Company “Nornickel”, Norilsk, Russia:

I. S. Bezzubenkova, Chief Specialist of the Copper Plant Laboratory of Engineering Support of Production, Center for Engineering Support of Production
M. A. Litvyak, Chief Engineer of the Copper Shop at Copper Plant
E. V. Salimzhanova, Deputy Director, Center for Engineering Support of Production, Candidate of Chemical Sciences, e-mail: SalimzhanovaEV@nornik.ru
O. V. Bolshakova, Head of the Copper Plant Laboratory of Engineering Support of Production, Center for Engineering Support of Production

Since 2018, сompany “Nornickel” Polar Division has been receiving goldcontaining gravity concentrate from Bystrinsky GOK (Chita). The gravity concentrate batches are treated at the copper matte converting section in the Smelting Shop of Copper Plant and at PGM Concentrator together with copper electrolytic slimes. Gold is extracted as a part of PGM Concentrator commercial products, platinum concentrates. Addition of the gravity concentrate increases the operation costs and materials consumption of the metallurgical operations. Moreover, high content of lead and arsenic poses risks to deteriorate the quality of commercial products (copper cathodes and precious metals concentrates) made at Copper Plant. An option of a separate cycle for the gravity concentrate treatment to obtain a selective product will be discussed. A process including the gravity concentrate oxidizing roasting, the sulfuric acid leaching of cinder in the presence of sodium hypochlorite and the precipitation of gold concentrate from the leach solution by sodium sulfite was developed based on the laboratory study. The new process was tested on a bench-scale. The optimal operating conditions of manufacturing operations are selected and 94.0–97.6% gold concentrate was produced. It is established that the completeness of gold extraction from the gravity concentrate by the proposed method mainly depends on the content in the product of the fraction with a size of –0.071 mm. As a result of the implemented investigations, it was determined that direct extraction of gold into gold concentrate was 76–93%. The new process provides certain advantages such as the recovery of gold as a highly selective product with the minimum number of operations and the possibility to use the existing equipment and the reagents of the current process. Besides, the separate treatment of gravity concentrate and copper slime prevents lead and arsenic impurities from reporting to PGM Concentrator, thus eliminating the risk of degradation for the main performance indicators and the product quality.

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