GB1377579A - Centrifugal sifter - Google Patents

Abstract

1377579 Centrifugal classifiers J WESSEL 24 May 1972 24326/72 Headings B2H and B2P A centrifugal sifter, Figs. 1 and 2, comprises a rotor 2 which rotates in a housing 1 and is charged centrally with material to be sifted (arrow 24), and which contains material distributing passages 15 which lead the material outwardly to air-sifting zones 16 from which the fine material (arrow 24a), which is deflected inwardly again, passes to exhaust openings 18 arranged in the vicinity of the rotor periphery. The rotor 2 consists of circular discs 5, 6 with members 7 disposed therebetween and defining the distributing passages 15 and U-shaped exhaust passages 17 which lead sifting air and the fine material to the exhaust openings 18 which are provided in the lower disc 5 of the rotor and communicate with a collecting chamber 13 from which the air and the fine material are sucked by a fan (not shown) via a pipe 14 and a cyclone (not shown). The material to be sifted is introduced via a feed pipe 11 and a collar 10 through a central opening 9 in the upper disc 6 of the rotor. Rods 19 disposed upstream of the passages 15 serve to break up agglomerates of the material. The coarse material (arrow 24b) is thrown out of the sifting zones 16 by centrifugal force and led off through a hopper 1a against counter-flowing air (arrow 23) which effects further separation. In Fig. 3, the rotor 2 rotates about a horizontal axis 4'. The housing 1' is spiral shaped and is provided with an opening 26 which serves both as an inlet for sifting air and as an outlet for the coarse material. Further parttangential inlets for the sifting air are provided at 25. The air and fine material are discharged via the collecting chambers 13' and the pipe 14'. In a modification, Fig. 5 (not shown), a baffle plate (27) adjustable about an axis (28) parallel to the axis of rotation of the rotor is disposed in each of the sifting zones (16') to maintain a uniform flow profile. In a further modification, Fig. 6 (not shown), a number of baffle plates (29, 30) are so disposed with their outer edges staggered. In a still further modification, Fig. 7, the exhaust openings 18' are disposed between limbs 31 of hairpin-shaped ribs. Two or more systems of distributing passages, sifting zones and exhaust openings may be provided in series in the axial direction in mirror-image relationship to each other, each system comprising an associated collecting chamber, and a material charging means common to all systems being provided on one side of the rotor and its overhung mounting on the other.