Effect of Temperature, FeO, and Carbonaceous Materials Including Spent Tires on the Slag Foaming Behavior in EAF Slags

Electric arc furnace (EAF) steelmaking offers a more sustainable alternative to conventional blast furnace-basic oxygen furnace processes, with significant potential to reduce CO₂ emissions. In EAF operations, slag foaming plays a critical role by shielding the electric arc, minimizing refractory erosion, and enhancing thermal efficiency. This study investigates the in situ slag foaming behavior of commercial EAF slag through video analysis, focusing on the effects of reaction temperature, FeO content, and various carbonaceous materials, including alternative sources, such as spent tires. The results indicate that reaction temperature influences both slag fluidity and the dissolution of monoxide from the MgO crucible. While higher FeO concentrations initially promote gas generation and increase initial foaming height, excessive levels reduce foam stability due to rapid bubble rupture and lower slag viscosity. Incorporating spent tires into the carbonaceous materials leads to a higher initial foaming height, attributed to the release of volatile matter; however, it substantially decreases foam retention time. Optimizing the mixing ratio of spent tires to anthracite is, therefore, crucial for balancing gas generation with foam stability. These findings highlight the importance of controlling slag chemistry and carbonaceous material composition to improve the operational efficiency of EAFs while advancing environmental sustainability.