• Title, Summary, Keyword: CaO회수

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Recovery of An, Ag, and Ni from PCB Wastes by CaF2-containing Slag (형우(螢右) 함유(含有) 슬래그 노이(盧理)를 통한 PCB 스크랩으로부터 Au, Ag, Ni의 회수(回收)에 관한 연구(班究))

  • Park, Joo-Hyun
    • Resources Recycling
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    • v.20 no.4
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    • pp.58-64
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    • 2011
  • Recovery of novel metals such as Au, Ag and Ni from wastes PCB was investigated by slag treatments. The CaO-$Al_2O_3$(-$SiO_2$) and CaO-$SiO_2$-$CaF_2$ slags were employed in the present study. The PCB/Cu ratio is recommended to be lower than unity. The use of CaO-$SiO_2$-$CaF_2$ slag provided the more higher yield of Au, Ag and Ni than the CaO-$Al_2O_3$(-$SiO_2$) slag did, which was mainly due to the lower melting point and the viscosity of $CaF_2$-containing slag. The terminal descending velocity of metal droplets in the slag phase increased with decreasing slag viscosity.

Utilization of Ready-mixed Concrete Recycling Water Mixed with Hot-rolled Slag Containing C12A7 and Application Characteristics of Cement Mortar (C12A7을 함유한 열연슬래그를 혼입한 레미콘 회수수 활용 및 시멘트 모르타르의 적용 특성)

  • Kim, Young-Yeop;Lee, Han-Seung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.1
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    • pp.92-99
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    • 2021
  • CaO-based by-products composed of CaO, SO3, Al2O3, etc. are generally used as raw materials for CaO compounds. When applied to the recovered water of ready-mixed concrete, the hydration reaction of the powder material is accelerated and concrete performance can be improved. In this study, activated sludge was prepared to apply to the recovered water of ready-mixed concrete by mixing CaO-based hot-rolled slag(C12A7) in the recycling water of ready-m ixed concrete. Cem ent paste setting time and mortar compressive strength performance tests confirmed the effect on the hydration reaction. Therefore, the possibility of concrete application using activated sludge was confirmed.

Development of Technology for Recovering Valuable Metals in Detoxified Waste Asbestos-Containing Waste (무해화된 폐석면에 함유된 유가금속 회수 기술 개발)

  • Kim, Dong Nyeon;Yang, Dong Hyeon;Kim, Seok Chan
    • Applied Chemistry for Engineering
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    • v.31 no.4
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    • pp.438-442
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    • 2020
  • Studies on the recovery conditions and optimization process for valuable metal recovery through chemical treatment from detoxified asbestos-containing waste composed of calcium silicate, larnite, merwinite, and akermanite were conducted. The main components, Si, Ca, and Mg, of detoxified asbestos-containing waste (DACW) were separated and recovered in the form of SiO2, CaSO4, and Mg(OH)2 compounds, respectively. Each separated component was confirmed through X-ray diffraction (XRD) and inductively coupled plasma spectrometer (ICP) analysis. The recovery conditions for each component were first treating them with an acid to separate SiO2 and subsequently with H2SO4 to recover Ca in the form of sulfate, CaSO4. The remaining Mg was recovered by precipitation with Mg(OH)2 under strong basic conditions. This study suggested that it is possible to convert existing treatment process of asbestos waste by landfill through recovering the components into a resource-recycling green technology.

Characteristics of Concrete Using Ready-Mixed Concrete Recycled Water Mixed with Industrial By-Product Desulfurization Gypsum (산업부산물 탈황석고 혼입 레디믹스트콘크리트 회수수를 이용한 콘크리트의 특성)

  • Kim, Young-Yeop;Lee, Han-Seung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.4
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    • pp.395-403
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    • 2020
  • CaO-based by-product, which consist of CaO, SO3, Al2O3 and so on, has being used to raw materials of CaO compound. When It was applied to recycling water of remicon, concrete performance can be enhanced because hydration reaction of powder material is accelerated. In this study, activated-sludge, which was putted desulfurization gypsum of CaO-based in recycling water, was manufactured to verify effect of them, and then they was investigated by characteristics of redy-mixde concrete. As a result of concrete tests, it was confirmed that there is no problem of strength or drying shrinkage while ensuring workability. Therefore, the possibility of specific application using activated sludge was confirmed.

Study on $CaCO_3$ Preparation from MSWI Fly Ash (생활쓰레기 소각(燒却)비산재로부터 $CaCO_3$ 제조(製造)에 관한 연구(硏究))

  • Choi, Woo-Zin;Park, Eun-Kyu
    • Resources Recycling
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    • v.15 no.5
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    • pp.47-51
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    • 2006
  • The total amount of ash generated from the municipal solid waste incineration(MSWI) in Korea was approximately 420,000 tons in 2005 including 68,000 tons of fly ash. Fly ash from MSWI generally contains high amount of CaO (upto ${\sim}50%$) due to the treatment of flue gas by spraying CaO-base materials. Currently, most of fly ash generated is finally ended up with specially designed landfill sites and only less then 20% of fly ash is recycled. In the present work, preparation of $CaCO_3$ from the MSWI ny ash was studied to promote the fly ash recycling. Fly ash obtained from the dust collector in stoker-type MSWI is used to selectively dissolve CaO by using the sugar solution. Then, $CO_2$ gas was passed through the dissolved solution to pro- duce $CaCO_3$ powder. The optimum conditions for CaO dissolution were solid content 10%, reaction time 15 minutes, sugar concentration $10{\sim}15%\;and\;pH\;10.5{\sim}11.0$. The high grade $CaCO_3$ powder was obtained and the experimental conditions are also discussed.

Recovery and Characterization of Lactic Acid from Fermentation Broth Using Chemical Precipitation (화학침전을 이용한 발효액의 젖산 회수 및 유기물 특성분석)

  • Lee, Wontae
    • Journal of the Korea Organic Resources Recycling Association
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    • v.26 no.1
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    • pp.47-53
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    • 2018
  • Recovery of lactic acid from fermentation broth using chemical precipitation was investigated with various chemicals. Effects of chemical types, mixing speeds, settling duration, and solvent addition were evaluated to improve the recovery rates of lactic acid. Overall, recovery efficiencies increased as the dosage of chemicals increased. Recovery rate of lactic acid by CaO was higher than those of $Ca(OH)_2$ and $CaCO_3$. Recovery of lactic acid increased by 48% under the optimized reaction conditions which included a mixing speed at 180 rpm, a settling duration of 24 h, and addition of ethanol at 25%(v/v). Practical application needs to consider types and concentrations of other organic acids as well as lactic acid. Based upon the results of fluorescence excitation emission matrix (FEEM), size exclusion chromatography (SEC), characteristics of recovered lactic acid were same as that in the fermentation broth.

Optimization of Precipitation Process for the Recovery of Lactic Acid (Lactic acid 회수를 위한 침전공정 최적화)

  • Choi, Kook-Hwa;Chang, Yong-Keun;Kim, Jin-Hyun
    • KSBB Journal
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    • v.26 no.1
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    • pp.13-18
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    • 2011
  • In this study, precipitation process was developed for the recovery of the lactic acid from calcium lactate fermentation broth. Calcium lactate yield was improved by decreasing the solubility of calcium lactate through the addition of ethanol (25%, v/v) as a co-precipitant. The optimal lime type, lime concentration, stirrer speed, precipitation time, temperature, and solvent amount for $Ca(LA)_2$ precipitation were CaO, 0.0175 g/mL, 220 rpm, 24 h, $5^{\circ}C$, ethanol 25% (v/v), respectively. Lactic acid was easily and efficiently recovered from precipitated $Ca(LA)_2$ by adding sulfuric acid ($Ca(LA)_2/H_2SO_4$ molar ratio=1:1). In the model solution of organic acids and fermentation broth, the overall yields of recovered lactic acid were 62% and 55%, respectively, under the aforementioned optimal conditions.

A Study on the Recovery of a Metalic Fe-particle from the Steelmaking E.A.F. Slag by the Magnetic Separation (전기로 제강 슬래그에서 자력선별에 의한 지금의 회수)

  • 현종영;김형석;신강호;조동성
    • Resources Recycling
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    • v.6 no.3
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    • pp.3-8
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    • 1997
  • The EA.F. sleelmaking slag (slag that follow) of a cnmvany 1 Co.. containzd a simple substance of a metal, wustlte (FeO), magnetite (Fe,O,), gehlenite (CaAl,SiO,), monlicellite (CaMgSiO,), dc. To recovere a metal (Fe grade . t95%) in the slag, it is desirable that the particles of a metal are isolated from thc slag and madc for a liberated subslance. Then, the liberaled melal is easlly recoveled by a magnetic separation. If thc rcclarnalcd slag, the sizc of which ranges under 40 nun, have a mulli-stage crushing, the most of a metal in thc slag is simply isolaled as a liberated subslance. If the mad, lhat is a liberated subslance and a sphere, is recovered by a magnetic field intensity. the minimum intensity, at which a metal is attracted, is approximately IOOG and did no1 dcpcnd on the particle size of a metad in the same particles. TIe recovered material. that contdined a iron (Fe) over 95% is a metal which is crushed slag by l00G in the multi-stage. If the magnetic field intcns~ty increase, the recovery mcrcasc, but the concentration grade decrease Bewusc thc concentration eams more and more impurities, iron oxide and the coml~ound of alkali earth element. 'll~ercforc If the rccla~nated slag have the multi-stage crushing, the metal is almostly recovered in the crushed slag by lO0G on each particles. If the slag, used as a rcclamatian lhat is a amount of 350,000 tan from I Co., was undcr the multistage crushing and then separaled by 100gauss, it is possible to recova a metal approximately 2.500 Ion, lhat is 0.73% of n ~eclamated slag. in 304.7 mm particles and to recover 4.200 tan in 0.3-1.7 mm particles , that is 1.2% nf a rcclamated slag, in a year. Therefore, ihe told recoverable meld is 6,700 ton, that is 19% of a reclmated slag, in a year, too.

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Characteristics of Cement Matrix/Mortar with CaO-based Activated-sludge (CaO원 활성슬러지를 혼입한 시멘트 경화체 및 모르타르의 특성)

  • Lee, Yong-Soo;Ryu, Seong-Lyong;Shin, Kwang-Ho;Chu, Yong-Sik;Kim, Young-Yup
    • Journal of the Korea Concrete Institute
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    • v.29 no.4
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    • pp.399-406
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    • 2017
  • CaO-based by-product, which consist of CaO, $SO_3$, $Al_2O_3$ and so on, has being used to raw materials of CaO compound. When It was applied to recycling water of remicon, concrete performance can be enhanced because hydration reaction of powder material is accelerated. In this study, activated-sludge, which was putted desulfurization gypsum of CaO-based in recycling water, was manufactured to verify effect of them, and then they was investigated by characteristics of cement matrix and mortar. As a results, they indicated reduction of setting time and high soundness in cement matrix, and acceleration of hydration reaction can be verified by XRD analysis. Also, it can be maintained good workability if water content by usage of desulfurization gypsum, which used for production of activated-sludge, was adjusted. In addition, it can be verified strength development by activated-sludge although cement content by usage of desulfurization gypsum was reduced.

Recycling of useful Materials from Fly Ash of Coal-fired Power Plant (석탄화력발전소에서 발생되는 비회로부터 유용성분의 회수)

  • Kim, Dul-Sun;Han, Gwang Su;Lee, Dong-Keun
    • Clean Technology
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    • v.25 no.3
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    • pp.179-188
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    • 2019
  • Upon the combustion of coal particles in a coal-fired power plant, fly ash (80%) and bottom ash (20%) are unavoidably produced. Most of the ashes are, however, just dumped onto a landfill site. When the landfill site that takes the fly ash and bottom ash is saturated, further operation of the coal-fired power plant might be discontinued unless a new alternative landfill site is prepared. In this study, wet flotation separation system (floating process) was employed in order to recover unburned carbon (UC), ceramic microsphere (CM) and cleaned ash (CA), all of which serving as useful components within fly ash. The average recovered fractions of UC, CM, and CA from fly ash were 92.10, 75.75, and 69.71, respectively, while the recovered fractions of UC were higher than those of CM and CA by 16% and 22%, respectively. The combustible component (CC) within the recovered UC possessed a weight percentage as high as 52.54wt%, whereas the burning heat of UC was estimated to be $4,232kcal\;kg^{-1}$. As more carbon-containing UC is recovered from fly ash, UC is expected to be used successfully as an industrial fuel. Owing to the effects of pH, more efficient chemical separations of CM and CA, rather than UC, were obtained. The average $SiO_2$ contents within the separated CM and CA had a value of 53.55wt% and 78.66wt%, respectively, which is indicative of their plausible future application as industrial materials in many fields.