Fundamentals of inclusion removal from liquid steel by attachment to rising bubbles

This paper is a review of the fundamentals of inclusion removal from liquid steel by attachment to the rising bubbles. Based on the water/particle study carried out in the field of mineral processing, silica inclusion and argon gas are taken as the bubble/inclusion phases. The mechanism of bubble/inclusion interaction, bubble size and rising velocity, liquid film formation and rupture between the bubble and inclusion, collision time, film drainage time, sliding time, collision and adhesion probabilities are discussed. A simple mathematical model of inclusion removal by attachment to the rising bubbles is described, and the effects of gas flow rate, bubble size and time on the inclusion removal are discussed. Based on the results of the models, it is concluded that the optimum bubble diameter for the inclusion removal is 1 to 5 mm. The shroud from the ladle to the continuous casting tundish is a good place to inject gas to remove inclusions by attachment to the rising bubbles.