The effect of surface oxidation of copper sulfide minerals on clay slime coating in flotation

The industry is well aware of the difficulty in treating copper ores in the presence of clay minerals. In this study, the effect of bentonite on the flotation of chalcopyrite (a primary copper sulfide mineral) and chalcocite (a secondary copper sulfide mineral) was investigated in terms of surface coating. Based on the flotation of copper ores containing both chalcopyrite and chalcocite, the flotation of chalcopyrite and chalcocite single minerals in the presence and absence of bentonite, and the zeta potential measurement of chalcopyrite, chalcocite and bentonite, it was found that the oxidation of chalcopyrite and chalcocite had a different effect on their interaction with bentonite. Under the normal grinding and flotation condition, significant oxidation occurred on the surface of chalcocite which was electrostatically attractive to bentonite resulting in bentonite slime coating and the depressed flotation of chalcocite. The reduction of oxidation on chalcocite could mitigate bentonite slime coating due to electrostatic repulsion between unoxidized chalcocite and bentonite. Unlike chalcocite, chalcopyrite with and without surface oxidation exhibited an electrostatic repulsion to bentonite. Its flotation was less affected by bentonite slimes.

The oxidation of chalcopyrite and chalcocite under the normal grinding and flotation condition alters the electrical properties on the surfaces and their interaction with bentonite slimes.Figure optionsDownload as PowerPoint slideHighlights
► The flotation of chalcocite is more affected by bentonite than the flotation of chalcopyrite.
► Chalcocite is more oxidized than chalcopyrite under the normal grinding and flotation condition.
► An electrostatic attraction between the oxidized chalcocite and bentonite promotes the slime coating.
► Bentonite has less effect on the flotation of chalcopyrite with and without strong oxidation.