Proceedings of the 62nd Conference of Metallurgists, COM 2023

This study presents the exploratory results on the nickel extraction from a serpentine flotation tailing sample containing sulfide and serpentine minerals at 0.3 wt.% of nickel. The nickel deportment analysis showed that almost 60% of nickel is hosted by sulfur-based minerals and 40% of nickel is in serpentine phase. The major impurities in the tailing are magnesium, silicon, iron with 24.6 wt.%, 15.9 wt.%, and 4.83 wt.% content, respectively. The other base metals in the samples are cobalt and copper at low quantity of 0.01 wt.% for each. The extraction study relates to the atmospheric pressure leaching of nickel at close to ambient temperature (range 35–45 °C) using glycine solution under alkaline conditions (pH = 10). This study also explored the effectiveness of Room Temperature (RT) leaching of nickel for a possible heap leach application. The results show that providing heat is not essential for the formation of metal glycinate complex; however, it improves the kinetics of metal extraction. Different analytical techniques have been applied and developed to analyze the glycine during the extraction. Based on these results, glycine was quite stable during the extraction and can be recovered following the recovery of nickel from the leach solution by using ion exchange (IX) resins.

Flash vessels are used in pressure hydrometallurgy to dissipate the energy of a slurry as it transitions from autoclave conditions to an atmospheric state and to separate the flashed steam from the residual slurry. The energy dissipation is realized through a slurry pool and impingement block that protect the vessel. The pool penetration and energy exerted on the impingement block vary with flow with the most punitive conditions often at reduced flows and not at the maximum flows. Therefore, an optimally designed pool depth requires flow considerations over a wide operational range. Historically, steam rise velocity has been primarily used to optimize separation in flash vessels. Simplistically, the lower the rise velocity, the better the separation and the lower the slurry droplet carryover. While the impact of carryover is site-dependent, it is always undesirable. The Souders-Brown equation, often used to establish design rise velocities, compensates for gas densities at various conditions but does not capture all the relevant physics influencing carryover. Caldera Engineering has performed CFD modeling of flash vessels to optimize flash tank designs and to facilitate troubleshooting in existing operations. During this investigation, it has become apparent there are more factors besides rise velocity that influence carryover. This paper presents the outcome of the modeling and the effect on pool size/depth, as well as how rise velocity, disengagement height, blast tube design, and pool flow dynamics influence carryover.

Pressure oxidation autoclaves for the recovery of gold, copper, and other metals operate at corrosive conditions that require specialized materials of construction. Typical autoclave construction consists of carbon steel pressure vessels lined with acid-resistant membrane and refractory systems. Auxiliary items such as nozzle liners, compartment walls, and baffles utilize titanium or other corrosion-resistant metals. The resulting construction is a composite of several dissimilar materials including ceramics, metals, and polymers. Design and construction of autoclaves must coordinate the specific properties of each material used to provide reliable long-term operation.

The current commercial practice of processing laterite via HPAL consumes significant quantities of acid and generates a large quantity of tailings. In this context, Sherritt has studied a novel process that minimizes the quantity of process tailings generated by producing iron oxide as a saleable by-product.The RAPID Process, a reductive leach process utilizing sulfuric acid and an organic reductant, effectively leaches Ni and Co from both limonitic and saprolitic laterites and generates a high-quality hematite by-product. The hematite by-product is generated from the iron extracted during the reductive leach via a jarosite precipitation step at 170 °C and 500 kPag oxygen overpressure. The jarosite was then thermally decomposed at 800 °C to produce a high-grade hematite product containing 70.1% Fe and <0.1% S. Thermal decomposition of the leach residue allows recovery of input reagents, with more than 99% of ammonia being recovered at 450 °C, and more than 97% of the sulfur being recovered at 800 °C. Nickel and cobalt are recovered from solution via precipitation with hydrogen sulfide at pH 3.5. Using this method, up to 95% of Ni, more than 99% of Co, and less than 3% of other metals were precipitated from the leach solution. A conceptual engineering study was conducted to estimate the RAPID capital and operating costs. While the concept is technically feasible and has been successfully demonstrated at a laboratory scale, its commercial application is deemed not economically viable under current market conditions.

The demand for nickel and cobalt salts for lithium-ion battery manufacture is expected to continue to increase as electrification of the transportation sector accelerates. Nickel concentrates typically are smelted and refined to produce Class 1 nickel products which can be used to manufacture metal salts. Alternatively, a process has been conceived to pressure oxidize nickel sulfide flotation concentrate to produce mixed hydroxide precipitatePrecipitate (MHP) containing nickel and cobalt. MHP is often produced from nickel laterite operations and MHP may be refined to produce battery grade metal salts. The process uses a medium temperature autoclave (150 °C) to extract Ni, Co, Cu from the nickel concentrate into solution. The solution is then purified by pH adjustment with limestone, followed by copper recovery as a copper sulfide precipitatePrecipitate. The purification residue and the autoclave residue form a single combined residue. The copper-free solution then goes through a further impurity removal step for polishing Al/Fe and then into MHP precipitation with magnesia addition. The final product is high-grade MHP which can be used as a precursor to be making battery salts (NiSO4 and CoSO4) for lithium-ion batteries.

The path to carbon neutrality and transition to global clean energy require accelerated CO2 sequestration and enhanced supply of critical metals. Comprehensive utilization of ultramafic tailings is a promising route to achieve these goals since these materials contain abundant suitable minerals for CO2 mineralization and residual critical metals for further recovery. This work presents the accelerated CO2 mineralization and simultaneous critical metal recovery from ultramafic tailings in a single step under elevated temperature and CO2 pressure. Olivine ((Mg, Fe, Ni, Co)2SiO4) is found as the main reactive mineral during the accelerated CO2 mineralization process and as the important source of nickel and cobalt for recovery. Usage of an aqueous solution containing sodium bicarbonate and a suitable ligand (e.g., trisodium nitrilotriacetate (NTA)) can simultaneously achieve CO2 permanent storage and nickel and cobalt extraction from olivine-based mine tailings. The selectively extracted nickel and cobalt in aqueous solution can be recovered through sulfide precipitation as high-value nickel sulfide concentrates. The use of NTA can also significantly accelerate the coupled CO2 mineralization and metal leaching process and minimize the effects of iron content in olivine on the reaction kinetics. The important findings can make important contributions to utilize ultramafic tailings for enhanced CO2 storage and global supply of critical metals toward carbon neutrality and sustainable developments.

Imperial Mining Group Ltd is developing its Crater Lake scandium project in Northeastern Quebec. The Crater Lake Intrusive Complex is a 6 km diameter olivine quartz ferrosyenite deposit within Mistastin Batholith. The metallurgical process being developed includes mineral beneficiation which uses magnetic separation techniques to produce a scandium / rare earth element (REE) mineral concentrate. The mineral concentrate is subjected to a patent-pending two-stage hydrometallurgical extraction process which entails a high-pressure caustic leach (HPC) followed by hydrochloric acid leach of the HPC residue which resulted in 96% scandium extraction. Optimization testing conducted at the laboratory scale included evaluating caustic leach temperature and acidity of acid leach. Following the optimization testwork, 66 kg of concentrate was caustic cracked using a 18.9 L Monel batch autoclave, and the cracked and washed residue was subjected to bulk batch atmospheric leaching.

Forward osmosis (FO) is a sustainable liquid mining process that can be used to concentrate metal-containing aqueous solutions with minimal energy input and allow the recovery of valuable metals. It relies on a semi-permeable membrane to allow the selective and spontaneous permeation of water from a low-concentration feed solution into a high-concentration draw solution. In this work, the results of the application of FO in the liquid mining of lithium from an emulated lithium brine lake using nontoxic aqueous inorganic draw solutions are reported. A flat-sheet cellulose triacetate membrane was used to study the effects of the type (NaCl, CaCl2, and MgCl2) and initial concentration (1.5, 2.5, and 3.5 M) of the draw solution on the final lithium concentration in the feed solution. The latter was found to increase by more than 3.5 times after 1 h, while MgCl2 (3.5 M) as a draw solution showed the highest water flux (4 L/m2/h). Overall, our results indicate a strong potential for FO in liquid mining applications: the concentration of dilute aqueous solutions containing critical and strategic metals, which due to their low concentration cannot be recovered.

Sherritt’s Chimera process was developed to treat high-impurity copper concentrates and nickel laterites together in a single pressure leach step. In this process, oxidation of the sulphide minerals in the copper concentrate provides heat and acid for the leaching reactions, while the limonite or transition laterite ore consumes acid and provides a source of iron to form highly stable leach residues. Copper is recovered as copper cathode from the common leach solution by solvent extraction and electrowinning, while nickel and cobalt are recovered as mixed sulphide or hydroxide intermediates after purification of the copper raffinate. In this study, batch tests were conducted on samples of arsenical copper sulphide concentrates, with varying concentrations of As, Sb and Bi, to determine the effects of these elements on sulphide oxidation and metal extraction from the concentrate and laterite ores. The rate and extent of nickel and cobalt extraction from the laterite were affected by the Fe:As and/or Fe:Sb mole ratio in the concentrate feed and the autoclave retention time. Bismuth did not interfere with the kinetics or extraction of copper, cobalt or nickel up to the maximum level tested. Extractions of over 96% copper and over 95% for nickel and cobalt were achieved from a range of laterite ores and from concentrates containing up to 5 wt% As, 8 wt% Sb and 5 wt% Bi.

In many hydrometallurgical pressure oxidation (POX) processes and almost all high-pressure acid leaching (HPAL) processes, the recovery and efficient reuse of energy from flashed steam in the pressure letdown circuit is an essential element of sustainable process design and economic processing. In whole-ore POX circuits, the use of recovered process steam for preheating feed slurry enables autogenous conditions to be maintained at sulphide grades as low as 1.5–2% w/w S2−. In HPAL circuits, increasing the recovery of flashed steam minimizes the requirement for direct injection of boiler steam to the autoclave, the associated dilution of downstream liquor tenors, and where process steam is generated using fossil fuels, the recovery of flashed steam also reduces the associated carbon footprint.This paper introduces the concept of entropy, Clausius inequality, the second law of thermodynamics, and the use of temperature-entropy (T–s) diagrams to describe the overall thermodynamic efficiency. It explores the benefit of adding multiple stages of pressure letdown and feed preheating, akin to the use of regenerative feed water heating in thermal power plants to improve overall Rankine Cycle efficiency. This paper then shows how this concept may be applied to more complex metallurgical models for POX and HPAL processes, and the impact of non-ideal equipment constraints such as approach temperatures. Finally, this paper examines the benefits of increasing the number of heat recovery stages from 2 to 3, 4, and 5 stages, with the expected reduction in steam and fuel consumption and CO2 emissions for each incremental stage.

This chapter presents the results of ASTM G124-promoted ignition of titanium metal, with two new data sets covering high-pressure oxidation at concentrations of 10% v/v O2 and 20% v/v O2 and a total pressure of 800 psi(g) and one data set covering medium–low-pressure oxidation at a concentration of 40% v/v O2 and a total pressure of 100 psi(g). These data are then combined with promoted ignition test data from previous investigations, with the objective of developing a statistical model for titanium flammability. The statistical model will aid the oxygen system designer in the safe use of titanium materials in elevated oxygen environment services.

This paper reviews selected CSB, OHSA, and MSHA investigations of severe chemical, petrochemical, and metallurgical plant incidents with the objective of identifying examples where one or more emergency isolation valves, if installed and operated successfully, could have minimized the severity of the outcome or averted the incident entirely. It examines some of the root causes of failures of critical isolation valves, actuators, and emergency shutdown systems and identifies the frequency of preventive maintenance and testing measures that can be taken to minimize the probability of failure on demand.

Vale base metals started operating the Long Harbour Refinery in 2014 using a novel hydrometallurgical process (Reference Derek Kerfoot, US patent 6,428,604) to produce high-purity electrolytic nickel, cobalt, and copper, from the (nickel sulphide concentrate produced at the mining operation at Voisey’s Bay. Over the years, many challenges were successfully overcome. A particular area for attention was the pressure leaching circuit, where difficulties with plugging and corrosion of the autoclave discharge dip tubes were frequent. The regular plugging and corrosion of these dip tubes resulted in reduced autoclave availability. In collaboration with Caldera Engineering, supplier of dip tubes, a non-metallic liner was developed and proved successful in addressing the operational difficulties. This improvement resulted in a reduction of unplanned downtime, lower replacement costs, and increased safety. This paper reviews the evolution from problem to solution over the past 5 years of operation.

Vale Base Metals operates the Long Harbour Refinery using a novel hydrometallurgical process** to produce high-purity electrolytic nickel, cobalt, and copper, from the nickel sulphide concentrate produced at the mining operation at Voisey’s Bay. The process is based on controlled partial oxidation of sulphide sulphur to sulphate using oxygen at moderately elevated temperature and pressure, sufficient to achieve high pay-metal extractions. Impurities are subsequently removed from the product pressure leach solution; copper and cobalt are separated from the nickel by solvent extraction, resulting in a high-nickel solution from which nickel metal is produced by electrowinning at high current efficiency. Heat generated from the exothermic oxidation of sulphide concentrate in the pressure vessels is recovered for heating the process buildings. The combination of low-energy intensive hydrometallurgy technology, energy recovery, and utilization as well as the use of hydroelectric power for the plant results in a very low-carbon footprint of the metals produced. This paper will review the low-carbon footprint features of the process and ongoing initiatives to reduce it even further, including electrification of a boiler used to produce process stream. ** Derek Kerfoot was the key driver for the research and development of the novel Pressure Oxidative Leach (POL) with direct nickel electrowinning process, ultimately commercialized at Long Harbour. Through a combination of deep hydrometallurgy knowledge, wide industry experience, persistence, and perseverance, he helped turn a vision into reality.

At Vale’s Copper Cliff Nickel Refinery (CCNR), a solid residue is produced through the INCO pressure carbonyl (IPC) process, which typically contains 50–60% Cu, 5–10% Ni, 4–8% Co, 5–10% Fe, 0.5–1.5% As, and trace amounts of Pb, Bi, Sb, Sn, Se, Te, PGM, Ag, and Au. The IPC residue is treated in the first-stage pressure leach autoclaves at 150 °C to extract 80–95% Ni, Co, and Fe, as well as 30–40% As. As arsenic in the feed concentrate to the Smelter at Sudbury has increased in recent years, the arsenic in the IPC residue, as well as the arsenic in the copper electrolyte and in the leach residue, has been significantly increased. To better understand and improve the extractions of arsenic and other elements in the first-stage pressure leach autoclaves, a test program was conducted at the Vale’s Technology Centre in Mississauga. The results from bench scale testing confirmed that increasing the operating temperature in the first-stage leach autoclave from 150 to 180 °C would significantly improve the extractions of arsenic, nickel, cobalt, and iron. Based on the results obtained in this test program, one of three first-stage autoclaves at CCNR was reconstructed in 2022 to increase its operating temperature from 150 to 180 °C. Commissioning of this reconstructed first-stage autoclave has been scheduled in 2023. This paper presents the results obtained in the lab tests and process development.

Nickel sulphate (NiSO4.6H2O) and cobalt sulphate (CoSO4.7H2O) crystals are key components of precursor cathode-active materials (P-CAM) used in lithium-ion batteries. Following increasing demand in recent years for electric vehicles (EV), there has been an upsurge in the production of nickel sulphate and cobalt sulphate crystals of high purity. Feedstocks for the production of these crystalline materials include various forms of pure metal, concentrates, oxides, and hydroxides. The sulphate hydrometallurgical process plants typically include pressure oxidation, leaching, neutralization, precipitation, solid-liquid separation, solvent extraction, ion exchange, and crystallization. Choice of chemical reagents and their required quantities for these process schemes is a major consideration in the design and operation of sulphate refineries. Provision and application of reagents in the hydrometallurgical plant to meet stringent product grades and in the treatment of effluent streams to meet environmental regulations call for special attention to process chemistry and test work. Potential challenges are the need for optimization and reduction of excessive reagent quantities, reduction of operating costs and adverse impacts of reagent reactions on other process steps, introduction of impurities to process streams and final product, extent of engineering and equipment required for safe introduction of chemical reagents at the various stages of the process, potential availability of reagents in the current supply-chain environment, and handling of by-products. This paper discusses some of these challenges as encountered in several hydrometallurgical process schemes for the production of nickel sulphate and cobalt sulphate crystals and points to possible conceptual process solutions for mitigating the difficulties encountered.

A continuous pilot plant campaign has been conducted over the 2021–2022 period to demonstrate the technical feasibility of Metso Outotec’s novel BIOX® MesoTHERM process for treating high-grade copper-gold concentrates. The concentrate hosted refractory gold, as well as primary and secondary copper sulphide minerals. The pilot plant program was structured such that each hydrometallurgical unit operation in the envisioned full-scale plant flow sheet could be validated. Demonstration of the key features of the MesoTHERM technology which involved the series operation of the mesophile and thermophile biooxidation circuits in continuous mode spanned over a period of several months. The circuit configuration and performance proved that near-complete oxidation of all sulphide minerals was attainable, realizing not only high levels of copper solubilization but also liberating gold for recovery in a downstream cyanidation process. Another key component of the program involved a continuous copper solvent extraction – electrowinning pilot campaign to produce raffinate for recycling to the biooxidation circuits, i.e., to prove fresh acid requirements can be offset. Copper cathodes were also produced during the trial. Ancillary neutralization circuits, as well as solid-liquid separation stages, were investigated in continuous mode to further validate the processing circuits’ feasibility. From the pilot program, sufficient design data may be abstracted to support the engineering of a full-scale plant and allow process performance guarantees to be offered.

Sherritt developed the Dilute Pressure Oxidation (Dilute POX) process for the recovery of base and/or precious metals from high impurity or refractory sulphide concentrates. In this process, the autoclave is operated at a lower slurry solids content than what is required for autothermal operation to control the acidity of the pressure leach solution, with heat recovery used to maintain the autoclave temperature. This study presents the results from treating high-silver refractory gold feeds. Operating under Dilute POX conditions suppressed the formation of argentojarosite, which increased the silver extractions in the direct cyanidation of the POX residue to over 90%, from 0% to 30% under autothermal conditions, while maintaining high gold extractions in cyanidation (>98%) and high sulphide oxidation (>97%) in POX. The relationships between free acid in solution and silver extraction, and between magnesium in solution and effective free acid, were consistent with previous Dilute POX studies with arsenical copper concentrates. With lower sulphate in the solids under these conditions, the formation of basic ferric sulphate was reduced or eliminated, iron and arsenic in solution were reduced, and the majority of the sulphide in the feed was converted to free acid. Based on these results, operating under Dilute POX conditions may eliminate the need for hot curing in POX flowsheets for refractory sulphide feeds, and/or allow for treating feeds with higher carbonate contents.

Solution leaving the nickel reduction circuit at Sherritt’s nickel and cobalt refinery located in Fort Saskatchewan, Alberta, is currently treated with hydrogen sulphide gas to remove zinc, producing zinc sulphide. While effective in removing zinc from this solution, hydrogen sulphide is a safety hazard and represents a significant reagent cost. In addition, some nickel and cobalt coprecipitate with the zinc by-product resulting in unrecoverable losses. These impurities in the zinc sulphide reduce its marketability.As an alternative, Sherritt tested precipitation of zinc struvite (ZnNH4PO4) to replace the current precipitation process using hydrogen sulphide. Lab and piloting test work indicated that dissolved zinc may be precipitated as anhydrous zinc struvite from hydrogen reduction end solution with the addition of diammonium phosphate and ammonia. The implementation of this process may reduce nickel and cobalt losses, reduce hydrogen sulphide consumption on site, and improve zinc marketability. Furthermore, the zinc struvite produced may be heated to convert it to zinc pyrophosphate by-product.

Integrated piloting testwork utilising pressure oxidation, precipitation, solvent extraction, and the re-leaching of mixed Ni-Co hydroxide precipitates was carried out by the ALS Hydrometallurgy Centre of Excellence (HCE) as part of the Ta Khoa Refinery Definitive Feasibility Study (TKR DFS) for Blackstone Minerals. Concentrates from the Ban Phuc Nickel Mine were blended with two third-party concentrates, supporting the TKR DFS.The main objective of the overall flowsheet was to remove impurities to produce battery grade nickel and cobalt sulphate, while maximising Ni and Co recoveryRecovery as a precursor product suitable for EV battery purposes. The key issue in the operation of the autoclave was to control scale formation and maintain sufficient free acid while maximising Ni and Co extractions.This paper presents an overview of the challenges faced in the flowsheet development from batch testwork to continuous piloting of the selected concentrates through the generation of high-purity Ni and Co sulphate solutions from the solvent extraction circuits.

Cerium is the largest constituent of the rare earth elements (REE) bearing ores, accounting for up to 50% of their REE content. As such, Ce is overproduced by the industry in order to meet the demand for less abundant REEs required for advanced applications. Ce removal is the first step in REE purification because the high fraction of Ce lowers the throughput of subsequent steps and negatively impacts manufacturing costs. Most chemical Ce separation methods are based on the low hydrolysis pH of Ce(IV) compared to the other trivalent lanthanides. This work focused on cerium removal from a synthetic mixed REE sulfate solution representing an H2SO4 leach solution. Oxidation of Ce(III) was achieved with hydrogen peroxide (H2O2), followed by precipitation as Ce(OH)4 under controlled pH and redox conditions. Batch tests revealed Ce removal levels between 50% and 90%, and REE losses below 5%, depending on the pH and H2O2 dosage. It was determined that Ce(III) oxidation was the rate-limiting step, while Ce(IV) precipitation was fast and quantitative.

Lithium-ion batteries (LiBs) are increasingly in demand for energy storage and use in electric vehicles. Recycling of these end-of-life (EOL) batteries is considered one of the most effective ways for recovering elements such as lithium, manganese, cobalt, and nickel and circulating them back to the battery materials’ supply chain. However, few articles have been published which discuss the recycling chain, starting from LiBs to the production of battery grade (BG) nickel/cobalt sulfates (which are used to produce pCAM) with CAPEX, OPEX, and timeline estimates. This article summarizes the pretreatment process of LiBs to Black Mass and compares subsequent hydrometallurgy processes to convert Black Mass to BG sulfates, along with high-level summaries of the CAPEX, OPEX, and timelines. Besides, the critical path of project implementation is also presented.

Chalcopyrite is one of the difficult-to-leach minerals as passive films of copper polysulphide form with mild leaching in sulfate media. Also, molten sulfur wets the mineral surface and can also inhibit leaching [1]. Chloride hydrometallurgy could be a viable option for chalcopyrite leaching as it has several advantages over sulfate systems and chalcopyrite does not passivate in chloride leach [2–6]. In this work, copper was extracted from chalcopyrite using a mixture of electrolytes containing relatively dilute HCl and nonassociated chloride salts such as NaCl, CaCl2, CuCl2, FeCl3, and MgCl2 rather than using pure HCl or pure binary electrolytes. This resulted in proton activities as high or higher than those obtained in pure concentrated HCl solutions.

Process modelling is used as a simulation tool for the purposes of design and optimisation. This paper discusses the application of modelling in hydrometallurgical project development and the value it creates by allowing for rapid high-level flowsheet option evaluation, testwork planning and analysis, provision of data for equipment design, and operating plant optimisation. This paper explains the development process for a pressure oxidation model from input data such as throughput, feed composition, and testwork results. Case studies demonstrate the real-world application of modelling for process development.

With the effects of climate change becoming more apparent, countries around the globe are taking unprecedented actions toward lowering their CO2 emissions in accordance with Paris Agreement and United Nations Sustainable Development Goals. Clean energy technologies, however, are more material intensive than its conventional counterparts and will therefore require steadfast supply of metals (e.g., copper, nickel, cobalt) (IEA, Flagship report: The role of critical minerals in clean energy transitions. https://www.iea.org/reports/the-role-of-critical-minerals-in-clean-energy-transitions , 2021). This implies a need for more extensive mining operations for these metals over the next decades to successfully support a rapid clean energy transition scenario.

This research paper describes the efforts conducted for the recovery of Ni, Co, Mn, and V from tailings of spent catalyst recycling operations. The spent catalysts are solid wastes and contain many valuable metals and in quantities that are feasible to extract. Laboratory testwork was conducted for the smelting of alumina concentrate (AC) tails using coke and lime to improve the ratio of valuable metals to AC tails. After smelting, leaching of the alloy was conducted in sulphuric acid solution using hydrogen peroxide, which offers a relatively economical method for metal extraction from the alloy. The laboratory tests performed on several alloys showed that battery metals can be extracted with high recoveries; however, the kinetics of dissolution were slow. OLI modeling tools were used to compare the leaching results.

The emergence of the fast-growing battery-powered EV industry creates huge pressures but also opportunities on metal/material production to meet the accelerated pace of Li-ion battery (LIB) manufacturing as evidenced by the construction of hundreds of “gigafactories” around the world including Canada [1–4]. A characteristic example that illustrates the tectonic transformation triggered by the electrification trend is the case of Umicore, a multinational metals company, which invests heavily in producing nickel-cobalt-manganese cathode materials in their new Canadian plant in the area of Kingston, ON [3]. A recent report by Research & Markets projects the global battery market to grow from US$ 95.7 billion in 2022 to US$ 136.6 billion by 2027. Hydrometallurgy stands to play a major role in this context not only in terms of extraction/recovery of metals like Ni, Co, and Li from primary and secondary sources, but also in the area of production of battery-grade precursors, as well as production and recycling of the active electrode (cathode mainly) materials themselves [5].

Mg-Li-based alloys, being the lightest alloys, are attractive for aerospace applications. We have optimized Li content as 8 wt% and Zn content as 2 wt% in Mg to obtain tensile properties better than the existing commercial and experimental wrought Mg-Li-based alloys, which has been discussed in another paper. In this manuscript, we present the electrochemical corrosion behavior of these two cold-rolled alloys, i.e., Mg-8Li (LZ80) and Mg-8Li-2Zn (LZ82), by open circuit potential evolution, electrochemical impedance spectroscopy, and potentiodynamic polarization test in 0.5 wt% NaCl solution. The microstructure of the alloys was examined by scanning electron microscopy before and after corrosion tests in order to explain the observed corrosion behavior. It was observed that LZ82 alloy exhibits better corrosion resistance than LZ80 alloy. Both the alloys exhibited localized pitting corrosion, but it was less severe in the case of LZ82 alloy. The pitting corrosion was initiated at the interface of α-hcp and β-bcc phases due to micro-galvanic coupling between the two phases, and Zn addition lowered the surface potential difference between these phases, as revealed by scanning Kelvin probe force microscopy.

With superior tensile strength and improved fatigue performance of Silafont®-36 alloy in the as-cast state, this study is aimed to evaluate these properties of the alloy in a T5 heat treatment state, since the use of T5 temper involving only artificial aging without solution heat treatment such as T4, T6, and T7 tempers would significantly reduce lead time and save energy. While the strength of the Silafont®-36 alloy decreased, the ductility increased after the T5 artificial aging at a relatively high temperature of 330 °C, but only for a short time of 30 min. This heat treatment led to cyclic stabilization of the alloy, without cyclic hardening or softening until final failure.

Thermomechanical fatigue (TMF) that resulted from the cyclic changes of stress and temperature is considered to be one of the most detrimental failures for the automotive engine parts. To improve the service life of engine components, it is essential to understand their TMF behavior and hence improve the TMF resistance. In this work, the out-of-phase TMF behavior of Al-Si-Cu 319 and Al-Si-Mg 356 cast alloy was investigated under various strain amplitudes (0.1–0.6%) and cyclic temperature (60–300 °C). In addition, the influence of Mo microalloying on the TMF behavior of Al-Si-Cu 319 alloy was also studied. During TMF cycling, all three experimental alloys displayed asymmetric hysteresis loops as well as the cyclic softening of maximum tensile/compression stress, which is likely attributed to the coarsening of precipitates. The TMF lifetime of the 319 alloy was generally higher than that of the 356 alloy, and the Mo-added 319 alloy further improved the TMF life due to the formation of thermally stable Mo-containing dispersoids. The fatigue life of three experimental alloys was simulated and predicted by an energy-based model, which was in a good agreement with the experimental data.

The evolution of the Mn-bearing dispersoids in two Al-Mg-Mn 5xxx alloys with 3% and 5% Mg and their impact on the mechanical properties and recrystallization resistance have been investigated. A large number of Mn-dispersoids were precipitated in the aluminum matrix by applying a low-temperature homogenization, but the type, size, and number density of these dispersoids after heat treatment were strongly related to the Mg levels: fine Al6Mn and α-Al(Mn,Fe)Si dispersoids were observed in Al-3 Mg-Mn alloy, while the dispersoids changed to relatively large Al4Mn and Al6Mn dispersoids in Al-5 Mg-Mn alloy. The mechanical properties after cold rolling as a function of the annealing temperature were studied. The yield strength after cold rolling and 300 °C annealing reached 233 MPa for low Mg and 253 MPa for high Mg alloys homogenized at low temperature, respectively, showing an improvement of 30% and 20% over the high-temperature homogenization. In addition, the deformed grain structures after cold rolling and annealing were characterized. Results demonstrated that fine and densely distributed Mn-dispersoids generated during low-temperature homogenization could effectively hinder the dislocation and sub-grain boundary migration and improve the recrystallization resistance of cold-rolled sheets.

The homogenization treatment and the contents of Mg and Si can affect the evolution of nano-sized Zr-bearing dispersoids and subsequently the mechanical properties of 6xxx alloys. In this study, two Zr-containing 6xxx alloys with different Mg and Si levels were used to conduct the homogenization at two temperatures (400 °C and 550 °C). The hot extrusion process was applied to the homogenized billets to produce flat bars. The evolution of Zr-bearing dispersoids was investigated after homogenization and extrusion using transmission electron microscopy. In addition, the mechanical properties of as-extruded and T5-treated samples were evaluated. The results showed that a higher number density of finer Zr-bearing dispersoids was formed at lower homogenization temperatures. The number density of dispersoids was higher in the case of the high Mg and Si alloy. A fibrous deformed grain structure was obtained after extrusion for the samples homogenized at 400 °C in both Zr-containing alloys. In contrast, homogenization at 550 °C resulted in a fully recrystallized grain structure. In the dilute Mg and Si alloy, homogenization at 400 °C produced higher tensile strengths compared to homogenization at 550 °C. However, the homogenization condition had almost no effect on the tensile properties of the high Mg and Si alloy.

High process control and product quality standards in industry and scientific research demand exact temperature determination for metallurgical systems. In many cases, reliable information can be obtained via thermocouple measurements. Still, this option is unfeasible for technologically advanced processes such as consumable vacuum arc remelting due to technical reasons, for example, high temperatures, aggressive melts, or demand for melt cleanliness. Those circumstances necessitate contactless infrared measurement to ensure accurate and non-invasive results. Determining thermal emissivity, the harsh environment, and the dynamic of liquid surfaces in the process are challenging conditions for infrared thermography in metallurgy. However, in return, it allows measuring online with high resolution in time and space at the surface of a metallurgical process, quantifying the amount of superheating or temperature development over time and to detect phases with different thermal emissivity, like slag on metallic phases. This information can be used to increase simulation accuracy, microstructure prediction, as well as process control and comprehension. The study introduces IR-thermography for metallurgical applications with practical examples and demonstrates its successful implementation in a titanium alloy consumable electrode vacuum arc remelting.

Non-metallic inclusions less than 50μm are presently impossible to be removed during typical liquid metal processing operations, even though their presence can have a negative impact on the properties of final products. The major purposes of injecting gas and generating microbubbles within a liquid metal bath include superior intermixing of reactants, enhancement of mass transfer or chemical reaction rates, as well as facilitating the removal of deleterious inclusions. Previous studies have shown that ~500μm bubbles are required to float out sub-50μm diameter particles/inclusions in tundish-type scenarios. Our current work demonstrates that microbubbles having a size range of around 500μm can be generated in a novel experimental apparatus using high-speed rotational shear at very low gas flow rates. Additionally, a new LiMCA (liquid metal cleanliness analyzer) setup was used to measure the sizes of microbubbles generated in low melting point alloys, for different rotational speeds and injected gas flow rates. The successful detection and measurement of bubbles using the new setup proved that the theory behind LiMCA can be used for microbubble/inclusion monitoring in various liquid melts.

This research investigates the potential of magnesium-zinc-calcium (Mg-Zn-Ca) alloys for use in both thermal and biomedical applications. With a density of 2/3 that of aluminum and 1/5 that of copper, magnesium and its alloys offer an attractive alternative for heat generating and electrical components in electronic devices. Additionally, the biocompatibility of Mg-Zn-Ca alloys make them a suitable material for use in bone replacement applications. The alloys were prepared by melting Mg with Zn and Ca to create different Mg-Zn-Ca alloys with varying compositions of Zn (1–4 wt.%) and Ca (0.25–0.75 wt.%). The microstructure and morphology of phases of the alloys were observed using electron microscopy. The microstructure of the Mg-Zn-Ca alloys consisted of the α-Mg matrix as well as Ca2Mg6Zn3 intermetallic phases. The Mg-4Zn-0.75Ca alloy had an electrical conductivity of 30.4%IACS (percent International Annealed Copper Standard), slightly lower than pure Mg (38.8%IACS). The lowest electrical conductivity was with Mg-9Al-1Zn at 12%IACS. Further research is required to assess the corrosion susceptibility of the alloys and their mechanical properties.

The horizontal single belt casting (HSBC) process has proven itself to be a viable casting process for strip casting of a wide range of metallic alloys, e.g., commercial aluminum alloys, advanced high strength steels, copper alloys, as well as some bulk metallic glasses (BMGs). The HSBC process offers advantages vs conventional strip casting processes including promising productivity, low energy consumption, low capital cost, low operating costs, and reduced GHG emissions. Its thinner sections of strip product and uniform higher cooling rates, plus horizontal product delivery, make the HSBC process an ideal candidate for casting BMG products. In the current study, we used three potentially vitrifiable calcium alloys (60Ca-20Mg-20Al, 60Ca-15Mg-10Al-15Zn and 55Ca-15Mg-10Al-15Zn-5Cu, %at), which were cast into thin strips. The purpose of this research work was to explore the optimal casting parameters such as maximum thickness of the bulk amorphous strips that could be cast via HSBC, based on information regarding the alloy’s glass forming temperature, its critical cooling rate, and other relevant properties. The computational fluid dynamics software ANSYS-Fluent version 19.0 was used to study an ideal metal feeding system, plus the effect of belt material and casting speed, and surface roughness, on cooling rates. The optimal combination of parameters needed to obtain completely amorphous matrix sheets were obtained for the above BMG alloy systems, showing promising results for the casting of Ca-based BMGs via the HSBC process.

Modern transportation applications, including aerospace, hybrid, and electrical vehicles, require improved lightweighting [1]. The improved lightweighting increases the mechanical and thermal loading that the castings experience [1]. Aluminum alloys are well suited to these applications due to their notable castability, high electrical and thermal conductivity, and potential for strength [2]. About 90% of commercial Al casting alloys rely upon Si and Mg alloying additions to ensure castability and strength [3, 4]. Unfortunately, the use of Si and Mg greatly reduce the electrical conductivity of the alloy [5, 6]. For example, the Al-Si high pressure die casting alloy has a low thermal conductivity of 100 W/mK [7]. This reinforcing the need for a new alloying system with high castability and conductivity.

Welding of aluminum alloys is a crucial manufacturing process to assemble and integrate the parts and components in transportation industry and aerospace sector. The commercial 4xxx filler wires provide aluminum joints with relatively low strength. To improve the strength of aluminum joints, it is required to develop new welding filler wires. In this study, the impact of Mg addition (0.6% and 1%) on the performance and strength of aluminum joints was investigated. Two commercial 4xxx filler alloys (ER4043 and ER4943) were also selected for comparison. The gas metal arc welding was used to weld the AA6061-T6 thin sheets (2 mm). The microstructureMicrostructure was studied by optical, scanning, and transmission electron microscopies. The mechanical properties were characterized by microhardness and tensile tests. The results show that the microstructureMicrostructure of all joints consists of α-Al, eutectic Si, and Fe intermetallics. The novel fillers exhibited higher number density of finer β″-MgSi precipitatesPrecipitates in the fusion zone relative to the commercial fillers. The microhardness and tensile strength of the samples joined by new developed fillers were significantly improved compared to that of the commercial fillers, in particular in the post-weld-heat-treatment condition. The new developed fillers were further used to weld high-strength AA6011-T6 thick plates (6 mm) to confirm the observed results, and to ensure their processability and performance in various conditions.

Titanium alloys for aerospace applications are expensive and difficult to process into final components. Directed energy deposition (DED), one of the additive manufacturing (AM) technologies, offers a high deposition rate and is suitable for fabricating large metallic components. So far, a majority of review articles discuss the popular powder bed fusion (PBF) with the emphasis on the “workhorse” titanium alloy – Ti-6Al-4V. There are few review articles on the DED process of a broad range of titanium alloys – near-α, β, and other α + β alloys beyond Ti-6Al-4V. This chapter focuses on the processing-microstructure-property relationships in the DED-processed titanium alloys (Ti-6Al-4V and beyond) with following aspects: (1) microstructure evolution induced by solidification, thermal cycles, post-processing heat treatment, respectively, (2) tensile properties of as-deposited and heat-treated titanium alloys, (3) defects, residual stresses, and fatigue properties, and (4) micro/nanomechanical properties of DED-produced titanium alloys. The chapter concludes with perspectives about future directions in this field.

Rare earth (RE) element mining is typically done to extract neodymium, praseodymium, dysprosium, and samarium. These RE elements are considered high-value application materials because they are in great demand for producing high-performance magnets [1–3]. These high-performance magnets are used in electric vehicles and wind turbines. However, during RE mining, these high-value elements only account for ~25% of the total extracted material [4]. The most significant by-product from RE mining is cerium (Ce), which makes up 38% of the total material and is regarded as low value [5].

The Al-Fe-based eutectic alloy featuring Zn and Mg as precipitation strengtheners was used to manufacture test plates using high-vacuum high-pressure die casting (HVHPDC). The castings have previously exhibited natural ageing with mechanical properties rising to meet up with the industry benchmark within 3 days of natural ageing in the as-cast condition. Attempting to mimic the industrial process to which some of this alloy will be deployed, some samples were given “paint bake” treatment which is typical on a coating line where the structural parts are heated to 120–200 °C for 30 minutes. The samples were treated at various ages and results obtained. It was deductible that samples of different ages react in different ways to the “paint bake” treatment. Generally, the strength of the samples would decrease upon treatment and then increase to equalize with the values of the non-paint-baked samples. However, there were different strengthening rates; some remained “dead” in the low mechanical properties state or rising very slowly to catch up with the natural ageing curve for the duration of the experiment. Samples treated at stages when the precipitates are very actively clustering or dissolving showed the worst results suggesting that it may not be a good time to disrupt the NA process.

The effect of pre-brazing deformation on the simulated brazing performance of a novel clad automotive brazing sheet is investigated including the liquid–solid interactions and microstructural changes that occur in the core alloy grain structure (i.e., recoveryRecovery and recrystallization). Differential scanning calorimetry (DSC) is used to simulate brazing of these novel sheets, and the ratio of clad solidification energy (ΔHsol) to the initial clad melting energyEnergy (ΔHmelt) is used as a metric of predicting brazing performance. Previous work has considered DSC brazing simulation as a means to assess the performance of Al sheets (Benoit et al., Metall Mater Trans A Phys Metall Mater Sci 47:4425–4436, 2016; Jin, Metall Mater Trans A Phys Metall Mater Sci 52:1409–1426, 2021; Benoit et al., J Mater Process Technol 281, 2020; Benoit et al., Metall Mater Trans A Phys Metall Mater Sci 48:4645–4654, 2017; Benoit et al., Metall Mater Trans B Process Metall Mater Process Sci 47:3501–3510, 2016). This ratio is found to increase with increasing strain from 0.43 at 0% strain to a maximum of 0.60 at 6% strain. Clad brazing sheets used in the production of automotive heat exchangers typically consist of a 4xxx (Al-Si) clad alloy and a 3xxx (Al-Mn) core alloy. During brazing of these sheets, the clad melts to provide the necessary filler metal for joining, while the core remains solid. Deformation during assembly of the heat exchangers can adversely impact the brazeability of these sheets, by increasing silicon (Si) diffusion into the core, and potentially induce a phenomenon known as liquid-film migration (LFM). In an effort to mitigate the adverse effects of increased Si diffusion and strain-induced LFM, a novel braze sheet was designed incorporating a thermal barrier layer between the clad and core alloy. The effects of incorporating such a layer on the microstructure and mechanical properties are investigated in comparison with a typical industry standard grade control sheet with no barrier layer. The current work studies O-tempered versions of these brazing sheets and observes the effects of varying pre-brazing deformation on the simulated braze performance of these sheets.

The localized corrosion susceptibility of secondary AlSi10MnMg-T7 alloys, produced using vacuum assisted high pressure die casting with different end-of-life material contents, in NaCl (aq) was determined relative to the primary alloy. Microstructure features such as grain size, Si eutectic phase and intermetallic particles distribution differed from the primary alloy, which adversely affected the localized corrosion susceptibility. Increased susceptibility is linked more so to initiation events, rather the propagation. problematic microstructure features are discussed within this context.

The objective of this work is to determine the corrosion susceptibility of Mg alloy ZAEM 1100 extruded beam profiles in NaCl (aq). Cross-section examination of the microstructure using microscopy techniques revealed three metallurgical zones: (i) a very thin altered surface zone produced from die friction, (ii) a recrystallized coarse-grained intermediate zone and (iii) a fibrous fine-grained core. The relative corrosion susceptibility of these three zones as the starting surface was investigated using potentiodynamic polarization measurements in 0.1 M NaCl (aq). The results were analyzed and interpreted by considering the role played by microstructure features.

In comparison with mainstream Al-Si alloys for structural die-casting components for automotive applications, Nemalloy HE700 (Al-Fe(Zn,Mg)) offers higher strength-to-weight ratio and elongation even without heat treatment. It is a newly developed Al-Fe hypoeutectic-based alloy with Zn and Mg additions serving as precipitation strengtheners. This study aims to determine the effect of Zn content on the microstructure and attendant mechanical properties of HE700. Alloy variations were casted as plates with three different thicknesses using high-vacuum high-pressure die casting with four different weight percentages (5%, 6.25%, 7.5%, and 8.75%) of Zn and a fixed weight percentage of Mg (1%). Mechanical properties were determined using uniaxial tensile measurements as a function of natural ageing time out to 14 days. It is observed that as zinc content increases, the electrical conductivity increases and hardness decreases. Alloy with 6.25% Zn showed better elongation (13.5%) compared to the other alloys at the end of 14 days of natural ageing but Alloy with 8.75% Zn shows better yield strength (218 MPa).

In this study, the effect of solidification characteristics during layer-by-layer material deposition of an AlSi10Mg alloy through the height of a build is discussed. To characterize the microstructural features, transmission electron microscopy was employed. Of particular interest, a bar with 4 cm height, 2 cm width, and 1 cm thickness was additively manufactured through the laser powder bed fusion technique. Two samples were extracted from the bar, one close to the bottom and the other adjacent to the top of the sample. Comparing the two samples showed that the sample taken far away from the build plate revealed remarkable differences in size and morphology of the intermetallics and subgrains. This manifests a change in mechanical behavior moving from the bottom to the top of the build.

With increasing environmental concerns and strict government regulation, the market share of battery-powered electric vehicles (BEV) in the automotive industry has increased considerably in the past decade. To keep growing their market, it is essential for the automotive industry to develop inexpensive, lightweight, highly efficient induction motors, since the average weight of the BEVs is significantly greater than that of the gasoline-powered vehicles (GPVs) [1]. As a key component in the induction motor, rotor bars need to be equipped with both high electrical conductivity and strength, because they play an important role in the field of electromechanical energy conversion and suffer from mechanical loading during service [2]. As a light metal, currently, pure aluminum (Al) replacing copper is employed for rotor bar production. However, the tensile strength of pure Al, such as the yield strength (YS) (10 MPa) and ultimate tensile strength (UTS) (45 MPa), is very low, despite its high electrical conductivity (60% IACS). To ensure the engineering performance of pure Al rotor bars, a large cooling system is installed in the induction motor, which increases the size and weight of the electric motor considerably, and consequently the weight of the BEV [3]. To lower battery energy consumption for the same range, the BEV weight must be reduced. The implementation of high-strength Al alloys for the rotor bar can eliminate the large cooling system in the motor [4]. But, the introduction of traditional alloying elements such Si, Mg, and Cu adversely affects the electrical conductivity of these alloys [5–7]. Due to the physical nature of their microstructure characteristics, the high strength and high electrical conductivity are mutually exclusive in general metals and alloys. It was pointed out [4] that, in Al alloys, insoluble alloying elements are preferred to achieve high electrical conductivity, rather than soluble elements in high-strength alloys. Fe has appeared as an attractive alloying element, since its solubility in Al is as low as 0.0052 wt.% at room temperature [4].

The demand of battery-grade graphite is rising significantly. Electrothermal purification is one of the ways to achieve 99.9+% purity of graphite flakes with minimal environmental burden. In this work, we present impurity analyses of graphite samples subjected to high-temperature treatment in an argon atmosphere (2500 °C and 2800 °C) and compare results to values reported in literature. Furthermore, as an understanding of electrical resistivity with commercial graphite flakes is still one of the key knowledge gaps in electrothermal purification technology, in this work both 2-probe and 4-probe methods are used to measure resistivity of three different graphite flakes (i.e., jumbo, large, and medium). It is observed that overall fixed-bed resistivity is dependent on various parameters such as (a) particle size, (b) void fraction, (c) interparticle contact resistance, (d) electrode to particle contact resistance, and (e) particle orientation in a fixed bed. For instance, smaller particles have higher fixed-bed resistivity. A mechanistic model for graphite flakes was developed to predict fixed-bed resistivity.© His Majesty the King in Right of Canada, as represented by the Minister of Natural Resources, 2023.

The industrial application of novel high-entropy alloys (HEAs), consisting of five or more principal elements having composition between 5 and 35 at.%, requires suitable manufacturing processes. The conventional fabrication routes for HEAs are casting and powder metallurgy. The casting route often leads to elemental segregation, whereas the powder metallurgy consumes more resources and can lead to metastable products. Additive manufacturing or 3D-printing has emerged to be effective in curbing some drawbacks of conventional manufacturing routes for HEAs [1]. The CrMnFeCoNi HEA (also referred to as Cantor alloy) has been reported to exhibit an excellent combination of strength and ductility [2]. Lately, the CrMnFeCoNi HEA fabricated via 3D-printing has been observed to have a chemically more homogeneous single face-centered cubic (FCC) solid solution structure [3, 4]. However, the selective laser-melted CrMnFeCoNi HEA has a hierarchical microstructure composed of large columnar grains, melt pools, and small cells [4]. While several researchers have studied the as-fabricated microstructures of the 3D-printed Cantor alloy, relatively scarce information is available on its deformed microstructure. Thus, this study was aimed to investigate the tensile deformation microstructure of the selective laser-melted CrMnFeCoNi HEA through electron backscatter diffraction (EBSD).

Natural and synthetic graphites are used as battery material in many applications. Natural graphite can form in the earth’s crust at about 750 °C and 5000 Bar pressure, but very slowly (requiring millions of years). As the natural carbonaceous material (mostly plant fossils) which has been available to mother nature varies in physical and chemical properties, the mined natural graphites around the world have a wide range of characteristics. The natural impurities present at each mine site typically require multiple beneficiation steps to yield a salable natural graphite concentrate (80–90% purity) which then requires purification to achieve the battery material quality (~99.9% carbon content with minimum metallic impurities). In comparison, synthetic graphite can be produced from purer feedstock (typically petroleum-based) but requires a high temperature (~3000 °C) for the graphitization reactions to be completed within a reasonable time frame (days). Currently, the battery industry consumes a mix of natural and synthetic graphites; therefore, it is important to understand their respective production routes, competitive advantages, and limitations.

Clean transportation and green energy are important components of Canada’s plan to achieve net-zero emissions by 2050, and so the applications of these technologies are on the rise. NdFeB hard magnets are central components for a variety of green energy applications such as in electric vehicles, wind turbines, and transformers, as such they are pivotal for the development of a clean economy. With that comes the growing demand for rare-earth elements (REE) containing permanent magnets which are widely implemented in electrification.

In automotive assembly, laser brazing (LB) is important for enabling high-precision, lightweight car body design with numerous fine details in body-in-white components [1]. To ensure the production of defect-free LB seams, there are automated nondestructive examination (NDE) techniques for real-time inspection. Interpreting real-time NDE data using artificial intelligence (AI)-powered processing systems represents a major step toward zero-defect manufacturing [2]. Using AI as a basis for quality control inspection enables replacing human decisions, allowing for quick correction of process conditions. Also, minimizing human interaction at production lines will boost efficiency in time, accuracy, and human recourse. As input/training dataset(s) are necessary to feed machine learning algorithms for AI development, the present work targeted emulating, on a laboratory scale, a broad variety of braze seam geometries and internal defects in LB joints that can occur in a manufacturing line. The main focus of the present study was to optimize the braze seam geometry and investigate conditions that manifest the braze seam imperfections, including a wavy appearance LB seam, spatter formation around the seam edge, and porosity, as important LB defects (key problem indicators). The formation of these defects will be understood with respect to variations in the process parameters, including laser power (LP), travel speed (TS), and wire feed speed (WFS).

High-strength, precipitation-hardened aluminum alloys, such as 7xxx series, have been intensely developed for use in the structural components of vehicles to meet lightweighting requirements. These heat-treatable alloys possess poor room temperature formability and are prone to stress corrosion cracking (SCC) in their peak-strength, T6, temper. Die quenching, warm forming, and intermediate quench and form processing routes have been suggested to improve formability of these sheets; however, their SCC susceptibility in these conditions has not been ascertained. The overall objective of the present research is to determine the SCC resistance of warm-formed peak-aged and pre-aged AA7075 alloys, but the results presented here are for the T6 temper—the most susceptible temper—to provide a basis for evaluation of the other tempers. This work employed a four-point bend test setup following the ASTM G39 standard procedure and was compared to direct tension test in ASTM G49. Unlike samples under direct tensile in ASTM G49, the stress variation between 70% and 90% of yield strength applied on samples exposed to 3.5% NaCl content did not cause cracking after 40 days under bend test, despite testing the most susceptible temper to SCC, i.e., T6 temper. However, when the chloride amount was tripled on day 41, and monitored until days 120–150, through-thickness corrosion cracking was observed on these specimens and SCC severity increased with stress level.

The demand for high-capacity batteries is accelerating as the world seeks to decarbonize industrial sectors. The anode in these batteries typically contains a significant quantity of high-purity graphite, which is mostly produced in Asia using hydrometallurgical processes. Canadian manufacturers are alternatively exploring pyrometallurgical processes that can directly use electrical heating, which can be from renewable energy. An option is to use in situ electrodes in a fluidized bed reactor to provide direct resistance heating of the graphite particles to the required temperatures (up to 3000 °C). As this is a developing technology, the objective of this investigation is to characterize various natural graphite flake populations and their resulting ambient-temperature fluidization behavior.

The formation of solidification cracks during fusion welding of high strength and highly alloyed wrought aluminum alloys has been a significant challenge over the years. Recently, using TiC nanoparticle-enhanced filler metals was found to be an effective way for solidification crack elimination during TIG welding of Al7075 sheets. However, the impact of welding parameters on weldability in the presence of nanoparticles is still not completely understood. Therefore, the present research investigates the weldability of 3-mm thick Al7075 sheets with TiC nanoparticle-enhanced filler metal (Al7075) during TIG welding. Two sets of welding parameters, leading to two different heat input levels, are studied. The experimental results show that the filler metal effectively eliminates solidification cracks in both joints. Microstructure evaluations show an equiaxed grain morphology in fusion zones with an average grain size of 19.6 ± 2.6 and 26.2 ± 1.5 μm for joints welded with low and high heat input, respectively. However, statistically similar microhardness values are measured on both joints, suggesting no significant impact of the grain size.

In this study, AlSi10Mg alloy wasfabricated using the laser-powder bed fusion (L-PBF) technology and then subjected to multi-pass friction stir processing (FSP) up to three passes. The microstructural evolution of the friction stir processed (FSPed) and as-built specimens were examined using scanning electron microscopy, electron backscatter diffraction analysis, and X-ray diffraction analysis. In terms of mechanical properties, the hardness of each specimen’s stir zone was measured. FSP was found to drastically alter the distribution of Si particles within the ultrafine-grained structure of Al matrix in the processed region. The impacts of multi-pass versus single pass FSP on the degree of attained microstructural homogeneity in the alloy were also explored and comprehensively elucidated.

The present study investigates the development of a biocomposite feedstock material compatible with fused filament fabrication (FFF) 3D-printing and injection molding (IM) based on polylactic acid (PLA) biopolymer and wood flour (WF) as the bio-filler, in consideration of sustainability and affordability. The effective reinforcement of biopolymer with wood flour filler, as a by-product of the forestry industry, will not only reduce the depletion of wood resources but also minimize the adverse effects of fossil fuel-based plastic production on the environment. Different formulations with wood flour concentrations up to 40 wt.% with and without polyethylene glycol (PEG) as a plasticizer were developed. The microstructural and mechanical properties of the 3D-printed and injection molded parts were analyzed to highlight the effect of production process on the properties of wood-based biocomposites. The results showed comparable tensile strength and modulus values for both 3D-printed and injection molded samples at 40 wt.% of wood and 10 wt.% of PEG, while plasticization of compound resulted in reducing the tensile strength and modulus in both 3D-printed and IM specimens. The results suggested that optimization of 3D-printing parameters through a systematic and robust experimental design is critical to obtain high-quality printed biocomposites for end-use applications in high-demand industries such as construction and automotive.

In the past decade, the emergence of high-entropy alloys (HEAs) and other high-entropy materials (HEMs) have brought about new opportunities in the development of novel materials for high-performance applications. In combining solid-solution strengthening with grain-boundary strengthening, new material systems—nanostructured or nanocrystalline (NC) HEAs or HEMs—have been developed, showing superior combined mechanical and functional properties compared to conventional alloys, HEAs, and NC-metals. This chapter reviews the processing methods, materials, mechanical properties, thermal stability, and functional properties of various nanostructured HEMs, particularly NC-HEAs. With such new nanostructures and alloy compositions, many interesting phenomena and properties of such NC-HEAs have been unveiled, for example, extraordinary microstructural and mechanical thermal stability. As more HEAs or HEMs are being developed, a new avenue of research is to be exploited. The chapter concludes with perspectives about future directions in this field.

Modern industrial gas turbines and aero-engines have to be operated at higher temperatures and pressures than their previous generations. It is a necessity not only to maintain a high-performance operation but also to meet the stringent regulations on pollutant emissions. As such, the development of an advanced cooling technology is highly required to prevent the failure of gas turbine hot gas path components like combustor liner and turbine blades [1]. Transpiration cooling is deemed as one of the most efficient cooling systems that involves injecting coolant through porous medium to create a protective layer (i.e., film) of coolant over the surfaces of components and keep their temperatures low, thereby preventing them from becoming overheated and degraded over time. Porous medium-based transpiration cooling was first introduced in the 1950s [2]. However, it could not be applied in the gas turbine industry because of the challenges associated with the design and manufacturing porous structures. Nowadays, the development of transpiration cooling in actual gas turbine applications is actively progressing thanks to the recent advances in 3D additive manufacturing, also known as 3D printing [3]. This technique enables the precise manufacturing of intricate cooling channel geometries and shapes with highly customized and optimized designs, such as TPMS lattice structures, which would be impossible to be produced using traditional manufacturing methods [4]. Regarding the film cooling of gas turbine components, while there are numerous studies on the discrete-hole effusion cooling concept, porous medium-based transpiration, cooling has rarely been investigated. Therefore, the objective of this study is to optimize the adiabatic film cooling effectiveness of transpiration cooling according to the types and porosities of TPMS structures (see, Fig. 1) through an experimental case study.

Hatch Smelter Production Digital Twin offers a comprehensive, cloud-based solution that optimizes smelter production planning and scheduling. It assists operators in achieving their desired throughput targets by encompassing multiple stages of the smelting process, from furnace to downstream converter operations. The solution takes into account capacity, logistical, and environmental constraints, as well as specific quality and process requirements, allowing for the simultaneous coordination of various activities and material flows across the smelter and converter aisle. This solution is applicable for different smelting processes such as nickel, copper or platinum group metals (PGM).

With rapid development of biomedical engineering, the fabrication of multifunctional biomedical device with the joining of dissimilar materials is drawing researchers’ interest [1]. Stainless steel (SS) and Pt are both widely used materials in micro-scale biomedical device due to their good mechanical properties and biocompatibility [2, 3]. The micro-joining between SS and Pt to combine their advantages is in high demand; however, few efforts have been made on this topic.

The effect of non-isothermal aging on the mechanical properties and corrosion resistance of Al-9Zn-2.3Mg-1.9Cu (AA7056) alloys were investigated. The results revealed that thick materials were limited to retrogression and re-aging treatment (RRA). It could not reach the retrogression temperature in the RRA treatment. Compared with the RRA treatment, the non-isothermal aging (NIA) treatment produced discontinuous precipitates at grain boundaries, while the intragranular precipitates were fine and dense. The strength was similar to that of the RRA treatment; the corrosion resistance of the alloy was significantly improved by NIA aging. NIA treatment was less affected by the thickness of the alloy. The difference between the actual temperature and the setting temperature of the alloy is minimal during the aging process. The combination of properties could overcome the fact that RRA treatment cannot handle thick materials.

Rare-earth (RE) permanent magnets have found a wide range of applications in electronic components such as laptops, speakers, and hard drives as well as electric products like hybrid and electric vehicles and wind turbines [1, 2]. As such, the production of permanent magnets via advanced manufacturing techniques, including metal additive manufacturing (metal AM), injection molding, and spark plasma sintering, among others, has been the topic of research and development in the past couple of decades [3, 4]. It is well known that the feedstock powder for these manufacturing techniques shall meet strict chemical and morphological specifications, including particle sphericity. Sadly, one of the most common RE magnets, NdFeB, is produced as powder by strip casting and jet milling or by hydrogen decrepitation process, both of which yield irregular/angular powders. Such irregular powders exhibit low flowability making them unfit for most advanced manufacturing techniques. This work presents the use of an induction plasma system to spheroidize irregular NdFeB powders. The effect of plasma conditions on the sphericity of the powder is discussed. It is shown that highly spherical powder can be obtained at an optimum plasma condition. Crystalline structure and apparent density of NdFeB powder, prior to and post-plasma treatment, are obtained and compared.

The high-entropy alloys (HEAs) are a new type of materials that contain at least five principal elements [1], and the most common combinations are 3d transition metal HEAs with bases such as AlCrFeNi and CrFeCoNi [2]. These HEAs have high fracture toughness [3], yield strength, and specific strength compared to conventional alloys [4]. Research into coatings is also in constant need of innovation, as the surface of the workpiece is in direct contact with the outside environment and its surface properties determine the service life of the workpiece. To further improve the properties and application areas for current engineering alloys, new coating designs and processes are needed. Among different coating techniques, a micro-welding technique known as electro-spark deposition (ESD) has the ability to coat any conductive materials onto workpieces with a low cost. The ESD process makes use of a consumable electrode to deposit material on a conductive substrate through the creation of a momentary short circuit. The momentary nature of the electric arcing and the small area impacted on the substrate results in very little heat transfer to the substrate. The minimized heat-affected zone and the formation of true metallurgical bonding between the deposited material and substrate make ESD an attractive option for coating deposition on engineering alloys. The coatablity of HEAs using ESD, however, still lacks understanding.

The effect of the hot top geometry variations on the solidification time and macrosegregation formation during the solidification of a 12MT cast ingot made of a Cr-Mo-low alloy steel was investigated. The bottom pouring ingot casting of a 12 MT cast ingot was simulated by the three-dimensional finite element modeling code THERCAST®. The accuracy of the model was validated by experimental results of the macrosegregation map of a real ingot. The influence of the hot top geometry including an increase and a decrease in hot top height on the solidification parameters was determined. The results showed an increase of 27.5% and a decrease of 5% in the solidification time by an increase of 165mm and a decrease of 200mm in hot top height respectively. The new hot top geometries revealed variations in the range of macrosegregation (comprising the maximum and minimum values of macrosegregation) in different locations of the ingot.

Binder jetting additive manufacturing (BJAM) has a unique advantage in mass production of steel owing to its high productivity and scalability. Powders used for BJAM can be further explored toward the adoption of low-cost material systems to enable industrialization in high-volume markets. This provides a use case for water-atomized (WA) AISI 4340 steel, which offers comparatively good mechanical properties while reducing raw material cost. This work compared densification, sintering anisotropy, and geometrical deformation in BJAM WA 4340 parts with gas-atomized (GA) counterparts during sintering in an optical dilatometer. Dilatometry results were then processed using a master sintering curve (MSC) approach, allowing for further comparison. The results showed that the BJAM WA 4340 components can attain final densities comparable to the GA counterparts via supersolidus liquid-phase sintering (SLPS) while maintaining geometrical fidelity. This trend will be further validated on BJAM parts with more complex geometries.

17-4 precipitation hardenable (PH) stainless steel is a commonly used alloy for a wide range of industrial applications, making it a valuable addition to the additive manufacturing (AM) sphere. In order to confidently use 17-4PH as an AM feedstock, its behavior must be understood under the wide range of thermal conditions and rapid solidification rates characteristic of AM processes. There have been many studies on the microstructure and properties of 17-4PH in laser powder bed applications, but most focus only on final heat-treated microstructure with little attention paid to the as-built microstructure [1–4]. There is very little published research on the microstructure of 17-4PH using plasma-based additive manufacturing methods. Clearly, a large gap still exists in the understanding of 17-4PH that must be addressed before AM parts built with 17-4PH can be used. This work begins to address this gap by observing the relationship between the microstructure, the thermal gradient, and the velocity of the solidification front to build the foundation for a process–structure–property relationship for this alloy.

This chapter reviews common laboratory toughness test methods to characterize hydrogen embrittlement effects, presents representative results, and comments on limitations of the methods. Fracture resistance properties appear to be vital for the safety of higher material utilization in hydrogen pipelines (i.e., high-design stresses per ASME B31.12 Option B); however, further developments of the existing test methods and standards are needed. This paper can serve as a discussion piece at the symposium of advanced manufacturing and materials to further develop materials qualification tests for the design of pipelines transporting pure hydrogen and hydrogen blends.

This work explores the rapid solidification of hypereutectic Al-40 wt.% Si alloys with and without Ce addition to attain modification of primary Si. Al-40Si and Al-40Si-1.5Ce powders were produced by impulse atomization with liquid cooling rates ranging from ~103 to ~105 K. The microstructures of both alloys showed an Al-rich halo surrounding the primary Si-phase. This was not part of the predicted Gulliver-Scheil solidification paths. The presence of this structure suggests solidification of both alloys deviated from local equilibrium. In both alloys, increasing cooling rate was associated with the formation of less elongated primary Si presenting a more rounded surface. Additionally, alloying with Ce improved the distribution of primary Si in the microstructures of the smallest powders. Quantitatively, the microstructures of both alloys were found to increase in primary Si and halo content as cooling rate increased. The use of Ce also led to a measurable decrease in eutectic content in Al-40Si-1.5Ce with respect to the unmodified alloy. Similarly, primary Si and halo volume percent also increased as a result of Ce addition. Ce addition led to the formation of finely dispersed intermetallics within the eutectic structure. While four different intermetallics are predicted by the Gulliver-Scheil solidification path of Al-40Si-1.5Ce, only AlCeSi and possibly CeSi were identified. Rapid solidification thus suppresses the formation of some intermetallics.

The most popular marine industry alloy of nickel-aluminum bronze (Cu-9Al-4Ni-4Fe-1Mn) was considered for additive manufacturing (AM) via the selective laser melting (SLM) procedure. Non-equilibrium precipitation of the κ-phases upon rapid cooling with the SLM technique was studied using advanced characterization techniques by scanning transmission electron microscopy (STEM) and atom probe tomography (APT). These structural investigations revealed the occurrence of martensitic phase transformation with the super-saturation of elements through the lattice structure upon rapid solidification. Also, the APT analysis interestingly displayed a high fraction of nano-scale Fe-rich clusters inside the martensitic laths in the form of κIV precipitates. Based on the evident microstructural features, the results of the present work establishes the occurrence of the κIV as a non-equilibrium phase with a high probability of formation during rapid cooling in SLM processing in addition to the martensitic phase transformation.

Lithium is a critical element for energy transition, especially in battery manufacturing. Canada is hosting large reserves of lithium as brines and pegmatite hard rocks and has a great potential to be a major lithium producer. The hard nature of the pegmatite ore body, as compared to lithium extracted from brines, is an important reason for the limited development. With a growing global demand related to clean technologies, one Canada’s strategy is to give a priority to the lithium supply chain. Spodumene in pegmatites occurs as large minerals intermixed essentially with quartz, feldspars, micas. This petrological feature made it a suitable feed for efficient and selective liberation of spodumene by high-voltage electric pulse (HVEP) fragmentation. Using HVEP fragmentation, individual coarse minerals of the ore are much better liberated than in the case of conventional grinding techniques. In the current study, the HVEP technology is compared to jaw and cone crushers (conventional) for effective size reduction prior to dense media separation (DMS) of spodumene in a pegmatite ore. The results showed that HVEP fragmentation allowed to almost double the DMS recovery of spodumene, improving from 7.1% Li2O by conventional crusher to 14.1% Li2O (relative to feed). This preliminary study suggests opportunities for more sustainable spodumene mining and extraction approaches, specifically well adapted to some Canadian mineralized zones, especially if these are far from mineral processing plants.

Ore deposits are complex and display a high degree of variability which impact their beneficiation. Automated mineralogy (AMIN), which includes ore characterization, mineral and textural quantification, grain size, and mineral liberation in relation to the grinding and beneficiation, is an integral part of the mineral processing industry for the understanding of critical minerals, and base metal sulfides, etc. The data obtained from AMIN can be linked to metallurgical response and used to guide and explain test results, which can help in flowsheet development, process design, and optimization.This study provides a case study on a lithium ore sample from Quebec, Canada. Mineralogically limited (predicted) grades and recoveries were used as a proxy for beneficiation (e.g., flotation) characterization. Through laboratory testwork, the sample, categorized by size fractions, the correlation between mineralogy and mineral recovery concerning modal mineralogy, grain size, and liberation properties were demonstrated.For this sample, spodumene was >80% liberated at −300/+150 μm (micrometers) and −150/+75 μm grain size fractions. The flotation recoveries of lithium at 80% passing 205 μm (100% passing 300 μm) and 80% passing 135 μm (100% passing 180 μm) were not significantly different (confirmed with t-test). The mineralogical data indicate that there is potential to improve the recovery and grades of lithium with flotation.

Flotation is the most used separation process worldwide. Flotation characterization is usually carried out in batch conditions at laboratory scale. A dynamic phenomenological description of the flotation process is challenging. However, flotation performance evaluation by means of the utilization of a pilot plant is beneficial to reduce uncertainty on metallurgical results. In addition, leveraging pilot plant results by digitizing them helps describe the process dynamically. Consequently, flotation pilot plant testing allows a digital twin (DT) to be generated by combining ore characteristics, process information, and a digital architectural platform. Therefore, the generation of a Digital Twin of a flotation pilot plant provides a tool to explore and evaluate new operating scenarios. This permits the identification and scale up of an optimum scenario (i.e., industrial operation). In other words, the pilot plant with its digital twin may become the physical twin of the industrial plant as long as a robust scale-up methodology is available. This contribution proposes an innovative and advanced geometallurgical characterization to evaluate ore variability and its metallurgical performance holistically. It is believed that this new proposed approach will help plant operators improve their technical and economic performance.

The surging worldwide demand for rare earth elements (REEs) and uncertainties in the global REE supply chain motivated the development of several processing flowsheets for Canadian REE deposits. The Canadian Critical Minerals Strategy is essentially an industrialization plan for a net-zero economy that strives to ensure a domestic source of critical minerals and establish sectors like the production of electric car batteries. In this study, a best laboratory practice is used to add predictability to the Ashram Project located in northern Québec, Canada. The objective of this research project was to produce a bench-scale REE concentrate with high recovery and acceptable grade, and a high-grade concentrate with acceptable recovery while keeping reagent consumption low. The study aims to investigate the effect of different parameters, such as the grinding size and flotation reagent schemes on the beneficiation performance, and to optimize the process conditions for maximizing the REE recovery and grade while minimizing the REE losses to the tailings, all of this while considering the challenge of fine grinding required to liberate the REE minerals. Process mineralogy and beneficiation techniques such as heavy liquid separation and flotation were used.

The Cantung mine is a formerly operating tungsten mine located in western Northwest Territories. As part of the Northern Abandoned Mine Reclamation Program, the Canadian government is looking to remediate the property. This may include reprocessing the tailings to isolate potentially acid-generating sulphide minerals, mitigating any possible environmental liability to the nearby Flat River and its confluences. Cantung’s mineral processing operations produced three concentrates and one tailings product: a high-grade WO3 concentrate; medium grade WO3 concentrate; a copper concentrate; and sulphidic tailings. During periods of low copper prices, chalcopyrite was not recovered from the ore and was instead directed to tailings. Poor recovery from the scheelite gravity separation circuit combined with intermittent chalcopyrite flotation resulted in the tailings containing notable quantities of copper and tungsten, which could potentially be recovered during reprocessing to offset costs. Experimental work was completed on tailings samples collected from tailings pond #3, Cantung’s largest tailings impoundment. Ideal flotation conditions were determined to remove potential acid-generating minerals (mainly pyrrhotite) while also recovering residual valuable minerals, primarily chalcopyrite. A polish grind of the tailings sample prior to flotation was found to increase sulphide mineral recovery. Up to 86% of sulphur and 84% of copper were concentrated into 30% of the sample mass using flotation, while between 80% and 95% of tungsten reported to the sulphide flotation tailings. Future work will investigate collector and dispersant dosages in a mixed xanthate-hydroxamic acid collector system using a design of experiments to optimize conditions for sulphide mineral recovery from the tailings.

A paradigm shift is underway globally in energy generation and consumption, focusing on a transition to electrification and energy sources that do not create green-house gases (GHG). This new economy will increase the demand for minerals such as copper, nickel, graphite, and lithium, among others. While the demand for these minerals is expected to increase, grades of mineral deposits and reserves are decreasing every day, and some of these deposits are located in areas of high social conflict with opaque governance structures that make mining development difficult and problematic. The search is on for innovative and more efficient ways of extracting and processing mineral resources. One of these is coarse particle flotation (CPF), which was first used at industrial scales for sulfide ores using the Eriez HydroFloat® at Newcrest’s Cadia Valley in 2018.There are two main families of CPF applications; the first being “Tail Scavenging” (TS), where the HydroFloat is used to recover an additional 3–6% of the total milled mineral and to increase the throughput for a brownfield application. The second is “Coarse Gangue Rejection” (CGR), where the HydroFloat system is inserted in the mill circuit and allows reduction in mill power, and the production of significantly coarser sized tails, typically two to three times than conventional mill tails. It is this latter application that has the potential to greatly reduce power and water consumption, as well as improve metallurgical efficiency. An industrial-scale CGR application was installed at Anglo American’s El Soldado concentrator in Chile in 2019, and a recent paper explained the design concept, operation, and benefits, largely de-risking the application for future practitioners. In this paper, some of the considerations for implementing CGR applications in world-scale concentrators of the future will be discussed including test-work and scale-up, the reduction in electrical energy, net-water consumption, and the improvement in metallurgical efficiency.

Continuous achievement of optimal flotation cell operation (maximum recovery at a given throughput rate) in a mineral processing facility is extremely challenging. Operators must coordinate air flow, reagent addition, and pull rates in response to both gradual and sudden changes in feed rates and composition. Moreover, they must do so using limited measurement technology that leaves uncertainty about incoming and outgoing composition and flow rates. However, suboptimal flotation operation resulting in even fractions of a percentage in recovery losses have significant impacts on site-wide economics, and can cost even small–medium producers millions of dollars per year in lost revenue.Over the past two decades, many model-based advanced control strategies have been proposed and developed to address this pressing problem, but many operations have struggled to achieve meaningful sustainable results in real production environments. In this paper, a novel field-tested method for controlling and continuously optimizing flotation operation will be presented. Key features of this solution include: Novel measurement of open-channel flotation pull rates using conventional, accurate, and robust measurement technology. A novel, flexible approach to control of a single bank using a technology known as Integrated Quadratic Control (IQC) that allows metallurgists and operators to guide automation in order to provide optimal coordinated operation that remains stable, even through major upsets to feed supply and grinding operations. A novel approach to site-wide recovery maximization that coordinates flotation from roughers to cleaners, balancing pull rates against final assay-grade requirements. Contents of this paper include an overview of the above methodology along with performance results in both pilot scale and full-scale production environments.

Improvement in energy efficiency, productivity, and recovery of minerals during mineral processing can help in economic savings and meeting the requirements of high-demand elements. Microwave pretreatment of ores has shown some potential benefits in these aspects. This research aims to study the impacts of microwave treatment on kimberlite ore as a major source of diamonds. Kimberlite samples were treated in a single mode microwave cavity with different powers and exposure times and then crushed using a single roll crusher. The crushed product was first separated by densiometric testing and then screened into different size fractions. The results show that microwave treatment leads to a reduction in specific crushing energy as well as a bigger concentrate fraction with respect to better liberation after single crushing attempt. This study emphasizes the potential application of microwave treatment on the kimberlite ore for better separation of dense minerals as well as improving energy efficiency during comminution.

This work describes the flotation results of sulphide gold-bearing minerals in two samples of a refractory gold ore from a deposit located at Minas Gerais State in Brazil. The flotation performance was evaluated at bench and pilot scale (Eriez). For both samples, the P80 was 75 μm and the activator dosage, collector and frother type, and dosage and circuit configuration were evaluated. The feed sample for the bench studies analyzed 7.8 g/t Au and 3.4% S and 5.2 g/t Au (gold) and 2.8% S (sulphur) for the mini pilot plant. The results obtained for the rougher stage at bench scale showed that it is possible to obtain concentrate grades of 23 g/t Au and 11% S with Au and S recoveries of 90% and 94%, respectively. For the mini pilot plant tests (rougher), the results were 17 g/t of Au and 9% of S grade with Au and S recoveries of 93% and when applied at rougher and cleaner stages, concentrate grades with 27 g/t of Au and 13% of S grade with recoveries of Au and S of 91% were obtained. Data obtained are discussed in terms of physicochemical properties related to the reagent’s combination and hydrodynamic parameters at the mechanical cells.

This extended abstract provides an overview of the Methods to Survey and Sample Grinding Circuits for Determining Energy Efficiency guideline published by the Global Mining Guidelines Group in 2023. The guideline aims to provide tools for practitioners to measure the energy efficiency of comminution circuits using standardized metrics. The guideline details methods to survey and sample grinding circuits to generate sufficient information of suitable quality to support reliable efficiency analysis by these and comparable methods. The guideline is specific to surveying and sampling autogenous and semi-autogenous grinding and rod and ball mill circuits operating within the normal range of application.

The residence time distribution (RTD) of a chemical reactor is a probability distribution function that describes the amount of time a fluid element could spend inside the reactor [1]. The RTD is usually determined to evaluate how far removed the hydrodynamic of a real reactor is from ideality. In particular, flotation cells are nonideal reactors that present inefficiencies from the hydrodynamic perspective. In order to formally address the distribution behavior of fluid elements in flotation cells, a sequence need to be followed. Figure 1 shows a sequence for the estimation of the RTD considering the pulse injection method. This figure depicts the C–Curve, E–Curve, and F–Curve. These curves are needed to process the experimental data associated to RTD. In addition, this diagram also shows the moments of the RTD commonly used to compare different distributions.

The carbothermic reduction of copper slag with borax and charcoal was investigated in this study, followed by leaching with H2SO4 and HCl. The XRD and SEM-EDS techniques were used to characterise the copper slag sample. The HSC Chemistry software was used to compute the standard Gibbs free energy at each reaction temperature. The effects of the borax and the reduction temperature were investigated in the reduction experiments in order to identify the mechanism of enhanced reduction. The degree of metal dissolution in relation to acid concentration was investigated in the leaching experiments. According to the HSC Chemistry results, the reduction of Co and Fe metals in copper slag is an endothermic reaction, whereas the reduction of Cu is an exothermic reaction. The mineralogical analysis revealed that the primary phases in the copper slag were fayalite and magnetite. The experimental results demonstrate that carbothermic reduction can achieve high extraction efficiencies of Co, Cu, and Fe under optimal conditions of 20% borax, 10% charcoal for 90 minutes of reduction time at 850 °C and 5.4:1.8 M H2SO4/HCl concentration for 90 minutes of leaching time.

The metallurgical and cement industries account for a substantial share of anthropogenic carbon dioxide emissions. Utilizing oxidic by-product materials from the metallurgical industry as supplementary cementitious materials (SCMs) is a means to improve resource efficiency and lower the emissions from cement production. While the former effect is self-explanatory, the latter is a consequence of the partial replacement of Portland cement with the SCM, which requires neither calcination nor clinkering. The previously published literature for incorporating iron silicate slags in SCM applications includes various testing procedures with multiple parameters varying between studies. Therefore, the present paper offers a first insight into the effect of processing parameters on the inherent reactivity of an industrially produced iron silicate slag. More specifically, the effect of onset granulation temperature and time of grinding on the evolved heat in isothermal calorimetry experiments were studied. The results showed that granulation temperature had an insignificant effect on the evolved heat. Increased grinding time showed contrasting trends in the juxtaposition of evolved heat normalized against mass and surface area. The former increased with prolonged grinding, while the latter decreased. Based on the results, previously reported data were considered, highlighting the need for future studies on controlled variations in chemical composition.

One of the most significant sources of copper losses from pyrometallurgical copper extraction is attributed to dissolved and entrained copper in the discarded slag. The entrained copper can be recovered via pyrometallurgical slag cleaning in a settling furnace. Reduced copper losses mean increased smelter profits by improved raw material efficiency, and in addition, the slag will become a more environmentally safe by-product. One way to increase the copper recovery during the settling process is to modify the slag to improve the properties that decrease copper solubility and slag viscosity. In this study, iron silicate slag was modified using CaCO3 on an industrial scale to evaluate its effect on the settling process. More specifically, the changes in settling were related to the modifications and measurements of slag viscosity and copper droplet size distributions in the slag. The trial was evaluated by comparing the copper content in different batches, the size distribution of copper-containing droplets using automated scanning electron microscopy, and performing rheological studies using a high-temperature rheometer. The results showed that increasing the CaO content of the slag by modification with CaCO3 has a positive effect on the settling process and is thus a possible method to improve the industrial settling process of valuable metals in slag.

To strive towards carbon neutrality, metallurgical industries are focusing on electric furnaces. The pyrometallurgical processes typically oxidize impurities to metal oxides, which end up in the slag. One issue in pyrometallurgical processes is metal losses to the slag phase, limiting the process efficiency. To solve this, slag cleaning is required in electric furnaces, which can serve for both decantation and reduction.In electric submerged arc furnaces, thermal energy is supplied primarily by the Joule effect, which is inversely related to the slag conductivity. Hence, the electrical conductivity of the slag is essential for operating electrical furnaces. Unfortunately, it is a parameter, which is very difficult to measure and thus requires a very specific experimental set-up so that data are scarce.Moreover, increased scrap usage makes the process feed more variable so that the use of a ‘digital reactor twin’ is put forward as the solution. To make such a digital twin, also other physical slag properties (viscosities, diffusion coefficients and surface tensions) need to be known as a function of temperature, atmosphere and composition. At Ghent University, we propose the use of a combined experimental–modelling approach. Certain issues with the separate approaches are discussed in this paper and clearly showcase the usefulness of the combined approach.

Rio Tinto Kennecott Smelter took an approach to study the performance of the flash smelting furnace concentrate burner. The wear patterns of the air slide, disperser, and shifted reaction shaft temperatures indicated that the delivery of the solids and air is not uniform at the concentrate burner. The approach to improve the performance included adjusting the air delivery to the windbox, flap installation in the air slide, and modifications of the disperser. This chapter will provide an overview of the action taken and the results of improvement of the concentrate burner performance. Experiments were focused on the feed uniformity across all the quadrants of the burner. The results were used to modify disperser fins to obtain more uniform distribution of the feed to the concentrate burner.

Copper is an essential metal for growth and modernization of the world economy. It is extensively used in infrastructure, construction, transportation, and equipment manufacturing. As the quality of copper deposits across the world is depleting and the time and cost to develop new projects are increasing, the required primary supply to meet the future demand is being challenged. Although a major portion of the copper demand will still be filled by the primary smelting of concentrates, the copper recycling will play a crucial role in filling the supply gap. Furthermore, there is a significant risk of a supply crisis of critical metals, which has made the recycling of secondary resources ever more important, especially the E-Waste material. The pyrometallurgical process continues to be a dominant route for both primary and secondary production of copper. The current work explores the opportunities and challenges of E-Waste recycling via a pyrometallurgical route to recover copper and critical metals. The study includes a comparison between the modern smelting technologies to assess their flexibilities of treating the E-Waste material. In particular, the two options of E-Waste treatments have been explored: (1) injecting E-Waste directly into primary production line and (2) production of black copper followed by its refining. The current review shows that both options require a proper management of refractory oxides and equilibrium oxygen potential for economic recoveries of copper and other critical metals.

The pre-heating and pre-reduction are increasingly considered upstream of the smelting stage in the FeMn industry, both to save energy and limit the CO2 emissions. In this study, the effect of pre-treatment and ore type was investigated by 11 pilot experiments. The charges were based on four different ore kinds that were either left untreated, pre-heated in air at 700–900 °C in the absence of carbon or pre-reduced in air at 700–900 °C together with coal. During the subsequent smelting stage, widely different temperatures were observed in the furnace: This is of critical importance as the 800 °C isotherm is considered a turning point in the occurrence of the Boudouard reaction. This reaction has major consequences on the extent of CO-based reduction of manganese ores and on the overall carbon consumption and CO2 emissions. In the present work, temperature field estimates generated from measurements at specific positions inside of the charge were linked to material flow and gas composition using kinetic models developed at laboratory scale to predict the pre-reduction of the ores. Predicted and measured O/Mn ratios in the ores are then compared and used to discuss the overall reduction process in the FeMn pilots. The kinetic model was also fitted for the charges for which no kinetic data were available; new kinetic data were thus derived from the pilot experiments.

The global depletion of easily accessible primary copper reserves (from mined oxide/sulfide concentrates) has led to secondary copper processing assuming an ever-increasing importance within the worldwide copper industry. The contribution from recycled copper scrap is a significant fraction of the global copper production and is currently estimated at 29%. The main impurities found in copper scrap are lead, tin, zinc, iron, and nickel. These elements can only be removed by using both highly oxidizing conditions and the addition of fluxes with multiple refining steps. The most recently designed secondary copper reverberatory units generate significant quantities of high-temperature fluid oxidic slags, which have been found to be very corrosive to the typical magnesia–chrome refractories commonly used in primary copper processing vessels. Alumina–chrome refractories, however, have been found to be highly resistant to these refining slags and have contributed significantly to increasing the lining life in the slag line zones of these secondary refining furnaces. Furthermore, these bricks exhibit minimal penetration of slag and metal into the working surface and can be economically recovered from the used lining, crushed, and reintroduced into the feedstock used for manufacturing new brick for relining the secondary copper furnaces. This chapter discusses the potential scope for the future of scrap copper recycling in North America and the alumina–chrome refractory furnace linings required for optimal production processes. It also predicts the likelihood of recovering a high percentage of the used alumina–chrome furnace brick for reintroduction into the feedstock for new brick production.

The authors proposed a two-stage solid-state nickel extraction method that avoided the smelting of magnesium silicates in the ultramafic nickel concentrate. The mixture of the nickel concentrate and metallic iron powder was heated at 950 °C followed by slow cooling to 750 °C and over 90% of nickel was extracted from pentlandite into the ferronickel alloy phase. The alloy contained 20–30 wt% nickel and had a characteristic grain size of 40–50 μm.

Metal production technologies are quite old, and they rely on carbon-based reductants and fossil fuels. The industry has recently substituted electricity as a heating source. Finding green reductants has been a long-running endeavor, nevertheless. In place of carbon, electrons were used as alternate reductants in electrometallurgyElectrometallurgy. Electricity is used to provide both the heating and chemical reaction energy needed, making it possible to achieve the goal of net-zero metal production. Aluminum was the first metal electrochemically smelted in molten halides; since then, numerous advancements in this field have been made. To list a few, inert cathode and anode materials are being emerged to reduce the emission of toxic and greenhouse gases. Graphite is the typical anode used in high-temperatureHigh-temperature operations, which when interacted with released anodic oxygen leads to CO2 formation. In addition, novel electrochemistry has been developed to produce reactive metals such as titaniumTitanium that cannot be produced via carbothermic reductionCarbothermic reduction or electrolysis in aqueous solutions. This chapter briefly covers the recent developments aiming at sustainable extraction of various metals including Ti, Si, Cu, Ta, V, and Fe. The developed electrometallurgical technologies for recycling of valuable metals from urban and industrial waste are also discussed.

To remain competitive and sustainable, the pyrometallurgical industry has to continually innovate. The drivers of this innovation have been environmental compliance, reduction in energy and material consumption, cost reduction, and adaptation to feed materials. The industry has developed many innovations in process design, reactor design, and process control. The author has been involved in many of these developments in the last 50 years. The author developed a long-term collaboration with Dr. Bert Wasmund in this endeavor. This paper highlights some of these developments as well as others and their impact on the industry. In the future, there is going to be an increasing emphasis on decarbonization of the processes. Pathways to decarbonization are briefly discussed.

In 2011, Bert Wasmund and colleagues published an informative paper entitled “Implementing New Technologies in Metallurgical Processes: Building Plants that Work.” Wasmund reviewed the implementation path and ramp-up of new non-ferrous pyro- and hydrometallurgical technologies with a focus on successful elements that led to a rapid plant ramp-up and met stakeholder expectations. Fast forward to today, and we see that the steel industry is in the initial stages of a generational change, implementing new process technologies to reduce the greenhouse gas emissions (GHG) related to the blast furnace-BOF steelmaking route. New steel technologies propose to incorporate both elevated-temperature metallurgical and lower-temperature chemical processes in a unique fashion to achieve a significant reduction in GHG emissions.The challenges faced with new metallurgical technology and pathways that Wasmund identified for success are presented. Case studies regarding alternative ironmaking technologies including the Midrex™, Energiron™, HIsmelt™, and Finex™ processes are discussed to identify the unique elements that led to success. Key considerations to create successful outcomes for green steel technology developments are presented.

Aurubis, with its complex integrated smelter network, treats various primary and secondary raw materials originating mainly from mining and recycling to recover 19 different metals such as Cu, Au, Ag, Ni, Sn, Zn, Pb, Se and PGMs. Within these processes, intermediates are produced, which are further refined to recover pure metals or metal compounds. One of these intermediates is Cu-Pb-matte which is converted in a Top Blown Rotary Converter (TBRC) to obtain blister copper. Due to the limited public information on optimization of this process, intensive internal research and optimization work has been performed in the past years starting from process modelling work up to industrial scale test work.

The availability of the Peirce-Smitch Converter (PSC) is one of the most important factors to maintain a high production in the primary smelter. The campaign lifetime should be as long as possible to achieve the highest possible production time. The campaign lifetime is mostly limited by the degradation of the refractory bricks inside the vessel. Especially the tuyere zone shows normally a very high wear and determines when repair work has to be done and the PSC goes out of operation. The decision of when the converter has to be (partially) repaired is often taken by tuyere length measurements, which are commonly done in the smelters around the world via a steel hook. Operators are using this steel hook with a scale on it and are pushing them manually through the tuyere. The converter has normally up to around 60 tuyeres, what makes this work time consuming and very exhausting, physically and mentally. In addition, the measurement depends on the experience of the operator and how he is using the hook. Furthermore, it is not really a standardized measurement, the operator could point the tip of the hook to the top, to the bottom or to the sides. Risk associated to high temperature of the converter shell, noise exposure and falling accretions from the off-gas section are the main reasons to remove the operators from this task and the area, where also high vibration and dust is common. Removing the operators is the first reason for the development of an automatic measurement system to measure the tuyere length.

In manganese ferroalloys production, gases generated in the lower part of the submerged arc furnace must rise through the solid charge materials. Poor charge permeability may be detrimental to furnace operation by causing clogging and eruptions which, in addition to being a safety hazard, reduce productivity. Sufficient gas permeability in the furnace is also important to achieve proper preheating and prereduction of the charge material; this is also true if the material is pre-treated in a separate unit. The permeability of manganese ores was investigated by measuring the pressure drop while passing air through a manganese ore particle bed at different velocities. Several particle size distributions were investigated, and measurements were done on both raw and pre-treated ores. It was seen that ores with larger fractions of smaller particle sizes gave a higher pressure drop and fluidized at lower gas velocities. Coefficients in established correlations for pressure drop were calibrated for the tested manganese ores. These calibrated correlations were then applied in numerical flow calculations of typical furnace and pre-treatment scenarios to study the sensitivity of pressure drop and furnace operation to the permeability of the ore material used.

Due to increasing electrification and therefore demand for battery raw materials, their recovery from secondary sources like spent lithium-ion batteries is highly important. One process option is a pyrometallurgical route to enrich cobalt, nickel, and copper in an alloy. In current industrial smelting processes, the contained lithium and aluminum are transferred to the slag phase and are difficult to recover. But especially the recycling of the critical metal lithium will be crucial in the future, also to meet legal requirements. Processing the slag regarding lithium recovery has different drawbacks, such as energy-intensive slow cooling for targeted phase formation and milling, as well as chemical-consuming leaching operations. In literature, approaches for lithium collection in the flue dust are reported as well, but require high temperatures of up to 1800 °C. Alternatively, this study investigates the influence and benefits of an early-stage lithium separation before entering the smelting process with black mass. Therefore, shredded battery material was thermally conditioned under an inert atmosphere at 630 °C. During the thermal treatment, the organic content is removed and the contained lithium is transferred to water-soluble compounds. Afterward, 55% of lithium was selectively recovered by water leaching. Suitable slag systems for smelting lithium-depleted black mass were investigated by FactSage calculations, and experimental implementation resulted in the recovery of 99% Cu, 91% Co, and 93% Ni in the metal phase. Thus, the competitiveness of a combination of early and water-based lithium recovery and pyrometallurgical smelting operation against the lithium recovery from slag or flue dust was proven.

Traditionally, fossil carbon is the most commonly used reductant for metallurgical processes such as ferro-manganese and silicon. An important path to the goal of reducing the CO2 footprint of this industry is to replace fossil carbon sources with bio-based carbon sources. Since the structure of biocarbon is substantially different from fossil carbon, characterizing the biocarbon structure and examining its behavior during the relevant processes are important. Micro X-ray computed tomography (μCT) has been used to analyze and compare biocarbon and fossil carbons’ behavior after exposure to reactive gases such as CO2. The investigated material is a composite mix of biocarbon and fossil carbon. Since μCT is a non-destructive technique, the same grains of carbon have been scanned before and after exposure to the reactive gas. Image analysis reveals the structural changes before and after the reactivity test, and the difference in reactivity of the fossil and biocarbon parts of the grain.

In a new integrated process, HAlMan process, hydrogen, and aluminum are used to produce metallic manganese, aluminum-manganese (AlMn), and ferromanganese (FeMn) alloys with low energy consumption and carbon footprint. In this process, hydrogen gas is used to pre-reduce manganese ores and obtain intermediate Fe- and MnO-containing pre-reduced ore. The MnO content of this material is further reduced at elevated temperatures by aluminum in a smelting-aluminothermic reduction process. The main product of the process is metallic Mn, Al-Mn alloy, or ferromanganese, depending on the process feed chemistry. In the present work, the experimental results on the hydrogen reduction of manganese ore are presented and the effect of process conditions such as reduction temperature is evaluated. It is shown that the microstructural properties of the reduced ore depend on the process temperature, and the rate of ore reduction is higher at elevated temperatures. In addition, the smelting-aluminothermic reduction step is discussed and it is shown that the process is flexible to produce a variety of metallic products. Mass and energy balance calculations are presented and it is shown that the energy consumption for the process is lower than the state-of-the-art technology of the submerged arc furnace. It is revealed that the process is sustainable regarding the valorization of Al-dross industrial waste. It is shown that ferromanganese production by this process will prevent the emission of about 1.5 t CO2/t metal, with less practical challenges to produce low-carbon ferromanganese. The implementation of the HAlMan process on a pilot scale through an EU project is presented and it is shown how the process products can be used to make commercial metal products, and also the process products can be valorized to establish a sustainable process for the future ferroalloy industry.

The design and operation of the electric furnace has undergone significant advancements over the past several decades with the smelting industry moving towards increased crucible power density and maximizing operating efficiency. The push towards higher efficiency coupled with more challenging operating conditions, such as lower quality and more variable ore grades, has necessitated the evolution of furnace instrumentation and advancement of control systems to ensure safe and efficient operation. This chapter is focused on the progression of the instrumentation and automation required to facilitate operation and mitigate risks associated with high intensity furnace operations. Emphasis is placed on automated furnace feeding using radar instruments for feedback control. This is a somewhat recent development that continues to evolve and improve consistency of operation. The outcomes are improved performance, greater operational efficiency, and potential reductions in carbon emissions. Examples from two high-power, shielded-arc operations that rely on accurate bath coverage are presented herein. Another important aspect in optimizing furnace operational efficiency is the integration and coordination of the upstream and downstream equipment with the furnace operation. Additionally, this chapter describes some recent advancements in instrumentation, some of which are under development, that will continue to shape the next generation of metallurgical furnace operations. In the context of climate change and greenhouse gas restrictions, process efficiency improvements offered by technologies such as those described herein are becoming increasingly important to reduce the carbon footprint within heavy industry.

The process chemistries of pyrometallurgical processes are becoming increasingly complex; computational tools capable of predicting the phase equilibria and the mass and energy balance of the multicomponent slag/metal/matte/speiss/gas system are required for optimizing the operation of existing and the development of novel processes. In the present study, the phase equilibria of the PbO-ZnO-FeO-FeO1.5-MgO-SiO2 system in equilibrium with metal or air were studied using the equilibration and quenching technique, followed by the use of an electron probe X-ray microanalysis (EPMA) to measure the phase assemblages and compositions of equilibrated samples. The newly obtained experimental phase equilibria data addressed gaps and inconsistencies in the available literature data and were used for the optimization of thermodynamic model parameters describing the complex multi-component system. The present work was a part of the integrated experimental and thermodynamic modeling research program on the phase equilibria of the Cu-Pb-Fe-Zn-Ca-Si-O-S-Al-Mg-Cr-As-Sn-Sb-Bi-Ag-Au-Ni-Co slag/metal/matte/speiss system. The applicability of the research program results to modern industrial needs was demonstrated by the development of the mass and energy balance of a zinc slag fuming process in Kazzinc. The potential for reducing coal consumption per unit of cleaned slag was demonstrated.

Nickel sulfide concentrates are important source for production of battery-grade nickel sulfate. They are commonly associated with cobalt, PGMs and may contain significant amount of copper. Recycling of electronics and batteries would bring even more copper into the process. Sustainable operation of such processes requires accurate prediction of the thermochemistry fundamentals. Thermodynamic calculations are used to predict relationships and optimize key operational parameters such as oxygen partial pressure in the furnace, compositions of slag, matte and metal, as well as conditions of formation of solids, particularly spinels. These calculations must rely on self-consistent thermodynamic databases developed based on targeted experimental results. Present study reports recent experimental work undertaken as part of the integral study to assess and improve the thermodynamic database for the Ni-Cu-containing phases. Experimental methodology consisted of high-temperature equilibration, quenching of the samples, and electron-probe X-ray microanalysis of the coexisted phases. Nickel distribution coefficients among slag, matte, and metal phases have been calculated based on measurement results. The application of EMPA analysis and FactSage calculations has been demonstrated on the example of Anglo-American process.

In current bath smelting and converting operations, submerged gas injection, bath temperature measurement, and bath composition sampling are three separate systems often requiring smelter operators to physically be above or behind the vessels. Low-pressure tuyeres are prone to plugging, which requires mechanical punching. Bath temperature measurement is sometimes automatic yet cumbersome. Bath sampling to determine matte grade is typically manual and risky. Our vision for the industry is that all three tasks, meaning gas injection, bath temperature measurement, and matte grade determination, should be performed by “intelligent tuyeres” without any human intervention, and therefore safer for operators. This chapter describes the principle and early development of this smarter and safer tuyere, which consists in implementing sonic injection for stable and punchless blowing in combination with optometric sensors to measure bath temperature and matte grade through the punchless tuyeres that continuously offer a free field of view into the bath. Sonic tuyeres and optometric sensors have been tested or implemented separately at different smelters but not yet together. At this time, the authors are actively seeking the interest and approval of a smelter currently using sonic tuyeres to test their “intelligent tuyere” concept in production.

Historically, global nickel production has been driven by demand for stainless steel, which has represented the majority of the nickel market. However, battery metals are becoming increasingly more relevant in our global response to combat greenhouse gas emissions, as many of our industries move towards electrification, including the automotive industry. The demand for electric vehicles (EVs) will only continue to increase, and the supply of nickel sulfate is a pressing issue that needs to be resolved. While there are many investments being made to increase Class I nickel availability, the expected growth in the EV market may result in short-term supply shortages. This supply issue could be alleviated by ferronickel (FeNi) producers diverting a portion of their output to produce a nickel matte that can then be further processed into nickel sulfate. This paper reviews the methods currently practiced in industry and discusses the operational and environmental implications of producing matte from FeNi.

Refractory corrosion by slag is among the major causes of refractory deterioration and the subsequent maintenance shutdowns, resulting in downtime and loss of product. In the context of sustainability, the relatively short service life of refractories remains one of the challenges to the steelmaking industry yet to be solved. The initial conditions and process parameters; e.g., slag composition, additives, and bath stirring affect the kinetics and thermodynamics of chemical reactions; i.e., the carbon oxidation and MgO dissolution involved in the refractory-slag system, leading to the eventual loss of refractory lining. To better understand the chemical reactions taking place at the refractory/slag interface, post-mortem samples were microstructurally characterized using scanning electron microscopy coupled with energy-dispersive spectroscopy. Thermodynamic assessments of the system were also performed using FactSage™ v8.2 software and databases to identify the extent of chemical reactions. The obtained results indicated that refractory corrosion is mainly controlled by simultaneous refractory-slag chemical reactions and the mass transport of slag in the porous body of refractory, the details of which are discussed in the present work.

Resolving the modern society challenges, such as sustainability, metal scarcity, and global warming, results in the increased complexity of the process streams in pyrometallurgy, that in turn requires accurate prediction of high temperature chemistries. Integrated experimental and thermodynamic modelling research program on characterization of the complex multi-component multi-phase gas-slag-matte-speiss-metal-solids system with the Cu2O-PbO-ZnO-FeO-Fe2O3-CaO-Al2O3-MgO-SiO2-S major and As-Sn-Sb-Bi-Ag-Au-Ni-Co-Cr-Na minor elements is under way in response. The experiments involve high temperature equilibration in controlled gas atmospheres, rapid quenching, and direct measurement of equilibrium phase compositions with quantitative microanalytical techniques including electron probe X-ray microanalysis and Laser Ablation ICP-MS. Particular efforts are aimed at the improvement and development of analytical techniques. The thermodynamic modelling is undertaken using FactSage software package with advanced thermodynamic solution models. The continuing development of research methodologies has resulted in significant advances in research outcomes. Implementation of the results of fundamental studies involves ongoing collaboration of researchers and industry technologists and advanced professional training. An overview of recent progress in research, implementation and applications in industrial practice will be presented in the paper.

There is a lot of potential in reusing metallurgical slag in geotechnical applications, with the primary concern for it is the susceptibility to natural leaching. A complex approach is essential to decrease the environmental impact of slag reuse and thus enhance the recycling of industrial slags. The current study is fundamental and focused on leaching behavior of amorphous slags in the CaO-“FeO”-MgO-SiO2 system with heavy elements Pb and Cu. Compositions of synthetic slags are selected using the high-temperature equilibria studies and the predictions of internally developed thermodynamic models. The samples are prepared under laboratory controlled conditions and carefully characterized. Experimental technique for bulk leaching experiments is established to investigate pH-dependent elusion of elements into the leaching medium. Concentrations of the metals in the leachate is measured using ICP-MS. In addition, the micro-leaching tests devoted to investigation of slag surface structure before and after leaching are developed. Novel analytical techniques such as SEM/EPMA, TEM and XPS are implemented for analysis of slag-aqueous solution interface. Understanding of dissolution of amorphous glass phase that is present in all existing metallurgical slags is a critical step to provide a link between the chemical and phase composition of slags at high temperature, the cooling regime and leaching phenomena.

The crucible of metallurgical assets should be considered alongside the ore, the backbone of the smelting industry. Without it, molten metal production and transport vessels could not operate. Loss of integrity in the crucible is catastrophic for an operation, risking worker safety, production availability, and capital expenditure. In the pyrometallurgical process, specifically in the furnace crucible, the quality of refractory lining, the feed or calcine, and the feeding system is the bottleneck of the entire plant. Therefore, it is paramount that an accurate understanding of the refractory lining condition is maintained. The traditional approach to managing risk has persisted in a planned and proactive maintenance strategy, where risk is controlled by completing repairs at fixed intervals. In some cases, this has resulted in overly conservative and costly repair schemes and, in other cases, in easily avoidable furnace leaks and run outs. An ideal monitoring and maintenance strategy is a data-driven, risk-based, and predictive strategy in which data from furnace instrumentation and operator observations are combined with management targets to adjust the operation and plan proactive repairs. This more advanced approach results in safer operations, minimized downtime and repair costs, and reduced industrial waste/emissions.This chapter describes our novel life cycle management method and its implementation of Risk-Based Inspections (RBI) and refractory management for pyrometallurgical process vessels and furnaces. In support of these management tools, case studies are presented to demonstrate how a data-driven predictive refractory maintenance strategy allows the operation of the furnace beyond its campaign life prediction.

Slags are one of the postproduction wastes in iron and steel-making processes. Iron and steel production industries are looking for new technologies to recycle and reuse slags. There is a high potential for the recovery of iron from slags. Furthermore, the composition of slags should be adjusted to make them ready to be used in the cement and concrete industry. In addition to hydrometallurgical methods, reduction and remelting of slags can be considered an effective pyrometallurgical route to recycle and modify steel slag composition. In this study, hydrogen reduction of LD slag samples at different temperatures has been investigated. The results showed that the rate of the reduction increases significantly by increasing the temperature and almost all the Wüstite reduces to metallic iron at 900 °C and 100% hydrogen. It was also found that calcium hydroxide decomposes at 500 °C, calcium decomposes with increasing temperature, and vanadium is spread to calcium silicates and ferrites.

An increased interest in reducing emissions from carbon-based processes for steel and other raw materials has driven exploration of other energy and reagent-based alternatives such as the use of hydrogen, in this case as the main reducing agent for steelmaking. In some cases, the analyses are based on overly simplistic models of the hydrogen steelmaking process that assume a stoichiometric supply of pure hydrogen for the intermediate reactions and final reduction reaction, FeO + H2 = Fe + H2O. This latter reaction is however strictly limited by thermodynamic considerations – significant excess hydrogen is necessary to assure full conversion of the iron oxides, and a substantial amount of that hydrogen remains in the outlet gases. This hydrogen, along with the thermal energy contained in the outlet vapor, must be recovered if the process is to be energy efficient or even sustainable. Higher temperatures favor the reduction reactions, but complicate heat recovery and removal of the water vapor by condensation and any remaining water vapor recycled to the shaft inlet will reduce the hydrogen reduction efficiency. We present a SysCAD simulation energy and mass balance model considering thermodynamic equilibrium of the hydrogen steelmaking process which highlights the key issues, both theoretical and practical, that need to be addressed for such processes to be economically viable at the large scales necessary for hydrogen to replace carbon-based fuels in the steelmaking industry. A custom thermodynamic system database for the H2-steelmaking process was developed for this model and used within SysCAD and its Thermodynamic Calculation Engine (TCE) capabilities coupled with the heat and mass balance.

The Direct Reduction of Chromite (DRC) process has the potential to reduce energy consumption and reduce Greenhouse Gas (GHG) emissions for ferrochrome production, as needed to produce stainless steel and other specialty alloys. In the DRC process, Fe and Cr oxides in chromite are reduced at temperatures below their latent heat of fusion which substantially lowers energy requirements, resulting in the production of M7C3-type ferrochrome. In the present work, induration by oxidative sintering, reductant size, and reduction temperature were investigated at the exploratory level to advance our understanding of the DRC process. Induration by oxidative sintering was notably found to slow reaction kinetics and delay metallization, whereas smaller reductant sizes accelerate reaction kinetics. The influence of temperature on reaction kinetics was investigated in several experiments, and an energy barrier identified which may justify a DRC processing temperature of 1320 °C. After an extended time at 1320 °C, the amount of Cr present in the spinel and slag as measured by microprobe analysis are less than 0.43 wt% Cr as Cr2O3, which confirms high degrees of Cr metallization.

The capacity of different polymers to effectively work as a reductant depends on the thermal and chemical energy contained in them. A knowledge of the reducing potential of different plastics is required to assess the qualitative and quantitative characteristics of the plastic wastes, whether individually or mixed. This study aims to investigate the reduction potentials of different plastics, namely polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), and acrylonitrile styrene-butadiene (ABS). The pyrolysis of different polymers, individually and combined, was studied. Thermogravimetric and off-gas analyses, were conducted to understand the decomposition behaviour of different polymers, and the temperatures wherein the gaseous constituents are released. The thermodynamic basis for the reduction of hematite (Fe2O3) using plastic wastes was derived, and the reducing potential of the polymers was experimentally studied by reacting the polymers at 1200 °C. The knowledge gained from the study will offer a comprehensive understanding of using polymers from plastic wastes as reductants for a broader range of metallurgical applications.

Low-grade ore processing plants require large amounts of energy and water. The design production targets of a plant are hard to reach due to high variability of ore mineralogy and hardness. Coordination between grinding, classification, flotation, and water recovery processes is a must. A novel approach using a Digital Twin was designed to maximize copper production and water recovery. Instead of the traditional metal recovery, a Net Metal Production Rate operational strategy is presented to determine the optimal mill throughput. Process data, together with machine learning algorithms using dynamic grinding, flotation, and tailings water separation models, were implemented to allow for synchronized ore processing. The rheological characteristics of the pulp enable the prediction of the pulp/paste boundaries to be respected. The new capabilities provided by the computational capabilities for advanced cloud-based analytics enable remote access. This novel approach is described to process low-grade ores with an increased water recovery in a profitable and sustainable manner.

The steel industry is transitioning to clean energy and away from fossil fuels, and as a result, many new technologies are being adopted to change the process and eliminate the reliance on fossil fuels. Many steel producers are moving away from traditional cokemaking and blast furnace processes due to their carbon emission intensity, and expanding the use of direct reduced iron and electric arc furnaces. The steel industry is also considering new technologies such as hydrogen and carbon capture and storage/utilization as pathways to reach net zero. Reducing GHG emissions from steam generation is an additional strategy that works in tandem with these other strategies, and it is the focus of this abstract.Steam generation is essential to the operation of integrated steel mills, and is traditionally generated with by-product fuels, natural gas, and/or oil. As more coke plants and blast furnaces are shutdown, there is less available by-product fuels for steam generation. Reducing CO2 emissions from steam generation can be seen as a “low-lying fruit,” and with increasing carbon tax in many jurisdictions, there is also the potential for financial savings by using technologies such as waste heat recovery, electric boilers, and thermal energy storage. In this abstract, we will discuss these potential methods to eliminate GHG emissions from steam generation in integrated steel mills.

Previous research at low power levels has shown that kimberlite ores undergo fracturing during microwave treatment. However, a detailed study of the application of high-power microwave-assisted comminution is lacking. In this paper, the microwave heating behaviour of a volcaniclastic kimberlite (VK) was investigated at both the bench and the pilot scales. Firstly, to elucidate the heating mechanisms, permittivity measurements were combined with thermogravimetric analysis and differential scanning calorimetry studies. Secondly, bench-scale microwave (BMW) testing confirmed that the VK was very microwave responsive with significant macrofracturing, especially at a coarser particle size. Thirdly, preliminary pilot-scale microwave (150 kW) tests were carried out in both batch processing (BP) and continuous processing (CP) manners. The BP tests experienced macrofracturing, while the CP tests did not. These results demonstrated the importance of residence time and hence specific energy input. Fourthly, timed SAG mill grinding tests were performed on the following samples: as-received (AR), BMW, BP, and CP. Both the particle size distributions and the quantity of fines (<850 μm) were determined. Compared to the AR sample, the BMW and the BP samples generated more fines, while the CP sample yielded a coarser particle size distribution. Thus, the amount of fines generated was related to the total microwave energy input. Finally, more research is planned both to develop an improved understanding of the heating mechanisms and to enhance the process at the pilot scale.

Current and future social imbalances such as increasing metals demand for electromobility, need for CO2-free electrical power, reduction of mine wastes, and declining supply of elemental sulfur from oil and gas production all can be compensated for by efficient recyclingRecycling of tailings. Upgrading tailings into a pyrite concentrate allows for valuable metals recovery through a combination of long-proven and modern technologies. Used primarily for the production of sulfuric acid up to the 1970s, the mining industry is now revisiting pyrite roasting technology to process existing waste materials. The latest reference plant for this technology is Eti Gübre Mazidagi in Turkey, a highly integrated industrial complex that created multiple revenue and value streams, using a sustainable approach to metals (cobalt, copper, zinc, gold, and silver) recovery, acid production, and finally steam and electric power production with no CO2 emissions. Over the last 70 years, Metso Outotec has built more than 160 pyrite roasters, whose success has proven the efficacy of the pyrite roasting process. The paper describes typical key parameters required for comparing potential small and large investment projects.

Hydrogen (H2) gas has been proposed as an attractive candidate to replace carbon in metal production. Oxide reduction with H2 releases water (H2O) as the off-gas rather than carbon dioxide (CO2). This has been shown to be feasible, for e.g., iron oxides and some manganeseManganese oxides. However, common, more stable oxides, such as manganeseManganese monoxide (MnO), are subject to thermodynamic limitations, which prohibit reduction with H2. Utilizing monoatomic or ionized hydrogen (H or H+), abundant in hydrogen plasma, makes the hydrogen-oxide reactions more favorable and allows reactions such as: 2 H + MnO → H 2 O + Mn $$ 2\mathrm{H}+\mathrm{Mn}\mathrm{O}\to {\mathrm{H}}_2\mathrm{O}+\mathrm{Mn} $$ H + + M n O → O H + M n + $$ {\mathrm{H}}^{+}+\mathrm{MnO}\to \mathrm{OH}+{\mathrm{Mn}}^{+} $$ The current work demonstrates experimentally the production of metallic manganeseManganese by exposing sintered MnO to hydrogen plasma. The hydrogen plasma was generated by passing H2 through a plasma torch. This paper will present the experimental setup and method, as well as characterization of the reaction products. Hypotheses for the reaction paths are presented and discussed in the context of thermodynamics and solidification theory. Furthermore, computational fluid dynamics is used to support the discussions via mathematical modeling of temperature- and flow fields.Although substantial research is still needed, the presented results demonstrate that hydrogen plasma allows for reduction of more stable oxides than is possible with H2, and that hydrogen plasma-based technologies can be used for manganeseManganese production.

The mass application of lithium-ion batteries (LIBs) will inevitably lead to the accumulation of a huge amount of battery waste. Recycling scrap batteries offers a means to alleviate environmental damage, resource depletion, and waste accumulation. Especially since the lithium content of waste LIBs is much higher than the mineable grade of lithium ores, recyclingRecycling it will bring huge economic benefits. Yet, the overall recovery rate of lithium from these secondary resources is still less than 1%. To ameliorate this situation, a multistage method for direct selective leaching of lithium from industrial-grade, mixed LIB waste is proposed, to efficiently realize the selective leaching and enrichment of lithium. Through the combined action of formic acid and hydrogen peroxide, the single-stage leaching rate of lithium can exceed 97%, while leaching rates of impurity metals such as nickel, cobalt, manganese, copper, aluminum, and iron remain below 1%. The multistage leaching process developed in this method increases the concentration of lithium in the leachate from 1.8 g/L to 7.88 g/L, maintaining Li leaching efficiency above 94.07%. The advantages of this method are high lithium leaching efficiency, exceptional selectivity, simple operation under ambient conditions, and environmental friendliness. Moreover, this method avoids complex and lengthy powder separation steps, reducing the cost and consumption of energy. This method can be applied to a variety of different compositions of LIBs waste, with excellent industrial application prospects.

The world’s steel industry contributes 7–9% of global greenhouse gas emissions. This is principally from blast furnaces, basic oxygen steelmaking, sintering and pelletising. The push to reduce carbon emissions will see a change, where green high-grade magnetite with ≥68% Fe grade becomes the preferred feedstock for the steel industry, over the lower-grade hematite. This will necessitate changes to flowsheets to remove carbon footprint. The magnetite concentrates would command a premium in price. The largely hematite Pilbara iron ores are most at risk with this change. The global steel industry faces massive technical challenges to transition a zero-carbon footprint. Both blue and green hydrogen may have a role to play in this transition. Examples of new technologies to produce higher-grade magnetite concentrates and the options for steel mills to move away from conventional blast furnace operations are discussed. These include hydrogen reduction, MIDREX, CIRCORED, HYL, PERED and others. Carbon capture and storage are possible options but are not yet a commercial alternative. Biomass is not an alternative as it still has a carbon footprint. Hydrogen reduction of iron ores circa 62% iron is possible but requires magnetic separation to remove silica and alumina to achieve ≥68% iron. For Pilbara hematite ores, this is one solution going forward. Hydrogen is more explosive than natural gas, requiring nitrogen purging at start-up and shutdown, representing a significant operating risk. Its transport and storage is a challenge, as it causes embrittlement of steel. Ammonia has been suggested as alternative.

Simulation platforms are applied to design and test alternative approaches to integrated management, including scheduling and planning over different timeframes. For mining and metallurgical systems, these platforms can be initially developed using mass balancing in conjunction with discrete event simulation (DES), and then detailed in later engineering phases by hierarchically embedding models and submodels to represent critical risks and opportunities. A promising application of DES is for implementing machine-learning enabled control strategies within mining and metallurgical systems, first by simulating the as-is system and then quantifying the effect of enhanced approaches. The kinetics of individual unit operations can be detailed within the mineral value chain, by embedding time-adaptive finite difference (TAFD) into DES; the resulting DES-TAFD hybrids are computationally efficient and can simulate hundreds or thousands of operational days in a matter of minutes. DES platforms support modern approaches to integrated management by simulating and refining alternate control strategies, and can enable system-wide improvements that balance production metrics with environmental considerations. In particular, the current presentation discussed experiences in embedding geological variation into DES of mining systems, and thermochemical models into DES of extractive metallurgical plants. Well-defined operational modes provide integrated responses to changing risk profiles, leading to better outcomes.

While much work on CO2 reduction is on carbon capture, permanent storage of carbon dioxide in the coming decades is critical to fight climate change. Carbon sequestration in minerals is one of the most practical solutions for permanent CO2 sequestration. Carbon sequestering minerals are processed for base metals extraction by ultramafic mines. Passive carbonation of these minerals in a tailings storage facility is a virtually cost-free method of permanent CO2 sequestration. Until now, mine operators have not had the tools for managing their tailings storage facilities (TSFs) for maximum carbon storage. Recent work by Canada Nickel Company and Queen’s University has shown how optimizing the TSF can substantially improve carbon storage. The key drivers for CO2 storage have been studied experimentally and extended to tailings deposition through a multivariable model. The implications of this work will be presented.

Technological innovations have led to two phenomena: the unprecedented consumption of mineral resources, including critical and strategic elements, and the generation of disproportionate amounts of electronic waste (e-waste). As a result, e-waste has become the fastest growing component of the municipal solid waste stream [1]. With a near doubling in just 16 years, the global amount of e-waste is expected to reach 74.7 million metric tonnes (Mt) by 2030 [2]. Moreover, by the end of 2022, 13.1 million tonnes of e-waste will be generated in America, of which only 9.4% will be recycled. The value of metals lost in the 180 kt/year of Canadian e-waste can be estimated at over $CAD 550 million [2].

The history of mining in Canada is long and many established construction techniques and methodologies are ingrained deep within the systems and culture of mining construction. With resources becoming more technically and economically challenging to access, mines going deeper, and processing plants required to meet more stringent environmental regulations, the mining industry in Canada is evolving technically. Projects are learning quickly that the implementation of more sophisticated equipment, materials, and engineering designs requires more knowledgeable construction quality oversight to ensure engineering designs are implemented as intended. Without an established quality control program, procurement and construction execution can be greatly affected by poor fabrication or installation quality which drives late delivery of projects through rework and delayed commissioning. This paper provides observations and recommendations with examples drawn from the author’s personal experience with underground mining projects and surface processing plants completed over the past 14 years. By applying a basic construction quality framework, ensuring oversight by qualified and competent personnel, and ensuring the correct level of staffing resources, such construction issues can be avoided, resulting in smoother start-ups and more successful project outcomes.

Developing quantifiable environmental social and governance (ESG) criteria is a challenge facing mining companies today and an opportunity to differentiate themselves. With a large focus recently on GHG emissions and clean energy, there is a push for companies to demonstrate “environmentally friendliness” and “sustainable supply.”

The objective of this paper is to estimate that value of acid-generating tailings beyond what any residual mineral value lost in the tailings might indicate. Specifically, the value of sulfuric acid produced by acid-generating mine tailings will be estimated. Today, the value of sulfuric acid in a tailing effluent stream is negative and equal to the cost of using lime to neutralize the tailing stream. However, there potentially is more value in sulfuric acid if the treatment process was to focus on changes to an electrochemical process such as the Stiller process. A process circuit is proposed to treat acid tailings effluent. Leveraging the expected chemical reactions occurring in the Stiller cell, stoichiometric-based models are defined for the products (electricity, hydrogen, and metal salts) produced and materials consumed (iron anode) as a function of effluent pH and flowrates. Leveraging the Zinck and Griffith data review of acid drainage treatment operations in Canada, the models are used to estimate the value that can be captured with the proposed electrochemical acid tailings effluent process. The subsequent discussion explores the possibility of expanding the proposed circuit to that proposed in Radziszewski and Blum, a complementary means to prediction acid tailings value, challenges to development, and possible future impacts of the proposed electrochemical approach to treating acid-generating mine tailings.

The silicon and ferroalloy industries in Norway have traditionally relied on fossil carbon products as reductants for their respective process. Efforts to reduce fossil CO2 emissions by introducing biocarbon have already begun, and targets of 25–40% biocarbon use by 2030 have been set by various producers in Norway. An understanding of the effects of the physical properties of the carbon on the process must be obtained so that the transition can take place with minimal process interruptions.It is well documented that charcoal is more friable than traditional fossil carbons, particularly during transportation and handling. Major issues related to the fines generation are concerning material loss, effect of furnace performance, personal health and safety concerns by inhalation of particles, and possibility of dust explosions. The strength of unreacted material, the cold strength, can give good information about the dusting potential of a material; however, many methods exist for these evaluations. In this work, an overview of the raised issues concerning dusting, and methods to evaluate cold strength in relation to dusting, is included, as is some relevant comparisons between charcoals and traditional carbon sources with respect to tumbling strength.

During industrial production of ferroalloys (FeMn/SiMn) and silicon (Si), carbon materials are used as the main reductants. The selection of carbon materials affects energy consumption, operational stability, and ultimately the yield and quality of the final product. Substituting fossil carbon with biocarbon as reductants is meant to reduce the CO2 footprint and is currently being investigated in the ferroalloy industry. The properties of various fossil reductants and charcoal and their impact on ferroalloy production have been investigated and are compared in this study. The “Boudouard reaction” which is the CO2 reactivity of carbon results in an increase in carbon and energy consumption. Therefore, it is important to have knowledge about the reactivity of the chosen reductant and its impact. The reactivity is dependent on various factors, including physical properties and chemical composition. In this study, methods for studying CO2 reactivity and the results from investigations of various carbon materials are presented and discussed. Studies show that charcoal has the highest CO2 reactivity due to its physical and chemical properties. In addition, the effect of alkalis in charcoal on CO2 reactivity is also addressed. The high amount of fines generated inside the ferroalloy furnace can reduce the charge permeability and have a negative effect on furnace operation. Thus, the thermal strength of the carbon materials is an important property for its use. Methods for studying thermal strength and fines generation and results from investigations of various carbon materials have been analysed and are presented and discussed. The lower thermal strength of charcoal compared to traditional fossil carbon sources may limit its use. But methods to mitigate this through the use of bio-coke are presented.

The design and engineering of hydro- and pyro-metallurgical process circuits using new technologies for the extraction and disposal of materials is challenging and driven by numerous inputs including bench test work outcomes, pilot-level demonstrations, process simulations, operability requirements, personal experience, and capital constraints.This paper discusses these issues in the Canadian-European context and covers the extraction of gold from an arsenopyriteArsenopyrite gold concentrateConcentrate. A systematic study was performed aimed at using DST’s GlasslockGlasslock arsenicArsenic removal and stabilization process to increase the profitability of a mining operation that produces lead, zincZinc (Zn), and gold-bearing arsenopyriteArsenopyrite concentrates.The ore body is refractoryRefractories to direct conventional cyanidation and requires suited extraction approaches to reduce the environmental liabilities associated with arsenicArsenic and maximize the payable gold revenue. The gold leachingLeaching results using DST’s CLEVRCLEVR process have also shown that a gold extraction yield of over 71% could be achieved on the calcine as opposed to a 53% yield when using cyanidation.Since the gold concentrate is facing market penalties due to high arsenicArsenic levels, the added value proposed by DST is the GlasslockGlasslock process to remove and stabilize the arsenicArsenic at costs inferior to market penalties. Moreover, the results of the test program demonstrated the feasibility of sequestering arsenicArsenic trioxide (As2O3) into a stable arsenical glassArsenical glass. A glass containing 16.3% arsenicArsenic was produced and benchmarked against the EN 12457-1 norms and protocol for stability.Particular focus is placed on some practical aspects of DST process design and engineering and the impact that these decisions can have on the operation.

Zinc is one of the main non-ferrous metals, and it is currently the fourth most widely consumed metal, after iron, aluminum, and copper. The rate of its use has risen rapidly in recent decades. The requirement to meet growing zinc demand will require zinc smelters, and those in China, in particular to increase utilization rates. The demand for the next 5 years new smelting capacity will be required, to increase the capacity of zinc smelting outside of China. Zinc smelters in the European Union are currently facing a number of challenges, including high-energy costs. It is a significant opportunity for Turkey, which has several zinc sources. There is not sufficient zinc metal production in Turkey. Zinc sources are exported abroad as zinc concentrate. Turkey’s zinc trade deficit has reached $4 billion since 2011. Zinc smelting facilities are needed both for domestic production and to support lead-zinc mining and meet domestic metal demand. Since smelting facilities are an industrial application, the number of academic studies is very low and hardly ever encountered in the literature. In this context, new studies regarding zinc smelters are extremely important in order to develop a new approach for building a zinc smelter in Turkey. This study will provide an approach to the necessity of a zinc smelter in Turkey and examine why a zinc smelter in Turkey is extremely important and may open new doors. This study reviewed the situation of the zinc industry in Turkey, including the global first and end uses of zinc.

Resource-use efficiency is considered a critical factor in achieving the sustainable development goals (SDGs) provided by the United Nations. Improving energy efficiency in the mining and mineral processing industry can help to meet environmental goals and result in significant economic savings. Currently, mining consumes approximately 10% of global energy with a significant portion of 30–70% in the extraction of valuable minerals [1–3]. Recently, microwave irradiation has emerged as an economically promising pre-treatment technique to reduce grinding resistance and improve mineral recovery. Over the course of past few decades, there has been a growing interest in using microwave treatment for the application in excavation and comminution of rocks/ores by [3–7]. Kingman et al. [8] carried out an experimental study to investigate the effect of short-term treatment with high microwave power levels on copper carbonatite ore. Their findings revealed that subjecting the samples to 15 kW of microwave power for as short as 0.2 seconds with an energy input of 0.83 kWh/t results in a 30% decrease in impact breakage parameters.

The recent increase in global demand for the essential minerals/metals that support the production of alternative green energy sources raises serious concerns about the development and deployment of energy-efficient technologies in mining operations to reduce carbon footprint and meet climate change mitigation objectives. Given the urgency of relieving carbon footprint, this paper describes the main benefits of incorporating unique advanced process control (APC) technology to optimize nickel reduction kiln operations, which leads to a significant decrease in carbon emissions. ANDRITZ’s Advanced Control Expert (ACE) APC strategy uses a hierarchical structure consisting of two layers of control technology. The base layer stabilizes the key process variables using a proprietary Multivariable Model Predictive Control (MPC) tool, commercially known as BrainWave®. The top layer performs as the supervisor, which is a rule-based algorithm for automatic management and optimizationOptimization of process objectives. ANDRITZ’s APC solution has been deployed on various mineral processing applications globally. This work presents an overview of the strategy and results obtained for a recent application on nickel reduction kilns in Asia. The technology fulfills the performance conditions essential to attain optimized operation, aligned with the effort of lowering greenhouse gas emissions. The performance results show a reduction in fossil fuel consumption of 4–7%, a throughput increase of 2–4%, and a significant decrease in operator workload and human interventions. The control performance assessment also shows a variability reduction of 40–50% in the temperature profile, which improves the nickel product quality.

The rare earth elements (REEs) are a group of 15 lanthanides, yttrium, and scandium which exhibit optical, electronic, and catalytic properties [1]. This unique characteristic has progressively established REEs as strategically critical raw materials for an array of applications in renewable energy, advanced electronics, telemedicine, superconductors, low-energy fluorescent bulbs, aircraft, automobiles and petro-refinery catalysts, and many other high-tech products [2, 3]. Consequently, the global demand for REMs is constantly increasing in spite of its controlled trade by the major contributor China that delivers >90% of the worldwide production. South Korea is one of the countries who is lacking the natural minerals of REEs; however, the country is one of the topmost consumers of rare earths in the manufacturing of electronics and automobiles industries [4]. The immense push to minimize its dependency on REEs’ import from outside countries, South Korea is looking to exploit its potential vein-deposited REEs’ reserves. Nevertheless, the veins have been found to contain a significant number of total REEs; their sustainable processing is imperative due to the associated environmental issues and high processing costs to deal with this low-grade ore [4, 5].

It is almost impossible to find a consistent and comprehensive classification system for Canadian mining and metallurgical wastes including both their techno-economic potential and environmental impact. In addition, the diversity of the mining and metallurgical wastes in terms of physicochemical properties necessitates different valorization routes, which is a multidisciplinary scientific and technological challenge. Therefore, this project aims at developing a smart database for waste based on a systematic and knowledge-based methodology. The circular economy, critical mineral plans of Canada and its allies, and environmental impact are among the aspects considered in the present work. The smart database will consist of several data libraries, modules, and a search and decision-making algorithm. The data libraries are categorized into data about local wastes such as composition and mineralogy, data about process specifications, economic data, and related technical references. Currently, five projects are active in parallel: (1) data collection of mine wastes in Quebec province, (2) data collection of mineral processing wastes, (3) data collection of hydrometallurgy and pyrometallurgy wastes, (4) potential wastes for CO2 capture and storage, and (5) development of a search and decision-making algorithm. So far, the focus of the project has been on the wastes containing bismuth, cobalt, lithium, manganese, nickel, tellurium, and vanadium, considered critical according to Canada Critical Mineral List.

The mining industry faces increasing pressure to improve sustainability by reducing operations’ GHG emissions, water and power consumption, and chemical usage. MineSense Technologies Ltd. is transforming how mining operations manage their output quality. The company achieves this by deploying ShovelSense® sensors on the buckets of excavators, which precisely measure the grade of every load before it gets dumped into the transport truck. This breakthrough technology enables the mining industry to exploit variations in ore grades with unprecedented accuracy, thereby reducing wasted valuable ore and avoiding the processing of unwanted materials, which can be used to determine the most efficient methods for extracting ore. Consequently, these advancements significantly impact the profitability and sustainability of mining operations.

The global iron and steel industry is responsible for around 7% of global energy-based greenhouse gas emissions, and leading steel producers are committed to ambitious climate action. This paper presents an integrated production cost and carbon emission optimization solution to address the challenges steelmakers are facing to decarbonize their value chain and deal with the impact of carbon pricing on their company’s competitiveness. The solution aims to optimize the total meltshop production cost related to raw material procurement and utility consumption while reducing GHG emissions for primary steel making. The model can calculate scopes 1, 2, and 3 emissions and apply a carbon price to any subsection of the scopes, depending on the application. Simulated case studies demonstrate the cost benefits and GHG reduction and highlight the impacts of direct and indirect GHG emissions. The case studies explore the calculation of scope 1, scope 2, and scope 3 categories 1 (purchased goods and services) and 3 (fuel and energy-related activities) using production data including the carbon intensity impact of purchased scrap materials. The case study found that there is a breakeven point in operating strategy around the current cost of carbon in Canada.