Metallurgy and Beneficiation Institute JSC, Almaty, Republic of Kazakhstan:

S. M. Kozhakhmetov, Chief Researcher
S. A. Kvyatkovskiy, Head of Laboratory, e-mail: kvyatkovskiy55@mail.ru
A. S. Semenova, Leading Engineer

Kazakhmys Corporation LLP, Almaty, Republic of Kazakhstan:

Ye. A. Ospanov, Chief of Department

The problem of efficient processing of refractory gold ledge ores is reviewed. Among the gold ledge ores of the Central Kazakhstan, the arsenic and cobalt deposit Sayak-4, discovered in the 1950s, has not been processed so far due to its special refractoriness and difficult beneficiation. Therefore, for efficient processing of such hard-to-beneficiate gold ledge ores, we proposed a process of selective pyrometallurgical reduction (SPR process) based on a pyrometallurgical extraction of gold from refractory ores. The article is devoted to an experimental study of selective pyrometallurgical reduction (SPR) process for refractory gold-arsenic-cobalt ledge ores of the Sayak-4 deposit (gold), in conditions of reduction smelting, with recovery of noble metals to the iron and copper collector alloys. Extensive tests were conducted under reduction conditions using the ores of Sayak-4 deposit containing (%): Au — 3.5 g/t; Ag — 1.76 g/t; Fe — 3.95; Cu — 0.01; C — 1.93; S — 1.0; As — 3.3; Co — 0.05; SiO₂ — 38.3; CaO — 23.6; Al₂O₃ — 4.56; MgO — 0.73. Metallurgical coke was used as a reduction agent, and in some cases of smelting iron and copper oxides were used as a fluxes forming metal phase. Under an extensive laboratory smelting at 1450 °С, with additional charging of iron, copper oxides and coke to the ore, we showed an optional production of iron and copper collector alloys containing 16.2–16.4 g/t Au and 11.9– 20.4 g/t Ag. The resultant slag contained 0.38–0.50 g/t Au and 0.2– 3.2 g/t Ag. Also, direct recovery to the metal alloys reached 91% in case of gold and silver. In conditions when the alloys are transfered to refining and a part of the slag is returned to the electric smelting flux, the end-to-end recovery of noble metals to commercial products will be at the level of 90%.
The paper is published within a project of a grant financing of scientific investigations No. 850/ГФ4.

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