2019 Volume 59 Issue 2 Pages 209-215
It is commonly believed that the solid oxides, like aluminum inclusions, were easily removed by bubbles because of their poor wettability with molten steel. However the liquid oxides like ladle slags were hard to remove because of their good wettability. The purpose of this study was to reveal the removal rate coefficient of the hydrophilic particles, which simulated liquid oxides in molten steel, in bubbly flows. The water model experiments were carried out. The air was injected into water-particles mixtures in a rectangular tank and the amount of particles included in the mixture overflowed from the tank was measured.The experiments confirmed that bubbles have abilities to bring hydrophilic particles upward even though the particles do not adhere to the bubble interfaces. The hydrophilic particles are entrained into the bubble wake at a certain probability and dragged upward while riding on the liquid flow in the wake. The removal rate coefficient per a bubble increases with the bubble diameter whereas the increase in the number of bubbles deteriorates the efficiency due to the reduction of the wake volume which is effective for particle transportation.