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05.10.2018  |  10082x
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NETZSCH LabPilotPlant with High-efficiency Fine Classifier m-Class
NETZSCH LabPilotPlant with High-efficiency Fine Classifier m-Class

Grinding and Classifying of Rare Earth Powders

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 obtained. A decisive advantage of the m-Jet compared to fluidized bed jet mills or target mills is the possibility of the automatic rejection of components which are difficult to grind. This requires only a few seconds and takes place during operation of the m-Jet. The overpressure in the mill ensures that components which are difficult to grind are transported into the filter. In this way, there is absolutely no problem caused by contamination of the product-conveying piping with coarse product particles and/or these problematic components. Furthermore, due to the differences in design, the product content during the grinding phase of an m-Jet is 20 to 25 times lower than that of a fluidized bed jet mill with the same amount of grinding gas. At the same time, this results in an extremely low product loss during product change due to the smaller volume of the grinding chamber. In addition to this, practically no fluctuations in throughput capacity and especially in the particle size distribution occur during start and stop of the plant. Furthermore, a selective grinding of individual alloy components does not take place.

The dynamic air classifier integrated in the m-Jet ensures a clearly defined maximum particle size of the ground product. In a subsequent step, undesirable finest particles are separated out by classifying the ground material with a NETZSCH High-efficiency Fine Classifier m-Class to obtain a powder with a defined, narrow particle size distribution. The higher grade of the raw materials produced using the mentioned process is reflected in the quality of the magnets manufactured with them. Compared to magnets made of ground powder only, rare earth magnets made of classified powder have a higher coercive field strength and significantly improved knee-field strength.

Company information

Netzsch Lohnmahltechnik GmbH
Netzsch Lohnmahltechnik GmbH
Netzsch Lohnmahltechnik GmbH is a service company with locations in Bobingen (company headquarters and administration) as well as the facility in Hanau and is part of the Business Unit Grinding & Dispersing in the Netzsch Group. As a leading international company, we also offer toll services for the wet grinding sector, which are performed at our location in Selb. We work with an ultra-modern and diversified selection of machinery for mechanical processing of a variety of materials. In addition to a pilot plant for product development and processing of small quantities, our state-of-the-art laboratories offer additional technologies for diverse analyses and quality assurance. We are mindful of providing the highest quality in all processes. The service we provide for your application also includes eminently important factors such as packaging, labeling and warehouse logistics, which our specialists adapt to your requirements with speed and flexibility. Hazardous materials are handled with exceptional professional responsibility. We also offer contract services in the area of wet grinding and dispersion of powders in liquids. Challenge us – we`ll work closely with you to find a customized solution. Whether the finest classification, demanding grinding tasks, or the related analyses – we always offer you a quick and professional solution. This allows you, for example, to bridge temporary capacity bottlenecks, introduce new products or outsource your own production without the investment risk. With our two locations in Bobingen and Hanau, we are always nearby and, as a company with world-leading processing technology, we offer you everything from one source – ISO certified and Made in Germany. See for yourself. We combine tradition, know-how and pioneering products in excellent quality and technology.
Last update: 06.06.2023

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