Study of the Separation of Samarium and Europium Through Solvent Extraction

Center for Mineral research, Brazil

Abstract: The growing importance of rare earth elements (REEs) in recent decades is due to the large number of high technology applications. Currently, the separation of the REEs in industry is carried out mainly by solvent extraction (SX), and among the most common types of extractant are organophosphorus acids. The separation of adjacent rare earth elements is a major challenge due to the similarity in their chemical behavior, resulting in low selectivity of the extraction process. The addition of lactic acid in the extraction system can improve the extraction and selectivity of separating the elements europium (Eu) and samarium (Sm). The objective of this work was to compare the continuous solvent extraction of Sm and Eu with or without lactic acid in the extraction system. Continuous solvent extraction experiments showed that the addition of lactic acid favored extraction and selectivity of Sm/Eu separation. The best performance was achieved with a mixture of P507 (8%), D2EHPA (2%) and 0.3 mol L-1 of lactic acid, at pH 3.0, resulting in 96.5% recovery of europium in the organic phase. Future experiments will focus on the scrubbing of the loaded organic phase produced in the extraction stage.