Siberian Federal University, Krasnoyarsk, Russia:
O. V. Yushkova, Leading Engineer, e-mail: olga_yushkova_1954@mail.ru
L. A. Isaeva, Associate Professor
P. V. Polyakov, Consultant Professor

Institute of solid state chemistry and mechanochemistry of the Siberian branch of the Russian academy of sciences (ISSC SB RAS):
E. G. Avvakumov, Principal Researcher

The influence of mechanical activation (MA) regime and the composition of alumina on the physico-chemical properties (dust index, granulometric and chemical composition (fluorine and iron content), dissolution rate in the molten cryolite, specific surface) have been studied. The alumina of grade G-00K supplied by various maufacturers was used before and after dry gas cleaning (fluorinated). The laser and visual methods, potentiometric titration method, X-ray phase analysis, the photocolorimetric method and the standard method for determining the dust index were used to determine the properties of alumina. It is shown that the MA of alumina of the Achinsk Combine (AC) in a centrifugal flow disk mill leads to a 2.3-fold decrease in the dust index and an increase in the dissolution rate by a factor of 2. With MA of alumina of the Nikolaev Alumina Combine (NAC) in the planetary mill of periodic action M-3, the dusting index decreases practically to zero. Mechanoactivation reduces the loss of raw materials from dusting. It is established that MA irrespective of the regime increases the reactivity of alumina and leads to the aggregation of particles. An increase in the rate of dissolution of alumina in cryolite will eliminate the formation of sediment, increase the productivity of electrolysis baths and increase the life of electrolyzers. Alumina after dry gas scrubbing is enriched with fluoride compounds, and MA increases the reactivity of the material.

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