Green alge (Haematococcus Pluvialis)

Planetary Micro Mill PULVERISETTE 7 classic line

main disk speed: 800 rpm

45 ml grinding bowl made of zirconium oxide (ZrO2)

+ 7x 15 mm ZrO2 grinding balls

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.

With temperature sensitive samples, grinding time can be lowered or pausing time can be raised. This is counting for the following trial as well.

In the beginning of the grinding trial, fineness use to become better rapidly. After ~ 30-60 minutes, grinding advantage became limited. For this, 5 hours have been necessary to reach d50 < 15µm.

We recommend using grinding balls of 15mm Ø for maximum 30 minutes grinding time and changing the balls afterwards to e.g. 1-3mm Ø for much faster total grinding time.

Planetary Mono Mill PULVERISETTE 6 classic line

main disk speed: 600 rpm

250 ml grinding bowl made of zirconium oxide (ZrO2)

+ 15x 20 mm Ø ZrO2 grinding balls

In this trial, 3 times as much sample has been ground. For this, fineness after 3 hours of grinding did not reach the desired d50 < 15µm.

Longer grinding times arestill possible, but as described in result 1, we recommend using the 20mm Ø grinding balls for 30-60min and changing the diameter afterwards to e.g. 1-3mm Ø.

Some further comments:

Usually we recommend using proper amount of water (or solvent) to achieve a motor oil like viscosity. Probably your kind of sample will show a better grinding result when viscosity might set a little higher (more pasty sample).

Also the usage of grinding balls and bowls made of sintered corundum can be beneficial in the beginning of a grinding trial with organic samples.