Patent GB-1307290-A (GB)
Title: Sizing screens
IPC: B07B1/08
Filed: 1970-08-07
Abstract: 1307290 Screening apparatus COAL INDUSTRY (PATENTS) Ltd 13 July 1971 [17 Aug 1970] 38130/70 Heading B2H  An apparatus for screening moist, small size particles of material, e.g. moist coal or claycontaining fine coal, comprises a circular screen 30 (32, 34), Figs. 1-3, consisting only of a plurality of elongated members 38 projecting from a hub 36 and rotatable about a generally vertical axis, drive means 16, 20, 18 for rotating the screen, means 21, 26 for feeding material on to the screen, first collection means 52, 54 56 positioned adjacent to the outer periphery of the screen for collecting oversize material, and second collection means 58 positioned below the screen for collecting undersize material. The hub 36 is secured to a shaft 2 belt-driven as at 14, 18 by a motor 16 through a constant or variable speed gearbox 20. The screen 34 is horizontal and the screens 30, 32 are upwardly, outwardly inclined at different angles to the shaft 2. Each screen comprises wires or thin bars 38, each attached at its inner end to the hub 36 by an L-shaped ring 40 and at its outer end to an L-shaped rim 42 after passing around a groove in a tensioning member 44 where it is held by a clamping device 46 or by a nut. The rim 42 is supported by radial spokes 48. The members 38 are decreasingly spaced from one another from the screen 30 to the screen 34. The shaft 2 is mounted in bearings 4 supported on a frame 6 carried on coil springs 8 or rubber mountings which are mounted on beams 10 and which permit the frame 6 to be vertically vibrated by a number of pairs of contrarotating motors 12 having out-of-balance weights. Material is fed to the screens via a hopper 21 in which it is agitated by radial arms 26 secured to the shaft 2. The screens are located within a casing 52 around the inside of which is hung a flexible rubber curtain 54 against which the oversize material is centrifugally flung from the rotating screens to drop down outlet chutes 56. Undersize material passing through the screens is discharged via a chute 58. A material distributing cone is shown at 60. In a modified form of screen, Fig. 6 (not shown), the elongated members 38 consist of spring steel rods of equal length. In a further modification, Figs. 7 and 8 (not shown), the rods are pivotably attached to the hub 36 so that they hang vertically when the screens are stationary and horizontally when the screens are rotated. In a second embodiment, Fig. 9, the frame is not vibrated. A horizontal distributing plate is shown at 73. Circular screens 80, 82, 84 secured to the drive shaft 2 consist of radial members 88 of unequal lengths. Spokes 90 provided beneath screens 80, 82 carry cylindrical curtains 91. Flexible rubber curtains 93 are provided adjacent the outer periphery of the screens. In a modification on the second embodiment, Fig. 10 (not shown), the middle and bottom screens (102, 104) are carried on curtains (108) carried at the outer ends of radial spokes (106) secured to the drive shaft (2) such that the inner diameter of the screen (102 or 104) is substantially equal to the outer diameter of the next higher screen (100 or 102). In further modifications: (a) the elongaged members constituting the screens form spiral patterns extending in or against the direction of rotation of the screen; (b) the elongaged members are arranged at an angle to the radius and may be directed towards or against the direction of rotation of the screen.