The large fluidized bed ultrafine jet mill is composed of an air compressor, an air purifier system, a supersonic jet mill, a classifier, a cyclone separator, a dust collector, an exhaust fan, etc., and a medium and small fluidized bed ultrafine jet mill The machine is usually composed of a supersonic jet mill, classifier, and classifier. The cyclone separator, dust collector, and exhaust fan are combined into one, which can greatly save the area and facilitate installation, transportation and use.

1 crushing principle

The fluidized bed ultrafine jet mill is composed of a silo, a screw feeder, a feeding chamber, a crushing chamber, a cyclone separator and a dust collector.

First, the materials to be crushed are transported from the silo to the feeding chamber through the screw feeder, and the materials fall into the crushing chamber under the action of gravity.

There are specially designed high-pressure air inlet nozzles around the crushing chamber, and the nozzles are in the opposite direction. The purified and dry compressed air is ejected from the nozzle to form an ultrasonic air flow. The material collides at the center of the intersection of the high-speed airflow and is instantly crushed.

The pulverized particles rise to the classification chamber with the air flow, and the qualified particles enter the cyclone separator with the air flow to finally obtain the desired product, and the tail gas is discharged into the dust collector.

Under the action of the classifier, the larger particles fall into the crushing chamber again and are crushed again until a qualified product is obtained.

2 Principles of Airflow Classification

In order to obtain fine powders of a few microns or more in the ultrafine grinding process, it is not feasible to use ordinary sieving methods. Therefore, the machine is equipped with a turbine-type classification system in the classification chamber, which is a typical structure using centrifugal force field.

Under the action of the horizontal turbine classifier in the classification chamber, if there are the same particles at the edge of the turbine rotating section, the particles will be affected by the forces of two different centrifugal force fields. They are the centrifugal inertial force F and airflow resistance R generated by the rotation of the turbine.

Suppose the particle size is D, the density is δ, the medium density is ρ, the tangential velocity of the particles is UT, the average radius of the turbine is r, the viscosity of the medium is η, and the radial velocity of the particles is ur. These two forces can be expressed by the following formula:

R=3 feet

When the particles are large, the centrifugal force is greater than the resistance, that is, when f>R, the large particles fly to the wall of the classifier along the tangential direction of the turbine, and then return to the crushing chamber to be crushed again.