GB734470A - Improvements in or relating to the cleaning and grading of asbestos fibre - Google Patents

Abstract

734,470. Sifting-apparatus. BOURNE, R. F., and CHEYNE, D. G. Oct. 21, 1953 [Oct. 21, 1952], No. 29076/53. Class 117. Asbestos fibres &c. are cleaned or graded by being passed horizontally through a closed space the bottom and upwardly divergent sides of which form a trough of screening mesh, in the lower part of which are rotary beaters of narrow elongated form arranged radially and moving closely to said lower part. In one embodiment, an exploded view of which is shown in Fig. 2, a casing 1 comprises removable top 5, sides 4 and hopper-shaped bottom 6. The U-shaped cradle 8 which supports the screening material is secured to beams 7 fastened to the casing, and comprises two halves with wide openings 9 separated by arcuate bands 10. The screening material 35, Fig. 3, is clamped to the cradle 8 by adjustable flexible straps 12, tightened by quick-straining buckles 15. The charge enters through opening 21 at one end of the top 5 of the casing and at the other end a tangential discharge duct 22 registers with an opening 23 in the cradle 8 through which the material, which has not passed through the screen, is guided by a deflector plate 24. For agitating the material in its passage through the screening region, a rotor 11, within the cradle 8, is driven by a motor 25. The rotor comprises a tubular member 26 carrying end flanges 27 between which are a plurality of radially-disposed bars 28 forming paddles. Short shafts, bolted to member 26, extend through elongated holes 32 in the ends of the cradle 8 and the ends 3 of the casing, into bearings, the height of which may be adjusted to regulate the separation of the rotor from the cradle. The opening 23 is provided with curved members 33, 34 facilitating the outward passage of the material and a pivotally mounted scoop may be provided capable of being tilted so as to close the opening. In a modification, a long length of screen material is mounted on rolls 36, 36a, Fig. 4, entering and leaving the casing through slots 37, so that a new area of material may be exposed to the cradle openings. In a further embodiment, sections of the screening material have a different mesh from inlet to outlet and a plurality of hoppers replace the single hopper of the first embodiment, Fig. 21 (not shown). Various arrangements of a number of the cleaner and/or grader units for performing a variety of separations are described, Figs. 9 to 20 (not shown).