Coarse Material Screw Washer shafts utilize a combination of paddles and spiral screw flights to provide scrubbing, scouring and agitation. They are built primarily to wash crushed rock and gravel and crushed concrete generally ranging from 10mm to 65mm. They effectively remove light, loamy-type clays; dirt; crusher dust; and coatings that cannot be removed by wet screening alone. They also can be used to remove floating vegetation and soft aggregate, although all vegetation and waterlogged sticks may not be removed completely. Coarse Material Screw Washers are not intended to remove the tough plastic clay contaminants from a hard ore and rock feed that may require a Log Washer