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

The effects of process parameters on ultrasonic separation of dispersed par ticles in a liquid using a standing-plane-wave field are discussed on the b asis of experimental and theoretical results. Numerical solution of the equ ation of motion of a fine particle in a standing-wave field indicates that the inertia term can he neglected during conventional ultrasonic separation of fine particles. Analytical solutions for the particle speed, the positi on 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 particle s in an aqueous sugar solution with the incidence of standing ultrasonic pl ane wave, in terms of the density difference as well as the acoustic energy density exerted. Experimental results agree well with the theoretical pred ictions. The time required for coagulating and for the separation of partic les is shortened in the case that particles coalesce.