Effect of Iron Redox Equilibrium on the Foaming Behavior of MgO-Saturated Slags

In this study, the foaming index of CaO-SiO₂-Fe_tO and CaO-SiO₂-Fe_tO-Al₂O₃ slags saturated with MgO was measured to understand the relationship between their foaming behavior and physical properties. The foaming index of MgO-saturated slags increases with the Fe_tO content due to the redox equilibrium of Fe_tO. Experimental results indicated that MgO-saturated slag has relatively high ferric ion concentration, and the foaming index increases due to the effect of ferric ion. Therefore, the foaming behavior of MgO-saturated slag is more reasonably explained by considering the effect of ferric ion on the estimation of slag properties such as viscosity, surface tension, and density. Specifically, the estimation of slag viscosity was additionally verified by NBO/T, and this is experimentally obtained through Raman spectroscopy.