Investigation on the Viscosity and Fluidity of FeO-CaO-SiO2 Ternary Primary Slag in Cohesive Zone of Blast Furnace

The permeability of cohesive zone plays an important role in the stable operation and production efficiency of blast furnace. Fluidity of the primary slag in the cohesive zone is an important factor affecting the permeability and is usually characterized by the so-called fluidity index. In order to describe the relationship between the viscosity and the fluidity index of the FeO-CaO-SiO2 ternary slag system (similar to the primary slag) generated by sinter, the fluidity and viscosity of FeO-CaO-SiO2 ternary slag system was studied in this paper. It includes testing the fluidity under different temperatures and different compositions, calculating the viscosity of FeO-CaO-SiO2 ternary slag system through the solid–liquid coexistence-phase viscosity model, and coupling the relationship between fluidity index and viscosity. The results show the following: (1) For the FeO-CaO-SiO2 ternary slag system, when the temperature is constant, the fluidity index of primary slag in non-three-phase region increases with the increase in w (FeO), while that in three-phase region decreases with the increase in w (FeO). (2) The Kondratiev model and the Batchelor model were jointly employed to calculate the primary slag viscosity in the cohesive zone. (3) In FeO-CaO-SiO2 ternary slag system, there is an approximate power function correlation between the solid–liquid coexistence-phase viscosity and the fluidity index. The research content and results of this paper have a certain theoretical guiding value for further research on more complex cohesive zone slag system and enhanced blast furnace smelting.