Electrorefining of Zirconium from Zircaloy-4 Cladding Hulls in LiCl-KCl Molten Salts

Zr electrorefining from Zircaloy-4 cladding hulls is demonstrated in LiCl-KCl-ZrCl 4 molten salts at 500°C. To examine the electrochemical behavior of Zr in molten salts, cyclic voltammetries and chronoamperometries are employed using a tungsten wire and Zr rod as a cathode and anode, respectively. Cyclic voltammetric measurement reveals multiple reduction/oxidation peaks caused by various oxidation states of Zr in the LiCl-KCl-ZrCl 4 system. Electrodeposition experiments at constant potentials, where the major reduction peaks are observed, reveal a reduction to insoluble ZrCl and Zr metal with solidified salts at a potential of −1.15 V vs. Ag/AgCl. Identical experiments using Zircaloy-4 cladding hulls as the anode exhibit similar voltammetric behaviors; however, additional reduction peaks associated with alloy components of Zircaloy-4 are found to be adjacent to the reduction potential of Zr. The purity of the recovered Zr deposits from Zircaloy-4 at a constant potential appears to be 99.94 wt% from a quantitative analysis using an inductively coupled plasma-atomic emission spectrometer (ICP-AES).