Selective Recovery Of Valuable Metals Research Articles

A tandem approach for precipitant-free highly selective recovery of valuable metals from end-of-life lithium-ion batteries using a green deep eutectic solvent

Recently, recycling lithium-ion batteries (LIBs) waste and the efficient recovery of valuable metals has become crucial for the circular economy. Deep eutectic solvents (DESs) have shown immense potential for metal extraction from end-of-life (EoL) LIBs. However, a complicated subsequent separation process is required due to the non-selectivity of the DES components for metal. Herein, we propose a tandem precipitant-free hydrometallurgical process for the selective recovery of Li and other valuable metals (Ni, Co, Mn) from EoL LIBs using a green DES. The process parameters, viz., reaction temperature (T), time (t), pulp density (S/L), and molar ratio (MR) of ethylene glycol to tartaric acid, were optimized via the statistical optimization technique of response surface methodology. The results revealed maximum extraction efficiencies of 99.2±0.5%, 96.1±1.4%, 95.2±1.2%, and 97.8±1.5% for Li, Ni, Co, and Mn, respectively, under the optimized process conditions of T = 118 °C, t = 17 min, S/L = 42 g/L, and MR = 3:1. The kinetic study showed that interfacial reaction governed the extraction process. A plausible mechanism depicting the role of DES constituents in synergistically facilitating the extraction reaction was elucidated. Moreover, Li and other metals (Ni, Co, and Mn) were selectively separated and recovered with an overall efficiency of ∼99%. The reusability of the recovered metal products and the DES were also assessed for a closed-loop recycling process. At the outset, the proposed process paves the way for a greener alternative for recycling valuable metals from EoL LIBs rather than conventional acid-based leaching processes.

Enhanced selective separation of valuable metals from spent lithium-ion batteries by aluminum synergistic sulfation roasting strategy

Recycling of spent lithium-ion batteries has become crucial due to the current situation of resource shortage and environmental pollution. Herein, the proposed process fully utilizes cheap ammonium sulfate as sulfating agent and aluminum foil of spent lithium-ion batteries itself as reducing agent for synergistically roasting the cathode material. Thermodynamic analysis and experimental results show that, different from conventional sulfation and thermite reduction roasting, aluminum synergistic sulfation roasting converts Li in the cathode material to water-soluble Li2SO4 instead of LiMn2O4 and LiAlO2, and reduces transition metals to acid-soluble low-valent oxides instead of high-valent oxides or metal elements. The effects of roasting temperature, ammonium sulfate dosage, and roasting time on the phase transformation were studied. Under the optimal roasting parameters (T = 600 °C, n[(NH4)2SO4]:n(2Li) = 1.4, t = 1.0 h) of spent ternary cathode, the water leaching efficiency of Li is 97.2 % with less than 0.5 % of Al and transition metals being co-leached. Subsequently, more than 96 % of Al and 99 % of transition metals can be extracted through alkaline and non-reducing agent acid leaching, respectively. This work provides a potential approach and valuable technical reference for the efficient and selective recovery of valuable metals directly from the spent ternary cathode with high aluminum content.

Preferentially selective recovery of lithium from spent LiCoO2 by sulfation roasting of MnSO4

The selective recovery of valuable metals from spent lithium-ion batteries (LIBs) has engrossed significant scientific attention due to prompting environmental potential and addressing resource scarcity. Hereby, we propose an innovative and economically more environment friendly manganese sulfate roasting water leaching process to selectively recuperate lithium preferentially from spent LiCoO2 batteries. Notably, it is found that manganese sulfate roasting agents can be recirculated thoroughly without SOx emission during the sulfation roasting process. To better understand the conversion mechanism of LiCoO2, the effects of numerous parameters including, roasting time, roasting temperature, and a molar ratio of MnSO4/LiCoO2 during the recovering process were investigated. An exceptional recovery rate of 98.62% with a remarkable lithium selectivity of 99.35% by manganese sulfate leaching was achieved. This work proposes an environmentally friendly and promising strategy to extract lithium selectively from spent lithium cathodes without introducing SOx emission.

Selective Recovery of Valuable Metals (Se, Te, Cu) from the Selenium Distillation Residue by Sulfuric Acid Oxidative Leaching

Selective Recovery of Valuable Metals (Se, Te, Cu) from the Selenium Distillation Residue by Sulfuric Acid Oxidative Leaching

An environmentally benign closed-loop process for the selective recovery of valuable metals from industrial end-of-life lithium-ion batteries

An efficient environmentally benign hydrometallurgical process using ethylenediamine tetraacetic acid (EDTA) as the chelating agent has been developed for the recovery of valuable metals viz., cobalt (Co), lithium (Li), and copper (Cu) from the industrial end-of-life (EoL) lithium-ion batteries (LIBs). The experimental process parameters such as EDTA concentration, temperature, solid to liquid ratio (pulp density), pH, and reaction time were optimized to achieve high metal recoveries. The experimental results revealed maximum recoveries of 93.5 ± 3.1%, 96.4 ± 2.9%, and 97.1 ± 2.4% for Co, Li, and Cu respectively, under the optimized process conditions of EDTA concentration = 0.8 M, T = 90 °C, pulp density = 50 g/L, pH = 10, and reaction time = 4 h. A shrinking core model-based kinetic investigation revealed that interfacial chemical reaction is the rate-controlling step and the apparent activation energies corresponding to Co, Li, and Cu were evaluated to be 51.9, 41.0, and 42.3 kJ mol−1, respectively. Moreover, a plausible mechanism was elucidated, highlighting the synergistic effect and the role of Cu in augmenting the extraction reaction. The chelating agent, EDTA, was also recovered during the reaction and reused for cyclic repeat tests. Finally, the recovered metals were selectively separated in the downstream process via the precipitation reactions to depict a closed-loop recycling process. The envisaged approach will pave the way for a sustainable green alternative to the acid-based leaching processes used for metal extraction from EoL LIBs.

Reductive leaching of indium and zinc from zinc neutral leach residue with sulphuric acid and sulphur dioxide

ABSTRACT Indium and zinc extractions from zinc neutral leach residue were investigated with sulphuric acid and sulphur dioxide. Sulphur dioxide maintained a low concentration of Fe3+ in the solution and promoted the decomposition of zinc ferrite. More zinc, indium, and iron dissolve into the solution, while copper co-precipitates with arsenic and sulphur into the residue. The optimal reductive leaching conditions were determined as 120 g/L H2SO4, 200 kPa sulphur dioxide partial pressure, a liquid-to-solid ratio of 8 mL/g and a stirring speed of 500 r/min at 105°C for 4 h. Extractions of 95.24% of zinc, 98.66% of iron, 95.04% of indium and 0.036% of copper were achieved. Copper in final residue exist as sulphides and can be recovered by subsequent oxygen pressure leaching. Selective recovery of valuable metals from zinc neutral leach residue is realised.

Efficient extraction and separation of zinc and iron from electric arc furnace dust by roasting with FeSO4·7H2O followed by water leaching

Electric arc furnace dust (EAFD) formed during steelmaking in electric arc furnace is rich in iron and zinc. Due to the negative effects of zinc, directly recycling as raw materials for ironmaking does not work so that it is still mostly accumulated. In this study, a novel process was proposed, wherein EAFD was roasted with FeSO4·7H2O followed by water leaching for the effective and selective extraction and separation of zinc and iron from EAFD. The optimal roasting conditions were determined as mass ratio of FeSO4·7H2O/EAFD of 1.5, roasting temperature of 675 °C, holding time of 3 h. The transfer mechanism of elements in EAFD was analyzed. 98.79% of zinc and only 0.11% of iron were dissolved in the leaching solution, respectively, avoiding the iron-removing step before the subsequent zinc electrodeposition. Meanwhile, most of Ca, Mg and Mn ions transformed into corresponding sulfates during roasting experiments and then entered leaching solution after water leaching. Thus, the leaching residue with 91.36% mass ratio of Fe2O3 could be applied as raw material for ironmaking industry. In addition, the majority of heavy metals (Pb and Cr) were remained and immobilized in the leaching residue, meeting the requirement of leaching toxicity standard. Results from this work provide a new insight into selective recovery of valuable metals from EAFD while at the same time exploiting the solid waste of Copperas.

One-step selective recovery and cyclic utilization of valuable metals from spent lithium-ion batteries via low-temperature chlorination pyrolysis

An efficient and environmentally friendly closed loop process combing low-temperature chlorination pyrolysis with water leaching is proposed for one-step selective recovery and cyclic utilization of valuable metals from spent lithium-ion batteries (LIBs). First, the spent LiNixCoyMnzO2 (s-NCM) cathode materials are pyrolyzed with NH4Cl as a chlorination agent and the valuable metals (Ni, Co, Mn, Li) can be converted into readily soluble chloride which attribute to the release of HCl and NH3 from NH4Cl. After the s-NCM cathode materials treated via low-temperature chlorination pyrolysis at 300 °C for 30 min with NH4Cl/s-NCM mass ratio of 3:1, more than 99.9% of the valuable metals can be recovered by simple water leaching. Moreover, thermodynamic analysis show that the valuable metals can be converted to chloride while the impurity metals (Fe, Al) do not participate in the reaction at this temperature, which can achieve the one-step selective recovery of valuable metals. Therefore, the water leaching solution can be directly used to synthesize regenerated pristine NCM (r-NCM) cathode materials which exhibit excellent cycle and rate performance. In summary, one-step selective leaching and regeneration of valuable metals can be accomplished by low-temperature chlorination pyrolysis. The whole process reduces the energy consumption and the environmental pollution caused by alleviating the introduction of acidic or alkaline chemicals and realize the high-value utilization of waste resources.

Synergic Mechanisms on Carbon and Sulfur during the Selective Recovery of Valuable Metals from Spent Lithium-Ion Batteries

Recycling of spent lithium-ion batteries (LIBs) has attracted ever-growing attention owing to the scarcity of critical metals and potential environmental risk. Sulfation roasting, as traditional technology, is considered uneconomical and not environmentally friendly due to tremendous consumption of energy and emission of waste gases such as SO₂ or SO₃. Hereby, a novel and cleaner sulfation roasting—a water leaching process is proposed to recover valuable metals from spent LiCoO₂ (LCO) batteries. It is found that sulfur can be recirculated thoroughly in the form of SO₄²– without the emission of SOₓ during the sulfation roasting process. Besides, the addition of graphite can promote the conversion of LiCoO₂ under relatively milder conditions than those of traditional sulfation roasting. To further understand the conversion mechanism of LCO, the effects of various parameters including roasting temperature, roasting time, the mass ratio of carbon, and the molar ratio of H₂SO₄ during the recovery of Li and Co were investigated. Approximately, 92% of the global Li can be recovered as Li₂CO₃ with a purity as high as 99.76%, and almost 100% of Co can be recovered in the form of CoSO₄ by sulfuric acid leaching. This work proposes a practicable and promising strategy for recycling valuable metals from spent LCO batteries. Meanwhile, the synergic mechanisms on carbon and sulfur for enhancing the selectivity of metal extraction are revealed.

A promising selective recovery process of valuable metals from spent lithium ion batteries via reduction roasting and ammonia leaching

In this study, a promising process has been developed for selective recovery of valuable metals from spent lithium ion batteries (LIBs). First, reduction roasting which used spent anode powder as reduction agent and water immersion are applied to preferentially recover lithium. Subsequently, an ammonia leaching method is adopted to eff ;ectively separate nickel and cobalt from water immersion residue. Results indicate that Li2CO3, (NiO)m·(MnO)n, Ni, Co are the ultimate reduction products at 650 °C for 1 h with 5% anode powder. 82.2 % Li is preferentially leached via water immersion after reduction roasting and Li2CO3 products are obtained by evaporation crystallization. Thermodynamics shows that reducing ammonia leaching is feasible for water immersion residue. Amounts of 97.7 % Ni and 99.1 % Co can be selectively leached by NH3·H2O and (NH4)2SO3 while Mn remain in the residue as (NH4)2Mn(SO3)2·H2O, (NH4)2Mn(SO4)2·6H2O and (NH4)2Mn2(SO3)3 under the optimized conditions. Ammonia leaching kinetic show the activation energy of Ni and Co is 84.44 kJ/mol and 91.73 kJ/mol, which indicate the controlling steps are the chemical reaction. Summarily, the whole process achieves the maximum degree of selective recovery and reduces the environmental pollution caused by the multistep purification.

Phenoxy Dicarboxylate-Type Functionalized Ionic Liquids for Selective Recovery of Valuable Metals

Eight functionalized ionic liquids (ILs) prepared by trihexyl(tetradecyl)phosphonium chloride ([P6,6,6,14]Cl) and phenoxy dicarboxylic acids were studied for valuable metal recovery in this paper. ...

Selective recovery of valuable metals from industrial waste lithium-ion batteries using citric acid under reductive conditions: Leaching optimization and kinetic analysis

Recycling of valuable metals from waste lithium-ion batteries (LIBs) has recently attracted significant attention due to the environmental and economical concerns. In this paper, a simple and economical leaching process based on citric acid system was developed for the leaching of metals from the industrial waste LIBs without the manual separation of current collectors, i.e. copper and aluminum foils. The results showed significantly higher leaching efficiencies of metals due to the presence of copper and aluminum. About 91% Li, 90% Co, 94% Ni and 89% Mn were leached under the optimum leaching conditions of 0.5 mol/L citric acid, solid to liquid (S/L) ratio of 80 g/L at 90 °C for 80 min. Furthermore, the effects of the addition time and species of reductant on the leaching of Li, Co, Ni, and Mn were investigated, and the selectivity over Cu and Al as well. The kinetics data revealed that the leaching of Li, Co, Ni and Mn fitted best to the Avrami equation controlled by the surface chemical reaction, whilst the leaching of Cu and Al corresponded to the surface chemical-controlled reaction based on shrinking core model. The leaching feed before and after leaching were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Environmentally benign process for selective recovery of valuable metals from spent lithium-ion batteries by using conventional sulfation roasting

Recycling of spent lithium-ion batteries (LIBs) has attracted intensive attention owing to their potential environmental risk and the importance of the supply of critical metals.

Selective recovery of indium from iron-rich solutions using an Aliquat 336 iodide supported ionic liquid phase (SILP)

Selective recovery of valuable metals from secondary (waste) sources is essential for better resource efficiency. However, low-grade waste streams typically have complex and variable compositions and low concentrations of valuable metals. Therefore, development of novel technologies, able to deal with these complex and variable waste streams, is necessary. In this work, we present a process for the separation and purification of indium from iron-rich matrix solutions making use of a supported ionic liquid phase (SILP). The SILP used in this study was synthesized by impregnating AmberliteXAD–16N with the iodide form of the quaternary ammonium salt Aliquat336. The SILP was characterized by infrared spectroscopy, elemental analysis, density, specific surface area and porosity and it was tested for the selective recovery of indium. Adsorption was preceded by the addition of an excess of iodide anions to the solution, to form indium iodide species, which were extracted to the ionic liquid of the SILP. A high selectivity for indium over iron could be achieved because iron iodide species are not stable in aqueous medium. The reaction kinetics and several adsorption parameters, including anion concentration, adsorbent mass, stripping and reusability of the adsorbent were investigated, using synthetic binary iron-indium solutions containing iron in large excess in comparison with indium, as is typically the case in low-grade ores or industrial process residues. Finally, the developed indium recovery process was validated on a real leachate of goethite residue. A pure indium solution of 49 mg L–1 was obtained with an indium-over-iron mass ratio of 7.9 and a selectivity factor equal to 5400.

Selective recovery of valuable metals from crushed electronic waste

This research was carried out to recover valuable metals from the electronic waste (e-waste). E-waste samples were crushed and thermally activated under 450 °C within 1 hour. The optimal temperature of the thermal treatment, at which all organic phases are removed and metal’s forms turned into oxides was determined. Leaching of thermally activated material using EDTA at room temperature, pH 7 for 1 hour resulted in greater than 95 % extraction of lead. Non-ferrous metals were extracted at 85 °C with a leaching solution of 2 M H2SO4 which resulted in recovery of more than 98 % of copper within 3 hours.

Selective recovery of valuable metals from spent lithium-ion batteries – Process development and kinetics evaluation

Abstract Recovery of valuable metals from spent lithium-ion battery (LIB) is of both environmental and economic importance. Acidic leaching usually encounters issues of low selectivity or slow kinetics with considerable secondary waste generation during further purification. In this research, a closed-loop process with improved leaching selectivity for recycling of spent LiNixCoyMn1-x-yO2 battery using weak acidic leachant was demonstrated. To obtain optimal conditions of the leaching process, the effects of acid concentration, solid to liquid (S/L) ratio, temperature and reductant content were systematically investigated. Almost all Co, Li, Mn and Ni could be effectively recovered into the solution while Al remained in the residue as metallic form, after one-step leaching. The role of reductant during leaching was further evaluated which was found to be critical for the leaching kinetics. It is clear that the addition of reductant could alter the rate-controlling step of leaching from the ion diffusion in the residue layer to the surface chemical reactions. With high selectivity against impurities, this research proposed and verified a process to recover high purity Li2CO3 from the cathode scrap of LIBs, and more than 90% of the global recovery rate of valuable metals can be achieved.

Thermal Analysis on the Pyrolysis of Tetrabromobisphenol A and Electric Arc Furnace Dust Mixtures

The pyrolysis of Tetrabromobisphenol A (TBBPA) mixed with electric arc furnace dust (EAFD) was studied using thermogravimetric analysis (TGA) and theoretically analyzed using thermodynamic equilibrium calculations. Mixtures of both materials with varying TBBPA loads (1:1 and 1:3) were prepared and pyrolyzed in a nitrogen atmosphere under dynamic heating conditions at heating rates of 5 and 10 °C/min. The mixtures degraded through several steps, including decomposition of TBBPA yielding mainly HBr, bromination of metal oxides, followed by their evaporation in the sequence of CuBr3, ZnBr2, PbBr2, FeBr2, MnBr2, KBr, NaBr, CaBr2, and MgBr2, and finally reduction of the remaining metal oxides by the char formed from decomposition of TBBPA. Thermodynamic calculations suggest the possibility of selective bromination of zinc and lead followed by their evaporation, leaving iron in its oxide form, while the char formed may serve as a reduction agent for iron oxides into metallic iron. However, at higher TBBPA volumes, iron bromide forms, which can also be evaporated at a temperature higher than those of ZnBr2 and PbBr2. Results from this work provide practical insight into selective recovery of valuable metals from EAFD while at the same time recycling the hazardous bromine content in TBBPA.

Effect of milling on metal leaching: Induction of galvanic effect in a secondary lead smelter matte by prolonged milling

The effect of milling on the leaching of Pb (and other metals like Fe, Cu, Ni and Zn) from a secondary lead smelter matte was studied. The effects of milling time, milling environment (dry or wet milling) and leaching reagent (Fe(III)-HNO3 or citrate solution) on the leaching efficiency of metals were investigated. A 1–2mm ferromagnetic fraction of the matte, containing 54% Fe, 5.8% Pb, 24% S and minor levels of Cu (1.2%), Ni (0.2%) and Zn (0.3%), was used. Pb leaching in a Fe(III)-HNO3 solution was enhanced from 53% (no milling) to 85% after 5min of dry milling. Prolonged milling resulted in an agglomeration of particles causing a galvanic effect (between FeS and Pb), which led to electrochemical precipitation of Pb2+ cations from the solution as PbS. Because of this electrochemical precipitation, almost no Pb2+ was detected in the Fe(III)-HNO3 solution after 10min of dry milling. In order to avoid/reduce agglomeration and to obtain a finer particle size and higher leaching efficiencies, wet milling was carried out. The highest Pb leaching was obtained after 20min of wet milling (88% in the Fe(III)-HNO3 and 94% in the citrate solution). Citrate solution was more selective towards Pb leaching, with <2% Fe leaching from the matrix material compared to 20–24% in the Fe(III)-HNO3 solution. The optimised milling and leaching steps were combined to attain a process for the selective recovery of valuable metals from secondary lead smelter matte.

Process development for hydrometallurgical recovery of valuable metals from sulfide-rich residue generated in a secondary lead smelter

Two routes were investigated to selectively recover lead and minor metals (Cu, Ni, Zn) from a sulfide-rich lead smelter residue, matte. The first route comprises a two-step leaching process that combines Fe(III)-HNO3 leaching with roasting, followed by water leaching. In the first step, the efficiency of Pb leaching was 90% at the optimum condition (L/S ratio 8, 0.5mol⋅L−1 HNO3, 0.15mol⋅L−1 Fe(III), 25°C). In the second step, roasting at 600°C followed by water leaching at 50°C selectively leached Ni, Cu, and Zn while fully converting iron sulfides to oxides. One-step oxidative pressure leaching in HNO3 was investigated as an alternative to simultaneously leach Pb, Cu, Ni and Zn. At the optimal conditions (130°C, 60min, 0.3mol⋅L−1 HNO3, 0.07mol⋅L−1 Fe(III), L/S ratio 20), Pb, Cu, Zn and Ni leaching were 92, 60, 70 and 66%, respectively, while Fe leaching remained low (2%). The leachates obtained from both leaching routes were treated by ion-exchange adsorption with diethylenetriaminepentaacetic acid (DTPA) functionalized chitosan-silica hybrid materials to investigate the selective recovery of Cu, Zn and Ni. The adsorption order appeared to be in the same order as the corresponding stability constants for complexes between the respective metal ions and free DTPA: Ca(II)<Zn(II)<Pb(II)≈Ni(II)<Cu(II). This allows not only to selectively recover Cu, Zn and Ni from the leachates, but also to mutually separate them by using the functionalized resin as a stationary phase in column chromatography. To avoid adsorbent contamination, Fe(III) and Pb(II) may be removed from the leachates in a pre-treatment step. Based on these results, the investigated methods can be combined as process steps of two possible routes for the selective recovery of valuable metals from the studied secondary lead smelting residue. The two-step leaching process seems to be superior since a more concentrated solution of Cu, Ni, and Zn is produced in the 2nd leaching step with low capital cost.

Selective leaching of Pb, Cu, Ni and Zn from secondary lead smelting residues

Several HNO3-based leaching approaches were tested and optimized to selectively recover Pb and other minor metals (Cu, Ni, Zn) from secondary lead smelter residues (i.e., slag and matte). Firstly, the leaching behaviors of Pb and the matrix element Fe were studied at atmospheric pressure in the temperature range 25—70°C. These elements were present in both materials studied as sulfide and oxide phases. For the sulfur-rich matte residue, the Pb leaching increased from 63% to 69% upon increasing the HNO3 concentration from 0.2M to 0.5M. However, by adding Fe(III) as an oxidation agent, Pb leaching from the matte amounted to 90% at 25°C. At a higher temperature, Pb leaching was reduced due to PbSO4 precipitation. In this process, Cu, Zn and Ni leaching was insignificant. For the slag residue, HNO3 could not leach Pb (0.03% Pb leached), while Fe leaching was 19.8% due to a galvanic effect. However, Pb leaching of the slag was 82% in the presence of additional Fe(III). Secondly, to enhance leaching of the other base metals (Cu, Zn and Ni) from the matte, roasting followed by water leaching and (microwave assisted or autoclave) pressurized leaching in 0.5M HNO3 were applied. During roasting, the FeS phase converted to Fe2O3 above 500°C, and PbS and Pb phases were transformed into insoluble PbSO4 above 400°C. Cu, Ni and Zn leaching was drastically enhanced by a roasting step at 600°C followed by leaching with 0.5M HNO3 at 50°C, or by pressurized HNO3 leaching above 130°C, whereby Pb leaching almost ceased due to PbSO4 precipitation. During the roasting above 600°C, or microwave assisted extraction (MAE) at 160°C for 15min, FeS was completely converted to iron oxides that can be used as raw material for pig iron production. Based on the results, the methods investigated can be combined as process steps of two possible routes for the selective recovery of valuable metals and the production of a clean source of Fe oxides from the secondary lead smelting residues studied.