Effect of Al₂O₃, MgO, and CaO/SiO₂ on Viscosity of High Alumina Blast Furnace Slag

The effects of Al₂O₃, MgO, and binary basicity on the viscosity of high alumina blast furnace slag are studied systematically at the temperatures of 1773 K and below using the orthogonal experimental design method. The results show that, at fixed binary basicity (CaO/SiO₂) between 1.1 and 1.2, higher Al₂O₃ content increase the slag viscosity due to the polymerization of the aluminate structures. At fixed Al₂O₃ content between 15 and 20%, increasing the CaO/SiO₂ from 1.1 to 1.2 lead to lower viscosity due to the depolymerization of the aluminate structures. At fixed MgO between 9 and 11%, both increasing Al₂O₃ content and CaO/SiO₂ can make the melting temperature increase. In addition, the viscosity data of high alumina blast furnace slag was in accordance with the estimated values of viscosity by Riboud model. Understanding the mechanism of Al₂O₃, MgO, and binary basicity on the viscosity of blast furnace slag can provide a promising method for optimizing its viscosity value and improving the blast furnace operation.