Institute of the Comprehensive Exploitation of Mineral Resources of the Russian Academy of Sciences (Moscow, Russia):
Chanturiya V. A., Chief Researcher, Doctor of Engineering Sciences, Professor, Academician of the Russian Academy of Sciences, vchan@mail.ru
Chanturiya E. L., Chief Researcher, Doctor of Engineering Sciences, Professor, elenachan@mail.ru
Minenko V. G., Leading Researcher, Candidate of Engineering Sciences, vladi200@mail.ru
Samusev A. L., Senior Researcher, Candidate of Engineering Sciences, andrey63vzm@mail.ru

The article presents the results of the evaluation of the most significant factors affecting zirconium recovery in the acid leaching of eudialyte concentrates, conducted using a mathematical model of a screening experiment. Based on the Plackett–Burman design, seven factors (temperature, nitric acid concentration, leaching time, preliminary grinding, ultrasonic and electrochemical effects, and high-voltage nanosecond electromagnetic pulses) affecting zirconium recovery into the product solution were studied. The regression coefficients and respective confidence intervals were calculated; the order of priority was determined for the significant factors. The dependence of zirconium recovery values on the parameters of the significant factors selected was experimentally established and a streamlined leaching regime was determined for the eudialyte concentrate, yielding 91 % Zr and 81 % ΣREM recovery into the product solution. It is shown that the eudialyte concentrate downstream of the third acid leaching stage (as compared with the feed concentrate sample) is characterized by a lower mass fraction of ZrO₂ and lower total SrO, BaO, and Ca, with higher mass fractions of Si, TiO₂, Ta₂O₅, Nb₂O₅, REM, which indicates intensive dissolution of eudialyte, nepheline and lamprophyllite in the leaching process, with accumulation of aegirine and loparite in the undissolved phase, containing a significant amount of rare-earth metals, the recovery of which requires the development of new efficient and economically feasible processes.

The studies were carried out with the financial support of the Russian Science Foundation (project No.16-17-10061-P). The authors would like to thank Candidate of Geological and Mineralogical Sciences E. V. Koporulina (IPKON RAS), Doctor of Engineering Sciences I. Zh. Bunin (IPKON RAS) and Doctor of Engineering Sciences E. V. Bogatyreva (National University of Science and Technology «MISiS») for their assistance in performing the experimental studies.

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