Study on a new molten salt for electrolytic preparation of Ti: dissolution mechanism and kinetic analysis of TiO2 in NaCl-KCl-K2TiF6

Understanding the dissolution behavior and reaction rate of TiO2 in the NaCl-KCl-K2TiF6 electrolyte system is paramount for the advancement of a novel titanium metal production process. Initially, the liquidus temperature of the electrolyte system decreases with an increase in K2TiF6 content or the addition of a small amount of TiO2. Kinetic analysis reveals that the dissolution of TiO2 in the electrolyte follows a zero-order reaction for the first 30 min, with an activation energy of 2.46 × 105 (J/mol). The saturation concentration of TiO2 is reached at 300 min, and higher reaction temperatures or increased K2TiF6 content enhance the solubility of TiO2 in the electrolyte. In addition, the regression equation Y = − 25.02096 + 1.06412x1 + 0.0362x2 among the solubility of TiO2 (Y), the ratio of fluoride to chloride in electrolyte (x1) and experimental temperature (x2) was established by multivariate regression model. The analysis indicates that TiO2 dissolves in the electrolyte system as a complex K2NaTiOF5, releasing TiOF2 gas during the reaction. Finally, characterization studies on the elemental composition, chemical state, molecular structure, and material morphology of K2NaTiOF5 complex and TiOF2 gas reveal even distribution of elements. The K2NaTiOF5 complex molecules exhibit irregularly polygonal dispersion, while TiOF2 exists as agglomerated particles. © 2024 Elsevier B.V.