Physical model studies on slag foaming

A physical modelling investigation has been undertaken to determine the relationship between the physico-chemical properties of the liquid phase, the gas bubble size, the gas flux, and the residence times of gas in spherical foams. The testwork was conducted in a 107 mm diameter glass column in a temperature controlled environment. The foams were generated by the injection of compressed air into solutions of distilled water and glycerol. Water glycerol solutions were used to obtain a wide range of liquid viscosities. The strongly adsorbing surfactant, sodium dodecylbenzene sulphonate, was added to the water-glycerol solutions so that the surface tensions of the solutions could also be controlled. The experimental results show that the residence times of gas bubbles in the foam increase with increasing liquid viscosity and increasing surface tension depression, and with decreasing gas bubble size. Furthermore, a transition from a foaming to a non-foaming regime was observed as the mean gas bubble diameter increased above 5 mm.