High Consistency Cleaner which takes place after the pulper, is specially designed to remove high and medium specific gravity contaminants from stock slurries with consistencies that usually range between 2.5 and 5.5%.

Waste paper from the pulper is pumped under pressure into the inlet chamber, and the tangential entry design of the cleaner inlet allows it to convert the kinetic energy of the pulp slurry into a rotating mass within the cleaner. As the slurry rotates inside the cleaner, shear planes are caused by acceleration of the pulp slurry as it travles from the outside diameter of the cleaner radially inward the axis of rotation, where it is then diverted upward through the vortex finder out of the top of the cleaner. These shear planes tend to strip high-density particles from the pulp fiber.

In addition to the shear planes, the rotational motion results in extremely high centrifugal forces that push high-specific-gravity particles to the outside of the cleaner wall where they migrate down into the heavy reject collection chamber. Rejects are then discharged intermittently by an automatic discharge system. Contaminants such as rocks, nuts, bolts, nails, paper clips, junk metal and other heavy debris are trapped by the cleaner and retained in a rejects chamber.  The chamber is then dumped through a valve, which is controlled by a sequence timer, into a dumpster or sediment sepatator. Using a high-density cleaner to remove contaminants that have passed through the pulper extraction plates or screening drums, also can protects the following equipment from damaging.