• Mineral and Industry
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• v.23
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• pp.26-31
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• 2010

희토류 정광으로부터 첨단산업 원료소재로 수요가 급증하고 있는 고순도 희토류 소재를 제조하기 위한 가장 첫 공정은 침출공정이다. 즉, 희토류 정광으로부터 원소별 희토류 성분을 분리하기 위해서는 용액상태로 전환이 필요한데, 이때 일반적인 산 및 알카리 용액에는 희토류 성분은 침출이 되지 않으므로 강산 또는 강 알카리 조건에서 희토류 정광을 침출 가능한 형태로 변환 시켜주는 분해공정이 선행되며 이후 산 침출에 의해 희토류 성분을 침출하게 된다. 본 고에서는 대표적인 희토류 광물인 모나자이트와 바스트나사이트, 그리고 이 광물의 혼합물 형태로 생산되는 혼합광물에 대한 분해 및 침출공정을 소개하고자 한다.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.668-673
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• 2008

The objective of this study is to optimize the leaching conditions of sequential leaching and extracting processes for selective Ni recovery from spent Ni-Mo-based catalyst. The selective Ni recovery process consists of two processes of leaching and extracting process. In this 2-step process, Ni component is dissolved from solid spent Ni-Mo-based catalyst into leaching agent in leaching process and sequentially extracted to Ni complex with an extracting agent in the extracting process. The solutions of nitric acid ($HNO_3$), ammonium carbonate ($(NH_4)_2CO_3$) and sodium carbonate ($Na_2CO_3$) were used as a leaching agent in leaching process and oxalic acid was used as an extracting agent in extracting process. $HNO_3$ solution is the most efficient leaching agent among the various leaching agent. Also, the optimized leaching conditions for the efficient and selective Ni recovery were the leaching temperature of $90^{\circ}C,\;HNO_3$ concentration of 6.25 vol% and elapsed time of 3 h. As a result, Nickel oxalate having the highest yield of 88.7% and purity of 100% was obtained after sequentially leaching and extracting processes under the optimized leaching conditions.

• Resources Recycling
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• v.21 no.5
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• pp.3-17
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• 2012

Selective leaching processes for copper, gold, nickel, and cobalt have been investigated because there is an advantage of ammoniacal hydrometallurgy that metal such as copper could be selectively extracted restricting the dissolution of iron or calcium. In the present article, the studies for selective ammoniacal leaching of copper from motor scraps and waste printed circuit boards (PCBs), for ammoniacal leaching of gold to decrease the amount of cyanide used or to substitute cyanide by thiosulfate, and for ammoniacal leaching to recover nickel and cobalt from nickel oxide ore and intermidiate obtained from manganese nodule treatment process were summarized and further studies were proposed for domestic technology development for ammoniacal hydrometallurgy processes.

• Resources Recycling
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• v.26 no.1
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• pp.37-42
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• 2017

It has been reported that aqueous indirect carbonation process of calcium silicate mineral could be one of the most promising methods for $CO_2$ sequestration. The process consists of two main steps, extraction of Ca from calcium silicate and carbonation of the extracted solution by $CO_2$. Many types of acids such as HCl and $HNO_3$ can be used in the extraction step of the process. In the case of using aqueous acetic acid solution as the extraction solvent, acetic acid can be reproduced at the carbonation step of the extracted solution by $CO_2$ and recycled to extraction step for reuse it. Industrial by-products such as iron and steel slags are potential raw materials of the indirect carbonation process due to their high contents of calcium silicate. In this study, in order to examine the extraction efficiency of domestic electric arc furnace steel slag by aqueous acetic acid solution, extraction experiments of the slag were performed by using the aqueous acetic acid solutions of varying extraction conditions ; acetic acid concentrations, extraction temperatures and times.

• Journal of the Korea Convergence Society
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• v.7 no.1
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• pp.155-160
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• 2016

The convergence process utilized both leaching and ion exchange techniques has been investigated for the heavy metals removal in the abandoned mine of Chungyang Province, Korea. The contaminated soil samples by heavy metals from Samkwang mine were analysed by statistical analyses. The highly contaminated soils was initially separated by the flotation process. The selectivity indices were increased with increasing flotation reagents. The selectivity of separation was then improved by the use of both leaching and ion exchange processes in order to extract the heavy metals. The results of this study showed that the higher the sulfuric acid concentration, the leaching rate of heavy metals was increased. The lecheate then was removed by the ion exchange method. The anticipating results might imply that convergence process utilized both leaching and ion exchange techniques would somehow apply for the removal of heavy metals in the abandoned mine.

• 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.26 no.1
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• pp.3-10
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• 2017

The special properties of silver are often indispensable in the manufacture of advanced materials. Therefore, it is of importance to develop a process to recover silver which is necessary for the production of advanced materials from diverse resources. In this manuscript, the developed processes for the leaching of silver from diverse resources are reviewed. For this purpose, the advantages and disadvantages of using some inorganic acids (nitric and sulfuric acid) and their mixture with other oxidizing agents (ozone, oxygen, hydrogen peroxide and ferric ion) were investigated. Moreover, the leaching of silver with thiourea and thiosulfate was compared over those by inorganic acids in terms of environmental effect.

• Resources Recycling
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• v.31 no.4
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• pp.40-48
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• 2022

In waste lithium iron phosphate (LFP) batteries, the cathode material contains approximately 4% lithium. Recycling the constituent elements of batteries is important for resource circulation and for mitigating the environmental pollution. Li contained in the waste LFP cathode powder was selectively leached using persulfate-based oxidizing agents, such as sodium persulfate, potassium persulfate, and ammonium persulfate. Leaching efficiency and waste LFP powder properties were compared and analyzed. Pulp density was used as a variable during leaching, which was performed for 3 h under each condition. The leaching efficiency was calculated using the inductively coupled plasma (ICP) analysis of the leachate. All types of persulfate-based oxidizing agents used in this study showed a Li leaching efficiency over 92%. In particular, when leaching was performed using (NH₄)₂S₂O₈, the highest Li leaching percentage of 93.3% was observed, under the conditions of 50 g/L pulp density and an oxidizing agent concentration of 1.1 molar ratio.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.164-167
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• 2001

본 연구에서는 포항제철소에서 제철부산물로 발생되는 제강분진을 전처리 없이 산화촉매로 사용하여 김포 수도권 매립지의 침출수 처리공정에서 펜톤산화조에 유입되는 원수를 대상으 로 과산화수소를 이용한 연속식 산화처리 실험을 수행하였다. 먼저 회분식 실험결과를 바탕 으로 최적 반응조건에서 lab-scale 연속식 기초반응실험과 자체 설계.제작한 연속산화공정에서의 처리실험을 수행하였다. 또한 기존의 펜톤산화공정에서 Fe 공급원으로 사용되고 있는 FeSO$_4$.7($H_2O$)와의 반응성 비교실험도 수행하였다. 반응기간동안 일정 pH를 유지하기 위해 pH controller를 사용하였으며 침출수 수질은 CODcr로 나타내었다. 반응 pH 3.5, 체류시간 1 hr, 과산화수소 주입량 1,500mg/1에서 제강분진과 FeSO$_4$.7($H_2O$)를 각각 주입하여 수행한 연속처리 기초실험에서는 제강분진을 산화반응촉매로 사용한 경우에 침출수CODcr 처리율 62%, 과산화수소의 분해율 52%를 나타내었다. FeSO$_4$.7($H_2O$)를 산화반응 촉매로 사용한 경우에는 약 65-70%정도의 다소 높은 처리효율을 나타낸 반면에 과산화수소의 소비량은 제강분진의 경우보다 약 20%이상의 높은 값을 나타내었다. 연속산화공정 실험에서는 운전 3시간 이후에 유출수 중의 CODcr과 $H_2O$$_2$의 농도가 안정된 값을 나타내었다. 이 때 산화 반응조의 침출수 CODcr 제거효율은 약 43%이었으며, 처리수의 농도는 현재의 침출수 방류기준 이하로 나타났다. 결론적으로 침출수의 연속식 산화처리 실험결과, 처리효율과 경제성에서 제강분진의 산화촉매활용 공정의 개발 가능성이 매우 높은 것으로 나타났다.ell에 의해 완전분해 되었으며, 함께 존재시 TC는 Fe$^{\circ}$만으로는 분해가 되지 않았지만 cell에 의해 완전분해 되었으며, 함께 존재시 TCE분해에 저해작용을 미치는 것으로 나타났다.술의 첨가가 요구되고 있다. 따라서, 산성광산배수 오염지대에 대해 획일적으로 같은 처리방법을 채택하여 사용하는 것보다 각 지역 또는 광산산성폐수가 유출되어 나오는 광산폐기물의 특성 등을 고려하여 거기에 맞는 기술들을 복합적으로 또는 단독으로 사용하되 처리방법 채택 시 신중을 기할 것이 요망된다.정시에는 SeaWiFS 위성과 관련된 global algorithms 중에서 490nm와 555nm의 복합밴드를 포함하는 OC2 알고리즘(ocean color chlorophyll 2 algorithm)을 사용하는 것이 OC2 series 및 OC4 알고리즘보다 좋은 추정 값을 도출할 수 있을 것으로 기대된다.환경에서는 5일에서 7월에 주로 이 충체의 유충이 발육되고 전파되는 것으로 추측되었다.러 가지 방법들을 적극 적용하여 금후 검토해볼 필요가 있을 것이다.잡은 전혀 삭과가 형성되지 않았다. 이 결과는 종간 교잡종을 자방친으로 하고 그 자방친의 화분친을 사용할 때만 교잡이 이루어지고 있음을 나타내고 있다. 따라서 여교잡을 통한 종간잡종 품종육성 활용방안을 금후 적극 확대 검토해야 할 것이다하였다.함을 보이고 있다.X> , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경우 Dv값이 제일 작았다. 바. 본 연구의 목적중의 하나인 인체유해 중금속이온인 Hg(II), Cd(II)등이 NaCl같은 염화물

• Clean Technology
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• v.28 no.2
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• pp.103-109
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• 2022

Nd-Fe-B waste permanent magnet contains about 20~30% rare earth elements and about 60~70% iron elements, and the rare earth and iron components were recovered through sulfuric acid leaching and fractional crystallization. Oxidation roasting was not performed for separation and recover of the rare earth and iron elements. The leaching characteristics were confirmed by using as variables the sulfuric acid concentration and the mineral solution concentration ratio. Sulfuric acid leaching was carried out for 3 hours for each sulfuric acid concentration. The leached solid phase was characterized for its crystalline phase, composition, and quantitative components by XRD and XRF analysis, and the filtrate was analyzed for components by ICP analysis. With sulfuric acid leaching at 3M sulfuric acid concentration, neodymium compounds were formed, the iron content was the least, and the recovery rate was high. After the filtrate remaining after sulfuric acid leaching was subjected to fractional crystallization through evaporation and concentration, the neodymium component was found to be concentrated 7.0 times and the iron component 2.8 times. In this study, the recovery rate of waste permanent magnets through sulfuric acid leaching and a fractional crystallization method without an oxidation and roasting process was confirmed to be about 99.4%.