This paper deals with the application of the cyanide process to recover gold from a pyrite concentrate produced by means of differential flotation. This concentrate before cyanidation contains from 0.09 oz. to 0.14 oz. gold per ton, of which only about 60 per cent is recoverable. The rest is so fine that it remains interlocked in the pyrite and therefore is not acted on by the cyanide. The concentrate also contains about 15 per cent pyrrhotite and 0.4 per cent chalcopyrite, both of which are cyanicides. The cyanicidal effect of the pyrrhotite is inhibited by preacrating the pulp with lime, and maintaining a high lime alkalinity during cyanidation. The effect of the chalcopyrite is reduced as far as possible by removing those particles which are free by means of a further flotation step immediately prior to cyanidation.
ammonium sulphate, cyanide, gold extraction, pyrite, pyrrhotite, Consumption, cyanide, Gold, Plants, pyrite, test, Tests