Treatment of phosphate concentrates of rare-earth elements with low-concentration nitric acid in the presence of a sulfocation exchanger (sorption conversion) enables effective separation of rare-earth elements from phosphorus and fluorine. The effect of the nitric acid concentration and temperature on the efficiency of the sorption conversion of rare-earth element phosphates and the behavior of cationic impurities in the course of the sorption conversion were studied. It was shown that no selective transfer of thorium into solution could be achieved in the course of conversion and subsequent desorption with solutions containing nitric acid or ammonium nitrate.
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