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Address to low recovery rates of gallium in the process of zinc hydrometallurgy by two-stage countercurrent oxygen pressure leaching in a smelter, XRD, SEM-EDS and ICP-AES were used to analyze the solutions and residues phases at each stage of the process, and the mechanism of the influence of pre-neutralization and zinc powder replacement on the low gallium recovery was investigated. The results show that the co-precipitation of gallium with jarosite or plumbojarosite due to the low acidity during the pre-neutralization of the primary leaching solution is the cause of gallium loss. In the process of zinc powder replacement, gallium cannot be precipitated completely by increasing pH value only by zinc powder. It is suggested that the acidly of the end point of the preneutralization is controlled to 6 g/L, the reaction time is one hour, and the reaction temperature is 85 °C to avoid gallium loss during the preneutralization process. In the replacement stage, the method of first neutralization and then replacement is adopted: 7 g/L high-quality zinc oxide is used for neutralization reaction for one hour, and then 3 g/L zinc powder Is added for reaction for one hour at 85 °C. After optimization, the precipitatlon rate of gallium can reach 100%. [ABSTRACT FROM AUTHOR]

Pressure hydrometallurgy is one of the special metallurgical technologies, which is widely used in the separation, extraction, metal reduction and mineral synthesis of alumina, laterite nickel ore, sphalerite and gold ore. The development history of pressurized hydrometallurgy technology in China for more than 60 years shows that the production process, technical equipment and scale have reached the world advanced level. In the face of the increasingly fierce competition in the domestic and foreign non-ferrous metal market, energy conservation, emission reduction and environmental protection awareness, as well as the more stringent technical requirements of the production process, the pressure hydrometallurgy technology has increasingly shown its inherent technical advantages in the efficient and clean utilization of complex and low-grade refractory minerals, the pressurized hydrosynthesis and preparation, pressurized hydrohydrogen reduction and low-carbon metallurgy. In this paper, the development and characteristics of pressure hydrometallurgy technology are described, with emphasis on the research progress of clean production of alumina pressure hydrometallurgy, oxygen pressure leaching of sulfide ore and pressure hydrometallurgy of vanadium slag. Finally, the development prospect and direction of pressure hydrometallurgy technology in the future are prospected. [ABSTRACT FROM AUTHOR]

The recovery of spent lithium‐ion batteries by traditional acid leaching is limited by serious pollution, complicated technology, and the low purity of Li2CO3. To address the problems of the traditional acid leaching process and increasing demand for decarbonization, a technique for the selective carbonation leaching of Li and the recovery of battery‐grade Li2CO3 by a simple concentration precipitation process without acids or bases was developed. The coupling of CO2 and reducing agents could effectively promote the precipitation of MCO3 (M=Ni/Co/Mn) and the selective leaching of Li by decreasing the reducing capability needed for transition metals and decreasing the pH of the solution. The optimal selective leaching process of Li was obtained under 1 MPa CO2 with 20 g/L Na2S2O3 at an L/S ratio of 30 mL/g for 1.5 h. FT‐IR, XRD, ICP‐MS and other methods were used to reveal the multiphase interfacial reaction mechanism of the carbonation reduction of layered cathode materials, which indicated that the reducing agent Na2S2O3 could promote lattice distortion of the cathode materials and effective separation of Li. In summary, a green and economical method for the selective recovery of battery‐grade Li2CO3 using a one‐step method of CO2 carbonation recovery in a near‐neutral environment was proposed. [ABSTRACT FROM AUTHOR]

The growing demand for valuable metals in recent decades has heightened the economic significance of extracting them from dilute solutions. This research carefully assesses the extraction efficiency of the air-assisted solvent extraction (AASX) process for effectively recovering copper from industrial dilute solutions, such as the raffinate of the solvent extraction (SX) plant and heap leach solutions. The results clearly showed that increasing the frother dosage to 50 mg/L improved the Cu extraction from 83.5% to 90.2%, but increasing the frother dosage beyond 50 mg/L did not change this response significantly. Although varying the extractant concentration and silicone oil dosage in the studied range did not affect Cu extraction, it noticeably led to an increase in the barrier metals recovery. Furthermore, a nine-step AASX system was applied to comprehensively evaluate the extraction efficiency of Cu from dilute heap leach solution. Moreover, an impressive 95.1% of Cu recovery (from a solution containing 890 mg/L Cu, 12.32 g/L Fe, 2.64 g/L Zn, and 4.1 g/L Mn) was achieved with selectivity ratios of 149.6, 153.0, and 93.5, for Cu/Fe, Cu/Zn, Cu/Mn, respectively. It could be concluded that the AASX process is an efficient and promising method for extracting Cu from industrial dilute solutions derived from secondary resources, low-grade ores, and acid mine drainages. [ABSTRACT FROM AUTHOR]

Recycling processes of lithium-ion batteries used in electric and hybrid vehicles are widely studied today. To perform such recycling routes, it is necessary to know the composition of these batteries and their components. In this work, three pouch and three cylindrical LIBs were discharged, dismantled, and characterized, having their compositions known and quantified. The dismantling was performed using scissors, pliers, and a precision cutter equipment. The organic liquid electrolyte was quantified via mass loss after it evaporated at 60 °C for 24 h. The separators were analyzed using Fourier-transform infrared spectroscopy (FTIR), and the cathode and anode active materials were analyzed using a scanning electronic microscope coupled to an energy-dispersive spectroscope (SEM-EDS), X-ray diffraction (XDR), and energy-dispersive X-ray fluorescence spectrometry (EDXRF). All LIBs were identified by type (NCA, NMC 442, NMC 811, LCO, and two LFP batteries), and a preliminary economic evaluation was conducted to understand their potential economic value (in USD/t). Both results (characterization and preliminary economic evaluation) were considered to discuss the perspective of recycling towards a circular economy for end-of-life LIBs. [ABSTRACT FROM AUTHOR]

Bioleaching, a process catalyzed by acidophilic microorganisms, offers a sustainable approach to metal extraction from sulfide minerals. Chalcopyrite, the world's most abundant copper sulfide, presents challenges due to surface passivation limiting its bioleaching efficiency. Also, indigenous species and microbial communities may present high copper extraction rates and offer new possibilities for application in bioleaching processes. This study examines the bioleaching potential of microbial isolates and communities obtained from Amolanas Mine in Chile. Samples were collected, cultivated, and identified by Sanger sequencing. The bioleaching potential and biofilm formation of isolates and enrichments were evaluated on pyrite and chalcopyrite. The results show the isolation of nine Leptospirillum and two Acidithiobacillus strains. The bioleaching experiments demonstrated good copper bioleaching potentials of the Leptospirillum I2CS27 strain and EICA consortium (composed mainly of Leptospirillum ferriphilum, Acidiphilium sp., and Sulfobacillus thermosulfidooxidans), with 11% and 25% copper recovery rates, respectively. Microbial attachment to the surface mineral was not mandatory for increasing the bioleaching rates. Our findings underscore the importance of indigenous microbial communities in enhancing copper bioleaching efficiency. [ABSTRACT FROM AUTHOR]

Nickel is a strategic element whose production and consumption in over a decade has increased to over 39% and 71%, respectively. Generally, due to their complex mineralogy, laterites, the current attractive source of Ni, are subjected to hydrometallurgy and pyrometallurgy techniques without enrichment in order to extract Ni. Therefore, numerous investigations in vogue on laterite enrichment performed spanning from 1964 to date were reviewed in this article, and the future directions were proposed through critical synthesis. The possibilities of obtaining both higher recoveries and increase in grade for Ni were noticed using selective comminution-classification method followed by flocculation-flotation strategy. Hence, in order to improve on the reported Ni yields from selective comminution-classification process, one of the ways could be to subject the ore to a multi-stage selective comminution-classification method followed by subjecting the obtained concentrate to flocculation-flotation technique. Therefore, the findings of this investigation would aid in upscaling the production to meet the demand. Properties of goethite and serpentine were explored. Physical and flotation methods for laterite enrichment were reviewed. Future directions for laterite beneficiation were proposed. [ABSTRACT FROM AUTHOR]

Recycling materials from end-of-life devices and products is becoming increasingly a fundamental activity for the sustainable development of nations. With the return from the market of immense quantities of photovoltaic panels at the end of their life, it is essential to foresee processes for recovering and valorizing all the raw materials present in them to avoid wasting important flows of raw materials. This research introduces a novel process aimed at the recovery of silver and silicon from end-of-life photovoltaic panels. The leaching efficiency and kinetics of ground cake powder in sulfuric acid, ferric sulfate, and thiourea were investigated in the leaching system. In particular, the influences of significant parameters, including particle size, leaching temperature, and stirring rate, on the extraction kinetics were analyzed using the shrinking core model. The results showed silver dissolving mechanisms, in which more than 90% of silver recovery at 60 min of reaction time and 99% at 120 min was achieved (120 rpm, 53–125 µm, and 40 °C). The significant effect of the leaching temperature suggests that the process is under the control of the chemical reaction. Moreover, these results were confirmed by the regression analysis of the experimental data with the shrinking core model. It can be concluded that this newly proposed process, called Gold-REC1, allows the recovery of Ag and Si (solid residue from the process) with extremely high yields and rapid kinetics. The obtained results can provide fundamental data for developing end-of-life photovoltaic recycling on an industrial scale. [ABSTRACT FROM AUTHOR]

Hydrometallurgy is a novel metallurgical methodology that employs hydrogen as a reducing agent, thereby facilitating efficient, low energy consumption, and eco-friendly metal smelting processes. This study establishes a new fluidized bed hydrogen direction reduction system, which encompasses hydrogen production by water electrolysis, hydrogen direct reduction iron, waste heat utilization, and hydrogen recovery with Aspen Plus. The impact of the hydro-to-iron ratio and reaction temperature on the iron reduction and the energy and exergy efficiencies of the system is investigated. The results indicate that, the higher the hydro-to-iron ratio or reaction temperature, the higher the reduction rate. The energy efficiency of the system exhibits a non-linear trend with respect to temperature and the exergy efficiency demonstrates an overall increase with temperature or the hydro-to-iron ratio. • A new fluidized bed hydrogen reduction system with hydrogen recycling is established. • Increasing temperature and hydro-to-iron ratio enhances iron oxide reduction by hydrogen. • The energy efficiency of the system shows a non-linear trend with temperature. • The exergy efficiency increases with temperature or the hydro-to-iron ratio. [ABSTRACT FROM AUTHOR]

With the increasing usage rates of lithium ion batteries used in energy storage, the management of the resulting waste has also increasingly important. The short lifespan of lithium ion batteries and the precious metals they contain require careful management of these wastes from a technical, environmental and economic perspective. Therefore, in the context of the recovery of precious metals such as cobalt from waste lithium ion batteries, in this article, literature studies on the recovery of cobalt from commonly sed types of lithium ion batteries in the form of Nickel Manganese Cobalt and Lithium Cobalt Oxide have been evaluated. The literature review shows that the most commonly used methods are hydrometallurgical, pyrometallurgical and direct recovery methods. As the demand for lithium ion batteries increases in the coming years, the need to develop and optimize innovative methos for cobalt recovery will become even more important in achieving sustainability goals within energy storage systems. [ABSTRACT FROM AUTHOR]

The present paper describes the technological solution for obtaining Cu, Zn, Pb, and Ag from jarosite waste raw material, with its simultaneous separation from In and Fe. By roasting at low temperatures, iron was transformed from the Fe2(SO4)3 form into Fe2O3, which is insoluble in water and slightly soluble in acid. Copper sulfate and zinc sulfate are present in jarosite as sulfates. During temperature roasting, the copper and zinc were still in the form of CuSO4 and ZnSO4, i.e., they were easily dissolved in water. This procedure led to good selectivity of Cu and Zn compared to Fe. After water leaching, PbSO4 and Ag2SO4 remained in the solid residue. By treating jarosite with a content of 0.7% Cu, 5.39% Zn, and 5.68% Pb, products of commercial quality were obtained. By roasting jarosite in an electric furnace and leaching the roasted sample in water, leaching degrees of 91.07%, 91.97%, and 9.60% were obtained for Cu, Zn, and Fe, respectively. Using 1 M NaOH in the leaching solution, 99.93% Fe was precipitated to pH = 4. Cu in the form of CuSO4 was further treated by cementation with Zn, after which cement copper was obtained as a commercial product. Zn in the form of ZnSO4 was further treated by precipitation with Na2CO3 to obtain ZnCO3 concentrate of commercial grade. The total recovery of Pb and Ag, which were treated by chloride leaching, was 96.05% and 87.5%, respectively. The resulting NaPbCl3 solution was further treated with Na2CO3 solution, whereby PbCO3 was obtained as a commercial product. The produced PbCO3 could be further subjected to roasting to obtain soluble PbO. In these investigations, PbCO3 was smelted where a Pb anode was obtained; this was electrolytically refined to a Pb cathode. The proposed process does not pollute the environment with As and Cd. [ABSTRACT FROM AUTHOR]

Samarium-cobalt (SmCo) magnets, comprised of rare earth elements (REE), and cobalt (Co) are widely employed in diverse sectors such as aerospace, medical, defense, automotive, and more due to their unique properties such as outstanding high-temperature resistance, superior corrosion resistance, a higher Curie temperature, and high energy density. REE and Co are on the critical metals list for many years, along with increased production costs and challenges. With the increasing amount of waste SmCo, the recycling of these magnets has gained importance. This study investigates the recycling of SmCo magnet scraps through sulfation, selective oxidation, and water leaching. The effect of experimental parameters, such as powder/acid concentration, selective oxidation temperature, selective oxidation time, solid/liquid ratio and leaching time for water leaching are studied in detail. The optimal parameters are determined: 800°C selective oxidation temperature, 1-h selective oxidation time, 1/3 g/ml magnet: acid ratio, 2-h water leaching time and 1/20 water leaching s/l ratio. Under the optimum conditions the extraction efficiency of Sm reached approximately 65%, The solubility of Fe, Co, and Cu metals in the solution is negligible. [ABSTRACT FROM AUTHOR]

Rare metal gallium is classified as a strategic material because of continued high demand, uncertain supply, and low reserves. Corundum flue dust (CFD) is generated during bauxite smelting to produce brown corundum. Gallium (Ga), Zinc (Zn), and potassium in the bauxite could be enriched with CFD through this process, so CFD is regarded as one of the potential sources of Ga and Zn. A novel that utilizes ultrasound to enhance the H2SO4 leaching efficiency of Ga and Zn from CFD was developed from CFD. The effects of ultrasound power, leaching time, sulfuric acid concentration, and leaching temperature on the leaching behavior of Ga and Zn were studied, and the corresponding kinetics model was established. It was found that the maximum Ga and Zn leaching efficiencies of 81.22% and 96.72% were obtained at optimum leaching conditions: the leaching temperature of 90°C, the leaching time of 60 min, 3 M H2SO4, the solid-to-liquid ratio of 1:5 (g/mL), and the ultrasound power of 750 W. In all cases, the leaching effect of Zn is not significantly improved by ultrasonic treatment, but the leaching efficiency of Ga has a positive effect (more than an 18% increase). Kinetic analysis shows that the leaching process of Ga and Zn were controlled by chemical reaction and diffusion, respectively. The apparent activation energy values are 20.39 kJ/mol for Ga and 13.44 kJ/mol for Zn. The characterization of the leaching residues reveals that the ultrasound effected to enable the whole block to be fractured or dispersed into fragments, accelerating the penetration of H2SO4 into the pores and cracks at the solid, which further prompts the dissolution of the encapsulated gallium and achieves the conspicuous improvement to Ga leaching efficiency. [ABSTRACT FROM AUTHOR]

In response to the problem of additive zinc concentrate consumption and inefficient reduction of ferric ion (Fe3+) in the acid-leaching solution of zinc hydrometallurgy when employing zinc sulfide concentrate, various parameters were examined. These included particle size, temperature, addition coefficient of the concentrate, and sulfuric acid concentration, all aimed at enhancing the rate of Fe3+ reduction. The results indicated that increasing the temperature from 80 to 120°C enhanced the Fe3+ reduction rate from 93.3 to 98%, reducing the time from 180 to 60 min. Furthermore, enlarging the particle size of the concentrate from below − 58/+ 48 μm to − 246/+ 150 μm, lowering the Fe3+ concentration in the reduction solution to < 0.5 g/L, and decreasing the addition coefficient from 1.8 to 1.5 further enhanced the reduction process. Additionally, employing a pressure process to increase the reduction temperature proved to be an effective strategy for enhancing the utilization rate of the zinc sulfide concentrates and the Fe3+ reduction rate, thereby reducing the amount of reduction residue and facilitating its subsequent treatment. [ABSTRACT FROM AUTHOR]

In recent years, the increasing demand and rising prices of rare earth elements (REEs), along with their attendant supply risk (about 95% of these elements are supplied by China), have led the European Commission to consider REEs as critical raw materials. Developing and optimizing processes for recovering REEs from secondary sources such as NdFeB magnets is fundamental in this context. A novel method to recover REEs by leaching with citric acid and subsequently separating these elements using the solvent extraction method has been introduced. Therefore, this research investigates the leaching efficiency of REEs, Fe, and B from NdFeB magnets. A full factorial design, with 18 experimental setups, was conducted to optimize the citric acid concentration (1–3 mol/L), leaching time (1–3 h), and solid–liquid ratio (5–10%wt./vol.). All tests were carried out at room temperature and 150 rpm. Different optimizations (response surface methodology (RSM) and artificial neural network (ANN) analysis) are used to maximize the REEs' leaching efficiency. RSM resulted in a maximum extraction yield of total rare earth elements (TREEs) of about 89% in the investigated experimental plan. This result is similar to that for ANN analysis (about 86%), but more accurate than that for RSM. In fact, for the ANN, an overall R-value higher than 0.99 was obtained. This result indicates that the developed ANN can be used as an accurate model for estimating the leaching efficiencies of REEs from NdFeB magnets. [ABSTRACT FROM AUTHOR]

The characteristics, industrial application status and research progress of hydrometallurgy for low grade laterite nickle ore by reduction roasting--normal pressure ammonia leaching and high-pressure acid leaching (HPAL), as well as the development of three generations of HPAL technology are summarized. The nickle-cobalt precipitation and enrichment technology and the application are introduced. The processes advantages and disadvantages of the H2S precipitation, MgO precipitation, direct NaOH precipitation are analyzed. The effectiveness of new precipitation process with alkali conversion and crystal seed activation has been explored. The development prospect of laterite nickel hydrometallurgical process is also prospected. [ABSTRACT FROM AUTHOR]

The surge in mining and mineral processing to meet metal demand has led to accumulation of mining by-products like tailings, waste rocks, and acid mine drainage, containing high iron, copper, nickel, and zinc concentrations. These residues pose environmental threats. The concept of technospheric mining aims to repurpose these wastes for beneficial uses, reducing disposal and ecological impact while benefiting stakeholders. Within this context, the present investigation focuses on the discriminative retrieval of copper and nickel from mine tailings characterized by elevated iron content. This is achieved through formulation of an energy-efficient technique designed to surmount the challenge of iron co-extraction during hydrometallurgical processes aimed at extracting and recuperating metal values from intricate phases. The proposed method entails the amalgamation of mine tailings and solid NH4Cl in a stoichiometric ratio of 1:2, followed by roasting at 300 °C for a span of 1 h. Application of chloridized roasting orchestrates the transformation of copper and nickel into soluble metal chlorides, while concurrently inducing conversion of iron into a stable iron oxide state. Subsequent stages encompass the separation of copper and nickel from the water leach liquor, achieved through solvent extraction techniques utilizing LIX84I and Cyanex 272 as extractants. Rigorous characterization efforts, employing techniques such as X-ray Diffraction (XRD) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), are undertaken to elucidate the attributes of the raw material and solid residues. Remarkably, the comprehensive isolation of copper, nickel, and iron is realized without generation of any effluents, ensuring preservation of environmental equilibrium.

The recycling of used lithium-ion batteries has become a growing concern. As a large number of rare metal elements are present in waste lithium-ion batteries, recycling them can significantly improve resource utilization and reduce the material cost of battery production. The process of recycling used lithium-ion batteries involves three main technology parts: pretreatment, material recovery, and cathode material recycling. Pretreatment includes discharge treatment, uniform crushing, and removing impurities. Material-recovery technology mainly involves traditional pyrometallurgical and hydrometallurgical technologies, as well as the developing biometallurgy technology. Analysis of existing data shows that pretreatment technology is crucial for the recycling of used lithium-ion batteries. Hydrometallurgical technology and pyro-hydrometallurgical technology are expected to be the most suitable industrialization technology paths in the future, with biometallurgical technology and direct recycling technology providing a low-pollution development direction. This article summarizes the different pretreatment techniques and valuable metal-recovery pathways. The advantages and disadvantages of each method were evaluated. The economic costs, environmental benefits, and degree of industrialization of each method were assessed. The possible development directions of various methods are summarized to provide reference for future research. [ABSTRACT FROM AUTHOR]

This study analyzes the key processes of hydrometallurgical technology, constructs an optimization con- trol model, and improves the particle swarm algorithm using adaptive inertia weight and simulated annealing operators to achieve optimization control of hydrometallurgical technology. Simulation test results show that in the test on the A wind farm optimization dataset, the AIWSAO - PSO algorithm stabilizes after 225 iterations with a fitness value of 0. 165. At 100 iterations, the algorithm's root mean square error, mean absolute error, and relative standard deviation (RSD) are 0.008 0, 0.004 5, and 0.971%, respectively. In the optimization control model for hydrometallurgical technology, the obtained comprehensive benefit value is 1.9 x 105 yuan/h, with an absolute error of about 0. 1 x 104 yuan/h from the target expected value. This achieves the optimization control of the hydrometallurgical process and provides technical support for similar optimization control applications. [ABSTRACT FROM AUTHOR]

This review examines the technological surveillance of photovoltaic panel recycling through a bibliometric study of articles and patents. The analysis considered the number of articles and patents published per year, per country, and, in the case of patents, per applicant. This analysis revealed that panel recycling is an increasingly prominent research area. However, the number of patents filed annually has varied in recent years, averaging fewer than 200 per year. The state-of-the-art review identified three main types of treatment for photovoltaic panel recycling: mechanical, chemical, and thermal. Among these, mechanical treatment serves as a preliminary stage before the recovery of valuable elements, which is achieved through chemical or thermal processes. The articles reviewed cover a range of processes, including hydrometallurgical and pyrometallurgical methods, and explore various classification processes, solvents, and oxidizing agents. In contrast, patents predominantly focus on pyrometallurgical processes. This analysis is supplemented by a survey of market-ready technologies, many of which include stages such as size reduction or delamination followed by pyrometallurgical processes. Additionally, the review highlights the collection processes implemented by some companies, noting that the volume of panels considered waste is currently insufficient to maintain a continuous and year-round operational process. This study identifies key challenges such as (i) reducing solar panel size due to the EVA polymer complicating conventional machinery use, (ii) high process costs from the need for high temperatures and costly additives, (iii) the environmental impact of thermal treatments with high energy consumption and air pollution, and (iv) the necessity for environmentally friendly solvents in hydrometallurgical treatments to reduce contamination during recycling. Future directions include developing specific machinery for panel size reduction, either creating or modifying a polymer to replace EVA for easier treatment, adopting hydrometallurgical treatments with green solvents proven effective in recycling minerals and electronic waste, and addressing the lack of detailed information on industrial processes to make more precise recommendations. [ABSTRACT FROM AUTHOR]

The re-dissolution of unstable iron oxides during the low-temperature hematite process significantly increases the iron ions concentration in solution after iron removal in zinc hydrometallurgy. The reason for the re-dissolution of precipitated hematite was determined through simulated iron removal experiments in an autoclave. It was caused by e.g., weak acid solubility resistance in high acidity and the poor crystallinity of hematite. In order to solve the problem of re-dissolution of hematite precipitated in a short time, three improving methods, namely increasing the reaction temperature, extending the reaction time in the autoclave, and reducing the acidity of hematite process, have been systematically studied. Increasing the reaction temperature is not economical from the perspective of industrial production, and extending the reaction time does not meet the original intention of the zinc smelter to increase production capacity. Although zinc sulfide concentrate as a neutralizing agent can increase the pH of the slurry, the hematite produced does not have the potential for sales. When 12 g/L zinc calcine was added, the residual Fe concentration in solution after iron removal within 90 min can be controlled below 1 g/L, and high-grade hematite with Fe, Zn, and S contents of 56.62%, 2.09%, and 2.78% can be produced. [ABSTRACT FROM AUTHOR]

BACKGROUND: Batteries play a vital role in meeting global energy needs. When their life cycle concludes, improperly discarded spent batteries can pose environmental risks primarily due to their metal content. In this sense, the recycling of metals contained in spent batteries could mean a huge advantage if they are extracted and purified using environmentally friendly processes. RESULTS: In this study, the recovery of potassium (K), zinc (Zn) and manganese (Mn) from alkaline batteries was performed using a hydrometallurgical process consisting of neutral, acid and acid reductive leaching steps at room temperature and atmospheric pressure to extract K, Zn and Mn. In the neutral leaching step, 76.8 ± 3.4 (wt. %) of the K present in the spent batteries was extracted. Thus, in the acid leaching step, 90.9 ± 0.1 (wt. %) of the initial Zn and 36.7 ± 0.4 (wt. %) of the initial Mn was extracted using sulfuric acid (H2SO4) 2 M. In a subsequent acid reductive leaching step using H2SO4 2 M and oxygen peroxide (H2O2) 0.8 M as reducing agent, 8.7 ± 0.1 (wt. %) of the initial Zn and up to 49.4 ± 0.2 (wt. %) of the initial Mn were extracted. CONCLUSION: The three‐unit process led to an overall extraction of 99.6 ± 0.3 (wt. %) of Zn and 86.1 ± 0.1 (wt. %) of Mn. Regarding the latter step, the extraction was not 100% because Mn complexes which are nearly insoluble were generated. This shows that extraction of valuable minerals from industrial residues is possible by hydrometallurgical processes. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The purpose of this work is to obtain the optimum conditions for leaching the zinc contained in an industrial lead smelting slag. In this type of slag, zinc oxide, sulfide, and ferrite are contained. Zinc extraction from these compounds consists of using a single aqueous medium, where oxidant alkaline leaching with NaOH and NaClO was used. The parameters evaluated during the experiment were as follows: percentage of solids, NaOH/NaClO ratio, and temperature. The maximum amount of recovered Zn obtained during the leaching was 58%. This percentage was achieved by using the following optimal conditions: temperature of 60 °C, 0.22 of NaOH/NaClO ratio, 10% of solids, and a reaction time of 40 min. The calculated values of activation energy confirmed that the rate-limiting step of the reaction using the decreasing particle model is diffusion. The maximum percentage of zinc obtained could only have been achieved if the zinc oxide and part of the zinc sulfide (both present in almost equal proportions in the sample) were leached into the alkaline aqueous medium in the presence of NaClO. [ABSTRACT FROM AUTHOR]

The use of alumina-containing nepheline raw materials as an alternative source of alumina is relevant in the context of the limited bauxite reserves in Kazakhstan. Nepheline processing can result in products such as alumina, sodium and potassium salts, silicate products and rare metals. In terms of economic value, alumina is the most important. This article considers an advanced technology for nepheline processing for the extraction of alumina that is first purified from potassium. The application of calcium sulphate and calcium oxide as additives to the nepheline raw materials is studied. The optimal conditions for two-stage leaching with calcium additives in the form of calcium sulphate and calcium hydroxide are determined. [ABSTRACT FROM AUTHOR]

The economic advantages of H2SO4 make it the acid of choice for the hydrometallurgical treatment of waste lithium-ion batteries (LIBs). However, to facilitate the full dissolution of the higher valency metal oxides present in the cathode black mass, a suitable reducing agent is required. Herein, the application of industrial black liquor (BL) obtained from the Kraft pulping for papermaking is investigated as a renewable reducing agent for the enhanced leaching of transition metals from LIB powder with H2SO4. The addition of acidified BL to H2SO4 significantly improved the leaching efficiency for a range of LIB cathode chemistries, with the strongest effect observed for manganese-rich active material. Focusing on NMC111 (LiMnxCoyNizO2) material, a linear correlation between the BL concentration and the leaching yield of Mn was obtained, with the best overall leaching efficiencies being achieved for 2.0 molL-1 H2SO4 and 50 vol% of BL at 353 K. A quasi-total degradation of oxygenated and aromatic groups from the BL during NMC111 dissolution was observed after leaching, suggesting that these chemical groups are essential for LIB reduction. Finally, the leached transition metals could be easily recovered by pH adjustment and oxalic acid addition, closing the resource loop and fostering resource efficiency. [ABSTRACT FROM AUTHOR]

The aim of lithium-ion battery (LiB) recyclers is to create a closed-loop process to recover and reuse all the material as secondary sources of material to manufacture new batteries. Global LiB recycling companies apply pyrometallurgy, hydrometallurgy, or direct recycling to meet this goal. Pyrometallurgy is very energy intensive, but hydrometallurgy requires a pretreatment process and a new version of direct recycling that shows more promise for automation would also require pretreatment. Currently, recycling companies appear to favor hydrometallurgy. This review summarizes the current state of development of the pretreatment process involving battery discharging and mechanical treatment series from the literature and its application in the industry, with particular attention on Asia Pacific recyclers. The key pretreatment steps of battery discharging and mechanical treatment are the focus of this review, but pretreatment of the black mass containing cathode material prior to leaching is also included. Discharging is important to reduce the risk of fire during mechanical treatment. An interesting finding is that despite promising laboratory results, there has been no reported commercial application of battery discharging using the submersion method in an electrolyte solution. An efficient mechanical treatment of discharged batteries is essential to remove the impurities which could adversely impact the subsequent LiB processing. Research into mechanical treatment should also include a method to evaluate the liberation of material. This review has highlighted a new potential flowchart for recycling of various cathode types of LiBs. [ABSTRACT FROM AUTHOR]

Hyperspectral imaging systems (HSIs) are becoming widespread in the mining industry for mineral classification. The spectral features detectable from near infrared to long-wave infrared make HSIs a potentially efficient tool for exploration, clay mapping, and leach pad modeling. However, the redundancy of hyperspectral data makes the analysis of hyperspectral images complicated and slow. Many researchers have proposed different algorithms and strategies to speed up processing and increase accuracy. These procedures rely on endmember extraction as one of the critical steps. However, no one has tested whether endmember extraction actually improves accuracy under all circumstances. Eliminating endmember extraction, if possible, would speed up the analysis of hyperspectral data. This study tested whether endmember extraction improves the accuracy and efficiency of mapping materials at leach pads, which are among the most complicated situations in mining environments. We compared the accuracy of abundance maps produced with fully constrained least squares (FCLS) (a) with endmember extraction by N-FINDR and (b) without endmember extraction, using a spectral library instead. The results from endmember extraction showed lower accuracy than the results from using a spectral library, probably because the spectral data were noisy and the scanned materials were mixtures. The application of FCLS to hyperspectral images provides useful information for metallurgists. The abundance maps showed that kaolinite, muscovite, and precipitation (hexahydrite and pickeringite) were the dominant minerals on the leach pad. The abundance maps of pipes and precipitation can be used to monitor leaching conditions. Lixiviant ponds mapped out in the abundance map of water can indicate saturation. This technique can also detect organic leakage and agglomeration effectiveness, but it will need different wavelength ranges and more future study. This paper also suggests best practices for using hyperspectral imaging systems to map leach pads. [ABSTRACT FROM AUTHOR]

Aluminum is produced from its primary bauxite ore through the Bayer process. Although Al is important nowadays in the development of humanity, its production leads to the generation of a huge amount of waste, called red mud. Globally, the estimation of the stock of red mud is about 4 billion tons, with about 10 million tons located in Turkey. The presence of rare-earth elements (REEs) in crucial materials such as red mud makes it a major source of these elements. A number of methods have been developed for treating red mud, which are employed globally to recover valuable products. The application of a suitable method for REE extraction from red mud is a way to overcome the supply risk, contributing to reducing the environmental issues linked to red mud pollution. The current review summarizes the research on red mud processing and examines the viability of recovering REEs from red mud sustainably, utilizing hydrometallurgy and biohydrometallurgy. [ABSTRACT FROM AUTHOR]

The usage of copper (Cu) ores containing low or no arsenic (As) has reduced, and Cu ores containing high levels of As have emerged as vital mineral resources for Cu extraction and processing. The quality of the Cu ores has decreased from 1.6% to approximately 1.0%. The proportion of As to Cu in 15% of Cu resources currently reaches 1:5. However, during the extraction and processing of Cu ores, As presents significant environmental harm. Hence, safely and effectively removing As is paramount in Cu smelting and processing, holding substantial importance in fostering environmentally sustainable practices within the Cu extraction and processing industry. This article consolidates the resource distribution of As-containing Cu (ACC) ores, comprehensively and systematically evaluates the present advancements in extracting techniques for these minerals, and identifies the challenges inherent in pyrometallurgical and wet processes for treating ACC deposits. Pyrometallurgy is a simple primary roasting technique and has widespread applicability in the treatment of various ACC minerals. Its disadvantages are the emission of exhaust gas and the high treatment costs associated with it. The wet arsenic removal method boasts advantages including minimal air pollution and a high resource recovery rate, significantly aiding in Cu concentrate recovery; its major drawback is the production of As-containing wastewater. The hydrometallurgical removal of As from ACC mines involves extracting As through leaching. Recently, biometallurgy has presented innovative solutions using specialized microorganisms to bioleach or bioabsorb As, but large-scale industrial applications still lack specific practical implementation. This review explores the underlying causes of the challenges encountered in processing ACC minerals. Additionally, it highlights pyrometallurgical roasting coupled with high-temperature filtration as a pivotal advancement in the extraction and processing of ACC ores. [ABSTRACT FROM AUTHOR]

In this work, a facile hydrometallurgical approach combined with heat treatment has been adopted to recycle spent graphite from retired lithium‐ion battery cells. Graphite regenerated with 18 M H2SO4 leaching leads to a high specific surface area, significant porosity and small crystallite size. The regenerated graphite has been infiltrated with sulfur under solvothermal conditions at 160 °C. The sample containing 68 wt % of sulfur recovers a capacity of 224 mAh/g after 100 cycles. Furthermore, the electrode with a higher sulfur content of 84 wt %, recuperates the specific discharging capacity of 207 mAh/g after 100 cycles. After the initial fading during the first 5–10 cycles, the cathodes based on regenerated graphite demonstrate stable cycling behavior. This research not only offers an accessible and scalable method for regenerating graphite from spent LIBs but also demonstrates a new application of the regenerated graphite in LSBs, showcasing outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]

Notable increases in metal consumption and declining ore grades in recent decades have stressed the significance of dilute solutions as secondary sources of valuable metals. Moreover, environmental considerations and the imperative of sustainable development have further emphasized their treatment. Therefore, finding an efficient solution for separating metals from dilute solutions has attracted the attention of numerous researchers. This paper reviews the purification processes of dilute solutions and highlights key achievements of published research works. Although this study focuses on evaluating the efficiency of recently developed aqueous-phase purification methods, such as immobilized ligands, ionic liquids, and air-assisted solvent extraction, the application of conventional processes to treat these solutions, such as solvent extraction, ion exchange, membranes, chemical precipitation, and adsorption are also briefly outlined. To provide a comprehensive assessment, more than 200 research articles were reviewed, and their key findings are stated in this study. This research contributes to the advancement of knowledge of metal recovery from dilute solutions and sheds light on the dynamic evolution of this field. [ABSTRACT FROM AUTHOR]

Electronic waste grows globally at a rate of 5% annually, which makes electronic waste recycling (WEEE recycling) an urgent task aimed at achieving (i) environmental protection and (ii) the preservation of mineral resources through the re-introduction of strategic metals into the market. As it turns out, WEEE recycling produces further waste, called WEEE secondary waste, which still contains valuable metals such as gold, silver, and copper. This study assessed the economic viability of recovering these metals and identified the most promising targets and approaches. WEEE secondary waste produced at a plant in southern Europe was sampled and examined for this purpose. The study methods included an ANOVA (analysis of variance) and an OCCP (orthogonal central composition plan). Over 90% gold, silver, and copper extraction was achieved with hydrochloric acid leaching in sodium hypochlorite with sodium chlorite as an oxidizing agent at 60 °C. The significance of the variation in the response for each factor, calculated using the Yates algorithm, demonstrates that by excluding sodium chloride and optimizing the doses of hydrochloric acid and sodium hypochlorite, gold can be selectively recovered through the leaching process. The scenario of HCl (2.5M)/NaClO (5%) leaching results in the maximum extraction effect of Au (91.6%) at the lowest concentrations of Ag and Cu (37–44%). [ABSTRACT FROM AUTHOR]

Recovery of nickel and cobalt from laterite ores is important to meet the demand for these metals. In this work, a process was developed for the separation of metal ions from synthetic sulfate leach liquor of laterite ores containing Fe(III), Al(III), Ni(II), Co(II), Ca(II), Mg(II), and Mn(II). First, Fe(III) and Al(III) were removed by precipitation of their hydroxides by adjusting solution pH and then Mn(II) was removed from the filtrate by oxidative precipitation with NaClO. Sequentially, Co(II) and Ni(II) from the filtrate containing Mg(II) and Ca(II) were separated by selective precipitation of CoS and NiS by adding Na2S solution, leaving Ca(II) and Mg(II) in the filtrate. The mixed precipitates of CoS and NiS were completely dissolved by 0.1 M HCl solution containing NaClO. Co(II) can be separated from Ni(II) present in the HCl solution by either oxidative precipitation with NaClO or selective extraction with saponified Cyanex 272. Optimum conditions for these procedures were obtained. Continuous experiments indicated that the purity of Co(II) and Ni(II) solutions was higher than 99%. [ABSTRACT FROM AUTHOR]

Among the technologies used for spent lithium-ion battery recycling, the common approaches include mechanical treatment, pyrometallurgical processing and hydrometallurgical processing. These technologies do not stand alone in a complete recycling process but are combined. The constant changes in battery materials and battery design make it a challenge for the existing recycling processes, and the need to design efficient and robust recycling processes for current and future battery materials has become a critical issue today. Therefore, this paper simplifies the current treatment technologies into three recycling routes, namely, the hot pyrometallurgical route, warm mechanical route and cold mechanical route. By using the same feedstock, the three routes are compared based on the recovery rate of the six elements (Al, Cu, C, Li, Co and Ni). The three different recycling routes represent specific application scenarios, each with their own advantages and disadvantages. In the hot pyrometallurgical route, the recovery of Co is over 98%, and the recovery of Ni is over 99%. In the warm mechanical route, the recovery of Li can reach 63%, and the recovery of graphite is 75%. In the cold mechanical route, the recovery of Cu can reach 75%, and the recovery of Al is 87%. As the chemical compositions of battery materials and various doping elements continue to change today, these three recycling routes could be combined in some way to improve the overall recycling efficiency of batteries. [ABSTRACT FROM AUTHOR]

Along with the transition to cleaner energy production methods, closing the processing loop on batteries is becoming one of the significant issues to tackle in this decade. The most promising recycling technique consists in the leaching of crushed cathode material, i.e. the dissolution of the solid battery material in an acid solution, to recover valuable metals from spent batteries. To lower process time and to use green organic solvents, ultrasonically enhanced leaching is a valid alternative to conventional processing. The mechanism of action of ultrasound during leaching is still unclear, and yet to be directly observed on solid particles. Therefore, this work aims to shed light on the underlying phenomena in the ultrasonically enhanced leaching process, by directly observing leached material. In particular, the focus is placed on the combined effect of ultrasound and acetic acid on NMC particles. Residual material from conventional and ultrasonically enhanced leaching was analyzed with inductively coupled plasma - optical emission spectrometry (ICP-OES), dynamic light scattering (DLS) and scanning electron microscopy (SEM). Conventional and ultrasonically enhanced leaching techniques were thus compared in terms of leaching efficiency, particle size distribution and morphological changes, demonstrating the beneficial effect of ultrasonic cavitation on mass transfer. Additionally, the NMC particles were exposed to ultrasound in water, to confirm that standalone ultrasonic cavitation does not lead to particles breakage. The understanding of the effect of ultrasound enables their targeted application in leaching processes and allows a deeper understanding of ultrasound in heterogeneous systems.

Heap leaching with a cyanide solution is used for processing low-grade ores; however, owing to the chemical, mineralogical, and physical characteristics of ores and their particle size distribution, extraction efficiencies are often low. This study investigated the effects of sodium acetate addition on gold extraction from Akshoky deposit ores under laboratory and semi-pilot laboratory test conditions. The gold-bearing ore used in this study had average gold and silver contents of 1.32 and 3.27 g/t, respectively. The chemical composition of the ore was as follows (wt%): copper: 0.0185, nickel: 0.0090, cobalt: 0.0025, zinc: 0.0470, lead: 0.0095, total iron: 4.10, calcium oxide: 3.08, magnesium oxide: 1.10, sodium oxide: 1.40, potassium oxide: 0.82, silicon oxide: 64.22, aluminum oxide: 13.37, arsenic: 0.023, antimony: 0.0024, total sulfur: 0.24, sulfate sulfur: 0.040, and sulfide sulfur: 0.20. Gold in the ore occurs in different forms: free/native form grains (82 %), covered with films (3.28 %), associated with sulfides (6.56 %), and in fine-grained form (8.20 %). Laboratory tests showed that gold dissolution from ground ore by a cyanide solution without sodium acetate addition was 83.08 %. However, with sodium acetate addition (0.1; 0.5; 1.0 kg/t), it increased to 84.38–86.61 %. Semi-pilot laboratory tests under heap-leaching conditions confirmed the positive effects of sodium acetate. The increase in gold extraction was 7.6 % (62.9 %) compared with that in the experiments without reagent addition (55.30 %).

Presented universal recommendations for the reduction of crud formation, reviewing various aspects affecting the loss of diluent and extractant due to the formation of a third phase (crud), encountered in many hydrometallurgical plants using copper solvent extraction. In this paper introduce the reasons of the crud formation , description of the stable emulsions containing solid particles and choice of technological scheme. An analysis of operations to be considered in the operation of copper solvent extraction plants is presented, due to the deterioration of copper grade below 0.5% in ore and the increase in aluminum content up to 20–25%. Results of use of extraction properties of modified extractants of ACCORGA series and unmodified extractant Lix984N on pregnant leached solution of the most important deposits (Almaly and Aktogay) are given. It is established that for solutions of Almaly deposit, ACCORGA5640 and unmodified Lix984 extractants have high selectivity to copper. Distribution of iron, silica, and copper ions during extraction was studied, and it was found that high selectivity to copper/iron and copper/silica is possessed by extractant Lix 984N, ACCORGA5640. It was found that for solutions of the Aktogay deposit, the ratio of interphase suspension in both extractants is the same, and phase separation in experiments with the use of extractant Lix 984N was 10 s shorter with the use of extractant ACCORGA5640. It was found that the addition of ACCORGACR60 reagent in the amount of 5-10 ppm also leads to a decrease in the volume of crud by 13%, for a stronger suppression of crud. [ABSTRACT FROM AUTHOR]

In general, separating osmium and ruthenium metals via hydrometallurgical methods poses significant challenges. This study presents a novel approach to separate osmium from a metallic mixture with ruthenium through selective dissolution using a two phase system. The system comprises an aqueous phase containing sulfuric acid solution with sodium chlorate and an organic phase consisting of pure tributyl phosphate. Among the several variables investigated in this work, sulfuric acid concentration and stirring speed showed most significant effect on the dissolution of osmium metal. Based on the potential-pH diagram of osmium metal, an oxidation reaction of osmium metal by the sulfuric acid and sodium chlorate mixture was proposed. The role of tributyl phosphate was to prevent the evaporation of the dissolved osmium tetroxide species by extracting into organic phase. The separation of the two metals was accomplished by selective dissolution of osmium at the following conditions: 3 M sulfuric acid, 0.7 M sodium chlorate, pure tributyl phosphate, pulp density of 2 g/L, 20°C, 60 minutes and stirring speed of 200 rpm. Use of a mixture of thiourea and hydrochloric acid solution containing ascorbic acid completely stripped the osmium from the loaded tributyl phosphate. Comparison of dissolution efficiency of osmium metal between two phase system and one phase system of sulfuric acid-sodium chlorate-water indicated that the employment of tributyl phosphate in two phase system was of importance in the recovery of the dissolved osmium species. Our results demonstrated that osmium can be separated from ruthenium by selective dissolution with the two phase system. [ABSTRACT FROM AUTHOR]

Aiming at the complexity of existing hydrometallurgical process mechanism and the poor accuracy of existing leaching process fault diagnosis methods, an improved dynamic causal diagram was studied to diagnose hydrometallurgical leaching process faults. The dynamic causal diagram was optimized and improved mainly by binary interval number, and the upper and lower limit of conditional probability were weighted to realize the fault diagnosis of hydrometallurgical leaching process. The results show that the fault diagnosis method is more accurate than the conventional method, and can diagnose the faults of leaching process more accurately. [ABSTRACT FROM AUTHOR]