Application of -di(2-ethylhexyl)butanamide for mutual separation of U(VI) and Pu(IV) by continuous counter-current extraction with mixer-settler extractors

Ban, Yasutoshi  ; Hotoku, Shinobu ; Morita, Yasuji  

Continuous counter-current extraction using -di(2-ethylhexyl)- butanamide (DEHBA) as an extractant was performed with mixer-settler type extractors consisting of U-Pu extraction, scrub, U recovery, Pu back-extraction, and U back-extraction steps. The feed solution used in the continuous counter-current extraction was 3 mol/dm (M) nitric acid containing U(VI), Pu(IV), and simulated fission products. More than 99.9% of U(VI) and Pu(IV) in the feed was extracted by 1.9 M DEHBA at the U-Pu extraction step. The extracted Pu(IV) was back-extracted via contact with 0.3 M nitric acid in the Pu back-extraction step, and the ratio of Pu(IV) distributed to the Pu fraction stream was 82%. It was confirmed that 1.9 M DEHBA effectively recovered U(VI) in the U recovery step, and the ratio of U(VI) in the Pu fraction stream was less than 1%. The extracted U(VI) was back-extracted in the U back-extraction step, and more than 98% of U(VI) was recovered in the U fraction stream.