Effect of TiO2 on the Viscosity and Structure of Mineral Wool Melt from Blast Furnace Slag

The effect of TiO2 on the viscous behaviours of mineral wool melts containing CaO−SiO2−Al2O3−MgO-TiO2 were studied at acidity coefficient Mk in the range of 1.0–1.6 and TiO2 content in the range of 0–6wt%. Based on the experimental data, the critical temperature and activation energy were calculated to analyse the changes in viscosity flow. The morphology and phase of slag were clarified by scanning electric microscopy with energy dispersive spectroscopy and X-Ray diffraction. Fourier transformation infrared and Raman spectra were used to obtain information about the variations in melt structure. The results showed that the viscosity decreased with increasing TiO2 content. The critical temperature (Tcr) was 1537–1645K, and it was relatively stable when the acidity coefficient Mk is 1.3. The activation energy decreased from 182.27, 178.48, 162.75 kJ/mol to 146.67, 139.28, 127.64 kJ/mol with increasing acidity coefficient Mk, respectively. With increasing TiO2 content, the fraction of main crystal phases (CaSiO3) decrease and form perovskite (CaTiO3). In addition, relationships are found to exist between the viscosity and structure of melt. The formation of Ti-O or O-Ti-O bonds weakens the stability of molten slag, and the number of bridging oxygen decreases from 1.85 to 0.65.