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 1773K 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.