The elimination of inclusions in steelmaking processes has been widely studied. The removal of inclusions by slags containing the rare earth oxide Ce2O3 are studied using an integrated numerical model. The integrated model involves the inclusion motion model, interfacial tension calculation model, surface tension calculation model of slag, and the mass action concentration model, based on ion and molecule coexistence theory. The motion behaviors of both solid Al2O3 inclusions and 50%wtAl2O3–50%wtCaO liquid inclusions of varied sizes at CaO-Ce2O3-SiO2-Al2O3(-MgO) slag systems are evaluated. The results show that it is more difficult to remove the inclusions with smaller sizes and in slag with a higher viscosity. Liquid inclusions are more difficult to remove than solid inclusions. It is found that the CaO-Ce2O3-SiO2-Al2O3-MgO refining slag shows a better ability to remove Al2O3 inclusions than that of the CaO-SiO2-Al2O3-MgO slag. The reason for this is that the addition of the rare earth oxide Ce2O3 can decrease the viscosity of slags, as well as improving the wetting effects of slags on Al2O3 inclusions. For two slags systems, the CaO-Ce2O3-SiO2-Al2O3-MgO slag system shows a better ability to remove Al2O3 inclusions than the CaO-Ce2O3-SiO2-Al2O3 slag system. The addition of 5% to 8% Ce2O3 in a CaO-SiO2-Al2O3-MgO slag is an optimized case for industrial applications.

The performance of gas blown in side walls of a single strand tundish is numerically simulated. Three cases are studied, i.e. tundish without gas blown, tundish with gas blown from the right side wall, and from the front wall. The vortex circulating flow is the main flow structure in tundish without gas blown. The gas blown from the right side wall of tundish will significantly change the flow field. The short-circuit flow that the tracer flow along the bottom of tundish to the outlet is becoming the main flow pattern. The RTD curve shows a rapid increase tendency. An anticlockwise flow near the top surface is formed. The mixing of tracer in the tundish is delayed and the dead volume fraction is increased when compared with the tundish without gas blown case. In contrast, the gas blown from the front wall of tundish will divide the tundish into two parts. The strong circulation flow in two parts is formed. Besides, the mixing of tracer is faster and the dead volume fraction is lower than that of the case without gas blown. This case may be an optimized gas blown technology in tundish.