Low-Carbon and Sustainable Electrochemical Synthesis of Large-Particle Titanium from TiO2 in Mixed Molten Salts

This study develops a two-step electrolysis process using TiO 2 as the raw material for large-particle titanium powder production in fluoride-chloride molten salts. TiO 2 is first dissolved in NaF-K 2 TiF 6 molten salt at 850 °C to form Ti–O–F complexes, and then titanium is electrodeposited at 1.2 A/cm 2 for 4 h to produce sponge-like titanium powder. The obtained titanium powder has an average particle size of approximately 30 μm and an oxygen content of about 0.59 wt %. Due to the high oxygen content, secondary electrorefining is performed in NaCl-KCl melts, investigating the effects of TiCl 4 addition, current density, and Ti 2+ ion concentration. Under conditions of 0.6 A/cm 2 current density and 8 wt % Ti 2+ ion concentration with TiCl 4 addition, the titanium powder reaches an average particle size of 220 μm, with the oxygen content significantly reduced to 0.021 wt %, and its particle size increases significantly. The oxygen content decreases. The current efficiency during the electrolysis of TiO 2 is 54%, while the current efficiency during the secondary electrorefining process is 72%. COMSOL Multiphysics simulation shows good agreement with experimental results, highlighting the influence of current density and titanium ion concentration on cathodic deposition thickness. Compared with the traditional Kroll process, this method reduces energy consumption by approximately 30%, offering a more sustainable and energy-efficient alternative for titanium production. This study confirms the feasibility of using TiO 2 in fluoride-based molten salt systems for continuous titanium production.