• Journal of the Korean Ceramic Society
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• v.37 no.12
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• pp.1165-1171
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• 2000

Ti-C-Ni 혼합분말을 이용하여 SHS 공정에 의해 TiC-Ni 복합체를 제조하였으며, 리칭(leaching) 공정을 통하여 Ni을 제거함으로써 TiC 분말을 얻었다. TiC 분말의 특성분석을 위하여 XRD, SEM, TEM, AES 등을 사용하였다. 리칭 공정에 의해 얻어진 TiC 분말은 구형을 유지하고 있으며, 평균 입자크기는 0.4$\mu\textrm{m}$였다. 구형 TiC 분말을 다시 Ni 분말과 혼합하여 소결한 후 특성을 분석하였다. 140$0^{\circ}C$에서 소결하였을 때 TiC 입자는 구형에서 각진 형태로 변화하였다. 기계적 특성결과 상용 TiC 분말을 사용하였을 때보다 SHS 공정에 의해 제조된 TiC 분말을 사용하여 소결하였을 경우 파괴 인성값이 약 20% 증가하였다.

• Resources Recycling
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• v.4 no.1
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• pp.46-51
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• 1995

After removal of mercury in the silver oxide batteries with the distillation process, the leaching of valuable metals from the residue was studied. The distilled residue was reacted with the various HNO, concentration, reactlon temperature, readion time and pulp density. It was found that the optimum condition for leachmg was 2N HNO,, 40-60% reaction temperature, 6 hours reaction tlme and 10g/200ml pulp density. More than 99% of silver and zinc were dissolved in this process while less than 50% of iron and nickel were leached

• Resources Recycling
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• v.23 no.2
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• pp.53-60
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• 2014

In order to separate Indium and Tin from spent indium tin oxide (ITO) sludge, direct hydrochloric acid leaching and thermal reduction followed by HCl leaching were applied. In case of direct leaching of spent ITO, leaching rate of In and Sn was 18.5% and 19.95%, respectively. Whereas, in case of thermal hydrogen treatment of ITO sludge at different temperatures such as $700^{\circ}C$, $800^{\circ}C$, $900^{\circ}C$ and $1100^{\circ}C$, followed by HCl leaching, we obtained the result of more than 97% leaching rate of Sn. Specially, thermal treatment at $800^{\circ}C$ showed the highest leaching rate of 98.2% of Sn. Precipitation method was used for separation and recovery of Sn from leached mixed solution. If the solution pH were adjusted 2.0, 99.69% of Sn precipitated and 10.3% of In was precipitated. This confirmed the possibility of separation of Sn and In from leached solution by precipitation method.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.46-52
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• 2015

A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid ($H_2SO_4$) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of $H_2SO_4$ was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol $H_2SO_4$, and the effect of temperatures was investigated under the condition of 30 to $80^{\circ}C$. As a result, praseodymium oxide ($Pr_6O_{11}$) existing in the slag was completely converted into praseodymium sulfate ($Pr_2(SO_4)_3{\cdot}8H_2O$) after the leaching of 5 h. On the basis of the shrinking core model with a shape of sphere, the first leaching reaction was determined by chemical reaction mechanism. Generally, the solubility of pure REEs decreases with the increase of leaching temperatures in sulfuric acid, but REE slag was oppositely increased with increasing temperatures. It occurs because the ash layer included in the slag is affected as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction was determined to be $9.195kJmol^{-1}$. In the second stage, the leaching rate is determined by the ash layer diffusion mechanism. The apparent activation energy of the second ash layer diffusion was determined to be $19.106kJmol^{-1}$. These relative low activation energy values were obtained by the existence of unreacted ash layer in the REE slag.

• Clean Technology
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• v.29 no.2
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• pp.87-94
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• 2023

The recovery of valuable metals from waste lithium-based secondary batteries is very important in terms of efficiently utilizing earth's limited number of resources. Currently, the cathode material of a LiFePO₄ battery, a type of battery which is widely used in automobiles, contains approximately 5% lithium. After use, the lithium in these batteries can be used again as a raw material for new batteries through lithium recycling. In this study, low-concentration sulfuric acid, a commonly used type of inorganic acid, was used to selectively leach the lithium contained in a waste LiFePO₄ cathode material powder. In addition, in order to compare and analyze the leaching efficiency and separation efficiency of each component, the optimalleaching conditions were derived by applying a two-step leaching process with pulp density being used as a variable during leaching. When leaching with pulp density as a variable, it was confirmed that at a pulp density of 200 g/L, the separation efficiency was approximately 200 times higher than at other pulp densities because the iron and phosphorus components were hardly leached at this pulp density. Accordingly, the pulp density of 200 g/L was used tooptimize the leaching conditions for the selective leaching and recovery of lithium.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.497-502
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• 1986

Soaking of soybeans is usually considered necessary as a part of further processing. However the soaking process causes the loss of soluble solids from soybean. The temperature effect on the leaching rate of soluble solids during soaking of soybeans were determined at temperatures ranging from $10^{\circ}-50^{\circ}C$. Soaking temperature and time were found to greatly influence the content of soluble solids. Solid leaching rate constant was increased with temperature ranging from 10 - 33 mg/min. Overall mass transfer coefficient of $66.7\;mg/m^2{\cdot}h$ at $20^{\circ}C$ for Saeal variety was higher as compared with other variety (Kwanggyo, Tanyob), and activation energy was found to be 4026 cal/mole. Z-values to reach different degree of leaching showed the descending tendency with increase of solid leaching.

• Resources Recycling
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• v.4 no.3
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• pp.32-39
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• 1995

Thc purpose of this study is to develop the efficient process for recovering vanadium and nickel from the incineralionash of the oil fly ash. In this paper, the physical and chemical properties of the incineration ash was examined, and theleaching characteristics of the incineration ash were investigated by water leaching and sulEuric acid leaching tcsls. The incinerationash of oil fly ash was mainly consisted of oxldes such as V,09, V,O,, NaVO,, Ni,(VO,)Z, Fe,O,, CaSO,, SiO,.Thc waler leaching showed low extraction of metallic components, while the sulfunc acid lcaching with high temperahlreand pressure increased the extraction of vanadium and nickcl considerably. For instance, the exlraction rates of the metalllccomponents on the sulfuric acid leaching were 99% for V and 45% for Ni at 90$^{\circ}$C with pH 0.5 H,SO,, and were86% for V and 75% far Ni at ZOO"C(64 psi) with pH 1.0 H-SO,. with pH 1.0 H-SO,.

• Resources Recycling
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• v.22 no.6
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• pp.55-63
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• 2013

In this study, a electrochemical-chemical combined dissolution technology was conducted by electro-generated chlorine to obtain ruthenium solution from ruthenium metal. To find out the optimum leaching conditions of ruthenium in chloride solution, this leaching process was carried out on the variation of pH, reaction time, temperature and applied voltage at the electro-generated chlorine system in the reaction bath. Also, ozone generator was used to obtain ruthenium(III) chloride solution to increase the leaching rate. The optimum condition was observed at pH 10.0, $40^{\circ}C$ within 1 hr of reaction time that more than 88% of ruthenium(III) chloride dissolved.

• 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.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.9-18
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• 2001

1. EAF Dust in Japan - Generation and Characteristics. The quantity of dust generated from EAF shops in Japan was estimated to be 520,000 tons/year in 1999. Extremely fine dust (or fume) is formed in the EAF by metal vaporization. Its characteristics such as chemical compositions, phases, particle size, leaching of heavy metal are mentioned. 2. EAF Dust Treatment Methods in Japan. In 1999, 61% of EAF dust was treated by regional zinc recovery processing routes, 25% went to landfill disposal, 4% was reused as cement material, and 10% was treated by on-site processing routes. The problems of EAF dust treatment methods in Japan are: (1) very high treatment cost, and (2) heavy environmental load (leaching of heavy metal, emission of dioxins, depletion of disposal sites, etc). It has been much hoped for that new dust management technology would be developed. 3. New technology of EAF dust treatment in Japan. In Japan, some new technologies of EAF dust treatment have been developed, and some others are in the developing stages. Following five processes are mentioned:. (1) Smelting reduction process by Kawasaki Steel, (2) DSM process by Daido Steel, (3) VHR process by Aichi Steel, (4) On-site dust direct recycling technology, and (5) Process technology of direct separation and recovery of iron and zinc metals contained in high temperature EAF off gas by the Japan Research and Development Center fur Metals.