Influence of MgO/Al 2 O 3 Ratio on Viscosity of Blast Furnace Slag With High Al 2 O 3 Content

The viscosity of SiO 2 −CaO−MgO−Al 2 O 3 −TiO 2 −FeO blast furnace (BF) slag system with high Al 2 O 3 content is studied by using a rotating cylinder viscometer. The effect of the MgO/Al 2 O 3 ratio on the viscosity, the stability, and break point temperature of BF slag are investigated. As a result, an increase in the Al 2 O 3 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 Al 2 O 3 content results in an increase in viscosity at a fixed temperature. The MgO/Al 2 O 3 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/Al 2 O 3 ratio can obviously improve the stability and the fluidity of the slag, and the suitable value of the MgO/Al 2 O 3 ratio decrease with increasing the Al 2 O 3 content in the BF slag. In order to maintain a good stability and fluidity of the slag, the Al 2 O 3 content in the slag should be 18% not exceed 19% and the ration of MgO/Al 2 O 3 in a range of 0.6–0.7.