Effect of process parameters on ultrasonic separation of dispersed particles in liquid

Abstract

The effects of process parameters on ultrasonic separation of dispersed particles in a liquid using a standing-plane-wave field are discussed on the basis of experimental and theoretical results. Numerical solution of the equation of motion of a fine particle in a standing-wave field indicates that the inertia term can be neglected during conventional ultrasonic separation of fine particles. Analytical solutions for the particle speed, the position at which particles are coagulated, and the minimum power for separation, have then been derived to incorporate key process parameters. Experiments are carried out to observe transitional coagulation of polystyrene particles in an aqueous sugar solution with the incidence of standing ultrasonic plane wave, in terms of the density difference as well as the acoustic energy density exerted. Experimental results agree well with the theoretical predictions. The time required for coagulating and for the separation of particles is shortened in the case that particles coalesce. © 1999 Publication Board, Japanese Journal of Applied Physics.