325 mesh corresponds to D97 ≈44 μm (US standard sieve). ACM mill is fully capable of stable continuous production of 325 mesh powder, and this is one of the most common operating setpoints across mineral fillers, diatomaceous earth, calcium carbonate, talc, powder coating and pigment industries. 325 mesh sits in the middle of ACM’s 120–800 mesh adjustable operating window.
Core PSD specification for ACM 325 mesh output
- D97 ≤44 μm (top cut, 325 mesh)
- Typical D50: 18–28 μm
- PSD characteristic: unimodal curve with sharp coarse cutoff, and a controllable fine tail.
Important note: Mesh is a sieve-based commercial specification; laser diffraction PSD (D97) is the actual QC index for ACM production.
Typical throughput (JACAN ACM reference, soft brittle minerals like diatomaceous earth)
- Small pilot ACM: 80–200 kg/h
- Medium industrial ACM: 600–1200 kg/h
- Large industrial ACM: 1200–2500 kg/h
Compared to 120 mesh coarse production, capacity at 325 mesh drops by roughly 30–40%. More internal particle recirculation inside the grinding chamber reduces net finished throughput and increases specific energy consumption.
Key ACM parameter tuning for 325 mesh
- Classifier wheel speed (primary control)
Set to medium-high VFD speed. Increase classifier speed to push D97 below 44 μm; reduce speed if excessive fines or over-grinding occurs. - Hammer count & rotor tip speed (directly links to your main article)
Moderate hammer count and medium rotor tip speed are recommended for 325 mesh.
- Too many hammers: generates excess submicron fine tail, broadens PSD, raises energy consumption, may cause filter blinding.
- Too few hammers: insufficient impact fracture, residual coarse particles, D97 fails to hit 325 mesh target.
- System airflow
Airflow is reduced from the maximum airflow used for 120 mesh. Lower airflow extends particle residence time to achieve enough fracture, but not so low that it creates excessive ultrafines. For high-density materials, maintain minimum duct velocity to prevent powder deposition. - Feed rate & feed condition
Stable loss-in-weight feeding, feed moisture controlled below 3–4%. Overfeeding leads to incomplete grinding and higher D97.
Material-dependent capability differences
- Soft porous minerals (diatomaceous earth, calcium carbonate): easiest to run stable 325 mesh with high throughput and low energy consumption (15–25 kWh/ton).
- Hard / abrasive minerals (crystalline silica): still achievable, but throughput falls, wear protection (ceramic/tungsten carbide liners) is mandatory, and energy consumption rises.
- Heat-sensitive materials (powder coating resin): can produce 325 mesh, but requires water-cooled grinding chamber to avoid resin melting, and hammer count must be limited to avoid excess ultrafines that ruin powder spray performance.
Auxiliary system requirements for 325 mesh production
- Dust collector: ePTFE membrane filter bags, higher pulse cleaning frequency than 120 mesh because more fine particles are generated. Compressed air demand increases slightly.
- Wear monitoring: regular inspection of hammers and classifier blades; component wear gradually shifts PSD coarser over runtime.
- Noise & power: higher classifier speed and moderate hammer count produce slightly higher noise and higher specific energy than coarse 120 mesh operation.
Limitations
- ACM can achieve stable 325 mesh, but PSD always contains a fine tail. If your product requires extremely narrow PSD with minimal submicron particles, additional post-classification may be needed.
- For very hard, tough non-brittle materials, 325 mesh production may become uneconomical due to high wear and low throughput.
ACM mill has reliable capability to produce 325 mesh powder with D97 ≤44 μm. It is a standard mid-fineness operating point. Operators tune classifier wheel speed as primary adjustment, and select moderate hammer count to balance fines generation, throughput and PSD span. At 325 mesh, throughput is lower than 120 mesh and specific energy consumption rises accordingly.
