Effect of TiO₂ on the Phase Transformation and Microstructure Evolution of Ti-Containing Melting Slag in the Alkali Fusion Process

The effect of TiO₂ on the phase transformation and microstructure evolution of Ti-containing melting slag in the alkali fusion process has been investigated. The results showed that, after alkali fusion roasting, the original phase of Ti-containing melting slag was completely decomposed by molten NaOH, and that the alkali fusion slag mainly included Na₂TiO₃ and NaMO₂ (M = Ti, Mg). With increasing TiO₂ content, NaMO₂ and Na₂TiO₃ converted to each other, and the content of sodium magnesium silicate also changed with the “in and out” of Mg. The contents of NaAlO₂ and silicates were not significantly affected by the TiO₂ content, while the microstructure of the melting slag corroded by molten NaOH changed greatly. With increasing TiO₂ content, the microstructure of the alkali fusion slag transformed from an uneven grain size to a uniform grain size, and ultimately a compact structure.