Influence of MgO/Al2O3 Ratio on Viscosity of Blast Furnace Slag With High Al2O3 Content

The viscosity of SiO2−CaO−MgO−Al2O3−TiO2−FeO blast furnace (BF) slag system with high Al2O3 content is studied by using a rotating cylinder viscometer. The effect of the MgO/Al2O3 ratio on the viscosity, the stability, and break point temperature of BF slag are investigated. As a result, an increase in the Al2O3 content and a decrease of temperature tended to make the stability of slag become worse gradually due to an increase in the degree of the polymerization of the slag. In addition, increasing Al2O3 content results in an increase in viscosity at a fixed temperature. The MgO/Al2O3 ratio of the slag have obvious effect on the influence of the temperature of the BF slag on viscosity of the slag; the proper use of the MgO/Al2O3 ratio can obviously improve the stability and the fluidity of the slag, and the suitable value of the MgO/Al2O3 ratio decrease with increasing the Al2O3 content in the BF slag. In order to maintain a good stability and fluidity of the slag, the Al2O3 content in the slag should be 18% not exceed 19% and the ration of MgO/Al2O3 in a range of 0.6–0.7.