Advantages of fluidized bed jet mill

Since the advent of jet milling and grading equipment in the 1930s, the types have been continuously updated and the structure has been continuously improved. Bed (on-spray) jet mill, etc.

The fluidized bed jet mill is a new model that was put into use in the late 1970s and early 1980s. It has the characteristics of low energy consumption, light wear, low pollution, low noise, fine particle size and uniform distribution, etc. It is used in synthetic resin, phenolic Production of resins, PVC, pigments and dyes, powder coatings, couplers, pharmaceuticals, cosmetics, advanced ceramics, magnetic powders, abrasives, metal powders, food, spices, stearic acid, fats, waxes, mineral powders, pesticides and wettable powders been widely used in.

The fluidized bed jet mill superimposes the unidirectional jet flow and the reverse counter jet flow, and the unidirectional jet flow enters the grinding chamber through the nozzle. , a concentric reverse jet flow field is formed in the crushing area, and the crushed materials are fluidized under the action of pressure difference. Fluidization refers to the expansion of the particle bed at the critical fluidization velocity in the flow field, and the solid particles in the bed have the flow characteristics of the fluid.

The crushed materials in the crushing area are accelerated in the high-speed counter-jet flow field, and violent impact, collision, friction and shear are generated at the intersection of the jets from each nozzle, resulting in the crushing of the materials. The pulverized materials form an upward airflow around the intersection point, and the materials are brought to the upper horizontal turbine sorter for automatic classification. The powder particles that meet the requirements are selected by the sorter and then collected by the cyclone. Coarse particles slide back to the grinding chamber along the wall and continue grinding until they are separated. Therefore, the powder with good dispersibility and narrow particle size distribution can be obtained through the pulverization and classification treatment of the fluidized bed jet mill.

(1) Change the line and surface impact crushing of the traditional jet mill to the three-dimensional impact crushing of the space, and make full use of the high-speed airflow generated by the jet impact in the flow of materials in the crushing chamber, so that the crushing area is similar to a fluidized state Excellent gas-solid crushing and graded circulation flow effect, which improves the efficiency of impact crushing and the comprehensive utilization of energy. Compared with other traditional methods, the energy consumption is reduced by 30-40% on average;

(2) Since the impact crushing area and the gas-solid flow belt are placed in the middle space of the crushing chamber, the impact and abrasion of the materials driven by the high-speed airflow on the wall of the crushing chamber are avoided, and the most serious wear problem in jet impact crushing is improved, and greatly reduced. the potential for the material to be contaminated;

(3) Protective gases such as high-purity nitrogen or argon are used as the working medium to prevent oxidation, and the closed-loop operation has low gas consumption and reduces costs;

(4) There is no dust flying during the complete closed-loop operation, no pollution to the environment, and no harm to the human body;

(5) After jet milling, the activity of the powder increases. The energy of the high-speed jet flow in the jet mill crushing and classification process can not only cause the particles to be impacted and crushed, but also change the internal structure of the particles, especially the surface state, to a certain extent. The energy of the gas flow removes atoms or ions from the particle lattice, causing a mechanical loss of the crystalline structure. In this way, while the powder material is ultrafinely pulverized, the surface energy or internal energy of the particles increases, and the activity of the particles increases. The increase in the activity of the particles is not only beneficial to the chemical reaction, but also beneficial to the adsorption and coating of the particles.

(6) The particle size of the product is fine, the output is large, and it is suitable for large-scale production; the particle size classification accuracy is high, so the particle size distribution of the product is narrow, and the particle size of the product is also easy to adjust.