A review of pyrrhotite flotation chemistry in the processing of PGM ores

Thermodynamically pyrrhotite is not stable and reacts relatively quickly with its environment. Natural/collectorless flotation of pyrrhotite is observed only under a low oxidation potential in acidic solution. Its surface is easily oxidized to ferric hydroxide/oxide under conventional flotation conditions, creating a hydrophilic state at the pyrrhotite surface and low flotation recovery even though xanthate collectors can be adsorbed. Under these conditions, activation by copper is not easily achieved. These observations reported in the literature have been confirmed by captive bubble contact angle measurements. Based on the analysis of previous research, conditions for improved pyrrhotite flotation and increased PGM recovery are suggested.