Wool Fibers

For a grinding of organic compounds, rough surfaced sintered corundum will be recommended. With the sintered surface, also a higher abrasion of grinding material (Al2O3) is expected to be found, compared with other materials like zirconium oxide or steel.

After 30 minutes of dry grinding, sample starts sticking to bowl and balls.

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

To achieve a better fineness, only a grinding in suspension is plausible.

To determine particle size after 30 minutes of dry grinding, the Laser Particle Sizer ANALYSETTE 22 NanoTec has been used (see meas.no. 7042 on separate page).

Also a grinding with zirconium oxide for grinding bowl and balls is possible. Because of the smooth surface of bowl and balls, longer grinding times use to be needed compared to sintered corundum (see result 1).

After a total dry grinding time of 60 minutes, sample is starting to stick to bowl and balls. A longer dry grinding time is not recommended to achieve a better fineness. We recommend grinding in suspension (e.g. solvents for a faster evaporation) to improve the grinding result.

Fineness has been checked with our Laser Particle Sizer ANALYSETTE 22 NanoTec after a total dry grinding time of 60 minutes (see meas. no. 7092 on separate page).