Icing Sugar

A dry grinding of your kind of sample is not possible to d90 < 10µm. When 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.

For this, we recommend using isopropyl alcohol (IPA) for grinding.

To avoid overpressure, 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 totally 60 minutes of grinding, fineness has been checked with our Laser Particle Sizer ANALYSETTE 22. About 84,3% use to show a fineness < 10µm.

A longer grinding time is still possible to reach the desired endfineness. Also a change of ball diameter after e.g. 15 minutes to 5mm Ø might be possible to achieve the desired endfineness much faster.

Comments of result 1 also use to count for this trial.

In our second trial, we only used 100g of sample and have chosen zirconium oxide as material for grinding bowl and grinding balls. With its higher density, grinding success should occur much faster.

After 30 minutes of grinding, about 84,4% use to be < 10µm. After 60 minutes, d90 < 10µm has been reached. After 120 minutes of grinding, even 97,3% use to be < 10µm. We are guessing that a longer grinding time will be able to achieve 100% < 10µm without a change of ball diameter.

For a faster grinding result, we recommend using the 20mm Ø balls for maximum 15-30minutes and changing the balls to 3mm Ø until the desired fineness will be reached. We are guessing that within totally 60 minutes, all sample should be ground to < 10µm that way.