Prediction of the optimum bubble size for inclusion removal from molten steel by flotation

Abstract

A mathematical model has been developed to determine the optimum bubble size for the removal of inclusions from molten metals by flotation. The probability of collision between a bubble and an inclusion, PC, and the probability of adhesion of an inclusion to a bubble by sliding, PA, are defined to describe the efficiency of inclusion attachment to a bubble. The results show that small bubbles have a high PC, while small inclusions have a high PA and low PC. By considering the overall probability, P(=PC × PA), and the floating time of the bubble, the model suggests that the optimum bubble sizes for the removal from steel of alumina inclusions less than 50μm in size are in the range of 0.5 to 2mm in diameter.