Extraction Of Valuable Metals Research Articles

A review of comprehensive utilization of red mud.

Red mud (RM) is a solid waste generated during the process of alumina production. RM has already posed a serious environmental threat with the development of the alumina refining industry. The comprehensive utilization of RM has attracted much attention due to its large-scale generation and harmful nature. This paper introduces the characteristics and state of RM and summarizes the relevant research on the comprehensive utilization of RM. The results show that comprehensive utilization of RM is mainly focused on the preparation of building materials, the extraction of valuable metals, catalyst synthesis and environmental protection. Besides, the article discusses the existing problems while utilizing RM. Prospects and suggestions for different utilization methods of RM are proposed.

Comprehensive extraction of valuable metals from waste ternary lithium batteries via roasting and leaching: Thermodynamic and kinetic studies

Considering the existing problems in the extraction of waste ternary materials, a method of reduction roasting - sulfuric acid leaching is proposed in this paper. The waste ternary battery material is mixed with carbon powder, reduced and roasted in an argon atmosphere to destroy the original crystal lattice of the ternary material, adjust the valuable metal ions to a valence state suitable for leaching, and reduce the difficulty of leaching. Moreover, recycling waste lithium batteries were systematically studied from the thermodynamic and kinetic aspects. Thermodynamic calculations indicate that the theoretical temperature for reduction roasting is 500–650 °C, and the roasting products are composed of lithium carbonate, nickel, cobalt, nickel oxide and manganese oxide, which has been confirmed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy analysis. The activation energy for the reduction roasting of the cathode material was calculated as 134.7 kJ/mol by thermogravimetry–differential scanning calorimetry and Kissinger formula. The roasted electrode materials were subjected to an acid leaching process. The effects of roasting and leaching conditions on the metal extraction from waste ternary batteries were investigated based on thermodynamic calculations, and the following optimal conditions were identified: 10% carbon content, 600 °C roasting temperature, 120 min roasting time, 2 mol/L sulfuric acid concentration, 85 °C leaching temperature, 10:1 liquid-to-solid ratio and 60 min leaching time. The extraction of lithium, nickel, cobalt, and manganese reached 98.3%, 97.2%, 98.8%, 96.1%, respectively, under the optimal conditions. The kinetic analysis of the acid leaching process adopted the shrinking core model and Arrhenius formula. The activation energies of lithium, nickel, cobalt, and manganese leaching were 23.9 kJ/mol, 25.2 kJ/mol, 23.0 kJ/mol, and 27.6 kJ/mol, respectively, which indicates that acid leaching is an internal diffusion control process. This study provides an economical and efficient process route and lays a theoretical and technological foundation for the extraction of cathode materials from waste ternary batteries.

Microwave-assisted chlorination extraction of valuable metals from spent power ternary lithium-ion batteries

ABSTRACT In the present study, a combined process of microwave-assisted chlorination roasting-water leaching was developed to efficiently extract metal ions from spent ternary lithium-ion batteries. Polyvinyl chloride (PVC) was used as chlorine source to generate HCl for chlorination reaction. Activated carbon was first selected as the optimal absorbing medium material. Subsequently, spent anode graphite was used to induce carbonisation reduction reaction with spent LiNixCoyMnzO2 (NCM) to promote recovery of valuable metals. The characterisations of X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and thermodynamic analysis indicated that HCl derived from PVC pyrolysis could spontaneously react with carbonisation reduction products from spent NCM to form the corresponding water-soluble metal chloride for the effective recovery of valuable metals. Under the optimal conditions with reaction temperature at 450°C, material mass ratio PVC:NCM of 4:1, reaction time at 60 min and microwave power at 500 W, 96.43% of Li, 95.51% of Ni, 95.27% of Co and 95.43% of Mn can be recovered, respectively. The leaching kinetics can be described by the Avrami equation with surface chemical reaction controlled, and the leaching activation energies of Li, Ni, Co and Mn were 36.32, 42.31, 38.84 and 41.96 kJ∙mol−1, respectively. This microwave-assisted method might provide a new route for the effective recycling of spent lithium-ion batteries by chlorinated metallurgical processes.

High-yield recycling and recovery of copper, indium, and gallium from waste copper indium gallium selenide thin-film solar panels

A separation process for Cu, In, Ga, and Se (CIGS)-based thin-film solar panels is proposed in this study. Initially, the separation process, by peeling off the panels in a layer-by-layer manner, was achieved by utilizing the different thermal strains of materials inside the CIGS solar panels. Subsequently, the recovery process was performed by annealing the CIGS layers for the removal of Se, and then leaching was performed with nitric acid, followed by the individual extraction of valuable metals. The pH values, concentrations of extractant, stripping agents, organic-aqueous ratios, and reaction time were investigated in detail to optimize the separation conditions for Cu, In, and Ga. First, In was extracted using di-(2-ethylhexyl) phosphoric acid into the organic phase, while Cu and Ga remained in the aqueous phase, by controlling the extraction conditions. After the extraction of In, Ga was extracted using the same extraction agent under different conditions, and nearly pure Cu remained in the residual aqueous solution. Ammonium hydroxide was added to three solutions to form metal hydroxide precipitates. Under the optimal conditions, a recovery rate of >90% could be achieved for In, Ga, and Cu. Furthermore, all as-formed hydroxides were recycled and converted into metal oxides with a purity of >99% by calcination. These findings can provide a pathway for the effective recycling and recovery of Cu, In, and Ga from waste CIGS thin-film solar panels. • A facile and practical method to separate and recover valuable metals respectively from the real commercial thin-film solar panel was demonstrated. • A novel and low-cost physical separation process was induced to peer off the solar panel layer by layer via the extremely low-temperature liquid nitrogen treatment. • An extraction and stripping process was designed to separate Cu, In, and Ga from a complicated multi-element system individually. • Highly pure valuable metal oxides were recovered as the final products, establishing a possible curcular economy model for waste solar panel recycling and recovery.

Recent advances in the approaches to recover rare earths and precious metals from E‐waste: A mini‐review

AbstractIn the present day, with the rapid rate of advancements in technology, gadgets become obsolete very fast. The chase to keep up with the latest technologies diminishes the gadget's lifespan considerably. Consequently, they are discarded within a short time after their production, resulting in electronic waste (E‐waste) being the fastest growing waste stream globally, with an annual production rate of 2.44 million short tonnes. The metals present in such E‐waste provide several attractive properties, rendering them crucial in several applications as components of electronic and electrical devices. The major roadblock faced by mankind today is an effective technology with high recovery, low cost, and minimal environmental impact to recycle such electronic waste. In this mini‐review, we elucidate the various recycling routes for metal extraction from waste and recent advances in the same. We have attempted to highlight the recent trends adopted by various researchers to recycle and extract valuable metals and rare earths from E‐waste. Finally, the challenges and prospects in the extraction of rare earths and precious metals for E‐waste research have been clearly brought out and suggestions have been made for future work.

Extraction of valuable metals from acidic wastewater and blast furnace slag by a collaborative utilization process

AbstractTwo typical wastes, acidic wastewater and titanium‐bearing blast furnace slag, are generated in the smelting process of vanadium‐titanium magnetite. Generally, the acidic wastewater is neutralized by lime or limestone and titanium‐bearing blast furnace slag is directly stacked in the tailings pond, which not only pollutes the ecological environment but also causes the waste of metal resources. In this study, a collaborative utilization process for efficient extraction of titanium, iron, magnesium, and aluminum from acidic wastewater and low titanium‐bearing blast furnace (LTBBF) slag was proposed. At the leaching temperature of 80°C, the leaching time of 50 min, and the liquid–solid ratio of 9:1, 99.26% Ti, 99.47% Mg, and 99.45% Al could be extracted from LTBBF slag by acidic wastewater. Leaching residue mainly composed of Ca and Si could be used as silicon fertilizer. The Ti in the leaching solution could be separated by adding Na3PO4. The precipitation efficiency of Ti reached 98.53% under the molar ratio of Na3PO4 to TiO2 of 1.4, reaction temperature of 85°C, and reaction time of 40 min. The titanium phosphate ((TiO)2P2O7) was obtained by calcination of the precipitate at 900°C for 3 h. Adding oxalic acid to the filtrate above, the precipitation efficiency of Fe, Mg, and Mn reached 96.47%, 99.21%, and 99.45%, respectively, under the optimal conditions, while the precipitation efficiency of Al was only .38%. By adjusting the pH of the filtrate to 6.5, 99.83% Al could be precipitated as Al(OH)3, and the final solution was evaporated to obtain Na2SO4 products. The method proposed realizes the harmless treatment of acidic wastewater and LTBBF slag and recovers the metal resources in both of them.

Accessing Metals from Low-Grade Ores and the Environmental Impact Considerations: A Review of the Perspectives of Conventional versus Bioleaching Strategies

Mining has advanced primarily through the use of two strategies: pyrometallurgy and hydrometallurgy. Both have been used successfully to extract valuable metals from ore deposits. These strategies, without a doubt, harm the environment. Furthermore, due to decades of excessive mining, there has been a global decline in high-grade ores. This has resulted in a decrease in valuable metal supply, which has prompted a reconsideration of these traditional strategies, as the industry faces the current challenge of accessing the highly sought-after valuable metals from low-grade ores. This review outlines these challenges in detail, provides insights into metal recovery issues, and describes technological advances being made to address the issues associated with dealing with low-grade metals. It also discusses the pragmatic paradigm shift that necessitates the use of biotechnological solutions provided by bioleaching, particularly its environmental friendliness. However, it goes on to criticize the shortcomings of bioleaching while highlighting the potential solutions provided by a bespoke approach that integrates research applications from omics technologies and their applications in the adaptation of bioleaching microorganisms and their interaction with the harsh environments associated with metal ore degradation.

Heavy Metal, Waste, COVID-19, and Rapid Industrialization in This Modern Era—Fit for Sustainable Future

Heavy metal contamination, waste, and COVID-19 are hazardous to all living things in the environment. This review examined the effects of heavy metals, waste, and COVID-19 on the ecosystem. Scientists and researchers are currently working on ways to extract valuable metals from waste and wastewater. We prefer Tessier sequential extraction for future use for heavy metal pollution in soil. Results indicated that population growth is another source of pollution in the environment. Heavy metal pollution wreaks havoc on soil and groundwater, especially in China. COVID-19 has pros and cons. The COVID-19 epidemic has reduced air pollution in China and caused a significant reduction in CO2 releases globally due to the lockdown but has a harmful effect on human health and the economy. Moreover, COVID-19 brings a huge amount of biomedical waste. COVID-19’s biomedical waste appears to be causing different health issues. On the other hand, it was discovered that recycling has become a new source of pollution in south China. Furthermore, heavy metal contamination is the most severe ecological effect. Likewise, every problem has a remedy to create new waste management and pollution monitoring policy. The construction of a modern recycling refinery is an important aspect of national waste disposal.

Selective Chlorination and Extraction of Valuable Metals from Iron Precipitation Residues

Due to the aggravating situations regarding climate change, resource supply, and land consumption by the landfilling of residual materials, it is necessary to develop recycling processes that allow the recovery of valuable metals from industrial residues with significantly reduced CO2 emissions. In this context, it is conceivable that processes using chlorination reactions will be of importance in the future. The simultaneous selective chlorination and evaporation of nine valuable metals was evaluated theoretically and experimentally in small-scale STA trials; then, it was tested practically on six different iron precipitation residues from the zinc and nickel industries. The metal chlorides FeCl3∙6H2O and MgCl2∙6H2O were identified as the most effective reactants, resulting in high extraction rates for the metals In, Ag, Zn, Pb, Au, and Bi, while lower yields are achievable for Sn, Cu, and Ni. Iron, which is predominant in volume in the residual materials, shows lower chlorination tendencies which allows the effective separation of the valuable elements of interest from the iron containing matrix.

Innovative bio-acid leaching method for high recovery of critical metals from end-of-life light emitting diodes

The main objective of this work is to introduce a new green recycling process for recovering valuable metals from electronic waste. One of the fastest-growing electronic waste streams is end-of-life light emitting diodes (LEDs). Due to environmental risk and a worldwide shortage of metals, recycling and recovering their valuable metal is an urgent task. In this study, an innovative bio-hydrometallurgical method for the extraction of valuable metals from end-of-life LED lamps is proposed. The present study evaluated a direct multi-step regulation strategy of waste content to enhance the bio-acid leaching of LED at a high pulp density (40 g/L) using a culture of sulfur-oxidizing bacteria Acidithiobacillus thiooxidans (A. thiooxidans). Through a step-wise feeding strategy (10 g/d), the extraction of the metal was further improved due to balancing of A. thiooxidans population and stabilization of pH, ORP, and sulfuric acid concentration in the bioleaching solution. By comparing the results of multi-step and one-stage contact bioleaching, with multi-step contact bioleaching, Cu, Ni, and Ga extraction yields increased from 67%, 92%, and 39% to 100%, 100%, and 75%. Furthermore, this study demonstrates that the presence/addition of EPS did not only adsorb metal ions but also increased diffusion barriers, thus diminishing metal ion transfer from LED into bioleaching solution for an extended period of time. The multi-step non-contact bio-acid leaching method enhanced strategic critical element leaching yields to 100% from end-of-life LEDs. The final product, enriched in Au and Ag, could be used as a secondary source of precious metals.

Regeneration of high-performance Li1.2Mn0.54Ni0.13Co0.13O2 cathode material from mixed spent lithium-ion batteries through selective ammonia leaching

The efficient recycling process of spent lithium-ion batteries (LIBs) to regenerate electrode materials can alleviate the metal resources scarcity and environmental pollution. Here, the Li-rich cathode Li1.2Mn0.54Ni0.13Co0.13O2 (LR) material was successfully re-synthesized via an environment-friendly and impurity-free recycling process combined ammonia leaching with sol-gel process. Compared with the general methods, ammonia leaching is delicately applied to selectively extract valuable metals from spent LiNixCoyMnzO2 materials exclusive of other impurities (Fe, Al). The process facilitates the subsequent recovery without additional purification process. Surprisingly, the leaching efficiency of Li, Ni, and Co elements is up to as high as 99.28%, 99.63%, and 99.76%, respectively. After adding extra metal compounds stoichiometrically, LR with uniform particle size and elements distribution was regenerated from the valuable metals in the lixivium via the sol-gel method. The LR synthesized at 800 °C exhibits a satisfying capacity of 246.5 mAh g−1 at 0.1 C and high-stable cycle performance with a capacity of 163.3 mAh g−1 after 80 cycles at 0.2 C between 2.0 and 4.8 V. The fundamental results provide inspiration for recovery of the complex spent LIBs, which can selectively separate the multiple metal impurities with high-efficient reutilization.

An experimental comparison: Horizontal evaluation of valuable metal extraction and arsenic emission characteristics of tailings from different copper smelting slag recovery processes

This study comprehensively investigated arsenic's enrichment, distribution, and characteristics in tailings. XRD and SEM-EDS characterized the phase and morphology of tailings from various smelting processes. At the same time, the embedding characteristics of arsenic in the ore phase were analyzed by EPMA. The differences between arsenic's leading ore phase carriers in different recovery processes were found. It was discussed that this phenomenon would be related to the element-binding ability and the precipitation priority of the ore phase. The occurrence state of arsenic was discussed by sequential chemical extraction experiments. The proportion of leachable arsenic is higher than the low-risk limit, whatever which smelting method is adopted, which leads to high environmental risk. In the experiment of comparing the leaching toxicity of tailings by different leaching methods, the arsenic concentration in the leaching solution of tailings recovered by the flotation method exceeds the specified safety range. Although the tailings after reduction smelting did not show high leaching toxicity, a large number of accumulations also would not represent absolute safety.

Research on Separation and Extraction of Valuable Metals from Complex Non-ferrous Metals Resources by High Pressure Oxygen Leaching Methodology: A Review

Research on Separation and Extraction of Valuable Metals from Complex Non-ferrous Metals Resources by High Pressure Oxygen Leaching Methodology: A Review

Simultaneous Separation and Recovery of Gold and Copper from Electronic Waste Enabled by an Asymmetric Electrochemical System.

Exploiting efficient strategies for the selective separation and extraction of valuable metals from e-waste is in urgent demand to offset the ever-increasing depletion of metal resources, satisfy the sustainable supply of metal resources, and reduce the environmental impact from toxic metals. Herein, an asymmetric electrochemical system, constructed by polyaniline (PANI) nanofibers grown on carbon cloth (CC) and CC as the respective counter and working electrodes, is presented for the simultaneous and selective extraction of gold and copper from e-waste leachate solution. Harnessing the established CC/PANI//CC system, CC/PANI as the anode electrode is capable of selectively and rapidly extracting gold with high efficiency, accompanied by excellent reusability. Meanwhile, cathodic CC electrode is found to achieve almost 100% recovery of copper at a voltage of -1.2 V. Furthermore, the feasibility of the proposed asymmetric electrochemical system is further exemplified in waste central processing unit (CPU) leaching solution, enabling to recover simultaneously gold and copper with high purity. This work will provide meaningful guidance for simultaneous separation and recovery of multiple valuable metals from real e-waste.

The Recycling of Coal Fly Ash: A Review on Sustainable Developments and Economic Considerations

The recycling and utilization opportunities for coal fly ash (CFA) have increased in the past two decades. However, limited commercialization of the material is still reported, while disposal and management remain major concerns. CFA utilization is currently commercially feasible in the building and construction industry. Other alternative uses that are being explored involve the extraction of valuable metals and the purification of wastewater. The CFA-produced adsorbent material utilized in wastewater purification processes should be able to generate water that meets the legal quality requirements for reutilization in alternative applications. On the other hand, in the recovery of metallic components such as smelter-grade alumina, high recovery and high purity products are only achievable through the processing of CFA using expensive and energy—intensive processes. Furthermore, most of the current CFA recycling processes tend to generate secondary solid residues (SSR), which can cause environmental pollution, thus requiring further downstream processing. In this context, this paper reviews and discusses current research on CFA recycling methods, challenges and opportunities associated with resource recovery from CFA, and the acceptability of the value-added products, and it therefore proposes sustainable processes for CFA utilization. This review further suggests that to successfully compete with bauxite for production of smelter-grade alumina, other saleable value-added products such as Ti, Fe and the REEs should be recovered by engineering an integrated process design. The generated SSR in each process must also be characterized, recycled and re-used to reduce waste production and advance the circular economy concept. The review concludes that for CFA to become considered as a more attractive commercial resource, there is need for its complete and holistic utilization in high volumes and in different applications to offset its low value.

A Novel Deep-Eutectic Solvent with Strong Coordination Ability and Low Viscosity for Efficient Extraction of Valuable Metals from Spent Lithium-Ion Batteries

A new type of deep-eutectic solvents (DESs), consisting of ethylene glycol (EG) and sulfosalicylic acid dihydrate (SAD), were designed for efficient leaching valuable metals from cathode active materials (LiCoO2 and Li14.8Ni1.7Co8.5MnO30.5) of spent lithium-ion batteries (LIBs) for the first time. The as-prepared DESs possessed strong coordination ability and low viscosity, which were suitable for metal extraction. The influences of experiment parameters on extraction of Co and Li were systematically investigated, and the leaching mechanism and kinetics were elucidated in detail. Under the optimal conditions, the leaching efficiencies of Co and Li from pure LiCoO2 reached 93.5% and 98.3%, while those of Co, Ni, Mn, and Li achieved 94.8%, 99.1%, 100%, and 100% from the spent Li14.8Ni1.7Co8.5MnO30.5, respectively. Results revealed that the Li+ ions located in the interlayer of layered LiCoO2 were replaced by H+ ions and entered into solution, while Co3+ ions in the skeleton structure were reduced and coordinated by EG and sulfosalicylic acid (SA) to form four soluble Co2+–SA complexes, realizing synergistic and efficient leaching of Li and Co from the LIB cathode active material. Moreover, Co and Li leaching kinetics conformed to the shrinking core model, in which the interfacial chemical reaction was the limiting step, and the apparent activation energies were separately about 77.38 and 79.54 kJ/mol.

The effect of Fe3+ ions on the electrochemical behaviour of ocean manganese nodule reduction leaching in sulphuric acid solution.

The effect of Fe3+ ions on the ocean manganese nodule reductive leaching in imitated sulphuric acid solutions was investigated. This work is presented in two courses, including the influence of Fe3+ ions on valuable metal extraction and the electrochemical reductive dissolution of manganese nodules. The results show that the beneficial effects of Fe3+ ion can be interpreted based on two aspects: the first is the acceleration caused by the active transformation of Fe3+/Fe2+ pair, and the second is the hydrogen ion buffer action generated by Fe3+ ion hydrolysis on the surface. On one side, Fe3+ ion could lessen the hydrogen consumption happening at the interface layer of the nodule supported by the leaching test and cyclic voltammetry results. On the other side, Fe3+ ions could be converted into Fe2+ ions and then preferentially reduce manganese oxide leading to an acceleration of the charge transfer reaction of the manganese nodule based on cyclic voltammetry, polarization, and impedance analysis results. The reduction leaching of manganese nodules in sulphuric acid solution is mainly controlled by the electrochemical interface reduction corresponding to manganese oxide dissolution, and the active conversion of the Fe3+/Fe2+ couple affects the dissolution of high valence manganese oxide.

Efficient Extraction of Valuable Metals from Spent Linixcoymn1-X-Yo2 Cathode Based on Synergistic Effects of Weakly Acidic Organic Solvents

Efficient Extraction of Valuable Metals from Spent Linixcoymn1-X-Yo2 Cathode Based on Synergistic Effects of Weakly Acidic Organic Solvents

Efficient Extraction of Valuable Metals from Spent Lithium-Ion Batteries by a Natural Deep Eutectic Solvent with Synergistic Effects

Efficient Extraction of Valuable Metals from Spent Lithium-Ion Batteries by a Natural Deep Eutectic Solvent with Synergistic Effects

A Natural Deep Eutectic Solvent with the Synergetic Effect for Efficient Extraction of Valuable Metals from Spent Ni-Co-Mn Lithium-Ion Batteries

A Natural Deep Eutectic Solvent with the Synergetic Effect for Efficient Extraction of Valuable Metals from Spent Ni-Co-Mn Lithium-Ion Batteries