Using ternary molten salt with a molar ratio of NaCl:KCl:CsCl = 30:24.5:45.5 and ZrCl4 as raw materials to prepare a NaCl-KCl-CsCl-Cs2ZrCl6 composite electrolyte. Characterizing by XRD, ICP-AES, optical microscopy and SEM-EDS, the results showed that when the molar ratio of CsCl:ZrCl4 ≥ 2:1, Cs2ZrCl6 was generated according to the stoichiometric reaction; when the molar ratio of CsCl:ZrCl4 < 2:1, CsCl in molten salt was almost completely converted to Cs2ZrCl6, and there was a ZrCl4 phase. When the molar ratio of CsCl:ZrCl4 = 2:1, with the increase of the reaction temperature and reaction time, the concentration of zirconium ions first increased and then decreased. The optimized preparation process conditions are: the 2:1 molar ratio of CsCl to ZrCl4 in NaCl-KCl-CsCl, 500 °C of reaction temperature of and 3 h of reaction time. Under this condition, 99.68% conversion rate from ZrCl4 to Cs2ZrCl6 was obtained. Taking the prepared NaCl-KCl-CsCl-Cs2ZrCl6 composite electrolyte as a raw material, a preliminary study of molten salt electrolytic refining zirconium was carried out, and a refined zirconium product with a dendrite of 10.61 mm was obtained under the conditions of a zirconium ions concentration of 5%, an electrolysis temperature of 750 °C, a current density of 0.1 A/cm2, and an electrolysis time of 9 h, indicating that the composite electrolyte can be used for the electrolytic refining of zirconium.

Preparing zirconium chloride composite salts such as Cs2ZrCl6 can replace highly volatile ZrCl4 for studying molten salt electrolytic refining zirconium. The NaCl-KCl-CsCl-Cs2ZrCl6 composite electrolyte was prepared using ternary molten salt with a molar ratio of NaCl: KCl: CsCl=30: 24.5: 45.5 and ZrCl4 as raw materials. According to thermodynamic analysis, ZrCl4 preferentially reacts with CsCl to form Cs2ZrCl6 with strong stability. X-ray diffraction analysis showed that the main phase of the product was Cs2ZrCl6. ICP-DSC analysis showed that the conversion rate of ZrCl4 to Cs2ZrCl6 reached 99.68%. To verify the properties of this electrolyte, it is applied to molten salt electrolytic refining sponge zirconium. Studies have shown that this electrolyte system obtains dendrite zirconium products with a maximum grain size of 6.29mm, a system with more application prospects.