Separation of Rare-Earth Elements and Thorium in Sorption Conversion of Phosphate Rare-Earth Concentrate Produced in Nitric Acid Processing of Khibiny Apatite Concentrate

It is shown that REEs and thorium can be separated directly in the course of a sorption conversion of the phosphate rare-earth concentrate precipitated in nitric acid processing of the Khibiny apatite concentrate by introduction of compounds containing fluoride ions into the nitric acid solution used in the process. Under the optimal conditions, REEs are quantitatively adsorbed by the sulfo cation exchanger, whereas thorium mostly remains together with phosphorus and fluorine in the mother pulp. The influence exerted by the composition of compounds containing fluoride ions and process conditions on the separation efficiency of REEs and thorium. The suggested approach rules out formation of burial-requiring radioactive wastes with increased content of thorium.