Patent EA-004354-B1 (EA)
Title: Apparatus for electrostatically separating a feed mixture of two types of particles and method therefor
Inventor: YAN ERIC
IPC: B03C7/12
Filed: 2001-06-20
Abstract: 1. An apparatus for electrostatically separating a feed mixture of two types of particles which comprises feeding the mixture into the upper end of a free-fall space separating two rectangular electrodes positioned on opposite sides of said free-fall space as mirror-images of each other, each said electrode including a frame, a faceplate, and a back plate parallel to each other and joined to each other by two vertical end panels to at least partially enclose a thin box-shaped space, said faceplate of each electrode being a perforated panel through which oppositely electrostatic feed particles may be attracted and pass, and said back plate being of electrical conductive sheets and means for applying a high voltage opposite charge to each of said electrodes. 2. The apparatus of claim 1, wherein said faceplate is a metallic screen. 3. The apparatus of claim 1, wherein said back plate and said end panels are metal sheets. 4. The apparatus of claim 1 further comprising an adjustable splitter adjacent a lower end of the said free-fall space, having a collection zone to receive particle middling with particle rejects being adjacent one of said electrodes and particle products being adjacent another said electrode. 5. The apparatus of claim 1 wherein each said electrode includes a vibrator attached to said frame, said vibrator providing vibrations to said electrode to cause any particles temporarily stuck to said electrode to be shaken therefrom. 6. The apparatus of claim 5 further comprising a housing, stationary support means for mounting said electrodes in said housing, vibration isolators positioned between said electrodes and said support means to isolate vibrations from each said vibrator from passing through said support means. 7. The apparatus of claim 6 wherein one said support means is located within and in a top portion of said electrode and another said support means is located below a bottom of said electrode. 8. The apparatus of claim 6 wherein said vibration isolators include a top pair of spaced isolators and a bottom pair of spaced isolators, all said isolators being adjacent respective corners of each said electrode. 9. The apparatus of claim 1 wherein said electrodes are angled from vertical and with respect to each other. 10. The apparatus of claim 1 further comprising a housing and stationary support means for said electrodes, high voltage insulators between said housing and said support means to permit connection of said means for applying a high voltage of opposite charge respectively to said electrodes. 11. An apparatus for electrostatically separating a feed mixture of two types of particles which comprises feeding the mixture into the upper end of a free-fall space separating two rectangular electrodes positioned on opposite sides of said free-fall space as mirror-images of each other; each said electrode including a frame, a faceplate, and a back plate parallel to each other and forming with said frame a thin box-shaped space, said faceplate of each electrode being a perforated panel through which oppositely electrostatic feed particles may be attracted and pass, said back plate and said perforated panel being electrically conductive, and means for applying an opposite charge of high voltage to respective said electrode and providing said faceplate and said back plate of respective said electrode at the same voltage to minimize the electric gradient between said faceplate and said back plate across said boxshaped space. 12. The apparatus of claim 11 wherein each said electrode comprises a pair of vertical end panels attached to said frame and at least partially enclosing said box-shaped space, said back plate and said end plates being metal sheets. 13. The apparatus of claim 11 wherein each said electrode includes a vibrator attached to said frame, said vibrator providing vibrations to said electrode to cause any particles temporarily stuck to said electrode to be shaken therefrom. 14. The apparatus of claim 13 further comprising a housing, stationary support means for mounting said electrodes in said housing, vibration isolators positioned between said electrodes and said support means to isolate vibrations from each said vibrator from passing through said support means. 15. The apparatus of claim 14 wherein one said support means is located within and in a top portion of said electrode and another said support means is located below a bottom of said electrode. 16. A method for electrostatically separating a feed mixture of two types of particles comprising the steps of: - feeding the mixture into the upper end of a free-fall space formed by a device of claims 1-15; - applying a high voltage opposite charge to the electrodes by which the faceplate and back plate are at the same voltage to minimize the electric gradient therebetween thereby enhancing particle separation; - passing oppositely charged electrostatic feed particles through the perforated plates to the back plates of the electrodes; and - recovering separated particles from the electrodes. 17. The method of claim 16 further including the steps of: - directing separated particles in the free-fall space into an adjustable splitter adjacent a lower end of the free-fall space; and - collecting the recovered particle middling generally centrally with particle rejects being adjacent one electrode and particle products being adjacent the other electrode. 18. The method of claim 16 further including the step of: - vibrating the frame to cause any particles temporarily stuck to an electrode to be shaken therefrom. 19. The method of claim 16 wherein vibrating is provided by vibration isolators mounted between the electrodes and the support to isolate vibrations from each vibrator from passing through the support.