| 摘要 |
1,271,964. Coating apparatus. SINCAT SOC INDUSTRIATE CATANESE S.p.A. 30 July, 1969 [1 Aug., 1968], No. 38290/69. Heading B2L. [Also in Division C1] A method of coating fertilizer granules with a resin comprises the steps of supporting the granules in a frusto-conical fluidised bed 4 supported by a gaseous current having a temperature of at least 20‹C and injecting a foam formed by mixing an aqueous or organic dispersion or solution of one or more resins into the bed, the shape of the bed causing the granules to rise in the axis of the bed and fall near the periphery of the bed the granules receiving coating as they rise and that coating being dried by the supporting air as they fall. The supporting air is blown by a fan 1 through a heater 2 into the bed. Coating medium 5 is introduced by a nozzle 6 and compressed air, to aid dispersion, through a concentric nozzle 8. A cyclone 11 separates accidentally removed granules from the outgoing air stream. Granules are fed in through a pipe 9 and out through an overflow 14 and the process may be continuous or discontinuous. Several examples of coating are described. In one example a ternary fertilizer was coated with a medium of a 50% by weight dispersion of polyvinyl' acetate. The dispersion was foamed in a mixer and fed in to the coating apparatus with an air stream at 70‹C. In a second example fertilizer granules were coated with 10% by weight of polyvinyl acetate from a 20% dispersion of the resin.
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