Highly Efficient Titanium Powder Production via Electro-Reduction of TiO₂ in Commercial CaCl₂ Molten Salt: Mechanism and Optimization Investigation

Novel electrolytic techniques for titanium extraction have been introduced to enhance the utilization of titanium. Among these methods, the Fray–Farthing–Chen (FFC) Cambridge process is considered a promising approach for titanium production. However, the current efficiency of the FFC Cambridge process remains insufficient for commercialization. This study explores the electrochemical reduction of titanium dioxide (TiO₂) in food-grade calcium chloride (CaCl₂) molten salt electrolyte using the FFC Cambridge process. TiO₂ granules were utilized as the cathode material to investigate the reduction path. The formation of titanium sub-oxides and calcium titanates was meticulously examined under various conditions. The reduction route was further analyzed thermodynamically by plotting the predominance diagram of titanium oxides in molten CaCl₂. Full metallization of the samples was achieved within 4 h under a constant voltage of 3.2 V. The study delves into the impact of salt composition (CaCl₂ + x mol.% calcium oxide) and cathode preform on optimizing titanium extraction. TiO₂ powder was employed as the precursor to explore the feasibility of powder reduction for scale-up purposes and reducing oxide preparation costs. The results demonstrated the rapid reduction of TiO₂ powder and the synthesis of titanium with a low oxygen content of 1900 ppm. A remarkable current efficiency of 76.6% and low energy consumption of 9.34 kWh/kgTi were achieved, showcasing promising results for an electrolytic process.