Recovery of Gold and Silver from a Sulfidic Ore Cyanide and Chloride Leaching after Chlorination Roasting

Zhang, Jinrong ; Albert, Terence E. ; Fuerstenau, M. C. ; Hendrix, James L. ; Kappes, David W. ; Wan, R. Y.
Organization: Society for Mining, Metallurgy & Exploration
Pages: 16
Publication Date: Jan 1, 1993
A sulfidic flotation tailings ore, containing 1.14 gpt Au and 242.53 gpt Ag, was treated by low temperature chlorination roasting followed by cyanide or chloride leaching. Eighty per cent of Ag was recovered by cyanide leach when the ore was roasted at 350°C with 50 kg/ton calcium chloride. About seventy per cent of Au was made cyanide amenable by chlorination roasting at 400°C. A better Ag recovery, ninety per cent or over, was achieved by chloride (NaCl+HCl) leach. However, Au recovery was very poor by chloride leach. Ferric chloride, calcium chloride, and cupric chloride were compared as chlorinating agents for their effect on Au and Ag recovery. The study found that low temperature chlorination roasting is very effective for recovering Ag associated with stibnite and stannite. The best chlorinating agent for the test ore was found to be calcium chloride. Parallel roasting-leaching tests indicated that chlorination roasting was far superior over oxidation roasting for both gold and silver recovery.
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