Effect of FeO Content on Viscosity, Density, and Network Depolymerization Mechanisms in CaO–SiO2–FeO–MgO–Al2O3 Slag

With the rapid advancement of short-process steelmaking technology and the demand for low-carbon emissions, electric arc furnace (EAF) has increasingly become a critical pathway in global steel production. This study systematically investigates the structure–property relationships and compositional regulation mechanisms of CaO–SiO 2 –FeO–MgO–Al 2 O 3 slag, focusing on the effects of high FeO content between 21 and 30 wt pct on viscosity, density, and microstructure. The viscosity and density of the homogeneous slags in the range between 1773 K and 1873 K were measured using the rotating cylinder and Archimedes methods, respectively. The short-range structural characteristics of slag systems with different FeO contents were analyzed by molecular dynamics simulations. The results indicate that as the FeO content increases, the liquidus temperature, viscosity, viscous flow activation energy, and the molar volume decrease accordingly, while the density increases. FeO promotes depolymerization of the aluminosilicate network, leading to an increase in the proportion of non-bridging oxygen and free oxygen and a decrease in bridging oxygen content. The results obtain the correlations between FeO content, network depolymerization, and changes in flow properties, providing a theoretical basis for slag composition optimization and foaming slag control in EAF operations.