The separation of the trivalent actinides (III) americium and curium from the lanthanide group belongs to the most difficult PARTITIONING processes. The present paper describes a continuous process (ALINA) which uses a mixture of aromatic dithiophosphinic acid and TOPO as an extractant. The ALINA process was tested in a miniature centrifugal extractor battery with the aid of a 24-stage flowsheet consisting of 8 extraction, 8 scrubbing and 8 stripping stages. The An(III)/Ln(III) feed was an Am-241- and Cm-244-tracered synthetic solution whose lanthanide concentration corresponded to a real DIAMEX back-extraction process solution. With the aid of this flowsheet 99.9% of the americium, but only 80% of the curium was extracted and back-extracted. The actinide(III) product stream was only contaminated with approx. 2 mass percent of the lanthanides so that the ambitious aim of < 5% was achieved. Considering the slow extraction kinetics and the efficiency of the extraction stages, the experimental results for americium are in good agreement with theoretical calculations.

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