Mixing Time and Liquid Circulation Rate in Steelmaking Ladles with Vertical Gas Injection

Abstract

Flow and concentration fields in bench scale gas-injected molten steel baths were numerically studied to investigate dependency of flow structure and mixing characteristics on bath aspect ratio and gas injection rate. The problem was formulated as a two-phase flow on the basis of Eulerian approach for both gas and liquid phase transports. The effects of vessel aspect ratio and gas injection rate on mixing efficiency were characterized from the predicted time evolution of a tracer distribution in the melt and also from the liquid circulation rate. Results demonstrated that both vessel aspect ratio and gas injection rate play crucial roles on flow structure in the bath and hence on the mixing efficiency. It was observed that there is an optimum vessel aspect ratio (1.5) for minimum mixing time for the systems considered. There also exists an optimum gas injection rate for maximum mixing intensity (minimum mixing time) in a given system.