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The functional principle of the PMT spiral jet mill is as simple as elegant. The material is fed pneumatically to the mill and runs spirally through the milling chamber. Grinding media enters the area through the milling nozzles. Grinding media is either compressed air (3.5 to 15 bar and 240°C) or superheated steam (up to 24 bar and 400°C). The air stream fluidizes the material-bed and lifts as much particles as possible into the stream. Comminution is mainly based on shearing forces which result from velocity differences. The integrated dynamic classifier is capable to run at a maximum circumferential speed of 190 m/s. As soon as the particles reach a certain finess, they can pass the classifier to the final product. The fineness can be easily adjusted by variation of the classifier speed.

Functional filler demand special grinding technologies. Every day we experience an increasing technical demand from the filler industry. We respond to the change from ‘extender filler’ to ‘functional filler’ with the PMT spiral Jetmill. High classifier speed and special classifier geometry allow products with a fineness in the low micrometer range and, depending on the material, even below 1 µm. + Finest particle sizes (d50) + Exact top cut (d97) + Narrow particle size distribution + High aspect ratio + Improvement of functional properties + Up to 30 % less energy consumption with newest development + High grinding efficiency due to the closed grinding and classifying circuit + Easy adjustment of fineness by regulation of rotor speed + Possibility to remove impurities + Guaranteed operational reliability

Their Use in Enhancing Quality in the Manufacture of Magnets Neodymium-iron-boron-magnets (Nd-Fe-B) are so-called rare earth magnets distinguished by their very high energy densities. A decisive factor for the quality and properties of permanent magnets is a narrow particle size distribution with the lowest possible fraction of finest- (< 2 µm) and coarsest particles (> 8 µm). The NETZSCH company offers innovative solutions to this application problem with a patent pending grinding process with downstream classifying of rare earth powders. The design of this process led to the development of jet mills and ultra-fine classifiers with which sensitive Nd-Fe-B-compounds or other rare earth alloys can be ground reliably to fine powders under inert gas operation giving a narrow particle size distribution and defined upper particle size limit with reproducible results. With NETZSCH m-Jet, a combination of a spiral jet mill with a dynamic air classifier, highest reproducible finenesses independent of the load in the gas jets are