• Clean Technology
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• v.30 no.2
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• pp.105-112
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• 2024

Globally, the demand for electric vehicles has surged due to greenhouse gas regulations related to climate change, leading to an increase in the production of used batteries as a consequence of the battery life issue. This study aims to selectively leach and recover valuable metal lithium from the cathode material of spent LFP (LiFePO₄) batteries among lithium-ion batteries. Generally, the use of inorganic acids results in the emission of toxic gases or the generation of large quantities of wastewater, causing environmental issues. To address this, research is being conducted to leach lithium using organic acids and other leaching agents. In this study, selective leaching was performed using the organic acid methane sulfonic acid (MSA, CH₃SO₃H). Experiments were conducted to determine the optimal conditions for selectively leaching lithium by varying the MSA concentration, pulp density, and hydrogen peroxide dosage. The results of this study showed that lithium was leached at approximately 100%, while iron and phosphorus components were leached at about 1%, verifying the leaching efficiency and the leaching rates of the main components under different variables.

• Resources Recycling
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• v.27 no.1
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• pp.22-30
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• 2018

In order to industrially recycle nickel, cobalt and rare earth elements included in waste NiMH batteries, electrode powder scraps were recovered by dismantle, crushing and classification from automobile waste battery module. As a result of leaching recovered electrode powder scrap with sulfuric acid solution, 99% of nickel, cobalt and rare earth elements were leached under reaction conditions of 1.0 M sulfuric acid solution, pulp density 25 g/L and reaction temperature $90^{\circ}C$ for 4 hours. In addition, the rare earth elements were able to separate from nickel / cobalt solution as cerium, lanthanum and neodymium precipitated under pH 2.0 using 10 M NaOH.

• Resources Recycling
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• v.26 no.5
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• pp.67-76
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• 2017

In order to efficiently recycle waste industrial nickel-cadmium batteries, anodic and cathodic materials were crushed by a cut mill and classified by sieves. We used wet magnetic separation method for eliminating iron components from the crushed powders. In addition, the acid leaching test for the obtained anode and cathode powders was carried out under various conditions by means of the wet process. At the optimum leaching conditions with 2.0 M $H_2SO_4$ at $90^{\circ}C$, 15 wt $H_2O_2$ and L/S=20 for 3 hours, the leaching efficiency of nickel and cadmium was 99%, respectively.

• Resources Recycling
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• v.32 no.3
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• pp.38-44
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• 2023

Leaching tests were conducted using sulfuric acid and sodium hydroxide solutions to remove impurities from domestic graphite concentrate. As a result of the leaching experiment using sulfuric acid solution and sodium hydroxide solution, respectively, the difference of removal efficiency was insignificant when the concentration of sodium hydroxide or sulfuric acid was 2 mol/L or more. The fixed carbon content increased with increasing the temperature in the sulfuric acid solution leaching, while it remains constant above 150℃ in sodium hydroxide solution. For the repeated sequential leaching tests, the leaching conditions were 2 mol/L NaOH, 200℃, 1 hour in the sodium hydroxide solution leaching and 2 mol/L H₂SO₄, 100℃, 1 hour in the sulfuric acid solution leaching, respectively. When sulfuric acid leaching followed by sodium hydroxide solution leaching was repeated 5 times, the fixed carbon increased to 99.95% and ash content decreased to 0.048%, while the fixed carbon increased to 99.98% and ash content was reduced to 0.018 when sodium hydroxide solution leaching followed by sulfuric acid solution leaching was repeated 5 times.

• Resources Recycling
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• v.24 no.1
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• pp.3-11
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• 2015

Soluble silica generated from acid leaching process is very difficult to filter and deceases the purity of products, and thus becomes one of hot issues in hydrometallurgy. This paper reviewed the dissolution and reactivities of silicates in acid solution, and the methods for treatment of soluble silica. Removal of silica with alkaline pre-treatment, crystallization to $SiO_2$ and precipitation behaviour of silica with coagulation under acid conditions were briefly described.

• Resources Recycling
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• v.6 no.4
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• pp.31-37
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• 1997

The Mg-ferrite powders were recovered from acid leaching Mg waste by hydrothermal method. Recovering conditions ofMg-Ferrite were investigated m this system and the powders prepared were characterized, using X-ray analysis, chemicalanalysis, SEM. TEM, and VSM. In this study, pH of solution and the kind of neutralizer wcre important factors on thecharacteristics of the product. The optimum condition of recovering MgPenite was the mole ratio of Fe" : Mg"=2'1, reactiontemperature : ZOWC, reaction time.lhr, at pH=lZ, and Oi partial pressure af 2000 psi. And the powders ~ccovered have amonodispersed and spherelike shapes with the narrow sue distribulion.ow sue distribulion.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.346-349
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• 2004

국내에 자연 방치된 폐광산에 대한 문제가 대두되면서 폐광산 주변지역에 대한 산성광산폐수와 중금속 광산폐기물의 오염실태조사가 활발히 진행되고 있다. 본 연구는 폐광산의 유출수와 광산폐기물에 주변 오염지하수 내의 중금속 As, Cd, Pb, Fe, Mn, Zn, Cu에 대하여 무기 응집제의 첨가와 pH의 조절에 의한 제거효율을 .실내 배치실험을 통하여 규명하였다. 본 실험을 통하여 황산알루미늄(Al$_2$(SO$_4$)$_3$ㆍ13～14$H_2O$), 염화 제2철(FeCl$_3$ㆍ6$H_2O$), 황산 제2철(Fe$_2$(SO$_4$)$_3$ㆍ n$H_2O$)을 이용하여 오염수내 중금속을 90%이상 제거할 수 있었으며, 폐광산 침출수나 오염 지하수의 중금속 제거에 0.1 wt%의 응집제 첨가만으로 응집제를 이용한 화학적 처리 방법이 효과적으로 사용될 수 있을 것으로 판단되었다.

• Resources Recycling
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• v.22 no.3
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• pp.43-49
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• 2013

A study on the recovery of lithium and leaching behavior of NCM powder by hydrogen reduction for NCM system Li-ion battery scraps was investigated. The reductive rate was about 93% at $800^{\circ}C$ by hydrogen treatment. The lithium carbonate with 99% purity was manufactured by using $CO_2$ gas and washing method with water for NCM powder after hydrogen reduction. As a result of comparing the powders before and after the hydrogen reduction treatment for acid leaching behavior we obtained 32% enhanced leaching rate of cobalt, 45% enhanced leaching rate of nickel and the 90% leaching effect for manganese by hydrogen reduction at 2M $H_2SO_4$ concentration condition.

• Resources Recycling
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• v.22 no.2
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• pp.44-52
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• 2013

Bioleaching behavior of metal ions for recovery of cobalt and copper from cobalt concentrate was investigated by employing three Aspergillus niger strains. Various factors, such as organic acid generation with fungi type, pH of the culture and pulp density were studied. The results showed that the best fungi for organic acid(citric acid and oxalic acid) generation was A. niger KCTC 6144 using Malt Extract Broth culture at initial pH 3.5. But A. niger KCTC 6985 was more effective for the leaching of cobalt and copper from cobalt concentrate. Our results showed that 82% cobalt and 98% copper was dissolved by A. niger KCTC 6985 at 10g/L pulp density, at pH 3.5 and $24^{\circ}C$ after 15 days incubation.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.73-79
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• 1997

Removal of the Arsenic components from the closed mine tailings has been attempted by the alkali-leaching method. Two tailings collected from the Daduck and Yuchon mine which were already closed many years ago were leached with caustic soda solutions. The Arsenic components in the leach liquor resulted from the alkali treatment of tailings could be removed fairly well in the form of insoluble calcium-Arsenic compound by the precipitation with calcium chloride. As a result, the extraction of about 60~90% Arsenic from the tailings could be obtained depending on the leaching conditions and the influence of temperature and the slurry density on the extraction of Arsenic was also found to be very small at the NaOH concentration more than 0.5N. In addition, it seemed that a caustic soda solution over 0.5N NaOH could be used repeatedly for the leaching of tailings since the consumption of NaOH was not so great in a leaching of them. As far as the precipitation of Arsenic components was concerned, more than 99% of Arsenic could be precipitated within 10 minutes by the addition of 2wt% CaC12 in to the leach liquor.