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[Display omitted] • Co-recycle of spent automotive catalysts and printed circuit boards was proposed. • Co-recycle can simultaneously achieve metal enrichment and detoxification. • Slag design, pollution suppression, metal distribution and settlement were analyzed. • Influence of copper size on platinum group metals recovery rate was discussed. The traditional pyrometallurgical recycling of nano-sized platinum group metals (PGMs) from spent automotive catalysts (SACs) is an energy-intensive process that requires the addition of large quantities of copper capture and slag-forming reagents. Similarly, pyro-recycling of valuable metals from waste printed circuit boards (WPCBs) is also an energy- and reagent-intensive process that and carries a risk of pollution emissions. Based on the complementarity of composition and similarity of recycling process, synergistic pyro-recycling of SACs and WPCBs allow copper in WPCBs to capture PGMs in SACs and oxides from two waste form slag jointly, which offers benefits of enhanced metal recovery, reduced reagent and energy consumption, and suppressed pollutant emissions. However, the mechanisms of PGMs capture and pollutant transformation in co-smelting remain unknown. Here, we investigated the sub-processes mechanisms of slag formation, brominates fixation, multi-metal distribution and kinetic settlement. Oxides in both wastes support SiO 2 -Al 2 O 3 -CaO slag formation with low melting point and viscosity, where CaO suppresses the emission of brominated pollutants. Copper (50–100 μm) from WPCBs facilitates nano-sized PGMs in SACs recovery through capture and settlement. The results of demonstration experiments indicated a recovery rate of 94.6 %, 96.8 %, 97.2 %, and 98.1 % for Cu, Pt, Pd, and Rh, respectively, with a debromination efficiency exceeding 98 %. The theoretical analysis provides support for the establishment of a synergistic pyro-recycling process for SACs and WPCBs and provides insights into the potential for a greener and more efficient co-recycling of multi urban mines. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rapid development of stretchable electronics made by circuits, microchips, and encapsulation elastomers has caused the production of a large amount of electronic waste (e‐waste). The degradation of elastomers can highly minimize the negative effects of e‐wastes. However, chemicals that included acid, alkali, and organics were repeatedly used during the recycling process, which were environmentally unfriendly. Here, a water‐modulation‐degradation‐reconstruction (WDR) polyvinylpyrrolidone (PVP)‐honey composite (PHC) polymer‐gel was developed and could be regarded as encapsulation elastomers to realize a fully recyclable water‐degradable stretchable (WS) electronics with multi‐functions. The stretchability of the PHC polymer‐gel could be modulated by the change of its water retention. The Chip‐integrated liquid metal (LM) circuits encapsulated with the modulated PHC encapsulation elastomer could withstand a strain value of ~3000%. Moreover, we developed a WS biomedical sensor composed of PHC encapsulation elastomer, LM circuits, and microchips, which could be fully recycled by biodegrading it in water to reconstruct a new one. As before, the reconstructed WS biomedical sensor could still simultaneously realize the combination of ultra‐stretchability, recycling, self‐healing, self‐adhesive, and self‐conformal abilities. The results revealed that this study exercises a profound influence on the rational design of multi‐functional WS electronics. [ABSTRACT FROM AUTHOR]

Light‐emitting diodes (LED) are widely used for energy savings. A lot of different materials and especially metals are needed to produce LED. End‐of‐life LED contain critical metals like indium or rare earth elements. In this study, first a thermochemical step is used to recover the critical metal indium from LED with hydrochloric acid‐containing vapor from polyvinyl chloride as chlorine source. Then, the LED residue is leached with sulfuric acid and hydrogen peroxide. From the leachate, the heavy rare earth element lutetium can be extracted with n‐octanol and tributyl phosphate. [ABSTRACT FROM AUTHOR]

The ever‐increasing importance of critical metals (CMs) in modern society underscores their resource security and circularity. Waste‐printed circuit boards (WPCBs) are particularly attractive reservoirs of CMs due to their gamut CM embedding and ubiquitous presence. However, the recovery of most CMs is out of reach from current metal‐centric recycling industries, resulting in a flood loss of refined CMs. Here, 41 types of such spent CMs are identified. To deliver a higher level of CM sustainability, this work provides an insightful overview of paradigm‐shifting pathways for CM recovery from WPCBs that have been developed in recent years. As a crucial starting entropy‐decreasing step, various strategies of metal enrichment are compared, and the deployment of artificial intelligence (AI) and hyperspectral sensing is highlighted. Then, tailored metal recycling schemes are presented for the platinum group, rare earth, and refractory metals, with emphasis on greener metallurgical methods contributing to transforming CMs into marketable products. In addition, due to the vital nexus of CMs between the environment and energy sectors, the upcycling of CMs into electro‐/photo‐chemical catalysts for green fuel synthesis is proposed to extend the recycling chain. Finally, the challenges and outlook on this all‐round upgrading of WPCB recycling are outlined. [ABSTRACT FROM AUTHOR]

The traditional craft villages in Vietnam in general and in Bac Ninh province in particular have been exposing many negative impacts on the environment. The heavy metal-rich wastes from the metal recycling casting craft villages in the field of metal recycling and metal casting are causing severe heavy metal pollution not only to the air, soils, and sediments but also to the groundwater resources. In Da Hoi iron recycling craft village in Chau Khe ward, Tu Son town, Bac Ninh province, Vietnam, the Holocene aquifer is exposed to the Ngu Huyen Khe River's sediments contaminated with heavy metals Lead, Cadmium, Nickel, and Zinc. Freundlich isotherm parameters of the Holocene aquifer have been selected for finite element modeling of heavy metal transport with high temporal and spatial varying retardation factors to get reliable quantitative heavy metals' distribution in depth and time. Initial and boundary conditions have been augmented to be established. The retardation factors of the advection and dispersion transport in the Holocene aquifer for heavy metals Pb, Zn, Cd, and Ni are very highly none-linear and very much varying in time and space: 8.7–66.4 for Pb, 2.0–12 for Zn, 1.7–4.8 for Cd and 1.1–5.9 for Ni. The results of the numerical modeling show that heavy metal transport in the Holocene aquifer is very fast and the entire aquifer thickness has equilibrium aquifer formation and aquifer water heavy concentrations after around 2–2.5 years for Cd and Ni, around 4 years for Zn and around 27 years for Pb. The heavy metals' fluxes from the Holocene aquifer to the Pleistocene aquifer are maximal and more or less constant from the equilibrium time and would cause severe contamination of the Pleistocene aquifer. [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]

One of the main causes of atmospheric pollution comes from mobile sources that emit noxious gases from internal combustion engines. For the suppression of toxic exhaust gases, a catalytic converter is used as an anti-pollution device, because it catalyzes or accelerates the degradation of emissions making them less harmful. In the catalytic converter, platinum (Pt), palladium (Pd) and rhodium (Rh) catalysts are normally used for their excellent performances. However, these metals are expensive, rare, and scarce in the earth's crust. These precious metals thus emphasized the importance of developing efficient recycling practices. For the recycling of these precious metals, a very fast, easy, economical, environmentally friendly and high-safety electric pulse discharge method was used to separate the Pd and Rh from the spent metal-honeycomb (MH) catalytic converter consisting of p as the catalyst carrier. To standardize the precious metals recycling process and attain the highest level of separation of Pd and Rh, electric pulse shots ranging from 120-240 and standoff distances (gap width between the positive electrode and the sample surface) ranging from 5-10mm were applied. During this process, an electrical explosion occurred within the honeycomb structures through the electric shock. After the electrical explosion, the particles are collected, then sieved and physical characterizations are performed. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX) analyses revealed that the most separated particles are highly pure, and dispersed homogeneously without destroying particle structures. In this article, we first report about 87.91% of Pd and 90.77% of Rh are separated from each catalytic converter using the electric pulse discharge method that can overcome challenges and achieve ambitious recycling targets in the recycling industry. The effects of the discharge energies and the shock energy determined by varying electric pulse shots and standoff distance, respectively, are discussed. These findings provide insight into the recovery of precious metals for electric pulse discharge and play a role in developing a very effective recycling method not only for the catalytic converter but also for other devices. [ABSTRACT FROM AUTHOR]

A restorative process, where the nonmetallic fraction from e-waste printed circuit boards is reused as a raw material for the conformation of a new polymer matrix composite with increased properties favoring its industrial applications, is proposed with a zero residues approach. Low density polyethylene pellets and nonmetallic fraction particles were mixed, and due to the generation of static electricity during the mixing process, the nonmetallic particles became attached to the polyethylene pellets; the blended material was fed into a screw extruder, producing filaments of the new composite. Mechanical properties increased as the particles content increased, presenting an ultimate tensile strength going from 20 for the raw low-density polyethylene to more than 60 MPa, and a yield strength that goes from 10 to 50 MPa on the composite with 6.0 wt.% particles. Also, the flammability of the composite improved, reducing its linear burning rate and increasing the time between detachment of two consecutive drops. Nonmetallic fraction particles were oriented in the extrusion direction and had a good adhesion with the polyethylene matrix. These composites can be employed for the production of prototypes using additive manufacture. [ABSTRACT FROM AUTHOR]

Hydrometallurgical bioprocesses for base metal recovery in environmentally friendly electronic device waste (e-waste) recycling are typically studied under neutral pH conditions to avoid competition between metals and hydrogen ions. However, metal leachate is generally strongly acidic, thus necessitating a neutralisation process in the application of these bioprocesses to e-waste recycling. To solve this pH disparity, we focused on acid-tolerant bacteria for metal recovery under strongly acidic conditions. Four acid-tolerant bacterial strains were isolated from neutral pH environments to recover base metals from simulated waste metal leachate (pH 1.5, containing 100 or 1000 mg L−1 of Co, Cu, Li, Mn, and Ni) without neutralisation. The laboratory setting for sequential metal recovery was established using these strains and a reported metal-adsorbing bacterium, Micrococcus luteus JCM1464. The metal species were successfully recovered from 100 mg L−1 metal mixtures at the following rates: Co (8.95%), Cu (21.23%), Li (5.49%), Mn (13.18%), and Ni (9.91%). From 1000 mg L−1 metal mixtures, Co (7.23%), Cu (6.82%), Li (5.85%), Mn (7.64%), and Ni (7.52%) were recovered. These results indicated the amenability of acid-tolerant bacteria to environmentally friendly base metal recycling, contributing to the development of novel industrial application of the beneficial but unutilised bioresource comprising acid-tolerant bacteria. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste copper sulphate solution was electrolyzed to provide sulphuric acid. • This study obtained leaching rates of 93 % of Ni, 91 % of Co, 89 % of Mn and 92 % of Li. • Recovery rates of 91 % of Ni, 91 % of Co, 86 % of Mn and 90 % of Li were achieved. • A novel method was developed without using any acid or reductant. • This work demonstrated the application of treating waste with waste. Effective recovery of Li, Co, Ni and Mn from cathode materials of spent lithium-ion batteries (LIBs) has become a global concern. In this study, electrolysis of copper sulfate to produce sulfuric acid and electrons were utilized to recover Li, Co, Ni and Mn from spent LIBs. The obtained results showed that 93 % of Ni, 91 % of Co, 89 % of Mn and 94 % of Li were leached and 99 % of Cu was deposited during leaching process by adopting the 0.225 mol/L of copper sulfate with a solid/liquid ratio of 15 g/L at a current density of 50 mA/m2 and 80 °C for 4.5 h. Then, a current efficiency of 72 % for the cathode and 30 % for the anode was achieved at a current density of 40 mA/m2, 70 °C and pH 2.5 during electrodeposition process. The Ni-Co deposition followed the principle of anomalous codeposition and the complete deposition time of Co, Ni and Mn were 3 h, 9 h and 10 h, respectively. Eventually, the Ni, Co, Mn, Li and Cu can be recovered as Ni-Co alloy, MnO 2 and Li 2 CO 3 and Cu metals with the corresponding recovery rates of 99.40 %, 91.00 %, 90.68 %, 85.59 % and 89.55 %, respectively. This study proposes a promising strategy for recycling cathode materials from spent LIBs without addition of chemical reductants and acids. [ABSTRACT FROM AUTHOR]

In the previous decade, organic aqua regia (OAR) was discovered as a mixture of pyridine and thionyl chloride that has been observed to surprisingly yet notably selectively dissolve precious metals, dissolution‐resistant gold. Given the novel combination is two common organic solvents, it has immense potential to contribute to a circular economy of metal recycling, economically and environmentally. The underlying mechanisms behind its metal dissolution and interesting properties are not well‐understood. Using both the original mixture and derivatives, the role of each OAR reagent was analyzed in the dissolution of gold to begin probing and illuminating the novel mechanism. Three mechanisms were proposed: radical based, oxidant and ligand, and Lewis acid and base. Computational means were used to propose possible mechanisms. Experiments were used to explicate the possible mechanisms. Discoveries from the original publication were used to verify assessments and suggest future areas of study for further confirmation. Based on the finding that 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) does not significantly affect the amount of gold dissolved, the radical mechanism was dismissed. Findings from experiments replacing pyridine with its derivatives disproved the likelihood of the oxidant and ligand mechanism. Finally, with the support of proton nuclear magnetic resonance (1H NMR) and other characterization techniques, the Lewis acid and base mechanism was determined to be the most probable mechanism of OAR. The mechanistic findings reported herein will pave the way for continued understanding of the mechanism to be exploited and optimized for other metals and organometallic chemistry in the recycling of metals. [ABSTRACT FROM AUTHOR]

Liquid multiphase systems (MPS) have gained attention in recent years due to their versatility for catalytic processes. This review article presents a critical discussion of the most recent advances on the utilization of MPS in both homogeneous and heterogeneous metal‐catalysed reactions. Pros and cons of some exemplificative multiphase configurations are highlighted and compared to conventional methods in single liquid solvents. The application of MPS for the implementation of strategies for the upgrading of biobased molecules is also examined with emphasis on process intensification and sustainability including the catalyst/products separation and the in‐situ recycle and reuse of the metal catalysts. These aspects are analyzed with a view on expanding MPS applications and whenever possible, explore scale‐up opportunities. [ABSTRACT FROM AUTHOR]

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]

Ni and Co elements in superalloy scraps are scarce metal resources in China, and recycling these metal elements has great environmental and economic significance. This present study proposes a novel and efficient recycling process for the recovery of nickel and cobalt elements from superalloy leaching solution. The superalloy leaching solution reacted with NaOH solution to obtain precipitates. Then, the precipitates were mixed with Na2CO3 and roasted at high temperature. After sodium roasting, Al and Cr elements were removed by water leaching to obtain pure NiO and CoO as raw materials for preparing ternary precursors. As the nuclear part of this process, the impacts of sodium roasting on the water leaching behaviors of Al and Cr elements from Ni and Co sediments was investigated. Under suitable conditions of sodium roasting, the leaching efficiencies of Al and Cr elements are 99.11% and 99.39%. Moreover, the promoting mechanism of sodium roasting on leaching of Al and Cr elements was discussed from the view of phase composition. [ABSTRACT FROM AUTHOR]

Machine vision technique is gaining popularity in metal scraps recycling process due to the increasing need for automation and the relatively low cost of industrial camera. Relative movement between camera and scraps within camera exposure time will inevitably cause image motion blur and influence the separation accuracy. In this study, a novel deblurring prior for camera-conveyor system was proposed and applied to a metal separation system. Key performance indicators, like trajectory stability, separation distance, and separation accuracy, were analyzed and compared between blurred-case separation and deblurred-case separation. The results indicated that by applying the proposed deblurring algorithm, the Peak Signal-to-Noise Ratio (PSNR) value of all the blurred images increased, the average PSNR value of all the 31 blurred images is 27.71 and that of the deblurred images is 29.51. Objects center coordinates shift shows a significant decrease after the deblurring process. A higher conveyor speed may increase the separation efficiency, but will cause the decrease of separation accuracy and separation purity. The scraps motion trajectory obtained from deblurred cases is much more stable, which implies a stable landing point of scraps, and by applying the proposed deblurring algorithm, the separation accuracy increases from 82.9 to 88.0%, and separation purity increases from 90.7 to 93.6%. [ABSTRACT FROM AUTHOR]

Leaching solutions of printed circuit boards (PCBs) contain noble and base metal ions. The precious metal ions present in the leaching solutions of PCBs could be separated by cementation with copper metal. After recovery of precious metal ions by cementation, the filtrate contains Cu(II) together with base metal ions like Al(III), Fe(III), Fe(II), Ni(II), Sn(II), and Zn(II). In this work, separation experiments were conducted to recover Cu(II) and Ni(II) from the filtrate. First, copper ions were completely separated from the filtrate by chemical reduction with hydrazine at the following conditions: a molar ratio of 8 for hydrazine to Cu(II), 20°C, 500 rpm, and 20 mins. By adding sodium oxalate to the solution after separation of Cu(II), most of the Ni(II) and 38% of the Zn(II) were co-precipitated at 20°C, 60 mins, 500 rpm, and a molar ratio of 20 for sodium oxalate to nickel. After dissolving the coprecipitates of Ni(II) and Zn(II) oxalates in a 0.5 M HCl solution, the Zn(II) was completely removed from the solution by a five-stage cross-current extraction with 2.5 M Cyanex 272. Nickel hydroxides were then recovered from the raffinate by precipitation with NaOH. The purity of the copper metal and nickel hydroxides was higher than 99%. A process was proposed to recover Au(III), Pd(II), Cu(II), and Ni(II) from the leaching solutions of PCBs. [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 recycling of cathode materials for spent NCM has always been a major concern for the energy industry. However, among the current processing methods, the general leaching efficiency of Li is between 85% and 93%, with much room for improvement. The recovery of Ni, Co and Mn requires a high cost of secondary purification. In this study, to recycle the NCM cathode material, a route of sulphated reduction roasting – selective Li water leaching – efficiency acid leaching of Ni, Co, Mn – extraction separation – crystallisation was adopted. The results showed that after roasting (a temperature of 800 °C, a reaction time of 90 min, a carbon content of 26%, and a sulphuric acid addition of nH2SO4:nLi = 0.85), Li water leaching efficiency was 98.6%, followed by acid leaching of Ni, Co and Mn at around 99%. Mn, Co were extracted with Di-(2-ethylhexyl) phosphoric acid and 2-Ethylhexyl phosphonic acid mono-2-ethylhexyl ester respectively to obtain Ni, Co, Mn solutions, which eventually were crystallized for manganese sulphate, cobalt sulphate, lithium carbonate and nickel sulphate products, with high purity of 99.40%, 98.95%, 99.10%, and 99.95%. The results of this study improved the leaching efficiency of Li and were closely linked to the actual industrial preparation of Ni, Co and Mn sulphates, providing a feasible and promising basis for spent NCM cathode materials industrial recovery. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) as a new-generation of solvents are receiving increasing attention as environmentally friendly solvents in various analytical techniques. These solvents are new generation solvents, and based upon what they are derived from, they can be the safest, cheapest, and most effective extraction methods available. With DES, the extraction efficiency and metal ion recycling are significantly improved. In this work, the potential application of these solvents for the extraction of Pb(II) ions was investigated. For that purpose, hydrophobic DESs (HDESs), based on L-menthol as H-acceptor and decanoic acid as H-donor, were prepared at molar ratios of acceptor to donor of 1:1 and 1:2. In the optimized extraction procedure, the Pb(II) ions were extracted into the organic phase with the efficiency of 94.3% and 97.3% for 1:1Men:DecA and 1:2 Men: Dec A, respectively. The results also showed that unlike of classical liquid-liquid extraction methods, in the original solutions, counterions are not required to transfer the analyte to the hydrophobic phase. Furthermore, no ligands were required to transfer the analyte ions to the HDES phase: the results show that the extraction efficiency of 1:1 HDES decreased to 88.65% in the presence of 18C6, and to 96.5% for 1:2 HDES. Comparable results for HDES (1:1 Men: DecA) extraction efficiency in the proposed method with the efficiency of 1,2- dichloroethane and chloroform in classical methods (96.7% and 92%, respectively), without counterions and without the requirement for ligands as carriers, make this HDES-based extraction method simpler, less expensive, and most importantly, more environmentally friendly. [ABSTRACT FROM AUTHOR]

Copyright of BHM Berg- und Hüttenmännische Monatshefte is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A residue containing TiO2 and PGMs is generated in the hydrometallurgical process used for recycling platinum-group metals (PGMs). In this study, a pyrometallurgical process was considered in which PGMs from the residue generated in the hydrometallurgical process were concentrated in a molten copper phase as a collector metal and TiO2 was separated into the SiO2-CaO-TiO2 slag phase with SiO2 and CaO flux. The dissolution of PGMs must be reduced to minimize the loss of PGMs to the slag. Therefore, the distribution ratios of Pt as representative PGMs between the liquid SiO2-CaO-Al2O3-TiO2 or liquid SiO2-CaO-TiO2 slag and molten copper were measured at 1773K under an oxygen partial pressure of pO2 = 10-10. The experimental results showed that the distribution ratio of Pt increased with TiO2 concentration in the slag, and the distribution ratio of Pt reached a maximum value at a TiO2 concentration of approximately 10 mass%, and decreased with a further increase in TiO2 concentration with the SiO2-CaO-Al2O3-TiO2 slag. However, as TiO2 concentration in the slag increased, the distribution ratio of Pt decreased with the SiO2-CaO-TiO2 slag. Additionally, the experimental results showed that the distribution ratio of Pt between the SiO2- CaO-Al2O3-TiO2 slag and liquid copper increased with the slag basicity B, defined as B = (mass%CaO)/(mass%SiO2) when the TiO2 concentration in the slag was greater than 10 mass%. [ABSTRACT FROM AUTHOR]

Recycling metals from waste materials has become a major approach to metal resource utilization, with electronic waste (e‐waste) and waste catalysts being the most important recycling resources. Although traditional recovery technologies (pyrometallurgy and hydrometallurgy) have a recovery efficiency of up to 100%, they have disadvantages of high energy consumption, high cost, and strong corrosiveness. Most importantly, they cannot achieve selective leaching. To address these issues, some fusion technologies have been developed. Electrodeposition has significant advantages in separating and purifying each metal, but if applied on a large scale in industry, it requires higher energy consumption. While photocatalytic technology has low energy consumption but low selectivity, hence further exploration is needed. Metal‐organic frameworks (MOFs) materials have great selectivity for metal ions, which are environmentally friendly and efficient, and a promising new material. Some recently typical recovery methods for six valuable metals, platinum (Pt), gold (Au), silver (Ag), lithium (Li), nickel (Ni), and cobalt (Co) in e‐waste and industrial catalysts are reviewed. The advantages and disadvantages of each method as well as their impact on the leaching efficiency and selectivity of different metals are also compared, aiming to provide useful guidance for further continuously advancing the research on efficient, selective, environmentally friendly metal recycling in the future. [ABSTRACT FROM AUTHOR]

The noble metals, owing to their unique properties, find extensive applications in various modern industries. However, as non-renewable resources, the reserves of noble metals in the natural environment are limited. Therefore, recovering noble metals from discarded industrial waste not only helps alleviate the challenges of noble metal resource scarcity, but also addresses environmental pollution. Herein, the state-of-the-art techniques for noble metal recovery are divided into two categories, pyrometallurgy and hydrometallurgy, in which the conversion mechanisms are discussed. The pyrometallurgy strategies depend primarily on high-temperature smelting reduction, while the hydrometallurgy strategies are segmented into leaching, enrichment and extraction, showing enormous development potential in the future. The novel exploration of noble metal pyrometallurgical extraction is briefly reviewed. The solvolysis, photochemistry, and electrochemistry-initiated approaches for noble metal recycling from secondary resource are summarized in detail. Finally, the future challenges and development prospects of sustainable noble metal recovery are discussed. This work offers a summary of current recovery methods for noble metals and provides a reference for resource utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] Although cobalt nitride (CoN)-based nanomaterials have been widely designed as advanced oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR) catalysts, the continuous consumption of lithium-ion batteries (LIBs) has led to a high price of cobalt metal. Therefore, in the future, recycling valuable Co elements from spent devices and boosting their service efficiency will inevitably promote the utilization of Co-based materials in water splitting and zinc-air batteries (ZABs). Herein, we realize the Co recycling from spent LIBs by a simple hydrometallurgy method. Under the assistance of hexamethylenetetramine and polystyrene spheres, after the hydrothermal and pyrolysis treatment in the NH 3 atmosphere, the as-reclaimed cobalt oxalates were successfully transformed into novel three-dimensional (3D) CoN nanoflowers (denoted as CoN NFs). Benefiting from the unique 3D flower-like architectures, intrinsic high conductivity, large surface area, uniformly dispersed CoN nanoparticles, and the synergistic effect between Co 3 N and CoO phases, the 3D flower-like CoN NFs exhibited excellent OER catalytic activity. The performance was much better than commercial RuO 2 in the 1.0 M KOH solution. Furthermore, the CoN NFs-based water splitting cell needed a voltage of 1.608 V to achieve the current density of 10 mA cm−2, which is even 16 mV smaller than that of Pt/C||RuO 2 benchmark (1.624 V). Meanwhile, the CoN NFs-derived ZAB exhibited a high peak power density of 107.3 mW cm−2 (vs. 103.2 mW cm−2 of Pt/C-RuO 2 -based ZAB) and a low charge–discharge voltage gap (0.93 V vs. 1.43 V of Pt/C-RuO 2 -based ZAB). Due to the excellent structural and elemental stabilities, the corresponding water splitting cell and ZAB had outstanding durability. This work successfully explored an advanced industrial chain from recycling Co metal in spent devices to designing the high-efficiency HER/OER/ORR electrocatalysts for advanced water splitting devices and ZABs. This will further promote the value-added utilization of valuable Co metal in various energy storage or conversion devices. [ABSTRACT FROM AUTHOR]

Transition and rare earth metals serve as indispensable raw materials across a broad spectrum of technological applications. However, their utilization is frequently linked to substantial waste production. Consequently, the recycling and recovery of these metals from end-of-life products or metal-contaminated aqueous environments hold significant importance within the framework of a circular economy. In our investigation, we employed synthetic mesoporous silica monoliths, synthesized via the sol–gel method and functionalized with chelating groups, for the efficient recovery of metal ions from aqueous matrices. The monoliths were characterized using a multi-technique approach and were tested in the recovery of paramagnetic Gd3+, Cu2+ and Co2+ ions from aqueous solutions, using 1H-NMR relaxometry to evaluate their uptake performance in real time and under simple conditions. Detailed information on the kinetics of the capture process was also highlighted. Finally, the possibility to regenerate the solid sorbents was evaluated. [ABSTRACT FROM AUTHOR]

Sustainable battery recycling is essential for achieving resource conservation and alleviating environmental issues. Many open/closed-loop strategies for critical metal recycling or direct recovery aim at a single component, and the reuse of mixed cathode materials is a significant challenge. To address this barrier, here we propose an upcycling strategy for spent LiFePO4 and Mn-rich cathodes by structural design and transition metal replacement, for which uses a green deep eutectic solvent to regenerate a high-voltage polyanionic cathode material. This process ensures the complete recycling of all the elements in mixed cathodes and the deep eutectic solvent can be reused. The regenerated LiFe0.5Mn0.5PO4 has an increased mean voltage (3.68 V versus Li/Li+) and energy density (559 Wh kg–1) compared with a commercial LiFePO4 (3.38 V and 524 Wh kg–1). The proposed upcycling strategy can expand at a gram-grade scale and was also applicable for LiFe0.5Mn0.5PO4 recovery, thus achieving a closed-loop recycling between the mixed spent cathodes and the next generation cathode materials. Techno-economic analysis shows that this strategy has potentially high environmental and economic benefits, while providing a sustainable approach for the value-added utilization of waste battery materials. Direct recycling of critical battery materials bring promise but a challenge for the mixed cathode chemistries. Here, the authors report a sustainable upcycling approach, transforming degraded LiFePO4 and Mn-rich cathodes into a high-voltage polyanionic material with an increased energy density and economic value. [ABSTRACT FROM AUTHOR]

The recovery of valuable metals from spent lithium‐ion batteries using deep eutectic solvents (DESs) is an environmentally and economically beneficial process. In this study, a method has been developed for recovering LiNi0.33Co0.33Mn0.33O2. Our process operates under mild conditions and with a little oxalic acid as a reducing agent, dissolving lithium, cobalt, manganese, and nickel completely utilizing a DES that is composed of tetrabutylammonium chloride and of monochloroacetic acid. Lithium and nickel were selectively precipitated using oxalic acid. Cobalt and manganese were precipitated as oxalates by adding an oxalic acid aqueous solution. Finally, the DES can be regenerated by evaporating the water. Importantly, valuable metals can be recovered with a 100 % yield through the process of DES recycling. This environmentally friendly and recyclable process is suitable for the recycling of spent lithium‐ion batteries industry. [ABSTRACT FROM AUTHOR]

The rapid identification and classification of metal garbage has been experimentally investigated. By combining laser-induced breakdown spectroscopy (LIBS) and machine learning, metal garbage can be effectively identified through spectral analysis. In this work, a novel method for metal garbage classification was developed, and a LIBS system was self-developed. As an example of metal recycling, five types of metal were adopted. Several characteristic lines of Al, W, Fe, Cu, Sn, Pb, and C were identified. For a more effective classification, principal component analysis was conducted to reduce the dimension of the spectra. Samples after the dimension reduction were classified by using K-nearest neighbors, and five types were obtained, exhibiting a final classification accuracy of 97.18%. Moreover, a mathematical model of the linear formulas between spectrum and concentration was established to achieve quantitative analysis with Fe taken as an example, laying the foundation for more refined classification. [ABSTRACT FROM AUTHOR]

A novel synergistic extractant consisting of a deep eutectic solvent (DES) and tri‐n‐butyl phosphate (TBP) is proposed for selective extraction of valuable metals from waste lithium‐ion batteries (LIBs). The extraction efficiencies of Ni2+, Co2+, and Mn2+ were 99.8%, 99.1%, and 95.9%, respectively, and high‐purity Li+ was enriched in the raffinate after the single‐stage extraction. Valuable metal salts, lithium carbonate (92.3 wt%) and cobalt oxalate (94.9 wt%), were obtained. The DES + TBP extractant retained its high extraction performance even after multiple regeneration cycles. The extraction process followed the so‐called "cation exchange mechanism" with thermodynamic properties of ΔH < 0, ΔG < 0, and ΔS < 0. The molecular‐level extraction mechanism demonstrated that the extraction process was dominated by both electrostatic and coordination interactions between the metal ions and DES/TBP, based on quantum chemical calculations. This study aims to provide a new strategy for recycling valuable metals from waste LIBs. [ABSTRACT FROM AUTHOR]

With the rapidly changing business environment, the dynamic capability of an enterprise begins with sensing and grasping technology opportunities. Considering that the knowledge gaps between science and technology hinder the exploration of technology opportunities, previous studies proposed methods to extract technology opportunities by identifying the knowledge gaps between science and technology literature. This study improves upon previous methods for identifying knowledge fields contained in the literature by introducing a deep learning-based clustering approach. This study also proposes a way to reduce experts' workloads in determining gaps in the field between science and technology literature. The key idea of the proposed method is to include technologies other than the technology in question. Additionally, pyrolysis technology can convert plastic wastes into useful materials and is considered a green technology. Therefore, this study applies our improved method to explore the technology opportunities of pyrolysis technology. The results show that our method can effectively identify technology opportunities. In the case of plastic wastes, the results show that recovering carbon fibers from plastic wastes and recycling metals from e-waste plastics are expected to be prevailing technological fields. [ABSTRACT FROM AUTHOR]

Wave energy, as a significant renewable and clean energy source with vast global reserves, exhibits no greenhouse gas or other pollution during real-sea operational conditions. However, throughout the entire lifecycle, wave energy convertors can produce additional CO2 emissions due to the use of raw materials and emissions during transportation. Based on laboratory test data from a wave energy convertor model, this study ensures consistency between the model and the actual sea-deployed wave energy convertors in terms of performance, materials, and geometric shapes using similarity criteria. Carbon emission factors from China, the European Union, Brazil, and Japan are selected to predict the carbon emissions of wave energy convertors in real-sea conditions. The research indicates: (1) The predicted carbon emission coefficient for unit electricity generation ( E F co 2 ) of wave energy is 0.008–0.057 kg CO2/kWh; when the traditional steel production mode is adopted, the E F co 2 in this paper is 0.014–0.059 kg CO2/kWh, similar to existing research conclusions for the emission factor of CO2 for wave energy convertor (0.012–0.050 kg CO2/kWh). The predicted data on carbon emissions in the lifecycle of wave energy convertors aligns closely with actual operational data. (2) The main source of carbon emissions in the life cycle of a wave energy converter, excluding the recycling of manufacturing metal materials, is the manufacturing stage, which accounts for 90% of the total carbon emissions. When the recycling of manufacturing metal materials is considered, the carbon emissions in the manufacturing stage are reduced, and the carbon emissions in the transport stage are increased, from about 7% to about 20%. (3) Under the most ideal conditions, the carbon payback period for a wave energy convertor ranges from 0.28 to 2.06 years, and the carbon reduction during the design lifespan (20 years) varies from 238.33 t CO2 (minimum) to 261.80 t CO2 (maximum). [ABSTRACT FROM AUTHOR]

Gallium (Ga), indium (In), and germanium (Ge) play an important role in the modern high-tech material field. Due to their low content and scattered distribution in the crust, and the increasing demand for these metals in recent years, their supply risks have sharply increased. Therefore, the recycling of these metals is of great significance. In this work, a systematic review was performed using the Web of Science, Scopus, MDPI, Elsevier, and Springer Link databases. The combined terms used for the search were Ga/In/Ge, extraction, separation, and recycling. After a careful evaluation of the titles, abstracts, and full texts, a total of 106 articles were included. This paper briefly describes the resource features of Ga, In, and Ge. After that, the chemical principles, technical parameters, and metal recovery in various extraction and separation methods from monometallic and polymetallic resources are systematically reviewed. Leaching followed by solvent extraction or ion exchange is the main process for Ga, In, and Ge recovery. Although many attempts have been made to separate multiple metals from leaching solutions, highly selective solvents and resins are still the research priority. This review can provide theoretical and technical guidance for the separation of Ga, In, and Ge from various resources. [ABSTRACT FROM AUTHOR]

Molten gallium trichloride emerges as a promising solvent for oxidative metal recycling. The use of supercritical fluid enhances the performance and kinetics of metal dissolution due to significantly lower viscosity in the reaction media. Additionally, the dual molecular nature of gallium trichloride, existing as edge-sharing ES-Ga2Cl6 dimers at low temperatures and high pressure, or flat trigonal GaCl3 monomers in the vicinity of the critical point and low pressures, creates the possibility to tailor the chemical geometry to a particular metallic species. Nevertheless, the mechanism of dimer dissociation, local structure, and atomic dynamics in supercritical gallium trichloride fluids are not known. Using first-principles molecular dynamics, validated by comparison with our high-energy X-ray diffraction results, we illustrate the elementary steps in dimer dissociation. These include the formation of intermediate corner-sharing CS-Ga2Cl6 dimers, the partial disproportionation of GaCl3 monomers at high temperatures and low pressures, changes in the local environment of molecular entities, and unusual atomic dynamics in supercritical fluids. [ABSTRACT FROM AUTHOR]

Cuprous sulfide constitutes the primary component of copper concentrate and matte. Due to copper's sulfur-affinity characteristics, achieving one-step separation and recovery of copper and sulfur has always posed a challenge in copper metallurgy. Deep eutectic solvents (DESs) have emerged as environmentally friendly electrolytes for the separation and recycling of metals and their compounds. This study demonstrates the feasibility of dissolving Cu2S, reducing it to copper (Cu), and oxidizing it to sulfur (S) through electrolysis in Reline DES. Optimised electrolysis conditions of 1.2 V, 80 °C, and 6 hours result in the deposition of pure nano-sized copper particles, ranging from 100–200 nm, and the production of sulfur particles with an average size of around 5 μm. The crystalline structure of the anode product is identified as S12 and S6. When Cu2S is introduced into Reline, it dissolves [CuCl2]− without disrupting the structure of the choline ion (Ch+). Furthermore, a kinetic study reveals that higher temperatures promote the redox processes of [CuCl2]− Cu and S2− to S, enhancing the overall reaction rates. Additionally, the diffusion coefficient (D) of [CuCl2]− increases with rising temperatures. [ABSTRACT FROM AUTHOR]

We use the stellar fossil record to constrain the stellar metallicity evolution and star-formation histories of the post-starburst (PSB) regions within 45 local PSB galaxies from the MaNGA survey. The direct measurement of the regions' stellar metallicity evolution is achieved by a new two-step metallicity model that allows for stellar metallicity to change at the peak of the starburst. We also employ a Gaussian process noise model that accounts for correlated errors introduced by the observational data reduction or inaccuracies in the models. We find that a majority of PSB regions (69 per cent at >1σ significance) increased in stellar metallicity during the recent starburst, with an average increase of 0.8 dex and a standard deviation of 0.4 dex. A much smaller fraction of PSBs are found to have remained constant (22 per cent) or declined in metallicity (9 per cent, average decrease 0.4 dex, standard deviation 0.3 dex). The pre-burst metallicities of the PSB galaxies are in good agreement with the mass–metallicity (MZ) relation of local star-forming galaxies. These results are consistent with hydrodynamic simulations, which suggest that mergers between gas-rich galaxies are the primary formation mechanism of local PSBs, and rapid metal recycling during the starburst outweighs the impact of dilution by any gas inflows. The final mass-weighted metallicities of the PSB galaxies are consistent with the MZ relation of local passive galaxies. Our results suggest that rapid quenching following a merger-driven starburst is entirely consistent with the observed gap between the stellar mass–metallicity relations of local star-forming and passive galaxies. [ABSTRACT FROM AUTHOR]

Li, Ni and Co elements in ternary lithium-ion batteries are rare metal resources in China, and recycling these metal elements has a great environmental and economic significance. In this work, a clean selective leaching method for Li, Ni, Co and Mn elements from ternary lithium-ion battery waste was proposed. The mixed positive and negative electrode powders were activated by anaerobic roasting at different temperatures and times. Then, the roasted samples were leached in citric acid under the same conditions. Under suitable roasting conditions, the leaching efficiencies of Li, Ni, Co and Mn are 99.93%, 95.25%, 97.22% and 99.94%. The leaching efficiency of Cu is < 1%, which realizes the selective leaching of metal elements in the ternary lithium-ion battery waste. Moreover, the promoting mechanism of anaerobic roasting on leaching of metal elements in spent lithium-ion batteries was discussed from the view of material structure and phase composition. [ABSTRACT FROM AUTHOR]

Recycling precious metals with high-efficiency is undoubtedly beneficial to optimize resource utilization for environmental remediation and sustainable development. Herein, we report an efficient route to recycle the palladium (Pd) and platinum (Pt) electrocatalysts using a phase transfer method. This strategy involves acidic dissolution of deactivated precious metal (Pd/Pt) electrocatalysts from their loading substrates, mixing with an ethanolic solution of dodecylamine (DDA), subsequent extraction of metal ions into a non-polar organic phase, and final reduction by sodium borohydride to reproduce high-performance electrocatalysts towards typical electrochemical reactions, e.g., oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR). In specific, the transfer efficiencies are up to 98% and the final recovery rate is over 85% for Pd and Pt electrocatalysts in each cycle. This approach symbolizes a facile and efficient way to recover precious metals, which might be applied to recycling a wide range of metals in various realms after appropriate modifications. [ABSTRACT FROM AUTHOR]

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Hydrometallurgy recycling of heavy metals from electroplating sludge is of hot spot in recent decades. Such recycling was tedious in the separation of impure Fe/Al prior to heavy metals from acid leachate after sludge dissolution. Herein, a facile hydrothermal route was developed to separate Fe/Al from Cu-bearing leachate. The results showed that when the leachate was directly hydrothermally treated at 160 °C in the presence of nitrate and ethanol, Al/Cu were stable in the leachate, but nearly 100% Fe was removed as hematite nanoparticles. With the addition of chloridion, the removal efficiencies of Fe/Al/Cu did not change apparently, but the corresponding precipitate was akageneite, not hematite. By replacing chloridion with sulfate, nearly 100% Fe and 98.6% Al were separated as natrojarosite/natroalunite block, while the Cu loss was only 1.7%. However, with the supplementary of phosphate, the Fe/Al removal achieved nearly 100%, but the Cu removal also achieved by 92.6%. The thermodynamic analysis showed that Cu was precipitated rapidly via the phosphate/Cu oxyhydroxide route by adding phosphate but removed slightly via the coordination route on the Fe/Al precipitates with the addition of nitrate, chloridion, and sulfate. In summary, Fe was effectively separated as hematite, akageneite, natrojarosite, and phosphate halite, in the presence of nitrate, chloridion, sulfate, and phosphate, separately. But the removal of Al as natroalunite and AlPO4 only started by adding sulfate and phosphate, respectively. Such results enabled a short hydrometallurgy process to effectively recycle heavy metals from electroplating sludge. [ABSTRACT FROM AUTHOR]

[Display omitted] • The evolution and speciation of chlorine during ASR pyrolysis are studied. • Org-chlorine can be converted to InO-chlorine and remain in char. • Up to 12% and over 64% of chlorine are migrated to HCl and char, respectively. • Rising temperature promotes the conversion from Org-chlorine to inorganic in char. • Calcium-based compounds in ASR play a predominant role in the capture of chlorine. Disposal of automobile shredder residue (ASR) via pyrolysis enables the recovery of valuable products; however, the production of hazardous pollutants and low-value products is inevitable due to its high chlorine content. In this work, chlorine evolution behavior and the conversion mechanism during ASR pyrolysis between 480 and 600 °C were systematically studied. The experimental results for organic chlorine (Org-Cl) showed that released chlorinated gases were complex, and HCl only accounted for 35% of the gas phase products, while short-chain hydrocarbons with carbon atoms between two and four accounted for 52%. Chlorine was predominantly retained in the char, and Org-Cl was the primary contributor to the residual chlorine, accounting for over 50% of the char. The content of inorganic chlorine (InO-Cl) was low in the raw sample but significantly increased in the char. Through the distinction between organic and inorganic chlorine content in char, it was confirmed that Org-Cl could be converted to InO-Cl due to complex secondary reactions with metallic compounds. The conversion was favored by increasing the Org-Cl content and the temperature. Our findings clarified the evolution mechanism of chlorine and the transformation from Org-Cl to InO-Cl, thus providing guidance for chlorine regulation and the efficient recycling of metal resources. [ABSTRACT FROM AUTHOR]

The recycling of heavy metals contained in alkaline batteries allows minimizing the environmental impact and gives an alternative use to this waste, which can be used in the pyrometallurgical industry. In the present research work, we evaluated the possibility of reducing the manganese oxide black mass from discarded alkaline batteries to produce metallic manganese, using charcoal as a reducing agent. The procedure begins with the characterization of the raw materials, the stoichiometric calculations and the preparation of a practical method to produce self-reducing pellets, composed of manganiferous material, charcoal and bentonite as agglomerant. Computer simulations were performed, to establish the appropriate thermodynamic conditions for reduction. The tests were carried out in a tubular-type furnace, and the results obtained were evaluated using optical microscopy, scanning electron microscopy coupled with microchemical analyses and X-ray diffraction techniques. It was verified that the agglomerates showed a self-reducing behavior, so an increase of the %Mn in the samples due to increasing the temperature of the reduction treatment was found, as well as the presence of a metallic manganese phase that was identified by X-ray diffraction analysis. Flow sheet for the production of self-reducing pellets containing eucalyptus charcoal for the recycling of manganese contained in spent alkaline batteries [ABSTRACT FROM AUTHOR]