J+A Screw Classifier systems are free-standing units that are used for the separation of mineral grit from other types of solids.

They provide dewatering of grit from grit collection systems, separation of organics from collected grit and reduction of the pumped water volume to the classifier through the use of grit cyclones.

The screw classifier hopper maintains a water level through a series of weirs. A peripheral weir removes floating solids and a second weir, positioned within the trough wall, removes other solids that are lighter than grit. A hydro-cyclone can be used to receive the flow, and reduce the liquid delivered to the classifier, retaining the mineral particles.

Classification is an operation in which solid grains of varying  sizes and often different specific gravities are allowed to settle through a fluid under conditions that ensure a separation will be made between slower and faster settling particles.

The main purpose of a classifier is to carry out such separation, so as to effect a definite change in the size composition of the granular material. At the same time, the classifier accomplishes the equally important function of dewatering the grit and elevating the grit for discharge. In every classifier operation, there will be a feed, a rotating screw, an underflow and an overflow.