GB1234031A - - Google Patents

Abstract

1,234,031. Granulating. CALMIC ENG. CO. Ltd. 26 July, 1968 [28 July, 1967; 7 June, 1968], Nos. 34763/67 and 27277/68. Heading B5A. [Also in Division B2] A method of granulating or coating material particles comprises passing a gas stream upwardly through the perforated bottom of a chamber, said bottom having an inverted frustoconical surface and an upright conical projection in the centre of said surface, whereby a fluidized bed of said particles is formed and an upwardly directed converging flow of particles in the centre of the chamber is provided, and passing one or more gas streams downwardly from above the fluidized bed, said stream or streams entraining finely dispersed granulating or coating material. A coating chamber 1 has a perforated bottom 3 of inverted frusto-conical form and having at its centre an upright conical projection 5. Chamber 1 is continued upwardly by a diverging expansion chamber 2 closed by the fine-meshed filter fabric 9. A nozzle 6 positioned above chamber 1 is supplied with compressed air and granulating or coating material by ducts 7 and 8 respectively. Fabric 9 is arranged to be mechanically shaken to dislodge fine particles entrapped thereon. Variation of pressures in chamber 2 is arranged to control the supply of fluidizing compressed air through bottom 3. As an example of granulation, a fluidized powder containing 80 lb. sucrose, 9 lb. ascorbic acid, and 6 lb. acacia is sprayed with a liquid prepared by dissolving 4 lb. gum acacia in 2 gallons of water. The apparatus may be used for coating, e.g., tables with either liquid or with powder.