Polar Division of MMC “Norilsk Nikel”, Norilsk, Russia:

A. V. Kelekhsaev, Chief Specialist (Center of Engineering Maintenance of Production)
I. S. Kuzmina, Chief Specialist (Center of Engineering Maintenance of Production), e-mail: kuzminais@nk.nornik.ru
A. L. Kozhanov, Chief Engineer of Metallurgical Shop of Copper Plant
A. S. Leonov, Head of Metallurgical Shop of Copper Plant

The paper presents the results of research on high-temperature pressure leaching of cinder cakes of copper and nickel electrolyte slimes in sulfuric acid solution under inert conditions of argon atmosphere. The following optimum leaching modes were determined experimentally: 185 ^oC, C(H₂SO₄) 250 g/dm³, PAr 1,4 MPa, residence time 2 hours, paraform consumption 2 g/dm³. It is proven that the process permitted to recover more than 90% of nickel and copper into solution. Moreover 99% of platinum, palladium, rhodium, gold and silver as well as more than 90% of ruthenium and iridium are accumulated in the insoluble residue. It should be noted that after pressure leaching the cake contains a considerable amount of silicon along with high PGM content. Silicon is listed in the impurities limited in platinum concentrates supplied to “Krastsvetmet” Plant in Krasnoyarsk. It is well known that silicon enters the PGM Concentrator circuit mainly via copper slimes from Copper Tankhouse. As electrolyte used in copper anodes electrorefining has high acidity, the slimes contain not only the impurities from copper anodes but also flakes of silicate bricks used for electrolysis baths lining. The problem of high silicon content in the cake from pressure leaching can be solved via selection of the electrolysis baths lining capable to provide continuous service being exposed to hot sulfuric acid solutions. Optimization scheme of electrolyte slimes processing at the PGM concentrator of Copper Plant was proposed based on the study results. The advantages of this technology are as follows:
1. Utilization of existing roasting and hydrometallurgical facilities;
2. Significant simplification of the flowsheet and decrease of the production cycle period as well as the volume of non-finished production due to elimination of smelting and electrolysis stages

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4. Ter-Oganesyants A. K., Lapshin D.A., Anisimova N. N., Grabchak E. F., Ilyukhin I. V. Poluchenie vysokoselektivnykh kontsentratov platinovykh metallov iz khloridnykh rastvorov (Obtaining of high-selective concentrates of platinum metals, made of chloride solutions). Tsvetnye Metally = Nonferrous metals. 2007. No. 7. pp. 68–71.