A spiral jet mill is a piece of equipment used to reduce the particle size of pharmaceutical and fine chemical powders down to few micrometers.
It is made of different components, each designed for a specific part of the micronization process. The product is first poured in a feeder where it is fed into the product line of the mill. Once it enters the milling chamber it is accelerated by means of a high pressure gas so that the particles collide against each other until they are small enough to escape it and flow through the filtration system. When the powder is separated from the gas it can be finally dispensed inside a bag or a drum either directly or by means of a metering system.
A jet mill can be used to process explosive powders as long as it is designed to do so.
All the electrical components (i.e. the feeder, the metering system or any additional accessory) must be Ex-proof certified according to the current local regulation (ATEX, NEC, …). As the powder flows inside a process gas, this must be inert so that fires and explosions are avoided. The most widely used in the industry is nitrogen but other gases can be considered according to the process.
Brand new jet mills can be specifically designed according to the hazardous classification of the power and of the installation. If an existing unit is already available, after a technical evaluation it can be easily retrofitted to be safely used to handle explosive powders.