Effect of CaO/SiO2 and Fe/SiO2 Ratios on the Viscosity at 1300°C of Partly Crystallized Silicate Slags

Abstract The present study reports an experimental investigation of the effects of CaO/SiO2 mass ratio (0.4 to 1.2) and Fe/SiO2 ratio (1.26 and 1.7) on viscosity of the heterogeneous system of the CaO–SiO2–FeO–Fe2O3–PbO–MgO–ZnO–S slag at 1300°C. The viscosity was measured using rotating cylindrical viscometer, and structure of quenched slags was studied by X-ray diffraction and SEM-EDS analysis. It was found that the viscosity of the slurry decreased with an increase in CaO/SiO2 ratio and increased with an increase in Fe/SiO2 ratio. The sulphur content in the slag decreases the FeO/Fe2O3 ratio in the liquid slag and consequently increases the viscosity. The FactSage thermodynamic software is utilized for the phase equilibrium and viscosity predictions. The effect of solid fractions in slag phase on the viscosity is calculated using the Einstein–Roscoe equation. Calculations show that an increase in solid fractions increases the viscosity of the slag phase.