Prediction of van der Waals interaction in bubble-particle attachment in flotation

van der Waals interaction is one component of the surface force interaction s, which control bubble-particle attachment in flotation. In this paper, ap proximations to Lifshitz theory are developed to estimate the van der Waals interaction energy vs. separation distance between a bubble and a particle . The dielectric spectrum of the mineral particles is approximately represe nted using a three-parameter model involving the refractive index and the d ielectric constant of minerals, The effects on the van der Waals interactio n of electromagnetic retardation and electrolyte screening are estimated, T he approximations yield simple predictions for the Hamaker constant and the Hamaker function, which are convenient for the modelling of the micro-proc esses of the bubble-particle attachment. The approximate predictions agree with the results computed from rigorous Lifshitz theory using the complete dielectric spectra. The analysis shows that van der Waals interaction in th e bubble-particle attachment is affected by electromagnetic retardation (th e dispersion interaction only) and electrolytes (the dipolar interactions o nly), and can be predicted using the refractive index of mineral particles. (C) 2001 Elsevier Science B.V. All rights reserved.