National University of Science and Technology MISiS, Moscow, Russia:
E. V. Bogatyreva, Professor of the Department of Non-Ferrous Metals and Gold, e-mail: Helen_Bogatureva@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 promising sources of rare earth metals and zirconium in Russia. The main goal of the present study is to investigate the reactivity of the eudialyte concentrate in the alkaline dissection process to determine the conditions that ensure max complete and selective extraction of silicon into the solution and to obtain a concentrate, which is enriched in rare-earth (REM) and rare metals (Zr, Ti, Nb, Ta) and suitable for subsequent effective acid processing. The results of technological studies of alkaline decomposition of eudialyte concentrate and its intensification using preliminary short-term mechanoactivation are presented. As a result, the formation of phases of zirconium silicates Na₁₄Zr₂Si₁₀O₃₁, Na₈ZrSi₆O₁₈, Na₄ZrSi₃O₁₀, Na₂ZrSi₂O₇ and their partial solubility in alkaline solutions have been established. A difference in the morphology of the components of the eudialyte concentrate, the eudialyte and aegirine phases, was established, which ensured the selective extraction of silicon from the eudialyte phase. A significant increase in the filtration rate of the alkaline leaching pulp of a mechanically activated eudialite concentrate after an increase in the duration of the process to 8 hours has been revealed. A basic combined (alkaline-acid) scheme for processing eudialyte concentrate is proposed. Optimal regimes of preliminary mechanoactivation, alkaline and acid leaching are determined, which ensure selective silicon recovery into the solution by 64% and concentration of Zr, REM, Nb, Ti in the precipitate during the alkaline treatment stage, and then acidic decomposition of the precipitate into 95, 94, 60 and 95% respectively.

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