Patent GB-1298764-A (GB)
Title: Process and apparatus for separating mixtures of bulk materials
IPC: B03B4/00
Filed: 1970-02-12
Abstract: 1298764 Separating material by pneumatic and vibrating means BUEHLER AG GEB 12 Feb 1970 [21 Feb 1969] 6852/70 Heading B2H In a process for separating bulk material into fractions differing in specific gravity by vibrating a support which carries the material in the form of a bed and conveys it in a direction away from a material inlet whilst under the influence of the fluidising action of an air stream flowing through said support and bed, the air stream being collected in a hood above the support and being discharged therefrom, of one or more fractions of the bulk material is subjected to the action of one or more separate air streams which are subsequently discharged together with the fluidising air stream. In Figs. 1 to 3, an apparatus comprises a permeable support 1, feed inlet 20 for material to be separated, outlets 11-14 4 for the discharge of separated fractions of the material, a hood 2 arranged above the support I and the outlets 11-14 and connected to an air-discharge pipe 7, and a fluidising-air supply device 3. The apparatus is swingably mounted at one side on an oscilalting support 58 and at an opposite side is secured by straps 50 to a shaft 51 which carries bearings 61, 62 mounted on springs 52 supported on pillars 55, 56 which are adjustable in height above a base 10 by a rocker unit 60. Vibrations are imparted to the apparatus by a motor 80 having two eccentric weights 81, 82 and connected by straps 83 to the shaft 51. The air supply device 3 consists of air supply chambers 31 each associated with an adjustable opening 35 controlled by a damper valve 36 having an opening 37. A disc 41 having openings 42 constitute a movable flow shut-off member which is driven as a turbine wheel relative to the openings 35 by means of the fluidising air acting on vanes 43 on the disc whereby a pulsating flow of the fluidising air is established through the support 1. Alternatively, the shut-off member may be driven through a freewheel clutch and belting by means of the motor 80, Fig. 5 (not shown). Spaced flaps 45, which may be individually or collectively adjustable, Fig. 6 (not shown), to define adjustable slots 46 serve to regulate the discharge of the heaviest fraction from the support 1 whereas adjustable flaps 48 regulate the discharge of the different lighter fractions. As shown, the light fraction discharging through the outlet 12 passes down a pipe 91 which opens into a conduit 92 which has a converging air inlet opening 94, an adjustable injector-like constriction 95, a bent portion 98 and an inclined channel portion 97. The latter has an outlet opening 104 for the returned light fraction on to the support 1 and an air slot 102 which opens under the hood 2. In Fig. 4, the lightest fraction discharging through the outlet 11 passes via a pipe 132 into a vertical duct 122 which is provided with an inlet opening 135 for sifting air and an adjustable plate 128 for altering its flow crosssectional area. The heavy particles of the fraction falls into a sealing lock chamber 138 whereas the light particles are carried upwardly by the sifting air into a separator 124 from which the particles are discharged into a lock chamber 126 and the air into a pipe 125 which is connected with the air discharge pipe 7. Additionally the bulk material could be subjected to air-sifting in the region of the feed inlet 20 by means of a further air stream, which is also later discharged through the pipe 7, to effect a first removal of the lightest fraction of the material.