Kinetic and thermodynamic calculations of reaction involving high aluminum low manganese steels and medium SiO2 medium Al2O3 mold fluxes with different initial aluminum contents

Steel-flux reactions involving the high aluminum (0.75-3.85 wt.% Al) low manganese (2.2 wt.% Mn) steel and the 18 wt.% SiO2-18 wt.% Al2O3 mold flux were investigated. The results indicated that the reaction rate increased when the initial aluminum content increased from 0.76 to 3.85 wt.%. Utilizing the two-film theory, a steel-flux reaction kinetic model controlled by mass transfer was established, which considered the influence of the initial composition on the density of liquid steel and flux. The mass transfer of aluminum in the steel phase was the reaction rate-determining step. It was confirmed that the mass transfer coefficient of Al was 1.87 x 10-4. The predicted results of the kinetic model were consistent and reliable with the experimental results. Thermodynamic equilibrium calculation was performed using FactSage 8.2, which was compared with the steel and flux final composition after 30 min. The content of initial aluminum in the liquid steel played a critical role in the SiO2 equilibrium content of the mold flux. In addition, the steel-flux reaction between [Al] and (SiO2) occurred with the initial SiO2 content in the mold flux lower than 3 wt.%.