Effect of superheat degree and MnO on structural characteristics of CaO-SiO2-TiO2-based blast furnace slags

High-temperature equilibration experiments were carried out to investigate the liquidus temperature of CaO-SiO2-TiO2-MnO slags, and the addition of MnO into the slag could decrease the liquidus temperature. Furthermore, Raman spectra of CaO-SiO2-TiO2–1wt%MnO quenched slags under various superheat degrees and slags with different MnO content were also studied to uncover the slag structure characteristics. Higher superheat degree mainly simplified the complicated structural units of CaO-SiO2-TiO2–1wt%MnO slags by promoting to form simpler silicate units. Increasing the MnO content in the slag could provide more free oxygen ions to break the Si-O bond of polymerized silicate units and weaken the silicate network stability. The relationship between slag viscosity and nBO was fitted, and the viscosity (lnη) linearly increased with increasing the nBO. To some extent, the fitted expression could reflect the relationships of the slag viscosity and structure.