Simulation research on oxygen mass transfer between steel and slag in IF steel refining process

Abstract

The effects of oxidizing slag on oxygen mass transfer and inclusions in different stages of IF (interstitial-free) steel refining were investigated by several heat simulation experiments. The results of the experiments showed that the oxidizability of slag changed considerably during different refining stages. Keeping the content of FeO in the slag within 1 wt.% would narrow the difference of slag oxidizability, stabilize the content of [Al]s in the steel, avoid secondary oxidation of molten steel by the slag, and reduce the inclusions. When the mass transfer of FeO in the slag phase was a limiting step, the secondary oxidation reaction occurred at the steel–slag interface; when the diffusion of oxygen in the molten steel was a limiting step, the secondary oxidation reaction took place inside the molten steel. The oxygen transfer rate was affected by the mass transfer coefficient of oxygen. For every 0.0001 m/s increase in mass transfer coefficient, the oxygen transfer rate increased by about 2.2 × 10−6 min−1. By changing the mass transfer coefficient, the oxygen transfer rate of the slag to the molten steel can be controlled.