LLC NORD Engineering, Moscow, Russia¹ ; National University of Science and Technology MISIS, Moscow, Russia²

А. V. Кuznetsov, General Director¹, Assistant Professor of the Department of Energy Efficient and Resource-saving Industrial Technologies², e-mail: kuznetsov@mailnord.net
V. D. Khakhalin, Leading Process Engineer¹, Assistant Professor at the Department of Non-ferrous Metals and Gold², e-mail: v.hahalin@mailnord.net

National University of Science and Technology MISIS, Moscow, Russia

А. I. Bazlov, Associate Professor, Candidate of Technical Sciences, e-mail: bazlovmisis@gmail.com

Polar Branch of PJSC MMC Norilsk Nickel, Norilsk, Russia
P. G. Paymushkin, Chief Manager of the Technological Control Group of the Production Support Directorate, e-mail: PaymushkinPG@nornik.ru
P. V. Мalakhov, Chief Engineer of the Scientific Research Center of the Directorate of Production Development, e-mail: MalakhovPV@nornik.ru

The product of pyrometallurgical processing of copper-nickel sulfide concentrates of the Polar Branch of PJSC MMC Norilsk Nickel is copper-nickel matte, the cooled ingots of which are processed in JSC Kola MMC by the flotation method to obtain selective concentrates and a magnetic fraction. To increase the end-to-end extraction of nickel and copper into finished products during flotation separation, it is necessary to minimize the content of the second (polluting) metals in the target concentrates. The main factor affecting separation selectivity (all other things being equal) is the matte microstructure, the properties of which are determined by the cooling rate of the ingot, the direction of the heat sink and its composition. The paper presents studies of the structure of an industrial ingot under standard cooling conditions, the development of a physical and mathematical model of its cooling under the same conditions using the Pro Cast 2022 software package (ESI Group, France). The results of studying the ingot structure have shown a strong heterogeneity of the matte composition over the ingot cross-section and, consequently, large differences in thermal properties. Structures formed at a cooling rate in the crystallization range of more than 70 K/h and having a predominantly one-way heat sink have been identified as the least favorable for separation. Based on the simulation results, it is shown that the cooling rate in the crystallization temperature range, which ensures the maximum proportion of large (size more than 80–90 microns) copper sulfide grains of a shape close to spherical, is less than 70 K/h. Under such conditions, an increase in the selectivity of target metals during flotation separation is predicted.
The authors would like to thank the team of the Nadezhda Metallurgical Plant and the specialists of LLC NORD Engineering, leading technological engineers N. V. Verkhoturova and E. V. Abramov, who participated in the work.

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