Screw conveyors

Features and structure

The material to be moved is fed and discharged by one or more inlets/outlets that may be supplemented by knife gates and valves. 

The material is moved by a robust steel spiral. It is a helicoid without a central shaft or core, with greater conveyor capacity, less sensitivity to fibrous or clogging materials, and the ability to transport products in a wide range of sizes.

Screw conveyors cater for highly compact installations in a reduced space. Screw conveyors operate by “pushing” or “pulling”. A screw conveyor that operates by “pushing” can directly feed a second screw conveyor by coupling one to the other, without requiring the use of hoppers. The second screw conveyor may be mounted at a different angle and/or direction to the first one. 

As the spiral has no central shaft, it is always in contact with the trough, which is protected by a replaceable sleeve. There are different kinds of protective sleeves, which are made of ultrahigh molecular weight polyethylene (PE-1000 UHMW), Adiprene…depending on the material to be moved. In order to reduce wear, the screw should be filled with as much material as possible when in operation.

The screw may be fitted with drainage sections to facilitate the decanting of the liquids in the solid materials. The effective dehydration of the solids being transported requires the use of the compacting conveyor.

The spiral is modified or supplemented in some installations for the following reasons: 

• Increase the capacity of sloping screw conveyor.
• Increase the strength of the screw on very long screw conveyors and on compacting conveyors.