antracite coal

In our first trial, we ground half of sample with a gap setting of 0,3 mm. This way, all particles will get ground to < 0,3 mm in one dimension. It is still possible that particles with a length of > 0,5 mm can be found after grinding.

The complete sample amount has been ground within 3 minutes. Grinding disks and gap is only polluted with electrostatic charged dust which can be removed easily by vacuuming with a soft brush.

To determine the present particle size, we used a Vibratory Sieve Shaker ANALYSETTE 3 and test sieves of 400 µm and 315 µm mesh.

The following fractions have been found: 39,7 % > 400 µm; 14,8 % of sample in the desired range of 315 - 400 µm and already 45,5 % of sample which use to be < 315 µm.

Because of the high amount of particles > 400 µm, we recommend using a smaller gap setting (e.g. 0,2 mm – see result 2).

There is no significant increase of grinding speed for a comminution of sample with a gap setting of 0,2 mm. The grinding chamber has been empty after 3 minutes too.

Only electrostatic charged sample dust use to remain inside the grinding chamber. A grinding of higher amounts is still possible.

The following fractions have been determined by sieving: 15,3 % of sample use to be > 400 µm; 11,8 % are in the desired range of 315- 400 µm and 72,9 % of sample is able to pass the 315 µm test sieve.

To optimize the output of particles in the desired range, it is possible to grind the sample with a wider gap (e.g. 0,4-0,5 mm) and separate fine ground particles (e.g. by sieving or sifting). Afterwards, the coarse fraction can be fed a further time. By step wise proceeding like this, an output of up to 30-% in the desired range (315-400 µm) is plausible to achieve.