The ACM fine impact mill, also known as Air Classifier Mill, is an integrated grinding and air classification system. It combines high-speed impact comminution with dynamic centrifugal classification inside one compact machine, enabling continuous production of fine powder with controlled particle size distribution.
1. Feeding stage
Raw material is fed into the grinding chamber by a quantitative feeding device. Controlled feed rate ensures uniform material loading, preventing overloading that weakens grinding efficiency or causes unstable particle size. Material enters the grinding zone and immediately meets the high-speed rotating grinding rotor.
2. Impact & shear grinding
The rotor is fitted with grinding blades. As it spins at high peripheral speed, particles receive strong impact, shear and particle-on-particle collision forces. Bulk materials are shattered into fine fragments instantly.
This is a screenless grinding design. There is no mesh screen to limit particle size. Instead, particle size is controlled by the built-in air classifier. Coarse particles stay in the grinding zone and keep being struck repeatedly until they are fine enough to enter the classification area.
3. Dynamic air classification (core working principle)
An independently driven classifier wheel sits at the outlet of the grinding chamber. The rotating classifier wheel creates centrifugal force, while the system airflow produces drag force on particles.
- Coarse particles: Centrifugal force is larger than air drag. They are thrown back to the grinding chamber for re-grinding.
- Fine particles: Air drag overcomes centrifugal force. They pass through the classifier wheel along with airflow and move toward the product collector.
By adjusting the classifier rotation speed via frequency converter, operators change the cut point of particle size. Higher classifier speed gives finer finished powder; lower speed allows larger particles to pass through.
4. Powder collection
Qualified fine powder is carried by airflow into the pulse jet dust collector. Fine particles are separated from air and collected as final product. Clean air is discharged after filtration.
5. Closed-loop recirculation
The whole process forms a closed internal loop. Oversized particles are continuously returned to the grinding zone for repeated comminution. This recirculation maintains stable PSD and avoids coarse powder leaking into finished goods.
Key advantages of ACM fine impact mill working mechanism
- Integrated grinding + classification in one unit, compact layout.
- Screenless structure, no screen clogging issue.
- Particle size adjustable online without stopping production.
- Suitable for a wide particle range, typically from several microns up to 100 μm.
- Optional ceramic lining available for high-purity powder processing to eliminate iron contamination.
The ACM fine impact mill relies on high-speed impact and shear to break materials, then uses the dynamic classifier wheel to separate fine particles from coarse fractions. Coarse material recirculates for re-grinding, while qualified fines are collected by the dust collector. Tuning classifier speed and airflow is the main method to control final particle size.
