An air separator comes in handy when very fine materials are to be separated from coarse and where normal vibrating screens tend to have very low efficiency and give frequent trouble by choking etc. Fine materials of 200 mesh or more are separated from coarse when a material containing fines is passed through the separator,with a separating efficiency of more than 95%. This can be used for separation of even coarser materials upto 1 mm. The efficiency of the separator though tends to be lower as more and more coarse material is separated.

Working - Material is fed to the separator through a chute at the top which can be connected directly or indirectly to the outgoing chute of the mill. It falls through the admission cone onto a spray plate which is rotating at a high speed. This throws the materials towards the outside by centrifugal action. The various fans are also rotating at a high speed and they generate an air current the lighter material rises up,getting separated from the coarse grains. It passes through various fan blades,taking the path shown by the arrows. While moving up,further separations take place.
When the air starts flowing downwards near the outer casing the fine material drops off and comes out through the cone of the outer casing. The cone can be fitted to chutes directly over the hoppers or to conveyors to transport the fines as desired. (Suitable air sluices may be provided if desired.) The air again goes into circulation through the shutters as shown

Construction - The fabricated steel plate body of this separator has been so designed as to provide ease in erection and transport. Since material is going to remain in contact with the casings,they are suitably lined with plates to increase the life of the body. All the fans are of removable type so that they can be easily replaced when worn out. Man-hole door is provided for easy access within the separator while changing of worn out parts and other maintenance work. Suitable adjustments are provided with the fans to control the fineness of the material to be separated.

Feed - For maximum efficiency the feed to the separator should be continuous and at a constant rate. If the grinding of the feed is uniform this also helps in better separation.