Alpine systems have found a
niche for themselves not only in processes employed to
manufacture rare earth powders for magnets, but also for
the production of classic hard and soft ferrite powder.
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The Alpine Fluidised Bed Opposed Jet Mills AFG-R (patented
technology) are used especially for neodymium-iron-boron alloys.
With a downstream Turboplex air classifier, end-product finenesses
of between 1.5 and 4.5 µm measured with a FSSS are possible.
This means a steeper particle size distribution and thus a
higher field intensity. The flowchart below shows the process
sequence of an actual system.
Legend
1 = Compressor
2 = Low pressure tank
3 = High pressure tank
4 = O2-Measuring
system
5 = Feed bin
6 = Dosing device
7 = Flap valve
8 = Fluidised bed opposed jet mill AFG
9 = Turboplex classifier ATP
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10 = Cyclone
11 = Autom. filter
12 = Control cabinet
A = Feed product
B = End product
C = Dust
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After grinding and classifying, the
end product is collected in a cyclone and dedusted. A sonic
system prevents forming of deposits in the cyclone. The cyclone
efficiency is over 98%.
The system is operated with nitrogen. The oxygen content is
less than 10 ppm, which is necessary because the product must
not be allowed to oxidise if a qualitatively high field strength
of the magnets is to be guaranteed at the end of the process.
Special cases call for the system to be operated with argon
gas, whereby the system naturally has to be configured accordingly.
System with ALPINE Fluidised Bed Opposed Jet Mill 200 AFG-R
with downstream Turboplex Ultrafine Classifier 100 ATP.
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