PJSC “MMC “Norilsk Nickel”, Polar Division, Norilsk, Russia:

A. A. Efimov, Deputy Chief Engineer for technological developments, Copper Plant, e-mail: efimovaa@nornik.ru
A. S. Leonov, Director, Copper Plant
A. L. Kozhanov, Head of the Metallurgical Workshop, Copper Plant
I. S. Kuzmina, Chief Specialist, Center for Engineering Support of Production

The article presents the research findings on reduction of roasted cake of copper electrolyte slimes by a solid carbonaceous reductant. The optimal process conditions were determined experimentally. The various techniques of reduced calcine cake leaching were tested: in diluted sulfuric acid with the oxidizer introduction, in concentrated hydrochloric acid, by means of the sulfuric acid treatment. It was ascertained that sulphatization of reduced calcine cake under 200 oC allowed to transfer up to 99, 96 and 90% of nickel, copper and iron into solution, respectively. Besides, the obtained insoluble residue contains 20–30% of PGM and 20–30% of silica. The results of the research predetermine the partial modernization of PGM Concentrator technology which includes the processing of calcine cakes of copper electrolyte slimes to produce the bulk platinum concentrate by the carbonaceous reagent reduction followed by the sulphatization and water leaching. The advantages of the flowsheet are the retention of the current roasting and hydrometallurgical facilities, the decrease of precious metal losses by shifting from smelting to hightemperature reduction, the shortening of the production cycle time as well as material-in-progress by excluding the secondary anode electrolysis. The next step to improve bulk platinum concentrate implies ways of silica minimization in the copper electrorefining slimes by keeping the particles of degraded cell lining from ingress and defining of non-stick coating for the copper anode casting.

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