The Effect of Substituting FeO with CaO on the Rheological and Surface Properties of Silicate Melts

A comprehensive understanding of the structural impact of composition is crucial in designing converter slag to optimize its rheological and surface properties during the smelting process. In this study, glassy CaO-SiO2-FexO samples with varying CaO/FexO ratios were prepared to simulate the slag in the initial stage of converter melting. The viscosity and surface tension of the slag at 1300-1600 degrees C were measured, and the microscopic essence of physical properties was further analyzed using Raman spectroscopy technology. The findings reveal that as CaO replaces FeO, [SiO4]-tetrahedra gradually depolymerize from Q4(Si) to Q0(Si), while [FeO6]-octahedra gradually transform into [FeO4]-tetrahedra, resulting in a decrease in the degree of polymerization of the slag. The slag with a lower degree of polymerization exhibits reduced activation energy of viscous flow and increased surface tension. Therefore, it is of great significance to appropriately control the CaO/FexO ratio in the early stage of smelting to improve the rheological and surface properties of the slag.