1992 Volume 18 Issue 6 Pages 904-910
Deashing of ultrafine coal slurries by selective flocculation was examined experimentally by using anionic polyacrylamides (polymer) with different hydrophobicities. As a result, (1) the agitation condition giving the optimum separation was clarified in terms of floc formation; (2) the addition of dispersant and pH adjustment of slurries were necessary for dispersion between coal and ash particles ; (3) with increasing hydrophobicity of the polymer the coal recovery increased, but the optimum dosage region of the polymer to maximize ash reduction became narrower; (4) the amount of the polymer adsorbed, and therefore the coal recovery, increased with increasing rank of the coal; (5) ash reduction was improved by washing with water to release the ash particles entrapped in the sediment enriched with carbonaceous matter.
