The Enhancement of Galena Flotation Using Cyanide

In an on-going study of the chemistry of base metal sulphide flotation, the effect of the inclusion of cyanide in the reagents suite has been studied, with special reference to ore from Pasminco Mining's Elura mine. Cyanide has been variously described as an iron sulphide depressant, a preventor of sphalerite activation and as an activator of galena. In the case described here, the cyanide appeared to act as an enhancer of the galena flotation performance, raising the lead recoveries by 25 per cent but leaving the sphalerite and pyrite responses unaffected. The lead rougher flotation performance with and without cyanide was investigated over a wide range of redox potentials (0 mV to 400 mV SHE). In all cases, the inclusion of the cyanide brought about an increase in the galena recovery and was responsible for a faster rate of galena flotation during the initial stages of the beneficiation. A surface characterisation study (XPS) of the lead flotation stage, with and without cyanide, indicated that the reagent interacted specifically with the galena and pyrite minerals. It was possible to correlate the surface absorption of the cyanide on the lead and iron sulphides with improvements to the flotation performance using the combination of surface spectroscopy and laboratory flotation Testwork.