sunflower seeds

Sunflower seeds use to contain a high amount of fat and oil. For this, sample tends to stick very fast. By embrittlement with liquid nitrogen (N2), sample might be grindable for a short moment.

In our first trial, 50g of sample have been placed inside a pot of liquid nitrogen for one minute. Afterwards, sample has been fed spoon wise to the feeding funnel of the Universal Cutting Mill PULVERISETTE 19. After ~ ½ of sample has been fed, grinding sound already indicates that pieces of sample did not pass the sieve cassette fast enough and fatty particles might start melting again. After totally 90 seconds, the whole sample amount has been fed.

We found an output of only 21g of ground sample. A high amount of sample started smelting in front of the knives and use to close the sieve cassettes openings.

Cleaning can be done rapidly with a vacuum cleaner and a brush. Sieve cassette can be freed of residues by using a wired brush.

A grinding of 500g as desired is not possible this way.

Probably active sample exhauster system with cyclone separator will be able to remove fine ground sample before a melting will happen.

Additionally, a sieve cassette with 0,75mm trapezoidal perforation will be used instead of one with only 0,5mm trapezoidal openings.

Sample use to behave like in result 1, higher amount of oily sample is sticking in front of the fixed knives and a few openings became closed with sample.

This kind of equipment combination is not useful for grinding sunflower seeds.

In our last trail with Universal Cutting Mill PULVERISETTE 19, the sample will be fed slowly.

Also a 1,0mm sieve cassette has been used in this trial.

Output uses to raise (22,5g of 25g), only 2,5g of sample use to stick lightly in front of the fixed knives of the grinding chamber.

For a grinding of higher amounts (e.g. 500g), we are guessing that a cleaning step after 100-150g of sample might be required.

Probably with higher airflow of the cyclone separator, the sample will reach room temperature faster and starts melting earlier. Eventually it might be helpful not using the active cyclone system.

Also the Variable Speed Rotor Mill PULVERISETTE 14 will be capable for grinding higher amounts by using the accessories for grinding large quantities (filter bag system); also the sample exhauster system with cyclone separator can be used with the PULVERISETTE 14.

After embrittlement, sample has been fed continuously. All sample has been ground within 90 seconds. Rotor and sieve ring use to remain free of sample. A grinding of higher amounts is still possible.

Our second trail with PULVERISETTE 14 has been aborted after ~ 60 seconds. Grinding sound indicates that trapezoidal openings of the sieve ring might be blocked with sample.

Only a small amount of sample has been found inside of the collecting pan. The majority of sample has been compressed between rotor and sieve ring. A grinding is not possible with this setting.

A sieve ring with 1,0mm trapezoidal perforation has been used for our last trial. Remaining sample amount has been used completely for our last test.

After 90 seconds, all sample has been ground. As seen on the photo below, a bit of the sample use to stick on the inside of the sieve ring and starts covering its openings. At least after 100g of sample has been ground, also a cleaning step will be required again.

This combination is not capable for a grinding of up to 500g in one batch. Only trail 4 will show a good result (for a grinding of 0,5kg -1,0kg, we recommend using the accessories for grinding large quantities).