Coarse Material Screw Washers are meant for producers looking to remove light, loamy clays; dirt; crusher dust; and other coatings that cannot be removed by wet screening alone. They are used to process crushed stone and gravel, generally ranging from 3/8- to 4-in. (10 to 100mm).
Coarse Material Screw Washer paddles are used in conjunction with screw flights to provide scrubbing, scouring and agitation. The turbulent washing action combined with the rising current water introduced at the bottom of the box from the feed end results in separation of the lighter fraction from the sound aggregate.
Lighter fractions, such as clay and floating vegetation, float to the surface due to the water rising in the box and then overflow the weir located in the back of the box. The resulting clean product is scrubbed and then conveyed by the paddles and flights to the discharge end of the box.
McLanahan Coarse Material Screw Washers feature abrasion-resistant, white iron paddles that provide maximum wear life and are reversible. This gives producers tremendous flexibility, as reversing some of the paddles will keep material in the box longer, improving retention time. If the operator chooses to move the unit or feed in larger amounts of deleterious material, it is still usable despite changing conditions.
Design elements help keep operation and maintenance simple on Coarse Material Screw Washers. A 360-degree section of flights and wear shoes located in the feed end is able to move material forward, preventing build-up in that area. Screw shafts are made of extra-heavy steel pipe shaft with inner and outer renewable and reversible abrasion-resistant hard iron paddles. Those paddles are preceded and followed by heavy-duty steel flights, equipped with bolt-on inner and outer renewable, abrasion-resistant hard iron paddles. Optional top covers are available, and drive guarding comes standard for personnel safety.
McLanahan offers lab testing for potential Coarse Material Screw Washer users at its Application Research Laboratory.