I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials of the Kola Science Center of the Russian Academy of Sciences, Apatity, Russia:

E. K. Kopkova, Senior Researcher, e-mail: kopkova@chemy.kolasc.net.ru
M. A. Muzhdabaeva, Researcher
P. B. Gromov, Deputy Director for Science
V. Ya. Kuznetsov, Researcher

There is shown the possibility of low-temperature extraction of niobium and tantalum from chalcolamprite concentrate of Beloziminskoe deposit using nonaqueous solvent based on monatomic aliphatic alcohol and hydrofluoric acid (solvoprocess). Replacement of chemical reaction medium from water to organic one made possible the combination of concentrate decomposition and rare metal extraction in organic phase in one operation, decreasing decomposition temperature to 20 ^оС, and the process without outer heating (only at the expense of exothermal reaction heat). The process is the most efficient with the considerable excess of HF (S:L = 1:10), providing of both the high concentrate decomposition, and the favourable conditions for the following collective extraction of niobium and tantalum. Given the ratio of S:L = 1:10 and solvoprocess time (2.5 hours), more than 96% of Nb₂O₅ and 93% of Ta₂O₅ were extracted in organic phase for the single stage, with complete separation of uranium and thorium series' radionuclides in insoluble fluoride cake. Both radionuclides were efficiently separated after the sulphatization of fluoride cake with following water treatment at the temperature of 20 ^оС. The final product was obtained from hydrofluoric extracts, and contained 95% of Nb₂O₅, 1.5% of Ta₂O₅ and 2.10–4–5.10–2% (wt.) of impurity elements. This product may be used as a precursor for obtaining of fluoric salts of niobium and tantalum with their following processing with obtaining of metallic powder. There is offered the circuit diagram of chalcolamprite processing, which may be used for other tantal-niobates.

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