TANTALUM

The amount of the presented sample (only 30 grams; two nuggets of ~ 30 mm length) is slightly less to estimate the required grinding time for up to one kilogram of sample. Eventually, a larger output size could be difficult to estimate. With the jaw crusher PULVERISETTE 1 model I, fragments up to 60 mm long can be fed. With a jaw crusher Model II, fragments up to 95 mm long can be fed.

Our jaw crusher was equipped with crushing plates made of steel; depending on the hardness of the sample, the using of crushing plates made of hard metal tungsten carbide is recommended. The two nuggets were fed to our Model I with the smallest gap setting (0.3 mm). The grinding noise was typical (not too hard) and after less than two seconds the grinding noise disappeared completely. No significant residues were found in the grinding chamber. Certainly, even larger sample quantities can be ground in this way. The cleaning was done quickly by vacuuming with a soft brush.

Due to the working principle, the smallest gap of 0.3 mm opens to a width of ~ 2 mm during operation. Only one dimension has to be maintained so that the supplied sample can pass through the grinding chamber. With this sample we found a lot of particles of about 2-4 mm inside the collecting vessel and a few fragments up to ~ 7 mm length and ~ 2 mm thickness. This was a typical grinding result for brittle samples ground with our jaw crushers.

In order to achieve a fineness of < 1 mm, we recommend the use of a Disk Mill PULVERISETTE 13. The feed size of the sample must be < 2 cm; therefore, the sample was pre-crushed with the Jaw Crusher PULVERISETTE 1 model I (premium line) (see test result 01).

In order to minimize the heating and mechanical load of a sample and to optimize the service life of the grinding equipment, we recommend to grind only as fine as necessary, but not as fine as possible.

By the first gap setting of 0.5 mm, we fed the pre-crushed sample completely and after 20 seconds the grinding noise disappeared. During this first step, many particles > 1 mm were still found inside the collecting vessel. We programmed a gap setting of 0.2 mm and fed the sample a second time. This grinding step took another 10 seconds until the grinding noise began to fade away. With a gap setting of 0.2 mm, we did not find any particles that were significantly longer than 1 mm. With the used jaw crusher PULVERISETTE 1 model I premium line, a gap between the grinding discs of up to 0.05 mm can be adjusted, in order to optimize the output size.

The grinding noise of the fed sample was not hard; the residues were mainly in the feed hopper or were deposited by electrostatic charge. Cleaning was carried out quickly by vacuuming with a soft brush.

Because of the limited sample quantity, we cannot verify the required grinding time for up to 1 kg, which should be ground to < 1 mm. Please keep in mind that the grinding devices can heat up due during the grinding process if larger sample quantities should be ground. Base elements can become much more reactive if such samples are ground finer and heating begins.