Recovery of fine coal from waste streams by the selective flocculation process

Abstract

In the United States, a significant amount of fine, −150-μn (−100-mesh) coal is rejected because of the unavailability of an economical recovery process. In the last decade, coal companies have realized the financial and environmental potential for recovering the fine clean coal from waste streams. Selective flocculation, which has been successfully applied in the iron mining industry, has the potential for recovering this fine coal. The main objective of the present program is to investigate the applicability of selective flocculation for recovering clean coal from waste stream samples obtained from a coal preparation plant owned by the Peabody Coal Co. The results of the study showed that I kg/t (2 lb/st) dispersant and 2 g/t flocculant was effective in recovering a clean coal product containing 14% ash with a 90% combustible recovery. Three-stage cleaning of the flocculated coal provided a 10%-ash clean coal. The study also found that a Hydrofloat Separator is effective in separating the flocculated coal from the dispersed ash material on a continuous basis. With the Hydrofloat separator, a clean coal containing 14% ash was obtained with a 90% combustible recovery.