Extraction Of Valuable Metals Research Articles

Spent Catalyst‐Derived Mo‐MOF: Triboelectric Nanogenerators and Energy Harvesting

The spent catalysts discarded during chemical manufacturing can be a source of pollution and are classified as hazardous waste. Looking at the bright sides of the mission of waste management, such as recycling and reducing, reuse such types of the spent catalyst can be chemically treated to extract valuable salts and metals. Such a process not only reduces waste disposal issues but also promotes a circular economy ecosystem. This present study aims to extract MoO3 from the spent petroleum catalyst, Mo–Ni/Al2O3, and further processing of Mo‐metal organic framework (MOF) particles using extracted MoO3 and imidazole acting as an organic binder. The structural, morphology, and thermal properties of Mo‐MOF are evaluated. The surface roughness and positive surface potential of the Mo‐MOF are achieved. The Mo‐MOF/Kapton‐based triboelectric nanogenerators (TENG) generate a 148 V voltage, 470 nA current, and 17 nC charge. Further, TENG is utilized to charge the capacitors, and powering of the electronic devices is demonstrated. The repetition of the boxing punches and exercises can be monitored using TENGs and paves the way toward intelligent sports or healthcare.

Enhanced extraction of nickel from limonitic laterite via improved nitric acid pressure leaching process

At a time when the world is practicing energy conservation and emission reduction in order to achieve carbon neutrality, it is particularly important to enhance the extraction of valuable metals from low-grade resources. In the current process of extracting valuable metals from limonitic laterite, the characteristic that the laterite is a highly porous mineral is often overlooked. Inspired by our previous studies on the porous kinetics of limonitic laterite during nitric acid pressure leaching, this paper investigated the enhanced recovery of nickel from limonitic laterite. Response surface methodology was first used to optimize the nitric acid pressure leaching limonitic laterite process parameters to obtain the optimum conditions (Temperature: 194 °C, Time: 75 min, Liquid/Solid: 3.4 mL/g, and the initial nitric acid concentration: 178 g/L). Based on this process condition, two enhancement options were performed, namely bleed air treatment and adding surfactant. The results showed that both bleed air treatment and the addition of surfactant promoted the leaching of limonitic laterite. The best enhancement was achieved by DTAB (dodecyl trimethyl ammonium bromide), with a 5.22% increase in nickel extraction under optimal process conditions (from 90.63% to 95.85%). Furthermore, the analysis of the reinforcement mechanism shows that the bleed air treatment mainly removes the obstruction of the leaching reaction by the air in the pore, thus accelerating the reaction. The reinforcing effect of surfactants is mainly based on improved diffusion efficiency and increased permeability.

Selective separation of Al, Fe, and Ti from red mud leachate by Fe-Ti iso precipitate flotation and reduction hydrolysis process: Ions selective chelation and separation mechanism

Bauxite residue (red mud) is a typical solid waste discharged from the aluminum metallurgy industry and can be considered as an alternative resource for the recovery of iron (Fe), aluminum (Al), and titanium (Ti). Acid leaching is an effective technique for the simultaneous extraction of valuable metals from red mud, whereas the leachate with various metals confronts the difficulty of metals separation. In this work, a selective separation and recovery of Fe, Al and Ti from red mud leachate by the preferential Fe-Ti iso precipitate flotation followed by a reduction-hydrolyzation process was proposed. In the iso precipitate flotation process, the cupferron was acted as an Fe-Ti synchronous chelation agent and hexadecyl trimethyl ammonium bromide (CTAB) was used as an anionic collector for the flotation separation of Fe-Ti chelate. The generated fine hydrophobic chelates are rapidly separated from solution by flotation with the assistance of CTAB, in which 99.3% Fe and 99.8% Ti were transferred into the flotation product, while 96.7% Al remained in the leachate, realizing the first separation of Al. Reduction-hydrolyzation was further conducted to separate Ti and Fe from the dissolving solution of the flotation product. Hydrolysis thermodynamic analysis indicated that the required hydrolysis pH range of Fe2+ was much different from that of TiO2+ and Ti3+. After selective reduction of Fe3+ to Fe2+ by KI, 99.8% Ti was concentrated in the residue while 94.8% Fe remained in the solution. Eventually, the comprehensive recoveries of Fe, Ti, and Al are 94.1%, 99.7%, and 96.7%, respectively.

A Comparative Study on Bioleaching Properties of Various Sulfide Minerals Using Acidiphilium cryptum

Bioleaching has been regarded as a green alternative to chemical leaching in metal extraction processes. In this study, the bioleaching properties of indigenous acidophilic bacteria for various sulfide minerals were compared and evaluated in terms of pH reduction and metal leaching. The primary minerals in the samples were sphalerite (ZnS) (SP), galena (PbS) (GN1 and GN2), pyrite (FeS2) (PY), and chalcopyrite (CuFeS2) (CCP), and an indigenous acidophilic bacterium, Acidiphilium cryptum (99.56%), was applied for bioleaching experiments. The metal extraction in bioleaching differed according to the mineral content. The leached metal concentration of Zn was higher than that of Pb for the SP sample with a high ZnS content, whereas the concentration of Pb was higher than that of Zn for the GN1 and GN2 samples with a high PbS content. Meanwhile, the leaching rate of Zn was faster than that of Pb for all samples. Corrosion action was observed on the surface of bacterial residues in SP and GN1 samples. These results show that the bioleaching mechanism based on sulfide minerals proceeds through indirect biological oxidation, chemical oxidation, and direct bacterial oxidation. The results of this study can provide basic research data for process optimization when employing bioleaching to extract valuable metals.

Extraction of valuable metals from spent cathode materials by reductive roasting in methane atmosphere

Against the backdrop of the increasing amounts of lithium-ion batteries, it is reducing environmental pollution and relieving the stress on resource requirements through the sustainable recycling of spent lithium batteries. Here we targeted the reduction of the material phase by methane roasting and then achieved a step separation of Li, Ni, Co, and Mn by differentiation in water solubility and magnetic strength. The principal reduction factors were also optimized. The results show that the spent cathode powder converts mainly to water-soluble Li2CO3, that the leaching selectivity of lithium is 100%, and that other metals can be separated by wet magnetic separation under optimal conditions. A reasonable explanation of the phase conversion during the reduction process is provided, and a preliminary process evaluation is presented at the end. Notably, this work has the strengths of step recovery of elements, rapid processing, and zero chemical use, which has great potential for the industrial recycling field and provides a new idea for the development of green and efficient valuable metal recovery technologies for spent LIBs.

An efficient and environmental friendly strategy for alumina extraction and Fe–Si alloys production from coal fly ash by combining vacuum thermal reduction, alkali dissolving, and magnetic separation

With the strengthened awareness of environmental protection and the growing interests of wastes recycling, extraction of valuable metals from coal fly ash (CFA) has drawn extensive attention all over the world. In this paper, an environmental friendly strategy for alumina extraction and Fe–Si alloy production from CFA by combining vacuum thermal reduction, alkali dissolving, and magnetic separation was proposed. The results indicate that the stable mullite phase (Al6Si2O13) of CFA could be converted into CaO·xAl2O3 and Fe–Si alloy successfully during the vacuum thermal reduction with the assistance of CaO and Fe2O3. Additionally, the produced CaO·xAl2O3 can be dissolved subsequently by the alkali solutions to extract alumina and generate CaCO3, while the Fe–Si alloy cannot be dissolved. Finally, the CaCO3 and Fe–Si alloy in the dissolving residues can be separated effectively by magnetic separation. In this process, the alumina extraction rate attained 94.62% and there almost no waste was generated, indicating that an efficient and environmental friendly approach for valuable metals recovery from CFA was obtained.

Rapid extraction of valuable metals from spent LiNixCoyMn1-x-yO2 cathodes based on synergistic effects between organic acids

The slow rate of organic acid leaching is the main factor hindering the ecological recycling of spent lithium-ion battery (LIB) cathode materials. Here, a mixed green reagent system of ascorbic acid and acetic acid is proposed to leach valuable metal ions from the spent LIBs cathode materials rapidly. In 10 min, 94.93% Li, 95.09% Ni, 97.62% Co, and 96.98% Mn were leached, according to the optimization results. Kinetic studies and material characterization technologies like XRD, SEM, XPS, UV–vis, and FTIR show that the “diffusion” and “stratification” effects of acetic acid contribute to the dual-function leaching agent ascorbic acid quickly extract metal ions from spent LiNi0.5Co0.3Mn0.2O2 (NCM532) materials at a mild temperature. In addition, the density-functional theory (DFT) calculations of spent NCM532 structural surfaces and leaching agents show that the fast leaching of valuable metal ions is due to the synergy between ascorbic acid and acetic acid. These results provided an approachable thinking for developing advanced and environmentally friendly strategies for recycling spent LIB cathode materials.

Optimized extraction of mesoporous nanocomposites from spent Li-ion batteries and their use to construct high-performance supercapacitor devices with ultra-high stability

Lithium-ion batteries (LIBs) are one class of the most significant energy storage devices used nowadays. However, a huge number of spent batteries bring harmful resource waste and environmental hazards as LIBs are mainly composed of heavy metals and organic electrolytes. Consequently, recycling spent LIBs has become a hot topic lately, where researchers are actively working to develop a plethora of methods to extract valuable metals and components. In this study, mesoporous Li–Ni–Mn–Co oxide nanoparticles have been successfully extracted from spent Li-ion batteries using a simple microwave/precipitation method. The as-extracted Li–Ni–Mn–Co oxides were used to construct functional supercapacitor devices. However, the as-extracted oxides showed poor stability and low conductivity. To enhance their cycling stability and conductivity, fullerene (C76) is used as a carbon additive to form Li–Ni–Mn–Co oxide/C76 nanocomposite materials. The morphological, structural, and compositional analyses of those composites were performed using FESEM, HRTEM, XRD, and XPS techniques. The Li–Ni–Mn–Co oxide/C76 nanocomposites exhibit higher conductivity and wettability with an enhanced gravimetric capacitance of ∼357 Fg-1 at 1.0 Ag-1. The asymmetric supercapacitor devices deliver specific energy as high as ∼10 Wh/kg at a specific power of ∼800 W/kg with a superior retention rate of ∼115% after 20,000 cycles with ∼100% Coulombic efficiency.

Battery Technology – A Comprehensive Review

Depletion of fossil fuels, stringent pollution norms have made a way for research on the systems that can store energy from renewable sources like solar and wind. Electrical vehicles (EVs) and hybrid vehicles (HEVs) density worldwide are increasing at faster rate and have projection estimate of more than 140 million (HEVs) and EVs on the road by 2030. Design of these advanced engines are based on the availability power source namely lithium-ion (Li-ion) battery. This paper focuses on available battery technologies, components of Li-ion batteries, key features of the battery such as energy density, power density and so on and opportunities of recycling, extraction of valuable metals from the waste batteries are also included.

Optimisation of extraction of valuable metals from waste LED via response surface method

AbstractThe valuable metals were separated and extracted from waste light-emitting diodes (LEDs) by pyrolysis and leaching process. About 98.16% Ga and 99.54% Y were recycled from the LEDs after the pyrolysis by sieving process in advance. The effects of various leaching conditions on the extraction of Fe, Cu and Ag were investigated by single factor experiments and response surface method. About 90.15% Fe was selectively extracted from the waste LEDs by H2SO4 leaching without oxidant, and 99.55% Cu and 99.36% Ag were recovered from the iron leaching residue by acid leaching with the addition of HNO3. The XRD and SEM−EDS analyses confirmed that the iron and copper were effectively extracted from the waste LEDs by the developed process.

Surfactant-enhanced extraction of valuable metals from limonitic laterite: Porous kinetics and mechanism analysis

The efficient extraction of valuable metals from low-grade mineral resources is an important initiative to implement the concept of carbon neutrality and achieve energy conservation and emission reduction. Atmospheric leaching of laterite ores is widely noted for its low cost. However, low extraction and difficulties in slurry filtration have severely restricted its development. Inspired by our previous studies on the porous kinetics, two options for improving the nitric acid atmospheric leaching (NAAL) of limonitic laterite are proposed. 84.85 % of Ni extraction is achieved under the optimal process conditions (Temperature: 98 °C, Time: 3.5 h, Liquid/Solid: 4.7 mL/g, and the initial nitric acid concentration: 487 g/L). After enhanced treatment, the Ni extraction is increased by 3.16 % (bleed air), 4.55 % (SDS: sodium dodecyl sulphate), and 5.67 % (DTAB: dodecyl trimethyl ammonium bromide), respectively. In addition, DTAB not only promotes the leaching of laterite ores but also improves the filtration performance of the slurry. The filtration rate was more than three times higher than in the absence of DTAB. The presence of silicic acid is responsible for the difficult filtration of the slurry and the low extraction of valuable metals. Analysis of the intensification mechanism shows that the bleed air treatment mainly eliminates the obstruction of leaching by air in the pores, thus increasing the effective reaction area. The reinforcing effect of surfactants is mainly due to the improvement of diffusion efficiency, the reduction of adsorption, and the increase in permeability. This paper provided a feasible option for the enhanced leaching of limonitic laterite, and the reinforcement mechanism was explained clearly. It not only responds to the call for energy conservation and emission reduction by achieving efficient extraction of valuable metals from low grade laterite resources, but also avoids the treatment of laterite ores by means of high temperature and pressure.

Life cycle assessment of valuable metal extraction from copper pyrometallurgical solid waste

China generates about 20 million tons of solid waste for copper production each year, most of which comes from pyrometallurgy, leading to substantial environmental problems. Extracting valuable metal is a common way of recycling copper pyrometallurgical solid waste (CPSW). However, its environmental effects are still unclear. This paper adopts a cradle-to-gate life cycle assessment to assess the impacts of recycling three main types of CPSW (smelting slag, copper ash, and anode slime). Results show that the prominent contributor to the environmental impacts is electricity consumption. The sensitivity analysis demonstrates that reducing electricity consumption and optimizing the electricity grid mix can reduce the environmental impact. The comparative analysis was conducted to investigate the environmental advantages between CPSW recycling and primary metal production. The results indicate that the impacts of CPSW recycling are 86%, 52%, and 79% lower than that of copper concentrate production, primary copper hydrometallurgy, and primary gold production.

Built-in anionic equilibrium for atom-economic recycling of spent lithium-ion batteries

Built-in anionic equilibrium strategy is proposed to recover lithium from spent LiFePO4cathodes with high atom economy.

Green recycling of spent Li-ion batteries by deep eutectic solvents (DESs): Leaching mechanism and effect of ternary DES

Spent Li-ion batteries (LIBs) contain large amounts of hazardous metals (Co, Ni, Li, and Mn) that cause environmental pollution and health risks. In this study, one ternary (choline chloride (ChCl):Urea: ethylene glycol (EG)) and two binary (ChCl: Urea and ChCl: EG) nontoxic deep eutectic solvents (DESs) were developed as environmentally friendly, cost-effective, and safe approaches for recycling of spent LIBs. FT-IR Analysis of DESs solvents showed that the ternary DES spectrum overlaps the spectra of ChCl:Urea and ChCl: EG. Therefore, the EG structure is stable in ChCl:Urea: EG. The leaching results indicated that temperature directly affects the extraction of valuable metals in the presence of all DESs. Among the three DES types, the ternary DES exhibits optimal extraction performance (Li:97%, Co:41%, Ni:40%, and Mn:34%). In addition, kinetic modeling was used to study the reaction mechanisms. The results showed that the mixed control model by shrinking core model (diffusion control and chemical reaction control) was the best model fitted to all data (coefficient of determination (R2) > 0.90). According to the Arrhenius equation, the activation energies for all valuable metals in the presence of all DESs are between 13 and 42 KJ/mol, reflecting a mixed control reaction.

Summary of research progress on separation and extraction of valuable metals from Bayer red mud.

Bayer red mud is a strong alkaline solid waste discharged during alumina production. Due to large emissions and strong alkalinity, red mud is now mostly dammed or buried, which not only occupies huge land but also contaminates the surrounding ecosystem, causing the risk of collapse and landslide. In addition to its overall utilization in building materials, agriculture, the environment, and the chemical industry, red mud also contains valuable metals such as sodium, aluminum, iron, titanium, and scandium and is considered to be an important secondary resource. In this paper, the physicochemical properties and hazards of red mud are first introduced, and then, the overall utilization of red mud is summarized. Then, the latest research progress on the separation and extraction of valuable metals from red mud is reviewed in detail and a new comprehensive utilization method is recommended and evaluated. This paper also provides suggestions for the future development direction of the comprehensive utilization technology of red mud.

A novel nanomaterial-oriented and integrated pyrohydrometallurgy of low-grade Nickel–Copper matte

Combining great targeting and cleaner technology is a potential strategic development in the metallurgy and materials industry. This paper proposed a nanomaterial-oriented and integrated pyrohydrometallurgy of low-grade nickel–copper (Ni–Cu) matte: temperature-programed roasting, followed by water leaching and the direct preparation of Cu@Ni–Co core–shell nanoparticles from its leachate. First, a three-step temperature-programed roasting process was designed, in which the effects of the roasting temperature scheme and NaCl additive on the water leaching rates of valuable metals were systematically investigated. Under optimized conditions, the water leaching rates of Ni, Cu, and Co were 96.8, 98.9, and 99.8%, respectively, while that of Fe was nearly zero. The leachate was a chlorine-free sulfate aqueous solution. The addition of NaCl in this study was 10% (100 mg/g), which was 5–10 times less than that in previous studies. The substantial decrease in the amount of chloride added during roasting greatly reduced the high temperature corrosion of chlorine and pollutant emission. It was confirmed that a small amount of NaCl induced the chlorination–sulfation coupling reactions of low-grade Ni–Cu matte in the appropriate roasting scheme, thereby promoting the selective sulfation of sulfides and obtaining chlorine-free roasting products. In addition, the nanopowder with the Cu@Ni–Co core–shell structure was synthesized by low-temperature hydrazine hydrate reduction from the leachate. Summarily, a novel NaCl roasting water leaching low-temperature reduction successfully realized the integration of a cleaner and efficient extraction of valuable metals and preparation of high-value nanomaterials from the low-grade Ni–Cu matte. This cleaner, material-oriented, and short process design greatly expands the industrial application of traditional mineral resources and their extractive metallurgy.

Extraction of metals from nickel concentrate via FeCl3·6H2O chlorination followed by water leaching and the preparation of (Ni,Cu)Fe2O4 catalyst

The traditional high-temperature smelting process of nickel sulfide concentrate has highlighted some problems, such as large loss of valuable metals, reduced economic benefits, and unclean production. Herein, a clean process of low-temperature chlorination roasting and water leaching was proposed to co-extract Ni, Cu and Co from low-grade nickel sulfide concentrate. The important factors such as concentrate particle size, roasting temperature, roasting time and chlorination agent dosage affecting the extraction of valuable metals were systematically studied, and 93.5 % Ni, 90.3 % Cu and 88.7 % Co were extracted under the optimal conditions. The thermal analysis kinetics of the chlorination process were investigated based on the differential thermal and thermogravimetric analysis (TG- DTA) combined with Kissinger method and Flynn-Wall-Ozawa (FWO) method. The results show that the apparent activation energy (Ea) of the chlorination process of the metallic minerals is 65.8 kJ⋅mol−1 and the kinetic equation can be expressed as dαdt=1.0×107exp-65,800RT1-α1.6. The (Ni,Cu)Fe2O4 (NCF) photocatalyst was prepared from leaching solution using α-Fe2O3 as a carrier to composite with other valuable metals, the photocatalytic degradation rate of which to the MB solution could reach 99.7 % within 150 min. The NCF composites could retain its photocatalytic efficiency for at least four cycles of reaction under visible light irradiation.

A clean and efficient process for simultaneous extraction of Li, Co, Ni and Mn from spent Lithium-ion batteries by low-temperature NH4Cl roasting and water leaching

The recycling of valuable metals from spent lithium-ion batteries (LIBs) has great significance for environmental protection and resource conservation. In this paper, a low-temperature clean chlorination roasting-water leaching process was proposed to simultaneously extract Li, Ni, Co and Mn from cathode material (NCM) of spent LIBs. The temperature range of chlorination roasting was determined by thermodynamic analysis to be 250–600 °C. The effect of some factors on the conversion of valuable metals in the process of chlorination roasting and water leaching was systematically studied. The results showed that more than 98 % of Li, Co, Ni and Mn could be extracted under optimized chlorination roasting and water leaching conditions. The chlorination roasting mechanism and phase transformation evolution was determined by means of thermodynamic analysis, TG-DTA, XRD, SEM and EDS. The extraction of valuable metals was realized by the reaction of the metal oxides produced by the decomposition of NCM with NH4Cl or its evolved HCl to form water-soluble metal chlorides or chlorinated metal-ammonium complexes. The chlorination technique using NH4Cl provided an effective and clean approach for the simultaneous extraction of Li, Co, Ni and Mn from spent LIBs.

Efficient dealkalization of red mud and recovery of valuable metals by a sulfur-oxidizing bacterium.

Red mud (RM) is a highly alkaline polymetallic waste generated via the Bayer process during alumina production. It contains metals that are critical for a sustainable development of modern society. Due to a shortage of global resources of many metals, efficient large-scale processing of RM has been receiving increasing attention from both researchers and industry. This study investigated the solubilization of metals from RM, together with RM dealkalization, via sulfur (S0) oxidation catalyzed by the moderately thermophilic bacterium Sulfobacillus thermosulfidooxidans. Optimization of the bioleaching process was conducted in shake flasks and 5-L bioreactors, with varying S0:RM mass ratios and aeration rates. The ICP analysis was used to monitor the concentrations of dissolved elements from RM, and solid residues were analyzed for surface morphology, phase composition, and Na distribution using the SEM, XRD, and STXM techniques, respectively. The results show that highest metal recoveries (89% of Al, 84% of Ce, and 91% of Y) were achieved with the S0:RM mass ratio of 2:1 and aeration rate of 1 L/min. Additionally, effective dealkalization of RM was achieved under the above conditions, based on the high rates (>95%) of Na, K, and Ca dissolution. This study proves the feasibility of using bacterially catalyzed S0 oxidation to simultaneously dealkalize RM and efficiently extract valuable metals from the amassing industrial waste.

Potential for recycling of spent lithium-ion batteries in China

ABSTRACT The continual increase in new energy vehicles (NEVs) has created the urgent need to recycle lithium-ion batteries (LIBs) due to the power battery installed in them. To solve the waste problem spent LIBs has created, identifying their number and utilizing them remain crucial, both as a result of economic and environmental concerns. In the current study, the logistic growth curve was adopted to predict NEV sales beginning 2013 through to 2030 in China. It is predicted NEV sales will reach 1.56 billion by 2030. Based on these figures, spent LIBs and the proportion of valuable metals they encase were estimated using the methods-of-material-flow analysis, the Weibull distribution model, and a sampling investigation. The economic potential for recycling spent LIBs from the extraction of valuable metals was therefore estimated. Results showed that based on the continual increase in NEV sales, 5.56 billion US dollars can be generated from extracting valuable metals from spent LIBs and LIBs2U.The economic potential from the recycling of spent LIBs could significantly fast-track the development of the spent LIB recycling industry in China. This could also alleviate the issue of the environmental degradation that occurs as a result of improper spent LIBs disposal.