Fundamental study on separation of uranium from other metals by solvent extraction with tributylphosphate or tributylphosphine oxide in molten naphthalene

The extraction behaviors of U and other metals has been studied as functions of the concentration of nitric acid or hydrochloric acid in aqueous media and as functions of the amount of naphthalene as diluents, when tributylphosphine oxide (TBPO) or tributylphosphate (TBP) was used as a extractant. Uranium could be quickly extracted over 95% from 25 cm3 of the 1 mol.dm-3 nitric acid solution with 150 mg of TBPO and 350 mg of naphthalene at 800C. On the other hand, about 80% of U could be extracted under better conditions, when 25 cm3 of 4 mol.dm-3 nitric acid solution and 1 cm3 of TBP and 3 g of naphthalene were used. In either case, the extraction phases could be easity separated as a solid by cooling to room temparature. Uranium could be separated from alkaline earth metals, transition metals and rare earth metals, and U was efficiently concentrated by extraction with molten naphthalene, compared with usual solvent extraction which used toluene, etc. (author)