salt with iodine

After 4 minutes of dry grinding, sample starts sticking stronger to bowl and balls.

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.

We determined the fineness by sieving an aliquot with our Vibratory Sieve Shaker ANALYSETTE 3 Pro and a 100µm mesh test sieve. About 85% of sample use to be smaller as 100µm (as desired).

A better dry grinding result can be achieved separation of desired fineness by sieving or sifting and further grinding of coarse sample until sticking occurs again.

Also a grinding in suspension (e.g. in alcohol) is plausible to achieve a 100% < 100µm result.

Comments of result 1 use to count for this grinding trial too.

After 2 minutes, achieved fineness caused a sticking of sample. Because of zirconium oxides higher density (compared to agate in result 1), this use to be a typical result.

By sieving an aliquot, a fineness of 88,8% < 100µm has been detected.

If sample uses to be moisten, a pre drying might be able to improve a dry grinding result. Also a grinding in suspension is possible to achieve a 100% result.

A grinding of 35g of sample with Variable Speed Rotor Mill PULVERISETTE 14 and the used 120µm sieve ring is not possible. After 28g of sample have been fed, sieve ring became closed with sample. A cleaning step is required (e.g. with a wired brush).

The achieved fineness has been tested with our Vibratory Sieve Shaker ANALYSETTE 3 Pro and a test sieve of 100µm mesh. About 99,4% of sample is able passing the test sieve.

Probably a better result (less sticking of sample) will occur when sample will be dried previously to remove moisture.