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ArticleName Thiocyanate-Cyanide Leaching of Gold from Gold-Copper Sulphide Flotation Concentrates
DOI 10.17580/tsm.2021.11.02
ArticleAuthor Lukianov A. A., Bogorodskiy A. V., Balikov S. V.

Irgiredmet JSC, Irkutsk, Russia:

A. A. Lukianov, Senior Researcher at the Metallurgy Laboratory, e-mail:
A. V. Bogorodskiy, Senior Researcher, Candidate of Technical Sciences, e-mail:
S. V. Balikov, Principal Researcher, Doctor of Technical Sciences


A technology for the recovery of gold from oxidized sulfide gold-copper flotation concentrates using a thiocyanate-based solvent has been developed. The technology involves low-temperature atmospheric oxidation (LTO) of sulfide gold-copper flotation concentrates with sulfuric acid, leaching of gold with a thiocyanate-based solvent, and adsorption of gold on activated carbon or ion-exchange resin. It was found that the recovery of gold into the leaching solution did not exceed 80% when using thiocyanate as a solvent. The recovery of gold from the LTO product of sulfide gold-copper flotation concentrates into the solution by the use of a mixture of thiocyanate and alkali metal cyanide was above 93%, which is comparable to conventional cyanidation. The technology includes preliminary leaching of the oxidized LTO product of flotation concentrates with a thiocyanate-cyanide mixture, at the pulp temperature of 95 oC and the designed concentrations of KSCN and NaCN of 1.0 and 0.5 g/L, correspondingly. Then, the pulp is transferred to adsorption leaching with the countercurrent flow of adsorbent and pulp streams. The main differences between the technology and conventional cyanidation are the elimination of alkaline treatment of the flotation concentrate LTO product; dissolution and adsorption of gold in acidic environments and at a high temperature; the maximum gold leaching time of 7 hours in total compared to 24 hours; the gold solvent (KSCN+NaCN) consumption of 4.5 kg/t of gold concentrate compared to 10 kg (NaCN). An engineering and economical comparison of cyanide and thiocyanate-cyanide for the recovery of gold from oxidized sulfide gold-copper flotation concentrates shows that the technology reduces the capital and operating costs for processing of the LTO product of sulfide gold-copper flotation concentrates by at least 20%.

keywords Grinding, sulfide gold-copper flotation concentrate, low-temperature atmospheric oxidation, leaching, thiocyanate, cyanide, gold, carbon adsorbent, ion exchange resin

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