Investigation of mixing and slag layer behaviours in the RH degasser with bottom gas injection by using the VOF–DPM coupled model

The mixing time of molten steel has a decisive impact on the refining efficiency during the RH (Rheinsahl–Heraeus) degassing process. In the present work, a coupled volume of fluid method−discrete phase model has been developed to investigate the effect of bottom injection on mixing and slag layer behaviours in the RH degasser. The fluid flow, mixing characteristic, and the formation of slag eye in the RH degasser with bottom injection are well revealed. Numerical results show that X = −0.75 m (under the up-snorkel) is the optimal injection location to obtain a shortest mixing time, as well as avoid the formation of slag eye in the RH degasser. At the same time, the result of industrial trial shows that the decarburisation efficiency can be accelerated remarkably when the bottom injection is located at X = −0.75 m.