• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2005년도 추계정기총회 및 제26회 학술발표대회 고분자리싸이클링기술 특별심포지엄
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• pp.304-307
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• 2005

Printed circuit boards (PCBs) of the printer are composed of various organic and inorganic compounds as well as metals and alloys. This study was conducted to recover valuable metals from used PCBS by physical separation and leaching. The PCBs was crushed, sieved, classified by zig zag classifier and magnetic constituents were removed by the magnetic separation. The non-magnetic constituents of sizes between 1.2 and 0.6 mm especially containing high quantity of Cu (e.g. 83% on metal base and 31% on total base) were used for the leaching experiment. The effect of the nature and concentration of acids and reaction temperature were investigated. The Cu leaching rate to 98.5% in 2M nitric acid, pulp density 100g/L, $90^{\circ}C$, 300rpm, 1hr leaching.

• 자원환경지질
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• 제32권1호
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• pp.53-62
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• 1999

The possibility of heavy metal pollution by contaminated roadside soils was studied under controlled conditions. The soil samples from roadside and those from a retention pond consisting of settling particles were characterized by the XRD analyses and the sequential extraction experiments. Characterization by sequential extraction, for roadside soil indicates elevate total concentrations of heavy metals. The leaching behavior of the samples under different pH and time conditions were also studied. Differences between both types of samples result mainly from the buffering effect of carbonates, present in roadside soils and lacking from settling particles. Acid leaching of the settling particles is equivalent to the sum of FI+FII+FIII, while the amounts leached from roadside soil are lower probably from kinetic reasons. The buffering effects of carbonates were found to greatly delay the onset of the leaching reactions and the extent of dissolution in most metals except for Ca and Mn. The study of leaching kinetics at pH of 6.5 and 5 showed that Cd and Zn reached the maximum possible concentration within 3 days, while Pb did not show any sign of dissolution at both ph values. The absolute amounts of dissolved Cd and Zn increased by 7 to 9 times by decreasing the pH from 6.5 to 5, indicating slightly acidified rain may result in significant metal dissolution. As deduced from both sequential extraction and leaching experiments, the relative mobility of heavy metals is found to be : Mn=Cd>Zn>>Pb>Fe, in spite of large differences in heavy metal contents and localizations.

• Environmental Engineering Research
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• 제10권3호
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• pp.112-121
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• 2005

The effectiveness of quicklime-based stabilization/solidification (S/S) in immobilizing lead (Pb) was assessed by performing semi-dynamic leaching tests (ANS16.1). In order to simulate landfill leaching conditions, the ANS 16.1 test was modified by using 0.014 N acetic acid (pH = 3.25) instead of distilled water. Artificial soil samples as well as field soil samples contaminated with Pb were tested. The effectiveness of quicklime treatment was evaluated by determining diffusion coefficients ($D_e$) and leachability indices (LX). A model developed by de Groot and van der Sloat was used to elucidate the controlling Pb leaching mechanisms. Overall, upon quicklime treatment Pb leachability was significantly reduced in a]l of the samples tested. The mean LX values were higher than 9 for an artificial soil sample containing 30% kaolinite treated with 10% quicklime and for a field soil sample treated with 10% quicklime, which suggests that S/S treated soils can be considered acceptable for "controlled utilization". Moreover, quicklime treatment was more effective in artificially contaminated soil with high kaolinite content (30%), indicating the amount of clay plays an important role in the success of the treatment. The controlling Pb leaching mechanism was found to be diffusion, in all quicklime treated samples.

• 자원리싸이클링
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• 제29권1호
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• pp.81-88
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• 2020

발광다이오드는 많은 양의 갈륨과 인듐을 함유하고 있어, 폐발광다이오드로부터 이들 원소의 회수는 최근 많은 관심을 받은 연구 분야이다. 본 연구에서는 폐발광다이오드에 포함된 질화갈륨으로부터 갈륨과 인듐을 회수하고자 시도하였다. 전체 공정은 물성분석, 알칼리배소, 침출의 세 단계로 구성되었다. 화학성분 분석결과 폐발광다이오드의 경우, 70.32% 갈륨, 5.31% 규소, 2.27% 알루미늄 및 2.07% 인듐이 함유됨을 확인하였다. 두 번째 단계인 알칼리배소 공정은 탄산나트륨과 함께, 900℃하에서 3시간의 반응이 최적 조건인 것으로 확인되었고, 이 공정을 통해 질화갈륨이 질화산화물로 변화되었다. 마지막은 침출 단계로서, 산의 종류 및 농도, 고액비, 반응시간에 따른 변화를 조사하여, 최적조건을 확립하였다. 최적조건은 반응온도 25℃ 및 2.0 M의 염산 환경에서 30 ml/g의 고액비와 반응시간 32분으로 나타났으며, 그 때의 침출 효율은 갈륨 96.88%와 인듐 96.61%로 나타났다.

• 자원리싸이클링
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• 제14권6호
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• pp.28-36
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• 2005

황산을 사용하여 폐양극활물질, $LiCoO_{2}$로부터 코발트를 침출한 뒤 용매추출법으로 분리하여 회수하는 습식제련공정을 개발하였다. 최적침출조건은 황산농도 2.0 M, 과산화수소수 첨가량 5 $vol.\%$, 침출온도 $75^{\circ}C$, 침출시간 30 min., 초기정액농도 100 g/L 이었으며, 코발트와 리튬의 침출율은 각각 $93\%$와 $94.5\%$이었다. 초기 pH 5.0, 유기상과 수용액상의 상비 1.6 : 1, 추출단수 1단의 조건에서 1.5 M Cyanex 272를 추출제로 사용하여 44.72 g/L 코발트와 5.43 g/L 리튬을 함유하는 황산침출액으로부터 $85\%$의 코발트를 추출하였다. 추출잔액에 남아있는 코발트는 Na-Cyanex 272농도 0.5M, 초기 pH 5.0, 유기상과 수용액상의 상비 1:1의 조건에서 완전히 추출되었다. 폐 $LiCoO_{2}$의 황산침출-Na-Cyanex 272에 의한 코발트의 용매추출-탄산소다용액에 의한 리튬의 세정-황산용액에 의한 코발트의 탈거 등 일련의 습식제련공정을 이용하여 폐$LiCoO_{2}$로부터 순도 $99.99\%$이상의 황산코발트용액을 회수할 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.193-197
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• 2001

This study was carried out to recover gold, silver and other valuable metals from the printed circuit boards (PCB) of waste computers. PCB samples were crushed to under 1mm by a shredder and initially separated into 30% conducting and 70% non-conducting materials by an electrostatic separator. The conducting materials, which contained the valuable metals, were then used as the feed material for magnetic separation where it was found that 42% was magnetic and 58% non- magnetic. The non-magnetic materials contained 0.227mg/g Au and 0.697mg/g Ag. Further leaching of the non-magnetic component using 2.0M sulfuric acid and 0.2M hydrogen peroxide at 85$^{\circ}C$ extracted more than 95% copper, iron, zinc, nickel and aluminium. Au and Ag were not extracted in this solution, however, more than 95% of Au and 100% of Ag were selectively leached with a mixed solvent (0.2M ammonium thiosulfate, 0.02M copper sulfate, 0.4M ammonium hydroxide). Finally, the residues were reacted with a NaCl solution to leach out Pb while sulfuric acid was used to leach out Sn. Recoveries reached 95% and 98% in solution, respectively.

• 대한금속재료학회지
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• 제48권1호
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• pp.62-70
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• 2010

Leaching and solvent extraction experiments have been performed to develop a hydrometallurgical process for the recovery of nickel and cobalt from nickel laterite ore with high magnesium content. Most of the nickel and magnesium in the laterite ore dissolved at leaching conditions of $80^{\circ}C$ and 100 g/L sulfuric acid concentration. while half of the cobalt and iron were leached at the same conditions. Solvent extraction experiments were carried out with D2EHPA and saponifed D2EHPA from a synthetic solution containing Ni, Co, and Mg. The extraction percentage of Co, Mg. and Ni by D2EHPA was very low in a pH range of 4.4 to 7.3. while the extraction percentage sharply increased by using saponified D2EHPA. The stripping percentage of the metals from the saponified D2EHPA increased with sulfuric acid concentration and reached 99.9% at 1 M $H_2SO_4$ solution.

• 한국잠사곤충학회지
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• 제51권2호
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• pp.164-172
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• 2013

이 연구는 뽕잎을 전통방식의 당침 추출액과 Lactobacillus plantarum TO- 2100 유산균을 이용한 유산발효 추출액의 기능성 품질 특성을 조사하였다. 당침 추출액은 12주 동안 추출하였으며, 유산발효 추출액은 8주간 추출하였다. 당침 추출액 및 유산발효 추출액의 수율은 각각 27% 와 166% 였으며, 당 함량은 각각 43 $^{\circ}Brix$와 33 $^{\circ}Brix$였다. pH와 총 산도는 4.6, 0.45% 와 3.6, 1.17%였다. 유산발효 추출액의 유산균 생균수는 $1.2{\times}10^{10}$ $CFU/m{\ell}$으로 당침 추출액의 $2.8{\times}10^2$ $CFU/m{\ell}$ 보다 월등히 많았다. 유산발효 추출액이 amylase, cellulase, pectinase, protease 등 분해효소의 활성을 보인 반면, 당침 추출액은 분해효소의 활성을 나타내지 않았다. 유기산의 경우 malic acid, acetic acid, citric acid의 함량은 당침 추출액이 높은 반면, lactic acid 의 함량은 유산발효 추출액이 2.6배 높았다. 당침 추출액의 유리당은 glucose (200.93mg/g), fructose (236.32mg/g), sucrose (18.41mg/g) 등 GI값이 높은 단당으로 구성된 반면, 유산발효 추출액에서는 유리당이 검출되지 않았다. 기능성 성분인 polyphenol, anthocyanin 및 당질대사 저해물질인 piperidine alkaloid의 함량 또한 유산발효 추출액이 당침 추출액보다 높았다. 당질대사의 주 효소인 ${\alpha}$-glycosidase의 활성을 당침 추출액이 3.4% 저해한 반면 유산발효 추출액은 16.2% 저해 활성을 보였다. 이 결과로부터 전통방식의 당침 추출법에 비해 유산발효 추출법이 뽕잎의 수율 향상 및 기능성 성분의 함량 증진에 더 효과적이며, 이로 인한 대사기능장애의 예방 및 기능증진에 더 유효할 것으로 사료된다.

• 미생물학회지
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• 제11권2호
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• pp.69-78
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• 1973

In order to investigate the distribution of an iron-oxidizing bacterium, Ferrobacillus ferrooxidans in Korea, the authors had carried out the chemical and microbiological analysis of mine water. The results obtained were as follows : 1. Ferrobacillus ferrooxidans concerned to leaching was isolated from 10 copper mine water out of 46 sites in Korea. 2. As the results of bacterial oxidation, the contents of sulfuric acid, ferric sulphate and copper in the bacteria-bearing solutions were higher than those in bacteria-free solutions.

• 한국결정성장학회지
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• 제18권6호
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• pp.232-236
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• 2008

최근 실리콘 원료의 부족에 따른 가격상승으로 인하여 99.9999% 이상의 순도를 지닌 폴리 실리콘을 더 저렴하게 제조하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 순도 99%의 금속급 실리콘(MG-Si)을 원료로 산처리와 일방향 응고를 통해 고순도로 정제하는 연구를 수행하였다. MG-Si 럼프를 플레너터리 밀로 분쇄한 후 HCl/$HNO_3$/HF 산 수용액에서 처리하였다. 그 결과 Al, Fe, Ca, Mn 등과 같은 금속 불순물들의 실리콘 내 함량이 크게 감소하면서 실리콘의 순도는 99.995%까지 향상되었다. 정제된 실리콘 분말을 성형한 후 HEM로를 이용하여 용융시킨 뒤, 일방향 응고를 통하여 잉곳을 제조하였다. 성장시킨 다결정 실리콘 잉곳은 $0.3{\Omega}{\cdot}cm$의 비저항과 $3.8{\mu}{\cdot}sec$의 열 운반자 소멸시간(minority carrier life time)을 나타내었다.