Al2O3 (Tabularna Glinica)

After the first 3 minutes of grinding, particle size distribution has been checked with our Laser Particle Sizer ANALYSETTE 22. A d50 < 40µm has been achieved.

Sample has been pre ground with 30mm Ø grinding balls, we recommend changing the grinding balls to 15x 20mm Ø to reach desired fineness.

Because sample does not start sticking yet, longer dry grinding times are still possible (see result 2).

After pre grinding with 30mm Ø grinding balls, used in result 1 has been exchanged against 20mm Ø grinding balls for an optimum grinding result. This ball size will be capable to reach desired fineness.

After a total dry grinding time of 10 minutes, sample starts sticking to bowls and balls.

This usually happens 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 become compressed by the used grinding balls. These clusters of particles also contain bigger particles which will not be ground any further.

A longer dry grinding time is not recommended.

Particle size has been checked with our Laser Particle Sizer ANALYSETTE 22. A d50 < 9µm has been found.

To achieve the desired fineness, a grinding in suspension is required (see result 3).

Because of sticking of sample in result 2, we added 40 ml of water to proceed grinding.

An optimum grinding result will be achieved, when slurry shows motor oil like viscosity.

To avoid over pressure, we ground the sample in steps of 5 minutes, followed by a programmed pausing time of 10 minutes. After several cycles, the outside temperature of the bowl should be checked (remain below 80°C); grinding time or programmed pausing time might be readjusted afterwards.

After a total grinding time of 20 minutes, desired fineness of d50 < 5 µm has been achieved. We determined a d50 < 4,4 µm with a d95 < 22,7 µm.

Longer grinding times or a change of grinding ball size (always minimum 20x bigger as max. particle size) are still possible to achieve a better fineness.