Hicom recommend a high efficiency classifier design which enables efficient cuts at ultrafine sizes, maximises productive performance and minimises system specific energies.

For an optimum system, it is essential that the maximum amount of product is recovered from the grinding mill discharge at the required size, and that fine particles that adhere to the coarse particle returns are effectively washed clear from this stream.

The feed material enters the classifier suspended in air through a horizontal pipe tangentially positioned just above the rotor. This ensures maximum exposure of all particles in the feed stream to the primary separation zone of the classifier where initial classification of fine particles takes place

The rotor accelerates the material to its peripheral speed, thus creating a centifugal force on the particles acting against the drag forces acting on the particles due to the air flowing through the rotor. The finest cut size achieved is thus determined by a balance between centrifugal and drag forces at the rotor.

Coarser particles in the feed stream are forced through a narrow opening between the rotor and static blades where they are exposed to a primary secondary air flow (A). This air stream creates additional shear forces which ensure that only coarse particles proceed down to the lower coarse fraction outlet, while particles slightly finer than the cut size report to the finer material fraction.

An additional secondary air stream (B) is introduced tangentially below the rotor. This air stream is used to wash free fine particles agglomerated on the surface of coarser grains. It also reduces settling velocity of the particles in both classificatrion zones, which is critical to obtaining optimal classification efficiency.