Gas-liquid slip velocity determination in co-current column flotation

The motion of air and water is characterised in a downflow co-current column reactor. The velocity of the bubble swarm relative to that of the bulk water is determined using a new approach for the computation of the slip velocity in a CFD simulation using a modified drift flux model and incorporating the data obtained from the CFD modeling. The validity of the numerical model is confirmed by comparing the simulation results with those of experimental. The average slip velocity is found to be approximately 3.3 cm/s in the down-comer co-current column, which is lower than those prevailing in counter-current columns. It is concluded that in a bubbly flow regime lower slip velocity improves the bubble particle collection efficiency.