Particle-bubble collision models - a review

A critical review of the various models existing in the literature for the calculation of the collision efficiency between particles and single, risin g gas bubbles is presented. Although all of these collision models predict that the collision efficiency increases with particle size, their dependenc e on the latter is different because of the various assumptions and hydrody namic conditions used in each model. Collision efficiencies of quartz parti cles with single bubbles have been obtained from experimental flotation exp eriments under conditions where the attachment and stability efficiencies w ere at, or near, unity. These collision efficiencies were then used to test various collision models. Good agreement between the experimental and calc ulated collision efficiencies was only obtained with the Generalised Suther land Equation. The differences in collision efficiencies obtained between t he various models were mainly explained in terms of, firstly, the degree of mobility of the bubble surface and, secondly, a consideration of the inert ial forces acting on the particles. (C) 2000 Elsevier Science B.V. All righ ts reserved.