Surface characteristics and flotation behaviour of platinum and palladium tellurides

The telluride minerals, moncheite ((Pt,Pd)(Bi,Te)2 and PtTe2) and merenskyite ((Pd,Pt)(Bi,Te)2 and PdTe2), contribute between 20% and 45% of the PGMs present in the Platreef ore which is located in the northern limb of the Bushveld Complex of South Africa. There is evidence of these minerals reporting to the tailings and the present investigation was aimed at determining their flotation behaviour and to relate this to their surface characteristics.Microflotation, zeta potential determinations, ToF-SIMS analyses (time of flight-secondary ion mass spectrometry) and X-ray photoelectron spectroscopy (XPS) were used to characterise the flotation and surface behaviour of the synthesised samples. Copper activation of both moncheite and merenskyite samples reduced the flotation response compared with xanthate on its own. When xanthate is added on its own, it is adsorbed on the mineral surfaces at a higher concentration compared to the copper activated minerals.Oxidation of the PGE telluride minerals negatively affects the flotation performance of the Pt and Pd bismuth telluride samples respectively but not the Pt and Pd telluride samples. Grinding finer reduced recoveries and increasing the calcium ion concentration from 80 ppm to 500 ppm in the synthetic water did not negatively affect the flotation response of the PdTe2 mineral.