Prater’s Air Classifying Mills operate by using the combination of two-stage closed circuit grinding/milling with an interstage air classifier all in one convenient unit. The internal air classifier continuously recirculates particles that are larger than desired back into the grinding zone ensuring an optimal final product particle size. When faced with materials that can be difficult to grind or that require a narrower particle distribution curve, the unique capabilities of the air classifying mill are often necessary. Large access doors on the air classifying mills allow for quick inspection or cleaning of the main rotor and classifier rotor.
Our air classifying mills are ideal for difficult to grind applications or narrow particle distribution curve requirements, and offers simple maintenance, uniform particle distribution, screen-less screen frame that prevents screen damage and wear and, lastly, a secondary inlet to provide additional air for an element of cooling. At Prater, safety is always first and all air classifying mills and fine grinders are equipped with an automatic door locking device to prevent accidental access to the inside while the rotor is operating. When using our Prater air classifying mills, three distinct steps are taken to process the material:
- Initial Grinding Stage: Using the secondary inlet, additional air adds a cooling element to the material being processed.
- Particle Rejection Stage: Particles that are larger than specified are rejected by the classifier and directed into the third stage.
- Final Stage: These particles go into a separate part of the grinding rotor designed specifically for difficult-to-grind pieces. This material is then directed to the classifier, which allows only properly-sized product to exit the machine.
Air Classifying Mill Case Studies
In addition to its two-stage closed circuit grinding and large access door, other great features include a final product size of 50 mesh to sub-micron size, interstage air classification and standard door interlock.