METHOD OF COATING PARTICLES BY ROTATING A FLUIDIZED BED OF THE PARTICLES

摘要

1,237,144. Coating particulate material. PFIZER Ltd. 24 July, 1969 [26 July, 1968], No. 35733/68. Headings B2E and B2L. [Also in Divisions C2, C3 and C5] Particulate material, especially of BS mesh size 10 or smaller, is coated by spraying the particulate material while it is maintained in the form of a fluidised bed which is rotating about a vertical axis. The coating material may be molten but is preferably applied as a solution or dispersion. The fluidised bed may be rotated by mechanical means within the bed e.g. a paddle steamer, at speeds of 100 r.p.m. or more. Particulate materials such as citric acid, sodium dihydrogen citrate, sodium bicarbonate, sorbic acid, gluconodeltalactone and commercial enzyme preparations such as the protease compositions used in detergents may be coated with waxes, resins, glycerides long chain fatty acids, cellulose ethers and non ionic surface active agents. Suitable apparatus comprises a casing 1, an inlet duct 2 and an outlet duct 3 through which gas is drawn by a fan 5. An annular platform 7 supports a vessel 8 which has a garage floor 11 situated between two perforated plates 12, 12a. A paddle stirrer 15 is provided within the vessel 8. A detachable filter hood 21 is supported by a ring 19 which carries a spray head 23 through which the coating material may be applied to the rotating fluidised bed A.