Traveling wave transport of particles and particle size classification

Experimental research was carried out on transport of particles and particle size classification in a traveling electrostatic field. Particle conveyors which consisted of parallel electrodes were constructed and a four phase traveling electrostatic wave was applied to the electrodes to transport particles on the conveyor. The following points were clarified by the experiment: (1) Particles were transported almost linearly with time. Transport rate was also linear with applied voltage but a threshold existed due to adhesion force. (2) The direction of particle transport did not always coincide with that of the traveling wave but it was in part changed depending on the frequency of the traveling wave, the particle diameter, and the electric field. Motion of particles at low frequency was nearly synchronized with the traveling wave but at medium frequency it was opposite to and slower than the wave. Particles were vibrated but not transported at high field frequency. (3) Particles were efficiently transported under conditions of high electrostatic field with a rectangular waveform. (4) Particles essentially moved along the electric flux line, but electrostatic interaction and particle-particle and particle-conveyor collisions made trajectories complex. (5) Particles were classified according to size under application of voltages of appropriate frequency.