Modelling of alloy mixing into steel - The influence of porous plug placement in the ladle bottom on the mixing of alloys into steel in a gas-stirredladle. A comparison made by numerical simulation

Gas stirring of steel in the ladle is widely used in metallurgical industri es to homogenise chemical composition and temperature, enhance reaction rat es, etc. This study focused on the homogenisation, i.e., the mixing of allo y additions and steel during gas stirring. More specifically, the influence of porous plug location on alloy mixing into steel was studied theoretical ly. Flow fields were calculated and presented for simultaneous stirring wit h 2 porous plugs in 4 different arrangements. The alloy mixing into steel i n the ladle with these different arrangements was studied with 2 different alloy addition methods. In the 1st method, the alloy was added in a batch a t the beginning of the stirring. In the 2nd method, the alloy was added con tinuously throughout the stirring. When comparing the calculated results fo r the 4 different pairs of porous plug placements, it was found that centri c stirring and centric addition rendered the best average mixing and also t he least likelihood for "dead rooms" to develop. However, the combination o f centric stirring and addition was found to be extremely sensitive to smal l variations in alloying position. It was therefore concluded that for stee lmaking, the best of the studied alternatives is using 2 porous plugs place d such that their respective radii form an angle of 60 degrees. Verificatio n of calculated steel velocities was done with experimental data taken from a previous publication.