Ni-Co 2013

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In 2011, the US Department of Energy declared cobalt a critical metal, one of 15 such metals deemed to be indispensable but in a risky supply situation in the near future for the production of clean energy.Because of the uncertainty surrounding the supply of primary cobalt from Central Africa, it is more and more imperative to improve the recycling of cobalt from its various uses.This paper reviews methods to recycle cobalt from the scraps of various alloys, from spent rechargeable batteries or spent catalysts and from metallurgical residues, presenting both actual and suggested processes.

Alkali addition for iron precipitation, associated with sulfuric acid leaching of nickel laterites, has been considered periodically since the late 1960s, shortly after the development of the jarosite process for iron control in zinc refining.In the late 1990’s a series of flowsheets were proposed and tested involving simultaneous atmospheric leaching, iron precipitation and acid regeneration. These were considered particularly suited to sequential leaching of limonite and saprolite ores. A number of laterite sulfuric acid leaching processes utilising this chemistry have been put into commercial operation.

Primary nickel is produced from both lateritic and sulfidic ores. Lateritic ores are formed by prolonged weathering of ultramafic rocks. The laterite deposits exhibit graded layers of ore, with high iron, low nickel ore on top and low iron, high nickel ore below. The low iron (< 15 % Fe) ores containing 1.7 — 2.3% Ni are treated by pyrometallurgical processes to produce ferronickel or matte. High iron (> 35 % Fe) limonitic ores can be treated by high pressure leach using sulfuric acid. An alternative process for the production of base metals (Ni, Co and Fe) from both high and low iron laterite ores is being developed by Process Research ORTECH Inc. (PRO), a world leader in the development of chloride metallurgy. The process flowsheet developed by PRO is efficient and environmentally friendly. Novel leaching and solvent extraction separation steps have been developed to make this alternative more economically attractive in the current market conditions.

This study was carried out on a limonitic latente from New Caledonia. The main objective was to evaluate the atmospheric leaching of the ore in ammonium sulphate media using ferrous sulphate as reductant. Different parameters were examined, such as total ammonia concentration, temperature and ferrous sulphate concentration. At 80°C, 130 g/l of total ammonia, 2.73 g FeSO4/ g ore and pH 8.2, nickel extraction was 64 % while 20 % of cobalt remained in solution after 8 hours.

In the atmospheric acid leaching process of low-grade nickelferous laterite, the leaching mechanisms still remain unclear when sulfuric acid is used as the leaching agent. It is therefore imperative to study the leaching characteristics of Ni-doped goethite. In this work samples of goethite and nickeliferous goethite were synthesized and characterized by chemical composition, surface area and XRD analyses. The results show that part of nickel is incorporated into the lattice of nickeliferous goethite. The synthesized nickeliferous goethite was pre-leached in diluted hydrochloric acid at 25°C to separate the adsorbed nickel. Subsequently, the Ni-doped goethite in which nickel is completely distributed within the lattice was leached in sulfuric acid. The results indicated that the extraction of Ni was incongruent with that of Fe. Sulfuric acid leaching kinetics of Ni and Fe are characteristic of chemical reaction and internal diffusion controlled processes, respectively.

Crushed ore agglomeration has been used and is considered as a pretreatment step to improve heap leaching performance of complex copper and gold ores. It is well known that proper agglomeration can prevent solution channeling and ponding, improve percolation within the heap and increase metal recovery rates. However, not much is published regarding nickel laterite agglomeration behavior. Agglomerate size distribution and bed permeability are important parameters to evaluate the quality of agglomerates. With proper considerations, electrical conductivity can be used to control the agglomeration conditions. In this study, a nickel laterite ore from Piaui, Brazil was agglomerated and subjected to different tests to evaluate agglomeration conditions. The study included determination of agglomerate size distribution, saturated hydraulic permeability and electrical conductivity response. It has been found that moisture content and acid concentration have opposite effects on the agglomerate size. Also, retention time and drum rotation speed have small effect on agglomerate size. As expected the permeability of the agglomerate bed is strongly correlated to agglomerate size. Electrical conductivity of the agglomerate bed is affected by agglomeration size, moisture content, acid concentration, and external compaction.

Acid mist abatement in base metal electrowinning cellhouses has advanced rapidly over the last 15 years as a result of both occupational health and economic pressures. Enablers include evolving designs and improved materials of construction. Cellhouse designs now typically include addition of surface tension modifying agents, cell hoods, and anode bags or anode skirts to reduce acid mist production. Automation is increasingly being considered to remove operators from the acid mist containing environment. In nickel electrowinning, chloride based anode bag technologies for chlorine recovery has been adapted to sulfate based systems. These improved technologies and design trends have resulted in cellhouse operating conditions giving greater operator comfort, while also achieving higher operational efficiency.

The Boleo process of Minera y Metalúrgica del Boleo recovers cobalt from a complex oxide and sulfide ore. Following the recovery of copper and zinc products, cobalt is recovered by solvent extraction and electrowinning. The electrowinning process is conducted in a diaphragm cell in a sulfate medium. Cobalt is deposited on a coated stainless steel mandrel cathode with exposed circles to allow plating as disk shaped deposits over the surface of the cathode which can be easily stripped after 5–7 days of deposition. The bench-scale development work on cobalt electrowinning is presented, including selection of plating conditions and additives to control the cobalt disk morphology and pitting behaviour. The cobalt deposit internal stress and the conductivities of CoSO₄-Na₂SO₄-H₂SO₄ system were measured.

In normal practice, the design and sizing of intercell contact bars (ICCB) for electrowinning is based on previously used designs, empirical testwork, or rules of thumb, rather than from first principles. A major operating cost for electrowinning is power consumption. The ICCB is responsible for a portion of the power costs due to its electrical resistance, which comprises electrode contact resistances and the bulk resistance of the ICCB.This paper presents the methods used to calculate the electrical resistances and the results for a number of different widely accepted ICCB designs currently used in electrowinning plants. The paper also makes comparisons between the systems on other key parameters for ICCB performance in nickel and cobalt tankhouses.

Modern nickel electrowinning from sulfate electrolytes is beset by several processing challenges. This includes the need to operate a covered divided cell to minimize nickel mist emissions and ensure nickel plating. Electrometals’ electrowinning (EMEW®) technology overcomes these challenges through the modified geometry of its revolutionary cell design. The EMEW® system exploits a higher solution flow rate in a sealed tubular cell. In this paper, data from commercial scale cells will be presented demonstrating the plating of high purity nickel from lower nickel tenor solutions at higher current densities while eliminating the need for diaphragms. Additionally, the EMEW® design consists of enclosed, round cells, which has the dual benefit of maintaining a healthier, cleaner work environment, as well as producing coherent, tubular cathodes. The cylindrical shape of the cathodes makes them easily harvestable, and also mitigates the effect of the well-known internal stresses inherent to nickel electrowon from sulfate solution.

In electrowinning and electrore fining operations, the detection of operational issues associated with electrode currents has long been a highly labour intensive reactive operations task. The Hatch HELM tracker™ system is set to change the way tankhouses are operated with its ability to measure and record the current flow of every cathode and cell voltage in real time. This information is then presented to provide the ability to identify shorts, poor contacts, and any uneven current distribution. Benefits expected include increases in current efficiency, and thus reduction in operating costs, or increases in production. The software also facilitates simple management of cathode inspection/straightening, stripping and cell cleaning cycles.Hatch has been demonstrating the robustness and performance of the HELM tracker system at commercial copper electrowinning plants. This paper describes the development of this exciting new technology and the expected benefits to the electrowinning and electrorefining industry with specific coverage of its application to the electrowinning of nickel and cobalt.

In 2006, Hatch was awarded a contract to supply fluidized bed technology for the Katanga Mining Limited (KML) copper-cobalt processing project in D.R. Congo [1]. The new roaster and the associated solids and off-gas treatment plants are part of the revitalization of an existing facility, which was historically one of the largest cobalt and copper producers in the world. The sulphide ore fed to the roasting plant is treated under sulphating roast conditions, followed by hydrometallurgical extraction. Equipment for the first roasting line has been installed and the plant commissioning completed. Hatch’s Fluidization Technology Group (FTG) in supplied its proprietary equipment and technology to KML under a license agreement. Our offices in Canada and South Africa conducted most of the required engineering. Here, the process conditions for the sulphating roast, with emphasis on cobalt and copper recoveries are discussed.

The reduction and magnetic separation of low-grade nickel laterite was studied at varing temperatures between 1325–1400°C and a weak magnetic field of 100 mT in order to acquire high grade concentrations. The influence of reduction temperature, percentage of CaO, and atomic ratio of C/O (carbon/oxygen) were investigated. According to the gas analysis, the reaction process was divided into two stages: the direct reduction had a greater advantage than the indirect reduction in the earlier stage when the temperature was low, and the direct reduction and the indirect reduction reacted together in the later stage when the temperature was high. The result indicated that reduction temperature of 1375°C, percentage of CaO of 12% and atomic ratio of C/O of 1.2, the grade of fine ore was improved up to 5.71%. At the same time, the recovery rate of nickel reached up to 96.35%).

This study is a result of a collaboration between Stillwater Mining Company and RHI AG aimed at the determination of refractory products to improve the lining life in the customer’s vessel by using optimized corrosion testing methods at RHI’s Technology Center.As a first part of the work a complete chemical and mineralogical characterization as well as FactSage calculation was carried out based on provided slag samples. According to these results the rotary kiln tests were realized at different process temperatures with several selected magnesia-chromite- and alumina-chromia bricks. Based on the mineralogical investigation a high chemothermal load caused by the Ca-ferritic slag resulted in a deep-reaching infiltration of the brick micro structure and corrosion of main brick components. On the basis of this outcome the selection of suitable brick types will be described in detail in the following article.

The largest cobalt ore reserves are located in DRC, the Democratic Republic of Congo. Most of the cobalt is observed as black cobaltic oxide minerals: heterogenite [HCoO₂] and asbolane [(Ni,Co)₂-xMn(O,OH)₄.nH₂O] which are hardly differentiable since they exhibit similar macroscopic habit and textures. These minerals are frequently observed in similar environment (oxidized horizon of ore deposits) and they are commonly poorly-crystallized limiting their study with XRD. Their chemical composition is also not very well-constrained since they exhibit significant chemical substitutions with cations as Cu, Co, Ni and Mn. The difference in mineralogy and chemical composition of the different cobalt minerals will have an impact on their hydrometallurgical treatment. We compared the natural chemical variability of heterogenite, with that of asbolane samples from DRC. These minerals are compared by EDS and Raman microspectrometry techniques. We show that Raman microspectrometry is a quick and reliable tool to discriminate asbolane from heterogenite.

Recent process development work for the recovery of copper, nickel, cobalt and precious metals (Au, Pt, Pd) from PolyMet’s NorthMet deposit is described. The process uses a number of flotation process steps combined with hydrometallurgical treatment to produce a range of possible products including copper and nickel flotation concentrates for custom smelting, mixed nickel and cobalt hydroxide for refining and a precious metal precipitate for treatment.

The first commercial application of bioleaching in Europe is the Talvivaara Sotkamo Mine in Finland. The ore contains low grade sulphide minerals. Utilization of the deposit has been extensively studied for over 20 years. Bioheapleaching technology was chosen for the extraction of nickel from the ore based on its favorable capital, operational costs and good performance data obtained in a large on-site pilot trial.Building of the industrial scale plant was started in 2007 and metals recovery started in 2008. In full production the annual nickel production will be approximately 50,000tpa. In addition, the mine will also produce zinc, copper and cobalt.Talvivaara will start to recover uranium from the PLS solution. A novel solvent extraction process will be used to extract uranium for the yellowcake production. An update of the existing operation, uranium extraction and the plans for the production expansion and upgrading beyond the 50,000tpa will be discussed.

The world’s proven nickel resources are about 113 million tons, less than 30% for sulfide, more than 70% for nickel laterite, while only approximately 40%) of current production is derived from laterites in both limonite and saprolite. In this paper, the sintering character of limonitic nickel laterite with high iron and low silica was studied to offer technical support for producing Ni pig iron through sintering-blast furnace route. The results show that such minerals generally containing water up to 27~35%>, pre dehydration is very necessary before sintering, The TGA (Thermogravimetric Analysis) and DTA (Differential thermal analysis) revealed removed rules of adsorbed water and crystal water in the minerals. XRD demonstrated that host minerals of the iron-enriched and magnesium depleted version of laterites are mainly ferric iron oxides, typically goethite, FeO(OH). Nickel embedded in the mineral is mainly as the pattern of NiO. The sinter strength of such minerals of sintering is poorer with drum index below 75%, additives can significantly improve the quality of sinter with the drum index increased to 77% or more. The paper also studied the material ratio, sintering temperature and other factors influencing the quality of sinter, while a series of crystal structure changes and mineralogical formation of sinter were also elucidated.

A direct smelting process has been developed at CSIR-National Metallurgical Laboratory, to recover all four valuable metals such as Ni, Co, Cu and Mn. Initially sea nodules containing 1.1% Cu, 1.15% Ni, 0.76% Co, 22.3% Mn, 5.5% Fe and 13.1% SiO₂ was smelted in presence of coke to produce an alloy rich in Ni, Co, Cu and Fe. Various parameters such as amount of coke, quartz, smelting temperature and holding time etc. were optimized on different scale between 0.5–20 kg scale. Under optimized condition, the alloy of composition: 16.% Cu, 18.4% Ni, 1.2% Co 57.0%) Fe and 3.6% Mn was produced on 20 kg scale using 7% coke with more than 90% metal recovery. The process was further up-scaled to 250 kg where similar recovery was achieved with 8% coke and 1 h holding time. The alloy and slag was further processed to recover different value added products.

Water coming in contact with liquid metal is well understood in the metallurgical industry to be an extreme hazard and historically has been at the root cause of many fatal incidents world wide. A wide range of alternative heat transfer fluids exist, which can be used to replace water in both common and special high performance applications. These fluids have a range of physical characteristics leading to different process performances, which can be improved by changes in the configuration and design of the cooling system and furnace cooling elements. This article will examine a number of coolants including natural and synthetic organics, silicones, fluorinated oils, and lead-bismuth eutectic alloy. Peak transient heat fluxes (often where significant damage occurs), Critical Heat Flux and other key copper cooler design parameters will be discussed. Safety tests to determine the suitability of new fluids for use as furnace coolants are discussed and proposed.

Beginning with early lab studies in the 1970’s examining recovery of nickel from slags through to currently operating furnaces treating over 1 million tonnes annually of nickel concentrate, Outotec’s Ausmelt Top Submerged Lance technology has developed to become a viable and proven method of treating nickel bearing materials. This paper covers the technology over the two decades since the first implementation of Outotec’s Ausmelt TSL technology on a commercial furnace. Over this time period, the scale and capabilities of the technology have been greatly expanded. With an increasing focus on the sustainable use of metals with particular interest focusing on utilizing secondary sources, including metal bearing residues, this efficient and flexible technology is ideally suited to increasingly complex and changing feed materials.

Large deposits of low grade mixed Ni/Cu sulphide ores with important PGM values exist in North America and elsewhere. The challenge is producing saleable concentrates at acceptable recovery degrees. Producing bulk concentrates and treating them by Outotec Direct Nickel Flash Smelting (DON) to matte and then hydrometallurgical refining, offers a reliable route from concentrate to product. In the DON process high grade matte with low Fe-content is produced in the Flash smelting furnace (FSF) and metal values in slag are recovered in an electric furnace (EF). Matte refining is based on atmospheric pre-leaching and total pressure leaching. Nickel, cobalt and iron are leached leaving a leaching residue containing small amount of gangue minerals and PGM’s. Iron is removed from the leach solution in an autoclave to produce high quality hematite as by-product. Cobalt and nickel will be recovered with standard methods. Overall > 95% metal recovery can be expected with low energy consumption and low environmental impact.

In this study, Ni-Cr-B alloys were synthesized using a mixture of NiO-Cr₂O₃-B₂O₃ powders reducing with Al powders by a metallothermic process which is a high energy efficient, fast and low-cost production technique for synthesis of cast alloys. Detailed thermodynamical studies were simulated by using FactSage 6.2 Thermochemical software in order to calculate adiabatic temperature of the reactions and effects of initial molar composition on the final products. In the SHS experiments, effects of initial mixture ratios (NiO:Cr₂O₃:B₂O₃) on the metal recovery and compositions of final alloys were carried out. Final products were characterized by using AAS, XRD, EPMA and microhardness techniques.

Blades with excellent high temperature performance are required for industrial gas turbines (IGT). However, defects such as stray grains are almost inevitable, which sharply decrease the properties. Liquid metal cooling (LMC) is used as a new process in directional solidification of large blade castings in recent years, and it still needs to be improved. In order to optimize the casting process, the mathematical models of solidification during investment casting of IGT blade were developed. In this model, the convection between the shell and the cooling liquid metal as well as the influence of the height of liquid metal surface was taken into account. Due to large size of IGT blade, the massive data in the model consumes very much memory and CPU time. A modified FD method is established to reduce memory usage; parallel computing is developed to speed up the calculation. Based on simulation, the temperature and mushy zone evolution could be studied. Validation experiments were carried out. The cooling curves either from experiment or simulation corresponded well with each other.

L605 (equivalent to KC20WN), is a single phase cobalt based superalloy, finding extensive applications in liquid propulsion engines. For optimal performances in service, a uniform fine grained structure is desirable. Controlled thermomechanical treatment was imparted to the material while manufacturing hot forged components. The present paper highlights the influence of the thermo-mechanical treatment on structure and properties of a cobalt based superalloy.

Nickel base cast superalloys exhibits excellent combination of high temperature strength, creep, fatigue as well as oxidation and corrosion resistance and find wide applications in aerospace gas turbine components. Depending upon the severity of environmental conditions in gas turbine, components are cast in equiaxed (EX) or directionally solidified (DS) modes and subsequently heat treated to achieve a wide variety of structure and properties. Accordingly, a study was undertaken to evaluate the performance of a cast Ni-base superalloy and an attempt has been made to correlate processing conditions, structure and mechanical properties. Under similar heat treatment conditions, the directionally solidified material exhibited 15% to 20% superior high temperature strength and creep properties as compared to the equiaxed product. The superior performance of DS material is attributable to more effective solutionizing of γ/γ1 eutectic, absence of interdendritic microporosity and fineness of microstructural features, which can be correlated to the progressive solidification under steep thermal gradient during vacuum investment casting.The present paper highlights the structure property relations in a Ni- base cast superalloy, which was processed in equiaxed and directionally solidified castings, through investment casting route.

Nickel-base filler materials are generally used in applications where resistance to corrosion and heat resistance required. Their description as high-temperature brazing filler materials is amply justified. In this study, nickel boron (NiB) alloys is produced via carbothermic reduction starting from boric acid (H₃BO₃) together with high purity nickel (NiO), charcoal and sawdust by using DC arc furnace which the boron-containing composition of the basic metal is tapped at the bottom. In the arc furnace experiments, different starting mixtures were carried out, and optimum starting composition for producing 15–20 wt. % B containing NiB alloys were investigated. Alloy compositions, metal recoveries, graphite electrode and energy consumptions were performed. The obtained products were characterized by using wet chemical analysis (AAS/ICP), XRD and SEM/EDS techniques.

Several non-ferrous metal ores and concentrates contain significant amounts of arsenic that upon mobilization during hydrometallurgical processing necessitates its effective removal and disposal in environmentally stable tailings. The most common method to accomplish this operation involves lime neutralization in the presence of excess iron. It is known that for its effective co-precipitation, arsenic must be in its pentavalent state and iron as ferric at a molar ratio Fe(III)/As(V)>3. Upon selection of the right pH profile the precipitates produced in this way are stable under oxic conditions. This may be not true however under sub-oxic or anoxic conditions that might develop in tailings ponds. In this context the potential stabilizing role of other co-ions becomes important. As such, this paper investigates the removal and redox stability of arsenic with ferric and various co-ions, Fe(II), Al(III), Ni(II), in a 2-stage continuous co-precipitation process.

Regeneration of hydrochloric acid constitutes a key operation in many new chloride hydrometallurgical processes, including polymetallic Ni-Cu sulfides, laterite ores or extraction of rare earths from apatite ores. For leaching processes that generate a spent calcium chloride solution, one novel option for regenerating HCl involves reaction of CaCl₂ liquor with concentrated H₂SO₄ at low temperatures (T&lt;100°C). Due to the favorable price and availability of sulfuric acid this constitutes a viable option. Therefore, key considerations concern the process kinetics of the crystallization carried out by stage-wise mixing of solutions to control the precipitation reaction, which leads to formation of different calcium sulfate phases depending on concentrations and temperature. Crystal growth and phase transformation kinetics determine the efficiency of required solid-liquid separation steps and optimum residence time in individual process stages. In this paper highlights from our work defining appropriate operating conditions and results from crystallization kinetic studies will be presented.

The state of the art of nickel and cobalt solvent extraction in the nickel laterite industry is assessed, covering the reagents in commercial use (organophosphorus reagents, carboxylic acids, chelating oximes and amines), research developments and chemical fundamentals that result in the different approach taken with each of the reagent types.

The key to preparing high-purity cobalt is purifying of cobalt solution. Cobalt sulfate solution was refined by PC88A levextrel Resins which produced from HPD-100 type of ethylene benzene -divinylbenzene porous adsorption resin and PC88A extractant. The results indicate that under the condition which the solvent impregnated resins containing PC88A is 55% in 065 mm × 700mm chromatography column, extraction pH value is 3.7, buffer elution pH value is 2.9, velocity of flow is 1~1.5 chromatography column volume/h, when solution volume is three times of column volume, stripping solution is collected and stripping by pH 1.0 hydrochloric acid. The high purity cobalt chloride solution is obtained. Removing organic impurity form cobalt chloride solution and concentrating, the high purity cobalt which obtained by electrolyze the cobalt chloride solution is tested by GDMS. The results indicate that the total impurity of twenty elements is less than 10 ppm.

The conventional processing of high grade nickel saprolite deposits is typically by ferro-nickel or matte smelting. Low grade nickel saprolites are not treated. The Caron process for nickel laterite treatment produces residues that still contain significant quantities of un-leached nickel and cobalt. The Starved Acid Leach Technology (SALT) was developed to recover nickel and cobalt from these lean resources. Relatively small amounts of acid are applied to ground laterite or residue in order to selectively leach nickel and cobalt. The leaching is performed atmospherically under low free acid conditions. Nickel and cobalt may be recovered via resin-in-pulp processing or by solid-liquid separation and recovery from solution.

Synthesis of metal powders with tailored characteristics, such as those of Cu, Ni & Co has been the subject of much attention during the past decades. This is due to their potential technological applications in several critical & emerging areas, e.g. in the manufacturing of energy storing devices, optoelectronic and magnetic recording media, high end catalysts, etc. etc. In recent years, nano particles of nickel have found applications as electrodes in multi layer ceramic capacitors (MLCC) due to their excellent electrical conductivity, high melting temperature & low cost [1–3]. Similarly, fine cobalt powders are one of the main constituent for manufacture of rare-earth based permanent magnets [4].