Computational studies of gas-liquid-solid flows in froth flotation*

Froth flotation, where air bubbles are used to separate hydrophobic and hydrophilic particles in a slurry, is examined using fully resolved simulation. As bubbles rise through the suspension, hydrophobic particles are captured and brought to the top while the hydrophilic ones remain in the water. The Navier-Stokes equations are solved using a structured staggered grid and a finite volume method. The bubbles are followed using a front-tracking method and solid particles are treated as rigid immersed objects of different densities with zero deformation gradient. The Generalized Navier Boundary Condition (GNBC) models the contact line where particles stick to bubbles. We show results for a single bubble and several bubbles moving through fluid containing solid particles and examine the effects of various governing parameters, such as bubble deformability and the volume fraction of solids particles on the capture rate of hydrophobic particles by bubbles. Preliminary results for the formation of particle-laden foam at the free surface are also shown.