In developing a method for possible low level isotopic enrichment, which uses to advantage the equilibrium isotope effect observed during U(1V)-U(VI) electron exchange reaction in sulphate solutions, details of a solvent extraction process involving high concentration of a mixture of U(IV) and U(VI) and at low acid concentrations, are described. The extraction behaviour of uranium under these conditions is discussed. During the extraction with amines, U(IV) tended to get oxidised in sulphate solutions.
