Abstract: An electrostatic sieve having a circular solid electrode, preferably with sawtooth contours arranged on its lower side concentrically around a center hole. The solid electrode is supported by insulating brackets around its perimeter. The brackets are attached to a conical outer structure, which also serves to collect the coarse particles. Underneath the solid electrode, with a gap between, is the sieve electrode, which is supported by a stretcher, preferably a circular ring of tubing with a square cross-section, itself supported on insulating brackets, which rest on an inner cone. The inner cone tapers toward the bottom to collect the fine powder passing through the sieve electrode, which passes through the hole in the bottom of the cone and falls into a collecting tray. The outer surface of the inner cone forms the inner surface of a conical passage, the outer surface of which is the outer conical support. Powder to be sieved is fed into the opening in the center of the solid electrode.

Abstract: This invention utilizes the oscillation which is produced in a powder which is acted upon by an electrostatic field. The disperser accomplishes its task by electrically charging the powder in a high voltage DC filed or by contact with a charging electrode, this causes the powder to become polarized and repel or disperse into discrete particles. The passing of particles from one electrode toward a second of opposite polarity will place a charge on the particle which causes oscillation, dispersion and movement toward the second electrode. Additional dispersion of the powder takes place as the particles oscillate and impact against the electrodes during the decent through the apparatus. Particle oscillation is related to particle polarity changes that occur as the particles traverse through the system.

Abstract: An apparatus for classifying particles by size comprising: a source of direct potential having first and second terminals, a sieve electrode connected to the first terminal, a solid electrode connected to the second terminal. Particles are fed to a transfer point located between the sieve electrode and the solid electrode such that the particles disperse and oscillate between the sieve electrode and the solid electrode whereby smaller particles pass through the sieve electrode. The new equipment has five adjustable operating parameters, screen angle, spacing between electrodes, field strength, powder input rate and electrode taper. The taper between electrodes is usually small, 0.3 to 0.4 of a degree with the larger opening at the top. The taper is used when the input powder is fine and the particle size differential is skewed either towards the high or low side. The purpose of the taper is to reduce the possibility of arcing at the input as well as to control dispersion of the particles.