The ability of slags to absorb solid oxide inclusions

The capture rate of solid oxide-inclusion particles from molten steel by molten slag depends on the rate of steel film drainage (which occurs at certain particle velocities), interfacial separation, and dissolution into the slag. In this study the capture of common oxide inclusions of sizes 2.5-200 mu m and with velocities ranging from their terminal velocities to 0.3 m (.) s(-1) approaching the interface between molten iron and slags with chemistries corresponding to ladle, tundish and mold slags are investigated. Calculations, based on a model available in literature, show that film drainage (when applicable) is rapid enough to be ignored. A sensitivity analysis based on the slag properties show that the interfacial energy between slag and inclusion is the most pertinent property that could hinder interfacial separation. However, the interfacial tension needed to achieve this has to be a minimum of 0.41 N/m which is unreasonable for the case of common oxide inclusions such as Al2O3, MgO, ZrO2 and MgAl2O4. The final step of dissolution was found based on studies with Confocal Scanning Laser Microscope experiments, to be significantly slower than the other steps. For a 100 mu m particle, in the slags/inclusions investigated a correlation between slag viscosity, eta [Pa (.) s] and super saturation, Delta C [kg (.) m(-3)] with inclusion dissolution time, tau [s] was shown to be, tau=2.04 (.) 10(-2)/(C/eta).