Fractionation and Segregation of Suspended Particles Using Acoustic and Flow Fields

Abstract

The exploratory research of applying an acoustic standing wave to a sediment flow stream to fractionate and segregate particles was investigated. Using fundamental physics of particles in an acoustic field, a mathematical model was developed to calculate trajectories of deflected particles due to the application of acoustic standing waves. Then at the bench scale, the above technology was implemented by building a flow chamber with two transducers at opposite ends to generate an acoustic standing wave. The technology was evaluated using uniform size silicon dioxide and silicon carbide particle suspensions in de-ionized water. Due to the acoustic force field, SiO 2 particles migrated toward the pressure nodes at half wavelength intervals at an optimum frequency of 333 kHz and 40 W power. Dark lines representing particle columns were formed after the application of the acoustic field, which was recorded in videotape. However, due to the small particle size of SiO2 , particle trajectories could not be recorded, hence the slightly larger sized SiC was used to track particle trajectories. The displacements of SiC particles due to an acoustic force were compared with the mathematical model predictions. For input power level between 3.0 and 5.0 W, the experimental data were comparable to mathematical model predictions. Also, from the experimental data it was possible to develop a relationship between input power and acoustic energy in the resonance chamber. Hence based on preliminary results it can be concluded that the acoustic field can be used either to segregate or fractionate fine particles.