Patent GB-636503-A (GB)
Title: Improvements in or relating to the grinding or pulverizing of minerals and similar materials
IPC: B02C19/06
Filed: 1947-11-21
Abstract: 636,503. Impact pulverizers. PROCTER, H. A. Nov. 21, 1947, No. 28077. [Class 59] A method of reducing solid material to an ultra-fine state of division in non-rotary apparatus consists in treating the material with pressure fluid in a pipe-like pulverizing chamber so that flow of the material with pressure fluid through said pulverizing chamber is spirally around the centre line thereof, permitting the so-treated material to pass to a classifying chamber separated from said pulverizing chamber, and re-admitting insufficiently reduced material separated from the sufficiently reduced material from the classifying chamber to the pulverizing chamber for further treatment. A helical or spiral pipe-like pulverizing chamber 1 formed from an inner component 3 with a spirally grooved outer surface bolted to an outer component 2 with a co-operating spirally grooved inner surface, has material to be pulverized injected at 15, Fig. 3, into its lowermost convolution and jets of elastic fluid, e.g., air or steam, at 14 through nozzles 13 so arranged as to cause a swirling progressive helical motion of the fluid and material particles through and around the centre line of the spiral chamber, the particles being broken up by contact with the sides of the chamber. Vertical channels 16 connecting the several convolutions of the chamber 1 and ribs and grooves formed adjacent the upper ends of said channels allow heavier particles to fall from an upper to a lower convolution. The treated material is finally carried out from the chamber 1 through ports 5 into a classifying chamber 6, formed by the interior of the component 3. and thence around an extension 9 to an outlet 7 for the fines, heavier particles falling down on to a conical member 12 at the bottom of the classification chamber 6 where they are blown by a jet(s) 11 back through a port(s) 10 into the lowermost convolution of the pulverizing chamber 1. An outlet oppositely directed to the outlet 7 may be substituted for the cone 12. The nozzles 13 may be connected by individual pipes to a compressor or may be surrounded by a plenum chamber to which compressed fluid is admitted. In a modification, Fig. 8, the pulverizing chamber 1 is in the form of an annulus, treated material passing through an annular port 5a into the classifying chamber 6. A jet unit 28 projecting into the classifying chamber 6 has tangential jet apertures 28a at its base which blow insufficiently reduced material back into the pulverizing chamber 1 and an annular slit 28b in its upper part which serves to provide a fluid screen across the outlet 7 to prevent the escape of large particles. Renewable liner sections 32, 32a, Fig. 11, may be provided, and a plenum chamber 20 may supply fluid to the jet nozzles 13. The nozzles 13 may be angularly adjustable and of the type shown in Fig. 14. Another modification, Figs. 12, 13, comprises two superposed annular pulverizing chambers 1, 1a, material being fed into the upper one, the heavier particles from which chamber falling through channels 16 into the lower chamber 1a. Pulverized material passes through ports 5. 5a past gear-adjustable vanes 35 into a secondary classifying chamber 6a spaced inside which is a collector chamber 37 in communication therewith through ports 37a, the insufficiently reduced material being deposited in the chamber 6a, while the fines pass into the chamber 37, the ultra fines being collected from -an upper exit 39 and the normal fines from a lower exit 38. Features of the various modifications may be interchanged.