Shredded electronic scrap

The presented sample use to be moistened and rusty. We don’t recommend grinding wet samples like this to prevent corrosion of bearings or grinding parts. We dried the sample previously (110 °C für 2 hours) to prevent corrosion (and easy cleaning the grinding chamber by vacuuming with a soft brush).

The desired task to grind the particles to < 0,1 mm as requested cannot been reached. Smaller sieve cassettes as 0,25 mm trapezoidal perforation are available on special request, but we only recommend such sieve cassette sizes for a grinding of very brittle samples like coal or coke. Also no other machine comes into question when sample uses to be ductile like this. For example, a planetary mill might deform small fragments to flakes which will be very thin, but still length up to 0,5-1 mm can be found.

We found several pieces inside the original sample, which use to be definitely too big for a usage with a cutting mill. In the following picture page which is attached to the report, you will find particles which use to be marked with a red square. Inside that square you find several screws with a head up to 8 mm Ø and a shaft of up to ~ 4 mm thickness, a zipper which is about 2 mm thick. Also some folded metal sheets with ~ 0,5 mm thickness which use to be very stable and inflexible. All those particles are possible candidates to produce cutouts on the cutting knives.

In worst case, such a big screw can damage several inserts or even the fixed knives within a few seconds. Even larger broken out pieces of an insert are able to damage further ones.

For this, we recommend using the disk milling rotor with indexable inserts and knives made of hardmetal tungsten carbide. Indexable inserts can be turned 3 times before they need to be replaced. A replacement of inserts or fixed knives can be performed on the customer’s side.

On the picture page, we placed an orange square over a pile of pieces which might be able to produce break outs on knives. It is possible that those particles can be fed without producing damages, but to be on the save side, we don’t recommend feeding such particles too.

The pile which is marked with a yellow-green square is made of glass or ceramics. Those particles will not produce break outs or significant damages, but glass and ceramic particles use to be very abrasive and will show a sanding effect to the grinding chamber. If possible, also avoid a feeding of such particles too.

The rest of sample use to be coated with plastic or is made of mainly thin and flexible wires, not ferrous metals or thin sheets. A grinding of such particles can be performed for sure.

We took about 200 grams of sorted sample (equal to right and middle right pile in the picture page) and ground the particles with our Universal Cutting Mill PULVERISETTE 19 (a Power Cutting Mill PULVERISETTE 25 as desired is not suitable for grinding < 2 mm with most samples).

We used the protected funnel to reduce exploration of fine metal dust. Nevertheless, still a tube of vacuum cleaner should be fixed next to the feeding funnel when the optional sample exhauster system with cyclone separator will not be used.

Within 5 minutes of grinding, an output of 135 g has been achieved. After a total of 7,5 minutes; 185 grams have been found inside the collecting vessel. After 10 minutes, we found 195 g of output. The grinding sound has been significantly reduces after 10 minutes because only a small rest of sample remained inside the grinding chamber. We stopped the machine after a total of 12 minutes of only found 1 gram of additional output. For this, 10 minutes of grinding should be fulfilling.

Afterwards, only a few particles use to lie loose on top of the sieve cassette. There are no new damages to the knives of our used disk milling rotor after this trial. A grinding of higher amounts should be possible.

We also fed 10 grams of ceramic and glass material which is shown in the yellow-green square of the pile of the picture page. After 20 seconds of grinding, an output of 6,3 g has been achieved. Grinding sound has been as smooth as shown by grinding the wired material. For this, we are sure that there will not been any damages when such particles will be fed.