Gold Leaching from Refractory Ores—Literature Survey

Abstract

This review is essentially an overview of the pretreatment processes for the refractory gold ores available in the recent literature. When gold is finely disseminated in sulphides, arsenosulphides, tellurides, carbonaceous and clayey materials direct alkaline cyanidation is not effective for gold extraction. However, pretreatment processes involving thermal oxidation, such as roasting, chemical oxidation, such as acid leaching, acid or alkaline pressure leaching; or biological oxidation such as bioleaching with T. Ferrooxidans liberates gold from refractory minerals. Gold is then recovered from the oxidized mass by alkaline cyanidation. Beside pretreatments, direct gold recovery from carbonaceous gold ores or concentrates with thiourea or CIL leach process is also feasible. Finally, some critical comments have been made to all the major pretreatment processes; and some recommendations for further R&D efforts have been suggested.