Medical ultrafine grinding equipment – jet mill
The micronization of raw materials can significantly improve the solubility of poorly soluble drugs, and the dissolution rate of solid preparations prepared from ultrafine powdered poorly soluble drugs can meet the requirements of domestic consistency evaluation. The jet mill is one of the most important components in the ultrafine pulverization equipment, which can pulverize the material to a few micron powder. Jet mill, also known as jet mill or flow energy mill, uses high-speed airflow or superheated steam to collide, grind and shear materials to crush them.
The working principle of jet mill in the process of powder preparation
After compressed air or inert gas is pressurized in the nozzle, the injection force of high-speed elastic fluid is used to make strong impact, shear, collision and friction between particles, gas and particles, particles and wall and other components. And so on. At the same time, under the action of the centrifugal force of the airflow rotation, or combined with a classifier, the coarse and fine particles are classified to achieve ultrafine pulverization.
(1) Flat jet mill
The flat jet mill is also called the disc jet mill. The working principle of this type of equipment is that the compressed air enters the air distribution chamber through the inlet, which will generate negative pressure, and the material enters the mixing chamber, and then is sprayed into the crushing chamber by the high-speed airflow ejected from the nozzle. room. The radial direction of the nozzle and the crushing chamber has a certain angle, so the material rotates at a very high speed under the high-speed airflow ejected from the nozzle, and performs circular motion. The materials collide with each other, and the inner wall of the crushing chamber collides, grinds, etc., so the materials are crushed. Coarse materials that do not meet the requirements are thrown to the wall to continue crushing under the action of centrifugal force, and fine powder enters the collection system of the jet mill from the outlet pipe of the crusher to collect the crushed products.
(2) Fluidized bed (counter-spray) jet mill
Fluidized bed (opposite jet) jet mill is a newer jet mill. The working principle of the fluidized bed counter-jet jet mill is that the air flow passes through a group of nozzles (number > 2) to form a counter-jet flow field in the mill, and the material is fluidized. The materials in the jet mill will have strong collision, friction and impact between the particles at the intersection point of the nozzle jet, and then be crushed. The pulverized powder passes through the classifier under the action of negative pressure, and the products that meet the requirements are collected by the cyclone separator and dust collector, while the coarser particles that do not meet the requirements are returned to the crushing area for pulverization under the influence of gravity.
The characteristics of jet mill for medicine grinding
1. The particle size distribution range is narrow, and the average particle size is fine
Through the high-pressure airflow pulverization process and the centrifugal force of the airflow rotation of the precision classifier, automatic classification of different particle sizes is realized. The particle size distribution of the obtained products is narrow, the average particle size is fine, and the D50 particle size is between 5 and 10 μm.
2. Powder shape is good, product purity is high
The appearance of the powder produced by the jet mill is spherical, the surface of the particles is smooth, the shape is regular, the dispersion is good, the mechanical wear is small during the crushing process, and the product purity is high.
3.Suitable for low melting point and thermosensitive drugs
The jet pulverizer is powered by compressed air, and the high-speed jet pneumatically produces the Joule Thomson effect. The pneumatically adiabatic collision at the nozzle reduces the temperature of the crushing system and offsets the heat generated by drug collision and friction.
4. Good sealing, no pollution
Due to the good sealing performance of the jet mill, the product yield is high; the whole crushing process is carried out under negative pressure, without leakage, no pollution to the environment, and can be operated aseptically.
5. Crushing-mixing-drying online operation
The jet mill can realize online operations such as crushing, mixing, and drying, and can also simultaneously modify drug powder. For example, some drugs are sprayed into a liquid during pulverization, covering and modifying the particles.
The jet mill has become the first choice for the development of various high-performance micro-powder materials.