• Resources Recycling
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• v.31 no.1
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• pp.21-28
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys of cobalt, nickel, and copper. To develop a process to separate the metallic alloys, leaching of the metallic mixtures of these three metals with H₂SO₄ solution containing 3% H₂O₂ dissolved all the cobalt and nickel, together with 9.6% of the copper. Cyanex 301 selectively extracted Cu(II) from the leaching solution, and copper ions were completely stripped with 30% aqua regia. Selective extraction of Co(II) from a Cu(II)-free raffinate was possible using the ionic liquid ALi-SCN. Three-stage cross-current stripping of the loaded ALi-SCN by a 15% NH₃ solution resulted in the complete stripping of Co(II). A process was proposed to separate the three metal ions from the sulfuric acid leaching solutions of metallic mixtures by employing solvent extraction.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.407-412
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• 1998

This study was carried out to investigate the optimum leaching conditions for the sulfation and water leaching, and separation of cerium from rare earth elements in leached solution by acid-adjusting method. The optimum conditions for the sulfation and water leaching from bastnasite concentrates are that the equivalent ration of sulfuric acid to concentrates is 2.5, calcination temperature and time are $600^{\circ}C$ and 2 hrs respectively, and the pulp density in the water leaching is 9.1%. The yield of rare earth oxide is about 93% at the above condition. The process of recovery of cerium hydroxide from leached solution by acid-adjusting method was carried out as following steps. The first step is the oxidation of the solution at pH 5 by using twice the equivalent of $H_2O_2$ solution as an oxidant. The second step is the precipitation to obtain cerium complex salt and cerium hydroxide after lowering the solution to pH 2. The last step is the oxidation-precipitation by using equivalent of $H_2O_2$ solution. From these results, it was possible to prepare cerium hydroxide with the yield of 60% and the quality of 80%.

• Resources Recycling
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• v.25 no.5
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• pp.36-43
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• 2016

The leaching behaviors of copper from chalcopyrite were investigated by sulfuric acid. The leaching of copper was examined according to concentration of sulfuric acid, leaching temperature and addition of hydrogen peroxide and ethylene glycol. The concentrations sulfuric acid and hydrogen peroxide in the leaching solution were increased, the leaching efficiencies of Cu were increased. At $30 -60^{\circ}C$, the leaching efficiency of Cu was increased but it was decreased at $70 - 80^{\circ}C$. The results were due to the increasing of hydrogen peroxide decomposition in the solution above $70^{\circ}C$. In the case of ethylene glycol added at $80^{\circ}C$, the decomposition of hydrogen peroxide was decreased and the leaching efficiency was increased. As a result of SEM analysis of leaching residue after leaching, the residue was found to porous form in the case of the ethylene glycol added and then the leaching efficiency of Cu was increased by the increase of surface area under $60^{\circ}C$ with ethylene glycol.

• Resources Recycling
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• v.29 no.6
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• pp.98-103
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• 2020

In this study, the depression behavior of zinc sulfate on the sphalerite with the addition of potassium butyl xanthate was investigated to clear the relationship between zinc sulfate and xanthate in depression of sphalerite. As a result of the experiment, it was confirmed that the depress effect of zinc sulfate on the sphalerite declined with the increase of its addition amount. From the results of SEM-EDS and FT-IR analysis, it was found out that the amorphous precipitate of metal xanthate (Zn-BX) was formed in sphalerite concentrate, when the solubility product of [Zn+]·[BX] in the pulp solution exceeded 3.71×10-11, which is the solubility of Zn-butyl xanthate. It is considered that the Zn-butyl xanthate had a negative effect on the depression of sphalerite.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.309-314
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• 1984

The species and equilibria of uranium and vanadium have been investigated in the various concentration of perchloric, hydrochloric and sulfuric acid by anion exchange chromatography. In the concentration range of $0.01\;{\sim}\;0.5M$ hydrochloric and $0.01\;{\sim}\;0.5M$ perchloric acid, uranium seems to be $UO_2^{2+}$species and in higher concentration than 0.5M hydrochloric acid $UO_2^{2+}$seems to form the chloride complex ion as $UO_2Cl^+$, $UO_2Cl_2$, $UO_2Cl_3^-$ and $UO_2Cl_4^{2-}$ according to the increase of the hydrochloric acid concentration. In the dilute(0.01N) sulfuric acid the adsorbability of uranium on anion exchange resin is strong and then decreases with increasing the sulfuric acid concentration. From this result we conclude that $UO_26{2+}$ formed the complex ion as $UO_2(SO_4)_2^{2-}$. In the perchloric acid of $0.01\;{\sim}\;0.5N$ concentration the existing equilibrium of vanadium and its constant calculated at $20^{\circ}C$ is $1.9{\times}108$ for $H_2V_{10}O_{28}^{4-}$ + $14H^+$ = $10VO_2^+ + 8H_2O$. The elution behaviors of vanadium in the hydrochloric and sulfuric acid are smiliar to those in perchloric acid.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.364-372
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• 2011

The corrosion inhibition of imatinib mesylate (IMT) on mild steel in 0.25 M sulphuric acid has been studied using gravimetric and potentiodynamic polarization techniques at various concentrations of inhibitor, temperature and fluid velocities. The results obtained showed that, inhibition efficiency (% IE) increases with increasing concentration of the inhibitor. The adsorption process on mild steel surface follows Langmuir adsorption isotherm. The values of Gibbs free energies of adsorption obtained suggest that, the adsorption process of IMT on mild steel is chemisorption. Thermodynamic parameters were evaluated and discussed. The electron orbital density distribution of HOMO and LUMO of IMT was used to discuss the inhibition mechanism. FT-IR spectroscopy and SEM images were used to analyze the surface adsorbed film.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.126-130
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• 1998

Aluminum sulfate, $AI_{2}(SO_4)_3\cdot18H_2O$ was prepared by adding of kaolin-dissolved sulphuric acid into ethanol and its thermal decomposition behavior was discussed. As-synthesized high purity precipitate particles were platelike shapes of $2\mu\textrm{m}$ size. With increasing drop rate of leach liquor into ethanol, the crystallite sizes of the precipitate decreased. The apparent activation energies for dehydration and sulfate decomposition of the precipitate were $11.9Kcal mol^{-1}$ and $48.2kcal mol^{-1}$ respectively.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.28-36
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• 2005

A hydrometallurgical process to leach cobalt from the waste cathodic active material, $LiCoO_{2}$, and subsequently to separate it by solvent extraction was developed. The optimum leaching conditions for high recovery of colbalt and lithium were obtained: 2.0 M sulfuric acid, 5 $vol.\%$ hydrogen peroxide, $75^{\circ}C$ leaching temperature, 30 minutes leaching time and an initial pulp density of 100 g/L. The respective leaching efficiencies for Co and Li were $93\%$ and $94.5\%$. About $85\%$ Co was extracted from the sulfuric acid leach liquor containing 44.72 g/L Co and 5.43 g/L Li, using 1.5 M Cyanex272 as an extractant at the initial pH 5.0 and in organic to aqueous phase ratio of 1.6:1 under the single stage extraction conditions. The Co in the raraffinate was completely extracted by 0.5 M Na-Cyanex272 at the inital pH 5.0, and an organic to aqueous phase ratio of 1;1. The cobalt sulfate solution of higher than $99.99\%$ purity could be recovered from waste $LiCoO_{2}$, using a series of hydrometallurgical processes: sulfuric acid leaching of waste $LiCoO_{2}$- solvent extraction of Co by Na-Cyanex 271 - scrubbing of Li by sodium carbonate solution - stripping of Co by sulfuric acid solution.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.353-356
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• 2006

A set of solutions of the Navier-Stokes equation for the gas inside a spherical bubble with heat transfer through the bubble wall permits to predict correctly behavior of an ultrasonically driven bubble in aqueous solutions of sulfuric acid. Calculation results of the minimum velocity of bubble wall and the peak temperature and pressure are in excellent agreement with the observed ones. Further the calculated bubble radius-time curve displays alternating pattern of bubble motion as observed in experiment.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.380-386
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• 2010

We have investigated the growth kinetics of Al oxide film by anodization in sulfuric acid solution and the electronic properties of this film using electrochemical impedance spectroscopy. Al oxide film consisted $Al_2O_3$ was grown based on the point defect model and shown the eclctronic properties of n-type semiconductor.