Zirconium electrolysis cell

Fig. 7.3. Zirconium Electrolysis cell (Shelton, S. M., Zirconium Production Methods, Metallurgy of Zirconium, McGraw-Hill. U.S.A.E.C. Copyright).

Electrolysis. Electrowinning of zirconium has long been considered as an alternative to the KroU process, and at one time zirconium was produced electrolyticaHy in a prototype production cell (70). Electrolysis of an aH-chloride molten-salt system is inefficient because of the stabiUty of lower chlorides in these melts. The presence of fluoride salts in the melt increases the stabiUty of in solution, decreasing the concentration of lower valence zirconium ions, and results in much higher current efficiencies. The chloride—electrolyte systems and electrolysis approaches are reviewed in References 71 and 72. The recovery of zirconium metal by electrolysis of aqueous solutions in not thermodynamically feasible, although efforts in this direction persist. 

High temperature cells with solid electrolytes of zirconium dioxide have been investigated for the electrolysis of H2O vapor and as fuel cells for the generation of electric power. Examples include the combustion of synthesis gas (CO-H2 mixtures) in cells at temperatures of 1300 K. 

The rate of electrolysis is this near-commercial scale cell is 5-6 Ib/hr of zirconium at a current efficiency of about 60 per cent, and the overaU rate of production is 2-5 Ib/hr. Oxygen contents range from 0-06 to 0-09 per cent, nitrogen is about 0-003 per cent and carbon contents are about 0-02 to 0-06 per cent. Other impurities in typical electrolytic powder are as follows ... 

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