Abstract: This invention relates to an apparatus and method for electrostatically separating particles having different electrostatic properties. The apparatus involves two thin box-shaped electrodes facing each other as mirror-images and charged with a voltage field causing the opposing electrodes to assume opposite charges, and then passing a mixture of particles through the field so as to make the particles travel toward the respective electrodes through a perforated plate or screen and to a solid back plate and then to fall by gravity through a splitter adjusted to separate particles attracted by one charge from particles attracted by another charge. A vibrator is attached to each electrode, which is isolated for movement by spaced vibration isolators to shake off any particles stuck to the electrodes.

Abstract: A method of separating particulate materials of different properties has been developed. It consists of feeding a mixture of dry, powdered materials to one end of the surface of a planar electrode, which is vibrating to move the particles forward. At least one type of the particulate materials acquires a charge via conduction or triboelectrification. Those particles that acquire charges of the same sign as that of the planar electrode are lifted and collected at the V-shaped counter electrodes installed above. The new separation method is particularly useful for removing unburned carbons from fly ash and any other conducting materials from nonconducting ones.