Study On Stability And Antifoaming Of Three-phase Foam

In this dissertation, the influence of diaspore with hydrophobicity surface on the stability of foams was studied by measuring surface tension, viscosity, zeta-potential and contact angle. At the same time, the defrothing study of three-phase foam was performed on the obverse floatation concentrates of bauxite. Main conclusion are obtained as following:The factors that influence the stability of the sodium oleate two-phase foam, are concentration of sodium oleate, pH and temperature.The stability of the sodium oleate two-phase foam is increased with the increase of sodium oleate concentration. The increase of sodium oleate concentration not only reduces the surface tension, but also enhances the strength of bubble liquid film. The stability of the sodium oleate two-phase foam is increased with the increasing of pH value. When pH<6, the stability of two-phase foam becomes poor. However, the stability of sodium oleate two-phase foam is the best when pH value is about 10. The stability of the sodium oleate two-phase foam is decreased with the increasing of temperature.The factors that influence the stability of three-phase foam, are the particle size of solid, solid concentration, hydrophobicity of particle and viscosity.The stability of three-phase foam is improved with diminishing of particle size. With the increasing of solid concentration, the stability of three-phase foam is increased; but there exists a suitable solid concentration, above this solid concentration, the stability of three-phase foam is decreased. With the improving of the hydrophobicity of diasopore, the stability of three-phase foam is increased. With the addition of diaspore below 0.01mm, the viscosity of solution is increased, the drainage speed of liquid film is decreased, these lead to the enhancing of the stability of three-phase foam.There are two factors which can be explained for the stability destroying of sodium oleate two-phase foam: Firstly, with the addition of antifoaming agent, the viscosity is decreased, the drainage speed of liquid film is increased; secondly, the change rate of dynamic surface tension of solution is enhanced, so that the stability of foam is falling.To the stability of the three-phase foam of bauxite flotation, when the anti-foam agent is used only, the speed of defoaming is low; the speed of defoaming is increased when antifoaming agent is added with mechanicalagitation.When the antifoam agent is used only, it is hard to destroy the stability of liquid film by diffusion and adsorption; Foam is struck and stretched with mechanical agitation, the diffusion and adsorption of antifoaming agent are increased and it is easy to move to the position where foam is stretched. So the stability of foam is destroyed.