Straw (Cereals waste particles)

100 g of sample can be ground with our Cutting Mill PULVERISETTE 15 without problems. With the properly filled grinding chamber, an maximum output of 48 g can be achieved per minute. After the second minute, output rose by 13 g (total 61 g). After the third minute of grinding, additional 6 g of sample have been found in the collecting vessel (completely 67 g).

We aborted the grinding process after 5 minutes with a total output of 73 g. The remaining sample inside the grinding chamber is just spinning with the airflow and does not get cut that properly.

We are guessing that a constant feeding of higher amounts might be possible. We are expecting that a higher amount of sample will heat up inside the grinding chamber constantly, but with such lightweight sample, we don’t expect that sample will become carbonized. Probably the knives with their sharp edge might get dull much faster (compared to a V-cutting rotor of a PULVERISETTE 19 Universal Cutting Mill with not that sharp cutting angle).

The second sample has been used with our Universal Cutting Mill PULVERISETTE 19. We are guessing that a grinding with the optional cyclone will achieve similar results compared to result 1.

With the Universal Cutting Mill PULVERISETTE 19, also the sample exhauster system with cyclone separator can be mounted for a rapid grinding of higher amounts. With its airflow (2800 liters of air per minute), the sample will be chilled additionally. Also sample will be blown out of the grinding chamber when it is able to pass the used sieve cassette.

With the cyclone, we achieved an output of 100 g / minute. After ~ 90 seconds, it grinding sound indicates that the majority of sample has been ground. After a total grinding time of 2 minutes, only a minimum residue can be found loose on top of the sieve cassette.

A grinding of higher amounts should be possible without any problems.

With a Variable Speed Rotor Mill PULVERISETTE 14, more than the half of sample will get ground to the half of the used sieve ring openings. For this, with a 0,25 mm sieve ring, over 50 % might get ground to < 125 µm.

With our third trial, we wanted to check the grindability of sample by the impact force and shearing force which use to be the principle of grinding with a Variable Speed Rotor Mill.

The 30 g of sample have been fed and ground within 90 seconds. As shown on the photo, the resulting particles use to be way finer that the results of trial 1 & 2.

Rotor and sieve ring are only minimal polluted, cleaning can be done rapidly by vacuuming with a soft brush.

For a grinding of higher amounts, we recommend using the accessories for grinding large quantities (with sample amounts > 50 g - see result 4), or the sample exhauster system with cyclone separator (for much higher sample amounts like e.g. > 500 g).

In our last trial, we used the remaining sample to check the grindability of sample with the accessories for grinding large quantities.

The 85 g of sample have been ground within 70 seconds. With the used 0,5 mm sieve ring, the ground sample still appears finer as the results of trials 1 & 2 which have been achieved with cutting mills.

With this setting, rotor and sieve ring are still minimal polluted with fine dust. A grinding of higher amounts is still possible. Also the backside of the rotor is free of higher dust amounts. We are guessing that a grinding of up to 500 g of sample will be possible without problems.