Process For Recovery Of Metals Research Articles

Mechanism of highly efficient oil removal from spent hydrodesulfurization catalysts by ultrasound-assisted surfactant cleaning methods

The removal of crude oil from spent hydrodesulfurization catalysts constitutes the preliminary stage in the recovery process of valuable metals. However, the traditional roasting method for the removal exhibits massive limitations. In view of this, the present study used an ultrasound-assisted surfactant cleaning method to remove crude oil from spent hydrodesulfurization catalysts, which demonstrated effectiveness. Furthermore, the study investigated the mechanism governing the process with calculation and experiments, so as to provide a comprehensive understanding of the cleaning method’s efficacy. The surfactant selection was predicated on the performance in the IFT test, with SDBS and TX-100 finally being chosen. Subsequent calculations and analysis were then conducted to elucidate their frontier molecular orbitals, electrostatic potential, and polarity. It has been found that both SDBS and TX-100 possess the smallest LUMO-HOMO energy gap (ΔE), registering at 4.91 eV and 4.80 eV, respectively, and presenting the highest interfacial reactivity. The hydrophilic structure in the surfactant regulates the wettability of the oil-water interface, and the long-chain alkanes have excellent non-polar properties that promote the dissolution of crude oil. The ultrasonic-assisted process further improves the interface properties and enhances the oil removal effect. Surprisingly, the crude oil residue was reduced to 0.25% under optimal conditions. The final phase entailed the techno-economic evaluation of the entire process, revealing that, in comparison to the roasting method, this process saves $0.38 per kilogram of spent HDS catalyst, with the advantages of operational simplicity and emission-free. Generally, this study shed new light on the realization of efficient oil removal, with the salience of green, sustainable, and economical.

Comparative life cycle assessment of copper and gold recovery from waste printed circuit boards: pyrometallurgy, chemical leaching and bioleaching

Printed circuit boards (PCBs) make up a substantial amount of electronic waste (e-waste) generated annually. Waste PCBs contain high quantities of copper and gold in comparison to natural ores. As such, “urban mining” of waste PCBs to recover these metals is of commercial interest. In this work, we used life cycle assessment to compare the environmental impact of four copper and gold recovery processes. We evaluated pyrometallurgy, chemical leaching, and bioleaching, as well as a hybrid leaching process that uses bioleaching to recover copper and chemical leaching to recover gold. Furthermore, we considered differences in environmental impact based on differences in electricity sources. If electricity comes from fossil fuels, the pyrometallurgical process results in the lowest environmental impact in all impact categories studied. If electricity comes from carbon-free sources, the pyrometallurgical process results in the lowest environmental impact in all categories studied except global warming, where the hybrid leaching process results in the lowest impact. In all cases, metal recovery from waste PCBs leads to lower environmental impact than primary metal production. Our goal is to guide e-waste recyclers towards more environmentally sustainable metal recovery processes and to provide knowledge gaps in the field to guide future research.

Implementing a sustainable process for the recovery of palladium from spent catalysts at industrial scale: A LCA approach

Due to its unique physicochemical properties, palladium is widely used in several industry applications (e.g., vehicle emission control). In view of the circular economy, it is essential to explore secondary sources of palladium, such as urban mines. Current technologies for effective palladium recovery involve high energy consumption and severe environmental impact. More recently, a novel green method for recovering palladium from spent catalysts through a combination of mild acidic leaching and photodeposition on ZnO nanoparticles was proposed on a laboratory scale. In the present study, the environmental impacts of this recovery method, properly upscaled and modelled, was assessed by employing the LCA approach. Specifically, a comparative LCA was carried out for the process with as well as without recycling key components, such as Cu (II) and NaCl for the leaching solution and ZnO. The outcomes identified critical areas and drove the investigation of alternative process configurations to reduce its environmental footprint, such as the use of carbon dioxide in the photodeposition process with the aim of decreasing the resulting terrestrial ecotoxicity. This study marks a significant step forward in advancing research toward industrial−scale implementation of palladium recovery. It provides valuable insights for researchers in the field of green physicochemical processes for metal recovery, thus offering guidance for future decision−making towards more sustainable practices.

Recent chemical methods for metals recovery from printed circuit boards: A review

AbstractAs the volume of e-waste continues to rise, it is crucial to sustainably manage printed circuit boards (PCBs) and their valuable metal components. PCBs are ubiquitous in modern society, powering a variety of electronic devices. The metal resource crisis and the imperative for a low-carbon circular economy have accelerated the development of e-waste recycling technology. High-value discarded PCBs represent a vital component of e-waste. However, discarded PCBs are deemed hazardous to the ecosystem due to the presence of heavy metals and brominated organic polymers. Thus, recycling metals from discarded PCBs is not only a strategic necessity for fostering a green ecological civilisation but also a crucial guarantee for ensuring a safe supply of mineral resources. This comprehensive review gives the profound details of PCBs, and the performance of and advances in the latest chemical metal recovery methods. Reviewing the latest metal recovery processes, we explored the application of diverse leaching agents, including ionic liquids (ILs), deep eutectic solvents (DESs), organic acids and amino acids. These solvents were assessed in terms of their recovery efficiencies, and most of them demonstrated excellent leaching performance. The role of optimising leaching parameters such as concentration, oxidants, pH, particle size, solid-to-liquid ratios (S/L), temperature, and contact time is underscored, offering insights into achieving sustainable PCB recycling practices. Most of these recent leaching methods successfully extracted base metals (Cu, Fe, Zn, Sn, etc.), as well as precious metals (Au and Ag), achieving leaching efficiencies exceeding 90.0%. Interestingly, their effectiveness can compete with that of traditional hydrometallurgical methods.

Complete recovery of valuable metals from chlorinated titanium-white waste acids: Focus on solvent extraction for recovery and preparation of battery-grade manganese sulfate (MnSO4·H2O) from lab to pilot scale

Chlorination titanium-white waste acid (CTWA) is known to contain a substantial number of valuable metals, including Mn, which can be utilized in the manufacturing of high-value battery cathode materials. Based on the concept of complete resource recovery and zero pollution, a novel process for metal recovery from CTWA has been developed. D2EHPA was used to extract Sc, V from CTWA. Al was completely removed by slowly adding 1.5 mol/L NaOH until the solution pH reached 4.20 and stabilized for 0.5 h. This process resulted in a limited loss of 11 % for Fe and 5 % for Mn. An oxidative precipitation method was proposed to process the Al-free solution to preparate a pure and easily filterable FePO4 product, which can be used in the production of battery materials. Additionally, the loss of Mn in this process was less than 0.5 %. After removing Fe and Al, the pre-extraction feed has an O/A ratio of 2.5:1, a temperature of 40 °C, and an equilibrium pH of 4.5 ∼ 5.0, it is possible to extract Mn at over 99.50 % using a 5-stage extraction. The loaded phase is scrubbed with 5 g/L H2SO4, O/A = 5:1. It is then cyclically stripped with 75 g/L H2SO4, O/A = 8:1, to obtain a battery-grade MnSO4 solution. The stripped solution can be 100 % crystallized to obtain battery-grade MnSO4·H2O products after removing heavy metals using BaS and removing oil with activated carbon. The recovery of Mn in the extraction process was 97.59 %. The pilot test was conducted to demonstrate that the extraction process can be efficiently and continuously produced. The process achieved the recovery of valuable metals from CTWA and the preparation of corresponding products. This process is comprehensive and environmentally friendly, which has an industrial foundation.

Research on the recycling of waste lithium battery electrode materials using ammonium sulfate roasting

Owing to resource limitations, environmental pollution concerns, and the increasing global demand for lithium-ion battery raw materials, the recycling of discarded electrode materials from lithium-ion batteries has emerged as a prominent research area. Nevertheless, among various types of discarded lithium battery electrode materials, limited research has been conducted on the recycling of ternary electrode materials (LiNixCoyMn1-x-yO2). This study proposes an eco-friendly process for the efficient recovery of valuable metals and carbon from mixed materials of discarded ternary lithium-ion battery electrodes. This study investigated the influence of various roasting using ammonium sulfate and leaching conditions on the conversion and extraction rates of valuable metals. Under the condition of a 3:1 mass ratio of ammonium sulfate to lithium battery electrode mixed material, roasting temperature of 450 °C, roasting time of 30 min, liquid-solid ratio of 20:1, leaching time of 20 min, and leaching temperature of 60 °C, the recovery rates of various valuable metals including Li, Ni, Co, and Mn reached 99.99%. For the above process, the chemical control reaction prevailed in the initial 10 min of the roasting reaction, succeeded by the dominance of diffusion control reaction in the subsequent 20 min. In the leaching process, the chemical control reaction governed the first 2 min, succeeded by diffusion control reaction for the next 18 min. Analysis of the reaction's macroscopic and microscopic mechanisms reveals that ammonium sulfate roasting of waste ternary lithium-ion batteries constitutes a typical liquid-solid reaction. In the molten state, NH4+ decomposition releases high-energy H+ ions that break the bonds between metals and oxygen. Consequently, metal atoms from the waste battery's crystal structure combine with ammonium sulfate's sulfate groups, forming various metal sulfates. This paper establishes an eco-friendly process for the efficient recovery of valuable metals by employing the ammonium sulfate roasting method to convert valuable metals in discarded electrode mixed materials into water-soluble sulfates.

Precious Metals Recovery Process from Electronic Boards: Case Study of a Non-Profit Organization (QC, Canada)

The growth in the consumption of electronic products in recent years has resulted in increasing electronic device waste. At the same time, there is a decrease in the availability of raw metals required to produce electronic boards. Recycling through the recovery of precious and critical metals contained in electronic board waste is a solution, but the processes need to be safer for the environment. This paper presents the steps that lead to investment in the development of an eco-friendly and cost-effective process for recovering precious metals from end-of-life electronic telecommunications cards. Social organizations can also become involved in the recycling of electronic cards, thus enabling the integration of marginalized people into society. We examine the case of a non-profit organization whose mission is to help people living with mental health problems through the recycling of end-of-life telecommunication devices. This recycling process must operate within constraints specific to this organization and to the employment of people with mental health issues. The literature review showed that considering ecological and economic factors, the hydrometallurgical process appeared to be a logical choice.

In-situ adsorptive pyrolysis of e-waste using coal and rice husk fly ash as alternative adsorbents for energy and precious metal recovery by solvent extraction

This paper aims to use in-situ adsorptive pyrolysis combined with ultrasonication and solvent extraction for precious metal recovery from e-waste. The pyrolysis of discarded printed circuit board (PCB) and waste cable (WC) resulted in pyrolysis oil yields of 4.2–13.0 and 6.8–13.5%, respectively. Aliphatic and single-ring compounds were the major components of the pyrolysis oil. The pyrolysis char was ultrasonicated at 40 kHz for 20, 30, and 40 min at 35 °C to separate precious metals in pyrolysis char. The amounts of Au and Ag recovered by solvent extraction experiments with 2%vol HCl/2%vol HNO3, 2%vol HNO3 and 2%vol I2/2%vol H2O2 were 36.3–61.4 and 60.7–79.9%, respectively. The total energy recovery from the pyrolysis char, oil, and gas obtained from the pyrolysis of PCB was 9.0–9.2 MJ/kg. These results indicated that in-situ adsorptive pyrolysis with ultrasonication and solvent extraction could potentially facilitate e-waste conversion for energy and metal recovery processes at a lower cost.

An overview of metals extraction and recovery from industrial wastewater sludge

AbstractIndustrial wastewater sludge is one of the vital sources of metals, including heavy metals, valuable metals, and precise metals. Apart from metals' necessity and economic value, some are toxic and harmful to the environment. This review explores the technologies currently applied for extracting and recovering heavy metals from industrial wastewater sludge. The technologies have been explained, and the merits and demerits of methods, as reported in past investigations, have been highlighted. The salient findings of this review are that the hydrometallurgical processes using acid leaching (H2SO4, HNO3, HCl, etc.) have been considered for the metal extraction process. Metal dissolution, concentration/purification, and recovery are the main stages of hydrometallurgical processes. The selection of successive metal recovery methods depends on the concentration of metals and chemical characteristics of industrial wastewater sludge. Different metal purification and concentrations were reported, including adsorption, ion exchange solvent extraction, and so forth, while precipitation and electrodeposition were mainly applied for metal recovery from industrial wastewater sludge. In this review, the cost and economic viability of the metal recovery process are also evaluated by previous reported studies. This review may be considered a valuable source of information for environmentally friendly and cost‐effective methods for metal recovery from industrial wastewater sludge.

Characterization of the effects of acetic acid on the recovery of valuable contents from flotation tailings of non-sulfide metals

Non-sulfide lead flotation tailings draw attention in terms of their valuable contents. Dissolution studies have been carried out with strong inorganic acids, especially in ore form, but these acids have been unfavorable in removal in the context of metal recovery processes. Organic acids, on the other hand, are notable for their environmentally friendly properties and selective metal recovery opportunities. In this study, the effects of acetic acid on metal recovery from oxidized waste were investigated with different experimental parameters at a laboratory scale. Optimal conditions were determined depending on the increase in acetic acid concentration. At 0.75-1.0 M acid concentrations, 49-55% Pb and 49-54% Zn recovery efficiencies were obtained with grades of 7.0-7.2% and 19.5-19.7%, respectively. The recovery of Pb/Zn by the leaching process with acetic acid and the selective non-recovery of iron were also observed through characterization studies. With the Rietveld XRD method, an increase in iron minerals such as goethite and a decrease in smithsonite-hydrozincite minerals were determined. These changes were seen as a decrease in the contents of these minerals in SEM/EDX analysis and as a decrease in smithsonite mineral bond structures in the FT-IR analysis. This study showed that acetic acid has many advantages in the utilization of zinc-lead-containing oxide flotation tailings, which have high economic value, such as selective metal recovery, easy biodegradability, environmental friendliness, and non-corrosiveness.

Study on metal recovery process and kinetics of oxidative leaching from spent LiFePO4 Li-batteries

A green environmental protection and enhanced leaching process was proposed to recover all elements from spent lithium iron phosphate (LiFePO4) lithium batteries. In order to reduce the influence of Al impurity in the recovery process, NaOH was used to remove impurity. After impurity removal, the spent LiFePO4 cathode material was used as raw material under the H2SO4 system, and the pressure oxidation leaching process was adopted to achieve the preferential leaching of lithium. The E-pH diagram of the Fe-P-Al-H2O system can determine the stable region of each element in the recovery process of spent LiFePO4 Li-batteries. Under the optimal conditions (500 r·min–1, 15 h, 363.15 K, 0.4 MPa, the liquid-solid ratio was 4:1 ml·g–1 and the acid-material ratio was 0.29), the leaching rate of Li was 99.24%, Fe, Al and Ti were 0.10%, 2.07% and 0.03%, respectively. The Fe and P were precipitated and recovered as FePO4∙2H2O. The kinetic analysis shows that the process of high-pressure acid leaching of spent LiFePO4 materials depends on the surface chemical reaction. Through the life cycle assessment (LCA) of the spent LiFePO4 whole recovery process, eight midpoint impact categories were selected to assess the impact of recovery process. The results can provide basic environmental information on production process for recycling industry.

Recent Advancements in Pyrolysis of Halogen-Containing Plastics for Resource Recovery and Halogen Upcycling: A State-of-the-Art Review.

Plastic waste has emerged as a serious issue due to its impact on environmental degradation and resource scarcity. Plastic recycling, especially of halogen-containing plastics, presents challenges due to potential secondary pollution and lower-value implementations. Chemical recycling via pyrolysis is the most versatile and robust approach for combating plastic waste. In this Review, we present recent advancements in halogen-plastic pyrolysis for resource utilization and the potential pathways from "reducing to recycling to upcycling" halogens. We emphasize the advanced management of halogen-plastics through copyrolysis with solid wastes (waste polymers, biomass, coal, etc.), which is an efficient method for dealing with mixed wastes to obtain high-value products while reducing undesirable substances. Innovations in catalyst design and reaction configurations for catalytic pyrolysis are comprehensively evaluated. In particular, a tandem catalysis system is a promising route for halogen removal and selective conversion of targeted products. Furthermore, we propose novel insights regarding the utilization and upcycling of halogens from halogen-plastics. This includes the preparation of halogen-based sorbents for elemental mercury removal, the halogenation-vaporization process for metal recovery, and the development of halogen-doped functional materials for new materials and energy applications. The reutilization of halogens facilitates the upcycling of halogen-plastics, but many efforts are needed for mutually beneficial outcomes. Overall, future investigations in the development of copyrolysis and catalyst-driven technologies for upcycling halogen-plastics are highlighted.

Gold Recovery from Thiosulfate Leaching Solution Using Silicon Powder and Electrochemical Monitoring of Its Process

Gold recycling from Waste Electrical and Electronic Equipment (WEEE) has been actively conducted. We previously reported a noble metal recovery process using aqua regia and electroless displacement deposition onto silicon powder [1,2]. Using silicon powder has such advantages as that noble metals and copper are selectively recovered, and sawdust silicon, that is, industrial waste silicon powder is available to use. Recently, ammonium thiosulfate solution has attracted attention as a safe and low-cost solution for gold leaching [3-6]. In this study, we successfully recovered gold from an ammonium thiosulfate solution by using silicon powder [7,8], and tried to monitor the recovering behavior electrochemically. Since the ammonium thiosulfate leaching solution includes copper ions as oxidizing agent, copper is recovered by silicon powder. Thus, the monitoring was conducted in order to determine the suitable timing for efficiently obtaining pure gold during the process. For experimentation, an ammonium thiosulfate solution containing gold(I) sulfite and copper(II) sulfate was prepared (pH = 13). We immersed a gold wire in the solution and measured the rest potential during the recovery process using silicon powder. The potential of gold wire shifted stepwise toward negative direction at each start and end of gold and copper recovery. The results suggest that the efficient recovery of high-purity gold can be achieved by monitoring the potential of gold.[1] K. Fukuda, S. Yae, N. Fukumuro, S. Sakamoto, and H. Matsuda, ECS Trans., 53(19), 69 (2013). DOI: 10.1149/05319.0069ecst[2] K. Fukuda, N. Fukumuro, S. Sakamoto, and S. Yae, ECS Trans., 61(10), 1 (2014). DOI: 10.1149/06110.0001ecst[3] M.G. Aylmore and D.M. Muir, Miner. Eng., 14, 135 (2001). DOI: 10.1016/s0892-6875(00)00172-2[4] H. Arima, T. Fujita, and W. Yen, Mater. Trans., 43, 485 (2002). DOI: 10.2320/matertrans.43.485[5] S. Syed, Hydrometallurgy, 115-116, 30 (2012). DOI: 10.1016/j.hydromet.2011.12.012[6] B. Xu, W. Kong, Q. Li, Y. Yang, T. Jiang, and X. Liu, Metals, 7, 222 (2017). DOI: 10.3390/met7060222[7] Y. Iwai, Y. Takashima, A. Matsumoto, and S. Yae, Abst. Interfinish2020 20th world congress, P-E2-001 (2021).[8] Y. Takashima, A. Matsumoto, Y. Iwai, S. Arita, and S. Yae, J. Surf. Finish. Jpn., 73, 98 (2022). DOI: 10.4139/sfj.73.98

Determination of potential replacement of natural carbon raw materials with walnut waste in the reduction process of metal recovery

x

Selective electrodeposition of Co-Ni alloys from synthetic quasi LiB NMC 532 cathode sulphate solutions using rotating plate potentiostatic electrowinning

The interest in recycling spent lithium-ion batteries (Li-ionB) has surged due to the rising demand for valuable metals (e.g., Co, Ni, Li and Mn) and concerns about environmental repercussions emanating from conventional battery waste disposal. This research is centered on the recovery of the valuable Ni-Co alloys from synthetic Ni, Co, Mn and Li sulphate solutions mimicking the NMC 532 ratio of elements using a hydro-electrometallurgy process route that integrates hydrometallurgy and potentiostatic electrometallurgy techniques. This quasi-model is done to elucidate the effect of multiple influencing parameters, through isolation and varying, on the selective electrodeposition of Co-Ni from multi-ion (Li, Ni, Mn and Co) complex solutions before applying it using real cathode leachates. The selective electrowinning metal recovery process route is a cost-effective alternative to the energy, cost and material-intensive hydrometallurgy intermediate purification processes such as solvent extraction, selective precipitation, and ion-exchange. The study delves into the effects of various electrowinning parameters, including applied potential, temperature, pH, Co, Ni, Na2SO4, NaH2PO4 buffer concentration, and cathode rotational speed. These parameters were thoroughly investigated and effectively optimised to achieve the recovery of 98.2% pure Ni0.65Co0.35 at a rate of 0.060 g/cm2.h with an impressive 89.25 % current efficiency. The composition of the electrowon deposit was meticulously quantified using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and subjected to analysis through a Scanning Electron Microscope (SEM-EDS). Additionally, the phase composition was evaluated using X-Ray Diffraction analysis (XRD). The results successfully demonstrate the technical feasibility of recovering Ni-Co alloys, yielding high quantities of industrial-grade pure Ni-Co alloys. This comprehensive electro-hydrometallurgical process, designed for both closed and loop recycling purposes, promotes a more environmentally preservative approach to recycling spent lithium-ion battery cathode material. The approach contributes significantly to the development of sustainable resource management infrastructure.

Copper and chromium removal from industrial sludge by a biosurfactant-based washing agent and subsequent recovery by iron oxide nanoparticles

Industrial wastewater treatment generates sludge with high concentrations of metals and coagulants, which can cause environmental problems. This study developed a sequential sludge washing and metal recovery process for industrial sludge containing > 4500 mg/kg Cu and > 5000 mg/kg Cr. The washing agent was formulated by mixing glycolipid, lipopeptide, and phospholipid biosurfactants from Weissella cibaria PN3 and Brevibacterium casei NK8 with a chelating agent, ethylenediaminetetraacetic acid (EDTA). These biosurfactants contained various functional groups for capturing metals. The optimized formulation by the central composite design had low surface tension and contained relatively small micelles. Comparable Cu and Cr removal efficiencies of 37.8% and 38.4%, respectively, were obtained after washing the sludge by shaking with a sonication process at a 1:4 solid-to-liquid ratio. The zeta potential analysis indicated the bonding of metal ions on the surface of biosurfactant micelles. When 100 g/L iron oxide nanoparticles were applied to the washing agent without pH adjustment, 83% Cu and 100% Cr were recovered. In addition, X-ray diffraction and X-ray absorption spectroscopy of the nanoparticles showed the oxidation of nanoparticles, the reduction of Cr(V) to the less toxic Cr(III), and the absorption of Cu. The recovered metals could be further recycled, which will be beneficial for the circular economy.

Process simulation and techno-economic evaluation of recovery of metals and alumina from spent hydroprocessing catalysts using leaching with EDTA

In this work, simulation and techno-economic performance evaluation of a metal recovery process are performed using SuperPro Designer® simulation software. The aim is to simulate the recovery of metals, including molybdenum, vanadium, nickel, and alumina (Mo, V, Ni, and Al), present in spent hydroprocessing catalysts. The catalysts are usually discarded as solid wastes from the petroleum refining industries. The metal recovery process layout has been developed with reasonable assumptions and optimum reaction conditions that are carried out for hydrotreating (HDT) spent catalysts using EDTA as a leaching agent. The simulation process design included economic performance evaluation, the total cost of investment, unit production cost, internal rate of return, net present value, and project payback time, which gives promising results to utilize EDTA as an efficient metal recovery process.

Techno-economic analysis of an integrated bio- and hydrometallurgical process for base and precious metal recovery from waste printed circuit boards

Electronic waste (e-waste) is one of the fastest-growing waste streams and is often referred to as an urban mine due to its high base and precious metal content. Printed circuit boards (PCBs) have been the focus of numerous studies investigating bio- and hydrometallurgical pathways to extract and recover metals of value. This study evaluated the economic feasibility of an integrated bio- and hydrometallurgical process for extracting and recovering base and precious metals from PCBs. The process consisted of collecting and processing PCBs, extracting and recovering base metals using biogenic sulfuric acid and ferric iron, and extracting and recovering precious metals using hydrometallurgical pathways. A preliminary techno-economic analysis (TEA) was conducted to examine the potential costs of a plant that can process 1,000 tons per year of PCBs in Australia. The key factors that influence the economic feasibility were identified, and the effects of various factors, such as process efficiencies and market conditions, on the plant's profitability were evaluated. This assessment provided insight into the economic aspects of the process and assisted in identifying critical research pathways. Based on this analysis, the proposed process is profitable under optimised conditions and can address many challenges associated with e-waste processing in Australia.

Catalytic recovery of metals from end-of-life polycrystalline silicon photovoltaic cells: Experimental insights into silver recovery

A steady increase in end-of-life (EoL) polycrystalline silicon photovoltaic (c-Si PV) panels is necessitating the development of recycling technologies to guarantee sustainable environmental management and a circular economy. Herein, we propose a comprehensive EoL c-Si PV recycling strategy with an emphasis on selective silver (Ag) recovery. Primarily, a combination of physical and thermal treatment led to the isolation of PV cell fraction from the EoL PV module. Thereafter, a less-toxic, sulphuric acid-hydrogen peroxide (1 M H2SO4- H2O2 1% (v/v %)) lixiviant was used for Ag leaching at 70 °C. A novel catalytic process using platinum-embedded activated carbon (Pt/AC) was used with only hydrogen gas and air to recover selectively and concentrate the Ag+ from the synthetic PV cells leachate. Finally, pure metallic silver (Ag > 99.0 %) was obtained by the conventional electrowinning process. This study also proposes an explicit recovery process for Al, Cu, and Si. In addition, the Pt/AC catalytic process could efficiently recover Cu from the PV cells, similar to Ag. Following the complete recovery of Ag and Cu through Pt/AC, there is sufficient scope to isolate other metals like Al and Pb leaving behind crude Si wafers. Hence, the as-proposed recycling and metal recovery process is a newer approach benefiting industrial implementation.

A multi-stage volatilization and condensation process for green and efficient recovery of valuable metals from High-Sb crude Sn

Circulation of Sb in an Sn refining system strongly affects the production process. In this study, an innovative multi-stage vacuum separation process was developed and successfully applied on an industrial scale. Our results indicate that Sn–Sb alloys can be completely separated by vacuum evaporation. In this study, we used single-factor experiments to investigate the effects of distillation temperature and time on several factors, such as the Sn content in the residue, Sb content in the volatile matter, separation rate, and direct recovery rate of Sb from high-Sb crude Sn. The purity of the obtained Sn and Sb products was above 99%, and the recovery rate of the metal was above 99% under the optimal distillation conditions of 1673 K and 150 min. In addition, we suggest that Sn volatilization occurs due to the presence of SbSn intermetallic compounds. A two-stage vacuum-separation process for high-Sb crude Sn was developed for industrial production. Continuous production data showed that the direct yields of Sn and Sb were 72.99% and 71.15%, respectively. The total power consumption of this process was as low as 1086 kWh/t, which is better than the corresponding parameters of other treatment processes.