Solvent Extraction Separation of Cerium and Yttrium from Other Rare Earth Fission Products

Abstract

A batch solvent extraction process was developed to separate Y/sup 91/ and Ce/sup 144/ from the rare-earth fission product elements in HNO/sub 3/ solution by extraction intc a di(2-ethylhexyl)phosphoric acid organic phase. Yttrium is first extracted from a 1N HNO/sub 3/ solution into the organic phase. Cerium is oxidized by KMnO/sub 4/ to the tetravalent state prior to its removal by a second batch extraction. A Ce/sup 144/ product is recovered from the organic phase by back extraction as the trivalent ion into a H/sub 2/O/sub 2/-- HNO/sub 3/ aqueous phase. The remaining rare earths contain Pm/sup 147/ which can be separated and recovered by conventional ion exchange techniques. The process was demonstrated in a pilot plant run from which 129,000 curies of high- purity Ce/sup 144/ was recovered in good yield. (auth)