The difference between open-circuit jet mill and closed-circuit jet mill
Jet mill is a kind of micron level ultra-fine grinding equipment, which is more common in various powder industries. The jet mill has two different structures, divided into open-circuit and closed-circuit. The open circuit system usually refers to the use of air as a medium to crush, filter and discharge after crushing. The closed-circuit system refers to the use of inert gas as the medium. The materials in the system are under the protection of inert gas during the entire process of feeding, crushing, grading, conveying, separating and packaging. After dust removal and filtration, the inert gas is returned to the front-end system for recycling.
1. Open-circuit jet mill
Jet mill (fluidized bed jet mill) is the compressed air accelerated by Laval nozzle into supersonic air flow and then injected into the crushing zone to make the material fluidized (air flow expands into fluidized bed suspension boiling and collides with each other), so Each particle has the same state of motion. In the crushing zone, the accelerated particles collide and crush at the intersection of the nozzles. The crushed materials are transported to the grading area by the ascending airflow, and the fine powder that meets the particle size requirements is screened out by the grading wheel, and the coarse powder that does not meet the particle size requirements is returned to the crushing area to continue pulverization. The qualified fine powder enters the high-efficiency cyclone separator along with the air flow and is collected, and the dust-containing gas is filtered and purified by the dust collector and then discharged.
2. Closed-circuit jet mill
The closed-circuit jet mill generally refers to the air jet mill based on the air outlet of the pulse dust collector connected with the air inlet of the air compressor that provides the power source of the system to form a closed system to make the smashing medium of the entire pulverization process ( Air or inert gases such as nitrogen, argon, helium, carbon dioxide, etc.) circulate in a closed system.
The closed-circuit jet mill is a closed-circuit jet pulverization system developed for the crushing requirements of special materials such as flammable, explosive, easy to oxidize, and volatile. It is protected by inert gas circulation. The working process is that the cooled inert gas is accelerated by the Laval nozzle into a supersonic airflow and sprayed into the central crushing area of the pulverizer. The sonic airflow brings the animal material to collide with each other in the crushing area to achieve the goal of crushing. The crushed material enters the classification area with the updraft, and the powder material that meets the particle size requirements is sorted by the classification wheel in the classification area. The particle size of the powder is sorted by adjusting the speed of the grading wheel. The sorted products are discharged from the centrifugal separator along with the airflow or collected after being filtered by the dust collector. The unqualified ones continue to return to the crushing area for two Smashed. The filtered inert gas is compressed and recycled by the compressor system, and the whole process is automated.
The open-circuit jet mill can be used for the processing of most common powder materials, and the closed-circuit jet mill is mainly used for flammable, explosive, and oxidizable raw materials. The user can choose according to the raw materials and processing requirements.