Some applications require extremely fine particles or solids content that are particularly difficult to break down and disperse. These requirements require something more than a dissolving disc, and this is where using a bead or basket mill comes in. High speed bead mills are very useful in dispersing otherwise difficult materials. All the steps of the standard disperser still apply (wetting, mechanical failure, stabilization), but the bead mill consists of a milling room and agitator. The milling chamber contains beads made of glass, steel or zirconia, the disc holder, and the milling slot has grinding media kept in motion by a motor-driven stirrer. The actual dispersion takes place between the grinding beads, the rotor and the sides of the vessel.
Basket mills use a rotating perforated basket with discs containing spikes that allow for grinding. While the basket moves, the discs remain stationary and use centrifugal force to accelerate the grind. The sieving basket is also filled with grinding beads, so there is a shearing force between the beads, rotating basket and stationary disc that provides dispersion.
