The comminution of the various plastics and metals found in a typical cellular telephone in samples for RoHS/WEEE analysis requires a considered approach
In the materials used for the construction of a cell phone, the whole spectrum of hard-tough to hard-brittle up to soft, tough-elastic materials is found.
These include metals, ceramic parts, and various plastics.
Whereas the hard-brittle materials are easily ground with impact energy, the comminution of tough-elastic materials is only achieved with cutting force.
Tough-elastic materials may be embrittled with liquid nitrogen and then ground with impact force.
The power cutting mill Pulverisette 25 was chosen as the first level of comminution of a complete cell phone.
Once reduced to 10mm the vibrating cup mill Pulverisette 9 was supposed to complete the rest.
This experiment was unsuccessful.
Therefore the Pulverisette 25 with a 4mm sieve was used again.
For the next level, the universal cutting mill Pulverisette 19 was chosen.
With cutting tools made of hard metal tungsten carbide the remainder was comminuted down to 1mm.
An attempt to achieve even a finer powder by exchanging the sieve was unsuccessful.
That's why as the last level of comminution the variable speed rotor mill Pulverisette 14 with a 0.5mm sieve was utilised.
Good experiences of the comminution of single electronic components were made with the vibratory micro mill Pulverisette 0, embrittled with liquid nitrogen in the cyro-box.
