Jet mills (or jet pulverizers) are equipment that utilizes high-speed airflow to achieve ultrafine grinding of materials. The core principle involves accelerating particles through airflow, causing collisions between particles, friction, and impact with internal components to achieve comminution. The particle size of powders processed by air jet milling can be adjusted through the following key operational parameters.
1. Adjusting Classifier Wheel Speed
The classifier wheel separates coarse and fine particles via centrifugal force. Its rotational speed directly affects the separation efficiency. Enhances centrifugal force, allowing finer particles to pass through the wheel, resulting in a smaller product size. Reduces centrifugal force, permitting larger particles to pass, leading to a larger product size. Suitable for applications requiring strict control over particle size distribution, such as ultrafine powder processing.
2. Adjusting Air Volume and Velocity
Air volume and velocity determine the residence time of material in the grinding chamber and the frequency of collisions. Shortens residence time and reduces collision frequency, but increases energy per collision, generally resulting in finer particles. Extends residence time and increases collision frequency, but reduces energy per collision, potentially leading to larger particles or a broader size distribution. Balance air volume and grinding pressure to avoid coarse particles being carried out due to excessive airflow.
3. Controlling Grinding Pressure
Grinding pressure directly affects the intensity of particle collisions. Raises collision energy, enhancing grinding efficiency and reducing particle size. Lowers collision energy, resulting in larger particles. Beyond a certain threshold (e.g., 13 bar), further increases in pressure have limited effect on particle size reduction. Other parameters should be adjusted in conjunction.
4. Optimizing Feed Rate
Feed rate influences material distribution and residence time in the grinding chamber. Extends residence time and increases collision frequency, reducing particle size, but may decrease grinding efficiency due to excessive material layer thickness. Shortens residence time, increasing particle size, but must avoid equipment overload from overly rapid feeding. Monitor classifier current and chamber material level to ensure the feed rate matches grinding capacity.
5. Adjusting Nozzle Parameters
Nozzle size and shape affect air velocity and material acceleration. Increases airflow velocity and material acceleration, reducing particle size, but may require regular cleaning due to higher clogging risk. Adjust nozzle angle or quantity to improve material dispersion and reduce agglomeration.
6. Adjusting Distributor Tube Position
The position of the distributor tube affects material trajectory and residence time in the grinding chamber. Extends residence time and increases collisions, reducing particle size. Shortens residence time, increasing particle size. Suitable for scenarios requiring high uniformity in particle size distribution.
7. Adapting Parameters Based on Material Properties
Higher hardness materials require greater grinding pressure and smaller nozzle throat diameters. Control airflow temperature and humidity to prevent overheating or agglomeration. Finer raw materials improve grinding efficiency, feed rate or pressure may be reduced appropriately.
8. Operational Recommendations
Particle size control requires coordinated adjustment of classifier speed, airflow, grinding pressure, etc. Avoid excessive adjustment of a single parameter to prevent equipment issues. Use particle size analyzers or electron microscopes to regularly inspect product size and dynamically optimize parameters. Regularly clean nozzles, classifier wheels, and other components to prevent clogging or wear that could impact particle size control accuracy. These methods, based on jet mills parameter optimization and process control, can precisely meet the particle size requirements of various materials—such as stringent demands in chemicals, non-metallic minerals, and new materials industries.
Experience the Epic Powder of Precision
At Epic Powder, we specialize in advanced jet mills solutions that deliver unparalleled control over particle size distribution. Our air jet milling technology ensures consistent, high-quality results tailored to your specific needs — whether in pharmaceuticals, ceramics, or specialty chemicals. Trust Epic Powder to transform your materials into superior products with precision and reliability.