corn straw

Within the first minute of dry grinding, a fineness of < 300µm as desired has been reached. Because sample did not start sticking, even longer dry grinding times are plausible (see result 2).

Final fineness has been determined by optical microscopy.

Sample 2 has been dry ground until a sticking of sample has been observed.

This uses to happen after the majority of particles reached a fineness of < 20-30µm. Interacting forces between fine ground particles will become bigger as their own g-force. Therefore, particles will stick to each other and just become compressed by the used grinding balls. These clusters of particles also contain bigger particles which will not be ground any further too.

A longer dry grinding time is not recommended.

Final fineness has been determined by optical microscopy.