Patent GB-623820-A (GB)
Title: Improvements in or relating to a method of and apparatus for crushing or grinding material
IPC: B02C17/18
Filed: 1946-11-04
Abstract: 623,820. Grinding and crushing mills. CROSS, E. J. (Nordberg Manufacturing Co.). Nov. 4, 1946, No. 32687. [Class 59] A grinding or crushing mill comprises a rotor having a flexible circumferential wall defining a grinding or crushing zone within the rotor, a feeding device for delivering the material to be treated, with or without a charge of balls, to the zone, a stationary impact member in the zone, and means for flexing the wall inwardly whereby material moved outwardly against the wall under the action of centrifugal force is directed against the impact member. The mill shown comprises a rotary structure consisting of a cylindrical member 81 supported from a sleeve mounted on bearings 30, 31, a concave flexible wall 86, inner and outer rings 52, 53 secured to plates 49, 51 separated by radial curved fan blades 50, a plate 57 supported from the plate 49 and having an upwardly inclined edge 60 furnished with radial vanes 62, and a perforated screen 63 secured to a ring 65 which is furnished with radial vanes 66 and terminates in a horizontal position 67. A ring 55 having a sharp edge is mounted above the ring 53, and the gap between the rings may be covered by a perforated screen 54. The plate 49 is supported from a sleeve mounted on bearings 33, 34 and is driven by gearing 36, 37. Sealing rings 17, 18 are provided between the plate 49, 51 and a casing A which receives the ground material, and a seal 82 between the member 81 and a fixed member 83. Within the grinding chamber is a fixed impact member 123 pivoted at 121 to a supporting plate 120 and angularly adjustable by means of a hydraulic cylinder 135. A second impact member 129 is fixed to the plate 120. The wall 86 is flexed inwardly by a roller 95 mounted on a pivoted support and adjustable by screw and nut mechanism 110. Figs. 10 and 11 (not shown) illustrate modified arrangements employing two or four rollers. The material to be ground together with a charge of balls is fed from a hopper by a reciprocating plunger to a funnel 28 and passes down a fixed sleeve 26 to inclined discharge outlets 24. The material and balls are held against the wall 86 by centrifugal force until they are deflected inwardly against the impact members by the roller 95, the path of the material and balls being as shown by the arrows in Fig. 3. The fines are withdrawn through the screen 63 by the air current created by the fans and are flung across the gap between the rings 52, 53 by the vanes 62. The downward air current through the gap carries away the finer particles, and the coarser particles pass over the edge of the ring 55 for regrinding. The size of the particles may be determined by adjusting the height of the rings 55 and/ or ring 60 and the width of the gap. The air passes in a closed circuit through the mill, and the air and ground material passes from the casing A into a settling chamber B, Fig. 1 (not shown), fitted with arcuate baffles. A cyclone separator may be used. In a modification, Figs. 8 and 9 (not shown) the ground material is removed from the casing A by a rotary scraper and an additional fan is employed to boost the air circulation.