Electrochemical generation of stable uranium(IV) fluoride-sulphate solutions

Abstract

The electrolytic reduction of uranium(VI) to uranium(IV) was investigated exhaustively in a mixed fluoride-sulphate medium. Highly efficient reduction can be achieved and the discovery and confirmation of high solubility in the uranium(IV) fluoride-sulphate system has shown this reduction to be both an efficient and economic process. Conditions equivalent to 200 g l^–1 U^IV, 0.75 M HF and 0.5 M H₂SO₄(representing molar ratios of SO₄^2– : U = 1.5: 1 and F^– : U = 1 : 1) were demonstrated as optimum for both U^IV solubility and U^VI reduction efficiency. Cell reduction efficiency and membrane ion transport data together with solubility and stability data for the reduced U^IV species are presented. The mechanisms and factors governing the observed results are discussed.