within large particles cannot be fully understood on the basis of the bulk solution conditions relative to variable solution conditions near the mineral surface. In the present study, the diffusion of the oxidising species through inner particle pores is simulated in a model apparatus that separates an inert platinum electrode under controlled reduction potential from the bulk solution through narrow pores of varying length. The Cu-NH₃ system was selected as a model system and Cu(II)/Cu(I) as the redox couple of interest. Platinum probes inserted in the pores allowed the measurement of varying redox potentials along the pore length. Results showed that in a 10 mm pore, there exists a narrow (0.5 mm) zone near the reduction surface that is depleted of the oxidant and in which its supply is strongly diffusion limited, even if it is in abundance in the bulk solution. The consistent presence of this narrow diffusion region across all experimental results indicated that the transportation of the reduced species away from the reaction surface had the most significant influence on the potential variations within the pore. This was further supported by the minimal effect of varying concentrations of both Cu(II) and dissolved oxygen on the solution potential within this region.

Ferric iron removal from the nickel electrolyte at Glencore Nikkelverk AS in Kristiansand, Norway, is achieved by precipitation of iron hydroxide followed by filtration, and it is desirable to improve filtration properties of the precipitated iron hydroxide in order to decrease the filtration time. The effect of increasing the residence time from the current 45 min to 75 min and temperature from 65 °C to 90 °C on the filtration properties of the precipitated iron hydroxide (akaganéite) was studied by simulating the industrial process conditions in a continuous reactor setup operating at steady state, using ferrous-containing process solution as feed material. It was possible to decrease the filter cake resistance by both increasing residence time and temperature, but temperature gave the most pronounced effect and reduced the filter cake resistance by one order of magnitude.

Iron-free titanium oxycarbonitride (TiO_xC_yN_z) is a promising feedstock for production of titanium tetrachloride (TiCl₄) at low temperatures. In this study, the effects of leaching variables such as temperature, time, particle size of staring material and concentration of the leaching solutions were evaluated on iron removal from nitrided Malaysian ilmenite by Becher process. The nitrided ilmenite was prepared by isothermal reduction with graphite at 1200 °C for 3 h in H₂-N₂ atmosphere. The aerated leaching experiments were conducted at 50–90 °C with addition of 0.3–2.0 wt% of NH₄Cl catalyst. The highest extent of iron removal (X_Fe) was obtained at about 96.2% for the sample leached at 90 °C for 7 h with 2.0 wt% NH₄Cl. The iron concentrate and titanium oxycarbonitride product were characterized by ICP-OES, XRD, XRF and SEM-EDX analyses. The results indicated that the aeration leaching process was a successful route to prepare low-iron titanium oxycarbonitride.

As an industry with major potential impacts (both good and bad) on water resources and due to the rising costs of process water, the mining and metallurgical processing industry has a key responsibility to contribute to the overall goal of preserving both the quantity and quality of water available within the watersheds they operate in. As we plan for new and existing mining and metallurgical projects, we need to consider a hierarchy of options to minimize our impact within the watersheds we operate; keeping clean water clean by diverting around our operations; reduction in the amount of water we use; reuse of water wherever possible, and improvements to water quality for recycling and/or release to environment. Technology is needed to treat water to improve its quality for reuse or release to the original watershed. While lime precipitation followed by sulfide polishing is effective for removal of most of the metals, it does little or nothing to remove ammonium ions and anions such as chloride, nitrate, molybdate, arsenate and selenite/selenite. Regulations on sulfate limits in treated discharge water has drawn close attention to the treatment of acid mine drainage (AMD). Management of brine and salt disposal is also posing a problem due to strict regulations and cost of disposal. This paper will: (a) address issues associated with managing water with the objective of maintaining water sheds—status quo-during and after operation (b) discuss potential technologies for advanced water treatment plants.

Scorodite (FeAsO₄·2H₂O) is suitable mineral carrier for immobilization of arsenic-rich wastes. Its stability is, however, highly pH dependent (typically at 4 ≤ pH ≤ 7) and satisfactory only under oxic disposal conditions. In this work an encapsulation process using mineralized gels of aluminum hydroxy-oxides is developed to enhance the stability of scorodite under wider pH and redox potential range conditions. The encapsulation involves blending and ageing of synthetic scorodite produced by McGill’s atmospheric scorodite process with aluminum hydroxyl gels derived from controlled hydrolysis of aluminum salts. The amorphous hydrolyzed Al-gel encapsulates the scorodite particles, which upon short-term aging transforms into crystalline Al(OH)₃/AlOOH mineral phases providing a robust protection microscopic barrier. Long-term stability testing demonstrates the encapsulation system to be highly effective in suppressing arsenic release under either oxic or anoxic (100 mV < E_h < 600 mV) potential and neutral-alkaline pH (7 ≤ pH ≤ 9) ranges.

In recent years, the removal of arsenic from different types of high arsenic containing materials produced in nonferrous metallurgical processes have been experimentally studied in the complex materials processing research group from Central South University. These materials include arsenic and antimony bearing flue dust, arsenic sulfide residue and arsenate bearing flue dust. The separation of arsenic from other valuable metals was carried out hydrometallurgically; for each type of arsenic bearing material, different processes have been employed individually to remove the arsenic effectively. In this paper, the flowsheets and typical experimental results have been summarized.

Outotec atmospheric Direct Leaching has so far been implemented for zinc production capacities of around 100,000 t/a. Lately, there has been growing interest for small scale direct leaching plants, producing circa 30,000 t/a of Zn. Such small leaching plants can provide extra front-end capacity in existing roaster-based plants and enable treatment of feed materials not suitable for roasting. In small scale plants the proven OKTOP® 9000 Direct Leaching reactors are not readily applicable, due the large size. For smaller installations a modular approach is proposed providing multiple advantages, such as reducing the construction time and amount of the site work required causing less disturbance to regular plant operation with reduced cost. In this paper, we present advantages that can be achieved by using modular OKTOP®C reactors and discuss also process design when connecting a small scale direct leaching process to an existing zinc plant. Also benefits of direct leaching expansion are presented.

The novel Jarogain process combines treatment of the jarosite residue of zinc manufacturing and processing of arc furnace dust from steelmaking to a holistic recovery technology. The new hydrometallurgical approach is targeted to recover the major constituents (Fe, Zn, Pb) as well as valuable components such as Ag, Au, In and Ga from the jarosite-dust mixture as reusable concentrates. The fractionation process proposed by VTT and Aalto University takes advantage of jarosite being readily fine powder and directly available for wet chemical processing. Jarogain process provides an energy efficient opportunity for jarosite utilization as value added products. The experimental proof-of-concept of key stages of the process will be outlined with a comparison of available pyrometallurgical treatments of jarosite waste. The techno-economical assessment is based on estimated investment and variable production cost using the discounted cash flow (DCF) analysis.

The Betts process for electrorefining of lead has been in operation since 1902 in the Trail Operations Metallurgical complex. The Betts process allows production of high purity lead in a single electrochemical step. Process improvements and plant expansions have taken place over the many decades of operation of this process which has proven to be robust, flexible, and capable of successfully treating a large range of anode bullion compositions. This paper reviews the history of the Betts lead electrorefining process, the innovations and quick industrial adoption of new discoveries that took place at the end of the nineteenth century. The process was first implemented in Trail Operations and integrated very well with metallurgical needs then and now.

Outotec has developed an operator training simulator (OTS) platform suitable for various hydrometallurgical processes. The complete solution is run in the cloud, where virtual client instances can be managed on-demand. The aim is to build a generalizable model that produces coherent results even when operating outside of ideal parameters, allowing the operator to train in unsteady state conditions such as start-up and shutdown. Complex software products are commonly associated with significant development time and cost. Utilizing modular software architecture, only the control system and process model are tailored for the OTS, whereas modules such as user administration and cloud-based client machine spawning can be imported, shortening development time. A generic acidic pressure oxidation process (POX) operator training simulation consisting of feed preparation, autoclave, dual-stage flash evaporation and off-gas scrubbing is described. Process is simulated using Outotec HSC Sim 9 process simulator and controlled by Siemens Simatic PCS7 control system.

This paper describes an experimental approach to evaluate the effect of organic impurities or even additives on metal electrowinning and product quality. In addition to electrowinning tests and electrochemical measurements, the approach includes organic analysis by Fourier Transform Infrared spectroscopy and gas chromatography; video monitoring of the reaction interface; and product characterization by using scanning electron microscopy, crystallographic texture and bending tests. The mechanical behavior of metal cathodes was assessed with a customized bending device that is able to bend the cathodes up to angles similar to that of the stripping machine. In this work, the effect of a potential organic impurity, lubricating oil, on the production of electrolytic zinc is taken as a case study. The findings of the investigation allowed a better understanding on the role of this organic on energy consumption and product quality and a qualitative prediction for the behavior of Zn cathodes during the stripping operation. Simple control and optimization procedures resulted in significant energy savings.

Electrowinning is a significant step in metal extraction processes. Because the nature of electrowinning is to reduce metal from its oxidized state, substantial energy consumption accompanies it. Electrowinning processes of different metals have much in common—the deposition of the metal on the cathode and the counter-reaction on the anode. An advanced model was developed that can be applied to a variety of metal electrowinning processes. A model for specific metals can be readily obtained by modifying parameters such as potential, kinetics, and side reactions in the model. The model incorporates mass transfer, gas-liquid flow, electrochemistry, and deposition, making it a comprehensive electrowinning model. The model is applied to copper, nickel, and zinc and verified with the experimental results. In addition, the parameter settings and results of different metals were compared, showing that this model has great versatility and accuracy, thereby making it an efficient and effective research tool.

Additives are commonly used in copper electrowinning to improve cathode morphology. Polysaccharides such as guar are generally favoured as additives due to their compatibility with solvent extraction. Polyacrylamides are, however, being considered as possible alternatives. Understanding the influence of the structural chemistry of additives on electrowinning performance is critical to utilise them efficiently. This paper investigated polyacrylamide additives which are structurally different; their effects on copper electrodeposition were characterized and compared to that of guar. Electrochemical impedance spectroscopy (EIS) were used to characterize the effects of molecular weight and ionic charge of the polyacrylamides on electrodeposition. The findings were compared against results obtained with an industrially used guar product. Equivalent circuit modelling of EIS data indicated that an increase in polyacrylamide concentration and a decrease in additive molecular weight increased the overall system resistance.

Effect of single addition of a lignin-based biopolymer additive, DP 2782, at various dosages as well as in combination with thiourea on cathode polarization during copper deposition was investigated by performing potentiodynamic and galvanostatic measurements using a potentiostat. The result of electrochemical measurements was compared with the behaviour of cathode deposition with glue and thiourea additives. Surface micro-appearance of the copper deposit after 1 h galvanostatic scan under current density of 330 A/m2 and various additive type and dosage was evaluated by scanning electron microscopy (SEM) examination. It was found that the addition of 2.5 mg/l biopolymer gave sufficiently polarizing effect of copper deposition. SEM examination of the cathode surface after galvanostatic scan revealed that the combination of the biopolymer with thiourea (2.5 and 3.5 mg/l) resulted in a compact deposit which is comparable with that resulted from the test with glue and thiourea.

Manganese in electrolyte has both beneficial and detrimental effects in Zn electrowinning. Mn oxidizes to form MnO₂ on Pb–Ag anodes, cell walls and pipes. MnO₂ reduces anode corrosion but also leads to short circuiting and maintenance issues. MnO₂ is thought to interact with chloride ions and produce oxidized chlorine species. The interactions between Mn and Cl are not well understood. Therefore, two sets of 45+ day bench scale experiments were conducted to investigate the effects of the manganese to chloride ratio on anode corrosion rate and electrolyte chemistry using rolled Pb–Ag anodes. Daily manganese and chloride losses from the electrolyte appeared to be correlated. Increasing the average Mn/Cl− ratio from ~7:1 to ~11:1 reduced the anode corrosion rate. Increasing the ratio above 11 did not reduce the corrosion rate further. Anode scales produced with Mn/Cl− ratios at and above 11:1 contained some γ–MnO₂ while scales formed with ratios less than 11:1 did not.

CobaltCobalt, ironIron and manganeseManganese play various roles in copper electrowinningCopper electrowinning using leadLead–calcium–tin alloyed anodes. CobaltCobalt catalyzes electrochemical water decomposition resulting in lower anode potentialAnode potential and reduced corrosionCorrosion rates. IronIron reduces cathodic current efficiencyEfficiency, but is used to reduce higher oxidationOxidation states of manganeseManganese that oxidize organics in solvent extractionSolvent extraction. ManganeseManganese also produces anode scale and is generally considered a problematic impurity. The effect of the combined interaction of these three metal ions on the anode potentialAnode potential has not been quantified yet. The current work used a three factor, two level, three replicate central composite design of experimentsDesign of experiments to analyze the effects and potential interactions among cobaltCobalt, ironIron and manganeseManganese. The experiments consisted of chronopotentiometric analysis to assess anode potentialAnode potential after 24 h of operation. Higher [Co], lower [Mn] and either high or low [Fe] yielded lower anode potentials. Two regression models were developed to predict anode potentialAnode potential as a function of [Co], [Fe] and [Mn]. A method to estimate electrical energyEnergy consumption for copper electrowinningCopper electrowinning is also presented.

The effect of the anodic polarizationPolarization on the composition and morphologyMorphology of the surface layer formed on chalcopyriteChalcopyrite during ammoniaAmmonia–ammonium chloride leachingChloride leaching was investigated. The anodic polarizationPolarization on the chalcopyriteChalcopyrite electrode was used for oxidationOxidation and dissolution of chalcopyriteChalcopyrite, and the resulting oxidized layers were characterized by XPSXPS, SEMSEM and optical microscopy. The results show that oxide layers exist on the chalcopyriteChalcopyrite surface with or without any anodic polarizationPolarization in the leachingLeaching solution at ambient atmosphere. However, the composition and morphologyMorphology of the layers are strongly depended on the extent of polarizationPolarization. The distributionDistribution of FeOOH and Fe₂O₃ within the oxidized layerOxidized layer was inhomogeneous for the sample at the open circuit potential (OCP). The composition and morphologyMorphology of the oxidized layers which were formed at anodic potentials lower than 0.3 V versus SCE were similar to those of the chalcopyriteChalcopyrite at the OCP. At anodic potentials above 0.4 V, the oxidized layers contained many cracks, and they were fragile and exfoliated. Furthermore, the sulfideSulfide had been oxidized to sulfurSulfur species with higher oxidationOxidation states. The oxidationOxidation of the chalcopyriteChalcopyrite seemed to undergo a cyclically oxidative process that suggested growth and spallation of oxidationOxidation layers on chalcopyriteChalcopyrite in a layer-by-layer sequence.

A process, in which arsenic in the residue is transformed directly into scorodite and copper dissolves into the solution simultaneously, was studied. The process was carried out in acidic ferrous sulfate solution under oxygen pressure. The optimum conditions of the process were determined as follows: the initial H₂SO₄ concentration of 10 g/L; liquid/solid ratio of 10; Fe/As molar ratio in the feedstock of 1; the addition of calcium lignosulphonate was 1% of sludge; oxygen pressure, temperature and reaction time were 1.5 MPa, 150 °C and 6 h, respectively. Under these conditions, arsenic transformed to crystalline scorodite in size of 5–10 μm, and the transformation efficiency reached 97.60%; meanwhile, the copper was leached with a high efficiency of 93.34%. The stability of the leaching residue was evaluated by TCLP testing, and the results indicated the concentration of arsenic in the leaching solution was extremely low as 0.04 mg/L and met the standard of safe stockpile.

HAMR (Hydrogen Assisted Magnesiothermic Reduction) process is a promising alternative route of titanium production, which is convenient due to reduction at relatively lower temperatures below 750 °C and usage of cost-efficient TiO₂ as the starting material. A crucial step involved in this process requires the Mg reduction of TiO₂ subjected to H₂ atmosphere which produces porous TiH₂ along with residual magnesium impurities. Before the final heat treatment and deoxygenation steps for consolidation of the Ti powder, leaching plays a significant role in the removal of Mg impurities. In this report, we present a systematic study on the role of acid concentration (HCl), temperature and the kinetics of MgO dissolution. In addition, we also report the controlling mechanism during kinetics of MgO dissolution in acid. This parametric study will provide a platform to ensure very low Mg content that meets with ASTM standards during production of Ti in the HAMR process.

Electrolytic manganese dioxide, EMD, is the positive electrode material of primary batteries and the raw material of LMC used as the positive mass of lithium ion batteries and is currently produced by anodic deposition on and harvesting from a titanium anode in acidic manganese sulfate solutions prepared by dissolving high purity of manganese sulfate into sulfuric acid solutions. This paper presents an alternative method of EMD production using a novel anode, Mn₂O₃ coated titanium, at lower operating temperature than the current process to explore a possibility of manganese recovery from zinc electrowinning solutions. The Mn₂O₃/Ti anode prepared by thermal decomposition of a precursor solution containing Mn(II) showed the anodic deposition of MnO₂ by constant current electrolysis and the current efficiency was 95% in maximum, while the current efficiency and the crystallographic structure of deposited MnO₂ depended on the current density, the electrolysis time, the bath temperature, and the concentration of Mn(II). The deposited MnO₂ was successfully harvested from the anode and the recovery rate was 98%.

The “BIOMOre” project aims to prove the technical feasibility of indirect in situ bioleaching of sulfide minerals contained in a deep underground deposit, by bringing together the disciplines required to make a success. The underground location in Poland was provided by project partner KGHM inside an operating copper mine. Key components of this project were the design and construction of a pilot plant, and its operation in an underground environment. This project also included a ~250 t (100 m3) fragmented rock reactor hydraulically connected to the pilot plant. The pilot plant consisted of several tanks and pumps, a fluidised bed ferric iron generating bioreactor containing immobilised acidophilic iron oxidation biomass, and all the required instrumentation and utilities. Before the bioleaching phase could start, the rock reactor had to be flushed continuously firstly with water to remove chloride salts that are corrosive and also harmful for the bacteria used in the bioreactor, and secondly, with sulfuric acid solution to react with the carbonates present in the ore matrix. This paper summarizes the design, construction, commissioning, and operation of the pilot plant.

Mining operations generate Acid Mine Drainage (AMD) that poses a significant threat to the natural environment. AMD treatment using Ca(OH)₂ leads to the precipitation of a sludge dominated by a mixture of ferri-oxyhydroxides. This sludge has poor dewatering tendencies and is deposited in landfills with potential for metal remobilization. This study investigated the dewatering behaviour of a precipitate formed during elevated temperature treatment of a primary, pre-settled sludge from the neutralisation of aqueous acidic Fe₂(SO₄)₃ and Ca(OH)₂ solutions in an MSMPR reactor. The resulting treated precipitates were analysed for micro-properties, with results showing that an increase in the secondary reactor temperature from 25 °C up to 50 °C led to an increase in mean particle size, a decrease in the number of particles and improved dewatering behaviour at a ferric concentration of 300 mg/L. This was ascribed to the attainment of a circum-neutral surface charge that favoured agglomeration and a change in micro and nano-structure that allowed for better water passage.

The stoichiometry and kinetics of the hydrothermal reaction of enargiteEnargite in copperCopper sulphate solutions was investigated in the range 140–300 °C, and particle size under 15 and 50 µm. The stoichiometric experiment was performed at 300 °C, using one gram of sample (96% enargiteEnargite, 4% tennantite) and 100 mL of copperCopper sulphate solution (10 gpl) at 1.2 pH. EnargiteEnargite reacted completely after 80 min. A solid product was obtained and characterized by XRDXRD. The main product was chalcociteChalcocite (M) and some traces of djurleite and chalcociteChalcocite (Q). Tennantite did not react under these conditions. The kineticKinetic experiments were conducted at 140 °C, 190 °C, 250 °C and 300 °C. From fitted data and Arrhenius equation the calculated activation energyActivation energy (Ea) was 51 kJ/mol. According to the hydrothermal transformations studied, the reactivity of different phases found in the copperCopper concentrates was bornite > chalcopyriteChalcopyrite > covellite > sphaleriteSphalerite > pyrite > enargiteEnargite > tennantite.

EnargiteEnargite, known as one of the major arsenicArseniccontaining copperCoppermineralsMinerals, with approximately 19% arsenicArsenic, introduces challenges to typical processing options. In most hydrometallurgical processing methods, arsenicArsenic remediation occurs after the copper recoveryCopper recovery in an autoclaveAutoclave or in a stepwise neutralization process. In this study, the in situ precipitationPrecipitationof scoroditeScorodite was investigated during an atmospheric leachingAtmospheric leaching process in the presence of carbon-based catalysts and chlorideChloridemediaMedia. The effective parameters of initial ferric addition, temperatureTemperature, catalyst addition, and oxygen sparging rate were studied and the ferric behaviour was monitored during the scoroditeScoroditeprecipitationPrecipitation. The most influential parameters on efficient scoroditeScoroditeprecipitationPrecipitation are found to be: initial ferric addition, catalyst to concentrate ratio, and temperatureTemperature. A 99% scoroditeScoroditeprecipitationPrecipitation yield was achieved in this process.

The solubility of rare earth (RE) salts in aqueous solutions depends on many factors including the type of cations and anions in solution, their concentrations, temperature and the type of solid precipitated. Experiments were conducted using anhydrous La₂(SO₄)₃ and Ce₂(SO₄)₃·8H₂O as solids and lanthanum(III) perchlorate prepared by dissolving La₂O₃ in HClO₄ solutions as RE-sources. Solutions of H₂SO₄, H₃PO₄ and their mixtures in the presence or absence of Na+, Ca2+, Fe(III) or Al(III) as perchlorates served as test solutions. Saturated solutions and precipitated solids were assayed and characterized using standard techniques to show that the La(III) and Ce(III) ions precipitate as hydrated sulphates, phosphates or double salts with sodium, depending upon the solution composition. The change in solubility of RE-salts with solution composition and temperature is the result of the composite effect of changes in solubility products (pK_SP) of salts, pK_a of acids and other equilibrium constants for ion-association.

Due to increasingly stringent worldwide environmental regulations for gaseous, aqueous and solid waste emissions, conventional smelting technology cannot effectively process arsenic containing materials. Many globally significant copper properties have copper sulfide mineralogy that has a high arsenic content present as enargite with significant contained precious metals. As global copper, silver and gold demand increases while significant world resources decrease, treatment of sulfide orebodies with enargite is becoming increasingly important. Methods to selectively dissolve and fix arsenic, leaving behind clean copper and precious metals-bearing concentrates could effectively treat these ores.

Total pressure oxidationPressure oxidation (TPOX) is widely outreached leachingLeaching practice for base metals from sulfideSulfidemineralsMinerals, wherein high temperatureTemperature (T ~ 200 °C) and oxygen pressure (pO₂ ~ 25 bar) are required. These aggressive conditions intensify the oxygen mass transferMass transfer, and therefore facilitate metal dissolution. However, challenging-cum-negative aspects of such practice are energyEnergy and material intensive requirements and high oxygen demand. Thus, the present study explores the novel emulsified medium for enhancement of oxygen mass transferMass transfer, which assists faster metal dissolution at significantly lower temperatureTemperature and pressure condition. It is possible to achieve quantitative dissolution (>95%) of Cu, Ni and Co from mixed sulfideSulfidemineralsMinerals at T ~ 95 °C and pO₂ ~ 2 bar using an emulsionEmulsion of 2.5% (v/v) n-HexadecaneN-hexadecane in dilute sulfuric acidSulfuric acid. In addition, n-HexadecaneN-hexadecane was found to be inert, stable and immiscible in a pressurized leachingLeaching system, thus can be easily separated and recycled in subsequent leachingLeaching stages. Thus, this study offers an energyEnergy efficient route for low temperatureTemperature-pressure leachingPressure leaching of sulfides.

NMR360 is developing a suite of chlorideChloride-based metals extractionExtraction processes, with the first commercial operation scheduled for commissioning late in 2018. It is critical, therefore, that with the introduction of any new technologyNew technology, that the circuits do not suffer from mechanical failures which will compromise the operation. Although chloride leachingChloride leaching is at atmospheric pressure and relatively low temperatureTemperature, the main challenge is preventing corrosionCorrosion, since the high proton activity makes even a small amount of acid behaves as though it were concentrated. An additional challenge in concentrated chlorideChloride circuits is the potential for solids precipitationPrecipitation. In this context, therefore, correct valve selection is crucial, and NMR360 has partnered with CGIS to ensure that the Severe Service Valves (SSVs) needed will perform over and above the definitions of the Manufacturers Standardization SocietyManufacturers standardization society (MSS) of the Valve and Fittings Industry. This paper outlines what the minimum requirements are for SSVs in chloride leachingChloride leaching applications, drawing on five decades of industry experience from one of Canada’s leading valve experts.

Pressure oxidative treatment of whole ores and/or mineral concentrates is used to leachLeach or liberate metals of value for downstream recoveryRecovery. SilverSilver, when present, is often lost in processing, precipitating as a cyanide-insoluble jarositeJarosite in the residue. Depending on pressure oxidationPressure oxidation conditions, the degree of silverSilver loss to jarositeJarosite can vary dramatically. BatchBatch bench-scale testwork is often performed to define that loss, and then assess the implications in continuousContinuous operations. This paper focusses specifically on the impact of CESLCESLpressure oxidationPressure oxidation conditions on silverSilverrecoveryRecovery, and discusses limitations of batchBatch bench-scale testingTesting as well as means of overcoming these limitations to better predict silverSilverrecoveryRecovery in the scale up from bench-scale to continuousContinuous operations. Since silverSilver is only partially soluble in both sulphate and chlorideChloridemediaMedia, it will gradually leachLeach and deport to a jarositeJarosite as oxidationOxidation progresses. When a silverSilver-insoluble anion, for example iodideIodide, is dosed prior to oxidationOxidation, there is a marked improvement in silverSilverrecoveryRecovery from batchBatch-generated residue; however, that benefit is not consistently seen in continuousContinuous operations. The difference has been attributed to the dynamic solution conditions in the batchBatch test, specifically the first few moments of oxidationOxidation. Using these principles, a predictive correlation has been established between initial leachLeach concentrations of ironIron and acid and ultimate silverSilverrecoveryRecovery with iodideIodide addition.

There are many factors which affect the goldGoldcyanidationCyanidation mechanism—mineral composition, free cyanide and dissolved oxygenDissolved oxygen (DO) concentrations, heavy metal additions, etc. This study combines electrochemistryElectrochemistry and surface analysis methods to examine the effectiveness of the above factors on goldGoldcyanidationCyanidation process. Three goldGoldoreOre samples were used in this study. Sample 1 was a pyrite concentrate, contained mercury and silverSilver. Sample 2 also contained sulfideSulfidemineralsMinerals, including galenaGalena. Sample 3 contained pyrite with sphaleriteSphalerite and galenaGalena. In the case of samples 1 and 2, the presence of heavy metals enhanced goldGoldcyanidationCyanidation kinetics, though the addition of higher DO was not effective on improving the kinetics. Sample 3 showed an opposite behavior: the kinetics was not enhanced by galenaGalena, because of its relatively small amount, however, the use of higher DO made improvement in the goldGoldleachingLeaching kinetics, likely caused by ironIron species generated by pyrite oxidationOxidation.

The addition of lead to a gold leaching reactor can effectively accelerate or retard the gold cyanidation reaction. This study explored the effect of lead on the gold dissolution kinetics using cyclic voltammetry (CV) experiments. It was illustrated that the gold leaching kinetics in the cyanide solution enhanced with the addition of lead salt in the low overpotential region (–0.35 V vs. Ag/AgCl). The similar behavior was observed in the presence of ore containing 0.25% galena. In contrast, the gold oxidation kinetics retarded at –0.35 V (vs. Ag/AgCl) in the presence of silicate and lead-bearing mineral under certain conditions. Likewise, the lead addition was not functional for the high sulfur ore. This was attributed to the oxidation of the sulfides to the elemental sulfur, which subsequently formed a passivating layer on the gold surface. The results were evidently affirmed by the electrochemical tests and X-ray photoelectron spectroscopy (XPS) analysis.

Australia is a major miner of oreOre that requires hydrometallurgical processing. According to the 2016 US Geological Survey MineralsMinerals Commodities Summaries, the country is 1st for aluminiumAluminium (bauxiteBauxite) and lithiumLithium, 2nd for goldGold, zincZinc and cobaltCobalt, 4th for nickelNickel and silverSilver, and 6th for copperCopper mining, not to mention its wealth in coalCoal and ironIron ore. In this paper, examples of recent Australian hydrometallurgical activities are summarised. Then, selected research projects from the University of Queensland hydrometallurgyHydrometallurgy research group are profiled. The projects profiled are related to fundamental aspects of processing bauxiteBauxite with organics and reactive silicaSilica as well as the development of a synergistic hydro- and pyrometallurgical process for copperCopper. The process context and motivation for the research is introduced, key results are highlighted with the associated relevant references.

LeachingLeaching of galvanized steelSteel coatings allows the steelSteel substrate to be used as a zinc-free scrap source to steelSteel and ironIron furnaces. In this study the behaviors of sulfuric acidSulfuric acidleachingLeaching solutions are investigated. The ranked significance of the variables are shown to be acid concentration > temperatureTemperature > zincZinc concentration. Examination of the leachingLeaching mechanism finds the rate-limiting step to be the cathodic hydrogenHydrogenreductionReduction reaction. This rate is not only influenced by acid concentration, but also by the hydrogenHydrogenreductionReduction exchange current density. Dezincing leachingLeaching rates are improved by taking advantage of the higher exchange current density of the ironIron substrate versus the zinc coating. This is accomplished in practice by increasing the exposed interfacial zinc:ironIron surface area through shredding. Also, a leachLeachcontrolControl mechanism is proposed through online monitoring of the zinc-ironIron couple mixed potential.

Leaching of the surface-coated metals from waste acrylonitrile butadiene styrene plastics (WABSP) has been investigated in the ammoniacal solution. The ammoniacal leaching of WABSP (typically containing 4.1 wt% Cu, 1.3 wt% Ni, 0.03 wt% Cr) efficiently dissolved copper and nickel, leaving unleached chromium as fine particles. The results indicate that the anions of different buffer media for metals leaching follow the order: CO₃2− > Cl− > SO₄2−. A declined leaching with high NH₄OH–(NH₄)₂CO₃ ratio (8:1) and a steep rise in extraction with high pulp in solution revealed the influence of anion (CO₃2−) and cation (Cu2+) present in the system. The leaching performed in carbonate solution by maintaining 5.0 M total NH₃ concentration as NH₄OH–(NH₄)₂CO₃ ratio, 4:1; pulp density, 200 g/L; agitation speed, 400 rpm; temperature, 20 °C and time, 120 min yielded the maximum extraction (>99%) of copper and nickel. The study reveals a plausible recovery of the surface-coated metals from the WABSP without altering the properties of polymer material that can be recycled separately.

Greece is the only EU country with extensive nickel laterite deposits. Since the 1960s, the Greek laterites are treated for ferronickel production via a pyrometallurgical route, which involves pre-reduction of the ore in rotary kilns and reduction smelting in electric arc furnaces. Due to the rising cost of energy and the decreasing grade of mined laterites, the pyrometallurgical treatment is economically marginal. For this reason, alternative treatment processes are currently under investigation. Potential applicability of hydrometallurgical treatment, using either H₂SO₄ or HCl, under atmospheric pressure conditions, for Ni and Co extraction from two low grade laterite ores, was examined in the present work. The two samples were selected to represent the different mineralogical composition of the saprolitic and limonitic ore deposits of the Greek laterites. The investigated parameters were temperature (65–90 °C), acid concentration (1–4 N) and solid to liquid ratio (10–30% w/v). The results indicated that HCl was more efficient than H₂SO₄ for the treatment of the saprolitic ore; Ni and Co extractions were very high for both elements, up to 98% and 96% respectively, while H₂SO₄ could leach efficiently Ni, up to 100%, but extracted only 34% of Co. Hydrochloric acid was also more efficient for the treatment of the limonitic ore, with Ni and Co extractions up to 98.3% and 87.6% respectively. With H₂SO₄ the maximum extractions were 71.3% for Ni and 52.1% for Co.

A novel process, which includes hydrochloric acid leaching, iron powder cementation, sulphide precipitation and spray pyrolysis, was proposed to treat iron concentrate recovered from zinc kiln slag for comprehensive utilization. Treated by two-stage hydrochloric acid leaching, the leaching extents of Ag, Pb, Cu, Fe and Zn are 96.78%, 95.14%, 97.72%, 94.51% and 87.74%, respectively. More than 99% Cu and Ag are recovered from the leach liquor when iron powder is 25% higher than the stoichiometric requirement. More than 96% Pb and Zn is removed with three times of theoretical consumption of FeS, and the concentration of impurities of the final solution is less than 500 mg/L. Fe₂O₃ powder, which is spherical with a mean size of 12 μm and purity of 99%, is prepared with final solution at 700 °C. In this process, not only the metal values can be recovered effectively, but also the iron resources of zinc kiln slag can be converted into high purity Fe₂O₃, thus, the comprehensive utilization of iron concentrate recovered from zinc kiln slag can be realized.

In the current study, bio-oxidationBio-oxidation tests were carried out in shaking flasks with a flotationFlotation concentrate containing the sulphides pyrite, arsenopyriteArsenopyrite and gudmidite. The tests were performed with mesophilic microorganisms (At.ferrooxidansAt. Ferrooxidans) at 30 °C and also with the moderate thermophile S. thermosulfidooxidans, at 50 °C. The effects of (i) previous adaptation of the microorganisms to the concentrate, (ii) ferrous ironIron concentration and (iii) pulp density (2%, 4% and 6% (w/v)) on the dissolution of the sulphide were studied through arsenicArsenic extractions. S. thermosulfidooxidans was more sensitive to the pulp density in comparison to At.ferrooxidansAt. Ferrooxidans as a reductionReduction in sulphide oxidationOxidation was observed with the increase in the solid content to 6%. Therefore, the mesophilic strain was selected for further work, which comprised a rolling bottle experiment at 10% solids. After 40 days of bio-oxidationBio-oxidation, the solid material was subjected to cyanidationCyanidation, which revealed 85% goldGoldextractionExtraction as compared to 21% from the original concentrate. The antimonyAntimony sulphide grains in the bio-oxidized product showed similarity to what was observed in the original sample, suggesting such particles were not susceptible to the bio-oxidationBio-oxidation process.

The search for environmentally friendly and cost-effective methods for goldGoldextractionExtraction has been undertaken in order to provide alternatives to the use of cyanide leachingLeaching in the goldGold industry. Among such alternative reagents is the combination of chlorideChloride and hypochlorite ions due to their oxidationOxidation of metallic goldGold and its complexation. Therefore, the current work aims at investigating goldGoldleachingLeaching from an oxidized material by means of a solution comprising calcium hypochlorite and sodium chlorite. The sample used in the current research contained 66.1% Fe₂O₃, 20.4% SiO₂, and 35.7 g/t of AuAu. In addition, XRD and SEM-EDSEds analysis revealed iron oxideIron oxide, quartzQuartz and muscovite as the main crystalline phases in the sample. For comparison purposes, cyanidationCyanidation of the oxidized material resulted in 90% goldGoldextractionExtraction in 24 h. The reference conditions for the leachingLeaching tests with the chlorite-hypochlorite system were: particle size −37 µm, solid/liquid ratio of 10% (w/v), 10 g/L NaCl, 10 g/L Ca(OCl)₂, pH 5–6, 3 h of leachingLeaching. The effects of the: (i) Ca(OCl)₂ concentration, (ii) NaCl concentration, (iii) pH range and (iv) the effect of pulp density in the extractionExtraction of goldGold were assessed. In addition, the stability of the hypochlorite solutions (OCl−) was investigated. The ideal concentrations of Ca(OCl)₂ and NaCl were determined as 25 g/L and 15 g/L, respectively, whereas the optimal pH range was 4–6. Under these conditions, the final goldGoldextractionExtraction reached approximately 84%. By varying the solids content of the pulp (10%, 20% and 30%), it was observed that the lower solids value resulted in greater goldGoldextractionExtraction (84%). The degradation of the hypochlorite solution and the possible catalytic effect of the presence of the solid were evidenced. To sum up, in the experiment, high goldGold extractions were achieved in shorter periods of time (3 h), as compared to the cyanidationCyanidation of the same sample. On the other hand, it was necessary to use significant amounts of the reagent due to hypochlorite instability at the pH conditions recommended for high goldGold extractions.

Atmospheric processing of nickelNickel lateritic ores with low costs has been encouraged. In this work the kineticKinetic of atmospheric acid leachingAcid leaching of a northern-Brazilian oreOre with 1.63% Ni and large amount of fine particles (d₅₀ ≈ 0.075 mm and 40% below 0.038 mm) is presented. Chemical analysis showed a trend of Ni and Fe concentration in finer fraction (−0.075 mm) and Si and Mg in the coarsest one (−0.500 + 0.150 mm) associated to distinct mineral phases. NickelNickel is widespread in the mineral matrix. Distinct behaviors were observed as a function of particle size associated to the distributionDistribution of silicates and ironIron oxides in the oreOre. The kinetic modelingKinetic modeling indicated that leachingLeaching is controlled by porous layer diffusion at 65 °C, but at 95 °C exhibits a mixed controlMixed control by porous layer diffusion in initial minutes (60 min) and by chemical reaction or diffusion through the pore layer in final minutes (60–240 min) depends on metal evaluated.

Mixed phase titaniumTitanium dioxide (TiO_2Tio2)Nanotio2 precipitation nanoparticles synthesized through hydrolysis of TiCl₄ solution at different conditions, namely concentration, pH, and residence time are characterized and evaluated as photocatalysts. The process is operated in a continuousContinuous stirred-tank reactor, CSTR giving blends of anatase, brookite, and rutile nanoparticles that were further evaluated to find the optimum mixture for a photocatalytic sorptionSorption material. The titania nanoparticles are first characterized in terms of photocatalytic activity under UV light illumination using an organic modelModel compound (methyl orange) and after that are tested for removalRemoval of toxic selenate and selenite species from simulated effluent waters.

Ni–Mo ore is a black shale containing amorphous colloidal sulfides which have highly active. The oxygen pressure leaching behavior of nickel from black shale in aqueous media is presented. The effects of agitation speed, temperature, oxygen partial pressure and particle size on the rate of nickel leaching were determined. The results indicate that at low temperature hydrothermal and excess oxygen presence, the amorphous sulfides are easily oxidized to sulfuric acid and sulfate, and leaching nickel. The mathematical analyses of the experimental data for various experimental conditions indicated that the dissolution process was controlled by the chemical reaction during the early stage of dissolution, and was then controlled by liquid-film diffusion. In the initial stage of leaching, the reaction depends on oxygen partial pressure.

The feasibility of the application of electrodialysisElectrodialysis in separationSeparation of light and heavy rare earth elements (REE)Rare earth elements (ree) in synthetic solutions was investigated. The experiments were carried out using single and binary solutions of a light (cerium) and heavy (ytterbium) REE. The effects of electrical voltage, electrical current, and the addition of complexing agentComplexing agent (EDTAEdta) to increase the separationSeparationselectivitySelectivity were investigated. SeparationSeparation of Ce and Yb was achieved in binary solutions with and without the addition of EDTAEdta. Higher degrees of separationSeparation were seen at higher voltages. Ce–Yb separationSeparation was more significant in the presence of EDTAEdta. The separationSeparation factor of Ce–Yb and Ce–Yb-EDTAEdta were 1.44 and 2.60, respectively.

The separationSeparation of cobaltCobalt from other base metals can be achieved using diffusion dialysis in a two-compartment reactor separated by an anion exchange membrane. In this work, a Neosepta AFX membrane was used to study the separationSeparation of various metals in an acid-chlorideChloride solution. The separationSeparation of one metal from another was investigated on the basis of the various chloro-complex stabilities. The metals investigated included cobaltCobalt, nickelNickel, copperCopper(II), ironIron(III), aluminumAluminum, zinc and cadmiumCadmium. The impact of several critical experimentalExperimental conditions, including the initial metal and chlorideChloride concentration in the feed solution and their initial concentration in the receiving solution, on the separationSeparation factor and the metal transfer rate is reported in this work. Effective separationSeparation of different metal pairs was achieved under the experimentalExperimental conditions.

Donnan DialysisDonnan dialysis uses ion exchangeIon exchange membranes to extract and separate cations. The driving force is provided by differences in chemical potential, rather than by electric fields or pressure. A Donnan DialysisDonnan dialysis based process to recover lithiumLithium, nickelNickel, cobaltCobalt, manganeseManganese, and organic acid lixiviant from recycled lithiumLithium ion battery cathodes is under development. In this paper we present a modelModel of Donnan DialysisDonnan dialysis and results of simulations of the aforementioned process. The simulations show that 170 m2 of membranes can process 1000 L of leachate ([Li+] = 0.285 M, [CoCo2+] = [Ni2+] = [Mn2+] = 0.095 M, pH 2) in two days and recover 94.1% of the lithiumLithium (as lithiumLithium carbonate), 99.4% of the transition metals (as mixed sulphates ready for solvent extractionSolvent extraction), and all of the organic acid using 423 mol of H₂SO₄ and 268 mol of KHCO₃.

Electrolytic salt splitting is a technology where acid and/or base is regenerated from a neutral salt using membrane electrolysis. Recent advances in the understanding of brine treatment, membrane stability, and cell design have made electrolytic salt splitting feasible on certain hydrometallurgical solutions. Meanwhile, environmental regulations have made the bulk disposal of salt solutions more difficult. In this paper, sodium sulfate salt splitting is examined from a cost perspective, compared to purchasing the reagents directly. Relative costs are estimated for several regions based on published electricity and reagent prices. The results show that salt splitting is economically favourable in some regions, and can be made more favourable by applying modifications to the traditional three-compartment design.

Anglo Asian Mining have recently installed an industrial-scale UF/RO plant to treat process liquors from the integrated heapHeapleachLeach/agitation leachLeach/resin-in-pulp goldGoldoreOre treatment facilities at their Gedabek goldGold-copperCopper mine in AzerbaijanAzerbaijan. The UF/RO plant is designed to treat 60 m3/h of leachLeach solution to produce discharge quality water. The RO concentrate, which contains elevated concentrations of copperCopper, silverSilver and cyanide, is sent to the company’s SART plant for the recoveryRecovery of the metal values as a precipitated sulphide concentrate and the cyanide, which is recycled to leachingLeaching. The new water treatmentWater treatment plant improves the sustainabilitySustainability of the operations at Gedabek by enabling replacement of fresh water input with RO permeate and safe discharge of permeate to the environmentEnvironment, during periods of excess water balance. The paper includes pilot plantPilot plant data and early results from the full-scale plant.

Water is a critical commodity of our generation and a key compound for the chemical and mining industries. Sustainable industrial development is directly associated with the ability to recover clean water from contaminated sources. Forward OsmosisForward osmosis (FO) is a low-energyEnergy footprint membrane process allowing the recoveryRecovery of clean water from high salinity effluent streams. In FO, water is recovered spontaneously into a concentrated draw solution (CDS). EnergyEnergy is required to separate the recovered water from the resulting dilute draw solution (DDS). In the current work, the fundamentals of the FO process and the most important aspects affecting its performance are discussed. An energyEnergy comparison of FO and conventional water recoveryWater recovery technologies is presented. Finally, the opportunities FO presents in the field of hydrometallurgyHydrometallurgy are analyzed.

High rate compressibleCompressiblemediaMedia filter (CMF) tests produced exceptional total suspended solids (TSSTSS) removalRemoval at hydraulic loading rates ranging from 97.8 to 122.2 m/h. The compressibleCompressiblemediaMedia is manufactured from a robust resin fiber that can withstand low pH and temperatures up to 149 °C. The mediaMedia porosity can be varied by applying compression onto the mediaMedia. At 40% compression, the CMF can remove particles greater than 4 μ. Three synthetic test-samples were generated by Hazen Research Inc., (Golden, Colorado) to simulate the copperCopper Pregnant LeachLeach Solution (PLSPls), RaffinateRaffinate and ElectrolyteElectrolyte solutions used for the testwork conducted at their facility. The preliminary results showed that the CMF was very effective in removing TSSTSS without the use of chemical conditioning from the above test-solutions with efficiencies of 98%, 97%, and 96%, respectively. Given the remarkably high hydraulic loading rates, the industrial equipment footprint would be minimized appreciably over conventional clarificationClarification and alternative filtrationFiltration systems.

Crown ethers are gaining importance in separationSeparation technology specifically for rare earthRare earth elements (REERee, La to Lu plus Y) and precious metalsPrecious metals (Au, Ag, Pt, Pd, Rh and Ir) due to their specific binding ability, metal complex stability and high extractionExtractionefficiencyEfficiency. The selectivitySelectivity of crown ethers in extractionExtraction of these metals depends on different factors, including the cavity diameter and nature of a donor atom of the crown ether, size and charge of the metal ion, diluents and counter ion. Demand for strategic REE and precious metalsPrecious metals are consistently increasing in the world while the separationSeparation of these metals is most challenging tasks. In this paper, the use of crown ethers in separationSeparation of REE and precious metalsPrecious metals, reaction mechanisms and simplified process flowsheets will be elucidated. New reagents with high selectivitySelectivity for the separationSeparation of these metals are further expected to produce high purity metals.

Wheat straw was chemically modified by alkaline treatment followed by succinylationSuccinylation and sodium carbonate treatment for the use of cadmiumCadmium and nickelNickel adsorbent. The adsorptionAdsorptionefficiencyEfficiency was calculated in different conditions. The experimentalExperimental parameters were solution pH, adsorbent dosage, contact time and initial metal concentrations. The biosorbent was analysed by FTIR (Fourier-Transform Infrared SpectroscopySpectroscopy) to investigate the changes of surface functional group. The maximum adsorptionAdsorption percentages of cadmiumCadmium (>99%) and nickelNickel (>98%) were achieved using 5 g/L adsorbent with 50 mg/L initial metal concentrations. The adsorptionAdsorptionkinetic studyKinetic study showed that the reaction was pseudo-second order kinetics and the adsorptionAdsorption isotherm was well fit by the Langmuir adsorptionAdsorptionmodelModel. The dynamic columnColumn study indicates that modified adsorbent has a better adsorptionAdsorption capacity towards cadmiumCadmium than nickelNickel.

GoldGoldextractionExtraction has relied on coconut carbon in adsorptionAdsorption circuits for several decades. IXOS®, invented by 6th Wave Innovations of Salt Lake City, Utah, is a new type of adsorbent that exceeds the selectivitySelectivity of carbon and improves on the mechanical properties of other available resins. IXOS selectivitySelectivity against copperCopper cyanide complexes allows it to be used in circuits that currently struggle with copperCopper contamination. IXOS potential to eliminate or reduce the application of SART technology will expand the opportunities to exploit more complex precious metalsPrecious metals deposits. This paper will describe the technology behind IXOS molecular imprint, its comparison to carbon adsorptionAdsorption in the field, and the effect of efficiencyEfficiency on long-term recoveryRecovery from heapHeapleachLeach METSIM simulationSimulation software.

A wide variety of plants are able to extract nickelNickel (Ni) from soils and accumulate this metal in their foliage. Hydrometallurgical processesHydrometallurgical processes have been developed to recover Ni in the form of metal or salts, starting from the plant A. murale. They include: (1) a combustion step, to obtain ash containing 15–20% Ni; (2) a leachingLeaching step; and (3) purificationPurification. That whole flowsheetFlowsheet has been thoroughly investigated, and the processes scaled up to the pilot scale. Another strategy is presented here, consisting of recoveringRecovering Ni without burning the plant. Ni can be extracted from the dry plant by water leachingLeaching, but the leachate is a multi-element solution from which Ni has to be separated. Selective precipitationSelective precipitation of Ni hydroxide is not possible since Ni is bound to organic ligands. In this work, the plant leachate is processed by adsorptionAdsorption on the chelating resinChelating resinDOWEXTM M4195DOWEXTM M4195. The results showed that Ni was selectively retained whereas the other main cations were not. NickelNickel could be recovered at the elution step. This methodology needs to be further investigated but these initial results are very encouraging and open the possibility of Ni recoveryRecovery by agrominingAgromining.

The use of solvent extractionSolvent extraction (SX) in process metallurgy is particularly attractive as it is applicable to a wide range of solute concentration and pH, and it allows complete separationSeparation of chemically similar metals such as nickelNickel and cobaltCobalt and the rare earths among others. It is therefore applicable to the processing of low grade and complex ores, which is increasing and expanding owing to the diminishing reserves of quality ores, and this has driven the increasing and expanding use of SX.The current SX technology, however, has inherent limitations owing to the use of mechanical agitation as it induces high shear mixing. Excessive shear produces very fine droplets, and while this favours mass transferMass transfer, it also leads to sluggish phase separationSeparation. High shear mixing is also known to favour crud formation. All these factors as well as high power and reagents consumptions contribute to poor process efficiencyEfficiency. Electrostatic solvent extractionSolvent extraction (ESX) is similar to conventional SX except that mechanical agitation is replaced with electrostatic agitation. In direct contrast to mechanical agitation, it allows the production of very small droplets that can be made to maintain intense motion, which favours mass transferMass transfer, without affecting the phase separationSeparation. In addition, as it uses an electrostatic field, the power consumption is minimal. Hence, it promises to be a superior alternative to conventional SX mixing although an application of the technique is yet to be achieved.Our work to develop an application of the technique in process metallurgy has now established that electrostatic field has no effect on either the stability of the reagents or the chemistry of the process. A volumetric flowrate that is comparable to that of a conventional sieve plate pulse columnColumn is achievable. We have also established that electrostatic fields can be made to yield much narrower droplet size distributions than those of mechanically agitated contactors, and they allow better controlControl of droplet motions, which include oscillation and linear motion and hence, mass transferMass transfer. These are significant advancements toward our goal and shall be discussed in this presentation.

The salt lake brines that lithiumLithium is extracted from have high chlorideChloride levels making the brine very corrosive to stainless steelSteelextractionExtractioncolumnColumn internals. This is a significant problem in columnColumn scale-up to industrial production. Two types of corrosionCorrosion-resistant ceramic internals, the hybrid ceramic internal and ceramic plate, were designed and tested under pilot conditions for future industrial application in this field. The hydrodynamic results (Yi et al. Ind Eng Chem Res 56(4):999–1007 (2016), [1]) show that holdup of hybrid ceramic internal is higher than that of ceramic plate by around 50%, while Sauter mean diameter when using the hybrid ceramic internal is smaller than when using the ceramic plate by around 30%. This results in a larger mass transferMass transfer area, hence better mass transferMass transferefficiencyEfficiency for the hybrid ceramic internal. Axial dispersionAxial dispersion and mass transferMass transfer parameters are also examined (Yi et al. Ind Eng Chem Res 56(11):2049–3058 (2017), [2]). The results show that the columnColumn with hybrid ceramic internals has 50% lower axial dispersionAxial dispersion coefficient and 50% higher mass transferMass transfer coefficient, leading to higher mass transferMass transferefficiencyEfficiency. The transfer unit height of the columnColumn using hybrid ceramic internals can be as low as 0.2 m, showing very good efficiencyEfficiency. This is promising for near-future applications. Two-phase computational fluid dynamics (CFD)Computational fluid dynamics (cfd) models have been developed for the two columns with ANSYS FLUENT commercial software. CFDCfd successfully predicts the higher holdup and lower axial dispersionAxial dispersion coefficients for the hybrid sieve plate pulsed columnColumn as measured in the experiments, and the cause for the difference in performance has been explained with information from CFDCfd.

The world’s first large scale modularModularsolvent extractionSolvent extraction plants have been delivered by Outotec. The first of these is now in operation and has provenVSF®X that the VSF®X technology can deliver theVSF® excellent performance of the Outotec VSF® solvent extractionSolvent extraction process. Modular deliveryModular delivery allows site work to be minimized and the manufacturing done in a controlled environmentEnvironment, allowing for serial production manufacturing benefits. Container based delivery was found to be a highly efficient way of utilizing the standardized transportation methods on a global scale. Site work with modularModular units was found to be efficient and highly predictable. In this paper, we present the first successful Outotec VSF®X deliveries and discuss the benefits of the modular deliveryModular delivery and design compared to the standard solvent extractionSolvent extraction installation’s delivery. The process performance of the VSF®X is also discussed with experiences from the first industrial reference presented.

The design options of a gravity separatorGravity separator are still limited and rely on the study of settling behaviorSettling behavior. A methodology will be presented where an experimentally given inlet droplet size distributionDistribution (DSD) is the basis for the calculation of the dispersion layer in a gravity separatorGravity separator. A pilot-scale continuousContinuousgravity separatorGravity separator is presented and CFDCfd (computational fluid dynamic) results are validated. A transmitted light measurement technique for the determination of the DSD is presented up to a holdup of 15% dispersed phase. The resulting DSD was in the range of 20–2000 µm depending on flow rate and phase ratio. Furthermore, correlations of the real DSD with the settling behaviorSettling behavior of the dispersion in a settling cell are discussed. The new approach to the description of gravity separators will be presented and the applied CFDCfd methods showed good results with the system water/paraffin.

CopperCopper(II) and nickelNickel(II) are often recovered from ammoniacal alkaline solutions by solvent extractionSolvent extraction using hydroxyoxime extractants: both copperCopper(II) and nickelNickel(II) are extracted from ammoniacal alkaline solutions and, from the loaded organic phase, nickelNickel(II) is selectively stripped with a dilute acid followed by copperCopper(II) stripping with an acid of higher concentration. Since a small portion of ammoniaAmmonia is coCo-extracted with copperCopper and nickelNickel, the extracted ammoniaAmmonia should be scrubbed using a dilute acid before metal stripping. In the present study, a mechanistic modelModel has been developed in order to support design and controlControl of this process. The equilibrium distributionDistribution ratios of copperCopper(II), nickelNickel(II), and ammoniaAmmonia at 298 K using LIX® 84-ILIX(84-I (active component, 2-hydroxy-5-nonylacetophenone oxime) as the extractant are successfully correlated by considering the relevant equilibriaEquilibria. Based on these results, quantitative prediction of equilibrium distributionDistribution ratios in the process has been made possible, and suitable conditions for the efficient separationSeparation of copperCopper(II) and nickelNickel(II) are discussed.

While McCabe-Thiele plots are useful for designing single-component solvent extractionSolvent extraction systems, not least because of their simplicity, they are less useful for multi-component solvent extractionSolvent extraction. This paper presents a relatively simple method, compared to other approaches, for modelling solvent extractionSolvent extraction as chemical equilibrium reactions between the various aqueous and organic species. The essence of this approach is how values for the equilibrium constants can be extracted from standard laboratory data. Synergistic solvent extractionSolvent extraction of nickelNickel is used to illustrate the method.

The extractionExtraction properties of two synthesized cationic exchangers, i.e. bis(1,3-dibutoxypropan-2-yl) phosphoric acid (BiDiBoPP) and bis(1,3-diisobutoxypropan-2-yl) phosphoric acid (IPA), have been studied for the liquid-liquid extractionExtraction of Co(II), Ni(II)Ni(ii) and Mn(II) contained in 1 M HCl. A comparison of the extractionExtraction properties of these extractants diluted in kerosene withCyanex® Cyanex® 272 shows BiDiBoPP and IPA extract advantageously at lower pH than Cyanex® 272 and a better Co(II)-Mn(II) separationSeparation is achieved using BiDiBoPP or IPA than with Cyanex® 272.

Since the 1970s, Solvent Extraction (SX) in hydrometallurgical processes has been a key enabling technology in the production of high-purity metals. Examples include copper, rare earth oxides, uranium, cobalt and nickel. Notwithstanding incremental improvements in extractant formulations, few breakthroughs can be recounted in this industry outside of the initial amine-, oxime- or phosphine-based reagent chemistries. However, the advent of lithium-ion batteries and their stringent requirements for critical materials (lithium, cobalt and nickel) offer new challenges and opportunities for SX. Solvay recently introduced a new extractant for lithium, CYANEX® 936, and developed unique modeling software capabilities in cobalt/nickel separation using CYANEX® 272, zinc SX using DEHPA® and rare earth separations using CYANEX® 572. This paper discusses trends in SX and provides insight on processing of critical materials essential to energy sources. It also summarizes the technical and economic benefits based on extractant selection and advances in modeling.

The demand for elements such as nickelNickel, cobaltCobalt, titaniumTitanium and goldGold in various applications has increased significantly. Innovation to recover these elements now plays a major role in metallurgical processes as established technologies have challenges in treating the types of ores that are available while meeting the increasingly stricter environmental regulations. Alternative chlorideChloride based processes have been developed that can be used to recover the value elements from the available feed stocks with potentially lower environmental impactEnvironmental impact. ChlorideChloride-based hydrometallurgical processesHydrometallurgical processes have several advantages, including higher leachability of complex ores/tailings and relative stability of chloro-complexes of the metals. Process Research ORTECH Inc. (PRO) has developed mixed-chlorideMixed-chloride process flowsheets, where innovative solvent extractionSolvent extraction process steps are used for the separationSeparation of nickelNickel, cobaltCobalt, titaniumTitanium and goldGold from their respective chlorideChloride solutions. This paper will discuss the potential aqueous chloro-chemistry of these metals and separationSeparation reaction mechanisms involved in the solvent extractionSolvent extraction process.

The high economic value and unique technological properties of the platinumPlatinum-group metals (PGMs), plus their growing scarcity in the Earth’s crust, justify the crucial importance of developing recyclingRecycling practices for PGMs end-of-life materials. Examples of top devices relying on the use of PGMs are automotive and industrial catalysts, and electrical and electronics equipment. This article critically describes the most recent research on the use of solvent extractionSolvent extraction to recover one PGM, palladiumPalladium, from spent catalystsSpent catalysts. Some groups focus on the development of schemes involving commercial extractants, while others prefer to design specific molecules to efficiently and selectively recover palladiumPalladium from these particular complex leachingLeaching solutions. Examples of commercial extractants proposed for the former schemes are Alamine® 308, TBP and LIX® 84I; while on the other hand, sulfurSulfur-containing diamides, thioamides, thiocarbamates, and dithioethers have recently been developed. Ionic liquids have to be mentioned too.

Saganoseki Smelter and Refinery of Pan Pacific CopperCopper Co., Ltd. started treating copper anode slimesCopper anode slimes using a unique hydrometallurgical process in chlorideChloridemediaMedia in 1997. The process comprises the following stages, decopperizing, wet chlorinationWet chlorination, solvent extractionSolvent extraction for goldGold, silverSilverchlorideChloridereductionReduction, and separate reductionReduction stages that treat the goldGoldextractionExtractionraffinateRaffinate with sulfurSulfur dioxide gas. Precious metalsPrecious metals and rare metals in the copper anode slimesCopper anode slimes are dissolved in an aqueous solution of hydrochloric acidHydrochloric acid by oxidative leachingLeaching, which is termed wet chlorinationWet chlorination. GoldGold is efficiently extracted from the chlorination liquorLiquor by dibutyl carbitol in the solvent extractionSolvent extraction stage. GoldGold is reduced by oxalic acid from goldGold-loaded dibutyl carbitol and recovered as goldGold powder. The goldGold powder is cast directly into granules or ingots of more than 99.99% purity without electrorefiningElectrorefining. SeleniumSelenium is recovered as a seleniumSelenium residue by reductionReduction with sulfurSulfur dioxide gas and refined through vacuum distillation. The plant was designed to process 132 tonnes of copper anode slimesCopper anode slimes per month and has a current capacity of 206 tonnes per month due to several enhancements. Compared with the conventional process, the hydrometallurgical process described here provides some advantages, in particular, a higher product quality, shorter goldGold-retention time, and reductionReduction in environmental load.

In this study, Resin-in-Pulp (RIP) technology is used to separate Pb from a chalcopyriteChalcopyrite slurry. Solvent-impregnated resin, Lewatit® VP OC 1026, which contains di(2-ethylhexyl) phosphoric acid (D₂EHPA) in a macroporous polystyrene matrix was used, as the functional group exhibits selectivitySelectivity for Pb over Cu. AdsorptionAdsorption pH, kinetics, as well as resin and CuSO₄ concentrations were investigated. The results show that the kinetics of Pb and Cu loading are fast, reaching the adsorptionAdsorption equilibrium within 30 min. The equilibrium pH of 2 was chosen as optimum for operation in order to achieve a high Pb extractionExtraction rate and extent as well as selectivitySelectivity for Pb over Cu. High Cu(II)Cu(ii) concentration in solution results in Pb(II) requiring a larger amount of resin for the same degree of extractionExtraction. Regeneration and reuse tests show that the loss of adsorptionAdsorption capacity happens in the 1st and 2nd cycles and then the adsorptionAdsorption capacity stabilises for the 3rd cycle.

Pilot TestingTestingIon Exchange ResinIon exchange resin (IEX) can go from very simple beaker testingTesting to complicated columnColumntestingTesting. Space velocities, regenerant quantities, loading capacities, ion leakage, are all terms that get accumulated together to prove or disprove a resin’s (or resins’) ability to load a single ion (or specific set of ions). Not getting all the resin’s operating parameters correct will disqualify (or at least skew) the results. Laboratory tests for capacity, moisture content, bead size, metals fouling, etc.—what does it all mean? At last count, there were over twenty-five separate ion exchange resinIon exchange resin tests (analyses) that were available to end users. Standard testingTesting procedures identify the resin properties but more specific procedures can be used to identify problems with equipment operation. Then, there are the costs to consider; simple cation resin testingTesting (moisture content, total capacity and bead integrity) is in the $200/sample range. However, add to this Chatillon, Russian Ball Mill Test, HIAC particle size, metals and % regeneration test procedures and the lab work can increase to over $1000/sample. In this paper, the author will explain the “must-do” pilot and test procedures and why they are important and the key to understanding how resin performs ion exchangeIon exchange .

AntimonyAntimony and bismuthBismuth are two of the elements that need to be removed from copper electrolyteCopper electrolyteElectrolyte to ensure a trouble free operation as well as to maintain copperCopper cathode purity. One method to controlControl these impurities is the use of aminophosphonic ion exchangeIon exchange resins. AntimonyAntimony is present as both Sb(III) and Sb(V). Sb(V) is very difficult to remove from these resins, requiring excess amounts of highly concentrated hydrochloric acidHydrochloric acid. In industry this affinity of Sb(V) for the resin causes a buildup of Sb(V) and degrading resin performance due to continual reductionReduction of resin capacity. A new method for regeneration of aminophosphonic resins loaded with Sb(V) has been developed, which utilizes catalytic regeneration of the resin. Ion exchangeIon exchange can then be utilized for continual controlControl of Sb and Bi in copper electrolyteCopper electrolyteElectrolyte.

Natural and technogenic sources of rare earth elementsRare earth elements (REEREE) and other rare and scattered metals are remarkable for their chemical diversity. The pregnant solutions going to processing for the valuable metalsValuable metals have very complex compositions. Both targeted elements and competing impurities are present in the solutions in different chemical forms. Thus processing of such materials demands application of different technological tools addressing numerous specific tasks on the way to the final product. Screening work was undertaken to identify the best resins among developmental and commercial products addressing typical cases in the hydrometallurgyHydrometallurgy of scandiumScandium and REEREE. The cases outline typical sources of scandiumScandium and REEREE, such as streams of TiO₂Tio₂ production, extracted phosphoric acid, barren uraniumUranium solutions and others. Specially designed ion exchangeIon exchange resins can be effective tools.

Green chemistryGreen chemistry principles will be discussed, and examples will be given of the use of Molecular Recognition TechnologyMolecular recognition technology (MRTMrt) to selectively separate specialty metals such as cobaltCobalt, nickelNickel, bismuthBismuth, rheniumRhenium, molybdenumMolybdenum, indiumIndium and germaniumGermanium from various primary and secondary feed streams. RecoveryRecovery of these metals has numerous advantages including (i) conservation of valuable resources, (ii) prevention of environmental damage, and (iii) elimination of capital and operating expensesOperating expenses due to re-processing or disposal of metal-bearing streams.

RecoveryRecovery of uraniumUranium in conventional ion exchangeIon exchange circuits, using strong base or weak base resinsWeak base resins containing quaternary or tertiary amine functional groups, is based on an anion exchange mechanism. In saline liquors, chlorideChloride competes with uraniumUranium for the active resin sites and reduces resin loading. This results in significant negative impacts on the IX process in terms of plant throughput and operating costs. In this paper we present the results of a study on the recoveryRecovery of uraniumUranium from an acidic in situ leachLeachliquorLiquor containing approximately 9 g/L chlorideChloride. A range of resins was tested, and a high capacity strong base resin was identified with significantly enhanced loading compared to conventional resins. Other process-relevant criteria such as loading kinetics and elution efficacy are also discussed. The process developed was successfully tested during a recent ion exchangeIon exchangepilot plantPilot plant operated in conjunction with a field-leachLeach trial.

Ore bodies around the world are declining in grade, whilst increasing in complexity. The level of impurities relative to the valuable metal is steadily increasing, posing new challenges to existing operations. Ion exchange is widely used in the hydrometallurgical industry for both primary recovery of metals and the removal of impurities. The superior selectivity of ion exchange resins makes them exceptionally suitable for the removal of target impurities to very low levels, thereby saving operating costs, increasing the value of the final product and significantly improving revenue. The ion exchange process in these applications is very simple, using standard ion exchange equipment and acid regeneration. The process can be fully automated, requiring minimal operator interference and supervision Examples of impurities that are successfully removed via ion exchange include iron, antimony and bismuth from copper electrolyte. In the copper electrolysis process, antimony, bismuth and arsenic tend to form slimes which are dispersed in the electrolyte. These slimes contaminate the cathode and/or decrease the quality of the copper deposition. A special chelating resin was developed to remove antimony and bismuth, while at the same time ensuring minimal chloride leakage to the sulphate matrix. The work is described in more detail in this paper. Ion exchange is also used to remove copper, zinc and nickel from cobalt electrolyte. This paper addresses a few of these examples in more detail.

The separationSeparation of Fe(III) from simulated Ni(II) solutions using different ion exchangeIon exchange resins was studied. The resins tested included cation exchangers with sulfonic and carboxylic groups and chelating resins with iminodiacetic, aminophosphonic, and mixed sulfonic and phosphonic groups. The dosage of resins was varied from 0.1 to 0.5 g/mL to study the impact of resin type and dosage on ironIronseparationSeparation from simulated nickelNickelleachLeach solution containing 25 g/L Ni(II) and 25 g/L Fe(III) at pH 1.5. Also, the effects of different metal ion concentrations, Fe(III):Ni(II) ratios in solution, pH, and adsorptionAdsorption times were investigated. ExperimentalExperimental results demonstrate that all the chelating resins selected favored the adsorptionAdsorption of Fe(III) over Ni(II) with high Fe(III) loading. Soft cation exchange resins also favored the adsorptionAdsorption of Fe(III) over Ni(II), but no significant Fe(III) loading was observed. In contrast, strong cation exchange resins did not show adsorptionAdsorption preferences. The most efficient separationSeparation was observed using resin with aminophosphonic groups at resin dosage of 0.2 g/mL, having a Fe(III) adsorptionAdsorption over 94% and Ni(II) adsorptionAdsorption below 5%.

In this work, we studied the recoveryRecovery of copperCopper from AMD by cementation with ironIron powder. To controlControl the size of copperCopper particles within the nanoscale range, we tested the use of the anionic surfactant sodium dodecyl sulfate (SDS). We tested three concentration levels (0.2, 0.4 and 0.6 M) and temperatures (25, 50 and 75 °C). The activation energyActivation energyEnergy of cementation was also assessed by fitting the experimentalExperimental data with the Arrhenius equation. Under all investigated conditions, the cementation reaction was found to be a diffusion-controlled process. Without surfactant, the activation energyActivation energyEnergy was 19.9 kJ/mol. In the presence of SDS the activation energyActivation energyEnergy increased up to about 35 kJ/mol. With or without SDS, the particle size of the copperCopper product was strongly affected by the cementation temperatureTemperature. Without SDS, the cemented product aggregated into micro-sized clusters of about 15 µm at 25 °C, 2–3 µm at 50 °C and 1 µm at 75 °C. The addition of SDS resulted in a dramatic decrease of copperCopper particle size up down to the nanoscale range. Under the best operating conditions, the particle size of copperCopper was <100 nm.

SeparationSeparation of uraniumUranium and molybdenumMolybdenum in the alkaline leach solutionAlkaline leach solution of a U–Mo ore was studied. A process of acidificationAcidification-solvent extractionSolvent extraction-precipitationPrecipitationuraniumUranium and molybdenumMolybdenum was determined. The influences of solution acidity and phase ratio of acidic scrubbing on separationSeparation of uraniumUranium and molybdenumMolybdenum were examined. The molybdenumMolybdenumextractionExtraction equilibrium isotherm was drawn. The results show that the separationSeparation of molybdenumMolybdenum and uraniumUranium can be achieved by acidifying the alkaline leach solutionAlkaline leach solution, solvent extracting molybdenumMolybdenum using trialkylamineTrialkylamine at equilibrium pH 2.5, and scrubbing the loaded organic phase using sulfuric acidSulfuric acid solution. The strip solution can directly precipitate ammonium molybdate. UraniumUranium can be directly precipitated from the raffinateRaffinate.

Cooling crystallizationCooling crystallization was used to separate ironIron (III) and nickelNickel (II) from acidic sulfate solutionAcidic sulfate solution produced by leachingLeaching of molybdenum-nickel black shaleMolybdenum-nickel black shale. The effect of K₂SO₄ concentration, crystallization temperatureTemperature, solution pH and crystallization time on recoveryRecovery of nickelNickel (II) and precipitationPrecipitation of ironIron (III) was investigated, in order to obtain effective separationSeparation of nickelNickel and ironIron. The optimum parameters determined were as follows: 200 g/L K₂SO₄, 10 °C crystallization temperatureTemperature, solution pH of 0.5 and 24 h crystallization. Under these conditions, 97.6% nickelNickel (II) was recovered as K₂Ni(SO₄)₂·6H₂O crystals and only 2.0% of the total ironIron (III) was precipitated. Recrystallization yielded K₂Ni(SO₄)₂·6H₂O crystals with a purity of 98.4%.

Material criticality reflects the degree to which a raw material is both necessary and subject to supply-chain risks. This study compares the criticality of selected raw materials from the differing perspectives of the manufacturing sectors of China, the European Union, Japan and the United States.

Growing demand for Li-based battery technologies is leading to an unprecedented growth in the lithiumLithium industry. Although innovation in battery technologies has pushed lithiumLithium into the spotlight, lithiumLithium was not always known for its application in batteriesBatteries. The primary use of lithiumLithium—prior to the introduction of commercial lithiumLithium-ion batteriesBatteries in the early 2000s—was in the ceramics, glass, grease, and the medical industry. Before being converted into usable forms, lithiumLithium products must be upgraded from the raw material. Processes for recoveringRecoveringlithiumLithium may involve: thermal treatment, water leachingLeaching, solar evaporationEvaporation, ion exchangeIon exchange, carbonation, and electrodialysisElectrodialysis. Presented, is a historical reviewReview of lithiumLithium applications and the different techniques of converting lithiumLithium-rich mineralsMinerals and brines into usable products with additional discussion on future lithiumLithiumextractionExtraction processes.

Conventionally, lithiumLithium-bearing brines are processed via solar evaporationEvaporation, chemical purificationPurification, and either electrolysis to lithiumLithium hydroxide or precipitationPrecipitation of lithiumLithium carbonate. LithiumLithium-ion battery technology and electric vehicles are forecast to greatly increase the demand for lithiumLithium, but not all lithiumLithium-bearing brines are amenable to the conventional extractionExtraction process and new approaches are being developed. The chemistry associated with conventional lithiumLithiumextractionExtraction is outlined and two new approaches are discussed.

Lithium Australia NL (ASX:LIT) and ANSTO Minerals have been working together since 2015 on the development of halide accelerated leaching for the extraction of lithium from lithium-bearing micas, spodumene and clays. This technology has been termed SiLeach® process. The driving force behind development of the SiLeach® process, initially, was to develop a hydrometallurgical process to extract lithium from micas and spodumene without the need for the energy intensive, high temperature processing conventionally applied to lithium extraction. This driving force remains today and continues to hold promise in realising the value of previously under-utilised lithium resources. A comprehensive understanding of the technology and its applicability to the processing of micas and spodumene currently exists, and the flowsheet has been rigorously piloted. Production of battery grade lithium carbonate has been demonstrated.

Global Geoscience is developing a Rhyolite Ridge project, a shallow boron-lithium resource deposit, located in Nevada about 25 km from Albermarle’s Silver Peak operation. The main minerals of interest are the boron mineral searlesite (40%wt) and lithium containing clay minerals. These minerals are found among principally calcite, feldspar, muscovite, dolomite, and quartz. The equivalent commercial value is about 7–9% boric acid (H₃BO₃) and 0.8–1.0% lithium carbonate (Li₂CO₃) equivalents. Selective agitated leach tests at SGS Lakefield laboratory showed that searlesite can be acid leached between 20 and 75 °C and at a pH lower than 4. On the other hand, lithium can be leached between 20 and 75 °C and at a pH lower than 1. In other words, lithium can be recovered at low temperatures if sufficient free acid is available, which gave the motivation to investigate heap leaching of the mineral. The PLS contains boric acid, magnesium, sodium, lithium, potassium aluminium, and iron sulfates.

Various processes have been developed using a combination of elevated temperatureTemperature and chemical treatment processing to recover Li from silicate mineralsMinerals. To facilitate further process development, a comprehensive understanding of the deportment of Li and associated mineralsMinerals in oreOre bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. This paper describes results from the integrated use of the John de Laeter Centre’s state of the art analytical and mass spectrometry techniques to characterise a selection of Li bearing ore bodies and determine their amenability to potential processing options for the extractionExtraction of Li. The mineralogyMineralogy, mineral associations, and liberationLiberation characteristics of ore-bearing and gangue mineralsMinerals were characterised using a combination of the TIMA and XRPD studies. The Li content and distributionDistribution within mineralsMinerals were defined using LA-ICPMS and field emission scanning electron microscopy techniques (EBSD, ToF-SIMS) and atomic probe microscopy.

Since 1950, the traditional process has been dominating the production of lithiumLithium compounds from spodumeneSpodumene ores to sustain the lithiumLithium market because of its economic viability and the markets need for technical grade (99.5% purity) product. This traditional process includes thermal conversion, acid roasting and lithiumLithiumleachingLeaching. However, this process has not been challenged and very few studies have tried to explain its limitation (95% lithiumLithium yield) or optimize the thermal treatment. Here, α to β spodumeneSpodumene conversion and lithiumLithiumextractionExtraction were performed in a rotary kiln on a 2 mm to 2 cm spodumeneSpodumene concentrate instead of a micrometric one using a 1050 °C, 30 min conversion treatment and 250 °C, 30 min, 30% H₂SO₄ excess leachingLeaching treatment. X-Ray Diffraction analyses were performed on the converted material to determine the conversion rate by Rietveld analysis. It was observed after thermal treatment that the α-spodumeneSpodumene particles fractured and divided while the impurities remained compact. A sifting was performed after thermal treatment and it was determined that 65% of the initial mass became finer than 180 µm. X-Ray diffraction analyses and lithiumLithium content measurement were performed on both fractions and it was determined that the finer fraction had a very high lithiumLithium content of 3.24 wt%. LithiumLithium extractions were performed on both fractions separately. While the coarser fraction’s lithiumLithium yield was only 61% the finer fraction’s lithiumLithium yield went up to 99% without any additional treatment. These observations may open more economical ways for the traditional process by potentially bypassing two third of costly steps such as grinding.

SpodumeneSpodumene [LiAl(Si₂O₆)] is the most common and desirable economic lithiumLithium-bearing mineral due to its high lithiumLithium content. In Canada, there are several spodumeneSpodumene deposits at the development stage that have the potential to help narrow the forecast lithiumLithium supply gap stemming from the widespread acceptance and increasing use of electric vehicles. SpodumeneSpodumene processing can be conducted using Dense MediaMediaSeparationSeparation (DMSDms), flotationFlotation or combination of both. If spodumeneSpodumeneliberationLiberation is sufficient at coarse particle sizes, DMSDms can be used for primary lithiumLithium concentrate production and silicate gangue mineralsMinerals rejection. If liberationLiberation is not sufficient, flotationFlotation is then the main processing route for spodumeneSpodumene concentration. Even in cases where DMSDms is a viable beneficiation option, flotationFlotation may still be required to process the DMSDms middlings and/or the undersize fraction which is outside the particle size range for DMSDms. Considering flotationFlotation as a technique for spodumeneSpodumene beneficiation, there are several alternatives including the use of mechanical flotationFlotation cells, columnColumnflotationFlotation cells, coarse particle flotationFlotation cells, and/or Staged FlotationFlotation Reactors (SFR), either alone or in combination. Ore sorting can be incorporated at the start of the spodumeneSpodumeneflowsheetFlowsheet to remove gangue mineralsMinerals, particularly amphibole and pyroxene in the early stages. The main objective of flowsheetFlowsheet development for hard rock lithiumLithium deposits is to evaluate the ability of these options to produce a spodumeneSpodumene concentrate with a concentrate grade above 6% Li₂O, lithium recoveryLithium recovery of above 80%, and with the minimum operating and capital cost. This paper aims to describe the various processing options available for the beneficiation of spodumeneSpodumene from hard rock deposits and compare the associated operating and capital costsOperating and capital costs for each.

Rare earthRare earth elements (REEs) contained in coalCoal and associated mineral matter exist in several forms including micro-dispersed mineralsMinerals, ion adsorptionAdsorption onto clay surfaces, and chemically bound. Tests found that REEs can be effectively recovered from certain components of three coalCoal sources by leachingLeaching under mild conditions followed by solvent extractionSolvent extraction. A range of pH values were evaluated at solution temperatures of 25 and 75 ℃. When using 1.2 M of sulfuric acidSulfuric acid, nearly 85% recoveryRecovery of the REEs was extracted from the middlings material collected from an operating plant. Acid leachingAcid leaching of a second middling source from another plant resulted in 60% of the total REEs being recovered under the same leachingLeaching conditions. Solvent extractionSolvent extraction treatment of the leachate produced from six different coalCoal sources resulted in products containing up to 50% total REEs from feedstocks starting with around 300 ppm.

Proper handling of the radioactive fraction associated with the production of rare earthRare earth elements (REEs) in the mining industryMining industry is essential for a sustainable environmentEnvironment and human health. Actinides, such as uraniumUranium and thoriumThorium, have similar chemical properties to REEs, and are often co-dissolved in current hydrometallurgical processesHydrometallurgical processes. This causes radioactive contamination of the infrastructure through the extractionExtraction cycle. The present study optimizes, through experimentalExperimental design, a sequential leachingLeaching procedure with Na₂CO₃/NaHCO₃ and HCl for the rapid and selective dissolution of REEs and actinides. OptimizationOptimization focuses on the main operating parameters (time, temperatureTemperature, and concentration); different types of mineralsMinerals, REERee composites, and ores; on achieving maximal leachingLeaching yield; and on minimizing dissolution of the gangue metals (Fe, Si, and Ca). The final sequential procedure was rapid (1 h), effective, and led to the segregation of Th, UU, and REEs with limited dissolution of the gangue metals.

Today’s world relies upon advanced green technologies that are made of critical elements with unique properties. Examples include rare earth elementsRare earth elements (REEs) that are critical in the manufacturing of wind turbines and electric/hybrid vehicle batteriesBatteries, key components of a greener future that face supply uncertainty and near zero recyclingRecycling. To tackle their supply challenges, activities have begun for urban miningUrban mining from waste electrical and electronic equipmentWaste electrical and electronic equipment (WEEEWeee) that contain considerable amount of REEs, but their current level of recyclingRecycling is less than 1%. Current recyclingRecycling practices use either pyrometallurgyPyrometallurgy, which is energyEnergy intensive, or hydrometallurgyHydrometallurgy that utilizes large volumes of acids and solvents and generates large volumes of hazardous waste. In this study, we developed a novel and sustainable process to recycle REEs from WEEEWeee, NiMH batteriesBatteries in particular. The developed process relies on supercritical fluid extractionExtraction (SCFE) utilizing COCo₂ as the solvent, which is abundant, safe, cost effective, and inert. The effect of seven operating parameters, namely temperatureTemperature, pressure, residence time, sample to chelating agent ratio, agitation rate, complex formulation, and methanol addition on REEREEextractionExtractionefficiencyEfficiency was investigated, and optimum operating conditions were determined. This work is the first to utilize a very efficient and safe process that runs at low temperatureTemperature to extract metals from postconsumer products with minimum hazardous waste generation, while offering about 90% leachingLeachingefficiencyEfficiency for REEs. We expect our process to find widespread applicability in urban miningUrban mining of REEs using green chemistryGreen chemistry.

In this study, a combined pyrometallurgical and hydrometallurgical technique has been designed and used to recover rare earthRare earth mixture elements (REERee) and cobaltCobalt from a NdFeB magnetic waste. while addressing the cost of reagent and process facility. This process can be adjusted to different magnetic wastes regardless of their compositions. Prior to the leachingLeaching, the magnet scrap was pretreated by two rounds of roasting (750°C in air) and a mechanical grinding in between, to convert ironIron metal to ferric oxide. Subsequent leachingLeaching was performed using optimized conditions (pH, temperatureTemperature and retention time) where the extractionExtraction ratio of REERee to Fe III is the highest. After removing ironIron content from the leachate (pH ≈ 3), REERee was precipitated selectively and purified further. The produced REERee concentrate reaches 99% purity with 85% recoveryRecovery in a single run. The cobaltCobalt oxide was isolated from the PLSPls as a by-product with 99.8% purity.

MonaziteMonazite, a rare earthRare earth and thoriumThorium phosphate mineral, is one of the major mineralsMinerals processed for extractionExtraction of rare earthsRare earths. Industry practice for treating monaziteMonazite concentrates is to use either a sulfuric acidSulfuric acid bake or caustic conversion route. In the sulfuric acidSulfuric acid bake, monaziteMonazite concentrate is mixed with concentrated sulfuric acidSulfuric acid and roasted. The rare earthRare earth phosphate mineral is converted to rare earthRare earth sulfate which dissolves in a subsequent water leachLeach. As the bake temperatureTemperature increases above 300 °C, thoriumThorium becomes less soluble. Although acid baking is practised in industry, the bake reactions are not well understood. A combination of chemical analysis, XRDXRD and SEMSem-EDSEds was used to identify reaction processes occurring during sulfuric acidSulfuric acid baking of a 93 wt% monaziteMonazite concentrate between 200 °C and 800 °C. The effects of these reactions on the leachability of the rare earthsRare earths, thoriumThorium and phosphate were also examined.

ERAMET, through its subsidiary COMILOG, have rights to a rich niobiumNiobium and rare earthRare earth deposit in Gabon. The Mabounié deposit, is located 50 km from the town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached HatchHatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheetFlowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REEREE feed material for processing in the subsequent leachLeach step. Rare earthsRare earths and niobiumNiobium are selectively leached, and subsequently precipitated. Following precipitationPrecipitation, rare earthsRare earths undergo bulk separationSeparation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheetFlowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

The SCRREEN project gathers more than 50 European initiatives, associations, organisations or independent experts working on Critical Raw MaterialsCritical raw materials (CRM) into a long-lasting network including stakeholders, public authorities, and civil society representatives. SCRREEN contributes to improve the CRM strategy in Europe by (i) mapping primary and secondary resources and substitutes of CRMs, (ii) estimating the expected demand of various CRMs in the future and identifying major trends, (iii) providing policy and technology recommendations for actions improving the production and the potential substitutionSubstitution of CRM, (iv) addressing specific waste electrical and electronic equipmentWaste electrical and electronic equipment (WEEE)WEEE and other End-of-Life (EoL) product issues related to their mapping and treatment standardization, and (vi) identifying the knowledge gathered over previous years and making the data accessible to those beyond the project. As a first step, SCRREEN worked at providing stakeholders with a comprehensive analysis of the current use of the CRM, the mapping of potential primary and secondary resources, and identification of the key technologies used in their production. SubstitutionSubstitution profiles, analysis of European business and policy issues pertinent to CRMs, and an identification of the standards, policies, and regulatory frameworks concerning these CRM was also completed. In a second step, to be conducted between mid-2018 and mid-2019, SCRREEN will provide guidance for improving the CRM market in Europe by identifying opportunities from research, development, and innovation (R&D&I) that could reduce the supply and/or economic risks around the most relevant CRM for Europe.

Rare Earth Elements (REE)Rare earth elements (ree) are fundamental for modern life products and green technologies. Supply constraints and the price peak of 2011 boosted intensive research for alternatives for processing and separationSeparation. Complex monaziteMonazite-type, rare earthRare earth ores usually contain high acid consumptionAcid consumption impurities, such as ironIron and aluminumAluminum, and radioactive thoriumThorium in their composition. These impurities are not removed by conventional concentration processes due to fine, micro-level association between the REERee carrying mineralsMinerals and the gangue mineralsMinerals. This work presents a selective process route for REEReeextractionExtraction from ironIron-rich, monaziteMonazite ores. The process involves sulfationSulfation by addition of concentrated sulfuric acidSulfuric acid and pyrohydrolysis at temperatures of approximately 700–750 °C. ExperimentalExperimental results show REEReeextractionExtraction higher than 70% and low ironIron (below 5%) and thoriumThoriumextractionExtraction (below 10%). A method based on thermogravimetricThermogravimetric analyses was shown to be adequate to predict the behavior of a given oreOre sample in the sulfationSulfation-selective pyrolysisSelective pyrolysis-leachingLeaching process.

In this study, the leachingLeaching kinetics of rare-earth elements were investigated using HCl and HNO₃ solutions. A standard crushed complex oreOre was utilized as raw material. The complex oreOre (particle size of under 54 µm) contains REERee (Ce, La, Nd, Pr, etc.). Different leachingLeaching durations were selected for the kineticKinetic studies. The highest leachingLeachingefficiencyEfficiency was obtained in HCl solution, and the leachingLeaching mechanism was identified to diffusion through a product layer. The rate constants of Ce, La, Nd, and Pr were calculated as 1.08 × 10−2, 0.86 × 10−2, 1.87 × 10−2, and 1.34 × 10−2 h−1, respectively.

Grinding sludgeGrinding sludge from the sintered neodymium-ironIron-boronBoron (NdFeB) magnetsMagnets production process was enriched with critical rare earthRare earth elements (neodymium, dysprosium and praseodymium), which can be up to 30% in the magnetsMagnets. The demand of NdFeB magnetsMagnets are simultaneously growing. Therefore, rare earths recovered from waste residue would reduce the demand of rare earthRare earth elements from primary sources. In this study, the feasibility of recyclingRecycling rare earths through a hydrometallurgical process was investigated. The selective leachingSelective leaching of Nd from grinding sludgeGrinding sludge can successfully raise the rare earths concentration to 70%. The necessity of an oxidationOxidation pretreatment to improve the selectivitySelectivity between Nd and Fe will be described.

When LKAB processes their iron ores in northern Sweden, they generate apatite as a by-product. The apatite has been recovered by flotation and the concentrate contains about 0.4 wt% rare earth elements (REE). Both phosphate rock and REE are listed as critical raw materials for the European union. In the present study, the recovery of REE within the nitrophosphate process of fertilizer production has been studied. In the first stage, the REE are precipitated and isolated as a phosphate concentrate. For further purification and individual separation of REE by solvent extraction, removal of phosphorous from the concentrate to enhance the dissolution of REE in mild acidic solutions is essential. In this study, thermal treatment of the concentrate with sodium hydroxide at elevated temperatures followed by water leaching has been studied in order to separate the phosphorous and thereby facilitate dissolution of the REE. The results show that 95% of total phosphorous initially present in the REE phosphate concentrate is removed after thermal treatment with NaOH 1:1 mass ratio, at 400 °C.

Mintek has developed a non-destructive Resin-in-LeachLeach method for the recoveryRecovery of Rare Earth Elements (REE)Rare earth elements (ree) from phosphogypsumPhosphogypsum (PG) waste dumps. However, PG from different sources was found to be highly variable in terms of REE recoveryRecovery and physical properties. Development of a pre-treatment process was initiated to improve the robustness of the current REE recoveryRecovery process in order to render it effective for any type of PG. Extensive research into the mineralogyMineralogy of REE associations with PG revealed that the majority of REE are trapped inside phosphogypsumPhosphogypsum clusters which inhibits their recoveryRecovery. Hydrothermal treatmentHydrothermal treatment of PG-containing slurry was found to result in re-crystallisation of gypsumGypsum with the release of REE phases encapsulated in it. This process was tested on various PG samples and subsequent REE recoveries improved from 5 to 80%. This approach carries a large potential for unlocking value associated with gypsumGypsum dumps worldwide.

The recovery of rare earth elements (REEs) through heap leach/in situ techniques from so-called ion adsorption clays (IACs) is attractive due to their inherent simplicity. However, the underlying mechanisms of these processes are poorly understood. In this study, the deportment of REEs in a typical IAC material has been investigated and was found to concentrate in the phyllo-layers of the clays, especially hallyosite, and was readily desorbed by various ion-exchange reagents indicating various potential routes to liberate them. Here we are reporting the use of seawater (0.5 M NaCl), spiked with various amounts of (NH₄)₂SO₄, and found better extraction using a reagent mixture than NaCl on its own. Further, the leaching of REEs from a bed of clay material was investigated over time to understand the rate of transport through the stagnant material. Results indicate that REE release is likely to be controlled by diffusion through the clay material, while desorption in agitated systems is rapid. A degree of fractionation between different REEs can be observed during diffusion. Nonetheless, the successful operation of in situ leach operations for this type of material would depend primarily on how easily solution cocktails can be made to flow through the bed material.

The thermodynamicsThermodynamics of tungstenTungstenoreOre decomposition in mineral acidMineral acid and alkaline solutions were studied. The published thermodynamic data of tungstenTungstenmineralsMinerals were collected and assessed. The Gibbs energies of CaWO₄ (−1538.43 kJ/mol), FeWO₄ (−1053.91 kJ/mol), MnWO₄ (−1206.08 kJ/mol), H₂WO₄ (−1003.92 kJ/mol), and Na₂WO₄ (−1455.58 kJ/mol, aq) at 25 °C were adopted in the calculation using HSC software. The results show that CaWO₄ is decomposed more readily in Na₂COCo₃ solution than in NaOH, while FeWO₄ and MnWO₄ are more reactive in NaOH solutions. From a thermodynamic point of view, tungstenTungstenoreOre decomposes easily in acid solutions despite most $$ \Delta G_{T}^{o} $$ΔGTo increasing slightly with temperatureTemperature. Oxidizing Fe2+ to Fe3+ in acidic solutions facilitates decomposition of FeWO₄, and the reaction of CaWO₄ in H₂SO₄ solution occurs more easily than in other mineral acids, due to the formation of sparsely soluble CaSO₄. The results fit well with the experimentalExperimental data and industrial experience previously reported in the literature.

Currently, spent V₂O₅–WO₃/TiO₂TiO₂ catalysts contribute significant amounts of solid waste following increasing levels of global demand. V₂O₅–WO₃/TiO₂ catalysts usually consist of TiO₂ anatase as a supporting oxide, vanadiumVanadium as a catalytic agent, and other promoters such as tungstenTungsten, siliconSilicon, and calcium. Although vanadiumVanadium is the main catalytic agent, a relatively high content of tungstenTungsten (WO₃, 7–10 wt%) typically exists compared to vanadiumVanadium (0.5–1.5 wt%). Considering the irreplaceable properties and industrial importance of tungstenTungsten, a feasible method for the recyclingRecycling of spent V₂O₅–WO₃/TiO₂ catalyst should be established to utilize it as a secondary sourceSecondary source. This paper presents a process to recover tungstenTungsten from spent V₂O₅–WO₃/TiO₂ catalyst. The processes proposed here involving roasting, decomposition using HCl, ammoniaAmmonialeachingLeaching, and crystallization. Within the process, ammonium paratungstate (71 wt% as WO₃) is obtained as a final product. The total yield rate of tungsten from feedstock was found to be 96.3%.

TungstenTungsten carbide scrap (WC–Co) is material generated from the tungstenTungsten carbide manufacturing process and worn out or used carbide parts from industry. TungstenTungsten (W) ores contain about 3 wt% WO₃ and their W concentrates about 10–75 wt% WO₃. TungstenTungsten carbide scrap typically contains 40–95 wt% W. The high intrinsic value of W and the fact that the least valuable scrap contains more W than the average tungstenTungsten ore makes tungstenTungsten carbide scrap a worthy material for re-use. This study has investigated the selective dissolution of the cobaltCobalt (Co) binder phase, and recoveryRecovery of tungstenTungsten monocarbide (WC) and Co using an acid leachAcid leach process. The Co component was selectively leached leaving the WC solid particles intact. Further investigation using a complexing agentComplexing agent-aided acid leachAcid leach process that takes advantage of organic chelating agents that form a soluble tungstenTungsten complex in place of the passive insoluble tungstenTungsten oxide is envisaged. The optimal dissolution of the Co binder phase using an inorganic acid in conjunction with an organic complexing agentComplexing agent is a novel approach with the potential of reduced leachingLeaching times and possibility of regenerating the unreacted organic acid.

Despite the ubiquity of applications for germanium, there is a lack of practically useful solubility data in acidic solutions. Previous studies were done at ambient temperature and only for commonly used acids (H₂SO₄, HCl). Hence, an investigation of the solubility of GeO₂ in different acids was undertaken. Several inorganic and organic acids were studied in the concentration range of 1–11 mol/L and at 23, 40, and 60 °C. In the case of H₂SO₄ and HCl previous data was confirmed. Lower acidity resulted in a higher solubility for Ge at all tested temperatures. Tests done at 40 and 60 °C and low to moderate acidity levels, gave slightly increased solubility values at higher temperatures compared to 23 °C. This wasn’t the case at higher acidity levels, i.e., the solubility curves at different temperatures converge at high acidity. Lastly, a relationship of water activity and GeO₂ solubility in different acid media was established.

GermaniumGermanium is widely used in many fields, and the production of germaniumGermanium is very important. The effects of initial sulfuric acidSulfuric acid concentration, liquid to solid ratio and other parameters on the leachingLeaching rate of germaniumGermanium and zincZinc from germaniumGermanium-bearing zinc oxideZinc oxide has been studied. The occurrence and form of germaniumGermanium and other elements in the leachLeach feed and the leachLeach residue were studied by EPMA, XRD and chemical analyses. The experiments showed that the leachingLeaching rate of germaniumGermanium and zinc was 91% and 88%, respectively under optimal conditions. Wurtzite was the main limiting factor for the leachingLeaching rate of zinc while the leachingLeaching rate of germaniumGermanium was limited by insoluble germaniumGermanium compounds. Furthermore, it was found that some germaniumGermanium was bound up in galenaGalena in the leachLeach residue. These results may be helpful for further improving the leachingLeaching rate of germaniumGermanium in germaniumGermanium-bearing zinc oxideZinc oxide.

For use in many existing and emerging applications, the purificationPurification of natural graphiteNatural graphite is required to achieve +99.9% carbon content with minimum metallic impuritiesMetallic impurities. Currently, the hydrofluoric acidHydrofluoric acid process is used, which carries certain environmental and workplace health and safety impacts. While thermal purificationThermal purification of graphite at temperatures over 2500 °C is a known alternative, such high-temperatureTemperature furnaces are expensive to build and operate. Using chlorine at lower temperatures to purify graphite is also known and patented, but is currently limited to treating solid synthetic graphite shapes in small-scale batchBatch furnaces. Chlorine treatmentChlorine treatment of natural flake graphiteFlake graphite resources can be used commercially, if certain drawbacks are addressed through process improvements that can be helped with the use of fluidized bed reactorFluidized bed reactor technology.

Up to one half of neodymium and praseodymium production, key ingredients in permanent magnets, is produced illegally. About 60% of cobalt production, critical in lithium-ion batteries and other applications, comes from central African states, and much of it is produced illegally. Tantalum, important in modern electronics, is also primarily sourced from central Africa and, again, much of it illegally. Illegal mineral production, as exemplified here, is often used to fund armed conflict. Furthermore, it is typically conducted with scant regard for human rights and environmental protection. It also leads to depressed prices which in turn limits the possibility of legitimate producers entering the market. Systems of traceability and provenance, along with cooperative supply chain participants can limit the production of illegitimate material and thereby improve conditions in the countries of origin and reduce downward pressure on prices.

NioCorp is developing the niobiumNiobium/scandiumScandium/titaniumTitanium Elk Creek carbonatite deposit. The probable reserve announced by the company in 2017 indicated significant niobiumNiobium (0.79% Nb₂O₅), titaniumTitanium (2.81% TiO₂), and scandiumScandium (71 g/t), and is composed predominantly of calcite, dolomite, and ankerite. NiobiumNiobium is mostly (80%) contained in pyrochlorePyrochlore with the balance in various Fe-Nb-Ti oxides, which also host most of the titaniumTitanium. ScandiumScandium is primarily deported in dolomite, with lesser quantities in pyrochlorePyrochlore and biotite. The process flowsheetFlowsheet recovers separate niobiumNiobium, titaniumTitanium, and scandiumScandium products. ScandiumScandium is extracted from whole ore hydrochloric acidHydrochloric acidleachLeach solutions using solvent extractionSolvent extraction and is further refined through a re-leachLeach and precipitationPrecipitation process. ScandiumScandiumleachLeach residues are treated in a sulphuric acid sulphation process to recover separate niobiumNiobium and titaniumTitanium precipitates as well as to solubilize the remaining scandiumScandium. Both hydrochloric acidHydrochloric acid and sulphuric acid reagents are recycled within the flowsheetFlowsheet. This paper will discuss key bench and pilot test results of the niobiumNiobiumextractionExtraction and recoveryRecovery circuits and will present a conceptual flowsheetFlowsheet developed by the project team for NioCorp at SGS MineralsMinerals.

Since their commercialization in the early 1990s, lithiumLithium-ion batteriesBatteries (LIBs) have become ubiquitous for powering a myriad of portable electronics. Their usage now extends to the automotive industry and stationary energyEnergy storage market. With an average life of 6.2 years and the strong demand, the volume of spent LIBs has increased exponentially, making recyclingRecycling mandatory. Currently, recyclingRecycling/recoveryRecovery of spent LIBs is limited in comparison to all other types of batteriesBatteries. The current processes focus mainly on the recoveryRecovery of the most valuable metalsValuable metals such as cobaltCobalt and nickelNickel, leaving lithiumLithium and phosphate in a low value end-product. It is necessary that new advanced recyclingRecycling technologies are developed for the recoveryRecovery of spent LIBs both from an economic and environmental perspective. In this paper, the current R&D status of LIBs recyclingRecycling is reviewed with the emphasis placed on hydrometallurgical processing opportunities for Li-ion and Li-solid stateSolid statebatteriesBatteries.

Lithium metal silicates (Li₂MSiO₄, M = Fe or Mn) composed of abundant and non-toxic elements are important cathode materials for Li-ion batteries (LIB). In contrast to solid-state or sol-gel methods, hydrothermal synthesis conducted in pressure reactors is a favorable processing route as it provides the potential for scalable production and is environmentally benign. However, the key is to control the precipitation reaction to obtain powders with desired properties to meet battery specifications. Through a systematic study, we have found that Li₂MSiO₄ with tunable size from 300 nm to 1.5 μm can be produced by adjusting precursor concentrations, temperature, and reaction time. Under optimum conditions, high purity Li₂MSiO₄ with minimum defects were successfully produced and examined as an LIB cathode. The use of complexing agents promoted the formation of unique hollow particles via the self-assembling of elongated crystals. A four-step formation mechanism is proposed based on extensive characterizations with XRD, HR-TEM, SEM, and Mössbauer spectroscopy.

Processes are needed to rapidly and cost-effectively produce highly pure lithiumLithium salts for the rechargeable battery sector. LithiumLithiumpurificationPurification is a chemical engineering challenge, due to the low concentration of lithiumLithium compared to sodium, potassium, magnesium, calcium, and transition metal ions commonly occurring in lithiumLithium brine resources. We describe a Solid Phase Extraction (SPE)Solid phase extraction (spe) process that rejects sodium and potassium, while binding lithiumLithium and other higher valent ions. LithiumLithium is then harvested by selective displacement from the SPE columnColumn. The rapid equilibration kinetics of SPE composites enables these ion separations to occur in a small SPE columnColumn and in one columnColumn stage. The chemical parameters of the process are described.

IsotopesIsotopes are critical to a variety of applications including physical science analyses, biology, medicine, pharmaceuticals, and national security. In most cases isotopesIsotopes must be relatively pure or highly enriched before they become useful. Current isotope separationSeparation technologies are relatively inefficient, capital and labor intensive, and often produced by a limited number of suppliers. In the category of isotopesIsotopes, lithiumLithium is among other important candidates. LithiumLithium is found naturally in two isotopesIsotopes, 6Li which accounts for 7.5% of all lithiumLithium, and 7Li which makes up the balance of 92.5%. Each of these isotopesIsotopes is important to the nuclear industry. 7Li is often used in the form of lithiumLithium hydroxide which is used to controlControl pH in pressurized water reactors. The current supply of 7Li is based mostly outside of the United States, and its long-term supply is uncertain. Apart from supply issues, the use of mercury for 7Li separationSeparation is also a concern in commercial processing using the most common and efficient approach [1–3]. Hence, a reliable, environmentally friendly, and efficient technique is needed to produce 7Li. In this line of investigations, the authors used a two-compartment system and significant separationSeparation was achieved. In this piece of research, some preliminary results are presented including cell design and actual isotope ratio after enrichment. Applying an electro-potential across two electrodes can be used to drive electromigration of Li isotopesIsotopes. The electromigration is in addition to normal diffusion. Note that 6Li diffuses faster and hence there will be a lowering of the 6Li concentration near the positively charged electrode and an enhancement in 6Li near the negative electrode during the separationSeparation process. Similarly, 7Li will be more prevalent near the positive electrode and less prevalent near the negative electrode during the initial separationSeparation stage [1].

Montana Tech has been engaged in fundamental research on the processing of critical materials for more than a decade. Efforts include examining novel reagents for the flotation of Rare Earth Minerals (REMs). For this paper, research results on a collector, salicyl hydroxamic acid (SHA), are presented. Various REMs were examined and include the rare earth oxides (REOs), carbonates (RECs), and phosphates (REPs) of a suite of Rare Earth Elements (REEs). Differences are attributed to solution and surface chemistry, coordination number, and ionic diameter. SHA adsorption follows an ion-exchange process that leads to chemisorbed and surface-precipitated states, depending mostly on pH. Many effects are directly attributed to lanthanide contraction. Results should also be applicable to other REM/collector systems and further suggest that REM flotation should consider dual collectors.

Rapid technological development has caused an increase in the demand for rare earths. Ancylite, a strontium rare earthRare earth carbonate, is a potentially significant source of rare earths. In this research paper, essential aspects of the magnetic separationMagnetic separation and flotationFlotation processes for Bear Lodge oreBear lodge ore are presented. A flowsheetFlowsheet is proposed based on an optimizationOptimization of the variables and flotation simulationFlotation simulation. The economic feasibility of the proposed processing operation is analyzed.

Many postconsumer electrical and electronic equipment wastes contain a considerable amount of rare earth elements (REEs); however, the current level of REE recycling from them is limited (<1%). Neodymium–iron–boron (NdFeB) magnets, used at both small- and large-scale, from computer hard disk drives and small tools to wind turbines and cars, are a good example of such waste materials that contain high content of neodymium (Nd) and dysprosium (Dy). These elements are considered critical metals because they are the main building block of emerging green technologies that will allow for GHG emission reductions. Because demand for these green products is increasing around the world, the demand for REEs is increasing quickly, putting their supply at risk in the near future. Thus, it is critical to develop efficient, robust, and cost-effective processes to recycle these elements from this class of electronic waste materials. Here, we performed a thorough characterization of a N52–NdFeB magnet to identify its composition, crystal structure, and morphology. Furthermore, we developed an efficient hydrometallurgical process to extract Nd and Dy with high efficiency (more than 95%).

NdFeB permanent magnetsMagnets are the best available magnetsMagnets used in many technology applications. However, at their end-of-life (EoL) most of magnetsMagnets and the contained REEs are lost during the recyclingRecycling of the bulk metals. The REEs are classified as the most critical raw materialsCritical raw materials in the European Union, and recyclingRecycling of REEs from EoL products will reduce their criticality and contribute to the sustainabilitySustainability of REE. Various technological routes have been reported, but most of the methods are effective for highly concentrated magnetsMagnets or magnet scrap, which is greatly dependent on expensive pre-dismantling processes. This paper presents various innovative metallurgical solutions to the effective REE recoveryRecovery from current industrial practice for WEEEWEEErecyclingRecycling, including the ferrous scrap from WEEE shredder products and shredder residues from computer hard disk drives. Both hydrometallurgical and combined hydro- and pyrometallurgical REE recoveryRecovery routes are developed after demagnetization and physical upgrading.

After water leachingLeaching of an acid baked REE concentrate, impurities such as Fe, Al, Th, and Cu are removed by neutralization with different reagents such as NaOH, Mg(OH)₂, MgCO₃, CaOCaO, and CaCO₃. Among these chemicals, limeLime (CaOCaO) and limestoneLimestone (CaCO₃) are the preferred reagents due to their low costs. However, because of calcium sulfate dihydrate (gypsumGypsum) precipitationPrecipitation, they are not so common in industry. One of the disadvantages of gypsumGypsumprecipitationPrecipitation is the adsorptionAdsorption of REE to the precipitates, losing a fraction of REE to gypsumGypsum which is hard to recover. In this paper, batchBatch and continuousContinuous conditions in the impurity removalImpurity removal process using limestoneLimestone are investigated and the differences between these two processes are examined. Based on the experiments, REE uptake by gypsumGypsum significantly increases in continuousContinuous processes, and different gypsumGypsum morphologies are observed.

Rare earth elements (REE)Rare earth elements (ree) are regarded today as highly critical raw materialsCritical raw materials but currently lack suitable recyclingRecycling processes. A combined hydro- and pyrometallurgical process aimed at REE recoveryRecovery from used NdFeB permanent magnetsMagnets was recently developed by the CEA. The process integrates the physico-chemical treatment of magnetsMagnets, followed by a solvent extractionSolvent extraction step for the recoveryRecovery and intra-REE separationRee separation using a selective extractant. A subsequent pyrometallurgical treatment via molten chlorideChloride salt electrolysis allowed the isolation of pure Dy metal. Technical-economic assessment and life-cycle analysis were also conducted. Following this first successful demonstration, a new project aimed at the recoveryRecovery of REE from end-of-life nickelNickel-metal-hydride batteriesBatteries is currently being developed in association with industrial and academic partners. The project aims at evaluating from an experimentalExperimental and economic perspective different processes converging at the production of value-added products such as cermet materials for catalytic applications, purified REO concentrates, or metallic alloys.

AgrominingAgromining is a phytotechnology aiming at producing commercial metal compounds from low-grade ores thanks to hyperaccumulating plants. The fern Dichranopteris dichotoma is a rare earthRare earth element (REE) hyperaccumulatorHyperaccumulator, which naturally grows on former mine tailingsMine tailings in China. It accumulates up to 0.35% of REEs in its aerial parts. Different hydrometallurgical processesHydrometallurgical processes are currently developed to recover these elements directly from the biomass or from ashes after combustion. The process presented here consists of a direct extractionExtraction by EDTAEdta solution, followed by precipitationPrecipitation with acid oxalic. Optimal precipitationPrecipitation pH and influence of organic matter are determined by modelling and by experimentalExperimental studies. The final solid contains 4.3% of REEsREE, with calcium as the main cationic impurity (0.45% of the precipitate). The recoveryRecovery yield is similar for major REEs and is around 70%. After optimizationOptimization, upscaling of the process will allow the agrominingAgromining development to recover REEs from secondary resources with more environmentally friendly techniques.

The growing use and acceptance of electric vehicles (EV), as evidenced by the record sales of over 750 thousand vehicles in 2016 and a current global EV stock of 2 million vehicles, is putting pressure on sourcing raw materials such as cobaltCobalt, and to a lesser extent, nickelNickel. Global supply is poorly diversified, with 50–60% of global cobaltCobalt production sourced solely from the Democratic Republic of Congo (DRC). One potential source for cobaltCobalt and nickelNickel are low-grade nickeliferous pyrrhotiteNickeliferous pyrrhotite tailings, of which 50–100 million tonnes are present in the Sudbury area alone. This paper presents the extractionExtraction of cobaltCobalt and nickelNickel from this material using a combination of flotationFlotation and bioleachingBioleaching technologies. The findings of a high-level techno-economic analysisTechno-economic analysis of the proposed processing flowsheetFlowsheet are presented.

For sources with an ironIron-to-vanadiumVanadium ratio of far above 1, it is proposed to leachLeach in acid and to oxidize under autoclaveAutoclave conditions. During this oxidationOxidation process, it is experimentally shown that divalent ironIron contained in this solution will be oxidized to trivalent ironIron, whereas free acid contained will be consumed by this reaction. In case no acid is present or already fully consumed, a solid consisting of ferric compounds and an ironIron-vanadiumVanadium-coCo-precipitate will form that can be filtered from the solution. If choosing the right reaction conditions, this filter cake has an ironIron-to-vanadiumVanadium ratio of close to 1, whereas the liquid remainder is almost vanadiumVanadium free. This precipitate, identified as FeVO₄ · 1.1 H₂O, can be processed by conventional technologies such as caustic leachingLeaching, or probably salt roasting or reductionReduction with aluminumAluminum, yielding common marketable products.

LithiumLithium is a key component for future electric vehicle batteriesBatteries and energyEnergy storage. The future availability of lithiumLithium to meet the growing demands remains in question. Around 60% of lithiumLithium resources exist in the form of continental brines. Traditional methods to recover lithiumLithium from brines use solar concentration with precipitationPrecipitation and have found limitations in lithiumLithiumextractionExtraction due to interference of Mg in high Mg/Li brines. Thus, there is a need for highly selective adsorbents. Recently, spinel structured delithiated lithiumLithiummanganeseManganese oxides have demonstrated promising results. However, due to the small particle sizes, it is economically difficult to recover the adsorbents and thereby limits industrial applications. In our work, LiMn₂O₄ ion sieve was synthesized and immobilized on diatomaceous earthDiatomaceous earth. Fundamental adsorptionAdsorption studies were carried out in lithiumLithium buffer solutions to understand the nature of adsorptionAdsorption and kinetics. The adsorbents were also tested for recycle stability, as well as recoveryRecovery of lithiumLithium from Great Salt Lake water samples.

ScandiumScandium (Sc) has unique properties and is one of the more valuable elements in the periodic table. ScandiumScandium can be used in solid oxide fuel cells and to produce high strength aluminiumAluminium alloys of value, for example, in the aerospace industry. ScandiumScandium is often grouped together with the rare earth elements (REE)Rare Earth Elements (REE). Amongst others, scandiumScandium can be found in bauxiteBauxite residues, so called red mudRed mud. It is possible to extract and enrich scandiumScandium from red mudRed mud by leachingLeaching and solvent extractionSolvent extraction. ScandiumScandium can then be recovered from the pregnant strip liquorStrip liquor by crystallization. The strip liquorStrip liquor will however still contain certain impurity elements. In the present work, a method for obtaining a pure scandiumScandium solid phase by direct crystallization from the strip liquorStrip liquor is evaluated. It was found that Fe and Ti co-precipitate with Sc under the conditions employed.

Bauxite residueBauxite residue is an environmentally unfriendly byproduct of aluminaAlumina manufacturing, produced worldwide in large quantities. This material contains 50–100 ppm of scandiumScandium, a critical material for the production of stronger, weldable, corrosionCorrosion resistant, and heat tolerant aluminumAluminum products. Aircraft manufacturers are particularly interested in Al–Sc alloys because of its ability to form weldable alloys that could potentially reduce aircraft weight by 15–20%. Because of its abundance and low cost, bauxite residueBauxite residue has the potential to be used as an efficient feedstock for valorization processes to recover its scandiumScandium content, while in turn degrading this problematic waste. In this project, we developed an efficient process to recover scandiumScandium and rare earthRare earth elements from a Canadian bauxite residueBauxite residue with high extractionExtraction yields, using industrially scalable and economical techniques. The process employs a modified version of sulfuric acidSulfuric acidleachingLeaching and subsequent impurity removalImpurity removal by selective precipitationSelective precipitation. This article outlines the current progress and design rationale in the development and optimizationOptimization of this innovative and sustainable recoveryRecovery process.

The extractionExtraction of scandiumScandium from its oxide with a task specific ionic liquidIonic liquid [Hbet][Tf₂N] offers potential advantages of lower energyEnergy consumption, recyclingRecycling of the extractant and reduced environmental impactEnvironmental impact compared to conventional methods. In this paper, the influence of reaction temperatureTemperature, solid to liquid ratio and water to the ionic liquidIonic liquid ratio on the extractionExtraction of scandiumScandium from a synthetic scandiumScandium oxide (Sc₂O₃) system was studied. The influence of investigated parameters on leachingLeaching was very significant as approximately 98% scandiumScandium was extracted from its oxide after 72 h. Furthermore, the ionic liquidIonic liquid also selectively extracted 47% scandiumScandium after 48 h from a mixture of pure metal oxides containing oxides of tantalumTantalum, niobiumNiobium, and scandiumScandium. The research demonstrated the potential of [Hbet][Tf₂N] to selectively extract scandiumScandium from columbite processing tailings and other scandiumScandium bearing ores like Ixiolite, Heftetjernite and Tantalite which predominately contain tantalumTantalum and niobiumNiobium.

Residues from titaniumTitaniumsmeltingSmelting tend to contain scandiumScandium. The scandiumScandium is discarded because no suitable process exists for its recoveryRecovery from the residue. Valuable-metal recoveryRecovery from discharged residue is critical for environmental conservation and to achieve a sustainable society. Since 2015, JX Nippon Mining & Metals has been developing a process for scandiumScandiumrecoveryRecovery from the residue of a titaniumTitanium-smeltingSmelting process. The process consists of the following steps: scandiumScandium concentrating by classification or neutralization, selective scandiumScandiumleachingLeaching, impurity removalImpurity removal by neutralization, solvent extractionSolvent extraction of scandiumScandium by using D2EHPA, purificationPurification, and roasting. We optimized the above steps to achieve an effective process to obtain scandiumScandium oxide (Sc₂O₃). In this paper, we introduce results from the bench-scale test of the scandiumScandiumrecoveryRecoveryflowsheetFlowsheet developed by JX Nippon Mining & Metals.

There are at least a dozen methods of selectively removing cerium from a mixture of the rare earth elements (REE)Rare earth elements (ree) including separationSeparation techniques based on the oxidationOxidation of cerium to the quadrivalent state. Several of the oxidationOxidation processes have been operated on a commercial scale, others have been tested and in some cases are part of proposed flowsheets. In this paper, we describe and compare the various methods. We also present preliminary estimates of the costs of early Ce removalRemoval and discuss recoveryRecovery and purity aspects of the options.

In order to prepare a more desirable feedstock for a rare earth elementsRare earth elementsseparationSeparation refinery, cerium, a penalty element in the refinery feedstock, should be removed from the mixed rare earth elementsRare earth elements oxide or carbonate feedstock. In this study, cerium (III) to cerium (IV) oxidationOxidation by calcium hypochlorite and subsequent precipitationPrecipitation was used to remove cerium from a mixed rare earth elementsRare earth elementschlorideChloride solution. A factorial design of experimentsDesign of experiments was used to determine the effect of process variables such as temperatureTemperature, pH, and oxidizer addition on the oxidationOxidation of cerium (III) using synthetic solutions. Under certain test conditions, all of the cerium was successfully removed from the chlorideChloride solution, and some REERee accompanied cerium and reported to the precipitate. This proposed technology can allow for low cost removalRemoval of cerium from mixed rare earth elementsRare earth elements chlorides.

Solvent extractionSolvent extraction technology using EHEHPA (2-ethylhexyl phosphonic acid, 2-ethyhexyl mono ester) is the norm for industrial separations of rare earthRare earth elements. This process has some shortcomings, including a large number of stages compared to most SX processes and high acid requirement for stripping of the heavy rare earths. In this work, we examine a number of alternative mixed solvent extractionSolvent extraction systems: (i) Mixtures of organophosphonic and phosphinic acids such as EHEHPA/Cyanex 272 or Cyanex 572; (ii) Ionic liquidIonic liquid mixtures of EHEHPA with quaternary ammonium chlorideChloride (Aliquat 336); and (iii) Mixtures of carboxylic acids for yttrium/lanthanide separations. We discuss and compare the efficacy of these systems with reference to the Nd/Sm separationSeparation, which is of industrial significance. Based on the extractionExtraction chemistry and the use of modelling tools to define the counter-current solvent extractionSolvent extraction circuit, we present a techno-economic analysisTechno-economic analysis of a separationSeparation plant and discuss the impact of various solvent systems on the capital expenditure (CAPEX) and operating costs (OPEX).

The production of rare earthRare earth elements from oreOre usually consists of three steps; the separationSeparation of a concentrate of REE bearing mineralsMinerals; the cracking of the REE mineralsMinerals to liberate the REE into an aqueous solution and separationSeparation of REE into individual elements. This paper describes the results of laboratory tests conducted on a carbonate-rich REE ore containing bastnaesite and monaziteMonazite. The tests cover the whole processing sequence of beneficiation, preparation of the REE solution using a caustic leachLeach followed by acid leachAcid leach to break monaziteMonazite and bastnaesite and liberate REE into an aqueous solution and the partial separationSeparation of the REE using solvent extractionSolvent extraction. Details on the product quality and process performances (recoveryRecovery and impurities removalRemoval) are given for each studied step. The paper also discusses the economic advantage of separating the REE rather than producing a mixed REO product to be sold to a refinery for REE separationREE separation. A mini-pilot plantPilot plant version of the process is currently planned.

Rare earth elementsRare earth elements (REEs) are critical materialsCritical materials in many leading-edge technology products. However, REE separationRee separation outside China has remained a challenge in addressing environmental concerns of current production. The author has worked on a technique employing the emphasised variability in the electrophoretic mobility (μ_i) of REERee for the purpose of REE separationRee separation. In continuation of the results presented in IMPC 2016 [1], this contribution summarizes the progress achieved in 2016 and 2017. The major goal was to increase the REEs concentration by a factor of 1000 and to attenuate the consequent drawbacks, specifically joule heating effect. Amphiprotic hydroxylic solvent was selected to replace water, which has a major impact on the complexation mechanism and buffer requirement. Non-aqueous mediaMedia result in a significant drop in the specific molar conductivity of the electrolyteElectrolyte, whilst μ_i reduces several times only. Moreover, a quasi-steady state electrophoretic separationSeparation in conjunction with temperature gradient focusingTemperature gradient focusing is adapted to improve scalability.

The separationSeparation of radionuclideRadionuclide during rare earthRare earth element (REERee) production is an important requirement for developing the Canadian REEReemining industryMining industry. SeparationSeparation of actinides from REERee is often a large concern in the rare earthRare earth industry because of the need to manage the radioactive nuclides. A patented process developed for actinides extractionExtraction from radioactive wastes was applied to REEReeoreOre. Objectives were to optimize the process for REEReeleachingLeaching from oreOre, and separate radioactive impurities from sulphuric and nitric liquorLiquor by ion exchangeIon exchange (IX). OreOreleachingLeaching was optimized using a surface response planSurface response plan to ensure statistical significance. In optimized conditions, solubilization yields ranged from 90–95% for Th, 60–75% for UUranium, 48–55% for LREE, and 59–75% for HREE in sulphuric and nitric mediaMedia. Both mediaMedia were compared for radionuclideRadionuclideremovalRemoval from rich REERee-bearing mineral liquorLiquor by IX. Actinides separationSeparation ranged from 92–97% for Th and 69–96% for U in sulphuric and nitric mediaMedia.

Lack of basic knowledge on the semi-direct recyclingSemi-direct recycling methods for hard metals hinders the application on an industrial scale. However, advantages like reduced expenses and lower environmental impactEnvironmental impact draw interest at future potentials. Consequently, this report aims to offer insight into the influence of varying bulky hard metalHard metal substrates during their lixiviation in acidic mediaMedia with an oxidant. The statistical software Modde 11 assisted in the development of a design of experimentsDesign of experiments (DOE) for evaluation of the impact of average grain size, binder and tantalumTantalum carbide (TaC) content on the leachingLeaching characteristics. The other experimentalExperimental parameters were constant. Among them were temperatureTemperature, solution concentration and quantity, duration and substrate surface exposed to liquid volume. Eventually, prediction plots and factors of the computed modelModel equation describe the effects of varying substrate qualities on leached binder metal and selectivitySelectivity.

In this study, a hydrometallurgical process was evaluated for the recoveryRecovery of Nd from a Nd-Fe-B magnet. Each leachingLeaching test was performed at the solid (weight) to liquid (volume) ratio of 1:50 and was mixed at 400 rpm at ambient temperatureTemperature. The effects of 3 different acids (HCl, HNO₃, and H₂SO₄) on the extractionExtraction of Nd were investigated and H₂SO₄ was found to be more effective than other acid solutions. Under the optimal conditions, pregnant leachLeach solution was produced with H₂SO₄ for subsequent Nd precipitationPrecipitationtestingTesting. Each precipitationPrecipitation test was carried out using 100 mL of feed solution mixed at 600 rpm at 25 °C. NaOH and H₂C₂O₄ were used for Nd precipitationPrecipitation. The highest Nd was precipitated as Nd₂(C₂O₄)₃·10H₂O with C₂H₂O₄ at 20 min.

There are many scales of innovation in the pursuit of concentrator performance improvement, including paradigm change, inventive change and incremental change. All are important, but the last is low risk, low cost and has a relatively high probability of success, given the right metallurgical skills. Seeking continuousContinuous improvement is also essential to ensure that performance does not decline over time due to ore type changes, personnel changes, equipment wear and other factors. When properly implemented, these small gains offer a very high rate of return for the project cost because they are made from marginal, not total, operating costs of the plant. To be effective this approach requires plant trials that use designed structure and appropriate statisticsStatistics to test the observed differences arising from the old and new process treatments, be they a change in flotationFlotation reagent, in grind, pulp density, etc. However the pursuit of small but financially significant performance gains is often regarded as fruitless because of the range of variance in plant data, and the consequent difficulty of ‘proving’ that a benefit has been achieved. Opportunity for improvement is thus sometimes relegated to the realm of the impossible, or at best, treated with skepticism. Operations managers prefer to look for the larger gains, which are easier to demonstrate and prove. Unfortunately, these are seldom to be found; rather, a large gain can be more easily made by executing a series of small recoveryRecovery improvements that are together equivalent to the ephemeral single large gain. In this paper we advocate a policy of continuing improvement driven by rigorous performance testingTesting protocols and a formal ‘risk analysis’ approach to judging the efficacy of changes implemented in the plant. Following these simple procedures allows rational decisions to be made on the basis of quantifying risk and reward. In particular we consider the choice of hurdle rate for decision-making which best balances risk and reward. It is shown through case studies from actual industrial practice that this approach is practical and delivers significant financial value to the operation.

The Cripple Creek and Victor GoldGold Mine was acquired by Newmont in August 2015. The high grade flotationFlotation mill project was commissioned in February 2014. The mill to date has been throughput limited due to mechanical and design issues. In order to create the most value from a throughput limited plant a campaign to provide timely ore characterizationCharacterization was undertaken. A diagnostic leachLeach methodology was developed to determine goldGold associations by ore type. The resulting associations were then used to characterize feed blend; goldGold losses and optimize goldGold production. The diagnostic methodology is presented along with discussion on flotationFlotation implications.

Contrary to other sulfideSulfidemineralsMinerals, where recoveryRecovery is principally liberationLiberation controlled, the recoveryRecovery of molybdeniteMolybdenite is more complex. It is this complexity that initiated a geometallurgical investigation of molybdenitesMolybdenite from Bingham Canyon. The aim of this investigation was to determine the effect mineralogyMineralogy and/or mineralogical attributes have on recoveryRecovery. All samples were analyzed using normal mineralogical techniques. The results reveal the presence of two distinctly different types of molybdeniteMolybdenite. These have been identified as the two polytypes of molybdeniteMolybdenite: i.e. hexagonal (2H); and rhombohedral (3R). The 2H-polytype occurs as textbook-shaped particles in quartzQuartz-molybdeniteMolybdenite veins that are located in the current pit bottom. The 3R-polytype occurs as disseminated, “ball”-shaped particles with a dull or frosted appearance and are concentrated along the margins of the current pit. Concerning their metallurgical behavior, each type exhibits unique metallurgical properties that are consistent with those reported in the published literature. The 2H-polytype is easily ground and kinetically “faster” floating with surface attributes that are amenable to higher rates of recoveryRecovery. This results in the production of a high quality concentrate under normal operating conditions. The 3R-polytype, by comparison, is difficult to grind and kinetically “slower” floating with surface attributes that are less amenable to recoveryRecovery. Therefore, in deposits with higher concentrations of the 3R-polytype, modifications to the normal operating parameters may be necessary to improve recoveryRecovery. This investigation highlights the necessity for understanding the mineralogical characteristics of any economic mineral(s), as these will have a direct impact on recoveryRecovery.

FlotationFlotation circuit performance has become increasingly more challenging due to the complexity of available oreOre sources. To optimize value mineral recoveryRecovery, the mineralogical composition of the oreOre should be evaluated and understood. Utilizing a variety of mineralogical and analytical tools, flotationFlotation processing challenges can be overcome and potential limitations understood. In this paper, several case studies will be discussed in terms of the value that has been provided through the use of mineralogical analysis to optimize flotationFlotation performance.

The formulation and use of mixed collector suites in sulphide flotationFlotation can be traced back as far as 1957 with the work of Glembottskii and his co-workers in Moscow. The subject was reviewed by Lotter and Bradshaw in 2010, and proposed a synergy between ideally-selected different reagent types to deliver improved performance, in particular the in situ catalysis of a xanthate to dixanthogen by a dithiocarbamate. Correctly formulated for a particular application, an optimally arranged mixed collector suite delivers the following improvements to the flotationFlotation process:An increase in the flotationFlotation kineticsImprovement in coarse, or middling, particle recoveryRecoveryReductionReduction in total dosage requirementBest results are found from testingTesting the ratios of the collectors. This is of critical importance.In all an optimally formulated mixed collector system usually delivers an increase in paymetals recoveryRecovery of 1–4% absolute, with a gain in concentrate grade in the range 10–20% relative. In recent years, the addition of semi-conductor theory and associated electrochemistryElectrochemistry has contributed significantly to this toolbox by way of identifying optimum domains of Eh and pH for the flotationFlotation of individual mineralsMinerals. In the case of mixtures of mineralsMinerals, this is where the mixed collector system delivers significant value by way of presenting a mixed set of collector radicals and dimers in a common Eh and pH domain for overall performance. This calls on a fundamental understanding of organic chemistry, mineralogyMineralogy, semiconductor theory, and electrochemistryElectrochemistry. Whereas the selection of grinding mediaMedia type effectively influences the Eh, the pH can be easily controlled by pH modifiers. The theory of this system, and some industrial case studies, are discussed.

Sodium silicateSodium silicate(s), also known as “water glass”, are one of the oldest and most widely used industrial chemicals. Its first use in Canadian operations can be traced back to around 1925, which coincided with early use of xanthates in mineral flotationFlotation. Silicate functions as a sulphide and non-sulphide gangue mineral dispersant, depressant and modifying reagent in grinding and flotationFlotation operations. It is believed that soluble sodium silicateSodium silicate promotes selectivitySelectivity of value added sulphides against gangue mineralsMinerals, resulting in both grade and recoveryRecovery improvement. This paper seeks to link improved grade/recoveryRecovery to the interaction characteristics of mineralsMinerals and the sodium silicateSodium silicate. A systematic study was performed with individual mineral species, an artificially designed modelModel ore and the feed ore from a copperCopperflotationFlotation operation. The function of sodium silicateSodium silicate was evaluated in the context of colloidal chemistryColloidal chemistry and linked to mineral surface chemistrySurface chemistry. Measurement of pulp rheology and mineral zeta potential identified that sodium silicateSodium silicate works as a dispersant. The dispersion is accomplished by increasing a mineral’s net surface charge, resulting in a change in slurry viscosityViscosity. Bench scale laboratory flotationFlotation tests suggest that better dispersion leads to a diminished interaction of chalcopyriteChalcopyrite with gangue. The improved Cu grade and recoveryRecovery then are likely in response to an increased accessibility to collector along with a linked increase in particle bubble attachment resulting in better separationSeparationefficiencyEfficiency. ToF-SIMS surface chemical analysis of the flotationFlotation samples found a higher proportion of sodium silicateSodium silicate on mineralsMinerals from the flotationFlotation tailings relative to the concentrates. Moreover, attachment of sodium silicateSodium silicate appears to be mineral specific; the data indicates that sodium silicateSodium silicate favours the surface of gangue phases over the value sulphides.

Mineral froth pumping utilising centrifugal slurry pumps is a major engineering challenge for the end users and pump manufacturers due to the undesirable outcome of unstable pump performance. Most of these challenges occur due to incorrect pump selection and suction tank design. The traditional approach is to oversize the pump for pumping mineral froth. New horizontal slurry froth pump designs offer opportunities to improve the mineral froth with challenging (high) Froth Volume Factor while maintaining high efficiencyEfficiency, long wear life and stable pumping performance. This paper examines the flotationFlotation process in detail and how froth pumps are designed to handle this arduous process.

The chalcopyriteChalcopyrite-molybdeniteMolybdenite (Cu-MoMo) flotationFlotation industry is increasingly turning to organic depressantsDepressants as suitable replacements for inorganic reagents, such as NaHS, due to environmental and safety concerns as well as high consumption rates of the inorganic reagents. This presents an opportunity for improvements or design and synthesis of alternative reagents. Disodium carboxymethyl trithiocarbonate (Orfom® D8) depressant is an organic depressant with a carboxylate group on one end and a trithiocarbonate group at the other end. Fundamental results are shown regarding the interaction of the Orfom®D8 depressantOrfom® d8 depressant in the bulk flotationFlotation of a Cu-MoMo concentrate from an operating North American mine. Cyclic VoltammetryCyclic voltammetry on pure copperCopper and Fourier Transform Infrared SpectroscopySpectroscopy (FT-IRFt-ir) and X-ray Photoelectron SpectroscopySpectroscopy (XPS)Xps measurements on pure chalcopyriteChalcopyrite with Orfom® D8 depressant treatment are also reported. Through such characterizationCharacterization techniques a potential adsorptionAdsorption mechanism of Orfom® D8 on the mineral surface was identified and its depressant characteristics in the Cu-MoMoflotationFlotation systems explained.