Combined bio-hydrometallurgical process for gold recovery from refractory stibnite

The aim of this work concerns the recovery of gold by a combined biometallu rgical and hydrometallurgical treatment. The biooxidation of a refractory g old-bearing stibnite (antimony sulphide) favours the increase of gold recov ery during the subsequent hydrometallurgical process (cyanidation, adsorpti on onto activated carbon, desorption from activated carbon and electrowinni ng). Tests were conducted at laboratory scale utilising a refractory stibnite or e. The gold content of the sample was 32 g/t Au. Bacterial cultures utilise d In the biological test consisted predominantly of Thiobacillus genus, Aft er a long leach time (24 hours) low, recovery was obtained by direct cyanid ation (less than 4% Au), while a gold extraction yield of about 80% was ach ieved combining biometallurgical and hydrometallurgical process. Experimental results have shown the technical feasibility of the biometallu rgical pretreatment prior to the hydrometallurgical process. A complete pro cess flow-sheet has been outlined. (C) 2000 Elsevier Science Ltd. All right s reserved.