6.9.2 Recommended Grinding Jar Filling
Recommended number of grinding balls
In addition to the instrument settings, the filling level of the grinding jar is also of crucial
importance for a successful grinding process in the High Energy Ball Mill of Retsch GmbH.
When grinding bulk materials, the grinding jar filling should consist of approximately one
third of sample and one third of ball quantity. The remaining third is the free grinding jar
volume, which is required for the movement of the balls.
If an increase or decrease in sample volume is to be expected during the grinding process, the
amount of sample can be adjusted within the range listed in the table. Thus, e.g. for voluminous
materials such as wool, leaves, grasses and similar, a material filling level of 70 – 80 % is
necessary. For wet grinding with grinding balls < 3 mm, the ball charge should be 60 % of the
grinding jar volume.
Cryogenic grinding
Grinding with liquid nitrogen (LN
2
) or dry ice
− When grinding with liquid nitrogen or dry ice, breakage of the grinding set
and damage to the device can occur!
• Grinding with liquid nitrogen or dry ice is not permitted!
6.9.3 Recommended Speeds
The following speed restrictions apply to grinding balls larger than or equal to 10 mm:
6.10 Inserting the Grinding Jar
Strong vibrations and loud noise
Uneven loading
− The device can generate particularly strong vibrations and loud noise if
loaded unevenly.
• Always insert two grinding jars of equal size, even if you only want
to grind one sample. In this case leave the second grinding jar
empty (no grinding balls, no sample material)!
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