Because the classifying wheel of the Powderplex mill sits on and co-rotates with the grinding disc, only one rotor, one bearing unit and one drive are necessary. Dependent on the required product fineness, the APP is equipped to order with a classifying wheel for coarse, medium or fine separations. A spacer is used to effect a rigid connection between the classifying wheel and the grinding disc.
Fed by an air-sealed feed metering unit, the feed product enters the machine via the feed socket onto the wear plate of the beater disc, where it is uniformly distributed, intercepted by the impact beaters and catapulted against the grinding track. Comminution is a result of the product impacting against the impact beaters and the grinding track.
The working air enters tangentially and flows between the beater disc and the grinding track into the grinding chamber. The comminuted product is conveyed out of the grinding zone by the air. It is transported upwards along the outside of the deflection cone and deflected to the classifying wheel. The working air extracts the fines portion from the product and conveys it through the vanes of the classifying wheel to the fines discharge. The coarse material is rejected by the classifying wheel and gravitates downwards for further comminution. The product is separated from the air in a downstream collection unit, usually a filter. A narrow gap between the labyrinth seal and the classifying wheel prevents unclassified product from migrating into the fines. To order, this gap can be automatically rinsed by air. Rinsing (compressed) air protects the bearings against product ingress.