Air Classifiers are normally used when the particle size that needs to separate is too fine for a screen. The air classified product can be the Coarse without Fines/Dust or the Fines without Coarse/Grit.

In order to effectively remove the fine powders, the surface moisture must be very low, less than 1 – 2% is best but some fines can be removed even at 2.5-3%.

Yes. Air Classifiers do not operate at the high speeds that pulverizers do and with adequate wear protection can economically be used to process even abrasive ceramic powders.

Air Classifiers can separate powders as coarse as 80 mesh or as fine as 2-3 microns.

Yes. Density plays a role in Air Classifier separation, but the internal air currents are really affecting the overall mass/weight of the particles in the feed. Lighter/Smaller particles are removed by the airflow, while Heavier/Lighter particles are not entrained in the airflow. It must be noted that an air current will view the mass/weight of a Large/Low density particle as being similar to the mass/weight of a Small/High Density particle.

The fineness of Air Classified products is controlled by the quantity of rejector blades, the speed of the rejector blades, the velocity of the airflow and the feed rate.

Air classifiers are categorized as Internal Fan models and External Fan Models. Internal Fan models re-cycle the air and do not require cyclones or baghouses to collect the separated fines. External Fan Models require cyclones or baghouses to collect the separated fines.

In most cases Air Classifiers do not fracture the powders because Air Classifiers do not operate at high speeds as do the pulverisers. However, in cases where the feed powder consists of very soft agglomerates, some fracture can occur.

Yes, in fact, Air Classifiers commonly operate in closed-circuit with a mill. This maximizes the capacity of the mill and reduces the mill’s energy cost because it does not have to be the sizing device.

Yes. Air Classifiers can be fed pneumatically and, in many cases, offers the opportunity to install the unit in a pneumatic conveying line. However, it should be noted that the particles in a pneumatic fed process enter the Air Classifier at much higher velocity than gravity fed particles. Particles that approach the rejector blades at higher velocities are more likely to pass through, which requires a higher rejector speed to stop the oversize particles. Generally, this results in higher wear and lower fines removal efficiency.