PARTICLE-TO-BUBBLE ADHESION IN GAS-LIQUID SOLID SLURRIES

In gas/liquid/solid slurries, adhesion of small particles to gas bubbles is often encountered, for example, during flotation of finely divided minerals and in slurry reactors where particle-to-bubble adhesion may result in an enhanced gas absorption rate (Wimmers, 1987; Lindner, 1988). The adhesion of small particles to gas bubbles in water is studied with a modified bubble pick-up method. The extent of the particle-to-bubble adhesion is revealed in the angle alpha-max, by which the gas-bubble surface is covered by adhering particles under static conditions. It is shown that alpha-max depends on the modified Eotvos number, the ratio of the particle and bubble radii, and the effective contact angle theta-E. It is also found that theta-E is affected by the curvature of the three-phase contact ring and by the type of the gas. A "particle-to-bubble adhesion" model, indicated by PBA model, based on a balance of forces under static conditions, is developed to calculate the value of theta-E from the measured values of alpha-max. The measured values of cos(theta-E) appeared to be a linear function of the curvature 1/r of the three-phase contact ring which is in accordance with the extended Young-Dupre equation.