GB1161087A - Method and Apparatus for Processing Finely Dvided Particulate Material. - Google Patents

Abstract

1,161,087. Pneumatic separation. STURTEVANT MILL CO. 21 Nov., 1966, No. 52091/66. Heading B2H. [Also in Division A2] In classifying and cleaning finely divided particles, such as cereal grains and seeds, the particles are cascaded downwardly, and a suction-induced stream of air is passed upwardly to carry the lightest and heavier particles to an annular aspirating orifice, where the direction of the stream of air is suddenly reversed, to a downward direction as it passes through the orifice, so that only the lightest particles are carried through the orifice to a point of discharge. The lightest particles, e.g. hulls and dust, are thus separated from the heavier particles, e.g. grains and seeds. Apparatus, Figure 1, for carrying the classification and cleaning into effect comprises an outer housing having a central, cylindrical portion 2, an upwardly tapering, frusto-conical upper portion provided with a top opening 20 for admitting particles, and a lower, downwardly converging, frusto-conical portion 2a provided with a bottom opening, through which the heaviest particles and finally the heavier particles are discharged. The apparatus also comprises an inner housing having an upper conical portion 16 and a cylindrical skirt 14. An annular passage 18 is left between the outer and inner housings. Frustoconicallyshaped sides 24 project inwardly and downwardly from the lower part of housing portion 2. A vertically adjustable pipe 36 passes through slots 44 and 45 in the housing portions 2 and 14. These slots are sealed as by flange portions 50 and 58 adjustably secured to their respective housing portions by wing- nut fastenings. The inner end of the pipe 36 is turned vertically upwards, to form an elbow 40 and leave an annular aspirating orifice between the open, upper end of the elbow and the inner surface of the apex of the conical portion 16. The annular width of this orifice can be varied by vertical adjustment of the pipe 36. An adjustable damper D may be provided in the pipe 36 near its open, outer end, which is connected to a suction pump (not shown). A collector 21 with holes 22 around the periphery of its base is located at the apex of the inner housing portion 16. The threaded upper end of a rod 28 passes through a hole in said apex and a central hole in the base of the collector 21 and receives a wingnut 30. A compressed spring 32 is located between said base and a collar on the rod 28. The rod passes through the elbow 40 and leaves it through a bearing 42. The lower end of the rod 28 is secured to the apex of a hollow, upwardly tapering, conical deflector 26 to leave an annular gap 25 between it and the sides 24. The width of the gap 25 can be varied by turning the wingnut 30. Air inlet ducts 4 and 6 are directed, through the outer housing, towards the annular gap 25. Suction is applied to the pipe 36 to draw a stream of air through the ducts 4 and 6, the gap 25 and the annular aspirating orifice. Particles are fed, through the opening 20, into the collector 21 and spill over its lip and through the holes 22, and cascade down the passage 18, to the gap 25. The upward stream of air passing through this gap carries the lightest and heavier particles to the annular aspirating orifice.