Patent ID: 8753420

Claim:
A method for selective recovery of americium from an A1 aqueous phase which contains at least 0.5 mol/L of nitric acid, americium, curium and fission products including lanthanides, but which is free of uranium, plutonium and neptunium or which only contains these three last elements in trace amounts, the method comprises at least the following steps: a) extracting the americium and a part of the lanthanides from the A1 aqueous phase, by circulating the A1 aqueous phase in a first extractor, as a counter-current to an organic phase non-miscible with water, which contains a solvating extractant capable of extracting more americium than curium from an acid aqueous phase, and optionally an acid extractant, in an organic diluent; b) washing the organic phase stemming from step a), by circulating this organic phase in a second extractor, as a counter-current to an A2 aqueous phase which contains at least 0.5 mol/L of nitric acid; c) optionally adding to the organic phase stemming from step b) some acid extractant if the latter is not already present in this phase; d) selectively de-extracting the americium present in the organic phase stemming from step b) or step c), by circulating the organic phase stemming from b) in a third extractor as a counter-current to an A3 aqueous phase which has a pH at least equal to 1 and which contains one or several complexing agents; and e) de-extracting the lanthanides present in the organic phase stemming from step c), by circulating this organic phase in a fourth extractor, as a counter-current to an A4 aqueous phase which contains less than 1.5 mol/L of nitric acid; and wherein the ratio between flow rates at which the organic phase and the A1 aqueous phase circulate in the first extractor and the ratio between flow rates at which the organic phase and the A2 aqueous phase circulate in the second extractor are selected so that the extraction factor for americium obtained in each of steps a) and b) is greater than 1 and that the extraction factor for curium obtained in each of steps a) and b) is less than 1.