Reprocessing Th-based spent fuels with di-1-methyl heptyl methyl phosphonate using centrifugal extractors

In this paper, a reprocessing Th-based spent fuels process using di-1-methyl heptyl methyl phosphonate (DMHMP) as extractant was proposed and tested by multistage countercurrent extraction using batch simulation and centrifugal extractors. The analysis results of process samples show that the recovery of Th and U in 1A (co-extraction of Th and U), 1B (separation of Th from U) and 1C (stripping of U from organic to aqueous phase) section was more than 99.8% and 99.9%, respectively. The separation factor of Th from U and U from Th in 1B section was 5.9 × 103 and 7.1 × 103, respectively. Compared with Thorex process using TBP as extractant, the process could be operated under lower acidity and flow ratio of O:A due to the strong extraction ability of DMHMP. Thus, DMHMP would be a promising alternative extractant for Th-based spent fuels process.