Blade Mills

Blade Mills, also known as Aggregate Conditioners, scour, abrade and break down water-soluble silts and deleterious clays from contaminated ores, coarse rock or sand feeds. They are most often placed ahead of wash screens to improve screening efficiencies or in front of other wash equipment to improve the Sand Equivalency (SE).

Despite being very similar in appearance to Coarse Material Screw Washers, Blade Mills process material differently. For instance, all material that enters the box, must exit through the discharge opening as there is no overflow weir. Without an overflow weir, material must be discharged into another piece of process equipment and cannot be put on a conveyor belt.

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Why McLanahan Blade Mills

McLanahan’s extensive experience in washing a wide range of materials started in 1891 when Samuel Calvin McLanahan was granted a patent for a steel shafted ore washing machine he named the Log Washer. As a manufacturer with a wide range of washing equipment, McLanahan can offer the correct solution, not an option of one or two machines others may offer. This combination of experience and choices, along with our global staff’s process application knowledge, makes McLanahan an ideal partner for washing and classifying applications.

McLanahan Blade Mills are available in single- and double-shaft designs depending on capacity requirements. The smallest 508mm (20”) diameter single-shaft Blade Mill can be used for capacities of 20 to 40 tph, while the larger 1370mm (54”) diameter twin shafted machines can be used at capacities ranging from 600 to 1,000 tph. They sit at a slope of zero to five degrees and can achieve very high capacities as a result of the low slope.

Blade Mills from McLanahan feature abrasion-resistant, white iron paddles that are reversible, providing maximum wear life. The ability to reverse paddles keeps material in the box for longer, improving retention time. This flexibility is key if producers want to move the unit or feed it larger amounts of deleterious material.

Design elements help keep operation and maintenance simple on Blade Mills. A 360-degree section of flights and wear shoes located in the feed end can move material forward, preventing buildup in that area. Screw shafts are made of extra-heavy steel pipe shaft with inner and outer renewable, 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 Blade Mill users at its in-house testing laboratory.

How A Blade Mill Works

Blade Mills are designed to do just that — condition. While Blade Mills are very similar in appearance to Coarse Material Screw Washers, they function much differently. They can accept both fine and coarse material, but are not designed to remove tough, plastic clays. They also usually work in conjunction with another type of processing equipment, such as a Classifying Tank or wash screen. The major difference is that any material and water that enters the Blade Mill must exit through the discharge opening located at the bottom of the box opposite the incoming feed end. There is no overflow in this type of unit. 

Using a combination of paddles and flights arranged in alternating format the entire length of the shaft, they scour, abrade and break down deleterious material. The shafts can have different configurations, but mainly have alternating flights and paddles. Blade Mills sit on a slope of 0 to 5 degrees and have higher capacities compared to same size Coarse Material Screw Washers. This is primarily due to the lower machine operating slope of the Blade Mill.

Generally, the amount of water needed for a Blade Mill is an additional third of the weight of material being processed.

Again, a Blade Mill is used where the material needs to be worked and wetted before it enters other wet processing, such as a vibrating screen, Fine Material Screw Washer, Sand Classifying Tank or further wet processing.

Applications

Blade Mills are predominantly used in washing contaminated construction aggregate that includes rock, rock and sand and dewatered sand that needs scrubbed due to soundness or sand equivalency requirements. Many non-aggregate hard ores that have water soluble clays and silts can also be effectively washed as part of a wet processing material handling system where downstream particle sizing and dewatering equipment is used.

If the rock or ore has tough, plastic, fine-grained sticky clays or feed sizes larger than 100mm or 4 “, McLanahan offers other equipment options. 

Blade Mill Features & Benefits

  • The use of a Blade Mill, if suited for the duty of service, will be the lowest cost machine and lowest kW (HP) power choice for ore and rock washing over most other options
  • McLanahan Twin-Seal Pak submerged rear bearing assembly incorporates Caterpillar Duo-Cone® seals that keep water and even the smallest particles from reaching the bearing. This is a far greater rear bearing assembly design over any competitor’s offer.
  • 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 provide long wear life
  • Shafts utilise staggered wear shoe and paddle configuration to abrade and convey material
  • Wear collar at feed end protects mating shaft flanges and hardware from premature wear

Frequently Asked Questions

What are the differences between a Blade Mill and a Coarse Material Screw Washer?

  1. Installation slope: Blade Mills sit at 0-5 degrees, while  Coarse Material Screw Washers sit at 12-18 degrees.

  2. A Coarse Material Washer, because of installation, has a slurry overflow of water and liberated silts and clay, whereas a Blade Mill does not.
  3. A Coarse Material Washer typically has paddles only at the feed end of the shaft, where a Blade Mill shaft has alternating spiral flights and paddles.
  4. Feed to a Coarse Material Screw Washer is typically +5mm or 4 mesh, whereas the feed to a Blade Mill can have -5mm solids material.

How much does it cost?

Contact McLanahan or your nearest authorised local dealer not only for pricing, but for discussions on suitability and use for your application.

Key options to consider?

  • The type of clay/silt contamination that needs removed 
  • The ore/rock feed size
  • The tons per hour feed solids capacity
  • The process flow and equipment location of required washer in your processing plant