This study focuses on using a green reagent scheme of methanesulfonic acid (MSA) and citric acid (CA) to extract valuable metals from the cathodes, aiming to minimize environmental impact during the recycling process. Leaching studies on LiCoO2 identified optimal conditions as follows: 2.4 mol/L MSA, 1.6 mol/L CA, S/L ratio of 80 g/L, leaching temperature of 90°C and leaching time of 6 h. The maximum Co and Li extraction achieved was 92

Chalcopyrite leaching is still remaining as the Holy Grail in hydrometallurgy. Chalcopyrite passivation limits copper leaching in a sulfuric acid system. Methanesulfonic acid (MSA) has been proven to be an alternative lixiviant to leach chalcopyrite. Therefore, solvent extraction tests were performed to confirm the compatibility of MSA. LIX-984N-C was used as an extractant to extract 2 g/L copper from copper-MSA solution at 25℃. Copper extraction enhanced to 97

CopperCopper is one of the latest additions to the list of critical minerals designated by US Department of Energy due to increasing demandDemand for electrificationElectrification and cloud storage. The expected copper demandCopper demand in 2050 will be more than 60 million tons while the currentCurrent mineMine production was only 22 million tons in 2023. Due to the consistent delays in permitting new world class mines and processingProcessing plants, it would be extremely difficult to triple the mineMine production in less than 30 years. Low gradeLow Grade materials for heapHeap or dump leachingLeaching play key roles to meet the metalMetal demandDemand. These primary sulfidesPrimary sulfides can only be processed by the process with low capital and operating costsOperating Cost. New chemical systems or processingProcessing methods have been investigated varying from chemical and biological processes. The authors have studied systems using conventional sulfuric acidsSulfuric acid, methane sulfonic acids, and glycine with various oxidants and additivesAdditives such as activated carbonCarbon. It’s been observed that in a well-controlled temperature regime and solution chemistry, copper extractionCopper extraction was not hindered by the well-known passivationPassivation. It is believed that proper control and maintenance of the solution Eh played a key role in avoiding the surface passivationPassivation. From chalcopyriteChalcopyrite concentrateConcentrate, 99

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To reduce the environmental footprint of hydrometallurgical processing of black mass from spent lithium-ion batteries (LIBs), a green leaching system based on glycine and sodium metabisulfite (Gly-SMS) was proposed. The novel leaching system was validated using black mass from end-of-life batteries and manufacturing scrap from battery producers, representing the two dominant black mass types processed in the market. The leaching study demonstrated that the highest cobalt and lithium recoveries of 100

There are over 8500 mine tailing storage facilities with the gross weight of 282.5 billion tons. These are waste dumps with less value and have been ignored for a while. The operating and maintenance costs of those facilities are not small, and they can be huge liability issues when a failure happens. It can be an environmental disaster and a huge negative impact to the company’s operations and social responsibility. However, it could be an opportunity to extract more metals. A few copper mine tailings have been tested using conventional mineral processing followed by bioleaching/biooxidation of sulfide concentrates. Metals associated with sulfides were upgraded up to 13 times, and the concentrates were microbially oxidized to extract from sulfide matrix. A mixture of mesophilic microorganisms was used for bioleaching. The extraction efficiency of metals was up to 93

Damage due to the internal degradation of electrode materials in lithium-ion batteries (LIBs) during charge-discharge cycles can cause capacity fading and safety issues. Therefore, it is essential to assess damage to LIBs using nondestructive methods. In this study, the relationship between the damage mechanism and acoustic emission (AE) activity of a commercial lithium manganese oxide (LMO)/Al-Lix alloy battery is systematically investigated. Microstructural observations of the electrodes revealed that the damage mechanisms of the LMO cathode and Al-Lix anode during accelerated charge-discharge were identical to those of microcracking. Energy, amplitude, duration, rise time, and peak frequency were considered as possible AE parameters for real-time damage detection. The generation of AE hits was prominent during the later stages of the charging and discharging processes. The AE signals produced by damage to the Al-Lix alloy anode during charging had a lower amplitude (0-60 dB) and energy (0-10 aJ). In comparison, those produced by damage to the LMO cathode during charging had a relatively high amplitude (100 dB) and energy (120 aJ). Additionally, the energy levels and amplitudes of the AE signals obtained during discharging decreased with an increasing number of cycles, indicating that they can be used as indicators for evaluating the damage progression of the primary, secondary, and tertiary cracks in LMOs. The AE technique offers the possibility of monitoring and evaluating the damage to the anode and cathode of a commercial full cell separately, as well as predicting the remaining capacity of the battery by monitoring the AE hits.& COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Growing demand for valuable battery materials and environmental issues from battery disposal make the recycling of spent lithium-ion batteries (LIBs) essential. Specifically, the green approaches using organic reagents have garnered many attentions for battery recycling. In this study, a synergetic organic leaching system using methanesulfonic acid (MSA) of strong organic acid and citric acid (CA) with good chelating ability was investigated to extract valuable metals from LiCoO2. Hydrogen peroxide was used as a reducing agent to enhance leaching kinetics. Cobalt extraction of 98

Compared to other structural alloys, magnesium alloys have a relatively poor corrosion resistance and low mechanical strength, which can be further deteriorated when these alloys are subjected to joining processes using the existing joining methods. Herein, we propose for the first time an additive friction stir-welding (AFSW) using fine Al powder as an additive to improve the mechanical strength as well as corrosion resistance of AZ31B weld joints. AFSW is a solid-state welding method of forming a high-Al AZ31B joint via an in-situ reaction between pure Al powders filled in a machined groove and the AZ31B matrix. To optimize the process parameters, AFSW was performed under different rotational and transverse speeds, and number of passes, using tools with a square or screw pin. In particular, to fabricate a weld zone, where the Al was homogenously dispersed, the effects of the groove shape were investigated using three types of grooves: surface one-line groove, surface-symmetric grooves, and inserted symmetric grooves. The homogenous and defect-less AFS-welded AZ31B joint was successfully fabricated with the following optimal parameters: 1400 rpm, 25 mm/min, four passes, inserted symmetric grooves, and the tool with a square pin. The AFSW fully dissolved the additive Al into α-Mg and in-situ precipitated Mg17Al12 particles, which was confirmed via scanning electron microscopy, transmission electron microscope, and X-ray diffraction analyses. The microhardness, joint efficiency, and elongation at the fracture point of the AFS-welded AZ31B joint were 80 HV, 101%, and 8.9%, respectively. These values are higher than those obtained for the FS-welded AZ31 joint in previous studies. The corrosion resistance of the AFS-welded AZ31B joint, evaluated via hydrogen evolution measurements and potentiodynamic polarization tests, was enhanced to 55% relative to the FS-welded AZ31B joint.

The Sand Farming is one of novel biooxidation processes suitable for sulphide oxidation of low-grade refractory gold ores. It has been previously proven to be feasible and more efficient compared to other conventional sulphide oxidation processes. In this study, the Sand Farming was compared with conventional tank biooxidation to investigate biooxidation behaviors on ores with different mineralogy and compare the ultimate gold recovery. Ore samples were tested for Sand Farming biooxidation. Conventional tank biooxidation was also compared as the baseline. After each biooxidation was completed, cyanidation was conducted for gold extraction. The Sand Farming achieved the gold recovery of 75% from high grade with higher sulphur content sample (Sample A) and 68% from low grade with lower sulphur content sample (Sample B), slightly lower than tank biooxidation of 83% and 85%, respectively. Sand Farming can be an alternative to several sulphide oxidation processes with better overall economics.

Arsenic, one of the most toxic elements, is a byproduct generated from metallurgical processes of arsenic-containing ores. Arsenic can be formed into an arsenic trioxide as a byproduct during the decopperization in electro-refining process when processing high arsenic-bearing copper minerals. However, arsenic trioxide has a very high arsenic mobility, so it requires to be re-dissolved and immobilized into scorodite (FeAsO(4)2H(2)O). In this study, methanesulfonic acid (MSA) was tested for both arsenic trioxide leaching and scorodite precipitation. Arsenic trioxide leaching tests showed the arsenic extraction of 80% at 21 degrees C in MSA with H2O2 as an oxidant within 6 hours. Meanwhile, arsenic precipitation tests were conducted to achieve above 95% arsenic removal within 6 hours by the formation of scorodite at an initial pH of 0.5 and temperature of 80 degrees C. In addition, coarser scorodite particles were formed in higher temperature and lower solution pH. The optimum condition for scorodite crystallization in MSA medium can be suggested to be at 80 degrees C with the initial pH of 0.5.

Gold extraction from porphyry copper-gold ore is challenging due to the presence of copper and sulfide minerals. In this study, pressure oxidation (POX) was used for copper extraction and gold liberation from the sulfide mineral matrix. The POX residue was investigated for gold mineralization and leaching study. Gold deportment study was conducted using a series of techniques, including X-ray diffraction (XRD), optical microscope, scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX), and dynamic secondary ion mass spectrometry (D-SIMS). Cyanidation was compared as a baseline for gold extraction; ammoniacal thiosulfate ((NH4)2S2O3) and non-ammoniacal thiosulfate (Na2S2O3) were investigated as alternative leaching conditions. In this work, POX achieved a high copper removal percentage and left 0.66% copper in the residue. Undestroyed sulfide minerals such as chalcopyrite, pyrite, and molybdenite presented with 2.7%. Hematite formed during POX and accounted for 66% of the total mineral phases. Meanwhile, hematite was the major submicroscopic gold carrier, containing 64.7% of the total gold as colloidal gold. Visible gold was identified as 24.4%. Gold extraction tests revealed that the maximum gold extraction achieved by cyanidation was 85% using 250 mg/L NaCN, consistent with the gold deportment study. Similar gold recovery was observed using 0.03 M (NH4)2S2O3, but it reduced drastically in Na2S2O3 leaching solution due to the absence of ammonia.

Methanesulfonic acid was proven to be an alternative lixiviant for copper leaching from chalcopyrite with hydrogen peroxide as an oxidant. Two alternative oxidants, dichromate and nitrate, were studied for the copper dissolution from chalcopyrite, a refractory copper sulfide mineral. During chalcopyrite leaching tests, both oxidants achieved the copper extraction above 90% in 30 g/L methanesulfonic acid at 75oC. The activation energies in dichromate and nitrate leaching systems were 23 and 43 kJ/mol, classified as mass transfer and chemical reaction-controlled mechanism, respectively. The XRD analysis of a leached residue showed a formation of K-Cr-jarosite from methanesulfonic acid-dichromate system. Methanesulfonic acid with nitrate leaching system could be the most effective and sustainable for chalcopyrite leaching based on the comparative investigation.

Since flexible devices are being used in various states of charge (SoCs), it is important to investigate SoCs that are durable against external mechanical deformations. In this study, the effects of a mechanical fatigue test under various initial SoCs of batteries were investigated. More specifically, ultrathin pouch-type Li-ion polymer batteries with different initial SoCs were subjected to repeated torsional stress and then galvanostatically cycled 200 times. The cycle performance of the cells after the mechanical test was compared to investigate the effect of the initial SoCs. Electrochemical impedance spectroscopy was employed to analyze the interfacial resistance changes of the anode and cathode in the cycled cells. When the initial SoC was at 70% before mechanical deformation, both electrodes well maintained their initial state during the mechanical fatigue test and the cell capacity was well retained during the cycling test. This indicates that the cells could well endure mechanical fatigue stress when both electrodes had moderate lithiation states. With initial SoCs at 0% and 100%, the batteries subjected to the mechanical test exhibited relatively drastic capacity fading. This indicates that the cells are vulnerable to mechanical fatigue stress when both electrodes have high lithiation states. Furthermore, it is noted that the stress accumulated inside the batteries caused by mechanical fatigue can act as an accelerated degradation factor during cycling.

Pressure oxidation (POX) is an effective method for base metal extraction and a pretreatment of refractory gold ores. A residue from pressure leaching of chalcopyrite concentrate was collected and investigated for gold recovery and deportment of metals. A comprehensive mineralogical analysis and gold deportment study were conducted using techniques including X-ray diffraction (XRD), optical microscope, scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX), and dynamic secondary ion mass spectrometry (D-SIMS). Gold leaching tests were performed using cyanide and glycine as lixiviants. The gold grade is 3.1 g/t, with 0.31% residual copper in the sample. Hematite was a dominant iron oxide (31.5%), and iron sulfate salts (45.4%) existed in various minerals phases. The gold deportment study revealed that 32.3% of the total gold was present as a visible gold, and the remainder was sub-microscopic gold. The visible gold was native gold with an average particle size of less than 20 mu m. Colloidal gold, the dominant existence of invisible gold, was found in hematite, jarosite, and iron sulfate. Hematite was the major sub-microscopic gold carrier, forming a nonporous rimmed structure and locking gangue minerals randomly. Gold in arsenopyrite was found as solid-solution, accounting for 7.2%. Gold extraction of 84% was achieved by 500 mg/L NaCN, while only 35% of gold was extracted by 100 mg/L NaCN. A significant synergistic effect of cyanide and glycine was observed. The addition of glycine in cyanide leaching solution boosted the gold leaching kinetics and recovery. Gold recovery of 85% was observed with 100 mg/L NaCN and 0.3 M glycine in 24 h. In the hybrid leaching system, copper was stabilized by glycine and further utilized as a catalyst for gold leaching. To achieve higher gold extraction and lower lime consumption, a product with high sulfur oxidation degree and low iron sulfate content is preferable in pressure oxidation operation. Hematite is a stable product and does not impair gold leaching.

An investigation on copper leaching from a chalcopyrite concentrate in methanesulfonic acid (MSA) and hydrogen peroxide at 75 degrees C was carried out. Periodic additions of H(2)O(2)were applied to enhance chalcopyrite dissolution and the reaction mechanism was analyzed using a shrinking core model. The results revealed that compared with the addition of H(2)O(2)at the very beginning, periodic additions of H(2)O(2)enhanced copper extraction and leaching kinetics, and the rate-determining step shifted from the diffusion of oxidant to the surface chemical reaction. The reaction orders with respect to MSA and H(2)O(2)were found to be 0.19 and 1.26, respectively, suggesting the leaching process was highly dependent on H(2)O(2)concentration. Calculated activation energy between the temperature range of 25-75 degrees C was 79.8 kJ/mol. Detailed study also indicated the reaction mechanism is diffusion-controlled through a protective sulfur layer at lower temperature and surface chemical reaction-controlled at temperatures higher than 55 degrees C. Overall, the MSA-H(2)O(2)leaching system is a green method for chalcopyrite leaching and a possible flowsheet in the industrial application with the periodic additions of H2O2.

Bipolar electrodialysis was used in a process of desalting a lithium sulfate solution, converting it to lithium hydroxide and sulfuric acid, and concentrating and recovering them. The effects of the experimental variables such as applied voltage, the concentration of electrode solution, the concentration of raw material solution, volume ratio, and impurity were confirmed. The optimum conditions were investigated by comparing the conversion(%) of lithium hydroxide and sulfuric acid, the process time, and energy consumption. As the applied voltage was increased, the energy consumption tended to increase, but the processing time decreased significantly. As the concentration of lithium sulfate in the raw material solution increased, the conversion(%) of lithium hydroxide decreased. As the concentration of lithium sulfate increased, the energy consumption did not increase linearly, and energy consumption increased significantly. When a raw material solution of 0.5 M Li2SO4 or more is used in the bipolar electrodialysis process, an applied voltage of 25 V is preferable. As the applied voltage increased at a constant process time, the conversion(%) of LiOH and H2SO4 increased. Regarding the effect of the electrode solution concentration, when a 5.0 wt% electrode solution was used rather than a 3.0 wt% electrode solution, energy consumption decreased by more than 10%. When the volume of the raw material solution was increased, the processing time required for desalting increased. By using a low concentration raw material solution, it was confirmed that it was simultaneously possible to recover and concentrate lithium hydroxide and sulfuric acid through volume ratio control. When the raw material solution contained Na as an impurity, it was converted to NaOH with a surface LiOH, and it was not possible to separate the lithium and sodium.

Microbial community and metabolic potential changes in a biological wastewater treatment reactor were investigated using phylogenetic and functional profile analysis from 16S rRNA-gene-based pyrosequencing. Stirred-tank bioreactors fed by cyanide-containing synthetic solutions were inoculated with a sewage sludge and the cyanide-degrading microbial consortium. A better cyanide degradation was observed in the reactors containing the phylum Proteobacteria, but lower efficiency was observed when Firmicutes and Bacteroidetes were dominant. This study shows the important role of phylum Proteobacteria for the cyanide-containing wastewater treatment in the gold processing plant and contributes the fundamentals about the microbial community exposed to the cyanide.

In order to manufacture lithium carbonate to be used as a raw material for a secondary lithium battery, lithium sulfate solution is used as a precursor, and the concentration of lithium is required to be 10 g/L or more. Electrodialysis (ED) was used as a method of concentrating lithium in a low-concentration lithium sulfate solution, and multistage concentration (MSC) electrodialysis was used to increase the concentration ratio (%). When MSC was performed using a raw material solution containing a large amount of sodium sulfate, the process lead time was increased by 60 min. And the concentration ratio (%) of lithium decreased as the number of concentration stages increased. In order to remove sodium sulfate, methanol was added to the raw material solution to precipitate sodium sulfate, and when it was added in a volume ratio of 0.4, lithium was not lost. Using a solution in which sodium sulfate was partially removed, fourth-stage concentration ED was performed to obtain a lithium sulfate solution with a lithium concentration of 10 g/L.

Microbial enhanced sulfide oxidation is one of the alternatives to roasting or pressure oxidation (POX). High grade whole ores or upgraded sulfide concentrates can be processed using POX or roasting processes but the high capital and operating costs often prohibit to process lower grade materials using these process methods. Sand Farming process is a novel alternative to POX or roasting for medium to low grade materials. The key advantage of the process is to use a relatively coarser material compared to POX or roasting. The POX and roasting processes utilize fine ground materials with P80 75 mu m or smaller to achieve higher gold recovery. The Sand Farming process uses agglomerated sample of P80 0.60?mm and the comminution cost saving is significant. Ore samples were collected from a gold mine in Mexico and two metallurgical composites were prepared for the study. Comp #1 contains 2.7 g/t of gold and 15.4 g/t of silver with 0.33% copper and 0.11% arsenic. The total sulfur was 5.7% and the sulfide sulfur was 5.6%. Gold and silver grade of Comp #2 was 1.2 g/t and 8.8 g/t, respectively. Copper and arsenic concentrations were lower than 0.07% and 0.03%. Total sulfur was 5.0% with 4.9% sulfide sulfur. The gold recovery from the Sand Farming was comparable to POX and roasting. Roasting calcine yielded the gold extraction of 70% while gold extraction from POX residue showed about 90%. After 44 days of Sand Farming biooxidation, 80% and 90% gold extractions were observed from Comp #1 and Comp #2, respectively. The gold extractions were further increased to 92% and 96% after 83?days of biooxidation.