Effect of pH on the floatability of base metal sulphides PGMs

Abstract

This study investigated the effect of pH on the recovery and grade of the Platinum Group Metals (PGMs) and base metal sulphides from the UG2 ore of the bushveld complex. This was achieved through running a series of test work in a Denver flotation cell at varying pH 6-11 at constant reagent dosage. The UG-2 reef is characterized by two predominant gangue phases i.e., chromite and silicate, that have significantly different physical and chemical properties. The test work was aimed at evaluating which pH produces the best recoveries, and finding the effect of the chrome content in these recoveries. A pH of 9 produced the highest recovery compared to other pH values. However, the highest PGM grade was attained at a pH of 6 which is slightly acidic. Ideally this trend could be expected since the collectors (xanthates) are more stable in alkaline medium. The higher PGM recovery was also accompanied by higher chrome content as a result of their similar chemical properties. © 2013 Springer Science+Business Media.