Settling of Particle in Foaming Slag

During steel-manufacturing, molten slag is foamed through gas injection and gas generation reactions. However, molten iron droplets are trapped in the slag. The settling velocity of an iron droplet in the foaming slag is important because the residence time of an iron droplet in the slag is used to directly calculate the settling velocity. Previous studies have shown that the rate of settling velocity is lower than that observed in regular non-foaming slag. However, this has not been quantitatively determined. This study measured the settling velocities of particles through a foaming glycerin-water solution. A dimensionless correlation equation for particle settling velocity in the formed liquid was proposed by conducting a dimensional analysis of the experimental data. Using the obtained equation, the settling velocity of iron particles in the foaming slag was predicted. The settling velocity of iron particles was significantly affected by the volume fraction of the gas phase in the foaming slag. A threshold for the velocity was observed; the velocity of particles below this threshold was zero.