Graphite

The start size of sample was very large, to provide a long durability of fine sieve rings, we strongly recommend a pre grinding step of the graphite junks with a reinforced 2 mm trapezoidal perforated sieve ring.

We used the desired amount of 10 grams and fed the sample into the mill which was set to comminute with maximum speed (20.000 rpm). It took 20 seconds for feeding of sample. The grinding sound was typical and vanished instantly after the last fragment was fed. Only a bit of fine dust escaped the feeding funnel; the usage of one of our cyclone setups was not required for comminution.

No clogging of sieve ring perforations was observed. Even higher amounts of sample could be ground this way, too. The majority of ground sample material was significantly finer than a 2 mm perforated sieve ring would allow to pass.

Ground sample was brushed out and will be used for a second grinding step with result 2. Cleaning was performed rapidly by vacuuming with a soft brush.

Pre-ground sample of result 1 (< 2 mm) was used for this trial. We replaced the sieve ring of result 1 against a sieve ring with 0,2 mm trapezoidal perforations for fine grinding.

The ~ 10 g of pre-ground sample was slowly fed into the feeding funnel. Also, with this trial, the sound of grinding was typical. As found in result one, a bit of fine ground sample dust escaped the feeding funnel when a closed collecting vessel was used.

It took 2:40 minutes until all sample was fed and ground. After grinding, trapezoidal perforations appeared to be fee; only fine ground sample dust stuck by electrostatic charge (or other active forces) on available surfaces.

We brushed off the ground sample and checked the achieved level of fineness by static light scattering. With our Laser Particle Sizer ANALYSETTE 22 NeXT Nano, we determined 100 % < 50 µm with d90 < 23,5 µm fineness.

For an intensive cleaning, all grinding parts were disassembled and washed with warm water.