MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Gold Cementation from Ammonium Thiosulfate Solution by Zinc, Copper and Aluminium Powders
Harunobu ArimaToyohisa FujitaWan-Tai Yen
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2002 Volume 43 Issue 3 Pages 485-493

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Abstract

Gold cementation test was conducted without de-aeration by using zinc, copper and aluminium powders from an ammonium thiosulfate solution contained 8 mg/l Au. The amount of metal powder was varied in the range of 30–450 Metal/Gold mass ratio. The solution composition was 1–5 mol/l NH4OH, 0.01–0.05 mol/l CuSO4∗5H2O, 0.2–0.4 mol/l (NH4)2S2O3 and pH 9.5–10.5. The results indicated that the gold was effectively recovered from a solution of lower ammonia and copper concentrations and higher thiosulfate concentration. The optimum reagent composition for the gold cementation from the ammonium thiosulfate solution was founded to be 1 mol/l NH4OH, 0.01 mol/l CuSO4∗5H2O and 0.4 mol/l (NH4)2S2O3 at pH 9.5. 100% of gold was recovered by zinc and aluminium powders at a Metal/Gold mass ratio of 30. Copper powder recovered 93% of gold at a Metal/Gold mass ratio of 50. Zinc might re-generate thiosulfate concentration and precipitate most of copper in the solution. Aluminium precipitation might recover gold with less amount of copper deposition and some thiosulfate reduction. Copper precipitation reduced a small amount of thiosulfate concentration and greatly increased copper concentration. Ammonia concentration stayed constant during cementation process.

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© 2002 The Mining and Materials Processing Institute of Japan
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