How does an air classifying mill work?

The Air Classifying Mill combines a mechanical impact mill with a dynamic air classifying. Ideal for continuous processing of large batches, this mill is one of the most widely used mills today for pulverizing dry fine chemicals, food and other materials.

l Air Classifying Mill - Principle of Operation

l Applications.

l Conclusion

Air Classifying Mill - Principle of Operation

• The Air Classifying Mill is a vertical grinding machine incorporating an internal air classifying wheel with an independent drive.

• The product is fed into the grinding chamber via a feed screw or pneumatic conveying system through a rotary feed valve.

• The product is impacted by the high-speed grinding media, which breaks up the feed product and is thrown by centrifugal force against the grinding chamber wall, which in turn breaks up the product further. The broken particles are entrained in the induced airflow and released to the outer wall of the internal baffle assembly, which is equipped with an air baffle to laminarize the airflow. The laminar airflow and particles enter the internal classifying, which rotates in the same direction as the rotor disc. Oversized particles that are repelled by the centrifugal force exerted by the classifying wheel are thrown against the inner wall of the baffle and move downward by gravity and the pressure generated by the classifying. These oversized particles are then re-entrained into the grinding zone where further impact occurs.

• This cyclic action continues until all particles have passed through the classifying wheel. The product discharged from the classifying is transported in the process air stream where it is either collected in the cyclone or further classified in the cyclone classifying.

Applications.

• PPS air classification mills can be used in batch or continuous operation. They are used in industries that produce fine powders where controlled particle size distribution is required. Typical applications are; chemical, mineral, pharmaceutical, food, powder coating, etc. All systems are designed to handle inert and explosive applications where ventilation or containment is required.

• Typical applications for air classifying include

• Food Industry

• 12X and 14X grades of powdered sugar

• Gluten

• Ultra-fine flours

• Chemical industry

• Dye powder

• Carbon powder

• Dry adsorption powder

• Talc

• clay powder

• Pharmaceuticals

• Ultra-fine grinding of active pharmaceutical ingredients

Conclusion

• Air classification mills operate in the medium to fine particle size range, providing guaranteed accurate particle size and achieving steep particle size distribution with a minimum of ultrafine particles thanks to highly efficient, variable speed dynamic integral air classifyings.

• Our continuous improvements have created a broad product range suitable for processing a wide variety of even difficult materials. With no potentially damaging product temperature rise, the ACM is even suitable for grinding viscous, fatty or oily materials and has achieved considerable success in chocolate grinding.

• This type of mill operates on the impact grinding principle with high rotor speeds and impact edge speeds of up to 120 m/s. Size reduction is achieved by the influence of material particles on the rotating grinding surface (hammer or pin) and the fixed liner or grinding track. With the integral classifying design, particle size, distribution and cutting point can be precisely controlled by variable classifying speed.

For more information about air classifying, please visit our official website.

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