Extracting unburnt coal from black coal fly ash

Black-coal fly ash from Kosice Power Plant in Slovakia contains between 22 and 25% of unburnt coal, which is, strictly speaking, a useful component. Studying optimal separation methods of unburnt coal from the examined sample of fly ash, three methods of dry mechanical screening on sieves, counterflow air classification, dry and wet gravity separation and flotation have been verified. The combination of dry mechanical screening and flotation appears to be the most efficient, through the application of which we retrieved coal concentrate with ash content below 10%, which is applicable in the process of power generation in power plants.