Hydrometallurgical Route Research Articles

Recyclability study for the next generation of cobalt-free lithium-ion battery systems with C-LNMO, Si/C- LRLO and TiNbO-LNMO active materials via hydrometallurgical route

The scarcity and uncertain supply of cobalt poses significant challenges for the lithium-ion battery industry. To address this issue, alternative chemistries excluding cobalt have been developed. Despite solving supply issues, these developments raise concerns about recyclability and their impact on current recycling trends.This study presents a recycling strategy and evaluates its performance for next-generation cobalt-free lithium-ion batteries. It focuses on three prototypes that use innovative cathode materials (titanium niobium oxide, carbon, and silicon/carbon) and electrolyte systems (ionic liquid and gelified). The proposed recycling process includes pyrolysis, mechanical separation, neutral and acid leaching, cementation, and neutralisation for selective metal separation.The results indicate that gelified electrolytes exhibit greater thermal stability than their liquid counterparts, indicating an effect on the degradation temperature and gas emissions, which are crucial for metal recovery. This study highlights the reduced toxicity of ionic liquid electrolytes and emphasises the need for strict pyrolysis gas handling due to hazardous emissions. High recovery rates (65–90 %) were achieved for nickel, manganese, lithium, and anode components.With potential for process optimisation to improve the quality of products, this study shows that cobalt-free battery systems can be integrated into existing recycling frameworks with adjustments, supporting progress towards sustainable battery practices.

Recycling Process of Spent Alkaline and Zn-C Batteries for the Re-Utilization in Rechargeable Zn-Ion Battery

The Zn, Mn and C extraction processes from spent primary batteries and the synthesis of recycled Zn film, MnO2 and MnO2/C for Zn-ion battery application were developed in the project. The Zn, Mn and C extraction process involved the acid leaching of Zn and Mn ions from the spent alkaline and Zn-C battery electrodes in the lab-scale was initially investigated using various leaching conditions. The acid leaching using 0.5-2 M HCl and H2SO4 at ambient temperature providing Zn extraction efficiencies in a range of 72.3-95.3%. By introducing an inexpensive reducing agent namely sodium sulfide (Na2S), sodium metabisulfite (Na2S2O5) or hydrogen peroxide (H2O2) in 2M H2SO4, the Mn extraction efficiency for Mn was increased from 21.9% (with no reducing agent) up to 48.4%, 82.8% and 98.9%, respectively. The upscale leaching study was subsequently performed in a 100-L pilot scale reactor demonstrated the Zn and Mn extraction efficiencies of 71% and 65%, respectively. Using the leaching solutions from the upscale hydrometallurgical route, Zn-film fabrication via electrodeposition process, and the MnO2 and MnO2/C synthesis via hydrothermal techniques were performed. Additionally, the one-step synthesis of MnO2/C via one-step hydrothermal method with no acid leaching was also explored in this study. The recycled Zn, MnO2, MnO2/C and C residual were subsequently used as the anode and cathode main components in the CR2032 and pouch-cell rechargeable Zn-ion batteries. The recycled MnO2 and MnO2/C provided similar performance as the commercial products, which indicating the recycled MnO2, MnO2/C could be effectively utilized in the Zn-ion battery, while the utilization of recycled Zn-film provided slightly lower performance compared to that of the commercial Zn foil.

A brief review on computer simulations of chalcopyrite surfaces: structure and reactivity.

Chalcopyrite, the world's primary copper ore mineral, is abundant in Latin America. Copper extraction offers significant economic and social benefits due to its strategic importance across various industries. However, the hydrometallurgical route, considered more environmentally friendly for processing low-grade chalcopyrite ores, remains challenging, as does its concentration by froth flotation. This limited understanding stems from the poorly understood structure and reactivity of chalcopyrite surfaces. This study reviews recent contributions using density functional theory (DFT) calculations with periodic boundary conditions and slab models to elucidate chalcopyrite surface properties. Our analysis reveals that reconstructed surfaces preferentially expose S atoms at the topmost layer. Furthermore, some studies report the formation of disulfide groups (S22-) on pristine sulfur-terminated surfaces, accompanied by the reduction of Fe3+ to Fe2+, likely due to surface oxidation. Additionally, Fe sites are consistently identified as favourable adsorption locations for both oxygen (O2) and water (H2O) molecules. Finally, the potential of computer modelling for investigating collector-chalcopyrite surface interactions in the context of selective froth flotation is discussed, highlighting the need for further research in this area.

Dissolution Kinetics of Copper from Low-Grade Goldfieldite ore by Hydrometallurgical Routes

Dissolution Kinetics of Copper from Low-Grade Goldfieldite ore by Hydrometallurgical Routes

Perspectives for Photochemical Leaching Processes of Chalcopyrite: A Solar Radical-Leaching Process

This paper review presents a comparison between conventional leaching and advanced photochemical leaching processes and their potential for use in chalcopyrite leaching. Likewise, it presents an analysis of the differences between the advanced leaching processes, photoleaching and radical-leaching, indicating that the photochemical mechanisms (photooxidation/photoreduction and generation of radical oxygen species (ROS) and radical sulfur species (RSS)) would improve the oxidative dissolution of chalcopyrite, taking advantage of the high oxidizing power of free radicals. Initial experimental results of solar-assisted radical-leaching on chalcopyrite are presented, demonstrating that sulfate radicals (SO4−) allow copper to be leached at a rate 4.7 times higher than in the absence of radicals and sunlight. With these results, a radical-leaching process is presented for the first time, with a perspective toward the future development of a new hydrometallurgical route: solar-assisted radical-leaching.

Life cycle assessment of methods for recycling retired ternary lithium batteries

Electric car sales in China are soaring. However, the battery life service is generally short, leaving room for dramatic waste related to different types of ternary lithium batteries. Since batteries contain substantial amounts of toxic substances, wrong recycling methods may significantly rise environmental pollution. Currently, China's Li-ion batteries recycling technologies are poor and research dealing with the environmental impact of recycling waste ternary lithium batteries by traditional hydrometallurgical technologies in China is not sufficient. In this paper, a life cycle assessment framework was carried out to analyze the environmental impacts of recycling LiNixCoyAl1-x-yO2 (NCA) and LiNixMnyCo1-x-yO2 (NMC) batteries using conventional hydrometallurgical techniques implemented in traditional Chinese plants. The freshwater ecotoxicity, human carcinogenicity and marine ecotoxicity of NCA batteries were higher than those of NMC batteries when the batteries were recovered by the traditional hydrometallurgical recovery method. The traditional recycling method would bring more toxicity to the environment and the traditional hydrometallurgical route is not suitable for recycling NCA-type ternary lithium batteries. Moreover, the recycling process of all three types of batteries displayed an impact on the environment with negative growth and the highest impact on the environment during the initial stage of recycling. Overall, new directions and technical updates for China's power battery recycling enterprises were provided, which can be useful for future planning.

Extraction of alumina from fly ash by pyro-hydro metallurgical routes: A review

Fly ash is a resulting by-product formed due to the burning of pulverized coal on a steam-generating plant. Fly ash mainly contains alumina and silica, hence it can be an excellent secondary source for alumina. Today only 30% of global fly ash can be reused commercially, the remaining was dumped. This causes waste of resources and environmental pollution too. The alumina in the fly ash was in the form mullite phase which is a stable phase so decomposition of this phase is difficult. The mullite phase can be disilicated by calcination, roasting, etc which were pyro-metallurgical routes. Alumina can be extracted as aluminum hydroxide and other unstable forms from fly ash by hydrometallurgical routes. This process requires a huge amount of energy for reaction which is a major drawback of this process. Till now industrial extraction of alumina from fly ash cannot be feasible. Different researchers and scholars did various works to overcome this difficulty. This paper presents a review for extraction of alumina via these routes. It starts with different concepts used in extraction of alumina from fly ash. The middle portion presents the survey of work done by different scholars. The work finally concludes with future possibilties.

BHOEOCC6/n-dodecane: A new solvent extraction media for Cs removal from nuclear waste without using any phase modifier

Modifier-free diluent is most advantageous in hydrometallurgical route for separation of any radioactive element from high level liquid waste (HLLW). However there is not even a single calix crown reported in the literature that is soluble in pure n-dodecane and shows very high Cs extraction from such high nitric acid condition of 4.0 M prevalent in HLLW. Herein we designed a new calix crown-6-ether with an aim to reduce polarity so as to increase solubility in n-dodecane for extraction of Cs by density functional theory (DFT). The theoretically designed calix crown has been synthesised by introducing two 2-(hexyloxy)ethoxy alkyl arms at 1, 3 position calix[4]-arene framework and abbreviated as BHOEOCC6. Characterisation of BHOEOCC6 was carried out using 1H NMR, 13C NMR, and ESI-MS etc. techniques. 0.1 M BHOEOCC6/n-dodecane mixture shows exceptionally high stability as well as high Cs extraction ability (DCs = 10.75 @ 4.0 M HNO3) from highly acidic nuclear waste solution. The mechanism and interaction of Cs with BHOEOCC6 were also probed by experimental distribution ratio studies and instrumental techniques of UV–VIS titration and NMR studies of Cs-BHOEOCC6 complex.

Overview of Recycling Techniques for Lithium-Ion Batteries

This paper presents a literature review on the processing of used lithium-ion batteries in both industry and research. On an industrial scale, lithium-ion batteries are primarily processed through pyrometallurgical methods, leading to incomplete utilisation of lithium cells. On the other hand, the hydrometallurgical route of recycling lithium-ion batteries poses challenges, such as large-scale discharging or inert gas pretreatment, largely due to explosion hazards. Modern methods of lithium-ion battery recycling are oriented toward refining the leach liquor through solvent extraction methods using D2EHPA and Cyanex 272, to recover Co, Mn, and Ni. The final Li product is obtained through Na<sub>2</sub>CO<sub>3</sub> precipitation.

Reduction of natrojarosite and laterite nickel ore leaching residue composite using palm kernel shell reducing agents at temperatures of 1300-1450℃

Lateritic nickel ore processing through hydrometallurgical route generates a significant amount of residue from the leaching stage. Two examples of hydrometallurgical process residues, namely natrojarosite and leaching residue can potentially be used as secondary raw materials for the iron and steel industry. A relatively high sulfur content of up to 12% is a severe issue because the sulfur threshold value for steel raw materials is 1%. Therefore, it is necessary to reduce the sulfur content in natrojarosite and leaching residue to meet the standards as a secondary raw material for the iron and steel industry. In this research, reduction of natrojarosite, laterite nickel ore leaching residue, and palm kernel shell reducing agents composite was conducted in varying amounts of palm kernel shell reductant of 25-100% using a non-isothermal method at an initial temperature of 1000°C with a final temperature of 1300-1450°C and an isothermal method of 1000°C, 1300°C, and 1450°C for 2 hours. The results showed that an excessive amount of reductant (≥25%) would inhibit the formation of iron metal at macrosize (above 0.35 mm). Reduction, both by non-isothermal and isothermal methods, results in decreasing sulfur content in the metal phase as the reduction temperature increases, but a sulfur-rich matte phase is still observed in all experimental conditions. The proportion of the metal phase produced is getting higher and more separated from the slag phase as the temperature increases. The optimum condition was obtained at a non-isothermal reduction of 1450°C using a 25% reducing agent which resulted in iron and sulfur content in the metal phase of 88.53% and 0.49%, respectively, with a metal-matte phase proportion of 65.56%. In this case, slag was dominated by liquid phase with a FeO content of 7.64% and a viscosity of 7.313 PaS.

Preparation of industrial ammonium diuranate from a boltwoodite ore as a mediator for nuclear fuel and catalytic utilizations

To date, uranium is one of the most crucial critical metals and a high supply-demand gap is forecasted in the coming years. However, the upsurging interest in uranium in nuclear fuel cycles prompted an engineered hydrometallurgical route capable of producing a high-grade ammonium diuranate [(NH4)2U2O7] capable of serving as an intermediate in nuclear base fuel and catalytic industries. Consequently, the processing of an indigenous boltwoodite ore containing admixtures of albite (Na2.00Al2.00Si6.00O16.00), boltwoodite (Na2.00K2.77U3.00Si6.00O9.00H4.00), thorite (Th4.00Si4.00O16.00), and quartz (Si6.00O6.00) by the hydrometallurgical process was examined in hydrochloric acid media. The experimental parameters during leaching including lixiviant concentration, reaction temperature, and particle size on the ore dissolution were investigated. At established conditions (2.5 mol/L HCl, 75 °C, 75 μm), 99.1% of the initial 10 g/L ore was dissolved within 120 min. The estimated activation energy of 17.30 kJ/mol indicated a mixed control reaction mechanism as the rate-determining step for the ore dissolution. The thermodynamic and kinetic tests were also examined to explore dissolution feasibility. The apparent change in enthalpy (ΔH = 73.95 kJ/mol) and negative values of Gibb's free energy change affirmed that the U(VI) extraction is endothermic and spontaneous for temperatures between 300 K and 348 K. Almost 99.3% U(VI) in the pregnant solution was quantitatively extracted using TBP in kerosene, and 97% of the total U(VI) was quantitatively precipitated using NH4OH solution. The precipitate was further crystallized to obtain industrial-grade ammonium diuranate comparable with the international standard specification of nuclear purity ASTM C 788–03; recommended to serve as a mediator in the nuclear fuel and catalytic industries.

A near-zero waste process for the full-component utilization of deep-sea polymetallic nodules based on reductive leaching with SO2 followed by separation and recovery

Recovery of critical metals from marine minerals is a promising option to ensure the sustainable supply of critical metals, but existing recovery processes suffer from technical bottlenecks in terms of low resource utilization and large waste discharge. This paper presents a complete hydrometallurgical route for the full-component utilization of deep-sea polymetallic nodules (DPN). Leaching experiments were first carried out in the presence of SO2 because cheap SO2 can destroy the original mineral structure based on a reductive mechanism. The leaching efficiencies of Ni, Co, Mn, Cu, La, Ce, and Fe were reached 99.2%, 99.3%, 98.7%, 95.9%, 95.3%, 95.4%, and 91.4%, respectively, under the optimal conditions of 30 °C, L/S ratio of 6:1 mL/g, H2SO4 dosage of 37.5 wt%. The downstream process aimed at the sequential recycling of metal ions from the pregnant leach solution (PLS) consists of Fe recovery by the hematite process, selective solvent extraction of Cu and rare earth elements (REEs), co-extraction of Ni/Co/Mn, and Mn electrowinning. As a result, high-grade hematite (60 wt% of Fe), industrial-grade CuSO4, mixed rare earth oxides, battery-grade (Ni, Co, Mn)SO4 solution, and electrolytic manganese were obtained. During the whole process, the recovery efficiency of Ni, Co, Mn, Cu, La, Ce, and Fe reached 97.1%, 97.1%, 96.9%, 91.5%, 91.1%, 91.1%, and 91.3%, respectively. Since the hydrometallurgical process achieves the resource utilization of all the DPN constituents, it has the advantages of near-zero waste and low energy consumption.

Early-stage application of process mineralogy methodologies for mineral tracking in flotation of rare earth elements (REE)-bearing minerals from a deposit in Norway

The Fen carbonatite complex, situated in Vestfold and Telemark County, South Norway, is one of the largest known rare earth elements (REE) deposits in Europe with ongoing exploration drilling. Literature regarding the complex processing of the Fen ore is lacking, and thus, the present work investigates for the first time its beneficiation potential and applies process mineralogy studies to understand in a sound manner the performance variations during the processing of REE ore. Flotation kinetics studies revealed that (i) high concentration of total REE-oxide (TREO) can be achieved during rougher flotation; (ii) the high concentration of sulphur (in form of pyrite as main sulphide) can be achieved at the beginning of flotation; (iii) the highest concentration of TREO can be reached after flotation of S. Further processing (i.e., by the addition of cleaning stages and grinding) has a potential to improve the overall recovery of TREO and S. However, the decision of further processing will depend, among other factors, on the definition of following hydrometallurgical routes (e.g., leaching, solvent extraction) and the economic aspects of the overall process. So far, the reported results show that a rather flexible process can be achieved for the material from the Fen deposit.

A hydrometallurgical perspective of aluminium dross recycling

To meet the objective of recovering aluminium from aluminium dross, it is essential to recycle it and save natural resources for posterity. Aluminium dross, a waste generated in an enormous quantity, is formed over the top surface of the molten bath when the surrounding oxygen comes into contact and forms a thick semi-solid layer of oxide. Pure metallic aluminium, which is entrapped within the oxides, is extracted using three different routes i.e., Pyrometallurgy, hydrometallurgy and hydrothermal. Metallic aluminium is recovered using the pyrometallurgical route by melting dross in a rotating furnace. In hydrometallurgy, chemical treatments of dross ensures the synthesis of a wide range of products. Newly developed technique like hydrothermal is used to produce zeolites, molecular sieves, and many other useful products. Apart from the solid products, gases like H2, NH3 and CH4 are produced by recycling dross when the Al-water reaction takes place in the presence of acids or alkalis. The present study comprises major aspects of dross recycling via the hydrometallurgical route.

Sequential recovery of copper, nickel, gold, silver and zinc from WPCBs of obsolete mobile phones through hydrometallurgical recycling

Waste printed circuit board (WPCB) of an obsolete mobile phone is a valuable source of base and precious metals. Alternatively, WPCBs also contain various lethal and toxic constituents which introduce ecological impacts while landfilling and incineration. Recycling WPCB is essential to reduce the environmental effects and to recover valuable metals. This article employs a hydrometallurgical route for the sequential recovery of copper, nickel, gold, silver and zinc from WPCBs through leaching, solvent extraction and cementation processes. Initially, the metal clads of WPCBs are used for the leaching of copper, nickel and other base metals without any selective dissolution of gold and silver. Optimal results revealed that dilute nitric acid at room temperature provides effective leaching (99.9%) of copper, nickel and zinc by leaving precious metals gold and silver in the residue. The utilization of phenolic oxime as a solvent extraction reagent revealed the selective recovery of copper and nickel from the leach liquor individually. The availed residue is dissolved in the halide salts in the presence of acidic conditions showing the quantitative dissolution of gold and silver. Solvent extraction with amide-based reagents recovered gold by leaving the silver-rich raffinate. A cementation technique with copper powder is implemented for the precipitation of silver. The proposed approach delivers an effective, eco-friendly and economically feasible process for the sequential recovery of metallic values from WPCBs of obsolete mobile phones.

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard-metal waste enhancement

Peculiar chemical, mechanical, and magnetic properties make cobalt a key metal for a variety of “hot” applications like the cathode production of Li-ion batteries. Cobalt is also the preferred metallic binder for tungsten carbide tool manufacturing. The recent increasing criticality of cobalt and tungsten is driving the interest of manufacturers and researchers toward high-rate recycling of hard-metal (HM) waste for limiting the demand for raw materials. A simple and environmentally friendly hydrometallurgical route for Co-selective dissolution from HM wastes was developed by using weak, bio-derived, and biodegradable organic acids (OAs). In this study, OAs, namely, acetic (HAc), citric (H3Cit), maleic (H2Mal), lactic (HLac), succinic (H2Suc), lactobionic (HLB), and itaconic (H2It) acids, were selected for their pKa1 values spanning from 1.8 to 4.7 and systematically tested as selective cobalt leaching agents from WC-Co-based wastes in water, isolating the formed complexes in the solid state. Thereby, all of them seemed to be efficient in selective Co leaching, achieving almost quantitative Co dissolution from HM by-products still at low concentration levels and room conditions in a short time, leaving the residual WC unreacted and ready to be re-employed for industrial purposes. Nevertheless, two main categories of organic acids were distinguished depending on their oxidizing/complexing behavior: class 1 OAs, where the metal oxidation is carried out by H+, and class 2 OAs, where oxidation is carried out by an external oxidant like O2. A combined experimental/theoretical investigation is described here to show the reasons behind this peculiar behavior and lay the foundation for a wider discussion on the leaching capabilities of OAs toward elemental metals. Due to the demonstrated effectiveness, low cost, eco-friendliness, and large availability through biotechnological fermentative processes, particular attention is devoted here to the use of HLac in hydrometallurgy as an example of class 2 OA. WC-Co materials recovered by HLac mild hydrometallurgy demonstrated a metallurgical quality suitable for re-employment in the HM manufacturing process.

Recovery of Rare Earth Elements from the Leaching Solutions of Spent NdFeB Permanent Magnets by Selective Precipitation of Rare Earth Oxalates

After mechanical pre-treatment, the typical hydrometallurgical route of NdFeB magnet recycling starts with leaching in acidic solutions. However, due to the high concentration of iron ions in the leaching solution, the selective recovery of rare earths from the solution is challenging. In our work, the selective precipitation of rare earth oxalates as a potential separation method was proposed. The precipitation of neodymium oxalate was first tested on model solutions, which was then followed by experimental tests carried out on real solutions after the leaching of NdFeB magnets. The recovery of rare earths in the form of oxalates was investigated with the use of different amounts of oxalic acid in relation to its stoichiometric amount. The most efficient separation of rare earths was observed in the case where sulfuric acid was used for leaching. The use of oxalic acid in stoichiometric amounts resulted in the precipitation of about 93% of all rare earths present in the solution, whereas the concentration of Fe and other elements (Ni, Co, and B) practically did not change. An increase in oxalic acid of 20% and 40% more than the stoichiometric amount (100%) led to the increase in the precipitation efficiency of rare earths to 96.7% and 98.1%, respectively. However, the use of oxalic acid in a 1.4 ratio caused a 7% decrease in Fe concentration, which suggests Fe co-precipitation. In order to investigate a possibility of further increasing the separation of rare earths from iron, an additional method was tested, in which iron was first oxidized from Fe2+ to Fe3+ before the precipitation of rare earth oxalates.

Simplified hydrometallurgical route for the synthesis of silica-free hematite from iron ore tailings

The processing of iron ore generates large volumes of tailings. Acid leaching enables the solubilization of iron in an aqueous solution, allowing the production of ferric liquor and a silica-rich residue. The purpose of this investigation was to use the leachate resulting from this process to synthesise high-quality iron oxide. The conducted methodology involved acid leaching, selective iron precipitation as a function of pH, and the thermal conversion of the precipitated iron oxy-hydroxides into iron oxide particles. The iron oxide consisted of micro/nano Fe2O3 particles which were free of silica, with iron contents of 64% and particle sizes of less than 28 μm. The process presented an overall iron recovery around 84%. The resulting material could be used as a commercial pigment or be incorporated into steel-making iron pellets. The hydrometallurgical conversion of iron ore wastes into valuable products may contribute to the future of mining and to green steel production.

Combined hydrometallurgical route for recovery of metals from spent LIB using hydrochloric acid and phosphonium ionic liquid

ABSTRACT This research explored the significance of Cyphos IL 101 in recovering metal values from waste LiMn2O4 batteries. Several leaching parameters were investigated to recover metals from the leach liquor of the battery material. The maximum leaching efficiency of Li (100%) and Mn (99.6%) was attained with 3.0 mol/L hydrochloric acid, 30°C, S/L ratio of 10 g/L, and 60 min leaching duration. The leaching process was diffusion-controlled. At pH 5.5, the separation of manganese and lithium exhibited excellent selectivity towards manganese over lithium using 0.1 mol/L Cyphos IL 101. 99.6% manganese extraction and negligible lithium extraction were obtained with two stages of counter-current extraction at A/O 1:1 predicted by the McCabe-Thiele plot. Using 0.1 mol/L hydrochloric acid, a stripping efficiency of 99.4% was attained for manganese.

Platinum Group Metals: Green Recovery from Spent Auto-Catalysts and Reuse in New Catalysts—A Review

This manuscript reviews the current trends in the recovery of Platinum Group Metals (PGMs) from end-of-life autocatalysts and the aims of the recently funded Marie Sklodowska-Curie Project “Chemistry of Platinum Group Metals-CHemPGM” towards the greening of PGMs recovery processes and the reusing of recovered PGMs for preparation of new catalysts. Together with the analysis of the state of the art recovery of PGMs from spent autocatalysts through pyrometallurgical and hydrometallurgical routes and the recent trends in reducing their environmental impact, also emerging sustainable and green technologies are analyzed. Particular focus is given on the mechanochemical processing as a promising sustainable route not only for the pretreatment of waste materials but also for direct PGMs leaching. The present review identifies also the trends in catalysts for carbon neutrality and the few recent efforts in developing PGM-based catalysts starting directly from the liquor of the leach solutions of spent catalysts envisaging therefore a possible key to close PGMs loop in a more efficient and sustainable way.