Simulation for mass transfer kinetics at slag-steel interface during high Al steel continuous casting

Abstract

A series of laboratory-scale experiments were carried out in order to elucidate the relationship between the flow field and slag-steel reaction in mold, which could provide a theoretical fundamental of for controlling the slag-steel reaction by kinetics during high alumina steel continuous casting process. The similarity of slag-steel interface mass transfer behavior between simulated experiment and actual continuous casting process was determined through theoretical derivation, and the mold water model was established. Simultaneously, a mathematical model for predicting the composition of mold slag was established according to the principle of slag-steel reaction, and the predicted results were consistent with the results of slag-steel reaction in an actual continuous casting and laboratory experiments. The effects of mold casting speed, SEN (Submerged Entry Nozzle) outlet angle and submerged depth on slag-steel reaction rate were also investigated by water model. The simulated continuous casting results reflected that the slag-steel reaction rate can be controlled by controlling the mold surface velocity and fluctuation. On the one hand, reducing the mold surface velocity could slow down the replenishment rate of “fresh” molten steel, then the concentration gradient of [Al] between the liquid-steel and slag-steel interface was decreased, leading to a slower reaction rate. On the other hand, weak surface fluctuation could reduce the slag-steel interface area, thus reducing the capacity mass transfer coefficient of interfacial mass transfer, as well as the reaction rate.