Classifying Tank Based Sand Plants

Sand Classifying Tanks remove excess water and slimes or undesirable grain sizes from minus 4 mesh (<5mm) natural or crushed sand feeds. They are typically used to classify sand for most construction specifications by removing an excess of certain intermediate mesh sizes. Sand Classifying Tanks are often used to classify multiple products from a single sand feed.

Sand Classifying Tanks can be combined with Hydrocylcones, Screw Washers and Dewatering Screens to create entire sand washing plants. Hydrocyclones can be used to deslime the feed prior to the Sand Classifying Tank. Dewatering Screens can help remove moisture from the moisture final products. These can be adapted straight onto the discharge from the Sand Classifying Tank or fed via a Screw Washer to provide more flexibility in plant configuration and provide a potentially slightly improved final product moisture than a Dewatering Screen alone.

In some cases, organics removal systems can be adapted to the Sand Classifying Tank to meet certain product specs in areas where lignite is prevalent. These Lites-Out™ systems can be fed from the product discharge flume of the tank and can be configured to be taken offline when non-critical products are being produced. 

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Why McLanahan Sand Classifying Tank Based Sand Plants

McLanahan Corporation began manufacturing manually adjusted Sand Classifying Tanks in the the 1950s and automated units since the 1960s using computer punch cards in a card reader system. McLanahan was the first manufacturer to offer automated Sand Tanks with programmable logic controllers in the early 1980s. 

McLanahan offers other classification equipment, including Hydrosizers™. These units are widely used in wet processing sand systems when a sharp, single cut is needed ranging from 100 (150 mesh) to 800 microns (20 mesh).

Today, McLanahan Sand Manager® Classifying Tanks have two levels of automation using Allen Bradley automation that provides remote monitoring and adjustment from anywhere you are.

McLanahan's ability to integrate the Classifying Tank with all the other field-tested equipment McLanahan has to offer provides an ideal fit for sand production.

How Sand Classifying Tank Based Sand Plants Work

Water and sand sized fractions enter the feed end of the Sand Classifying Tank. As the material passes down the long narrow setting area, coarse sand grains settle first and finer grains settle in successive sizes down the length of the tank. Stall paddles sense the buildup of sand fractions and the PLC determines the best use of the sand. Hydraulic controls at the top of the Sand Classifying Tank operate discharge valves at the bottom of the tank, sending the fractions to one of three flumes as concrete sand, a second spec sand and a control sand. Discharges from the Sand Classifying Tank can be dewatered by Fine Material Screws, Dewatering Screens or a combination of both.

The process is simple and reliable and proven over many years. Sand Classifying Tanks need a consistent volume because increases and decreases in flow will change the deposition of particle sizes, resulting in inconsistencies in the final products. In cases of variable feed, a McLanahan Feed Regulating Sump can provide this consistency.

Other refinements that can be used with the Sand Classifying Tanks are Hydrocyclones to deslime the feed and rising current water to help displace silts from the first stations. Hydrosizers or Lites-Out systems are used to reduce organic/lignite content.

Classifying Tank Based Sand Plants find their place most often in natural sand deposits with excesses of certain size fractions. Sand Classifying Tanks are also useful for limited specialty products where an operator can dial in a different product using the PLC, and are capable of producing some sports sands and other products with wider tolerances.

Benefits of McLanahan Classifying Tank Based Sand Plants

  • Create multiple in-spec products from one machine
  • Patented mechanicals to simplify maintenance
  • Automated operation — PLC with local HMI
  • Low operator involvement
  • Specialty products can be produced
  • Available in portable and semi-portable plants with Fine Material Double Screw Washers

Frequently Asked Questions

Classifying Tanks are considered old technology — why do you still promote them?

Certainly Classifying Tanks have been around for a long time, but that doesn’t make them obsolete. McLanahan manufactures all the sand-washing technologies available and offers the best solution, not just modular systems or the product we have on the floor at any one time. The Sand Classifying Tank is a very viable, very reliable technology for certain applications. Many major corporations and private companies have recently invested in this technology with excellent ROI not available with other machinery.

What about all that maintenance?

Decisions made at the beginning of the process of defining the machine can improve the long-term performance of the Sand Classifying Tank — most importantly, consideration needs to be given to the product’s abrasiveness. Wear materials added in areas such as the feed box, discharge flumes and hard metal valves and seats for the first stations can significantly change the long-term profile of maintenance cost.  Sand Classifying Tanks are simple pieces of equipment, and maintenance tasks are also relatively simple.

Can I use my existing Classifying Tank?

McLanahan has configured plants around existing equipment to improve performance, including adding desliming Hydrocyclones, organics removal and replacing or supplementing Screw Washers. The preference is always to start with a clean slate, but if the existing Sand Classifying Tank is in a condition that will allow it to function reliably,  then why not use it. However, it is not viable to piece together plants with one brand of pump, an old sump, some off-brand Hydrocyclones from the boneyard, and a secondhand Dewatering Screen — that is simply a recipe for long-term frustration and dissatisfaction on both sides of the checkbook.