Bauman Moscow State Technical University, Moscow, Russia:

E. A. Eliseeva, Associate Professor, Chair for Chemistry, Candidate of Chemical Sciences
S. L. Berezina, Associate Professor, Chair for Chemistry, Candidate of Technical Sciences
V. S. Boldyrev, Associate Professor, Chair for Chemistry, Candidate of Technical Sciences, e-mail: boldyrev.v.s@bmstu.ru

D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:
Yu. M. Averina, Associate Professor, Chair for Innovative Materials and Corrosion Protection, Candidate of Technical Sciences

Establishment of criteria for optimizing technological processes for dissolving transition metal oxides, separating metal compounds from depleted ores, removing oxide deposits from thermotechnical equipment, and methods for cleaning compounds are of practical significance. Cobalt and its compounds are important in the production of hard and heat-resistant alloys as organic synthesis catalysts, as a component of trace elements, fertilizers and drugs. Cobalt isotopes are used as radioactive labels in medicine, as fuel in spacecraft batteries. To solve the technological issues of replenishing the deficit of cobalt by processing cobalt raw materials and its regeneration from industrial waste, it is necessary to conduct targeted research, study the regularities of its behavior during chemical processes (leaching of ores and concentrates) and during electrochemical dissolution (obtaining cobaltcontaining intermediate products for further alloy smelting). One of the important factors affecting the kinetic parameters of the dissolution of cobalt oxides is the characterization of surface properties of the solid phase. The surface structure of powdery Co₂O₃ oxide was studied by X-ray phase analysis and electron microscopy. The chemical dissolution of the oxide in aqueous solutions of HCl was studied. The sizes and shapes of cobalt oxide particles, the nature of their surface distribution were determined, and kinetic curves of the chemical dissolution of Co₂O₃ were constructed. The independence of the oxide dissolution mechanism on the acid concentration was established. The kinetic parameters of the process were calculated (specific dissolution rate, reaction order with respect to hydrogen ion). A comparative analysis of the correspondence between the obtained experimental and available literature data was carried out. The obtained experimental and calculated results are of interest in studying the regularities of the dissolution of solid oxide phases of cobalt in various electrolyte compositions.
The work was carried out with funding by D. Mendeleev Chemical Technical University of Russia, Project No. X-2020-011.

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