Effect of High Mass Ratio of CaO to Al2O3 on Properties of Slag Containing 10% SiO2

Abstract

In this study, the viscometer is used to evaluate the viscosity of slag containing 10% SiO2 with varying CaO/Al2O3 ratios. When CaO/Al2O3 ratio increases in the 3.00–4.00 range, the viscosity exhibits a non‐monotonic behavior characterized by an initial decrease followed by an increase, with a minimum value of 0.046 Pa·s observed at 1673 K. The slag with a CaO/Al2O3 ratio above 3.00 has relatively low and stable viscosity within the range of 1373–1673 K, which is beneficial for slab quality of high‐aluminum steel. X‐ray diffraction and Raman spectroscopy are used to better understand the viscosity evolution of slag containing 10% SiO2. A higher CaO/Al2O3 ratio depolymerizes network structures due to the breaking effect of free oxygen O2−. Upon surpassing a CaO/Al2O3 ratio of 3.50, the transformation of the crystallization phase occurs from CaO·SiO2 to 2CaO·SiO2. Additionally, a higher CaO/Al2O3 ratio promotes the precipitation of the 11CaO·7Al2O3·CaF2 crystal in the slag.