Phase Crystallization in the CePO4–NaF System

The phase crystallization in the CePO4–NaF system was studied in order to develop an industrial process for rare earth metal recovery from a phosphate salt melt formed upon liquation of the rare earth ores from the weathering crust of the Tomtor deposit. The phosphate salt melt accumulated TR2O3, P2O5, Sc2O3, and Y2O3, and the silicate melt contained Fe2O3 and Nb2O5. Chemical reactions between CePO4 and NaF in the phosphate salt melt induced crystallization of the double phosphate Na3Ce[PO4]2 and the fluoride phosphate Na2CePO4F2. The products of melt crystallization in the CePO4–NaF system incongruently decomposed in dilute mineral acids (HNO3) to give an insoluble precipitate containing CeO2 and CeF3.