Method for separating fine particles by selective hydrophobic coagulation

A process of selectively agglomerating coal in an aqueous environment while leaving the mineral matter dispersed has been developed. This process is autogenous for hydrophobic particles in that neither an agglomerating agent nor an electrolytic coagulant is needed. It is based on the finding that hydrophobic particles are pushed against each other by the surrounding water structure. This process, which is referred to as selective hydrophobic coagulation, is driven by the so-called hydrophobic interaction energy, which is not included in the classical DLVO theory describing the stability of lyophobic suspensions. The relatively small coagula formed by the selective hydrophobic coagulation process can be readily separated from the dispersed mineral matter by several different techniques such as screening, elutriation, sedimentation and froth flotation.