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Abstract

A process for recovering gold from refractory auriferous iron-containing concentrate includes feeding the concentrate as an aqueous slurry to an acidic pretreatment step and treating the concentrate in the acidic pretreatment step with aqueous sulphuric acid solution to decompose carbonate and other acid consuming gangue compounds. The treated slurry is oxidized in a pressure oxidation step at a temperature in the range of from about 135.degree. to about 250.degree. C. under a pressurized oxidizing atmosphere while maintaining a free acid concentration of from about 5 to about 40 g/L sulphuric acid to cause dissolution of iron, formation of sulphuric acid and oxidation of substantially all oxidizable sulphide compounds to sulphate form with less than about 20% of oxidized sulphur being present as elemental sulphur during the oxidation step. Water is added to the oxidized slurry in a first repulping step to produce a repulped oxidized slurry with a pulp density in the range of from about 5 to about 15% solids by weight, the repulped oxidized slurry is subjected to a liquid-solids separation step to produce an acid and iron containing solution and oxidized separated solids, a portion of the acid and iron containing solution is recycled to the acidic pretreatment step, and gold is recovered from the oxidized separated solids.

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