• 한국지하수토양환경학회지:지하수토양환경
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• 제18권1호
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• pp.85-93
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• 2013

This study is conducted to evaluate the leaching of contaminants from mine tailing by natural water and finally to estimate the leaching and transportation of heavy metal contaminants by rainfall. In order to identify contaminated heavy metal of soil, 17 soil, 2 tailing and 2 waste dump and 2 control samples were taken at mine area and analyzed total metal contents. The leaching experiments were conducted using distilled water. Cu, Pb, Zn was extracted from the reddish mine tailing in a short period time, especially the extraction rate of Cu (45.0%) was highest. The contaminants were leached from the yellowish mine tailing within an hour and the leaching rate of Cd (42.0%) and Zn (17.2%) were relatively high. The reddish soil from the waste dump showed leaching of Cu (5.1%), Pb (4.0%) and Zn (3.3%), however the leaching rate was low except Mi (14.2%). From the yellowish soil sampled from the dumping site, the leaching of Cu (8.2%) and Ni (9.7%) was high while the leaching of Zn (0.2%) were relatively low.

• 광물과 암석
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• 제33권3호
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• pp.243-250
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• 2020

본 연구의 목적은 선상에서 열수광물 내 Au를 효과적으로 용출하기 위한 마이크로웨이브-차아염소산 용출의 적용 가능성을 파악하는 것이다. 비교용출실험은 마이크로웨이브 질산용출의 유(T1)/무(T2)에 따른 Au 용출율의 영향을 확인하였다. 또한, 기계적 교반에 의한 전통적인 용출(T3)과 마이크로웨이브 용출에 따른 Au 용출율을 비교하였다. 마이크로웨이브 질산용출결과(고액비; 10%, 용출온도; 90℃, 용출시간; 20분), 금속의 용출율은 As>Pb>Cu>Fe>Zn 순으로 높게 나타났으며, 용출잔사 내 Au의 함량은 33.77 g/ton에서 60.02 g/ton으로 증가하였다. 염화물 용매제를 이용한 비교용출실험 결과, Au의 용출율은 T1(61.10%)>T3(53.30%)>T2(17.30%)순으로 높게 나타났다. 따라서, 해수를 이용하여 제조 가능하고 용출과정에서 발생되는 염소 가스를 포집하여 재이용 가능한 염화물은 Au용출을 위한 최적의 용매제로 예상된다. 또한 마이크로웨이브를 적용함으로써 시간, 효율 및 에너지 측면에서 효과적일 것으로 판단되어진다.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1175-1184
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• 2022

The pore structure of uranium-bearing sandstone is one of the critical factors that affect the uranium leaching performance. In this article, uranium-bearing sandstone from the Yili Basin, Xinjiang, China, was taken as the research object. The fractal characteristics of the pore structure of the uranium-bearing sandstone were studied using mercury intrusion experiments and fractal theory, and the fractal dimension of the uranium-bearing sandstone was calculated. In addition, the effect of the fractal characteristics of the pore structure of the uranium-bearing sandstone on the uranium leaching kinetics was studied. Then, the kinetics was analyzed using a shrinking nuclear model, and it was determined that the rate of uranium leaching is mainly controlled by the diffusion reaction, and the dissolution rate constant (K) is linearly related to the pore specific surface fractal dimension (D_S) and the pore volume fractal dimension (D_V). Eventually, fractal kinetic models for predicting the in-situ leaching kinetics were established using the unreacted shrinking core model, and the linear relationship between the fractal dimension of the sample's pore structure and the dissolution rate during the leaching was fitted.

• 한국응용과학기술학회지
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• 제20권4호
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• pp.324-331
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• 2003

Particulate leaching method for the preparation of porous PLLA scaffolds was carried out and especially, the effect of PLLA/$CHCl_3$ solution concentration on the salt leaching rate and the pore structure of PLLA scaffolds were considered. It was found that maintaining lower PLLA/$CHCl_3$ concentration and higher $CHCl_3$ evaporation temperature in the preparation of PLLA/NaCl mixtures resulted in the enhancement of salt leaching rat e and higher porosity. This is understood that those conditions could minimize the formation of dense PLLA layer on the surface of PLLA/NaCl mixture as well as introducing better porosity on the surface. Higher salt leaching temperature accelerated the salt leaching rate but it seems that there is no influence on the porosity of PLLA scaffolds.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4033-4041
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• 2021

To better understand the permeability of uranium sandstone, improve the leaching rate of uranium, and explore the change law of pore structure characteristics and blocking mechanism during leaching, we systematically analyzed the microstructure of acid-leaching uranium sandstone. We investigated the variable rules of pore structure characteristics based on nuclear magnetic resonance (NMR). The results showed the following: (1) The uranium concentration change followed the exponential law during uranium deposits acid leaching. After 24 h, the uranium leaching rate reached 50%. The uranium leaching slowed gradually over the next 4 days. (2) Combined with the regularity of porosity variation, Stages I and II included chemical plugging controlled by surface reaction. Stage I was the major completion phase of uranium displacement with saturation precipitation of calcium sulfate. Stage II mainly precipitated iron (III) oxide-hydroxide and aluminum hydroxide. Stage III involved physical clogging controlled by diffusion. (3) In the three stages of leaching, the permeability of the leaching solution changed with the pore structure, which first decreased, then increased, and then decreased.

• 한국환경보건학회지
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• 제20권4호
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• pp.72-79
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• 1994

This study was performed to improve many problems of leaching test of industrial waste sludge analysis. We analyze sludges by variation of leachant, pH and leaching time.The results were as follows: 1. As leaching at pH 5.8 by our leaching test without control of pH during leaching, the leaching rates were very low as below 1%. 2. As leaching at pH 5.8 continuously by hydrochloric acid every 2 hour, the leaching rates were higher than before 1. 3. As leaching at pH 5.0 continuously by acetic acid every 2 hour, the leaching rates were higher than 1, 2. 4. The variations of leaching rate by leaching time were smaller increase after 10 hours than before. 5. It will be recommendable that the pH of leachant maintain constantly during leaching as level of acid rain, and the acetic acid is more effective than hydrochloric acid as leachant.

• 환경위생공학
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• 제13권2호
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• pp.121-127
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• 1998

This study was to understand leaching characteristics with pH controlling agents and Temp. control, and investigate leaching characteristics with pH control from opening a leaching test to an end for reassessing leaching test of heavy metals with environmental conditions in landfill. Because leaching of heavy metals was increased in low pH, pH must control for leaching in existing leaching test. Generally, regulation time(6hr) of leaching was confirmed reasonablely, except for Cu in plating sludge. In pH controlling solution, there was nearly not difference between Acetic acid and HCl and if considering Cu, the former was appropriate. In a part of heavy metal, leaching rate was increased in high Temp., and normal Temp. in existing leaching test would be revaluated.

• 자원리싸이클링
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• 제24권6호
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• pp.24-30
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• 2015

본 연구에서는 페로망간 제조공정에서 발생한 집진분의 황산침출에 대하여 조사하였다. 황산의 농도, 반응온도, 교반속도, 입자크기 및 고-액비가 집진분 중의 Mn과 Fe의 침출에 미치는 영향에 대하여 검토하였다. Mn과 Fe의 침출속도는 황산의 농도가 높고 반응온도가 높을수록 높아졌다. 실험결과를 입자수축모델을 이용하여 검토한 결과 침출반응은 입자표면에서의 화학반응에 의해서 율속되는 것으로 생각된다. Mn과 Fe 침출반응의 활성화에너지는 각각 79.55 kJ/mol과 77.48 kJ/mol로 계산되었다.

• 한국광물학회지
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• 제26권1호
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• pp.1-8
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• 2013

티오요소를 사용하여 삼조광업 정광으로부터 은을 친환경적으로 용출시키고자 하였다. 삼조광산의 광석은 황철석, 황동석, 방연석, 유비철석, 섬아연석 등과 같은 광석광물들로 구성되어 있다. 티오요소 용출실험에는 $750^{\circ}C$에서 소성시킨 소성정광을 사용하였다. 다양한 실험조건으로 용출실험을 수행한 결과, 본 실험 조건 중 가장 높은 은 용출율이 나타나는 조건은 티오요소 농도 0.8 g일 때, 황산 제2철 0.425 g일 때, 그리고 용출온도 $60^{\circ}C$일 때였다. 광액농도 10%일 때 은 용출율 91.5%를 얻었다. 그러나 고체 잔유물에 대해서 XRD 분석을 수행한 결과, 은 용출율이 가장 높은 고체 잔유물들에서 황철석, 방연석, 적철석 등이 나타났다. 이러한 결과로 미루어 볼 때 고체 잔유물에 포함된 은은 회수하지 못하고 소실될 것으로 예상된다.

• 자원리싸이클링
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• 제19권5호
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• pp.25-30
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• 2010

CMSX-4 초내열합금의 순환활용을 위한 습식제련기술 개발의 일환으로 영신에서의 니켈, 코벨트, 크롬, 알루미늄 등 주요 구성 금속성분들의 침출 특성을 조사하였다. 염산농도에 따른 합금시료 내 주요 금속성분들의 침출율은 염산농도가 높아짐에 따라 증가하였으나, 3 M 이상에서는 둔화되었다 염산농도 4 M, 고액비 10 g/L, 침출시간 60 분 조건에서 침출온도가 높아짐에 따라 침출율은 급격히 증가하였으며, $90^{\circ}C$에서 니켈 93.2%, 알루미늄 89.9%, 코발트 80.4%, 크롬 79.1%의 침출율을 나타내었다. 한편 침출 초기에는 니켈과 알루미늄의 침출속도가 빠르고 60 분 이후 급격히 둔화되는 형태를 보인 반면 코발트와 크롬은 침출이 느리고 60 분 이후의 감소율만 상대적으로 적었다. 120 분 경과 시 주요 금속원소들의 침출율은 모두 99% 수준에 도달하였다. 고액비가 높아지면 침출율은 서서히 감소하였으며, 니켈과 알루미늄이 코발트와 크롬에 비하여 침출율 감소가 적었다. 염산농도 4 M, 침출온도 $90^{\circ}C$, 침출시간 120 분의 조건에서 고액비 125 g/L 이하의 조건이 주요 금속 성분의 침출에 효과적임을 확인하였으며, 이는 CMSX-4 합금의 금속학적 조직구조와 관련이 있는 것으로 생각된다.