Sphalerite activation: Flotation and electrokinetic studies

Abstract

Sphalerite is commonly floated in an alkaline environment and under such conditions the overall activation mechanism is obscured by the hydrolysis of Cu 2+ and precipitation of Cu(OH) 2. Electrokinetic and kinetic flotation tests showed that the activation of sphalerite is a two-stage process; the activation products formed on the surface of sphalerite in near neutral and in alkaline solutions in the first rapid activation stage are “flotation-inactive”. These layers, when formed in an alkaline solution, are unstable and are transformed into the “flotation-active” form in the second stage. However, the surface layers formed during activation in alkaline environment by copper in the presence of lead ions are very stable and even after a long conditioning time the flotation rate is not improved. Consequently, while both Cu 2+ and Pb 2+ activate sphalerite flotation, quite unpredictable effects may result when both are present in the solution.