Modeling on the Desulfurization of the Molten Steel During RH Process

Abstract

The present study integrated the multiphase flow of molten steel, desulfurizer dispersion, and desulfurization kinetics to explore the impact of injection amount, injection speed, and lance position on desulfurizer injection desulfurization. This investigation employed a coupled k-ε model, Volume of Fraction (VOF) model, Discrete Phase Model (DPM), user-defined scalar equation (UDS), and unreacted core desulfurization kinetic model. The sulfur content measured in the actual desulfurization process was utilized to validate the mathematical model. Most of the finer powder particles with a diameter of 3 mm tended to stay at the steel surface in the vacuum chamber, with only a fraction being carried by the steel flow into the ladle and then rising to the steel surface. As the increasing of the total desulfurizer amount, the average sulfur content in the molten steel initially increased, but then remained unchanged. However, reducing the total desulfurizer amount from 1200 to 400 kg decreased desulfurization efficiency by 13 pct while the reduction in sulfur content per unit weight of desulfurizer at 400 kg was 2.5 times greater than that achieved at 1200 kg. An increase in the injection speed of desulfurizer resulted in a decrease in average sulfur content, while reducing the injection speed from 200 to 100 kg/min decreased desulfurization efficiency by 19.66 pct. Increasing the position of the desulfurizer injection lance elevated the average sulfur content in the molten steel. Lowering the high lance position of 3.2 m to the low lance position of 2.0 m increased the desulfurization efficiency at the endpoint by 7.45 pct. Additionally, the highest average desulfurization rate increased from 0.0477 to 0.0542 ppm/s. The relationship between the sulfur content in the molten steel and the injection amount, injection speed, and injection lance position can be described by the equation \({\text{ln}}\left( {\left[ {{\text{pctS}}} \right]/{{\left[ {{\text{pctS}}} \right]}_0}} \right) = 1.841 \times {10^{ - 6}}\cdot{m_{{\text{de}}}}^{0.2}\cdot{I^{1.5}}\cdot{H^{ - 1.2}}t\) This equation holds significant practical relevance for powder injection desulfurization during the RH refining process.