Consecutive recovery of uranium oxides from uranyl-containing molten alkali metal sulfate electrolytes

The oxygen coefficient (atomic ratio O/U) of a cathode product and the cathode current yield in consecutive recovery of uranium oxides from molten salt mixtures (nLi₂SO₄ + (1 ? n)Cs₂SO₄) + UO₂SO₄ and (Li,Na,K)₂SO₄ + UO₂SO₄ in air were analyzed as dependent on the electrolyte and the mean solvent-salt cation radius. The increasing mean solvent-salt cation radius and decreasing UO₂SO₄ concentration in the electrolyte during long-term electrolysis suppress the solvolysis of uranyl ions and decrease the oxygen coefficient in the cathode product. The cathode current yield decreases systematically during electrolysis and drops to zero long before the uranium is completely recovered from the melt. The ultimate uranium recovery increases as the mean solvent-salt cation radius increases.