Electro-deoxidation behavior of Ca4Ti3O10 in molten CaCl2-NaCl

Ca4Ti3O10 is one of the important minerals enriched by titanium-containing blast furnace slag. The electro-deoxidation behavior of Ca4Ti3O10 was investigated, and titanium metal was successfully prepared in molten CaCl2-NaCl by the FFC Cambridge process. Firstly, the band structure and state density of Ca4Ti3O10 were calculated by the first principle, and the bond-breaking trend was analyzed. Then, the reduction process of Ca4Ti3O10 and the preparation mechanism of titanium were carried out by electrochemical methods. Finally, constant voltage electrolysis experiments were conducted at 900 °C and a voltage of 3.2 V for different durations. The electrolytic products were characterized using XRD, SEM-EDS, and XPS. The results revealed that the reduction process of Ca4Ti3O10 proceeded as follows: Ti4+→Ti3+→Ti2+→Ti+→Ti. The deoxidation path of the product after constant voltage electrolysis was observed as Ca4Ti3O10 → TiO2 → CaTiO3→ TiO2→ Ti2O3 → TiO → Ti2O → Ti. The whole deoxidation process can be divided into three stages: (I) the Ti-Ca bond in Ca4Ti3O10 is broken to form CaTiO3 and TiO2; (II) CaTiO3 and TiO2 are reduced from the surface of the cathode sheet inward to form a Ti-O solid solution; (Ⅲ) Ti-O solid solution is further deoxidized to form Ti metal. This method provides a theoretical basis for the subsequent electrolysis of titanium-rich slag, thereby contributing to developing a more sustainable and efficient method for extracting titanium from enriched titanium slag.