Coarse Material Screw Washers

Coarse Material Screw Washers are used to wash crushed stone, gravel and other hard ores, generally ranging from 10 to 100mm (3/8" to 4″) that contain light, loamy clays; dirt; crusher dust; and other coatings that cannot be removed by wet screening alone. Coarse Material Screw Washer shafts utilise a combination of paddles and spiral screw flights to provide scrubbing, scouring and agitation.

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Why McLanahan Coarse Material Screw Washers

McLanahan offers a wide range of Coarse Material Screw Washers having capacities of 20 to 600 tph. McLanahan Coarse Material Screw Washers can be a solution for many ore, rock or sand washing issues. Our units offer typically provide less downtime, simplified maintenance and more clean product for your highest profitability.

McLanahan Coarse Material Screw Washers feature abrasion-resistant, white iron paddles that provide high 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 it larger amounts of deleterious material, it is still usable despite changing conditions.

The McLanahan screw shaft design keeps operation and maintenance simple on Coarse Material Screw Washers. A 360-degree spiral flight section with wear shoes located at the feed end moves material forward, preventing buildup in that area into a section of scrubbing paddles. Coarse Material Screw Washer shafts are made of extra-heavy steel pipes that have inner and outer renewable and reversible abrasion-resistant hard iron paddles in the scrubbing area. The paddles are followed by heavy-duty steel flights, equipped with bolt-on inner and outer renewable, abrasion-resistant hard iron wear shoes. V-belt drive guarding comes standard for personnel safety. Optional top protective covers are available.

How Coarse Material Screw Washers Work

Coarse Material Screw Washers use paddles in conjunction with screw flights to provide scrubbing, scouring and agitation. The turbulent paddle washing action combines with the rising current water introduced at the bottom of the washer box under the incoming feed to result in the separation of deleterious lighter fractions from the sound aggregate and ore. Lighter fractions, such as clay and floating vegetation, rise to the surface due to the water rising in the box and then overflow the weir located in the back of the washer box. The resulting clean product is then conveyed by the spiral flights to the discharge end of the box.

The selection of Coarse Material Screw Washers is based upon the type of material and contaminants, the desired capacity and the maximum feed size.

McLanahan Coarse Material Screw Washers can be furnished with standard 20 to 40 paddles per shaft. The more paddles that are used, the lower the capacity; however, the washing action is increased due to the fact that paddles do not convey material up the washer box as fast as flights. When using additional paddles, it is also necessary to lower the slope of the box and increase motor horsepower to help convey material to the discharge end.

It is recommended that sand (generally minus 1/4” or 6mm) be screened out prior to using a Coarse Material Screw Washer, as finer material will cushion the washing action.

Popular Applications for Coarse Material Screw Washers

Coarse Material Screw Washers are built primarily to wash crushed stone and gravel, generally ranging from 10mm (3/8") to 100mm (4"). 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 McLanahan Log Washer.

Benefits of McLanahan Coarse Material Screw Washers

  • Low cost
  • Lowest kW (HP) power choice for ore and rock washing
  • McLanahan Twin-Seal Pak submerged rear bearing assembly
  • Shafts flanged at each end to facilitate maintenance are straightened to ensure maximum wear life
  • High brinnell, abrasion-resistant white iron wear shoes and paddles that provide long wear life
  • Shafts utilise paddles at the feed end to provide abrading/washing action and spiral flights for conveying of the material to the discharge
  • Wear collar at the feed end protects the mating shaft flanges and hardware from premature wear

Frequently Asked Questions

What are some key application questions I should have answers for?

You should know the type of clay/silt contamination that needs removed, the ore/rock feed size, the tons per hour feed solids capacity, and the process flow and equipment location of the required washer in your processing plant.

What are some key options to consider?

You can consider front supports, top protective safety covers and a discharge chute as additions to your Coarse Material Screw Washer.

What other technologies should I consider?

In addition to Coarse Material Screw Washers, you can consider Log Washers, Blade MillsRotary ScrubbersTrommel or Vibrating Wash Screens, or a combination Rotary Scrubber Trommel Screen.