Demonstration of the LUCA process for the separation of americium(III) from curium(III), californium(III), and lanthanides(III) in acidic solution using a synergistic mixture of bis(chlorophenyl)dithiophosphinic acid and tris(2-ethylhexyl)phosphate

Abstract

The LUCA process was developed at Forschungszentrum Jülich for the selective separation of Am(III) from an acidic solution containing the trivalent actinides Am(III), Cm(III), and Cf(III) as well as lanthanides. A mixture of 0.4 mol/L bis(chlorophenyl)dithiophosphinic acid and 0.15 mol/L tris(2-ethylhexyl)phosphate dissolved in 20% isooctane/80% tert-butyl benzene was used as the extractant. The process was carried out in centrifugal contactors using an optimized flowsheet involving 7 stages for extraction, 9 stages for scrubbing and 8 stages for back-extraction. Very encouraging results were obtained. A high feed decontamination factor was obtained for Am(III) (>1000), and recovery in the product after stripping was higher than 99.8%. The Am(III) product was contaminated with 0.47% Cm(III). More than 99.9% Cf(III), Eu(III) and >99.5% Cm(III) inventories were directed to the raffinate and the contamination with Am(III) (<0.08%) was low. The experimental results were in good agreement with the predictions of a computer code.