Consideration of the Competitive Adsorption of Oxygen and Sulfur on the Decarburization Kinetics of Fe–C Droplets in Oxidizing Slag

An experimental study was performed to understand the effect of competitive adsorption between oxygen and sulfur on the kinetics of decarburization of droplets in oxidizing slag. Experiments were conducted by varying droplet sulfur concentration and oxygen transport properties of the slag. The latter was achieved by varying the slag electrical conductivity. The results showed that for a fixed slag composition, with increasing sulfur concentration in the droplet, the kinetics of decarburization were impeded by surface poisoning. On the other hand, for a fixed sulfur concentration in the droplet, increasing the slag conductivity at constant FetO concentration accelerated the transport of oxygen in the slag and leading to increased oxygen adsorption on the droplet surface. The interplay between oxygen and sulfur adsorption appeared to control the oxygen flux into the metal. When sulfur adsorption was dominant, transport of oxygen into the droplet and subsequent decarburization were inhibited, whereas by displacing adsorbed sulfur by oxygen, appeared to create pathways for oxygen into the droplet.