Apparatus for granulating sodium percarbonate

摘要

Provided is a new granulator for preparing granules from a powdery material by agglomerating it through a kneading action, comprising a receptacle and two screws having screw blades disposed within the receptacle in parallel alignment to ensure intermeshing of the screw blades. The novel granulator consists of a feeding zone, a kneading zone divided into an upstream section and a downstream section, and a breaking zone. In the feeding zone, the blades on the two screws are forwardly conveying blades. In the upstream section of the kneading zone, on one screw a backwardly conveying blade is first provided and a forwardly conveying blade follows, and on the other screw, a forwardly conveying blade comes first and a backwardly conveying blade follows, said alternate arrangement occurring at least once in each screw. In the downstream section of the kneading zone, the blades on both of the screws are backwardly conveying screws. In the breaking zone, a plurality of small projections are provided on the peripheral surfaces of the screw shafts. The material transferred to the kneading zone from the feeding zone gradually advances while repeating a forward movement and a backward movement in an 8-figured pattern whereby it is agglomerated. The agglomerates are then broken by the projection in the breaking zone into granules of a suitable size.