Selective Aggregation of Hydrophilic Gangue Minerals in Froth Flotation

Abstract

In a highly dispersed flotation pulp, ultrafine hydrophilic minerals can entrain into froth products even though they may be perfectly hydrophilic. Therefore, effective depression of the hydrophilic minerals in froth flotation relies not only on rendering the minerals hydrophilic, but also on proper particle size control. In this paper, it will be shown that several depressants in mineral flotation systems indeed not only make the minerals hydrophilic but also cause selective coagulation or flocculation of the hydrophilic minerals. As a result, both the genuine flotation and the hydraulic entrainment of the hydrophilic minerals are reduced. The aforementioned depressants and mineral flotation systems include: zinc sulfate in the depression of sphalerite while copper sulfide and lead sulfide are floated; starch in the depression of iron oxides and phosphates while quartz is floated; polyethylene oxide in the depression of quartz while sulfide minerals such as chalcopyrite is floated. Therefore, in fine and ultrafine particle flotation, the flotation depressants should be able to not only make the to-be-depressed minerals hydrophilic, but also make them selectively aggregate.