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 mm and with velocities ranging from their terminal velocities to 0.3 m · s Ϫ1 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 Al 2 O 3 , MgO, ZrO 2 and MgAl 2 O 4 . 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 mm particle, in the slags/inclusions investigated a correlation between slag viscosity, h

The dissolution of Al2O3 and MgO inclusions in synthetic CaO‐Al2O3‐MgO slags have been investigated in situ with a confocal scanning laser microscope (CSLM). The dissolution mechanisms were elucidated by using analytical‐rate expressions. A set of parameters is introduced to distinguish between reaction control and diffusion control of the dissolution process. It was found that whereas Al2O3 inclusion dissolution rates are limited by diffusion, MgO dissolution appears to be limited by surface reaction. For both Al2O3 and MgO, the dissolution rate and the apparent activation energy increased when the slag composition was slightly shifted away from the saturation limit of the dissolving species in the phase diagrams.

Non-metallic inclusions composed of ZrO 2 , Al 2 O 3 , MgO and MgAl 2 O 4 are associated with problems during the continuous casting of steels and so it is desirable that such particles dissolve completely if they appear in the slag. The dissolution behaviour of particles of these oxides in a fluorine-free slag containing 1.5 wt% B 2 O 3 , was studied in situ using Confocal Scanning Laser Microscopy (CSLM). The effects of particle type, initial size, and slag temperature were investigated. Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) was performed to chemically analyze quenched samples, in order to identify any surface reaction or diffusion layers formed. Analytical prediction models were compared to the experimental data to relate the kinetics to possible rate-limiting steps. Thermodynamic solubility limits for use in the model were determined using commercial CALPHAD based software. The dissolution rates of Al 2 O 3 , MgO and MgAl 2 O 4 were found to be comparable to one another whereas the dissolution rate of ZrO 2 , is four times slower. The surface reaction appears to be controlling the rate of dissolution, with the activation energy for ZrO 2 being 128.8 kJ/mol and for MgAl 2 O 4 being 77.8 kJ/mol. This implies that the removal of ZrO 2 particles by dissolution in this type of slag is not feasible for the typical residence times expected, and strategies that prevent the incorporation of these particles should be used.