Patent GB-1391256-A (GB)
Title: Apparatus for separating and classifying mixtures of particulate materials
IPC: B07B4/06
Filed: 1971-04-20
Abstract: 1391256 Pneumatic separators; centrifugal separators BIRTLEY ENG Ltd 18 April 1972 [20 April 1971] 10125/71 Headings B2H and B2P [Also in Division G3]  An apparatus for the separation of a mixture of particulate materials of different densities comprises means for causing said mixture to move in a circular path and means for generating an air flow radially inward through said path. The mixture may be caused to move in a circular path by rotating a cylindrical or frusto-conical surface or by entraining the mixture in a carrier fluid which is caused to flow around a stationary surface in the manner of a cyclone. In the embodiment shown in Fig. 3, a basket 42 having an air-permeable frusto-conical wall is rotated and also oscillated in an axial direction by a unit 50 driven by hydraulic motors 53 and 56 via belt drives 55 and 57. The unit 50, Fig. 6, comprises a reciprocable rod 95 located on an eccentric journal 96 of a shaft 58 by bearings 97. The basket 42 is secured to a rotor 99 by resilient means 83 and is also secured to a head 103 rotatably mounted on the rod head 104 by a bearing 105. An annular resilient member 110 is disposed between a cap 106 and the head 103, the cap 106 being secured to a cylindrical member 107 fast with the rotor 99 by rods 108 passing through bores in the member 110. The rotor is mounted on a housing 93 by bearings 100 and 101 and is secured to a pulley 54 which is driven by the belt drive 55. The particulate material is fed into the basket through a funnel 64 and directed by baffles 65 and 66 onto the wall. A pulsating flow of air is supplied through a pipe 51 and flows through a housing 49, and passages 48 and 47 to a chamber 44 from which it passes radially inward through the wall of the basket 42. This causes stratification of the particulate material with the lighter material disposed radially inward of the heavier material. The heavier fraction travels up the wall of the basket and is discharged over the upper rim thereof into a chamber 59 from which it is discharged through a chute 62. The lighter fraction travels in a downward direction and is discharged through apertures at the base of the frusto-conical wall. A gas-tight seal 126 is provided between the stationary pipe 51 and the rotating housing 49. In another embodiment, Fig. 1, (not shown), the air chamber (6) surrounding the air-permeable wall of the rotating basket 1 is stationary and the light fraction of the particulate material is withdrawn from the basket through a suction duct (15). In a further embodiment, Fig. 5, the rotating basket 42 is disposed with its axis horizontal and the operating conditions adjusted so that both the lighter and heavier fractions flow in the same direction. A stripper plate 88 separates the two fractions when they reach the wider end of the basket. In another embodiment, Fig. 7, the air-permeable frusto-conical surface 111 is stationary and surrounded by an air chamber 112. The particulate mixture is entrained in an air stream admitted through a tangential inlet in the lid 114 and which flows spirally around the surface 111. Both the heavier and lighter fractions flow downwardly, the latter being drawn up through a pipe 116 by a fan 115 to a settling chamber 117 from which it is discharged through a chute 118.