GB639050A - Grinding and pulverizing method and apparatus - Google Patents

Abstract

639,050. Impact pulverizers. MACARTNEY PATENTS, Ltd. Jan. 17, 1947, No. 1620. Convention date, Jan. 18, 1946. [Class 59] In an impact pulverizer, portions of the material to be pulverized are rotated about a common vertical axis so that under the action of centrifugal force two streams of material are formed, one of which is caused to move in a substantially horizontal plane and the other upwardly in a path intersecting the first stream to bring about a collision of the two streams. In the apparatus shown, material is fed from a hopper 56 to the apex of a rotating inverted hollow cone 6 located within an inverted frusto-conical shell 18, open at its lower end, which is rotated at a lower speed in the opposite direction, the cone and shell defining a grinding chamber 17 which is closed at the top by a plate 23 secured to the shell and formed with apertures 61, 66 communicating with a collecting chamber 51 fitted with a delivery outlet 57 containing a suction fan 58. The cone 6 is formed with a lip 14 so that a lining of material is retained to minimize wear, and its edge 16 is so shaped that the material is flung outwardly and substantially horizontally against the wall of the portion 21 of the shell. The latter is formed with a flange 22 to retain a lining of material in the shell, and particles of material from this lining are urged upwardly by centrifugal force assisted by the draught created by the fan 58 and impeller vanes 59 formed on the cone so as to flow in a stream intersecting the horizontal stream of particles flung outwardly from the cone. Pulverization thus takes place partially by impact with the wall 21 and partially by collision between the streams of particles. Each aperture 61 is surrounded by flanges 63, having a higher leading edge than trailing edge so as to create a lift, and is covered by an inclined sieve 62. The apertures 66 may be opened or closed by a movable plate 67, and when these apertures are open the apertures 61 may be blanked off. The shell 18 is located and guided by rollers and is driven by a pinion 38 meshing with a ring gear 37. In a modification, Fig. 6 (not shown), suitable for grinding wet material, the top of the grinding chamber is completely closed, and delivery apertures fitted with sieves are formed in the wall of the shell below the level of the top of the cone. The impellers on the cone are omitted.