Effect of Elasticity and Surface Forces on the Stability of Foams and Lamellae Films in the Presence of Flotation Frothers
The stability of foams and froth plays an important role in flotation, in which small amounts of relatively weak non-ionic surfactants (frothers) are used to produce air bubbles and foams. In the present work, factors affecting the stability of the foams produced in the presence of common frothers, such as n-pentanol, n-octanol, methyl isobutyl carbinol (MIBC), and polypropylene glycol (PPG), have been studied. We used the thin film pressure balance (TFPB) technique of Scheludko-Exerowa type to measure the equilibrium film thicknesses. The results were used to determine the contributions from the various surface forces to the disjoining pressures in the thin lamellae (foam) films formed between air bubbles. In addition, we used a model developed by Wang and Yoon (Colloids and Surfaces A: Physicochem. Eng. Aspects, 2006) to calculate the elasticities of the lamellae films at the critical thicknesses at which films rupture. The surface forces and elasticity data were then compared with the foam stabilities in the presence of the various flotation frothers. It was found that foam stabilities are controlled by both film elasticity and surface forces, the relative contributions of which change with frother type and concentration. In general, surface forces play a more important role at relatively low frother concentrations, while elasticity plays a more important role at higher concentrations. At the frother additions usually employed in the mining industry,MIBC relies on surface forces while PPG-400 relies on film elasticity in producing stable foams.The former is capable of dampening the hydrophobic force, which is a major attractive force destabilizing lamellae films, while the latter is capable of reducing surface tensions at low concentrations.
Gibbs elasticity Surface force Frother Froth stability MIBC PPG Hydrophobic force
L. G. Wang R. H. Yoon
School of Engineering, The University of Queensland, Brisbane, Australia Center for Advanced Separation Technologies, Virginia Polytechnic Institute and State University, Bl
国际会议
XXIV International Mineral Processing Congress(第24届国际矿物加工大会)
北京
英文
1000-1007
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）