Zirconium and hafnium separation with molten salt extraction in Sn–Cu–Zr–Hf and Cu–Zr–Hf alloy systems

Chemical-grade zirconium contains about 1–3 wt% hafnium, which is harmful for nuclear applications due to its high neutron-capture cross section. In the present paper, Zr-Hf separation in Sn-Cu-Zr-Hf and Cu-Zr-Hf alloy systems using molten salt containing CuCl2 or CuF2 was thermodynamically evaluated and lab-scale experiments on zirconium and hafnium separation in different molten salt systems were conducted. The best single-step Hf removal efficiency and Zr-Hf separation factor of about 95% and 9.0, respectively, were obtained with a NaCl-CaCl2-CuCl2 (3 wt%) molten salt system at 850°C and the CuCl2/Hf stoichiometric ratio of 1.5.