National University of Science and Technology MISiS, Moscow, Russia:

V. A. Sokolov, Professor, Doctor of Technical Sciences, e-mail: va235-sokolov@yandex.ru
S. S. Kirov, Associate Professor, Candidate of Technical Sciences, e-mail: kirovss@list.ru
E. V. Bogatyreva, Professor, Doctor of Technical Sciences, e-mail: helen_bogatureva@mail.ru

D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:
M. D. Gasparyan, Professor, Doctor of Technical Sciences, e-mail: migas56@yandex.ru

This paper analyzes the current status of zirconium dioxide industry. In particular, the paper examines two sites: Vilnohirsk Mining and Metallurgical Works in Ukraine and Chepetsky Mechanical Plant in Russia, which produce commercially pure zirconium dioxide from zircon concentrate. The paper shows that the current commercial production of zirconium dioxide is based on zircon chlorination or zircon sintering with potassium fluosilicate, the processes that involve multiple stages and are environmentally unsafe as they generate large quantities of hazardous liquid waste. The prospective commercial production of zircon concentrate in Russia creates the need in an efficient, environmentally friendly processing technology to produce zirconium dioxide in the first place. The paper considers the outcomes of research conducted by MISiS and aimed at developing environmentally friendly processes to obtain zirconium dioxide from zircon concentrate. The authors established that a process of carbothermic decomposition of zircon by melting it in a heavyduty electric arc furnace could potentially be applied. A series of trial heats conducted with zircon-carbon burdens showed a triple reduction in silica content in the molten product. The paper also describes the results of trials that involved zircon decomposition in an electric arc furnace, gravity concentration of the molten product and production of commercial zirconium dioxide. The paper demonstrates the efficiency of using an electric arc furnace for zircon concentrate melting. The structures of molten baddeleyite-silica materials are described that were obtained in different production conditions. It is shown that, for efficient separation of baddeleyite from the glass phase, the baddeleyite crystal size should be at least 50 μm. The paper describes some potentially practicable production schemes for obtaining commercial zirconium dioxide with the maximum concentration of SiO₂ not exceeding 1 %. Key research objectives have been defined aimed at setting up a pilot production of zirconium dioxide from zircon concentrate using the carbothermic process.

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