Decoupling the effects of alteration on the mineralogy and flotation performance of Great Dyke PGE ores

Raw data from: Dzingai, T., McFadzean, B., Tadie, M. & Becker, M. 2021. Decoupling the effects of alteration on the mineralogy and flotation performance of Great Dyke PGE ores.

Abstract: Ores from the same deposit may exhibit extensive variability in their mineralogy and texture. The ability to quantify this variability while linking it to minerals processing performance is one of the primary goals of process mineralogy. This study focuses on the effect of alteration as a source of ore variability in three Great Dyke platinum group element ore samples from Zimbabwe – two of which were more pristine compared to the third that was locally classified as ‘oxidised’ ore. These ores are known to be characterized by varying degrees of alteration resulting in numerous challenges in flotation affecting both grade and recovery. Alteration via near surface oxidation of the valuable base metal sulfides and platinum group minerals resulted in lower flotation recoveries of Cu, Ni, Pt, Pd. Evidence of incipient oxidation was more readily observed in the base metal sulfide assemblage than the platinum group mineral assemblage, even though the loss in recovery because of oxidation was most significant for Pd. The effect of the alteration through hydration resulted in a significant increase in mass pull and dilution of concentrate grade through the inadvertent recovery of naturally floating gangue comprising composite orthopyroxene and talc particles. In this study, the amount of naturally floating gangue was more strongly correlated with the talc grain size distribution than the grade of talc in the flotation feed. These oxidation and hydration alteration reactions are not necessarily mutually exclusive although one may be more dominant than the other giving rise to ore variability.