Pyrometallurgical Processes Research Articles

Mechanical activation and physicochemical factors controlling pyrometallurgical, hydrometallurgical, and electrometallurgical processing of titanium ore: A review

In this study, we review the role of mechanical activation in the pyrometallurgical, hydrometallurgical, and electrometallurgical processing of titanium feedstock. Mechanical activation has been shown to decrease the activation energy of chemical reactions, thus enhancing process efficiency and product quality by reducing processing time and energy consumption. Pyrometallurgical processing is energy-intensive and time-consuming. Hydrometallurgy is costly, requires high-grade feed material, and generates toxic waste. Waste generation and process complexity are the major drawbacks of electrometallurgy and solvent extraction. Bioleaching via a mechanically activated pyrometallurgical process can be identified as an alternative method, but the lengthy processing time is the major disadvantage. Mechanically activated titanium concentrate can be used in a finely tuned combined metallurgical process to overcome the challenges and drawbacks in these technologies.

Valuable Recovery Technology and Resource Utilization of Chromium-Containing Metallurgical Dust and Slag: A Review

As a type of metallurgical solid waste with a significant output, chromium-containing metallurgical dust and slag are gaining increasing attention. They mainly include stainless steel dust, stainless steel slag, ferrochrome dust, and ferrochrome slag, which contain significant amounts of valuable elements, such as chromium, iron, and zinc, as well as large amounts of toxic substances, such as hexavalent chromium. Achieving the harmless and resourceful comprehensive utilization of chromium-containing metallurgical dust and slag is of great significance to ensuring environmental safety and the sustainable development of resources. This paper outlines the physicochemical properties of stainless steel dust, stainless steel slag, ferrochrome dust, and ferrochrome slag. The current treatment technologies of chromium-containing metallurgical dust and slag by hydrometallurgy, the pyrometallurgical process, and the stabilization/solidification process are introduced. Moreover, the comprehensive utilization of resources of chromium-containing metallurgical dust and slag in the preparation processes of construction materials, glass ceramics, and refractories is elaborated. The aim of this paper is to provide guidance for exploring effective technology to solve the problem of chromium-containing metallurgical dust and slag.

High-Temperature Phase Behavior of Li2O-MnO with a Focus on the Liquid-to-Solid Transition

The Li-Mn-O system is a crucial constituent of cathode materials used in lithium-ion batteries (LIBs). Numerous research teams have focused on enhancing its electrochemical properties and thermal stability at lower temperatures to develop high-performance cathode materials. However, in the recycling of LIBs in pyrometallurgical processing, the high temperature phase behavior of the Li-Mn-O system is important. Today, there is still a lack of systematic understanding regarding the high-temperature phase behavior of the Li-Mn-O system under well-defined atmospheric conditions, which is highly sought after in the pyrometallurgical process route to increase the recycling efficiency of lithium from spent LIBs. In this study, we investigate the high temperature phase behavior of the pseudo binary system Li2O-MnO under inert atmosphere. Thermal and caloric properties are measured as well as the contact angle at high temperatures to identify the solid-liquid transition. Based on the obtained phase behavior, thermodynamic database of Li2O-MnO within the Calphad framework is developed, where the liquid phase is modelled by the Modified Quasichemical Model (MQM).

Short-Loop Recycling of Nd-Fe-B Permanent Magnets: A Sustainable Solution for the RE2Fe14B Matrix Phase Recovery.

The green transition initiatives and exploitation of renewable energy sources require the sustainable development of rare earth (RE)-based permanent magnets prominent technologies like wind turbine generators and electric vehicles. The recycling of RE-based permanent magnets is necessary for the future supply of critical rare-earth elements. The short-loop recycling strategies to directly reprocess Nd-Fe-B magnet waste are economically attractive and practical alternatives to conventional hydro- and pyrometallurgical processes. This study focuses on the development of a procedure to extract the (Nd, Pr)2Fe14B hard-magnetic phase from sintered Nd-Fe-B magnets. The extraction is achieved through preferential chemical leaching of the secondary, RE-rich phases using 1 M citric acid. Before the acid treatment, the magnets were pulverized through hydrogen decrepitation (HD) to increase the material's surface-to-volume ratio. The as-pulverized Nd-Fe-B powder was subsequently exposed to a 1 M citric acid solution. The effect of leaching time (5-120 min) on the phase composition and magnetic properties was studied. The results of the microstructural (SEM) and compositional (ICP-MS) analyses and the study of thermal degassing profiles revealed that the RE-rich phase is preferentially leached within 5-15 min of reaction time. Leaching of the secondary phases from the magnet's multi-phase microstructure is governed by the negative electrochemical potential of Nd and Pr. The extraction of (Nd, Pr)2Fe14B grains by the proposed acid leaching approach is compatible with the existing hydrogen processing of magnetic scrap (HPMS) technologies. The use of mild organic acid as a leaching medium makes the leaching process environmentally friendly, as the leaching medium can be easily neutralized after the reaction is completed.

Mixed Anionic/Cationic Collectors for Pyrite Flotation: An Experimental and Theoretical Study

ABSTRACT The presence of pyrite causes harmful environmental and metallurgical effects during the pyrometallurgical processes of metals. Hence, various processing methods should minimize the amount in the feed. Meanwhile, flotation is one of the most common methods due to the natural hydrophobic property of the pyrite surface. Based on this premise, this research focuses on the efficiency of pyrite flotation using mixed anionic/cationic collectors as one of the significant factors of flotation. This study is organized and performed in two laboratory and simulation sections. Lab-scale studies consider the kind of collector(s), collector(s) concentration, size, frother concentration, and pH as practical factors. Dodecyl amine (DDA), potassium amyl xanthate (PAX), and Sodium Isopropyl Xanthate (SIPX) are three types of collectors examined in the single and mixed forms for pyrite flotation. In the simulation part, adsorption of a single form and mixed forms of collectors on the pyrite (001) surface and its effects on the wetting property of the surface is investigated using the molecular dynamics approach. In sum, the results of this study show that, although pyrite has the favorable ability of flotation with anionic collectors from the xanthate family (PAX and SIPX) due to its natural hydrophobic feature, the presence of a cationic collector (DDA) significantly enhances its flotation performance so that a 1:1 mixture of DDA and PAX with a concentration of 15 for each collector, at pH 7, and the presence of an A65 as frother (30 ), increases the flotation recovery of pyrite by more than 95%.

Comparison of waste lithium-ion batteries recycling methods by different decision making techniques

Today, to reduce fossil fuel consumption and to prevent gas emissions that are increasing day by day, vehicles working with electrical energy have started to be produced and developed. The environmental impact of the batteries of electric vehicles, which are increasing in number, is an undeniable fact and is predicted to be a major problem. In this study, three different alternative recycling processes were selected for waste lithium-ion batteries (LIBs), namely pyrometallurgical process, hydrometallurgical process and direct recycling.These processes were compared in terms of their technical, economic, environmental and social aspects using a Multi-Criteria Decision Making (MCDM) approach.. From this point of view, in this study, entropy method which is an objective method was used to weight the criteria and Analytic Network Process (ANP) and TOPSIS methods were used to prioritise the alternatives in order to determine the best process for the recycling of waste LIBs. The alternatives were determined as being pyrometallurgical process, hydrometallurgical process and direct recycling, and these alternatives were evaluated in terms of environmental, economic, technical, and social dimensions. Afterwards, sensitivity analysis was performed. The ranking results showed that direct recycling is the best alternative (with values of 0.68 and 0.8101 for ANP and TOPSIS, respectively). In addition, sensitivity analysis was applied for the robustness of the results. As a result of the sensitivity analysis, direct recycling was found to be the best alternative.

Recent Work on the Recovery of Rare Earths Using Ionic Liquids and Deep Eutectic Solvents

With the development of smart technologies, the use of rare-earth elements (REEs) has been widespread; thus, their importance as valuable and strategic metals has been boosted to levels never known before. Due to their scarcity in the Earth’s crust, the recovery of these elements from secondary resources has also witnessed further developments. Traditional pyrometallurgical and hydrometallurgical processing techniques, though widely used in the recovery of these REEs, have some environmental drawbacks; thus, new recovery approaches are under development. Here, Solvometallurgy has emerged as an environmentally friendly technology, and ionic liquids and deep eutectic solvents have turned out to be first-line chemicals to be used in the different unit operations employed in solvometallurgical processing, i.e., leaching, liquid–liquid extraction, ion exchange (adsorption), precipitation, and electrolysis. This manuscript reviews the most recent literature (2002–June 2023) concerning the use of ionic liquids and deep eutectic solvents in the recovery of REEs from various sources.

A fast and environment-friendly method for preparing nanopowders Mo through electro- desulfidation of MoS2 in LiCl melt

Fast–reaction rate production of Mo with energy-saving and environmental protection is important for industries. However, the present preparation of Mo by pyrometallurgical process in industry is challenging. Here we demonstrate a solution route through direct electro- desulfidation solid MoS2 at 973 K in LiCl melt with a fast and environment-friendly method. When the scan rate was 50 mV/s, the total reduction (0.5 mg MoS2 in the MCE.) time was less 16 s, and the peak current density was as high as 38 A/cm2 with reference to the geometric surface of the cavity (ca. 0.004 cm2)Nano molybdenum powder can be obtained on cathode and element sulfur on anode. The current efficiency was 95% and energy consumption was 1.02 kWh/kg- Mo. The details of the electro-desulfidation mechanism of solid MoS2 was also investigated by cyclic voltammetry, potentiostatic and constant voltage electrolysis. Accordingly, the electro-desulfidation mechanism may be speculated as followings: the intercalation compound containing Li+ (LixMoS2) was first generated and then LixMoS2 was reduced to nanometer Mo powder.

Hydrogen reduction process for zinc-bearing dust treatment: Reduction kinetic mechanism and microstructure transformations in a novel and environmentally friendly metallurgical technique

The iron and steel sector generates 80 million tons of zinc-containing dust annually, traditionally treated using carbon-based pyrometallurgical processes, which have significant drawbacks, including large carbon emissions, high energy consumption, and low production value. To address the above issues, a green hydrogen reduction method was developed for zinc-bearing dust treatment. This study examined the thermodynamics, reduction kinetics, and phase transformation during the process, revealing that at 800 °C, the hydrogen partial pressure for zinc oxide reduction is only 45.56 %. The direct reduction of zinc-containing dust pellets with hydrogen reveals that the limiting step of iron oxide and zinc reductions both are interfacial chemical reaction control at the reduction temperature of 800–950 °C, with an apparent activation energy of 16.42 kJ/mol and 71.39 kJ/mol. The kinetic mechanism indicates that reducing iron and zinc oxides is more accessible in a hydrogen reduction system, with lower apparent activation energies than carbothermal reduction. Consequently, hydrogen reduction offers a more efficient and environmentally friendly solution for treating zinc-bearing dust.

Antimony and gold substance flows analysis of pyrometallurgical process for antimony-gold concentrates

In this paper, substance flow analysis was used to analyze the production of antimony and gold in the pyrometallurgical process of complex antimony and gold concentrate. The comprehensive recovery and utilization of antimony and gold concentrate were studied in detail by establishing antimony and gold mass balance accounts and substance flow charts. The results showed that the resource efficiency of antimony and gold was 88.85% and 94.86%, respectively. The direct recovery of antimony in the blast furnace, gold smelting furnace, cupellation furnace and reverberatory furnace was 95.44%, 84.95%, 85.11% and 91.22%, respectively. The circular substance flow generated by the cupellation furnace accounted for 72.6% of the total circulation flow. One tonne of antimony accompanied 0.016 tonnes of antimony into water-quenched slag and 0.017 tonnes into the arsenic alkali slag. The proportion of gold entering antimony oxide, precious antimony, antimony matte and water-quenched slag in the blast furnace was 8.4%, 84%, 6.7% and 0.9%, respectively. The proportion of gold entering the gold-bearing products, antimony oxide and antimony slag in gold smelting furnace was 90.6%, 3.6% and 5.8%, respectively.

Extraction of niobium in one step from tin slag by NH4F‐HCl leaching process

AbstractNiobium and tantalum are generally found together in nature in ores such as columbite, tantalite, and pyrochlore. These ores can occasionally associate with cassiterite, the tin ore. The pyrometallurgical processes of cassiterite produces a slag that can contain Nb and Ta from the associated ores. Cassiterite processing for tin extraction has generated a considerable quantity of residue. This work aims to study the extraction of Nb from tin slag while leaving the Ta solid. The process of separation consists in one step by leaching using a combined solution of HCl‐NH4F. The slag was characterized by X‐ray fluorescence (EDXRF), atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectrometry (ICP‐OES), X‐ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and granulometric analysis. The effect of parameters of the leaching processes was investigated, such as the time of the process, HCl concentration, liquid‐to‐solid ratio, temperature, and salt‐to‐slag ratio. It was possible to recover 100% of Nb and 5% of Ta in liquor of leaching within 4 h, at 85°C, using an L:S ratio of 20:1, NH4F:slag ratio of 0.12 g, and HCl concentration equal to 9.79 mol/L.

Experiment and thermodynamic modelling of phase equilibria in PbO−“CuO0.5” and PbO−“CuO0.5”−“FeO1.5” slag systems with metal

The phase equilibria of the PbO−“CuO0.5” and PbO−“CuO0.5”−“FeO1.5” slag systems in equilibrium with solid metallic copper and/or liquid metallic lead−copper alloy were studied as part of the investigation of the 19-element PbO−ZnO−Cu2O−FeO−Fe2O3−CaO−SiO2−Al2O3−MgO−S−(As, Sn, Sb, Bi, Ag, Au, Ni, Cr, Co as minor elements) multicomponent slag/matte/metal/speiss system, supporting the operation and development of the existing and emerging pyrometallurgical processes. In the experimental portion of this study, samples underwent high temperature equilibration followed by quenching, after which the compositions in the liquid slag, solid oxide and metallic phases were directly measured by electron probe microanalysis (EPMA). Phase equilibria data on the massicot (PbO), spinel ((Fe, Cu)Fe2O4), cuprite (Cu2O), lead ferrite (Pb2+xFe2O5+x), magnetoplumbite (Pb1+xFe12−xO19−x), copper plumbite (Cu2PbO2), and delafossite (CuFeO2) primary phase fields were obtained between 688 and 1000 °C. A key finding of the experimental study of the PbO−“CuO0.5” subsystem was that the copper plumbite (Cu2PbO2) phase melted incongruently, contradicting previous studies that suggested it apparently decomposed below the binary eutectic temperature to form massicot (PbO) and cuprite (Cu2O). Based on the results of past and present experimental studies, a self-consistent set of thermodynamic model parameters describing all phases in the system was derived using the FactSage software package.

Antimony and arsenic substance flow analysis in antimony pyrometallurgical process

Substance flow analysis was applied to an antimony pyrometallurgical system. By taking antimony and arsenic as the objective elements, the mass balance and substance flow charts based on the production system were established, and evaluating indicators such as the direct recovery rate, waste recovery rate, and resource efficiency were set up. The results show that the resource efficiency of antimony is 89.21%, and the recovery rates of antimony in volatilization smelting, reduction smelting, and refining are 78.79%, 91.00%, 96.06%, respectively. At the same time, for 1 t of antimony produced, 11.94 kg of arsenic is carried into the smelting system. Arsenic is a major impurity element in the smelting process. The distribution behavior of arsenic in the main process was analyzed. Based on the substance flow analysis, some recommendations for improving the resource efficiency of antimony and cleaner production were proposed.

JOINT PROCESSING OF QUARTZ-LEUCOXENE CONCENTRATE AND BRUCITE CONTAINING WASTE FROM THE PRODUCTION OF REFRACTORY MATERIALS TO OBTAIN COMPLEX COAGULANTS

The volumes of large-tonnage mineral waste generation cause serious concern from the side of environmental supervision. Most of the mineral waste is a valuable secondary raw material, but the lack of integrated technologies for their processing significantly slows down their processing. As part of the work, an assessment was made of the possibility of joint processing of quartz-leucoxene concentrate (waste from the oil production process) and brucite-containing waste from the production of refractories. Joint pyrometallurgical processing of two waste products made it possible to obtain magnesium titanium, a valuable product for various industries. Hydrometallurgical processing of magnesium titanate made it possible to obtain a complex magnesium-titanium-containing coagulant, which showed extremely high efficiency in the process of treating wastewater with a high pH level (concrete mixing unit). The use of a complex reagent, in addition to increasing the cleaning efficiency (reducing residual concentrations of pollutants), made it possible to reduce reagent costs and intensify the processes of sedimentation and filtration of coagulation sludge (simplification of the instrumental scheme).

Recovery of Valuable Materials with the RecoDust Process

The RecoDust process is a pyrometallurgical process for treating steel mill dusts that cannot be recycled internally due to their zinc content, providing numerous benefits compared to conventional processes. State-of-the-art processes often face the problem of recycling only zinc, but not iron, which is frequently landfilled and withdrawn from a closed loop. Furthermore, these processes are also often limited to a specific zinc content in the feedstock. Within the described RecoDust smelting campaigns, basic oxygen converter dust with about 15 wt.% zinc was taken as feedstock. After high-temperature treatment of the input material, the RecoDust slag (RDS) has a zinc content of 0.4 wt.% and the crude zinc oxide (CZO) has a ZnO content of up to 80 wt.%. The RDS is suitable for use in the sinter plant as a secondary raw material. To investigate the influence of adding RDS to a common sintering mixture, sintering pot tests followed by RDI (reduction disintegration indices) tests were carried out. The influence of the admixture of RDS on the RDI values is not detectable. The CZO was fed into a soda extraction system for halogen removal. The halogen removal of this two-stage leaching was highly efficient with over 90% for chlorine.

Temperature and frequency dependencies of the permittivities of selected pyrometallurgical reaction mixtures

High temperatures are required in pyrometallurgical processes and consequently they are extremely energy intensive. Microwaves can offer several potential thermal energy efficiency advantages such as selective and/or rapid internal heating. The fundamental parameters which determine the interaction of microwaves with any given non-magnetic material are the real and the imaginary permittivities. In the current research, the permittivities of various mixtures of several pyrometallurgical raw materials plus carbonaceous reducing agents were determined as a function of both temperature and frequency, using the cavity perturbation technique. The raw materials investigated were an oolitic iron ore, an electric furnace dust and a chromite ore. As the temperature of a mixture increased, the permittivities began to increase rapidly, at temperatures lower than for the raw material alone. Subsequently, as the temperatures increased even further, the permittivities began to decrease and consequently peaks were typically observed in both the real and the imaginary permittivities. The changes in the permittivities of the mixtures were interpreted in terms of reduction reaction information available in the literature and also the amounts of the various species present as calculated by the Equilibrium Module of HSC Chemistry® 7.1. The initial rapid rise in the permittivities of the mixtures was attributed to the presence of the carbonaceous reducing agent, while the decrease was ascribed to the consumption of the carbonaceous reducing agent and also the reduction of metal oxides to metal. The permittivity data can be utilized to better understand the heating behaviour of the mixtures and also can be employed in numerical modelling.

Features of Copper Mobility During the Transition from Clinkers to an Aqueous Solution at the Belovsky Zinc Plant (Kemerovo Region)

Experimental data were presented on the mobility of copper during the transition from old wastes of pyrometallurgical processing of polymetallic ores (Belovsk zinc plant, Kemerovo region) into solution. Based on the data of percolation experiments, the article proposes the extraction method of copper with minimal environmental risks.

Temperature and frequency dependencies of the permittivities of ferroalloys and reaction mixtures

Ferroalloys, such as ferrochromium, ferromanganese and ferrosilicon are pyrometallurgically produced in energy intensive submerged arc furnaces. In turn, these materials can be used as reagents in a number of pyrometallurgical processes, where the energy requirements are typically supplied by electricity or by the combustion of hydrocarbons. Presently, there are significant incentives to develop more efficient processes, which utilize renewable energy. The electricity from these renewable sources can be converted into electromagnetic radiation, such as microwaves, which in turn can be used as a thermal energy source. The amount of energy absorbed from the electromagnetic field and the amount converted into heat are determined by the real and the imaginary permittivities, respectively. These permittivity results are needed for process development, in particular for numerical modelling. In this research, the permittivities of selected ferroalloys and reaction mixtures were determined as a function of temperature and frequency using the cavity perturbation technique. Also, the limitations of the cavity perturbation technique for these types of measurements are highlighted. In order to interpret the permittivity changes for the reaction mixtures, HSC Chemistry®7.1 was utilized to model the compositional changes as a function of temperature. The results indicate that microwaves are a potential heating source for ferroalloy production and also in processes which utilize ferroalloys as a reagent.

Current Trends in Spent Portable Lithium Battery Recycling.

This paper provides an overview of the current state of the field in spent portable lithium battery recycling at both the research and industrial scales. The possibilities of spent portable lithium battery processing involving pre-treatment (manual dismantling, discharging, thermal and mechanical-physical pre-treatment), pyrometallurgical processes (smelting, roasting), hydrometallurgical processes (leaching followed by recovery of metals from the leachates) and a combination of the above are described. The main metal-bearing component of interest is the active mass or cathode active material that is released and concentrated by mechanical-physical pre-treatment procedures. The metals of interest contained in the active mass include cobalt, lithium, manganese and nickel. In addition to these metals, aluminum, iron and other non-metallic materials, especially carbon, can also be obtained from the spent portable lithium batteries. The work describes a detailed analysis of the current state of research on spent lithium battery recycling. The paper presents the conditions, procedures, advantages and disadvantages of the techniques being developed. Moreover, a summary of existing industrial plants that are focused on spent lithium battery recycling is included in this paper.

Bioleaching Modeling-A Review.

The leaching of minerals is one of the main unit operations in the metal dissolution process, and in turn it is a process that generates fewer environmental liabilities compared to pyrometallurgical processes. As an alternative to conventional leaching methods, the use of microorganisms in mineral treatment processes has become widespread in recent decades, due to advantages such as the non-production of emissions or pollution, energy savings, low process costs, products compatible with the environment, and increases in the benefit of low-grade mining deposits. The purpose of this work is to introduce the theoretical foundations associated with modeling the process of bioleaching, mainly the modeling of mineral recovery rates. The different models are collected from models based on conventional leaching dynamics modeling, based on the shrinking core model, where the oxidation process is controlled by diffusion, chemically, or by film diffusion until bioleaching models based on statistical analysis are presented, such as the surface response methodology or the application of machine learning algorithms. Although bioleaching modeling (independent of modeling techniques) of industrial (or large-scale mined) minerals is a fairly developed area, bioleaching modeling applied to rare earth elements is a field with great growth potential in the coming years, as in general bioleaching has the potential to be a more sustainable and environmentally friendly mining method than traditional mining methods.