The fluidized bed jet mill consists of an air compressor, an air purifier system, a supersonic jet mill, a classifier, a cyclone, a dust collector, and an exhaust fan. Medium and small fluidized bed type airflow superfine pulverizer, usually combining supersonic airflow pulverizer, classifier, cyclone separator, dust collector and exhaust fan into an integrated machine, which can greatly save floor space and facilitate installation, Transportation and use. The fluidized bed jet mill is a device that uses high-speed airflow to achieve ultrafine crushing of dry materials. The compressed gas is sprayed through the nozzle at high speed in the pulverizing area to drive the powder material to move at high speed, and impact at high speed at the intersection of the four nozzles to achieve self-crushing. The pulverized material rises to the grading area with the negative pressure, and the particles are rotated by the grading wheel at high speed. The centrifugal force and the simultaneous action of the negative pressure of the fan on the centripetal force, the larger the particle size, the greater the centrifugal force, and the small particles that reach the required particle are collected into the cyclone and the trap through the gap of the stepped wheel blade. The large particles that are pulled out by the centrifugal force are returned to the crushing zone to continue to be pulverized.
In the ultrafine pulverization process, in order to obtain a powder of several micrometers or even finer, it is not feasible to use an ordinary screening method. Therefore, the machine is provided with a turbo classification system in the classification room, which is a typical structure using a centrifugal force field. The pulverized material in the pulverizing chamber is pushed by the ascending airflow. Under the action of the horizontal turbine horizontal classifier, if there is the same particle at the edge of the rotating section of the turbine, the granule will be subjected to two different forces of the centrifugal force field. That is, the centrifugal inertial force F and the airflow resistance R generated by the rotation of the turbine. The particle size of the particles is assumed to be d, the density is δ, the density of the medium 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 equations, respectively: R = 3πηd Ur.
When the particles are larger, the centrifugal force is greater than the resistance, that is, when F>R, the large particles fly toward the wall of the classification chamber along the tangential direction of the turbine, and then return to the crushing chamber to be pulverized again. When the centrifugal force is less than the resistance, ie F
Fluidized bed jet mill advantages:
(1) Low energy consumption. Compared to a disc airflow mill, the average energy consumption is reduced by 30-40%. Mainly due to the following reasons: (A): jet kinetic energy is used by Zuijia; (B): large combined force of multi-directional simultaneous collision airflow; (C): closely matched with super-segmentation machine to make qualified fine-grain products timely Exhaust, only the unqualified coarse particles are returned to the pulverizing chamber for secondary pulverization, so that excessive pulverization of the particles can be prevented, thereby reducing energy loss.
(2) The wear and the adhesion are small, the medium passing through the nozzle only has air and does not enter the crushing chamber in the same way as the material, thereby avoiding the impact, friction and sticky deposition of the particles on the way, and also avoiding the particles to the pipe and the nozzle. Wear and tear.
(3) The particle size of the product can be adjusted by the classifier. Therefore, the particle size distribution is relatively narrow, and the adjustment of the classifier is completely independent.
(4) It adopts high-performance motor, stable operation and high speed; optimized design of grading wheel and made of aviation material, featuring high linear speed, high cutting precision and narrow particle size distribution;
(5) Innovative top feeding mode, uniform control of feeding, pre-screening of fine powder in raw materials, avoiding excessive pulverization of raw material fine powder and improving pulverization efficiency;
(6) According to the requirements of the laboratory requiring less balance of raw materials, the bottom nozzle structure is designed, which can basically complete the pulverization of the material in the crushing cavity, and the residual is few, which solves the defect that many residual materials in the conventional laboratory crushing equipment can not be crushed.
Disadvantages of fluidized bed jet mill: The material can only be broken after being fluidized in the fluidized bed collision jet mill. Therefore, it is required that the pulverized raw material has sufficient fineness, and the demand for a material having a high density is more prominent. If the particle size and density are large, the fluidized state cannot be formed in the pulverization chamber, and the pulverization cannot be performed. This is a major limitation. The classifier blades are in contact with solid particles for a long time at high speed, and the wear is quite serious.
