Investigations into the Recovery of Platinum Group Minerals from the Platreef Ore of the Bushveld Complex of South Africa

In the flotation of platinum group minerals (PGMs) it has generally been assumed that they will behave similarly to base metal sulfides and thus sulfide reagent regimes are generally used in such flotation plants. However the tellurides and arsenides of platinum and palladium contribute about 50% of the PGMs present in the Platreef ore, located in the northern limb of the Bushveld Complex of South Africa, and there is evidence of these minerals reporting to the flotation tailings. The present investigation was aimed at studying the flotation behaviour of tellurides, arsenides and sulfides of Pt and Pd and relating these observations to their surface characteristics. Microflotation, zeta potential determinations, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) analyses were used to study the synthesised samples after various treatments. It was shown that in almost all cases the addition of a typical sulfide collector, sodium isobutyl xanthate (SIBX), increased the recovery of all the Pt and Pd minerals investigated but that the presence of copper sulfate widely used to activate sulfide minerals caused the recoveries to decrease. These results may question the value of adding copper sulfate in the treatment of Platreef PGM-bearing ore.