6.4.5 Weight of the balls (type of material)
A higher mass (specific weight) of the grinding balls accelerates grinding.
(see table in
Ä
Chapter 6.1 „Choice of grinding bowls and grinding
balls“ on page 28).
6.4.6 Dry grinding
Below a particle size of approx. 20 µm, the surface forces prevail. The
grinding stock begins to stick.
Additional dry comminution can be achieved by adding surface-active
substances to the material to be ground.
Examples (maximum amount to be added in mass%)
n
Stearic acid 2-3%
n
Aerosil (fine-particle silicic acid) 0.5 - 2%
n
Quartz sand ~ 2%
n
Glass powder ~ 2%
n
Glycol (Ethylene glycol) ~ 0.1 - 0.5 % (
≙
5 - 25 droplets)
n
Triethanolamine ~ 0.1 - 0.5 %
6.4.7 Wet grinding (grinding in a suspension)
DANGER!
Explosion hazard! Ignition hazard!
The device is not explosion-protected. If flammable liq-
uids are used, make sure that the heat developing in
the grinding bowl does not reach the solvent's boiling
point. Program appropriate cooling phases. If the
vapour pressure is too high, vapours may escape and
ignite.
If it can be avoided, we recommend using non-flam-
mable liquids or liquids with a high boiling point. The
boiling point should be above 80 °C and above 100 °C
for a long grinding duration.
During the transition to grinding in suspension, you can add a liquid aux-
iliary agent with high boiling point and low vapour pressure, e.g. water,
white spirits (boiling point 100 - 140°C), or alcohols with a high boiling
point (e.g. isopropanol)
We recommend that you only use so much liquid that the suspension has
the same consistency as motor oil. With this viscosity the best results can
be achieved in most cases.
Using the device
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