Effect of the Slag Composition on the Sustainable Silicothermic Synthesis Process of Titanium Silicides

TiSi2 and Ti5Si3 were synthesized through a simple and cost-effective process, providing a sustainable way to recycle titanium oxide and silicon wastes from industry. The reaction process was investigated at 1500 °C under various slag/silicon ratios and slag compositions. TiSi2 was synthesized successfully under all experimental conditions, with nearly complete extraction of titanium oxide from the slag within 5 h under optimized conditions. TiSi2 initially formed at the slag/silicon interface, followed by the formation of Ti5Si3 as TiSi2 droplets fell through the slag. The production rate of TiSi2 was higher than that of Ti5Si3. Kinetic analysis showed that the reaction rate constant ranged from 1.2 × 10−5 to 4.3 × 10−4 s−1. Viscosity and basicity were not the limiting factors of the kinetics in this work. The amount of TiO2 in the slag significantly influenced the reaction process, with slag containing less than 30 mol% TiO2 identified as optimal for efficient titanium extraction and a high synthesis rate.