In an air-swept mill, the body of which does not differ significantly in general design from a trunnion overflow mill, a powerful stream of air is passed through the mill and removes the finer particles produced by the grinding process.
A dry process air-swept ball mill. Typical roller mill layout. ... and the larger chunks produce much of the grinding action. The mill is air-swept, and the fines are carried away in the gas stream. Crushing and drying are efficient, but the product is coarse (around 100 µm), and is usually re-ground in a separate ball mill.