The heavy gauge Jones+Attwood screw classifier is a free-standing packaged classifier for separation of mineral grit from other solids and water discharged by grit removal systems. It can be sited adjacent to the point of collection to ease disposal. The Jones+Attwood screw classifier is designed to receive a mixture of grit and water. Pumps may be of the centrifugal, positive displacement or air lift type. The Jones+Attwood screw classifier can be manufactured in painted mild steel or stainless steel construction.
The Jones+Attwood screw classifier can be supplied with auto-lubrication for automatic operation. This also has the added advantage of reducing the frequency of maintenance visits.
A receiving header box on top of the Jones+Attwood screw classifier ensures the correct pattern of water/solids feed. This water/solids mixture enters the settlement bowl of the Jones+Attwood screw classifier where water level is maintained by a series of weirs. A peripheral weir removes any floating solids, and a second weir positioned within the trough wall scalps off any other solids that are lighter than grit.
Alternatively a hydro-cyclone can be used as a receiver for pumped flow to reduce the proportion of liquid delivered to the Jones+Attwood screw classifier, while retaining mineral particles of the specified size range. A hydro-cyclone enhances the classification of grit particles from lighter organic solids.
An inclined Archimedean screw is set within the settlement bowl, and as the screw is rotated, settled solids are transported to a point above water level. The grit product is dewatered as it is elevated and all extraneous solids and water are drained to the main sewage flow.