Separation of americium from fission product lanthanides using Cyanex 301 extraction

The extraction behavior of bis (2,4,4-trimethylpentyl) dithiophosphinic acid (HBTMPDTP), purified from Cyanex 301, was studied for extracting Am
³⁺
and trivalent lanthanides (Lns). HBTMPDTP shows very high selectivity for Am. Separation factor (SF) of Am and Eu, SF
Am/Eu
, (trace amount) reaches a high value of 5.9×10
³
and SF
Am/(Pr+Nd)
(macro amount) is about 2×10
³
. The mathematical model for the distribution ratios and process parameters calculated for HBTMPDTP extraction was established and the calculated results were verified experimentally. In a five-stage countercurrent process, the extraction rates of Am and Lns were > 99.999% and 0.14%, respectively, to fulfill the separation requirements. The efficiency of this process was also verified in a cross-flow extraction experiment using a genuine Am-FPLns fraction. In the presence of TBP, the extraction of Am and Eu is enhanced, but their separation is reduced to some extent. A fairly good separation was achieved in a fractional extraction process using a mixture of HBTMPDTP and TBP in kerosene at low pH.