Clay

With a start size about 5 cm (long and wide), typically a pre-crushing would be required before any other type of mill from Fritsch might be used. This can be done manually, or with our Jaw Crusher PULVERISETTE 1 (no matter if premium line or classic line would be used).

For demonstration, we used 300 grams of the dry clay quality for comminution with Jaw Crusher PULVERISETTE 1 premium line.

Steel jaws were used and a gap setting of 0,3 mm was set. The prepared pieces of clay were added into feeding funnel and slide into the grinding chamber without problems.

The grinding sound was typical for a clay sample. The sound vanished rapidly after ~ 90 seconds. Typically, a lot of clay particles are already smaller than 4 µm and tend to stick to available surfaces, when such a sample would be ground in dry form. We found a few traces inside the grinding chamber, where the smallest gap was formed.

The sample output contained a lot of fine sample fragments and a few small fragments of clay, which were already compressed again, by the moving crushing jaws (easy to break apart manually).

Such a result was typical when a dry clay sample was comminuted. The wet quality of clay could not be ground this way. Those types of sample will only become deformed and stay attached to all surfaces where force was applied. For the wet quality of clay, a previous drying is obligate.

For a desired fineness of < 1 mm, plenty of machines could be used. It is possible to combine a Jaw Crusher PULVERISETTE 1 with our Disk Mill PULVERISETTE 13 (and a special stand), to comminute the samples in one step.

Also a Mortar Grinder or Planetary Mono Mill might come into question to grind the sample in smaller batches.

For a comminution of 500 grams directly, we would recommend using a Cross Beater Mill PULVERISETTE 16. This type of mill is hammering down a sample rapidly in one batch.

320 grams of original sample material was pre crushed manually (< 2 cm length) and was fed continuously into the feeding funnel. It took only 90 seconds until all fragments were fed and ground and the grinding sound vanished.

A lot of sample was ground much finer, than a 1 mm bottom sieve would allow to pass. Also here, as expected, a lot of fine sample dust was compressed into the ribs of the grinding chamber.

For a rapid cleaning, the grinding set (rotor and chamber insert) can be removed without tools. We used hot water for an intensive cleaning. After cleaning (which took about 5 minutes), the grinding set was dried quickly to prevent corrosion. Only the front door inlay requires manual cleaning. A wired brush was used for the front door inlay. We would recommend to comminute about 520 grams of sample to achieve an output of ~ 500 grams.

We would recommend using the insert made of stainless steel for this application.

As mentioned in result one, only the dry clay sample can be used. The moistened quality will stuck on all available surfaces and would clog the trapezoidal perforations rapidly.