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Reliable and robust grit separation

Jones + Attwood Screw Classifier

The Jones + Attwood Screw Classifier systems are free-standing units used for the separation of mineral grit from other types of solids.

The classifier is designed to separate pre-screened solids of varying specific gravities. At the same time, the classifier accomplishes the important function of dewatering the grit and elevating it for discharge into a dumpster. In every classifier operation, there will be a feed, a rotating screw, an underflow and an overflow.

The Screw Classifier incorporates the original Jones + Attwood features that have a proven a record of reliability and robustness. This system has been successfully installed in hundreds of installations worldwide and can fit into multiple applications to suit partner needs where small sediment particles must be separated to protect downstream equipment. The Screw Classifier has the following features and benefits:

  • Jones + Attwood Grit Classifier works in conjunction with a range of industry standard hydro-cyclone to reduce the volume of pumped water to the classifier
  •  The hydro-cyclone is designed to remove at least 95 percent of the grit entering the feed inlet that is larger than 150 mesh with a specific gravity of 2.65 s.g. or greater. Higher capture efficiencies are available on request
  • High-quality stainless-steel construction
  • Robust screw operating in a grit bed or UHMW liners
  • High capacity mechanical/electrical drive system with ample overload capacity

The pumped grit / water mixture enters the hydro-cyclone to receive the flow and reduce the liquid delivered to the classifier, retaining the mineral particles that drop into the settlement bowl of the screw classifier unit where the water level is maintained by a weir. Any floating solids will flow over the weir within the trough wall to scalp off those solids that are lighter than grit.  

As the grit settles within the main trough, an inclined Archimedean screw elevates and transports the grit above the water level. The grit product is dewatered as it is raised by the screw to a high discharge point and into a dumpster. All flow that passes over the weir is directed back to the main sewage flow.