Metal emulsion in Sn alloy/oxide system by bottom gas injection

A metal emulsion is formed by the passage of gas bubbles through the interface between the metal phase and the slag phase in the steelmaking process. Emulsified metal droplets have great potential to improve the chemical reaction efficiency during motion in bulk slag. Several studies have focused on the formation mechanism of metal droplets and on the influence of the physical properties of the system on this mechanism. In this study, Sn alloy and sodium tetraborate were used to simulate molten steel and slag, respectively. Gas bubbles were introduced from the bottom of a molten metal bath at various gas flow rates. Slag containing metal droplets at the center of the slag phase was sampled, and the metal droplets were extracted by the dissolution of the oxide in a solvent. The number and diameter of the droplets were measured using a digital microscope. Under the same experimental conditions, the number of metal droplets in the oxide system was smaller but their size was larger than those in a previously investigated Sn alloy/chloride system. In both the systems, the total mass of metal droplets formed by a single bubble increased with an increase in the volume of the gas bubble, and when the volume of the gas bubble was small, the total mass of droplets in the oxide system was smaller than that in the chloride system. The sedimentation rate and coefficient in the oxide system were lower than those in the chloride system.