• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.207-222
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• 2014

In order to recover the metallic copper powder from the mine-waste rock, heap bioleaching, Fe removal and electrowinning experiments were carried out. The results of heap leaching with the mine-waste rock sample containing 0.034% Cu showed that, the leaching rate of Cu were 61% and 62% in the bacteria leaching and sulfuric acid leaching solution, respectively. Sodium hydroxide (NaOH), hydrogen peroxide ($H_2O_2$) and calcium hydroxide ($Ca(OH)_2$) were applied to effectively remov Fe from the heap leaching solution, and then $H_2O_2$ was selected for the most effective removing Fe agent. In order to prepare the electrolytic solution, $H_2O_2$ were again treated in the heap leaching, and Fe removal rates were 99% and 60%, whereas Cu removal rates were 5% and 7% in the bacteria and sulfuric acid leaching solutions, respectively. After electrowinning was examined in these leaching solution, the recovery rates of Cu were obtained 98% in bacteria and obtained 76% in the sulfuric leaching solution. The dendritic form of metallic copper powder was recovered in both leaching solutions.

• KSBB Journal
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• v.15 no.3
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• pp.254-261
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• 2000

A bacterial leaching was conducted for pyrite with Thiobacillus ferrooxidans(ATcC 19859) and Thiobacillus KY isolated from acid mine water around Kwangyang area to characterize the surface of substrate as reaction progress at the optimum condition under 9K medium for 3- days. It was found that the surface crystallinity changes referred to hkl plane was observed for 20 days leached by T. ferrooxidans similar changes also observed for 10 days leached pyrite by Thiobacillus KY. Based on he results of SEM-EDS the atomic ratios of Fe, S and Si on the surface were changed to sulfur rich phase but exposed Si ratio decreased from 16.94% to 4.85% during 30days mainly due to reprecipitating of Fe and S as a mixed compound.

• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1747-1754
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• 2008

Acidithiobaeillus ferrooxidans ATCC 23270 is an important model organism for bioleaching and bioremediation studies owing to its diverse metabolic capabilities, whereas lix984n is a widely used extractant. Little is known about the response of cbb genes in A. ferrooxidans to lix984n shock. Thus, to elucidate the response of the $CO_2$ fixation genes in A. ferrooxidans ATCC 23270 to the addition of lix984n, the gene expression of cbb genes was examined using a real-time PCR. Although a natural increase or decrease in the expression of most cbb genes was observed after 5 min of shock with 3% (v/v) lix984n, sdhC and cbbR exhibited quick responses to the shock. Ten min of shock had a greater effect on the cbb gene expression, yet 15 min of shock had a significant effect on the Calvin cycle in A. ferrooxidans ATCC 23270, as the expression of all the cbb genes reached a very high level. Therefore, after a short lix984n shock, a solution of A. ferrooxidans can be re-used for bioleaching.

• Resources Recycling
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• v.29 no.2
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• pp.3-7
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• 2020

Recently, the gold leaching technologies draw much interest to recover gold from low grade ores. Current leaching processes mostly use cyanide as the leaching agent, due to its high leaching efficiencies and cost-effectiveness. However, use of cyanide is severely problematic, because of toxicity and thereby environmental risks, and requires strict regulations and environmental management. Especially, this issue becomes further apparent when cyanide should be applied for dump or heap leaching for low cost gold recovery along with recent trends. To resolve this issue, the alternative leaching processes using thiosulfate or halogen compounds, instead of cyanide, have been studied and developed but there have been lots of difficulties toward commercialization, and therefore further research should be conducted. The commercialization of dump or heap bioleaching technologies should be urgently required for effective direct biogenic gold recovery from low grade ores or tailings without use of cyanide.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.39-44
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• 2010

Acidithiobacillus caldus is an acidophilic, chemolithotrophic bacterium that plays an important role in bioleaching. Gene transformation into A. caldus is difficult, and only the conjugation method was reported successful, which was a relatively sophisticated method. In this research, electrotransformation of A. caldus species was achieved for the first time using A. caldus Y-3 and plasmid pJRD215. Transformants were confirmed by colony PCR specific to the str gene on pJRD215, and the recovery of the plasmid from the presumptive transformants. Optimizations were made and the transformation efficiency was increased from 0.8 to $3.6{\times}10^4$ transformants/${\mu}g$ plasmid DNA. The developed electrotransformation method was convenient in introducing foreign genes into A. caldus.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.04a
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• pp.91-93
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• 1999

충북 단양에 위치한 조일 광산에서 채취한 구리와 아연으로 오염된 광미 (광산 폐기물로서 금속 추출 후 남은 찌꺼기)를 효율적으로 처리하기 위하여 생물학적 용출기법(bioleaching)의 효율 증진에 관한 연구를 수행하였다. 기본 배지 조성(9K medium) 중 미생물의 성장 및 증식, 용출 효율에 영향을 미치는 인자인 에너지원, 인, 질소원의 농도를 변화시키며 배지 조성에 따른 중금속의 용출 효율을 관찰하였다. 그 결과 인 농도 변화는 인을 첨가하지 않았을 때, 아연과 구리의 용출 효율이 각각 98.8%와 47.5%로 나타났고, 질소원은 45mM 농도로 주입하였을 때 아연, 구리 각각 85%와 46.4%의 용출 효율을 보였다. 에너지원 변화에 서는 아연의 경우 에너지원을 첨가하지 않았을 때 93%의 용출 효율을 나타냈고, 구리의 경우는 160mM 첨가했을 때 46.4%로 가장 높은 용출 효율을 나타냈다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.04a
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• pp.94-96
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• 1999

충북 단양에 위치한 조일 광산에서 채취한 구리와 아연으로 오염된 광미(광산 폐기물로서 금속 추출 후 남은 찌꺼기)를 효율적으로 처리하기 위한 생물학적 용출기법(bioleaching) 에서 기본 배지 조성(9K medium)을 변화시켜 미생물의 표면 특성을 측정하고 미생물 표면 특성이 용출 효율에 미치는 영향을 관찰하였다. 인을 첨가하지 않았을 때 소수성 값은 62.5％, 질소원 농도가 45mM일 때의 소수성 값은 66.7%로 미생물 표면 특성이 가장 소수성인 특성을 가지고 있었으며, 구리와 아연의 용출 효율도 가장 높게 나타나는 상관 관계를 나타냈다. 또한 광미에 부착된 미생물의 양을 측정해 본 결과, 미생물 표면 특성이 소수성일수록 광미에 부착된 미생물의 양도 많다는 것을 알 수 있었다.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.411-415
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• 2009

Some microorganisms are capable of leaching Mn(II) from nonsulfidic manganese ores indirectly via nonenzymatic processes. Such reductive dissolution requires organic substrates, such as glucose, sucrose, or galactose, as a source of carbon and energy for microbial growth. This study investigated characteristics of Mn(II) leaching from manganese nodules by using heterotrophic Bacillus sp. strain MR2 provided with corn starch as a less-expensive substrate. Leaching of Mn(II) at 25.6 g Mn(II) $kg^{-1}$ nodule $day^{-1}$ was accompanied with cell growth, but part of the produced Mn(II) re-adsorbed onto residual $MnO_2$ particles after 24 h. Direct contact of cells to manganese nodule was not necessary as a separation between them with a dialysis tube produced similar amount [24.6 g Mn(II) $kg^{-1}$ nodule $day^{-1}$]. These results indicated an involvement of extracellular diffusible compound(s) during Mn(II) leaching by strain MR2. In order to optimize a leaching process we tested factors that influence the reaction, and the most efficient conditions were $25\sim35^{\circ}C$, pH 5~7, inoculum density of 1.5~2.5% (v/v), pulp density of 2~3 g/L, and particle size <75 ${\mu}m$. Although Mn(II) leaching was enhanced as particle size decrease, we suggest <212 ${\mu}m$ as a proper size range since more grinding means more energy consumption The results would help for the improvement of bioleaching of manganese nodule as a less expensive, energy-efficient, and environment-friendly technology as compared to the existing physicochemical metal recovery technologies.

• Journal of Navigation and Port Research
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• v.29 no.6 s.102
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• pp.589-593
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• 2005

A laboratory study on the adsorption of nitrate in polluted coastal water using various materials including several types of dredged sediments(ST) and yellow c1ays(YC), which are activated by heat(HT), bioleaching for heavy metal removal(BL) and neutralization(NR) was performed. The equilibrium time of the adsorption for the sediment bioleached and treated by heat(BL-HT-ST) was only 17min which was faster than the sediment bioleached, neutralized and treated by heat(BL-NR-HT-S) (25min) or the sediment treated by the bioleaching process(BL -ST)(27min), but longer equilibrium times for yellow c1ay(YC) or heat treated yellow day(HT- YC) were required. The adsorption processes of nitrate in sea water for tested material could be described by Freundlich isotherm, but were significantly affected by surface characteristics of the materials. The adsorption capacities for raw sediment and heat treated sediment were 2.12 and 2.19mg NO3-N/g, respectively, which were higher than others, indicating that the sediment activated by heat could be used as a material for the improvement of nearshore water quality.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.311-316
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• 2005

A laboratory study on the adsorption of nitrate contaminated in nearshore water using various materials including several types of dredged sediments(ST) and yellow clays(YC), which are activated by hear(HT), bioleaching for heavy metal removal(BL) and neutralization(NR) was performed. The equilibrium time of the adsorption for the sediment bioleached and treated by heat(BL-HT-ST) was only 17min. which was faster than the sediment bioleached, neutralized and treated by heat(BL-NR-HT-S) (25min) or the sediment treated by the bioleaching process(BL-ST)(27min), but longer equilibrium times for yellow clay(YC) or heat treated yello clay(HT-YC) were required. The adsorption processes of nitrate in sea water for tested material could be described by Freundlich isotherm, but were significantly affected by surface characteristics of the materials. The adsorption capacities for raw sediment and heat treated sediment were 2.12, 2.19mg $NO_{3}$-N/g, respectively, which were higher than others, indicating that the sediment activated by heat could be used as a material for the improvement of nearshore water quality.