What factors depend on the particle size of the ultra-fine jet mill

There are two basic methods for obtaining ultra-fine powders, one is physical method, the other is chemical synthesis, and the other is a hybrid method based on these two methods. And nanomaterials are generally prepared by a hybrid method. The main equipment for preparing ultra-fine powder by physical method is grinder, classifier and collection equipment of various principles. The ultra-fine jet mill is an important way to obtain ultra-fine powder by dry processing.

The ultra-fine jet mill is the shearing of the material by the high-pressure airflow, the impact between the particles of the material itself, the impact and friction between the material and other parts of the equipment, and the material is smashed. The ultra-fine jet mill can be operated in an aseptic state. The average particle size of the material after airflow pulverization is fine, the particle size distribution is narrow, the particle shape is regular, the surface is smooth, and it has the characteristics of high purity, high activity, and good dispersibility. Moreover, it does not generate heat during pulverization, and is suitable for pulverizing low-melting and heat-sensitive substances. Therefore, the ultra-fine jet mill is very suitable for the ultra-fine preparation of drugs. According to statistics, about 25% of ultrafine jet mills in the world are used in the pharmaceutical industry.

The control of the particle size of the product by the ultra-fine jet mill mainly depends on the size of the raw material, the crushing pressure, the feeding pressure, and the feeding speed. The specific logical relationship between the ultra-fine jet mill and these parameters is: the smaller the particle size of the raw material, the higher the crushing efficiency; on the contrary, the larger the particle size of the raw material, the relatively low crushing effect. When the crushing pressure and the feed pressure are constant, the product will be finer when the feed rate is reduced, and the product will become coarser when the feed rate is increased. In the case of a certain feed rate, the particle size of the product will be finer when the crushing pressure is increased, and the product will become coarser when the crushing pressure is reduced. Therefore, particle size control is achieved by adjusting the parameters of the ultra-fine jet mill during the crushing process to achieve different crushing fineness. Before crushing, it is necessary to determine the relationship between the feed rate and the pressure and then determine the appropriate crushing parameters to achieve the customer’s Granularity requirements. The particle size of the product needs to use a particle size detector to check the fineness and distribution range. In addition, if the electron microscope is used for measurement, it can be more accurate. Of course, you can also compare the detection results with the internationally famous particle size detector.

The ultra-fine jet mill is a relatively precise machine. In the daily use and maintenance process, some details still need to be paid attention to by the operator. In order to improve the crushing efficiency of the ultra-fine jet mill, it is necessary to check whether the raw materials meet the requirements before production. It is strictly forbidden to mix foreign objects in the raw materials. During production, a certain amount of materials must be kept in the grinding cavity of the ultra-fine jet mill. Under the condition of constant pulverizing gas flow, there are more materials in the grinding cavity, and the classifier current is large; there are few materials in the grinding cavity, and the classifier current is small. In addition, the feeding speed must be uniform and stable, not too fast or too slow. If the feeding speed is too fast, the equipment will be overloaded.

The equipment should be maintained regularly, and the air supply pressure should be checked frequently to see if it has reached the pressure required for crushing, as well as the grading motor of the ultra-fine jet mill. After 3000 hours of operation of the equipment, or long-term shutdown and long-term storage before reusing it, please promptly Clean up the materials adhering to the nozzle of the ultra-fine jet mill, the inner wall of the mill cavity and the grading part to prevent the impact of the ultra-fine jet mill’s smashing effect.