INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE, v.13, no.4, pp.3897 - 3909
Abstract
It has been believed that high purity Zr metal is hard to be prepared from Zr alloys in LiCl-KCl salts since Zr has various redox reactions in LiCl-KCl including insoluble ZrCl formation and disproportionate reaction between Zr and Zr4+. We examined electrolytic Zr recovery from Zircaloy-4 by controlling anodic potential at five concentrations of ZrCl4 in LiCl-KCl salts. Anode potential of - 0.9 V (vs. Ag/AgCl) was applied to prevent the elements except Zr being dissolved from the anode into the electrolyte. Experimental results showed Zr with purity of over 99.9% was recovered and all alloying elements were analyzed below their detection limit in ICP-MS. In addition, at low ZrCl4 concentrations of 0.1 and 0.5 wt.%, the chemical form of the cathode deposits was Zr metal without ZrCl while only ZrCl without Zr metal was recovered at the high ZrCl4 concentration, 2.0 and 4.0 wt.%. At the ZrCl4 concentration of 1.0 wt.%, both Zr metal and ZrCl were recovered. Therefore, preparation of high purity Zr metal from Zr alloys is feasible in LiCl-KCl at low concentration of ZrCl4.