Influence of bottom bubbling condition on metal emulsion formation in lead-salt system

In the steelmaking process, the reaction rate can be enhanced by increasing the interfacial area and an effective method is to emulsify the metal into the slag phase. This phenomenon is called as metal emulsion. An experimental method for investigating the formation of a metal emulsion was established using the Pb and KCl-LiCl-NaCl system, and the influence of the bottom bubbling condition on the formation of the metal emulsions was clarified. More than 1000 metal droplets were observed in 1 g of molten salt. The total weight and total surface area of the metal droplets increased with bubbling time and reached a steady state. Both values increased with gas flow rate until 300-500 mL/min, and subsequently both values gradually decreased and the local maximums were observed. Two modes of droplet formation were observed by high-speed camera; mode A in which a bubble dome with a metal film formed first and metal droplets formed when the bubble became detached from the interface, and mode B in which a metal column formed after the bubble become detached from the interface. The frequency of droplet formation in mode A showed the local maximum behavior at a gas flow rate of 300-500 mL/min.