The jet mill will be affected by four factors to crush the effect

With the rapid development of my country's traditional Chinese medicine industry, the machinery and equipment industry related to the deep processing of Chinese medicinal materials industry is also ushering in more development opportunities. Among them, in the pharmaceutical production process, the particle size is crucial to the bioavailability of the drug, so pulverization is a very critical link. Due to the low crushing temperature, short production cycle, high powder collection rate, uniform and fine particle size distribution, the jet mill has become a right-hand man in the pharmaceutical crushing process.

It is understood that jet mill, also known as jet mill, jet mill or energy flow mill, is a kind of superfine pulverization of solid materials by using the energy of high-speed airflow (300-500m/s) or superheated steam (300-400℃). mechanical equipment. As one of the commonly used ultra-fine crushing equipment, the jet mill is widely used in the ultra-fine crushing and dispersing of superhard materials such as chemical materials, medicine and food, and metal powder.

Some customers said that the micro-nano jet mill has a wide range of crushing particle sizes and is easy to operate, but in the crushing process, the crushing effect often appears different. What's going on here? A technician from a powder equipment company said that the pulverization effect of the jet mill is mainly affected by the following factors: gas-solid ratio, feed particle size, temperature and pressure of working fluid, and pulverization aids.

Gas-solid Ratio
It is understood that the gas-solid ratio of the jet mill during pulverization is an important technical parameter and an important index. If the gas-solid ratio is too small, the kinetic energy of the airflow will be insufficient, which will affect the fineness of the product. But if the gas-solid ratio is too high, it will not only waste energy, but even deteriorate the dispersion performance of some pigments.
Therefore, the technicians suggest that when the user uses superheated steam as the working medium, the gas-solid ratio of the calcined hard material is generally controlled at 2-4:1, and the crushed surface-treated material is generally controlled at 1-2 :1.

Feed Size
When crushing hard materials, there are also strict requirements for the particle size of the feed. As far as titanium powder is concerned, the crushing calcined material needs to be controlled at 100-200 mesh; the crushed surface-treated material is generally 40-70 mesh, and should not exceed 2-5 mesh.

Working Fuid Temperature
Technicians said that when the temperature of the working fluid is too high, the flow rate of the gas will be accelerated. Taking air as an example, the critical velocity at room temperature is 320m/s. When the temperature rises to 480°C, the critical velocity can be increased to 500m/s, that is, the kinetic energy increases by 150%. Therefore, increasing the temperature of the working medium is beneficial to improve the crushing efficiency Effect.
In addition, when pulverizing titanium powder, the temperature of superheated steam is generally about 300-400°C. Technicians said that the temperature is generally high during crushing and calcination, and the temperature is relatively low when crushing surface-treated materials. "Some surface treatment agents, especially organic surface treatment agents, are not resistant to high temperatures, so they only need to be overheated on the basis of the original steam temperature. 100°C is enough."

Working Fluid Pressure
It is understood that the pressure of the working fluid is the main parameter to generate the jet flow velocity, and it is also the main parameter that affects the crushing fineness.
Generally speaking, the higher the working fluid pressure, the faster the speed and the greater the kinetic energy. So, how high the pressure should be chosen when crushing? Technicians said that it mainly depends on the crushability and fineness requirements of the material. For example, when superheated steam is used to pulverize titanium powder, the steam pressure is generally 0.8-1.7MPa, while the generally pulverized calcined material is higher, and the pulverized surface-treated material can be lower.

Crushing Aid
Technicians said that during the pulverization process of the jet mill, if an appropriate pulverization aid is added, not only the efficiency of the pulverization can be improved, but also the dispersion performance of the product in the medium can be improved. So how to choose crushing aids?
It is understood that during the surface treatment of titanium dioxide, most of the added organic surfactants have the function of grinding aids, while the inorganic grinding aids generally use sodium hexametaphosphate and sodium (potassium) pyrophosphate.

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