Modeling of inclusion removal in a tundish by gas bubbling

Inclusion removal from liquid steel by attachment to rising gas bubbles has been reviewed. A mathematical model of inclusion removal by gas bubbling in a tundish has been developed and it is found that minimization of bubble size is critical to enhance removal. However, small bubble formation in a tundish may be problematic as bubble size is controlled by high contact angles between liquid metal and bubble orifice materials. A physical modeling technique has been developed to simulate inclusion removal by tundish bubbling. The influence of a floating particle sink, a flow pattern modifying impact pad, and a bubbler, on particle separation was examined. The influence of gas flow rate, tundish residence time, particle size and bubble size was also examined. Physical modeling confirms that particle separation by gas bubbling in a tundish can be efficient at enhancing inclusion removal. It was also confirmed that relatively small bubbles (<1mm in diameter) are required for maximum separation efficiency.