Manganese Ore

The ~ 8 cm long piece of manganese ore was pre crushed with our Jaw Crusher PULVERISETTE 1 Model I (premium line). With the smallest gap setting of 0.3 mm, the gap will open up > 2 mm with standard kinematics.

This setup is useful to pre crush brittle sample to mainly < 3x8 mm (always depending on sample properties). We fed the ~ 207 gram heavy piece into the feeding funnel and the grinding sound vanished rapidly, within ~ 10 seconds.

The majority of sample was comminuted as expected. A few smaller fragments were found with ~ 10 mm length for this sample. There was no significant clogging or sticking of sample, surely even higher amounts of sample can be pre crushed this way, too. Cleaning was performed rapidly by vacuuming with a soft brush.

After pre-crushing the sample with our PULVERISETTE 1, the sample was fed into our Disk Mill PULVERISETTE 13 (premium line) for this trial. The first ~ 105 grams of pre-crushed sample was fed into the feeding funnel completely. The machine was programmed to 0,15 mm gap setting. With a 0,15-0,25 mm gap setting, we estimate that a higher ratio of 300-355 µm particles will be found.

The grinding sound stopped after 30 seconds; the grinding process was aborted after 50 seconds. Some sample was on the fixed grinding disc and was brushed into the grinding chamber to be collected as well. About 100 grams of ground sample was packed and will be returned. Without a cleaning step, the second fraction of sample was fed and ground with a gap setting of 0,25 mm (see result 3).

The second half of the sample was comminuted by us with a gap setting of 0.25 mm. The sample was quickly fed via the feed hopper and was almost completely comminuted after approx. 25 seconds. The grinding noise decreased only slowly towards the end and we interrupted the grinding process after a total of 40 seconds.

95 g of 100 g could be packed from the collecting vessel. Cleaning of the grinding chamber was done quickly, using a brush and vacuum cleaner.

We do not recommend using the returned samples for subsequent analysis. The mill in our laboratory is not equipped with an optional plastic coating, and the cast iron housing can be a major source of cross-contamination. Many different samples have already been ground in our laboratory (e.g. elemental cobalt and silver in the past week) and certainly traces of a previously ground sample can still be found with a sufficiently sensitive analysis method.

To optimize the output of the desired fraction, it is possible to start with a coarser gap setting and separate the desired fraction e.g. by sieving or sifting. The coarse fraction can be fed in again with a slightly reduced gap setting and ground again. In this way, the narrow fraction can be enriched by particles between 300-355 µm and thus sample losses can be minimized. To find the optimal gap setting and sieving steps, several tests may be necessary.