GB753139A - Improved method and apparatus for dispersing fine particles - Google Patents

Abstract

753,139. Conical mills. SHURTS, R. B. Jan. 1, 1954 [April 15, 1953], No. 69/54. Class 59. A method of dispersing fine particles e.g. pigment particles, in a liquid medium e.g. in paint manufacture comprises mixing the particles in a vehicle to form a suspension containing wetted particles and agglomerates thereof, supplying the vehicle and suspended particles under pressure between relatively movable grinding surfaces defining therebetween a clearance which decreases from the supply end to the discharge end over at least a portion of the extent of the grinding surfaces between the supply and discharge ends, subjecting the wetted particles and agglomerates while between the grinding surfaces to a centrifugal force opposed to the supply pressure whereby the agglomerates are thrown back towards the supply source and are separated from the wetted and dispersed particles, and thereafter collecting the wetted and dispersed particles so separated. A high-speed stone mill for carrying out the method comprises a stator 10 having a frusto-conical cavity in which a rotor 12 is supported, the rotor and stator defining between them a material dispersion passage A and the clearance between the rotor and stator decreasing from the upper diameter of a section 15 of the rotor to the upper diameter of a section 14 of the rotor, and then being uniform from the upper diameter of the section 14 to the lower diameter thereof. A like effect may be obtained by variant conical tapers on the stator and rotor or on the stator only. The material is supplied under pressure from a container 1 by a pump 2 to an inlet port 4 disposed in an air-tight chamber 9. The processed dispersion is discharged through a port 13 in the stator to a spout 30. The stator and the rotor section 14 are of fine grit and the rotor section 15 of coarse grit. The rotor is driven through a belt 29 and pulley 28 from a variable-speed power source and is vertically adjustable relative to the stator by having the lower end of its shaft 17 mounted on a thrust bearing 23 supported on an internally screwthreaded plate 24 co-operating with a fixed screwthreaded stud 25, the plate 24 being locked in adjusted position by means of a resilient pawl 27 engaging one of a plurality of notches in the periphery thereof.