Selective flocculation of coal

摘要

A method for separating inorganic gangues from coal particulates dispersed in a coal refuse slurry comprises the selective flocculation of the coal refuse slurry by initially adding an anionic dispersant followed subsequently by adding an anionic flocculant, allowing the flocculating coal slurry obtained to settle and collecting a concentrated settled coal slurry having a lowered ash value. The dispersed inorganic gangues may be recovered by the addition of a cationic flocculant/coagulant with subsequent recycle of the aqueous phase.