Effect of electrolytes on the flotation of copper minerals in the presence of clay minerals

• Kaolinite coating can occur on chalcocite surfaces depressing chalcocite flotation.
• Electrolytes mitigate kaolinite coating on chalcocite surfaces.
• Anions and cations with a greater atomic size have a more beneficial effect.

Clay minerals have a deleterious effect on flotation. In a previous study (Peng and Zhao, 2011), the authors found that the flotation of secondary copper minerals such as chalcocite was more affected by clay minerals than the flotation of primary copper minerals such as chalcopyrite due to stronger surface oxidation resulting in an electrostatic attraction to clay particles. In this current study, the intention was to use electrolytes to mitigate the adverse effect of clay minerals on chalcocite flotation. A copper ore mainly containing chalcocite was examined. In fresh tap water, kaolinite significantly depressed chalcocite flotation. However, with an increase in the electrolyte concentration, the recovery of chalcocite was increased. It is concluded that the electrolytes reduce the electrostatic attraction between kaolinite and chalcocite so that the surface coating of kaolinite on chalcocite surfaces may be mitigated leading to improved chalcocite flotation. It is interesting to find that anions and cations with a greater atomic size had a more beneficial effect which may be associated with their tendency to modify surface hydrophobicity.