GB1036604A - High tension separation of materials - Google Patents

Abstract

1, 36, 604. Electrostatic precipitation. CARPCO RESEARCH & ENGINEERING Inc. Oct. 20, 1964 [July 10, 1964], No. 42713/64. Heading B2J. Particles of varying conductivity contained in a mixture of particulate materials are separated by subjecting the mixture while disposed on a grounded conductive surface to a spray of mobile ions produced by a corona discharge pulsed at a rate of about 150 to 800 pulses per second, removing the mixture from the spray of mobile ions, and separately collecting the particles pinned to the grounded conductive surface by the mobile ions and the particles not so pinned. The process is especially directed to the separation comminuted ores containing fine particles ranging in size from 200 mesh down to 5 microns. Mineral particles 38 are fed from a hopper 12 on to an earthed rotor 10 of electrically conductive material and revolving at high speed (e.g. 900- 1500 ft. per min. for a 14-16 inches dia. rotor). The particles are subjected to an ionizing field from an electrode 14 having a corona discharging wire portion 16 directed radially toward the rotor so that the particles become discharged. The conductive particles contact the rotor and have their charges reversed whereas the non-conductive particles do not suffer reversal of charge and become pinned to the surface of the rotor. The conductive particles are then subjected to an external electric field produced by an electrode 20 which may be powered by a different or, as shown, by the same source 18 of unindirectional pulsed voltage (10-100 KV) as the electrode 14. The relatively light conductive particles 40 under the influence of the electric field and also of centrifugal and gravitational forces are removed from the rotor surface and are displaced towards the electrode 20 which may also be provided with an corona discharge wire 22 directed away from the rotor and serving to displace the particles further away from the rotor so that they fall in a compartment 50. As the rotor continues to rotate, the heavier con - ductive particles 44 together with some of the gangue material fall by gravity via compartment 48 to form a middling fraction. The majority of the pinned non-conductive particles 42 are removed from the rotor, surface by a wire electrode 30 connected to a high-frequency A.C. source 32 and fall via compartment 46 as a tailing fraction. Any remaining non-conductive particles still remaining on the rotor are physically removed by a brush 34. The middling fraction may be recirculated to exhaustion to increase the recovery of valuable components of the ore. Dimensional features of the apparatus and experimental results are given.