sand

After a dry grinding time of 30s, sample starts sticking lightly to puck and grinding set.

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.

Achieved fineness has been determined by sieving with our Vibratory Sieve Shaker ANALYSETTE 3 Pro: after 30 seconds, about 96,3% of sample use to be < 63µm; 91,8% < 50µm.

After totally 1 minutes of grinding, sticking of sample became a little stronger. We don’t recommend to dry grind the sample any further. Achieved fineness became improved lightly with ~ 98,7% < 63µm and 95,7% < 50µm.

For an improvement of grinding result, desired fraction can be separated by sieving or sifting and coarse fraction can be ground until sticking occurs again. Also a grinding in suspension is plausible to achieve 100% < 63µm.

General comments of previous grinding result use to count for this trial too.

With our Planetary Mono Mill PULVERISETTE 6 classic line, sticking of sample does not occur that rapidly. After 1 minutes of grinding, sample became ground to fine powder with a fineness of ~ 73% < 63µm and 65% < 50µm. No sticking of sample use to be shown so far.

After 2 minutes of grinding, light sticking of sample to bowl and balls occurs. Fineness has been checked by sieving; about 92,1% < 63µm and 86,5% < 50µm have been detected.

After the third minute of grinding, a moderate sticking of sample will be shown. We don’t recommend a further dry grinding of sample.

A fineness of 95,4% < 63µm and 91,4% < 50µm has been detected.

To reach a fineness of 100% < 63µm, we recommend a grinding in suspension.