MMC “Norilsk Nickel”, Norilsk, Russia:

E. V. Shulga, Head of Laboratory, Center of Engineering Support of Production
A. I. Yurev, Executive Officer, Center of Engineering Support of Production, e-mail: ems@nk.nornik.ru

LLC “Institute Gipronikel”, Saint Petersburg, Russia:
E. M. Solovev, Senior Researcher of Laboratory of Metallurgy

Yuri Gagarin State Technical University of Saratov, Saratov, Russia:
N. D. Soloveva, Professor of a Chair “Chemical Technologies”

Choosing the optimal colloid regime is a crucial technological parameter as it determines the technical-economical indicators of electrolytic processes and cathode copper quality. The technology for electrorefining of copper, which is employed in the Polar Branch of MMC “Norilsk Nikel”, uses a complex of additives such as hide glue, thiourea and chlorine ions. The essential shortcoming of adding thiourea into copper electrolyte is that sulphide sulphur gets into cathode metal, which negatively affects the spiral extension indicator. In order to lower the concentration of thiourea in the electrolyte, it is recommended to use a supplementary additive called Aviton. It contains hexavalent sulphur which practically doesn’t get into cathode copper. Thiourea and Aviton additive’s effect on cathode polarisation of copper electrode in sulphate copper-nickel electrolyte was researched. Cathode polarisation curves for different concentrations of colloid additives are presented. It was determined that low concentrations of thiourea lead to cathode depolarisation, whilst increased concentration of Aviton inhibits cathodic deposition of copper. Laboratory and experimental-industrial tests with a goal to choose a regime for dosing of superficially active substances through fluent correction of concentration of thiourea and Aviton were carried out. The usage of “Aviton” additive in connection with hide glue and thiourea in laboratory tests lead to lowering the level sulphur in cathodic depositions to (5–6)·10^–4 % without deterioration of technological indicators of the process. The recommended colloid regime, based on the results of experimental-industrial tests (g/t of copper: 84 hide glue; 50 thiourea; 15 Aviton A) enabled a better visual appearance of copper cathodes and enhanced the chemical composition and spiral extension of cathode copper.

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