Patent GB-1177911-A (GB)
Title: Material-Suspending Air Current Differential Density Segregating Apparatus
Inventor: CRAVENS SAMUEL VINCENT
IPC: B03B4/00
Filed: 1968-01-23
Abstract: 1,177,911. Pneumatic separation. S. V. CRAVENS. 23 Jan., 1968, No. 3599/68. Heading B2H. [Also in Division G3] A material-segregating apparatus, e.g. for separating minerals from gangue or different types of minerals from one another, comprises a casing consisting of lower and upper sections 1, 2, Fig. 1, defining respectively an air chamber and a material-holding chamber, a floor 3 of air-permeable material in the lower portion of the casing section 2 for supporting material being segregated, a lower discharge port located in the casing upper section 2 immediately above the floor 3 for discharge of the heavy components, an opening in the upper portion of the upper section 2 for the discharge of light components, means supporting the upper section 2 including an upright shaft 6 the upper end of which is displaced orbitally with respect to its axis so as to effect vibration of the upper section, and air supply means to blow air from the air chamber through the floor 3 into the material-holding chamber for fluidising the material therein, whereby the latter is segregated due to the combined effect of vibration and fluidisation. The floor 3 may be made of woven glass fibre filter cloth laid over a bronze screen. The upward air current in the air chamber is produced by a fan 4 driven through V-belt 8 by a variable-speed motor 7. Louvres may be provided in the air chamber to straighten the air flow before it reaches the floor 3. The upper section 2 is resiliently supported on the lower section 1 by an assembly which comprises springs 13, 16, tube 14 and bolt 15 acting between flanges 9 and 10, 12 and which allows the upper section to move both upwardly and laterally relative to the lower section. The sections 1, 2 are interconnected by a resiliently stretchable web 17. In another embodiment, Fig. 8 (not shown) the sections 1, 2 are rigidly secured together and the entire casing is yieldably supported on to the base of the apparatus by means of springs and a cushioning ring. The shaft 6 is supported in bearings 18, 20 mounted in spiders 19, 21 and is rotated by belt and pulley 22, 23. The upper end of the shaft is connected through an eccentric drive (25, 26), Fig. 7 (not shown), to a spider 28 mounted in the bottom of the casing upper section 2 so as to effect orbital movement of the section relative to the axis of the shaft and to the casing lower section 2. During vibration of the upper section 2, its upper portion 2a may be steadied by springs 30 connected to posts 29. In a modification, Fig. 8 (not shown), vibration is effected by an unbalanced flywheel carried by shaft 6. In operation, material to be segregated is supplied by a screw-conveyor to a preferably telescopic tube 32 whose lower end is adjustably positioned relative to a filler block at the centre of floor 3 to provide an annular feed slot 34, jamming of the slot being prevented by the block being resiliently supported by a spring 35. After being segregated in the upper chamber 2 the light components overflow over the rim of the casing upper section 1 into an annular trough 37, forming part of a top closure structure 38 having an inspection and sampling opening closed by a hinged door 40, and are removed through tubes 42. The heavy components work their way down the incline of the floor 3 into an inwardly opening groove 43, Figs. 4 and 5, from which they are periodically discharged through circumferentially spaced ports the openings of which are controlled by rotatable valves 44 which are opened and closed simultaneously by an endless chain 48 engaging sprockets 47 on the individual valve stems, one of the valves being rotated, for example, by swinging an arm mounted on its stem by a fluid-operated actuator, Fig. 2 (not shown), which may be controlled manually or time-operated automatically. Discharge of the heavy components is assisted by sweeping the components with a current of air produced by part of the upward flowing air curling around an annular projecting flange 43' located below the floor 3. The heavy components enter into ante-chambers 51 and are removed through hoses 52. In another embodiment, Figs. 9, 13, the material to be segregated is supplied through a rotary feeder 68 and pipe 70 to a feed pipe 32' rotatably driven by sprocket and chain 73, 74 and centred at its lower end in a cavity 78, in a boss 77 carried by the floor 3. The feed pipe carries a lower rotor 80 which is slit to form tabs 81 which are twisted for propelling the heavy components radially outwards. The outer ends 82 of the rotor are received in the annular groove 43 for scraping the heavy components toward discharge openings controlled by valves 44' which are periodically reciprocated by fluid-operated actuators or by solenoids. Blades 82' at the end of upper rotor arms 80' carried by the pipe 32' scrape the light components from the trough 37. A number of segregator units may be connected in series, Figs. 10 and 11 (not shown), so that the lighter material discharged from each unit passes to the next unit and the heavier material discharged from each unit is collected as concentrate. Pumps of the compressible tube and roller type, Fig. 12 (not shown), are used to move the lighter and heavier materials. The amount of concentrate material removed from each unit may be regulated by a rotary timer mechanism (see Division G3) adjustable in accordance with the material being processed.