Ultra-fine grinding equipment – “Jet Mill”
Jet milling technology is a superfine pulverization technology that has developed rapidly in recent years. Because of its advantages such as high crushing strength, fine particle size, narrow distribution, low product pollution, and the use of inert gas, it is widely used in medicine, chemical raw materials and It has been widely used in the preparation of special powders.
The jet mill is to accelerate the compressed air or inert gas through the nozzle, and use the energy of high-speed elastic fluid (300~500m/s) or superheated steam (300~400℃) to make particles, gas and particles, There are strong impacts, shearing, collisions, frictions, etc. between the particles and the wall and other components. At the same time, under the action of the centrifugal force of the airflow rotation or combined with the classifier, the coarse and fine particles are classified to achieve ultra-fine crushing. equipment. As a common preparation method for pharmaceutical powders, jet mill is suitable for crushing antibiotics, enzymes, low-melting point and other heat-sensitive drugs.
The types of jet pulverizers used for pharmaceutical powder preparation mainly include: disc jet pulverizer, circulating tube jet pulverizer, target jet pulverizer, ring jet pulverizer, collision jet pulverizer, fluidized jet pulverizer Bed collision air pulverizer.
Because the jet mill uses gas as kinetic energy to achieve crushing, its crushing mechanism is different from other mechanical equipment. Specifically in:
01 Narrow particle size distribution range, fine average particle size
During the pulverization process, due to the centrifugal force of the high-precision classifier airflow, the coarse and fine particles are automatically classified, so the obtained product has a narrow particle size distribution range and a fine average particle size. The D50 is generally between 5 and 10 μm.
02 Good powder shape, high product purity
The powder produced by the jet mill tends to be “spherical”, the particle surface is smooth, the shape is regular, the dispersibility is good, and the mechanical wear is small during the pulverization process, and the obtained product is of high purity.
03 Suitable for low melting point, heat sensitive drugs
The jet mill is driven by compressed air. The high-speed jet airflow produces the Joule-Thomson effect. The airflow collides adiabatically at the nozzle, thereby reducing the temperature of the pulverization system and offsetting the heat generated by drug collision and friction. The ambient temperature in the pulverization chamber can reach It is tens of degrees Celsius below zero, so it is suitable for preparing low melting point and heat-sensitive drugs.
04 Good airtightness, no pollution
Due to the good airtightness of the jet mill, the product yield is high; the whole crushing process is carried out under negative pressure, and the crushing will not leak, so it has no pollution to the environment and can be operated in a sterile state.
05 Easy to operate
The crushing process is continuous, using closed circulation system technology and automatic control technology, and is easy to operate.
06 Crushing-mixing-drying online operation
Jet pulverizer can realize pulverization, mixing and drying on-line operation, and can also simultaneously modify drug powder, for example, some drugs are sprayed into liquid while pulverizing, for particle coating and surface modification.
In the pharmaceutical process, ultrafine powder drugs are generally obtained through micron powder crystallization and ultrafine crushing. In view of the characteristics of ultrafine drugs such as miniaturized particle size and high quality purification, the main machines suitable for ultrafine crushing of drugs include: mechanical impact crusher, ball mill, vibration mill, stirring mill, bidirectional rotating ball mill, airflow pulverizer, etc.