SCREW CONVEYOR

PROBLEM TO BE SOLVED: To make moisture returnable in the middle of conveyance in a screw conveyor for transferring sand and dregs collected in a sewage sand basin and sludge or the like collected in a sand basin. SOLUTION: A region 18 for urging the backflow of moisture in a conveyed material in conveyance is formed at a part in the axial direction of a screw 2. A base end 9 in the conveying direction of the region 18 is provided with a drain port 10 for draining moisture raised in the level by the backflow, to the outside from a sidewall of a casing 1. As a means for forming the region 18, a cutout 5 is provided on a spiral blade 4, and a predetermined range from the front side to the rear side of a position provided with the cutout is constituted as a double threaded screw part 16 by providing an auxiliary spiral blade 6. The auxiliary spiral blade 6 is set to a length enough to receive the conveyed material flowing backward through the cutout 5 and to feed the conveyed material onto the spiral blade in front of the cutout 5, and made better in moisture flow-through property than the spiral blade 4. COPYRIGHT: (C)2006,JPO&NCIPI