Screw feeders are devices suitable for handling a wide variety of materials that have good flowability characteristics. The screw feeder has a helicoidal surface fitted on a shaft that rotates inside a fixed tube. The material which comes out of the silo is pushed by the helicoid flight along the base of the tube in the direction of transport. The advantages of the screw feeder include the possibility of having different openings, each with its own shut-off organ for unloading the material