As ALPINE launched the AFG fluidised bed opposed jet mill onto the market in 1981, it succeeded in revolutionising jet milling. Since then, over 1,000 machines have been sold for a wide diversity of applications.
In jet milling, comminution is exclusively the result of interparticle collision in the gas jets. And because there are no machine components in the grinding zone, neither machine wear nor product contamination occurs. This is why jet milling is often used when contamination-free products are required.
Jet milling is suitable for any material hardness value: from Mohs' hardness 1 (talc) to Mohs' hardness 10 (diamonds).
Jet mills are impact mills which are used to achieve maximum fineness values at maximum product purity. Such particle sizes can only be obtained in connection with an air classifying step. Spiral jet mills have a static air classifier integrated into the mill housing, whereas fluidised bed opposed jet mills are equipped with a dynamic deflector-wheel classifier.
The fineness is set as a function of the classifying wheel speed. All-important is a high product loading of the nozzle jets in order to achieve a high concentration of particles and thus high impact probabilities. The patented Megajet® nozzles were developed with this in mind. They consist of four small nozzles which as a result of their close proximity generate an underpressure at their common centre, and thus draw particles from the fluidised bed direct into the centre of the nozzle jet. The product level in the machine is controlled by means of load cells or by monitoring the current loading of the classifier drive.
Even difficult products can be processed efficiently with the AFG jet mills.
- Heat-sensitive materials such as toner, resin, wax, fat, ion exchangers, plant protectors, dyestuffs and pigments
- Hard and abrasive materials such as silicon carbide, zircon sand, corundum, glass frits, aluminium oxide, metallic compounds
- Highly pure materials where the requirement is contamination-free processing such as fluorescent powders, silica gel, silica, special metals, ceramic raw materials, pharmaceuticals
- High-performance magnetic materials based on rare earth metals such as neodymium-iron-boron and samarium-cobalt. Mineral raw materials such as kaolin, graphite, mica, talc
- Selectively ground composite materials such as metal alloys