Coextraction and successive selective stripping of cerium(IV) and thorium from monazite leach solutions with tributyl phosphate (TBP)

Resumo

Solvent extraction of Ce(IV) and Th(IV) from 8 M HNO₃ with TBP in kerosene was studied. The dependence of the extraction on the TBP concentration, kind of diluent, O/A phase ratio, and contact time was examined. The extraction efficiency reaches 99.3 and 97.7% for Ce and Th, respectively, at 5% TBP in kerosene, 1/1 O/A phase ratio, and 5 min contact time. Successive selective stripping of Ce(III) and Th(IV) from the loaded organic phase was reached at 1.1 M H₂O₂ concentration, 10 min contact time, 3/1 O/A phase ratio, and room temperature (25 ± 2°C). After stripping of cerium, the remaining organic was contacted with H₂O for thorium stripping at 5 min contact time, 2/1 O/A phase ratio, and room temperature (25 ± 2°C).