Solvent extraction of Th from aqueous chloride solutions with the ThO 2 content below 1 g l !1 obtained in processing perovskite was studied. Di(2-ethylhexyl) hydrogen phosphate, octanol, and tributyl phosphate were tested as extractants. Thorium is extracted most efficiently and selectively from concentrated aqueous CaCl 2 with tributyl phosphate. The conditions for preparing solid concentrate containing about 20 wt % Th were found.Increased interest in Th as an additional energy source for nuclear power engineering is caused by inevitable exhaustion of uranium deposits in future. The recovery of Th in the course of industrial processing of rare-metal ores is one of the most promising routes for preparing thorium concentrates [1]. In this study we examined the recovery of thorium from solutions formed in integrated processing of perovskite.In our experiments we used perovskite from Afrikanda deposit prepared for industrial processing, with the following content of components (wt %): (Nb + Ta) 2 O 5 , 0.64 32.50; TiO 2 , 50.8356.8; SiO 2 , 0.123 1.93; Al 2 O 3 , 0.1531.30; Fe 2 O 3 , 0.4332.0; FeO, up to 1.44; La 2 O 3 (sum of rare-earth element oxides), 2.183 10.7; CaO, 26.3338.1; Na 2 O, 0.132.35; and ThO 2 , 0.073 0.14. Various schemes for integrated processing of perovskite were developed at the Tananaev Institute of Chemistry, Kola Scientific Center, Russian Academy of Sciences, for preparation of Ta 2 O 5 , Nb 2 O 5 , pigment-grade TiO 2 , and rare-earth metal concentrate. A process for efficient breakdown of perovskite with aqueous hydrogen chloride was developed. In this process, Ca, rare-earth elements, and Th are dissolved, whereas Ti, Nb, and Ta precipitate and are then converted into a commercial product by common procedures [2,3]. After precipitation of hydrolyzable metals (Ti, Nb, and Ta), the aqueous chloride solution has the following composition, g l 31 : HCl, 100 3200;CaCl 2 , 100 3150; ThO 2 , 0.13 0.2; Ln 2 O 3 , 6310; Fe 2 O 3 [Fe(II) + Fe(III) recalculated to Fe 2 O 3 ], 6 310; and TiO 2 , 1310. This solution contains also Na, Al, V, Mn, and several other elements. This multicomponent solution contains elements of essentially different types and is highly saline. Insufficient data on properties of these solutions hinder the development of a process for preparing thorium concentrate from perovskite. In some experiments, the extraction of Th from aqueous chloride solution formed after precipitation of hydrolyzable metals was studied. In other experiments, this solution was evaporated to increase the CaCl 2 concentration to 300 g l 31 and more. This preconcentration improves the extraction of Th, decreases the volume of the total process flow, and allows reuse of HCl for the breakdown of perovskite [4].The organic reagents used in our experiments were as follows: di(2-ethylhexyl) hydrogen phosphate (HDEHP) (Bayer, main substance content >98%), 1-octanol (main substance content about 98%), and tributyl phosphate (TBP) (pure grade). RED-1 (C 12 3 C 16 paraffin mixture) was used as diluent. The ex...
