Air classifying mills are widely used in the fine grinding process, especially for heat-sensitive and hard-to-grind materials. They offer precise particle size control and are efficient in producing fine powders.
Core Components and Function
Grinding Chamber
The heart of the air classifying mill is the grinding chamber. Here, materials are subjected to repeated impact and attrition by rotating hammers or blades. The rapid collision reduces the particles to a fine powder.
Classifier
Adjacent to the grinding chamber is the classifier. It controls the particle size by allowing only particles of a specific size to pass through. Larger particles are returned to the grinding chamber for further reduction.
Operational Process
Feeding Mechanism
Materials are fed into the air classifying mill through a feeding mechanism, which ensures a steady flow of material into the grinding chamber.
Impact and Reduction
Inside the grinding chamber, high-speed rotating hammers or blades impact the material, breaking it down into finer particles.
Air Classification
The classifier wheel, operated by an independent motor, allows fine particles to pass and directs larger particles back into the grinding chamber. The speed of the classifier wheel determines the particle size.
Collection of Fine Powders
Finally, the fine powders are collected through an outlet, while the air used in the process is filtered and released.
Key Parameters and Specifications
- Power: Air classifying mills come in various power ratings, typically ranging from 5 kW to 200 kW, depending on the model and intended use.
- Efficiency: These mills are known for high efficiency, often exceeding 90% in optimal conditions.
- Cost and Budget: The cost of an air classifying mill can vary widely, from a few thousand to over a hundred thousand dollars, depending on size, capacity, and features.
- Size and Dimensions: They are available in different sizes, from small laboratory-scale models to large industrial units.
- Material Quality: Constructed usually from high-grade steel or alloys for durability.
- Speed: The rotational speed of the blades and classifier wheel is a critical parameter, often adjustable to suit different materials and desired particle sizes.
- Lifespan and Maintenance: With proper maintenance, these mills can have a long operational life, often several years.
Advantages and Disadvantages
Advantages
- Precise control over particle size distribution.
- Suitable for a wide range of materials, including those sensitive to heat.
- High grinding efficiency and fine particle production.
Disadvantages
- Higher initial cost compared to some other milling technologies.
- Requires regular maintenance for optimal performance.
- Not suitable for materials with high oil or fat content, as this can lead to blockages.
For more information on advanced milling technology, explore the Fluidized Bed Jet Mill.