Zirconium-hafnium electrolysis

Electrolysis. Electro winning of hafnium, zirconium, and titanium has been proposed as an alternative to the KroU process. Electrolysis of an all chloride hafnium salt system is inefficient because of the stabiHty of lower chlorides in these melts. The presence of fluoride salts in the melt increases the StabiHty of in solution and results in much better current efficiencies. Hafnium is produced by this procedure in Erance (17). 

Zirconium(iii) and hafnium(iii) species have been generated in solution by the sodium amalgam reduction of ZrC in acetonitrile and by electrolysis of the same solution using a mercury cathode. ... 

Preparation of uranium metal. As discussed previously, some nuclear power plant reactors such as the UNGG type have required in the past a nonenriched uranium metal as nuclear fuel. Hence, such reactors were the major consumer of pure uranium metal. Uranium metal can be prepared using several reduction processes. First, it can be obtained by direct reduction of uranium halides (e.g., uranium tetrafluoride) by molten alkali metals (e.g., Na, K) or alkali-earth metals (e.g.. Mg, Ca). For instance, in the Ames process, uranium tetrafluoride, UF, is directly reduced by molten calcium or magnesium at yoO C in a steel bomb. Another process consists in reducing uranium oxides with calcium, aluminum (i.e., thermite or aluminothermic process), or carbon. Third, the pure metal can also be recovered by molten-salt electrolysis of a fused bath made of a molten mixture of CaCl and NaCl, with a solute of KUFj or UF. However, like hafnium or zirconium, high-purity uranium can be prepared according to the Van Arkel-deBoer process, i.e., by the hot-wire process, which consists of thermal decomposition of uranium halides on a hot tungsten filament (similar in that way to chemical vapor deposition, CVD). 

Ivanovskii, L.E., Chashchikhin, V.A., and Batukhtin V.P. (1970). Refinement of hafnium and zirconium in molten chlorides, Tr.Inst.Electrokhim., Ural.Nauchn.Tsentr., Akad.Nauk. SSSR 15, 18-23. Martem yanova, Z.S., Petenev, O.S., Baraboshkin, A.N., and Ivanovskii, L.E.(1974). Structure of coherent hafnium deposits prepared by the electrolysis of a molten chloride, Ibid 21, 53-55. 

Kirihara, T., Nakagawa, L, Seki, Y., and Honda, Y. (1989) Process of separation of hafnium from zirconium by molten salt electrolysis. US Patent 4 857 155. 

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