Ferro tungsten

With a start size of up to 2 cm, a pre grinding step is necessary. For this, we ground the complete sample with our Jaw Crusher PULVERISETTE 1 Model I.

Because of the hardness of sample, we recommend using jaws made of hardmetal tungsten carbide to avoid higher abrasion.

After 40 seconds of grinding, the complete sample amount of 680 g has been ground to < 8 mm (max. length). Majority of particles use to be < 5 mm.

A grinding of higher amounts is still possible.

Because of the start size, we used 30 mm Ø grinding balls for comminution. After 5 minutes, size of particles use to be < 1mm, we changed the grinding balls to 20 mm Ø for a faster grinding result.

After 30 minutes of grinding, sample starts sticking to bowl and balls. This uses to happen after the majority of particles reached a fineness of < 20-30 µm. Interacting forces between fine ground particles will become bigger as their own g-force. Therefore, particles will stick to each other and become compressed by the used grinding balls. These clusters of particles also contain bigger particles which will not be ground any further.

Present fineness has been determined by sieving an aliquot of ground sample with a Vibratory Sieve Shaker ANALYSETTE 3 Pro and a test sieve with 120 µm mesh. Already 95 % use to be < 120 µm.

A longer dry grinding is not recommended. To improve the dry grinding result, small particles can be separated by sieving or sifting (classifying) and proceed grinding the coarse fraction.

Also a grinding in suspension is possible to achieve 100 % < 120 µm.