GB533942A - Improvements relating to the separation and recovery of short fibrous asbestos from granular asbestos-bearing rock - Google Patents

Abstract

533,942. Systems for reducing asbestosbearing rocks. TURNER & NEWALL, Ltd.. and ELLISON, W. J. Nov. 14, 1939. No. 30064. [Class 59] Fibrous asbestos is recovered from its naturally occurring rocks by conveying the granular material in an air stream from a feeder casing 19 in which a high speed rotary beater operates through one or more similar units 20 ... 24, in all of which the material is treated solely by impact, the heavier rock particles being thereafter removed by collision with an adjustable baffle member 50 in a baffle box 33 and the complete separation of the asbestos being effected by subsequent known methods. The beaters are of similar construction and comprise a central shaft 25, Fig. 3, carrying rods 26 disposed angularly to each other and arranged spirally around the shaft; the angle may be 45 per cent. as shown. The rods may be arranged other than radially from the shaft and they may incline forwards or backwards to the direction of rotation. The beaters rotate at 750 to 2,500 revolutions per minute, 2000 being the normal speed. The profiles of the casings are similar to each other and are shaped so as to vary the clearance with the rod ends at various parts. The clearance in the zone 35 to 36 is about # inch; at the air-cutting point 37 about inch ; and from the point 38 to 40 the clearance gradually increases to about # inch. The casings may be arranged horizontally, vertically or angularly to each other. The feeder chamber 19 is attached to a supply chamber 16 over which air enters and is induced through the plant by a fan 28. The material is fed to the chamber 16 in a thin stream from a shaking table 12, the lower edge 15 of which is constituted by a wire screen of about “ inch aperture. In the plant shown, the fibre is separated from the smaller rock particles by a centrifugal separator 30, preferably of the cyclone type; a further separation may be effected by a rotary screen 54.