METHOD OF THORIUM RECOVERY AND CONCENTRATION FROM PROCESS SOLUTIONS Russian patent published in 2003 - IPC

FIELD: hydrometallurgy; applicable for selective recovery of thorium from solutions containing other metals. SUBSTANCE: method includes sorption of thorium at pH 2.8-3.5 and temperature of 60-95 C on porous sulfacationite with subsequent washing of cationite and desorption of thorium with carbonate-containing solution. In this case, prior to sorption, introduced into initial solution is magnesium chloride in amount of 10-100 mg - equivalent Mg²⁺ per mg-equivalent of ions Th⁴⁺ in initial solution. After sorption, cationite is washer first with water and then with solution of MgCl₂ with concentration of 50-150 g/cu.dm. Filtrate after sorption is combined with washing waters. Introduced successively into combined solution are first potassium iodate, and then barium chloride and sodium sulfate. Pulp is filtered and radioactive iodate-sulfate cake is separated from deactivated solution which is directed for recovery and utilization of rare and trace metals. Thorium-containing eluate is treated with mineral acid, for instance, hydrochloric acid up to pH 0.5-2.0, heated up to 80- 100C, held at elevated temperature for 0.5-2h and alkali reagent, for instance, solution of hydroxide of sodium and/or ammonia up to pH5-8 is introduced. Formed pulp is set and filtered, sediment of thorium hydroxide and hydroxycarbonate is separated from mother liquor, combined with radioactive iodate-sulfate cake and directed for processing or for burial into special waste storage. Besides, magnesium chloride is introduced into initial solution in amount ensuring its content in solution before sorption of 50-150 g/cu.dm. Used for introduction into initial solution of magnesium chloride are natural and/or synthetic bishofite, and/or carnallite, and/or middlings, and/or wastes of carnallite raw material processing selected from carnallite dust of the first stage of carnallite dehydration or slime of carnallite chlorinators. KJO₃ is introduced in form of solution with concentration of 10-50 g/cu.dm in amount of 1.2-1.5 of solutions with concentration of 50-150 g/cu.dm in amount of 1.2-1.5 moles of Na₂SO₄ per mole of BaCl₂. EFFECT: higher degree of thorium recovery from scandium-containing solutions, higher degree of scandium cleaning from thorium and reduced irreversible losses of scandium with thorium in radioactive cakes and sediments. 5 cl, 2 tbl, 3 ex