National University of Science and Technology “MISiS”, Moscow, Russia:
E. V. Bogatyreva, Professor of the Chair of Non-Ferrous Metals and Gold, e-mail: nelen_vogatureva@mail.ru
O. V. Khokhlova, Assistant of the Chair of Non-Ferrous Metals and Gold

JSC “Solikamsk Magnesium Plant”, Solikamsk, Russia:

A. V. Chub, Deputy Head of the Experimental Workshop

A. G. Ermilov, Independent Expert

Eudialyte is one of the most promising sources of rare-earth elements and zirconium in Russia. The main purpose of this research is to study the reactivity of the components of the eudialyte concentrate during the alkaline dissection to determine the conditions that ensure full and selective extraction of silicon into the solution. The features of changing behaviour of size distribution and the specific surface of eudialyte concentrate in the process of short-term preliminary mechanoactivation (MA) in “soft” and “hard” regimes were revealed. The changing behaviour in the specific surface area of the eudialyte concentrate in respect with the duration of short-term preliminary MA is similar to the results of studies conducted with other concentrates of rare metals. Differences in the morphology of the components of the eudialyte concentrate after MA, e. g. eudialyte and aegirine, which resulted from a difference in their physicomechanical and energy properties, were established. The effect of short-term preliminary MA (not more than 2.5 minutes) provided during alkaline leaching (solid : liquid ratio S:L = 1:10; CNaOH = 40%; T = 100 ^oC; в = 6 h) is shown to increase the extraction of silicon into the solution from 1 to 55 %. The obtained results are confirmed by the data of thermodynamic calculations and indicate the formation of zirconosilicates. There is a low rate of filtration of the pulp (~0.07 l/(m²·min)).

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