Search Results (192)

Magnesium is a valuable industrial metal prized for its strength and reactivity. Traditionally, magnesium was extracted from seawater and brines. However, to meet the rising global demand, it is now primarily sourced from mineral deposits. This shift has sparked renewed interest in extracting magnesium from non-saline sources, including carbonates, silicates, halides, oxides, and hydroxides. This review examines the extraction technologies currently used for these mineral-based resources, including pyrometallurgical, hydrometallurgical, and electrometallurgical methods. Each method is assessed based on the reactions involved in the transformation, operational principles, efficiency, and energy requirements. The review emphasizes the importance of mineral pretreatment—thermal, mechanical, and chemical—in improving magnesium recovery, especially from refractory silicates. By summarizing recent advancements and process innovations, the review aims to inform future research and industrial practices, and support the development of sustainable, cost-effective, and scalable magnesium extraction strategies. Full article

For the first time, an alternative and sustainable approach is reported using phenyl-2-pyridyl ketoxime (PPKO) as a selective extracting agent for the recovery of Cu(II) from alkaline solutions in the presence of tartrate ions. The advantages relative to conventional processes carried out in acidic media are outlined. Through potentiometric and spectrophotometric analyses, the sequential formation of a 1:2 metal cation–ligand Cu(II)-(PPKO)₂ complex was identified as the predominant species in alkaline aqueous solutions. The high removal capacity of the extractant for Cu(II), as assessed from liquid–liquid extraction, and its efficient performance are comparable to widely used commercial extractants. Thermodynamic studies of the complexation between the copper(II) ion and PPKO demonstrated that the process exhibits an endothermic character. A progressive decrease in the performance of the extractant was observed after reuse without a regenerative treatment. This deterioration was partially reversed through a controlled reprotonation process using an acetate buffer solution. Overall, the results support the potential of PPKO as an effective and selective alternative ligand for hydrometallurgical applications in alkaline medium. Full article

The traditional recycling process of spent lithium-ion battery(LIB) with high Mn content faces the defects of high cost of neutralization and precipitation, poor economics of Mn extraction, and serious Li loss. Therefore, this paper introduces a comprehensive hydrometallurgical method for extracting valuable metals from high-Mn spent LIB. Particularly, directional precipitation of Mn was achieved by utilizing its redox properties, and shot-process extraction and enrichment of Li was realized by using the extractant HBL121. In a sulfuric acid system, control of the oxidant dosage to 0.8% resulted in high leaching efficiencies for Li, Ni, Co, and Mn, with values of 96.58%, 96.13%, 95.22%, and 94.24%, respectively, under optimal conditions which were C(H₂SO₄) of 3.5 mol/L, V(H₂O₂) of 0.8% (v/v), L/S of 10:1, temperature of 60 °C, and time of 60 min. Subsequently, the addition of KMnO₄ dosage (K_p/K_t) in a ratio of 1:1 resulted in the precipitation of 98.47% of Mn as MnO₂, with Ni and Li precipitation efficiencies of 0.2% and 0.1%, respectively. Cascade extraction of Ni and Co was reached by using Cyanex272 extractant from the solution after Mn precipitation. At an organic-to-aqueous phase ratio (O/A) of 1:5, the Co extraction efficiency reached 98.68%, whereas the loss efficiency of Ni was 5.53%, and Li was less than 0.1%. Adjusting the O/A to 1:1 increased the Ni extraction efficiency to 89.99% and Li loss to 8.95%. Finally, the HBL121 extractant was utilized to extract Li from the Li-rich solution, achieving 95.08% extraction efficiency. The Li was stripped with 2 mol/L H₂SO₄ from the load organic phase, realizing a Li concentration of 11.44 g/L. Thus, this process facilitates the comprehensive and efficient recovery of valuable metals such as Li, Ni, Co, and Mn from spent high-Mn LIB. Full article

This study aims to develop an environmentally friendly hydrometallurgical process for the recovery of zinc from zinc oxide ores. The process includes monosodium glutamate (MSG) leaching, followed by zinc recovery from the pregnant leach solution via electrowinning, and the recirculation of the spent solution to the leaching stage. The study investigated the effects of key leaching parameters and identified the optimal conditions as a pH of 9.5, temperature of 70 °C, 5 h leaching time, solid-to-liquid ratio of 50 g/L, particle size of d₈₀ = 115 µm, and initial MSG concentration of 1.0 M. Under these conditions, 82.3 ± 0.05% of the zinc was extracted with minimal co-dissolution of impurities. Subsequent electrowinning at 100 A/m² for 150 min yielded 74.97 ± 2.43% zinc recovery with 96.4 ± 0.76% purity. The process achieved a current efficiency of 87.08%, while the specific energy consumption was calculated to be 3.98 kWh per kilogram of zinc recovered. The reusability of MSG was examined by recirculating spent electrowinning solution back to the leaching stage. Zinc extraction decreased from 82.2% to 28.5% over three electrowinning–leaching cycles, due to MSG degradation during electrowinning. The results of this study demonstrated that MSG is a selective and effective lixiviant for zinc recovery, while underlining the limitations of its reuse. Full article

As in the case with other metals, tungsten is an element with a number of uses in different fields, which is why its recovery from both primary and secondary materials continues to be of great interest. Various hydrometallurgical processes, considered as unit operations, can be used for the recovery, separation and concentration of tungsten from any source, with ease of scaling-up a potential factor when considering the best process for practical use. The present work reviewed investigations into the use of such unit operations for the recovery of tungsten which were published during 2024 and the first half of 2025. Because most if not all of these investigations were conducted on a laboratory scale, there is still much room for improvement before deciding on the best option for tungsten recovery. In all cases, however, this recovery is based on a series of steps from leaching to separation technologies (ion exchange resins, liquid–liquid extraction, etc.) to the tungsten end-product. Full article

Sustainable copper extraction presents significant challenges due to waste generation and environmental impacts, requiring advanced predictive methodologies to optimize production processes. This study addresses a gap in applying deep learning to forecast hydrometallurgical copper production by comparing six recurrent neural network architectures: Vanilla LSTM, Stacked LSTM, Bidirectional LSTM, GRU, CNN-LSTM, and Attention LSTM. Using time-series data from a full-scale industrial operation, we implemented a data augmentation approach to overcome data scarcity limitations. The models were evaluated through rigorous metrics and multi-step forecasting tests. The results demonstrated remarkable performance from five architectures, with Bidirectional LSTM and Attention LSTM achieving the highest accuracy (RMSE < 0.004, R² > 0.999, MAPE < 1%). These models successfully captured and reproduced complex cyclical patterns in copper mass production for up to 500 time steps ahead. The findings validate our data augmentation strategy for enabling models to learn complex known cyclical patterns from limited initial data and establish a promising foundation for implementing AI-driven predictive systems that can enhance process control, reduce waste, and advance sustainability in hydrometallurgical operations. However, these performance metrics reflect the models’ ability to reproduce patterns inherent in the augmented dataset derived from a single operational cycle; validation on entirely independent operational data is crucial for assessing true generalization and is a critical next step. Full article

The increasing need-based demand for lithium iron phosphate (LFP) batteries in electric vehicles and energy storage systems necessitates the development of efficient and sustainable recycling methods. This study investigates the effect of oxidative roasting on lithium extraction from industrially sourced LiFePO₄ (LFP) blackmass containing high graphite content (~46%) and mixed electrode materials. Roasting at 650 °C for one hour converted LiFePO₄ into water-soluble Li₃Fe₂(PO₄)₃ and Fe₂O₃, while reducing carbon and fluorine levels. However, contrary to expectations, mild-acid leaching (pH 2, 40 g/L, 20 °C) of roasted blackmass did not improve lithium recovery compared to unroasted material, yielding approximately 33% extraction efficiency. Strong-acid leaching (pH 0, H₂SO₄/H₂O₂) achieved over 95% lithium recovery but also resulted in significant co-dissolution of iron and other impurities. Our XRD and SEM analyses showed that some lithium-containing phases remained in the residue after water leaching, while acid leaching left mainly iron oxide and graphite. These results suggest that, for complex and graphite-rich industrial blackmass, roasting may not always deliver the expected boost in lithium recovery. Our findings highlight the need to tailor recycling processes to the specific characteristics of battery waste and suggest that direct hydrometallurgical methods could be more effective for complex, impurity-rich LFP blackmass streams. Full article

Red mud from bauxite processing is among the large-tonnage technogenic waste that poses a significant ecological threat. At the same time, red mud serves as a raw material source for expanding the resource base for obtaining iron, rare metals, and rare earth elements. Numerous studies on their utilization have shown that only through comprehensive processing, combining pyrometallurgical and hydrometallurgical methods, is it possible to maximize the extraction of all the useful components. This work addresses the first stage of a comprehensive technology for processing red mud through reduction smelting, separating iron in the form of pig iron, and producing slag. Studies were conducted on the reductive smelting of red mud using waste slurry from alumina production as the calcium-containing material, taken in proportions calculated to obtain a fluid slag with a hydraulic modulus of 0.55–0.8. The permissible mixing range of red mud with waste slurry was determined to be in the ratio of 0.56–1.2. In cases where the charge was prepared in violation of the required hydraulic modulus value, pig iron was not obtained during smelting. When the hydraulic modulus requirement was met, the temperature of the reductive smelting process was 1350–1400 °C. The total amount of recovered iron obtained as pig iron and fine fractions amounted to 99.5% of the original content. The low iron content (0.23–0.31%) in the non-magnetic slag fraction allows for the production of high-quality titanium oxide and rare earth element concentrates in the subsequent stages of the comprehensive hydrometallurgical processing of red mud, involving acid leaching. Based on the results of a phase analysis of the slag, pig iron, and melt, the reactions of the reductive smelting process were established, and their thermodynamic likelihood was determined. In fluid slags, the content of the sodium aluminosilicate phase is twice as high as that in slag with a higher hydraulic modulus. The reductive smelting of 100% red mud with the addition of calcium oxide, calculated to achieve a hydraulic module of 0.55 at a temperature of 1350–1400 °C, produced pig iron and slag with high alkali and iron contents. Full article

Objective: The rapid growth of electric vehicle (EV) adoption has led to an unprecedented increase in lithium-ion battery (LIB) demand and end-of-life waste, underscoring the urgent need for effective recycling strategies. This review evaluates current progress in EV battery recycling and explores future prospects. Design: Review based on PRISMA 2020. Data sources: Scientific publications indexed in major databases such as Scopus, Web of Science, and ScienceDirect were searched for relevant studies published between 2020 and 15 April 2025. Inclusion criteria: Studies were included if they were published in English between 2020 and 15 April 2025, and focused on the recycling of electric vehicle batteries. Eligible studies specifically addressed (i) recycling methods, technologies, and material recovery processes for EV batteries; (ii) the impact of recycled battery systems on power generation processes and grid stability; and (iii) assessments of materials used in battery manufacturing, including efficiency and recyclability. Review articles and meta-analyses were excluded to ensure the inclusion of only original research data. Data extraction: Data were independently screened and extracted by two researchers and analyzed for recovery rates, environmental impact, and system-level energy contributions. One researcher independently screened all articles and extracted relevant data. A second researcher validated the accuracy of extracted data. The data were then organized and analyzed based on reported quantitative and qualitative indicators related to recycling methods, material recovery rates, environmental impact, and system-level energy benefits. Results: A total of 23 studies were included. Significant progress has been made in hydrometallurgical and direct recycling processes, with recovery rates of critical metals (Li, Co, Ni) improving. Second-life battery applications also show promise for grid stabilization and renewable energy storage. Furthermore, recycled batteries show potential in stabilizing power grids through second-life applications in BESS. Conclusion: EV battery recycling is a vital strategy for addressing raw material scarcity, minimizing environmental harm, and supporting energy resilience. However, challenges persist in policy harmonization, technology scaling, and economic viability. Future progress will depend on integrated efforts across sectors and regions to build a circular battery economy. Full article

The rapid growth in lithium-ion battery (LIB) demand has underscored the urgent need for sustainable recycling methods to recover critical metals such as lithium, cobalt, nickel, and manganese. Traditional pyrometallurgical and hydrometallurgical approaches often suffer from high energy consumption, environmental impact, and limited metal selectivity. As an emerging alternative, solvometallurgy, and in particular the use of low-melting mixtures solvents, including deep eutectic solvents, offers a low-temperature, tunable, and potentially more environmentally compatible pathway for black mass processing. This review presents a comprehensive assessment of the recent advances (2020–2025) in the application of LoMMSs for metal recovery from LCO and NCM cathodes, analyzing 71 reported systems across binary, ternary, hydrated, and non-ChCl-based solvent families. Extraction efficiencies, reaction kinetics, coordination mechanisms, and solvent recyclability are critically evaluated, highlighting how solvent structure influences performance and selectivity. Particular attention is given to the challenges of lithium recovery, solvent degradation, and environmental trade-offs such as energy usage, waste generation, and chemical stability. A comparative synthesis identifies the most promising systems based on their mechanistic behavior and industrial relevance. The future outlook emphasizes the need for greener formulations, enhanced lithium selectivity, and life-cycle integration to support circular economy goals in battery recycling. Full article

Antimony (Sb) is a metalloid widely used in different areas—from the cutting-edge renewable energy technologies to “classical” lead acid batteries. Its availability in primary sources is limited, and these sources are geographically unevenly distributed worldwide. Antimony use will increase in the future. That is why Sb is included in the critical raw material lists of the European Union and the USA. In order to mitigate the future Sb shortage, Sb recovery from industrial residues is worth considering. This paper presents the availability of Sb in nonferrous metals extraction waste and the applicability of the hydrometallurgical route for Sb recovery from such sources. Leaching is emphasized. The use of acidic and alkaline leaching methods, their recent modifications, and the effect of different process parameters (reagents’ type, solid-to-liquid ratio, temperature, and the addition of oxidizing reagents) are highlighted. The use of new leaching systems, such as deep eutectic solvents and non-aqueous solutions, is presented. Initial attempts to apply bioleaching are described. Finally, some proposals for future investigations are given. Full article

The increasing demand for lithium-ion batteries (LIBs) and their limited lifespan emphasize the urgent need for sustainable recycling strategies. This study investigates the application of tetrabutylphosphonium-based ionic liquids (ILs) as alternative leaching agents for recovering critical metals, Li(I), Co(II), Ni(II), and Mn(II), from spent NMC cathode materials. Initial screening experiments evaluated the leaching efficiencies of nine tetrabutylphosphonium-based ILs for Co(II), Ni(II), Mn(II), and Li(I), revealing distinct metal dissolution behaviors. Three ILs containing HSO₄⁻, EDTA²⁻, and DTPA³⁻ anions exhibited the highest leaching performance and were selected for further optimization. Key leaching parameters, including IL and acid concentrations, temperature, time, and solid-to-liquid ratio, were systematically adjusted, achieving leaching efficiencies exceeding 90%. Among the tested systems, [TBP][HSO₄] enabled near-complete metal dissolution (~100%) even at room temperature. Furthermore, an aqueous biphasic system (ABS) was investigated utilizing [TBP][HSO₄] in combination with ammonium sulfate, enabling the complete extraction of all metals into the salt-rich phase while leaving the IL phase metal-free and potentially suitable for reuse, indicating the feasibility of integrating leaching and extraction into a continuous, interconnected process. This approach represents a promising step forward in LIB recycling, highlighting the potential for sustainable and efficient integration of leaching and extraction within established hydrometallurgical frameworks. Full article

It has been demonstrated that the traditional hydrometallurgical method is still economically viable in several industrial applications such as Bayer, Boix, Platsol, Sherrit-Gordon, and so on. The conventional extraction technique of valuable metals from their ores using an aqua medium has several challenges. The following can be listed for the illustration of this: (1) Inorganic acids used during the leaching process have been proven to be non-environmentally friendly and ready to lead to non-selective processes in general, except in rare cases used in alkaline environments. (2) Special linings are required in the reactors used due to the corrosive impact of acids such as HCl and H₂SO_4, especially when leaching at high temperatures, rendering all processes costly. (3) Practically, using inorganic acids while leaching samples containing amorphous silicate phases leads to gel formation. Solvometallurgy overcomes these challenges by substituting the aqueous phase for other polar solvents, such as polar molecular organic or ionic solvents. The advantage of this substitution lies in the ability to manipulate metal ion distribution using solvents with varying solvation properties. This review examines the potential of solvometallurgical processes (solvoleaching) over conventional hydrometallurgy as viable alternatives for metal extraction from sulfide ores. It highlights the key distinctions between hydrometallurgy and solvometallurgy while emphasizing the potential economic and environmental advantages solvometallurgy offers. Full article

The use of Li-ion batteries is drastically increasing, especially due to the growing sales of electric vehicles. Simultaneously, there is a shift towards exchanging the traditional Co- and Ni-rich electrode materials with more sustainable alternatives such as LiFePO₄. This transition challenges conventional recycling practices, which typically rely on shredding batteries into a substance known as black mass, which is subsequently processed via hydrometallurgical or pyrometallurgical methods to extract valuable elements. These routes may not be economically viable for future sustainable chemistries with lower contents of high-value metal. Hence, new methods for processing the black mass, allowing, e.g., for physical separation and direct recycling, are direly needed. Such developments require that the black mass is thoroughly understood. In this study, we thoroughly characterize a commercially produced Graphite/LFP black mass sample from real battery waste using a suite of analytical techniques. Our findings reveal detailed chemical, morphological, and structural insights and show that the components in the black mass have different micro-size profiles, which may enable simple size separation. Unfortunately, our analysis also reveals that the employed processing of battery waste into black mass leads to the formation of an unknown Fe-containing compound, which may hamper direct recycling routes. Full article

This study presents an innovative approach to processing refractory zinc-bearing clinker using microwave thermal treatment followed by acid leaching. Microwave irradiation induces phase transformations, converting sphalerite (ZnS) to zincite (ZnO), and generates microcracks that enhance clinker porosity and reactivity. These changes significantly improve zinc dissolution during sulfuric acid leaching. Key parameters—acid concentration, temperature, solid-to-liquid ratio, and leaching time—were optimized, achieving a zinc extraction of 92.5% under optimal conditions (40 g/L H₂SO₄, solid-to-liquid ratio 1:4, 600 °C, 5–7 min) compared to 39.1% without pre-treatment. Thermodynamic analysis confirms the higher reactivity of ZnO, driven by favorable Gibbs free energy and exothermic reaction characteristics. These findings demonstrate the potential of microwave processing to intensify hydrometallurgical processes, offering energy efficiency and environmental benefits for industrial zinc recovery. Full article