sodium waterglass (sodium silicate)

As desired, the sample has been ground with zirconium oxide as bowl and grinding ball material. This way, a discoloration of sample by abrasion will be hindered (grinding with metals for bowl or grinding ball material use to produce gray colored discolorations).

After a total dry grinding time of 40 minutes, the sample starts sticking to bowl and balls.

This uses to happen after the majority of particles reached a fineness of < 20-30 µm. Interacting forces between fine ground particles will become bigger as 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 will not be ground any further.

A longer dry grinding is not recommended.

A final fineness of d50 < 7,73 µm and d90 < 29,86 µm has been detected with our Laser Particle Sizer ANALYSETTE 22 Compact. The target of grinding 100 % < 50 µm has been reached. A further grinding in suspension (to eliminate interacting forces) is not necessary.