What are the types of jet mills

The main applicable crushing mechanism of the jet mill determines its wide application range and high fineness of the finished product. Typical materials are superhard diamond, silicon carbide, metal powder and so on. , Ceramic pigments, medicine, biochemistry, etc. High purity, low temperature of medicine and PVC. By changing the ordinary air in the gas source into inert gases such as nitrogen and carbon dioxide, the machine can be used as an inert gas protection device, suitable for the crushing and classification of flammable, explosive, and oxidizing materials.

 

The jet mill, cyclone separator, dust collector and induced draft fan form a complete pulverizing system. After the compressed air is filtered and dried, it is sprayed into the crushing cavity at high speed through the Laval nozzle. The materials are repeatedly collided, rubbed, and sheared at the intersection of multiple high-pressure air streams. Under the action of the suction of the fan, the crushed materials move to the classification area with the updraft. Under the action of the strong centrifugal force generated by the high-speed rotating classifying turbine, the coarse and fine materials are separated. The fine particles that meet the particle size requirements are collected by the cyclone separator and dust collector through the classification wheel, and the coarse particles drop to the crushing zone and continue to be crushed.

 

There are several types of jet mills used in industry: flat jet mills, fluidized bed jet mills, circulating tube jet mills, jet mills and target jet mills. Among these types of jet mills, flat jet mills, fluidized bed jet mills and circulating tube jet mills are widely used.

 

Convection jet pulverizer

 

After the material enters the crushing chamber through the screw feeder, the impact energy of the high-speed airflow is ejected from several oppositely arranged nozzles, and the airflow rapidly expands into the fluidized bed and the collision friction force generated by the suspension and boiling breaks the material. Driven by the negative pressure airflow, the coarse and fine mixed powder passes through the turbine classification device at the top, the fine powder is forced through the classification device, and is captured by the cyclone collector and the bag filter. The coarse powder is combined by the gravity generated by the high-speed rotating classification device. The centrifugal force hits the four walls, and then settles back to the crushing chamber to continue crushing.

 

Flat jet mill

 

The high-pressure air flow as the kinetic energy of the crushing enters the stable air storage bag outside the crushing chamber as the air distribution station. The air flow is accelerated into a supersonic air flow through the Laval nozzle and then enters the crushing mill cavity. The material is accelerated and then introduced into the crushing mill cavity through the Venturi nozzle Perform synchronous crushing. Because the Laval nozzle is installed at an acute angle with the crushing chamber, the high-speed jet will circulate the animal material in the crushing chamber, and the particles will collide with each other and collide with the wall of the fixed target plate to frictionally break. The fine particles are introduced into the central outlet pipe of the pulverizer, and are collected in the cyclone separator driven by the centripetal air flow. The coarse powder is thrown toward the peripheral wall of the pulverizing chamber for circular motion and continues to be crushed.

 

Circulating tubular jet mill

 

The raw materials are fed into the crushing chamber through the venturi nozzle, and the high-pressure airflow is sprayed into the racetrack-shaped circular tube crushing chamber with variable diameters and variable curvatures through a set of nozzles, accelerating the collision, collision, friction and crushing of particles. At the same time, the cyclone also drives the crushed particles along the pipeline into the classification zone. Under the action of the centrifugal force field in the classification zone, the dense material flow is divided, and the fine particles are discharged after being classified by the inner louver inertial classifier. Coarse particles return to the outer layer along the downcomer and continue to circulate and crush.

 

Fluidized bed jet mill

 

The jet mill (fluidized bed jet mill) accelerates the compressed air through the Laval nozzle into a supersonic airflow, and then sprays it into the smashing zone to fluidize the material (the airflow expands into a fluidized bed suspension, boiling, and colliding with each other). Every particle has the same state of motion. In the crushing zone, the accelerated particles collide with each other and are broken at the intersection of the nozzles. The pulverized material is transported to the grading area by the updraft. The fine powder that meets the particle size requirements is sieved by the horizontal grading wheel, and the coarse powder that does not meet the particle size requirements is returned to the pulverizing area to continue pulverization. Qualified fine powder enters the high-efficiency cyclone separator with the air flow for collection, and the dust-containing gas is filtered and purified by the dust collector and discharged into the atmosphere.