Leaching System Research Articles

In-situ oxidation for selective lithium extraction from spent LiFePO4 cathodes by low acid dosage

Recovery of lithium from spent lithium iron phosphate batteries is crucial to alleviating the storage of lithium. This study proposes a method for the selective recovery of lithium from spent lithium iron phosphate battery cathodes using a leaching system of H2SO4 and H2O2. Efficient and selective lithium recovery was achieved through in-situ oxidation of lithium iron phosphate driven by a low acid dosage, and the mechanism of selective lithium recovery was investigated by precipitation experiments of Fe2+ and PO43−. The shrinking core model was used for the kinetic analysis of the leaching process, and the results suggested that the leaching process was controlled by the internal diffusion of the product layer. Moreover, essential leaching parameters such as acid concentration, H2SO4 dosage, H2O2 dosage, leaching time, and leaching temperature were systematically investigated. The results showed that the leaching rate of Li reached 97.95 % along with a selectivity of 99.60 %, which meets the standard of the battery-grade Li2CO3, while the leaching rate of both Fe and P was less than 1 %.

A comparison of batch and semi-batch reactors for leaching battery cathodes (LiCoO2) under controlled addition of HCl and H2O2

Recovery of cobalt and lithium from end-of-life Li-ion battery wastes have been evaluated in batch and semi-batch leaching systems. In this preliminary study, HCl and H2O2 were used as leaching and reducing agents, respectively. The comparison of batch and semi-batch processes was carried out, obtaining an improvement from 40% to 70% in the metal mass extracted (i.e. Co and Li) for semi-batch experiments under the same experimental conditions. Effects of the initial concentration of reducing and leaching agents were evaluated for a semi-batch system in which the acid was continuously fed to maintain a constant pH value. From experimental results, it was found that the concentration of H2O2 plays an important role in the leaching process in terms of selectivity. For the experiments carried out using 0.1 M of HCl and 1 M of H2O2, the percentage of Li and Co extracted was 90% for a leaching time of 30 min. The double-controlled addition of HCl and H2O2 to the semi-batch system allows the reduction of the H2O2 concentration to 0.5 M. The optimization of reactants entails not only the decrease of their consumption but also maximize the selectivity of the reactions desired, which represents promising results for the environmental sustainability of the process. Further work will examine the fate of chloride ions in the process.

Evaluation of hydrometallurgical black mass recycling with simulation-based life cycle assessment

PurposeThe recycling of lithium-ion batteries is an emerging field faced with the challenge of recovering more than the most valuable elements from the batteries. While the literature presents many innovative approaches to the problem, an overview of the technical and environmental prospects of hydrometallurgical black mass recycling remains crucial. The goal was to analyze the impacts of a black mass process flowsheet and suggest ways to further reduce the impacts of battery recycling.MethodsThe flowsheet was drafted from the literature by combining both state-of-the-art and experimentally demonstrated unit processes by starting with the leaching system, where reductive leaching is performed using only the copper and iron impurities already present in the black mass. The process targeted copper, manganese, cobalt, nickel, and lithium recovery, and three scenarios for manganese recovery were investigated. The flowsheet was simulated using HSC Sim software, and the mass and energy balances were adapted into internally consistent life cycle inventories. The scope was “gate-to-gate” in Europe and CML methodology was used for impact assessment.Results and discussionAssuming that mechanical pre-treatment carries more environmental benefits than burdens, the results indicated that hydrometallurgical black mass recycling had a tentatively lower environmental footprint compared to virgin raw materials in all impact categories except ozone depletion, the results indicated that hydrometallurgical black mass recycling had a tentatively lower environmental footprint compared to virgin raw materials in all impact categories except ozone depletion. Sulfuric acid and neutralizing chemicals were among the most significant contributors to the impacts, and therefore further analysis was conducted based on an experimental study on low acid leaching with a low (< 0.5 M) initial sulfuric acid concentration instead of the baseline 2 M. This reduced the impacts by approximately 30–40% in all categories by decreasing downstream chemical consumption, and more significantly decreased ozone depletion. The challenges and opportunities for further process improvement were also considered.ConclusionsThe study highlights the importance of process optimization to improve the environmental sustainability of battery chemical production, but also revealed critical research gaps in the experimental literature. Rather than focusing on a single unit process, experimental black mass recycling research should aim at finding solutions that are optimal for the up- and downstream units, such as minimization of aluminum in the black mass and acid consumption.

Research on the in-situ flocculation behavior of polyferric silicate for enhancing the lithium leachability in lithium-rich clay

The expansion of global lithium demand urgently requires efficient extraction technologies for lithium-rich clay recourse. However, the encapsulation of polysilicate products in the acidic leaching system impedes the migration of lithium from the mineral to the solution, resulting in a low recovery rate of lithium. Here, this study proposes an in-situ flocculation mechanism of Fe3+ on the polysilicate to reconstruct the surface structure, enhancing the leaching efficiency of lithium. Results showed that the flocculation of Fe3+ approaches the Si-O surface and reacts with silicate to form the polyferric silicate (Fe3Si2O5(OH)4). This special configuration eliminates the wrapping and adsorption effect of polysilicate while promotes the diffusion of Li+. Increased FeCl3 concentration and higher leaching temperature are beneficial for the leaching efficiency of Li. Under optimized conditions, the Li leaching efficiency in the FeCl3 leaching system reaches up to 92.81 %. This work introduces Fe3+ to overcome the limiting effect of polysilicate during acidic leaching, and affords extraordinary recovery of lithium from clay resources.

Efficient recovery of tungsten from scheelite concentrates using a sulfur-phosphorus mixed acid leaching system

Efficient recovery of tungsten from scheelite concentrates using a sulfur-phosphorus mixed acid leaching system

Oxidative Dissolution Process of Sphalerite in Fe2(SO4)3-O3 System: Implications for Heavy Metals Removal and Recovery.

Metal sulfides in waste rocks and tailings are susceptible to serious soil and water contamination due to the generation of acid mine drainage (AMD) during stockpiling. The hydrometallurgical process is one of the most essential heavy metal remediation technologies through harmless disposal and resource utilization of the waste sulfides. However, atmospheric hydrometallurgy of sulfides still faces great challenges due to low leaching efficiency and high cost. In this work, we proposed a cooperative leaching system (Fe2(SO4)3-O3) and investigated the oxidative dissolution process of sphalerite (ZnS). Under the optimal conditions, the extracted zinc reached 97.8%. Reactive oxygen species (ROS) (·OH, 1O2 and ·O2-) were identified in the radical quenching experiments. The dissolution of sphalerite did not show passivation due to the ozone's capability to oxidize the sulfur in sphalerite to sulfate. In addition, stirring rate, O3 inlet concentration, and Fe2(SO4)3 concentration had a significant effect on the dissolution of sphalerite. Meanwhile, the apparent activation energy was 24.11 kJ/mol based on kinetic fitting, which indicated that the controlling step of the reaction was mainly a diffusion process. This work demonstrated the cooperative effect of sphalerite leaching in the O3-Fe2(SO4)3 system and provided a theoretical reference for efficient and atmospheric dissolution of sphalerite.

Selective Extraction of Critical Metals from Spent Li-Ion Battery Cathode: Cation-Anion Coordination and Anti-Solvent Crystallization.

Owing to continuing global use of lithium-ion batteries (LIBs), in particular in electric vehicles (EVs), there is a need for sustainable recycling of spent LIBs. Deep eutectic solvents (DESs) are reported as "green solvents" for low-cost and sustainable recycling. However, the lack of understanding of the coordination mechanisms between DESs and transition metals (Ni, Mn and Co) and Li makes selective separation of transition metals with similar physicochemical properties practically difficult. Here, it is found that the transition metals and Li have a different stable coordination structure with the different anions in DES during leaching. Further, based on the different solubility of these coordination structures in anti-solvent (acetone), a leaching and separation process system is designed, which enables high selective recovery of transition metals and Li from spent cathode LiNi1/3Co1/3Mn1/3O2 (NCM111), with recovery of acetone. Recovery of spent LiCoO2 (LCO) cathode is also evidenced and a significant selective recovery for Co and Li is established, together with recovery and reuse of acetone and DES. It is concluded that the tuning of cation-anion coordination structure and anti-solvent crystallization are practical for selective recovery of critical metal resources in the spent LIBs recycling.

Recovery of valuable metals from cathode materials of spent ternary lithium‐ion battery using natural product as reducing reagent

AbstractIn recent years, ternary lithium‐ion batteries (LIBs) have been vigorously promoted in the field of new energy vehicles for their excellent overall performance, and the rapid growth of battery production and sales has brought about a proliferation of spent LIBs. The recycling of cathode materials of spent ternary LIBs, which are rich in many valuable metal elements, will bring multiple environmental and economic benefits. In this paper, a systematic study of the key influencing factors in the wet leaching and recycling process was carried out. A natural product tea polyphenol was innovatively used as the reducing reagent, and a sulphuric acid–tea polyphenol leaching system was constructed for the reductive acid leaching of cathode materials of spent ternary LIBs. Under the optimum leaching conditions, the leaching efficiencies of lithium, nickel, cobalt, and manganese were 99.54%, 98.88%, 99.37%, and 98.45%, respectively. After leaching, a stepwise precipitation method was used to separate and recover the valuable metal ions from the leachate. In summary, an innovatively complete recycling process route for cathode materials of spent ternary LIBs was constructed, which provides a solid theoretical basis and technical support for the efficient and clean recycling of spent LIBs.

Bioleaching of Cd from contaminated Helianthus annuus L. stalk and the safe utilization of its byproducts by Aspergillus niger

Disposal and recycling of heavy metal-enriched biomass is the key to measure the success of phytoremediation. This study employed innovative approach to use Aspergillus niger (A. niger) for the treatment of Cd-contaminated Helianthus annuus L. (sunflower) stalk after phytoremediation. Single-factor results showed that the removal of Cd at an initial pH of 3 was superior to sucrose and inoculation amount. 67.67% of Cd was removed by A. niger leaching system after 11 days based on response surface methodology optimum conditions (sucrose: 76.266 g L−1; inoculation amount: 10%; initial pH: 3), while the concentrations of nitrogen, phosphorus and potassium (N, P and K) of sunflower stalk were unaffected. While physicochemical pretreatment effectively enhanced the bioleaching efficiency, it also resulted in significant loss of P and K elements, thereby reducing the value of biomass for recycling and utilization. Therefore, the direct A. niger leaching method without pretreatment is more advantageous for the safe treatment and recycling of Cd-contaminated sunflower stalks.

Recovery of metal ions in lithium iron phosphate powder and lithium nickel-cobalt-manganate powder by electrochemical oxidation

In recent years, lithium-ion batteries have been increasingly used in electric and hybrid vehicles. It is anticipated that the first lithium-ion batteries will be discarded at the height of their useful lives in 2025, so developing an effective and ecologically friendly recycling process is essential. In this study, an electrochemical cathode synergism is proposed for the electro-catalyzed oxidation of lithium nickel cobalt manganese oxide powder and lithium iron phosphate powder to extract metal. The oxidation of Fe2+ and the release of Li+ (98 %) in LiFePO4 and the leaching of Ni (92 %), Co (91 %), Mn (94 %) and Li (97 %) from its NCM523 were mainly triggered by the rapid attack of a large amount of OH during advanced oxidation. The leaching kinetic analysis showed that the leaching system for electrochemical leaching of binary and ternary cathode materials was a chemical reaction control model, and the leaching thermodynamic analysis showed that the dissolution of each metal ion was feasible in this leaching environment. The suggested recycling technique utilizes fewer chemicals and generates less waste when compared to previous recycling techniques. The method offers a fresh approach to environmentally friendly recycling for spent lithium-ion battery leaching and recycling.

Thiocyanate facilitating thiosulfate extraction of gold via inhibiting formation of passive layer

Thiosulfate leaching is a feasible alternative for cyanidation. However, thiosulfate is easily decomposed and forms the passive layer on the ore surface, thus hindering gold extraction. In this paper, by adding thiocyanate to reduce the undesirable effect, copper-ammonia-thiosulfate leaching system is utilized to extract gold from the calcine. This research investigated the factors affecting gold extraction and kinetics of the leaching system, and the potential reason and reaction mechanism of the thiocyanate for improving gold leaching efficiency were discussed and analyzed. Gold leaching percentage is increased from 62.99% to 88.45% by adding thiocyanate that is close to that of cyanidation. By using X-ray photoelectron spectroscopy, gold in the leachate may be in the form of gold(I) thiosulfate complex. The leaching mechanism and the reason for improving gold extraction by adding thiocyanate were investigated via characterization and the leaching thermodynamic analysis. The possible reason for improving gold leaching percentage lied in that the thiocyanate reduced the decomposition of thiosulfate, thus inhibiting the form of passivation layer. According to the leaching mechanism, thiocyanate is used as an additive in the copper-ammonia-thiosulfate leaching system, which is of great significance for facilitating gold recovery, lessening thiosulfate consumption, and reducing ammonia dosage.

Leaching Vanadium from the Spent Denitration Catalyst in the Sulfuric Acid/Oxalic Acid Combined Solvent.

Huge amounts of spent denitration catalysts are produced annually as waste from the flue gas denitration process, which will cause resource waste and environmental pollution. It is important to develop an efficient method for the recovery of metals from spent denitration catalysts. In this work, the leaching of vanadium (V) from the spent denitration catalyst by the sulfuric acid/oxalic acid combined solvent was investigated. Factors that influence the leaching rate of V have been studied. Results showed that the optimal leaching rate was 95.65% by 20 wt % sulfuric acid and 0.3 mol·L-1 oxalic acid with a liquid-to-solid ratio of 20 mL·g-1 at 140 °C for 7 h. For further study of the leaching process, the leaching mechanism of V was explored subsequently. Results indicated that sulfuric acid provided a strongly acidic environment, which was beneficial to transformation, complexation, and redox reactions of V in the mixed acid leaching system. Meanwhile, oxalic acid with excellent complexation and reducing-dissolving properties promoted the formation of stable water-soluble VO2+. The "complex effect" generated from the combined acids was greatly favored for leaching V from the spent denitration catalyst.

New insights into the mechanism of pyrite oxidation in copper(II)–ammonia–thiosulfate gold leaching system: An Electrochemical, AFM, Raman spectroscopy and XPS investigation

The nontoxicity, low cost, and environmental friendliness of the Cu2+–NH3–S2O32− gold leaching system make it a viable alternative to cyanide-based systems. However, the strong influence of certain sulphide minerals (e.g., pyrite) on the performance of the former system complicates its compositional regulation. Herein, the mechanism of electrochemical pyrite oxidation in the Cu2+–NH3–S2O32− system is probed by electrochemical techniques combined with surface analysis techniques. The results indicate that the anodic oxidation of pyrite can be assigned to active, passive, or transpassive regions, depending on the applied potential, with high potentials accelerating the reactions on the pyrite surface. Thiosulphate concentration is shown to influence the surface properties and the rate of surface reactions of pyrite. AFM images indicated that the morphological changes on the pyrite electrode surface became much rougher with increasing potential. Moreover, Raman spectroscopy and XPS provided strong evidence for the analysis of the surface species of pyrite surface oxidation. Our work will further explain and provide a mechanism for the oxidation of pyrite in the Cu2+–NH3–S2O32− system. More importantly, this study is expected to be able to provide a theoretical basis for guiding the regulation and control of gold leaching reagent in the Cu2+–NH3–S2O32− system.

Increase in energy efficiency of tunnel composting by bio leaching and biogas production

Bio waste treatment can be done by composting or by digestion. Both ways of treatment have their advantages and disadvantages. The increase in energy efficiency of tunnel composting approached by a bio leaching system and bio gas production is one part of the EnBV research project. The reduction of organic matter by bio leaching and the enrichment of carbons in the leachate water can be used for increasing the energy efficiency.

Sustainable recycling of spent ternary lithium-ion batteries via an environmentally friendly process: Selective recovery of lithium and non-hazardous upcycling of residue

As more spent ternary Co-poor lithium-ion batteries (LIBs) appear, traditional recycling processes could be challenged because of the reduced revenues caused by complex separation-purification processes. In this study, a cost-effective and environmentally friendly hydrometallurgical process assisted by the versatile oxalic acid is proposed for recycling spent ternary Co-poor LIBs. In this process, lithium is selectively leached without reductants because of the differences in oxalate solubility. Its selectivity is up to 95.0 %, which is 2.5 and 9.5 times that of formic acid and phosphoric acid/hydrogen peroxide selective leaching systems, respectively. The obtained lixivium can be reused in the leaching step to realize the enrichment of Li+, thereby reducing the discharge of wastewater and energy consumption required to recover Li+ in the form of Li2CO3. Additionally, the generated residue is non-hazardously converted into a porous functional material, whose performance in environmental treatment (i.e., emerging contaminant removal) and energy storage (i.e., supercapacitors) is superior to that of previously reported multifunctional materials. More importantly, this simplified process exhibits attractive profits (approximately $2,161/t) and is applicable to recycling multiple spent ternary Co-poor LIBs (e.g., NCM523 and NCM811). This study provides a promising route to sustainably recycle spent ternary Co-poor LIBs, probably contributing to developing spent ternary LIBs resource recycling process conformed to the goal of “carbon neutrality.”

A highly efficient process to enhance the bioleaching of spent lithium-ion batteries by bifunctional pyrite combined with elemental sulfur

Bioleaching technologies have been shown to be an environmentally friendly and economically beneficial tool for extracting metals from spent lithium-ion batteries (LIBs). However, conventional bioleaching methods have exhibited low efficiency in recovering metals from spent LIBs. Therefore, relied on the sustainability principle of using waste to treat waste, this study employed pyrite (FeS2) as an energy substance with reducing properties and investigated its effects in combination with elemental sulfur (S0) or FeSO4 on metals bioleaching from spent LIBs. Results demonstrated that the bioleaching efficiency was significantly higher in the leaching system constructed with FeS2 + S0, than in the FeS2 + FeSO4 or FeS2 system. When the pulp densities of FeS2, S0 and spent LIBs were 10 g L−1, 5 g L−1 and 10 g L−1, respectively, the leaching efficiency of Li, Ni, Co and Mn all reached 100%. Mechanistic analysis reveals that in the FeS2 + S0 system, the activity and acid-producing capabilities of iron-sulfur oxidizing bacteria were enhanced, promoting the generation of Fe (Ⅱ) and reducible sulfur compounds. Simultaneously, bio-acids were shown to disrupt the structure of the LIBs, thereby increasing the contact area between Fe (Ⅱ) and sulfur compounds containing high-valence metals. This effectively promoted the reduction of high-valence metals, thereby enhancing their leaching efficiency. Overall, the FeS2 + S0 bioleaching process constructed in this study, improved the leaching efficiency of LIBs while also effectively utilizing waste, providing technical support for the comprehensive and sustainable management of solid waste.

Recovery of Li and Fe from spent lithium iron phosphate using organic acid leaching system

The valuable metals, lithium and iron, were recovered from spent LiFePO4 cathode powder by hydro- metallurgy, and the recycled products were used as raw materials for the preparation of lithium iron phosphate. By the optimization of the leaching process parameters, the leaching efficiency of Li reached 96.56% at pyruvic acid concentration of 3.0 mol/L, volume of H2O2 of 2 mL, solid-to-liquid ratio of 0.1 g/mL, reaction temperature of 80 °C, and reaction time of 20 min. The leached residue was characterized by XRD, XPS, and FE-SEM coupled with EDS, and the results showed that the leached residue was FePO4 with an Fe/P molar ratio of 0.974.After adjusting the pH of the leaching solution to 12.0 and stirring for 2 h at 80 °C, the recovery of Li from the leaching solution was enabled by in-situ precipitation in the form of Li3PO4 with a purity of 96.5 wt.%. The reaction kinetic data of Li leaching using the pyruvic acid/H2O2 solution were fit to the Avrami model with R2>0.95. The low activation energy of the Li leaching process indicated that diffusion step limited the reaction rate during the leaching process.

Insights into the use of green leaching systems based on glycine for the selective recovery of copper

Finding strategies that promote sustainability in the recovery of metals with industrial applications is imperative to reduce costs and mitigate environmental impacts. The use of environmentally friendly reagents such as glycine is being widely investigated due to the benefits that its application entails from an industrial, economic, and environmental perspective. We sought through this study to advance in the application of glycine leaching systems for the recovery of copper from different wastes and minerals while determining the optimal conditions for its recovery. Experimental results showed that among the 3 feedstocks tested (two mining wastes and one sulfide mineral) under the established operating conditions (room temperature and different alkaline pHs), the best copper recovery was obtained with the most oxidized waste at pH 9.5, which allowed a 100% of copper recovery along with low leaching of Fe and As. Furthermore, the characterization of its final post-leaching residue showed phytostimulant properties. Unfortunately, these selected conditions did not yield favorable results for the sulfide mineral and the less oxidized wastes. In this case, further research will be necessary to achieve higher metal recoveries.

Insight into a novel circulation system combined with coordination leaching and biosorption for Cu(II) efficient recycling from electroplating sludge

A novel circulation system combined with coordination leaching and biosorption process was successfully used for the direct recycling of Cu2+ from the electroplating sludge. Cu2+ was firstly efficiently leached out from the sludge by the choosing organic acid, and then it was selectively adsorbed onto a modified sorbent from the lixivium containing other co-ions including Zn2+, Ca2+, Fe3+, Cr3+, and Mg2+ under dynamic adsorption condition. The results of static leaching experiments and DFT calculations showed that citric acid showed the best leaching performance for Cu2+ among the studied organic acids and the traditional inorganic acid (HCl). To selective recovery of Cu2+ from the lixivium, ethylenediamine tetraacetic acid dianhydride (EDTAD) modified bagasse was prepared, and it had high adsorption capacity, selectivity, and good reusability toward Cu-citric acid complex. The adsorption isotherm for Cu matched with the Langmuir model with a maximum adsorption capacity of 52.2 mg/g. XPS and EXAFS analysis illustrated that the Cu-citric acid complex was broken by EDTA on the modified bagasse, and Cu2+ enriched on the sorbent while citric acid was released into the lixivium again. In the combined leaching and sorption circulation system, Cu2+ was simultaneously absorbed on the modified bagasse fixed bed column once it was leached out. Benefitting the recycling of citric acid and the continuous adsorbing of Cu of the circulation system, the leaching efficiency could be increased from 75.0 % to 92.4 %, even in the very dilute citric acid solutions (concentration of 0.01 mol/L). The combined methods could increase Cu recovery efficiency from the sludge at a low concentration of the leaching agent, which had great potential in the practical application.

Comprehensive Research on Construction and Stability of Horizontal-Well Cavity Natural Gas Storage in Thinly Bedded Salt Rocks in China

This study aimed to overcome the difficulty of conducting the horizontal-well cavity leaching test in the field and to investigate the long-term stability of the horizontal-well salt-cavity natural gas storage. The simulation test design is combined with the similarity theory to study the cavity expansion characteristics and the influence law of cavity leaching parameters. Through the design of a rubber hose connection, an integrated closed test system for multi-stage horizontal-well cavity leaching and brine drainage was built. The test system also realises the repeatable backward movement of the injection well during the test. A similarity simulation of the test design was carried out, and the test platform was constructed to carry out multi-stage horizontal-well leaching tests with a nitrogen cushion. In the horizontal-well leaching tests with a nitrogen cushion, the influence laws of the well spacing, flow rate and liquid level position on cavity expansion were investigated. Based on the morphological characteristics of the horizontal-well cavity, a numerical model of the horizontal-well salt cavity was developed, which reflects the real cavity morphology leached in the test. The long-term stability of the horizontal-well salt-cavity natural gas storage under different internal pressures was investigated through numerical simulation.