GB1011207A - Improvements in or relating to apparatus for separating solid particles of differentsizes - Google Patents

Abstract

1,011,207. Pneumatic separators. COLLECTION Ltd., and D. SUMMERS. Sept. 25, 1964 [Sept. 27, 1963], No. 38257/63. Heading B2H. An apparatus for separating particulate solid material according to size or density comprises a substantially vertical duct 10, Fig. 1, or 45, Fig. 2, opening at its top end into a transverse duct 11 or 46, a feed tube 24 or 61 through which the material is fed downwardly into the duct 10 or 45 and extending downwardly through the duct 11 or 46 to a position below the top of the duct 10 or 45, means for producing an upwardly flowing current of air at a predetermined velocity in the duct 10 or 45 so as to carry upwardly the smaller or lighter particles, means for producing another current of air in the duct 11 or 46 in order to convey the smaller and lighter particles along that duct, and means at the bottom of the duct 10 or 45 for collecting the larger or heavier particles. In Fig. 1, the material to be separated is fed from a hopper 26 via a screw conveyer 27 into the feed tube 24, agglomerations in the material being broken by apertured discs 28, 29 which rotate in opposite direction to each other in the tube 24. Air is fed to the ducts 10, 11 by means of a blower &c. 18. A flap 23 regulates the air flow in the duct 11 and in a transverse duct 13 leading to the duct 10. The air passing from the duct 13 is distributed evenly in the duct 10 by means of vertically overlapping rings 15. The heavier or larger particles are collected in a bag 17 while the lighter or smaller particles are conveyed to a cyclone 19 where the air is exhausted at 22 and the particles are collected in a bag 21 or are discharged through a valve. In Fig. 2, the feed tube 61 is rotatably mounted in the duct 45 and terminates in a fish-tail spreader portion 62 opening above a guiding grid 68. A sleeve 67 serves to adjust the air gap between the tube 61 and the hopper 66 so as to adjust the rate of flow of air drawn into the tube and hence to vary the speed of fall of the feed material. The two air currents are produced by air sucked through the apparatus by a fan 58 via ducts 46 and 48 provided with butterfly valves 53, 54 which are coupled by a link 55 for simultaneous operation. The heavier or larger particles are discharged through a valve 52. The feed arrangement of Fig. 1 can be used in the apparatus of Fig. 2 and vice versa. The apparatus may be used for treating tea so as to separate dust and very small leaf particles from the leaf fragments of more normal size.