Kim DS  Han GS  Lee DK

Vol. 25,  No. 3, pp. 179-188, Sep.  2019
10.7464/ksct.2019.25.3.179

Coal ash Fly ash wet flotation separation unburned carbon

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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 4,232 kcal 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 SiO2 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.