Artificial Sweetener Tablets

For about 1 gram of sample, we used a 10 ml grinding bowl. We estimated that even 10 mm Ø grinding balls can be used for comminution. If the sample would be too hard, also 15 mm Ø grinding balls could be used for comminution.

For higher amounts of sample, 15 ml grinding bowl could be used. We estimate that up to 2,5 grams of sample could be ground with the larger bowl.

With just 30 seconds of grinding at maximum speed (50 Hz), the tablets were ground to a fine powder which started sticking to bowl and grinding balls. Also the bulk volume of the sample rose and filled the bottom half (together with grinding balls) almost completely.

Sticking of sample happens after the majority of particles reached a fineness of < 20-30 µm. Interacting forces between fine ground particles become larger than 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 are not ground any further. A longer dry grinding of sample is not recommended.

To avoid a sticking of particles and achieve a better fineness, we recommend a comminution in suspension. Also, anti-sticking agents (e.g. Aerosil or a couple of droplets of e.g. methanol) can delay a sticking somehow.