Exact and Approximate Expressions for Bubble-Particle Collision.
The flotation microprocess of collision is investigated and an exact expression for the probability of collision (Pc) is developed based on the intermediate flow of Yoon and Luttrell (1). This expression for Pc only assumes that the bubble and particle are spherical and that the particle radius is less than the bubble radius (i.e., Rp < RB). In addition to removing the requirement that Rp << RB, the influence of a particle settling velocity is also included in the model development. The expression for Pc is shown to be a function of three dimensionless groups: (i) the magnitude of the dimensionless particle settling velocity, ||G ||; (ii) the bubble Reynolds number, ReB; and (iii) the ratio of particle to bubble radius, Rp/RB. The probability of collision model is compared to available experimental data and good agreement is shown. A parametric study is also completed for 0 </= ||G || </= 1, 0 </= ReB </= 500, and 0.001 </= Rp/RB < 1. In general, Pc is independent of ReB when Rp/RB less, similar 0.03, the particle settling velocity is important for small values of Rp/RB, and Rp/RB dominates as Rp/RB --> 1. Copyright 1999 Academic Press.
Heindel
TJ
Engineering Division, Institute of Paper Science and Technology, 500 10th St., N.W., Atlanta, Georgia, 30318
Bloom
F