• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.267-272
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• 2005

Geophysical surveys were performed in three abandoned mines: Jangpoong, Kwangyang, Imchon. The main objectives of the researches include delineating the pathways of leachate from acid mine drainage(AMD), mapping buried rock wastes and tailings, detecting drainage pipes, and investigating the gallery and membrane, if they exist, Geophysical responses were well correlated with the results from water sample data(i.e., pH, EC, heavy metal contents, $SO_4^{-2}$). Main pathways of the leachate were successfully detected in electrical resistivity sections and self-potential(SP) profiles, whereas waste rocks, drainage pipes, and membranes were effectively located by incorporating seismic refraction, electrical resistivity and GPR methods.

• Resources Recycling
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• v.26 no.2
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• pp.39-45
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• 2017

In order to exclude the effect of uneven distribution of gold in anode slime, the dissolution of gold and silver from the metal mixture was investigated in different systems, such as the mixture of hydrochloric acid and oxidizing reagents ($H_2O_2$, NaClO and $HNO_3$), thiosulfate and thiourea. In the mixture of HCl and either $HNO_3$ or $H_2O_2$, Au was completely dissolved but the leaching percentage of Ag was around 1%. In both thiosulfate and thiourea solution, gold was not dissolved at all. The presence of ferric ion in acidic thiourea solution showed a favorable effect on the leaching of silver but further study is necessary to elucidate the combined effect of ferric ion and sulfuric acid.

• Resources Recycling
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• v.26 no.5
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• pp.77-84
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• 2017

White and black dross are resulted from the recycling of aluminum. There are no established processes to recover valuable materials from black dross. Hydrometallurgical processes seem to be suitable for the treatment of aluminum dross. The salts in the black dross are recovered by dissolving with water. The residues are treated by either alkaline or acid leaching. Although the leaching rate of alumina by NaOH is lower than that by acid, its intermediates are more suitable to the production of alumina-based materials. The future direction for the treatment and recovery of valuable materials from aluminum dross is discussed.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.68-76
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• 2002

In this study, we have investigated the geochemical behavior and fate of heavy metals in acid rock drainage (ARD). The ARD was collected from the area of the former Dongrae pyrophyllite mine. The Dongrae Creek waters were strongly acidic (pH : 2.3~4.2) and contained high concentrations of $SO_4$, Al, Fe, Mn, Pb, Cu, Zn, and Cd, due to the influence of ARD generated from weathering of pyrite-rich pyrophyllite ores. However, the water quality gradually improved as the water flows downstream. In view of the change of mole fractions of dissolved Fe, Al and Mn, the generated ARD was initially both Fe- and AA-ich but progressively evolved to more Al-rich toward the confluence with the uncontaminated Suyoung River. As the AR3 (pH 2.3) mixed with the uncontaminated waters (pH 6.5), the pH increased up to 4.2, which caused precipitation of $SO_4$-rich Fe hydroxysulfate as a red-colored, massive ferricrete precipitate throughout the Dongrae Creek. Accompanying the precipitation of ferricrete, the Dongrae Creek water progressively changed to more Al-rich toward downstream sites. At the mouth of the Dongrae Creek, it (pH 3.4) mixed with the Suyoung River (pH 6.9), where pH increased to 5.7, causing precipitation of Al hydroxysulfate (white precipitates). Neutralization of the ARD-contaminated waters in the laboratory caused the successive formation of Fe precipitates at pH<3.5 and Al precipitates at higher pH (4~6). Manganese compounds were precipitated at pH>6. The removal of trace metals was dependent on the precipitation of these compounds, which acted as sorbents. The pHs for 50% sorption ($pH_{50}$) in Fe-rich and Al-rich waters were respectively 3.2 and 4.5 for Pb, 4.5 and 5.8 for Cu, 5.2 and 7.4 for Cd, and 5.8 and 7.0 for Zn. This indicates that the trace metals were sorbed preferentially with increasing pH in the general order of Pb, Cu, Cd, and Zn and that the sorption of trace metals in Al-rich water occurred at higher pH than those in Fe-rich water. The results of this study demonstrated that the partitioning of trace metals in ARD is not only a function of pH, but also depends on the chemical composition of the water.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.409-410
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• 2002

우리들이 일상적인 생활을 하는 과정에서 발생되는 생활폐기물은 그 처리문제가 심각한 사회문제로 대두되고 있다. 생활폐기물을 처리하기 위하여 매립(39%)에 의존하고 있고, 일부가 소각(5%)되고 있는 실정이다. 협소한 국토사정, 매립과정에서의 악취 등 생활환경문제, 매립후 장기간에 걸쳐 유기물이 분해하는 과정에서 발생되는 침출수로 인한 2차 환경오염문제의 발생으로 앞으로 소각처리의 확대는 필연적이라 할 수 있다. (중략)

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.286-292
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• 2007

Free amino acids and volatile compounds of fresh garlic and its liqueur were investigated to search elution profile of those components as basic data for development of garlic liqueur. The garlic was soaked in 20% alcohol solution and then sampled every week for 5 weeks. The major free amino acids were L-aspartic acid, L-glutamic acid, L-arginine, L-alanine, L-proline, L-asparagine and L-serine. Neutral amino acids such as L-threonine, L-proline, L-valine and L-leucine, and aromatic amino acids such as tyrosine and phenylalanine were eluted over 80% of those content in fresh garlic after 3 weeks of soaking, but acidic, basic and sulfur containing amino acids were below 80% even after 5 weeks. Sulfide compounds such as diallyl trisulfide, diallyl disulfide, methyl allyl disulfide, 2-vinyl-4H-1,3-dithi in, 3-vinyl-3,4-dihydro-1,2-dithiin, 3,5-diethyl-1,24-trithiolane, isobutyl isothiocyanate and diallyl sulfide were identified as major volatile compounds of fresh garlic by using GC/MS. Among volatile compounds of fresh garlic, allyl alcohol, diallyl disulfide, 3,5-diethyl-1,2,4-trithiolane, diallyl trisulfide and 3,4-dimethoxy furan were eluted to liqueur, but those compounds except 3,5-diethyl-1,2,4-trithiolane were lowered in liqueur during soaking. Furfural, 5-methylfurfural, 5-hydroxymethylfurfural, dimethyl pyrazine, furfuryl alcohol, 3-hydroxy-2-bytanone and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyr-an-4-one were generated newly and their content increased in liqueur during soaking.

• Journal of Food Hygiene and Safety
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• v.3 no.2
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• pp.53-58
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• 1988

This study was carried out to discuss a colorimetric method for the determination of nitrite in meat products issued by the Ministry of Health and Social Affaires of Korea (1985). 1) The recovery rates of nitrite of test solution extracted in the room temperature were higher than those obtained by the heating extraction. 2) In the room temperature, samples prepared with the sUce were more effective than the blendina method and the distlled water as extractina solvent for nitrite was more effective tban tbe phospbate buffer solution. 3) The extracting time showed that thirty minutes were enough to extract nitrite and the diazotizingcoupling reagents, 30% of sulfanilamide and N-l-naphthylethyienediamine were better than others. 4) The nitrite in a test soiution greatly decreased when the solution was distilled. In this case, the test solution should be used as a control. 5) Ten minutes were enough to couple nitrite.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.414-417
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• 2014

LED scraps consisting of highly crystalline GaN and their leaching behavior are comprehensively investigated for hydro-metallurgical recovery of rare metals. Highly stable GaN renders the leaching of the LED scraps extremely difficult in ordinary acidic and basic media. More favorable state can be obtained by way of high temperature solid-gas reaction of GaN-$Na_2CO_3$ powder mixture, ball-milled thoroughly at room temperature and subsequently oxidized under ambient air environment at $1000-1200^{\circ}C$ in a horizontal tube furnace, where GaN was effectively oxidized into gallium oxides. Stoichiometry analysis reveals that GaN is completely transformed into gallium oxides with Ga contents of ~73 wt%. Accordingly, the oxidized powder can be suitably leached to ~96% efficiency in a boiling 4 M HCl solution, experimentally confirming the feasibility of Ga recycling system development.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.25-34
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• 1999

This geochemical study was carried out to find out the distribution of metals and cyanide in the soils around the Keum-Jung abandoned mine. Chemical analysis showed that extractable As contents in the soils near the mine exceeded 15mg/kg, Korean standard of soil contamination for farm land. The Results suggests that As contamination is due to input of tailings in the soils. According to total decomposition of tailings, As was highly concentrated in tailings. The water in a tailings impoundment was changed to acidic and contaminated by metals and sulfate which were released through oxidation of impoundment. Acid mine drainage from the tailings impoundment distribution channels directed to the paddy soils. The proper measures are required to prevent contamination of the soil and water in the vicinity of the Keum-Jung mine.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.88-94
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• 1977

A laboratory study was made of liming on the extractability of phosphate added to the uncultivated acid soils differing in clay content. The experiments were conducted with different rates of calcium carbonate and triple superphosphate at field capacity and 50% field capacity. The concentration of extractable phosphate was greatly reduced by simultaneous addition of calcium carbonate in the loam soil. When samples of the loam soil were preincubated for ranging from 0 to 50 days in the presence of calcium carbonate prior to phosphate application, the extractable phosphate concentration increased with preincubation time, and more phosphate was extracted from the soil maintained at 50% field capacity during the incubation. However, the extractable phosphate concentration in the sandyloam soil did not change with preincubation time and was not affected by moisture status. It may be concluded that the extractability of added phosphate was influenced by not only liming time but physical properties of soil.