McLanahan Offers Classifying Tank Based Sand Plants with Fine Material Screws or Dewatering Screens

Sand Classifying Tanks have been a staple in the construction aggregates industry for more than 50 years. Also known as water scalping tanks, Classifying Tanks handle large amounts of water efficiently and offer the ability to create multiple specification products from one feed.

Classifying Tanks are divided into sections known as stations. As the sand slurry enters the sand tank, product sized sand particles are separated are separated in successive sizes down the length of the tank, with coarse particles settling in the stations at the front of the tank, medium size particles settling in the middle and fine particles settling in the stations at the end of the tank. Valves in each station discharge sand to reblend the particles to a certain specification via a collecting flume and then discharge to dewatering equipment, such as Fine Material Screw Washers or Dewatering Screens, ahead of stockpiling. 


Traditionally, Classifying Tanks are used in conjunction with Fine Material Screw Washers, which provide partial dewatering of a final product for stockpiling. Sand screws are also a staple in the industry and are great for handling fluctuations in Classifying Tank underflow.

While sand screws are still the equipment of choice for handling Classifying Tank underflow, McLanahan’s Director of North America Sales, Rick Madara, said as the high level of product efficiencies are recognized, Dewatering Screens are becoming more and more popular in this application.

“Even though it is being recognized as new technology, it really isn’t,” explained Madara. “We’ve been making Ultra Sand Plants — or Dewatering Screens Plants — for a very long time, and we’ve been installing them after sand tanks for almost 20 years. 

“For years, they said you couldn’t put a Dewatering Screen underneath a sand tank underflow, but we had a lot of smart people come up with a plan and we did it, and we did it successfully, and we’ve been doing it ever since.”

Ultra Sand Plants, which are a process utilizing a Hydrocyclone or Hydrocyclones and Dewatering Screen, produce a consistent drip-free product in the range of 10-15% moisture. This allows for less stockpiling time and quicker sale, which is ideal for producers who need to move a lot of product quickly. Dewatering Screen plants also shine when fine specialty sands are required.

“Ninety-nine percent of the time, either a Fine Material Screw Washer or a USP will work fine,” Madara shared. “I’d say, 80% of the time it comes down to comfort level. People are very comfortable using screw washers, but there are cases where it makes sense to use a Dewatering Screen. I would say the producer has to look at the value each brings, and we’ll walk them through that. In most cases, from a product standpoint, you can’t go wrong using either one.”

The McLanahan Advantage

Because McLanahan has been making Classifying Tanks, Fine Material Screw Washers and Dewatering Screens for decades, the company passes that knowledge and experience onto the customer in terms of helping them choose the right equipment to produce their desired product.

By gaining a thorough understanding of the application and testing materials in its in-house lab, McLanahan is able to provide the advantages and disadvantages of using sand screws and Dewatering Screens with sand tanks so that the customer can be successful in their endeavors.

“We’re not successful unless the customer is successful, so we want to make sure they’re successful with whatever it is they’re trying to do,” Madara said. “We have so much experience here within the company that we can make sure that whatever they’re going to get is going to give them exactly what they need.”

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