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 gives best
recoveries, and finding the effect of the chrome content in these
recoveries. A pH of 9 gave the highest recovery compared to
other pH ranges. 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.