April 4th, 2022
Netzsch is offering the ProPhi, a new pre-grinding unit. A pre-mill, the company says, manages grinding coarse feed material that is difficult to handle in a standard mill. Pre-dispersion of agglomerates, which is usually done batchwise or continuously in intensive mixing units, can also be carried out there.
This requires upstream introduction of the solids into the liquid phase. A challenge in the continuous preparation of coarse suspensions is their tendency towards sedimentation, which can be solved by a correspondingly high flow rate or high product throughput.
The ProPhi 20 is a disk agitator bead mill modified for coarse grinding with high throughput, with a grinding chamber volume of approximately 20 liters. In the peripheral speed range of 8 – 12 m/second, a product throughput of up to 25 cubic meters per hr. can be achieved with this machine size. The diameter of the grinding media used typically ranges from 2.0 to 4.0 mm.
During development of the pre-grinding unit, a disc agitator was selected as the basis because, compared to a pin agitator, the same net power input yields almost double the grinding chamber volume. This means that significantly more grinding body contacts and a larger cooling surface are available for grinding. Essential for achieving the extremely high product throughput rates is a highly efficient separation system, which allows the grinding media to be left evenly distributed in the grinding chamber with low counterpressures.
The ProPhi pre-grinding unit can be supplied in different machine sizes depending on the batch size. Tests with different products have shown, Netzsch says, that process control with the ProPhi pre-grinding unit can reduce specific energy requirement by more than 50 percent compared to using classic pre-dispersion systems. At the same time, this means a multiplication of production capacity.