• Title/Summary/Keyword: Recovery of metal

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Dechlorination/Solidification of LiCl Waste by Using a Synthetic Inorganic Composite with Different Compositions (합성무기복합체 조성변화에 따른 모의 LiCl 염폐기물의 탈염소화/고형화)

  • Kim, Na-Young;Cho, In Hak;Park, Hwan-Seo;Ahn, Do-Hee
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.14 no.3
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    • pp.211-221
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    • 2016
  • Waste salt generated from a pyro-processing for the recovery of uranium and transuranic elements has high volatility at vitrification temperature and low compatibility in conventional waste glasses. For this reason, KAERI (Korea Atomic Energy Research Institute) suggested a new method to de-chlorinate waste salt by using an inorganic composite named SAP ($SiO_2-Al_2O_3-P_2O_5$). In this study, the de-chlorination behavior of waste salt and the microstructure of consolidated form were examined by adding $B_2O_3$ and $Fe_2O_3$ to the original SAP composition. De-chlorination behavior of metal chloride waste was slightly changed with given compositions, compared with that of original SAP. In the consolidated forms, the phase separation between Si-rich phase and P-rich phase decreases with the amount of $Al_2O_3$ or $B_2O_3$ as a connecting agent between Si and P-rich phase. The results of PCT (Product Consistency Test) indicated that the leach-resistance of consolidated forms out of reference composition was lowered, even though the leach-resistance was higher than that of EA (Environmental Assessment) glass. From these results, it could be inferred that the change in the content of Al or B in U-SAP affected the microstructure and leach-resistance of consolidated form. Further studies related with correlation between composition and characteristics of wasteform are required for a better understanding.

Characteristics and Fabrication of Micro Gas Sensor with Single Electrode (단일전극을 가진 마이크로 가스센서의 제작 및 특성)

  • Song, Kap-Duk;Bang, Yeung-Il;Lee, Sang-Mun;Lee, Yun-Su;Choi, Nak-Jin;Joo, Byung-Su;Seo, Moo-Gyo;Huh, Jeung-Soo;Lee, Duk-Dong
    • Journal of Sensor Science and Technology
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    • v.11 no.6
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    • pp.350-357
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    • 2002
  • Micro gas sensor with single electrode was proposed for improving stability and sensitivity. Generally, metal oxide gas sensors have two electrodes for heating and sensing. This fabricated new type sensor have only a single electrode by forming a sensing material onto heating electrode. Pt as a heating and sensing electrode was sputtered on glass substrate and a $SnO_2$ sensing material was thermally evaporated on Pt electrode. $SnO_2$ was patterned by lift-off process and then thermally oxidized in $O_2$ condition for 1 hr., $600^{\circ}C$. The size of fabricated sensor was $1.9{\times}2.1\;mm^2$. As a result of CO gas sensing characteristics, this sensor showed 100 mV change for 1,000 ppm and linearity for wide range($0{\sim}10,000\;ppm$) of gas concentrations. And the sensor shows a good recovery characteristics of 1% deviation compared to initial resistance.

Leaching Behavior of Heavy Metals from an Ore Containing High Concentration as Utilizing Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (Acidithiobacillus ferrooxidans와 Acidithiobacillus thiooxidans를 활용한 고농도 비소 함유 광석 내 중금속 용출 거동 연구)

  • Kim, Gahee;Kim, Rina;Kim, Kwanho;You, Kwang-suk
    • Resources Recycling
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    • v.30 no.2
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    • pp.14-23
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    • 2021
  • To investigate the potential for leaching of heavy metals by bacteria from ores stacked on actual mining sites, leaching tests of a complex metallic ore (Pb-Zn-As ore) were conducted over 60 days using acidophile bacteria Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans under initial acidic conditions. Initially, a small amount of heavy metals was leached due to the initial acidic conditions. After 20 days, when A. thiooxidans in the reactor was adapted to the ore, the amount of leached heavy metals rapidly increased; the concentrations of leached arsenic, iron, and zinc reached a maximum of 2800, 3700, and 2500 mg/L, respectively. On the other hand, in the presence of A. ferrooxidans or in the control test without bacteria, heavy metals, except zinc, were barely detected in leaching. Through this study, it was confirmed that (i) bacteria could leach heavy metals at mining sites under acidic conditions and (ii) leaching of heavy metals from a high arsenic-containing ore by A. thiooxidans was more significant than that by A. ferrooxidans.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

Biosorption and Development of Biosorbent by using Seaweed, Sugassum thunbergii (해조류, Sargassum thunbergii를 이용한 중금속의 바이오 흡착제의 개발)

  • SUH Kuen-Hack;LEE Hak-Sung;SUH Jung-Ho
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.33 no.1
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    • pp.60-65
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    • 2000
  • Biosorptions of Cr and Pb were evaluated for 23 species of marine algae collected from a Korean coast. Among a variety of species for biosorbent potential, Sargassum species showed higher uptake capacity for Cr and Pb. An adsorption equilibrium was reached in about 1 hr for Cr and 30 min for Pb. The maximum uptake capacity was136.0 mg Cr/g biomass and 232.5 mg Pb/g biomass, respectively. In Pb biosorption in the column packed with Sargassum tbunbertii, 300 and 200 bed Tolumes at the concentration of 50 mg/L in feed solution were processed at the column residence time of 5 and 10 min before the column breakthrough point occurred. The elutions with 0.1 M HCl solution were more than $95{\%}$. The high efficiency of continous biesorntion and elution (3 cycles) indicated that Sargassum thunbergii was an effective biosorbent for Pb recovery.

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Separation of chlorine in a uranium compound by pyrohydrolysis and steam distillation, and its determination by ion chromatography (열가수분해 및 수증기증류에 의한 우라늄 화합물 중 염소 분리 및 이온크로마토그래피 정량)

  • Kim, Jung-Suk;Lee, Chang-Hun;Park, Soon-Dal;Han, Sun-Ho;Song, Kyu-Seok
    • Analytical Science and Technology
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    • v.23 no.1
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    • pp.45-53
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    • 2010
  • For the determination of chlorine in uranium compound, analytical methods by using a steam distillation and a pyrohydrolysis have been developed. The steam distillation apparatus was composed of steam generator, distilling flask and condenser etc. The samples were prepared with an aliquot of LiCl standard solution and a simulated spent nuclear fuel. A sample aliquot was mixed with a solution containing 0.2 M ferrous ammonium sulfate-0.5 M sulfamic acid 3 mL, phosphoric acid 6 mL and sulfuric acid 15 mL. The chloride was then distilled by steam at the temperature of $140^{\circ}C$ until a volume of $90{\pm}5\;mL$ is collected. The pyrohydrolysis equipment was composed of air introduction system, water supply, quartz reaction tube, combustion tube furnace, combustion boat and absorption vessel. The chloride was separated from powdered sample which is added with $U_3O_8$ accelerator, by pyrohydrolysis at the temperature of $950^{\circ}C$ for 1 hour in a quartz tube with a stream of air of 1 mL/min supplied from the water reservoir at $80^{\circ}C$. The chlorides collected in each absorption solution by two methods was diluted to 100 mL and measured with ion chromatography to determine the recovery yield. For the ion chromatographic determination of chlorine in molten salt retained in a metal ingot, the chlorine was separated by means of pyrohydrolysis after air and dry oxidation, and grinding for the sample.

A Study on Microstructure and Mechanical Properties of Modified 9Cr-1Mo and 9Cr-0.5Mo-2W Steels for nuclear Power Plant (원자력용 개량 9Cr-1Mo 및 9Cr-0.5Mo-2W 강의 미세조직과 기계적 특성 연구)

  • Kim, Seong-Ho;Song, Byeong-Jun;Han, Chang-Seok;Guk, Il-Hyeon;Ryu, U-Seok
    • Korean Journal of Materials Research
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    • v.9 no.11
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    • pp.1137-1143
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    • 1999
  • Microstructure and mechanical properties of Mod.9Cr-1Mo and W added 9Cr-0.5Mo2W steels were investigated for liquid metal reactor (LMR) heat exchange tube. The tempering temperatures at which cell structure was formed were $700^{\circ}C$ for Mod.9Cr-1Mo steel and $750^{\circ}C$ for W added 9Cr0.5Mo-2W steel. indicating the recovery of dislocation was delayed by the addition of W. 9Cr-0.5Mo-2W steel had the same kinds of precipitates with Mod.9Cr-1Mo steel, but the W was included in the precipitates in 9Cr-0.5Mo-2W steel. Micro-hardness and ultimate tensile strength of 9Cr-0.5Mo-2W steel were higher than those of Mod.9Cr-1Mo steel. The impact property of Mod.9Cr-1Mo steel was superior to that of 9Cr-0.5Mo-2W steel.

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Development of Rapid Analytical Method for Heavy Metals (Cd, Pb) in Meju using fs LA-ICP-MS (fs LA-ICP-MS를 이용한 메주의 유해중금속(Cd, Pb) 신속 분석법 개발)

  • Shin, Hee-Chang;Choi, Ji-Hye;Kim, Yong-Kyoung;Kim, Dae-Jung;An, Jae-Min;Kim, Sung-Youn
    • Journal of Food Hygiene and Safety
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    • v.37 no.3
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    • pp.129-135
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    • 2022
  • The official analytical method for the analysis of harmful heavy metals in Meju, distributed in Korea, employs a strong acid to decompose the organic components. This analysis is time consuming and harmful to the users and/or the environment. This study aimed to develop a new pre-treatment technology using laser ablation, to rapidly analyze harmful heavy metals without using strong acids. The results obtained from this method were validated by the National Institute of Food and Drug Safety Evaluation guideline (NIFDS, 2016). Moreover, a comparison of the two methods showed that the analytical time for 55 Meju samples was shortened by 96% or more in the new method. The results showed no significant difference in the recovery ranging from 90-120%. The proposed method proved suitable for detecting harmful heavy metals in Meju.

The Evaluation of Cerebral Executive Function Using Functional MRI (기능적 자기공명영상기법을 이용한 대뇌의 집행기능 평가)

  • Eun, Sung Jong;Gook, Jin Seon;Kim, Jeong Jae
    • Journal of the Korean Society of Radiology
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    • v.7 no.5
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    • pp.305-311
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    • 2013
  • This study involves an experiment using functional magnetic resonance imaging(fMRI) to delineate brain activation for execution functional performance. Participates to this experiment of the normal adult (man 4, woman 6) of 10 people, is not inserts the metal all closed phobia and 24.5 year-old average ages which the operating surgeon experience which are not they were. The subject for a functional MRI experiment word -color test prosecuting attorney subject rightly at magnetic pole presentation time of 30 first editions and after presenting, uses SPM 99 programs and the image realignment, after executing a standardization (nomalization), a difference which the signal burglar considers the timely order as lattice does, pixel each image will count there probably is, in order to examine rest and active crossroad dividing independence sample t-test (p<.05). Overlapped in this standard anatomic image and got a brain activation image from level of significance 95%. With functional MRI resultant execution function inside being relation, the prefrontal lobe, anterior cingulate gyrus, parietal lobe, orbitofrontal gyrus, temporal lobe, parietal lobe was activated. The execution function promotes a recovery major role from occupational therapy, understanding about the damage mechanism is important. When confirms the brain active area which accomplishes an execution function brain plasticity develops the cognitive therapeutic method which is effective increases usefully very, will be used.

Effect of Rare Earth Elements on Uranium Electrodeposition in LiCl-KCl Eutectic Salt (LiCl-KCl 공융염에서 우라늄 전착거동에 대한 희토류 원소들의 영향)

  • Park, Sungbin;Kang, Young-Ho;Hwang, Sung Chan;Lee, Hansoo;Paek, Seungwoo;Ahn, Do-Hee
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.13 no.4
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    • pp.263-269
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    • 2015
  • It is necessary to investigate the electrodeposition behavior of uranium and other elements on the cathode in the electrorefining process to recover the uranium selectively from the reduced metals of the electrolytic reduction process since transuranic elements and rare earth elements is dissolved in the LiCl-KCl eutectic salt. Study on separation factors of U, Ce, Y and Nd based on U and Ce was performed to investigate the deposition behavior of the cathode with respect to the concentration of rare earth elements in LiCl-KCl eutectic salt. After electrorefining with constant current mode by using Ce metal as a sacrifice anode, the contents of U, Ce, Y and Nd in the salt phase and the deposit phase of the cathode were analyzed, and separation factors of the elements were obtained from the analyses. Securing conditions of pure uranium recovery in the elctrorefining process was investigated by considering the separation factors with respect to $UCl_3$ and $CeCl_3/UCl_3$ ratio.