electronic waste

For card board waste like this, we recommend using the rotor with indexable knives made of hardmetal tungsten carbide for a much longer durability.

By using the protected funnel with sample pusher, dust exposition during grinding will be reduced (compared with standard funnel). Also the tube of a vacuum cleaner can be placed next to the funnel to reduce exposition.

300 g of sample (~ 450 ml) have been fed within 2:30 minutes. After 3 minutes of grinding, an output of 282 g have been found. A bit of sample use to stick below the sieve cassette by electrostatic charge. The rest of sample use to be lost because of formation of fine dust, or will remain as residue inside of the grinding chamber.

After opening of the grinding chamber, only a small amount of sample use to lay loose on top of the sieve cassette. A bit of sample use to loose in front of the fixed knives. Rotor temperature use to be about 40 °C after grinding, only temperature sensitive sample will hinder a grinding of much higher amounts.

By using the optional sample exhauster system with cyclone separator, sample inside of the grinding chamber will kept chilled by the air flow of ~ 2800 L/min. Also grinding speed will be improved because fine ground sample will be sucked out of the grinding chamber when it will be able to pass the sieve cassettes openings. No dust can escape by the feeding funnel too.

In this trial, we want to show the grinding result with 0,25 mm trapezoidal perforated sieve cassette in combination with the cyclone separator. Smaller sieve openings (< 200 µm - as desired) are not recommended for such a kind of sample, because the space between the rotor knives and the fixed knives use to be in that range. Smaller sieves might only be suitable for a grinding of very brittle samples (like e.g. coal).

By using the cyclone separator, sample will be kept chilled, also fine sample dust will be removed by the cyclone separator too (with Hepa-filter element to prevent dust exploration).

With the 0,25 mm sieve, sample will take much longer to be ground. After 3 minutes, an output of 213 g has been found. After a total of 5 minutes, 350 g have been ground. Output rose to 375 g after 6 minutes. After 7 minutes, only 2 g more have of output have been found. For this, we aborted grinding after a total of 7 minutes.

Still some sample use to remain loose on top of the sieve cassette. Sample and rotor remains close to room temperature. A grinding of higher amounts is still possible.

For a grinding of 1 – 2 kg of sample, we would recommend using the 0,5 mm sieve cassette in combination with the cyclone separator.

With hardmetal tungsten carbide, maximum 250 ml bowls can be used. For this, a maximum amount of ~ 75 g can be fed per batch. By using a Planetary Mill PULVERISETTE 5, up to 4 bowl fasteners can be used for a simultaneous grinding of ~300-350 g of sample.

After a total grinding time of 5 minutes, grinding has been aborted. Metal wires became flatten out by the impact force of the grinding balls; high amount of pieces have been ground to a fine powder.

The used 20 mm Ø grinding balls does not seem to have enough impact force for a comminution of several thick (> 1 mm) plastic pieces. Probably 30 mm Ø balls might be able grinding more of pieces.

Nevertheless, the observed flattening of metal particles will happen with bigger grinding balls as well.

For this, a comminution of ductile metal particles will not be possible by using a planetary mill.

We also found one screw with a head of ~ 2 mm height and a diameter of ~ 4 mm. We like to mention that a feeding of such thick metal particles will be able to damage the tungsten carbide knives and the grinding chamber of a PULVERISETTE 19!