Kola MMC, Monchegorsk, Russia

P. M. Anisimov, Head of the Carbonyl Nickel Division, Nickel Electrolysis Shop

Gipronikel Institute LLC, Saint Petersburg, Russia
L. V. Biketova, Senior Researcher, Hydrometallurgy Laboratory, Candidate of Technical Sciences
Yu. N. Lisakov, Senior Researcher, Candidate of Technical Sciences
N. P. Chuprynin, Category Engineer, Hydrometallurgy Laboratory, e-mail: chupryninNP@nornik.ru

In 2022, there was a sharp increase in the demand of domestic enterprises for coarse-grained nickel powders of the PNK-2K9 and PNK-2K10 grades. Increasing productivity by several times required changing the technology of their production and the equipment used. The pilot tests conducted at the Carbonyl Nickel Division of the Nickel Electrolysis Shop at JSC Kola MMC contributed to determining the optimal parameters for the formation of coarse-grained nickel powders. The «delicate» process of producing powders of a given morphology is based on a clear and precise compliance with the temperature range in the upper zone of the decomposer and the flow rate of nickel tetracarbonyl vapors supplied to the decomposer. In order to optimize the sieving of powder, an equally important stage in the production of coarse-grained powders of the PNK-2K9 and K10 grades, the authors carried out experiments on sieving the powder feedstock on screening machines of various types. The experiments showed the superiority of the impact-type vibrating screen compared to the non-impact vibrating screen. The main problem requiring additional research is the carburization of nic kel, which leads to instability of the carbon content in the finished product. The morphology of the resulting particles shows that coarse-grained powders are conglomerates of baked particles under local overheating conditions. The most efficient method to reduce the carbon content in nickel powders is high-temperature annealing in a hydrogen atmosphere, as confirmed by a series of experiments. Factoring into the degree of the carbon reduction during annealing (from 0.6 to 0.016%), further research can be carried out in the field of reducing ennobling temperature, since the target value (0.28%) can obviously be achieved at a significantly lower temperature.

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