• 자원리싸이클링
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• 제1권1호
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• pp.58-68
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• 1992

아연을 함유하고 있는 산업폐기물로부터 첨단산업의 소재원료인 미립의 고순도 ZnO 분말을 아연제련의 용매추출 공정에서 직접 합성할 수 있는 방법을 개발하고자 하였다. 아연 함량이 55%인 선재산업의 폐기물을 황산으로 침출하여 아연을 추출하였다. 함아연 용액에서 철분을 침전시켜 제거한 후 D2EHPA를 추출제로 사용하는 용매추출에 의해 아연이온을 유기상으로 추출하여 정제한 뒤 oxalic acid와 같은 침전제를 사용하여 유기상의 아연 이온을 precipitation stripping 법으로 탈거, 침전시켜 $ZnC_2O_4$ 분말을 합성하였으며 이를 해소하여 99.9% 이상의 ZnO 분말을 제조하였다. 황산농도, 침출시간, 황액농도가 아연의 침출율에 미치는 영향과 용매추출시 용액의 산도에 따른 아연과 불순물의 추출거동을 조사하여 최적정제조건을 얻었다. 또한 oxalic acid의 농도, 온도, 계면활성제의첨가, 침전시간 등이 생성된 $ZnC_2O_4$ 분말의 형상과 입자크기 및 분포에 미치는 영향에 대해 조사하였다.

• 한국재료학회지
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• 제27권12호
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• pp.672-678
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• 2017

In the production of zirconium cladding tube, a pickling acid solution is used to remove surface contaminants, which generates tons of pickling acid waste. The waste pickling solution is a valuable resource of Hf-free Zr. Many studies have investigated separating the Hf-free Zr source from the waste pickling acid. The results showed that $Ba_2ZrF_8$ precipitates prepared from the waste pickling acid were useful as an electrolyte for the electrorefining of Zr in molten salt. In the present work, electrorefining was performed in a $Ba_2ZrF_8-LiF$ binary electrolyte to recover Zr from a Hf-free CuZr ingot anode prepared by electroreduction. Before electrorefining, two pretreatments are performed. First, electrolyte melting was carried out to determine the eutectic temperature, and second, the electrolyte was treated to eliminate impurities, mainly hydride. After electrorefining, the cathode deposits were analyzed by $O_2$ gas analyzer and SEM-EDX to explore the possibility of recovering nuclear-grade Zr metal. Moreover, the anode was analyzed by SEM-EDX to determine the Zr dissolution depth.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2015년도 추계학술논문요약집
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• pp.465-466
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• 2015

In this study, different amount of (fe(0)) were dissolve into different strength of phosphoric ($H_3PO_4$) acid and the optimum solubility was observed at 0.89M Fe(0) into 4M of $H_3PO_4$ acid. Different concentration of oxalic acid was added to determine the optimum precipitated condition. The dissolution kinetics of Fe(0) into $H_3PO_4$ acid was investigated at $40-50^{\circ}C$. The optimum Fe-oxalate precipitate was dried and thermal decomposition using DSC-TG was conducted. Approximately 52 wt(%) of oxalic acid was removed at $300^{\circ}C$. Iron oxides such as magnetite and hematite that may be formed on the surface of nuclear waste were also dissolved into the $H_3PO_4$ acid and the optimum solubility for magnetite is 0.005M while that for hematite is 0.02M in 8M $H_3PO_4$ acid, respectively.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.421-426
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• 2001

The pneumatic classification and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in waste fluorescent lamp. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by pneumatic classification. After pneumatic classification of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth components were separated as hydroxide and oxalate precipitations. The experimental results obtained are summarized as follows: (1) In classification process, rare earth components in phosphor sludge were concentrated to 29.3% from 13.3%, and its yield was 32.9%. (2) In leaching process, sulfuric acid solution was more effective one as a leaching solvent of rare earth component than other solutions. Y and Eu components in phosphor sludge were dissolved in sulfuric acid solution of 1.5 k㏖/㎥, and other rare earth components were rarely dissolved in leaching solution. Leaching degrees of Y and Eu were respectively 92% and 98% in the following optimum leaching conditions; sulfuric acid concentration is 1.5 k㏖/㎥ , leaching temperature 343 K, leaching time 3.6 ks and pulp concentration 30 kg/㎥. (3) Y and Eu components of phosphor sludge contained in waste fluorescent lamp were, effectively recovered by three processes of pneumatic classification, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finally about 65 %, and its purity was 98.2%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.432-436
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• 2001

In this study, calcium sulfate(gypsum) powder was obtained using waste sulfuric acid and stainless refinery sludge by- produced from chemical reagent and the iron industry, by the neutralization of waste sulfuric acid. As variables for the experiment the mole ratio of the H$_2$SO$_4$ : Ca(OH)$_2$, the pH, the reaction temperature and time, the amount of catalyst were used. The crystal shape and microstructure of obtained powder were observed by XRD and SEM, and the thermal property was investigated by DTA. As the NaCl is added 0~20wt% as a catalyst to the H$_2$SO$_4$ : Ca(OH)$_2$, system it can be found that the crystal shape goes through the processes as follows : gypsum dihydratlongrightarrowgypsum hemihydrate＋gypsum dihydratelongrightarrowgypsum hemihydrate. And gypsum hemihydrate is $\beta$-type as the result of DTA. As waste sulfuric acid and stainless refinery sludge were used, the pH of reacted solution (which was 0.8) was rapidly raised up to 8~9 by the addition of stainless sludge and gypsum dihydrate was produced as a by-product. Therefore, it was found that stainless refinery sludge is sufficiently applicable for the neutralization of waste sulfuric acid.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.209-212
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• 2002

Main radionuclides of the soil waste stored in Korea Atomic Energy Research Institute are Co-60 and Cs-137. Moisture content of soil is 12%, pH of soil is 5.8, and content of organic matter is 2.2 %. Radioactive concentrations of the soil particle size of which is less than 0.063mm and soil in the drum surface of which is more than radiation dose rate 0.05mR/hr are higher. Meanwhile, radioactive concentration of soil in the drum surface of which is less than radiation dose rate 0.02 mR/hr are mostly lower. On using the mixing solution of ammonium sulfate and citric acid, 62% Co was removed from soil and 41% Cs was removed. Also, on using the mixing solution of ammonium nitrate and citric acid, 61% Co was removed from soil and 39% Cs was removed, and on using the mixing solution of ammonium potassium oxalate, 36% Co was removed and only 3% Cs was removed. And on using only water, removal efficiency is less than 5%.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 춘계 학술대회
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• pp.435-435
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• 2005

• 대한화학회지
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• 제4권1호
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• pp.38-43
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• 1957

Purified cellulosic materials suitable for the production of cellulose esters can be prepared from waste cotton (carding waste from textile mill). The most desirable conditions in purifying waste cotton were obtained. Waxy materials were removed by boiling in 2-3% soda ash solution for more than 30 minutes in open vessel at atmospheric pressure. As for bleaching, it is desirable to use the bleaching powder solution containing 1%, available chlorine for 60 minutes at 35 deg. C. Purified cellulosic material was acetylated to fibrous cellulose triacetate, which was fractionated in the solution of 70% monochloroacetic acid using water as a precipitant, and the degree of polymerizaion and molecular weight of each fraction were measured viscometrically, thereon, molecular weight distribution curve was drawn. Analyzing the shape of this curve, most of the polymers were concentrated on the part of higher degree of polymerization. Purified waste cotton was also analysed, the result was that this cellulosic material can be used as a raw material for cellulose esters and ethers.

• 청정기술
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• 제14권2호
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• pp.123-128
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• 2008

LCD 제조공정에서 배출되는 폐에칭액으로부터 조(粗)인산 회수 후 잔류하는 질산, 초산 혼산폐액을 분리하여 자원화함으로써 고부가가치화하고 2차 폐수의 발생이 없는 친환경적인 청정 재활용기술을 개발하고자 진공증발을 이용하여 혼산폐액을 분리하였다. 진공도 -760 mmHg 조건에서 온도의 따른 진공증발 결과 $33^{\circ}C$ 이하에서는 초산만 증발되었으나 $33^{\circ}C$ 이상에서는 초산과 함께 질산이 미량 증발되었다. 초산 회수율을 높이고 질산 증발을 억제하기 위하여 -760 mmHg, $40^{\circ}C$ 조건으로 증발시간에 따른 증발거동을 조사하고 회수되는 증발량을 고려하여 추가로 물과 원액을 공급하였다. 또한 질산만 선택적으로 반응하도록 20 g/L NaOH를 소량씩 단계적으로 공급하였다. 질산 증발은 batch type 에서는 7%이었으나, 물 추가 시 0.78%, 원액 추가 시 0.25%까지 감소하였다. 20 g/L NaOH를 소량씩 단계적으로 공급한 결과 초산 회수율은 100%까지 증가하였으며, 질산은 6.22%까지 증발하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제40권10호
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• pp.894-898
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• 2016

Solution plasma is a unique method which provides a direct discharge in solutions. It is one of the promising techniques for various applications including the synthesis of metallic/non-metallic nanomaterials, decomposition of organic compounds, and the removal of microorganism. In the context of nanomaterial syntheses, solution plasma has been utilized to produce carbon nanoparticles and metallic-carbon nanoparticle systems. The main purpose of this study was to synthesize nickel nanoparticles embedded in a matrix of carbon particles by solution plasma in one-step using waste vegetable oil as the carbon source. The experimental setup was done by simply connecting a bipolar pulsed power generator to nickel electrodes, which were submerged in the waste vegetable oil. Black powders of the nickel nanoparticles-embedded carbon (NiNPs/Carbon) particles were successfully obtained after discharging for 90 min. The morphology of the synthesized NiNPs/Carbon was investigated by a scanning electron microscope, which revealed a good dispersion of NiNPs in the carbon-particle matrix. The X-ray diffraction of NiNPs/Carbon clearly showed the co-existence of crystalline Ni nanostructures and amorphous carbon. The crystallite size of NiNPs (through the Ni (111) diffraction plane), as calculated by the Scherrer equation was found to be 64 nm. In addition, the catalytic activity of NiNPs/Carbon was evaluated by cyclic voltammetry in an acid solution. It was found that NiNPs/Carbon did not show a significant catalytic activity in the acid solution. Although this work might not be helpful in enhancing the activity of the fuel cell catalysts, it is expected to find application in other processes such as the CO conversion (by oxidation) and cyclization of organic compounds.