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Recycling of useful Materials from Fly Ash of Coal-fired Power Plant

석탄화력발전소에서 발생되는 비회로부터 유용성분의 회수

  • Kim, Dul-Sun (Department of Chemical Engineering, Gyeongsang National University) ;
  • Han, Gwang Su (Department of Environment Protection, Gyeongsang National University) ;
  • Lee, Dong-Keun (Department of Chemical Engineering, Gyeongsang National University)
  • 김둘선 (경상대학교 화학공학과) ;
  • 한광수 (경상대학교 환경보전학과) ;
  • 이동근 (경상대학교 화학공학과)
  • Received : 2019.08.12
  • Accepted : 2019.09.01
  • Published : 2019.09.30

Abstract

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.

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