magnesium oxide (sintered - MgO)

After 3 minutes of dry grinding, sample starts sticking stronger to puck and rings. A longer dry grinding time is not recommended.

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.

To determine the achieved fineness, we sieved an aliquot with our Vibratory Sieve Shaker ANALYSETTE 3 Pro and the proper test sieve. About 95% of sample is < 63µm.

To improve the grinding result, a separation of desired fraction can be done by sieving or sifting and the coarse fraction can be ground once more until sticking will occur again.

Also a grinding in suspension (to eliminate sticking forces with e.g. alcohol for fast evaporation) will be possible for grinding 100 % < 63µm.

**after 5 minutes grinding time the sample starts sticking/ one big particle could not be ground because the feeding size was too big: We suggest to precrush the sample with our jaw crusher pulverisette 1