Barley (barleycorn)

Because of the request that sample should not been heated at all, we embrittled the sample before feeding in liquid nitrogen. By this operation, sample will not become hotter that room temperature.

Usually the sieve ring has to be placed inside the machine with its arrow mark pointing upwards. Then mean ground sample will be comminuted to a size which is about 50 % of the size of the trapezoidal openings. With 1 mm sieve ring, a d50 < 500 µm is estimated.

When the arrow mark will point downwards, resulting particles will be ground even finer.

The small sample amount has been fed and got ground within 30 seconds.

Sieve ring and rotor do net get clogged with sample; even higher amounts of sample might be grindable.

Before this trial, the grains, balls and grinding bowl have been placed in liquid nitrogen for embrittlement. The gasket to seal the bowl wasn’t mounted and will not mount in the grinding trial later on (it might embrittle and can be damaged).

After a minute of embrittlement, bowl, grinding balls and sample have been taken out of the liquid nitrogen and the bowl with its filling got assembled and has been fixed to the Mini-Mill PULVERISETTE 23.

After 1 minute of grinding, all grains have been comminuted to < 200 µm.

Longer grinding time might still be possible.