1. Background
A global materials manufacturer in Dresden needed ultrafine grinding of monocrystalline silicon powder to micron-level precision with a narrow particle size distribution (PSD). The customer supplies the semiconductor and photovoltaic industries, where tight control over both fine and coarse particle fractions is a hard requirement. Conventional milling equipment often struggles to deliver this level of PSD control.
The feed material was silicon powder, with about 15 kg provided for trial testing. The customer’s main concern was eliminating fine particles. Earlier grinding trials with other technologies had left too many residual fines in the product.
2. Grinding Targets
Two product specifications were defined, each demanding a tight PSD window and an 80% minimum yield:
| Paramètre | Target 1 (Coarser) | Target 2 (Finer) |
| D1 | 3 μm | 3 μm |
| J10 | 6 μm | 5 μm |
| D50 | 10–14 μm | 6–10 μm |
| D90 | 18–23 μm | 10–15 μm |
| D100 | < 40 μm | < 30 μm |
| Target Yield | 80% | 80% |
The critical constraint was the fine-end cutoff: D1 above 3 μm and D10 above 5–6 μm, meaning virtually no sub-3-micron particles could be present. This ruled out simple single-pass grinding and required integrated classification.
3. Solution: MQW03 Laboratory Jet Mill
Epic Powder ran the trial on the MQW Broyeur à jet à lit fluidisé. The fluidized bed design was chosen because of its built-in turbo classifier, which adjusts particle size in real time during grinding. Oversized particles are continuously sent back to the grinding zone, while on-spec particles exit the chamber. This is what makes the narrow D1-to-D100 span achievable.
Key process features included:
- High-speed classification wheel to sharply cut off oversize particles above D100 limits
- Optimized airflow parameters to minimize over-grinding and fine particle generation
- Multi-pass classification to ensure fines were thoroughly separated from the product stream
4. Results
After tuning the process parameters, the MQW jet mill produced powder meeting both target specifications. The PSD curve below shows the narrow distribution achieved for Target 2:
The measured span came in under 1.0, which is a very tight distribution for jet-milled silicon powder. The bimodal peak that often shows up with impact-milled materials was completely gone, confirming that fine particles were effectively separated out.
5. Conclusion
The case showed that the Epic Powder MQW fluidized bed jet mill can deliver narrow-PSD ultrafine grinding of monocrystalline silicon for the semiconductor supply chain. The built-in classifier was key to hitting the D1 and D10 targets while keeping yield at 80%.
For questions about jet mill solutions for silicon, battery materials, or other powder applications, contact our technical team.
Paramètres techniques :
Matériel: Monocrystalline Silicon
Équipement: MQW03 Laboratory Fluidized Bed Jet Mill |
Industrie: Semiconductor / Advanced Materials
Sortir: 59kg/h