Influence of galvanic interaction between chalcopyrite and some metallic materials on flotation

Galvanic interactions between the grinding media and the ground mineral inside a ball mill could not only accelerate the media wear but also adversely affect the flotation response of the ground mineral. Rest potential, combination potential and galvanic current measurements were carried out to understand the probable electrochemical interactions between chalcopyrite and several metallic electrodes such as platinum, stainless steel, hyper steel, mild steel and cast iron. Flotation recovery of chalcopyrite was found to be significantly lowered when contacted with hyper steel, mild steel or cast iron prior to flotation unlike with platinum or stainless steel. The influence of the presence of collector during galvanic interaction as well as the effect of relaxation for fresh and galvanically interacted chalcopyrite samples were also studied with respect to its floatability. AES and ESCA analyses indicated that galvanic coupling of chalcopyrite with a hyper steel grinding medium resulted in the formation of hydroxide or oxide species of iron on the mineral surface. An electrochemical mechanism is proposed to explain the mineral-grinding media interaction and its effect on flotation.