Tech Tip: Low Water Sand Processing

Water shortages are worsening. Environmental regulations are tightening. Sustainable practices in sand processing have never been more important – not only to protectand preserve valuable resources – but also to maintain ongoing profitability.

How do you become water-wise? How do you practice and maintain low water sand processing? While there is no quick fix or one-size-fits-all solution, there are key steps that lead to reduced water use, maximum recovery, and overall efficient operation.

Based upon the expertise of veteran mineral wet process guru, John Bennington, we’ll outline the six biggest things you must know about low water sand processing.

3. Understand Water Efficiency is Not a Quick Fix

To minimize pond use and maintenance, operations may turn to mechanical solutions such as filter presses, cyclones, water clarifiers, fines recovery systems, and more. While each has its advantages and disadvantages in an application, there is rarely just one quick fix, or just one piece of equipment recommended for any given situation. It’s usually a good idea to have more than one stage in an effective mechanical solution.

For example, it’s common to see producers placing a cyclone fines recovery plant in the middle of the waste stream before it’s discharged to the pond. Producers may view this as an easy, simple solution. However, consider that most cyclones generally keep only about half of the minus-200-mesh material from going to the pond. Consequently, much of the material that goes to the pond is ultra-fine. These particles are not easily bailed, as they simply flow around the excavator bucket. Someone once described this situation as “bailing smoke.” This supports the fact that quick fixes such as these can make the problem worse.

4. Incorporate Low Water Washing Technology

More and more operations are faced with severely limited water resources to pull from wells or from the environment. At issue is the amount of water required for conventional washing methods and the need for alternative and economical low water washing solutions.

As to conventional methods, a sand screw needs 50-gallons per minute of water for every ton of minus-200-mesh in the feed. Even if an operation is only running at 100-tons per hour, and their minus-200-mesh is at 15% – that is 15-tons of fines requiring 750-gallons per minute of water to adequately lift the silt over the weirs of the screw. That’s a lot of water for most crushing operations.

5. Use Dewatering Washers For Fines Recovery

For many operations, maximum water recovery is job one. They must achieve as much of a closed loop as possible within the wash plant. Consider that a standard sand screw will put about a gallon of water per minute/per ton into the stockpile. That water is a net loss. It’s not discharging into a pond or recycling back into the system. It’s either going into a truck or evaporating on the ground.

As a result, Superior has designed its Aggredry® Dewatering Washer to maximize recovery by capturing, recirculating, and reusing water within the system. Operations can cut water usage by 50% or more, when compared to conventional methods.