A Mathematical Modeling Study of Bubble Formations in a Molten Steel Bath

The bubble formation during gas injection into liquids was studied using a water model and a three-dimensional numerical model. In the experiment, a high-speed camera was used to record the bubble formation processes. Nozzle diameters of 0.5, 1, and 2 mm were investigated under both wetting and non-wetting conditions. The bubble sizes and formation frequencies as well as the bubbling regimes were identified for each nozzle size and for different wettabilities. The results show that the upper limits of the bubbling regime are 7.35, 12.05, and 15.22 L/h under wetting conditions for the 0.5, 1, and 2 mm nozzle diameters, respectively. Meanwhile, the limits are 12.66, 13.64, and 15.33 L/h for the non-wetting conditions. In the numerical model, the volume-of-fluid method was used to track the interface between the gas and liquid. The simulation results were compared with the experimental observations in the air-water system. The comparisons show a satisfactory good agreement between the two methods. The mathematical model was then applied to simulate the argon-steel system. Simulation results show that the effect of nozzle size is insignificant for the current studied metallurgical conditions. The upper limits of the bubbling regime are approximately 60 and 80 L/h for a 2-mm nozzle for the wetting and non-wetting conditions, respectively. In addition, a poor wettability leads to a bigger bubble and a lower frequency compared with a good wettability, for the same gas flow rate. (C) The Minerals, Metals & Materials Society and ASM International 2015