Why McLanahan Sand Washing Plants
McLanahan is best known for creating process solutions to address the specific needs of each customer's application. We have one of the largest ranges of robust, field-proven equipment, and we are constantly innovating. Our background and expertise in applications is second to none.
Depending on the application, McLanahan can perform lab scale tests on materials, including sieve analysis, percent solids, attrition scrubbing, sink/float, sand equivalency and durability, Hydrosizer™ based classification, static and dynamic flocculation/settling and Filter Press testing.
With our proprietary simulations, in-house lab and industry expertise, you get a plant designed specifically for your site with capacities to match your need. Our expertise is the envy of the industry, so when you couple this with one of the largest ranges of equipment offerings, we can offer a solution.
How Sand Washing Plants Work
Sand Washing Plants covers a variety of processes to get the sand from the raw state to a finished state. These process can include:
- Feed Preparation - Before the raw feed can be processed, it must be prepared using a combination of Attrition Cells, Blade Mills, Coarse Material Screw Washers, Log Washers and Rotary Scrubbers. The objective is to bring all materials into suspension, essentially breaking down any clays and clay-bound materials and removing superficial surface contamination.
- Sizing – Prior to and immediately after the feed preparation step, the raw feed must be screened into fractions appropriate for both the downstream process and the products to be produced. Vibratory Screens are typically used.
- Pumping – Centrifugal Slurry Pumps are the preferred means by which slurry is transferred from one plant/process to the next. Pumps are also used for effluent disposal. Although there can be resistance to using a pump over a gravity-fed unit, a gravity-fed unit may not be able to capture saleable materials. These losses go straight to waste and will end up costing you money in the long term.
- Desliming - If a significant amount of liberated ultra-fine material is present in the feed, it is typically desirable to remove this deleterious fraction before classification. Classification efficiency can be adversely impacted by high levels of suspended clays, leading to losses of saleable materials and dirty products. Cyclones are the preferred desliming device due to their high shear and efficient classification. Feed Regulating Sumps are also very appropriate especially where there are high volumes such as would be found in dredging applications. Their controlled overflow can reduce the power consumption for pumping to downstream classification. Occasionally, desliming or simply washing is all that is needed to create the final product by removing the <75µm (<200 mesh) down to a certain level, such as 3-5% passing.
- Classifying – This is the process of separating particulates from one another based on either size or specific gravity. In sand washing, this applies to the <4mesh (<5mm) particulates. The procedure may involve making single sharp separations with our Hydrosizer™, or multiple size classifications with our Classifying Tanks. Where a specialty sand is being produced, such as for glass, frac, sports, filter, foundry, etc., a Hydrosizer™ provides the accuracy needed for the splits in product gradation. Cyclones and Separators™ are also classification devices operating in the 140mesh (105µm) and finer size separation range typically finer than that where a Hydrosizer might be used.
- Deligniting/Organics Removal - This process is the classification of materials based on their specific gravity. In an aggregate application, depending on the overall process design, either a Hydrosizer™ or a LitesOut™ is used to reject +50 x 4mesh organics of 1.4 – 1.8 SG. We use the ASTM C123 test for lightweight materials where a heavy liquid is used to define the specific gravity of the contaminant. Under some circumstances where the specific gravity differential between the sand and the lignite is marginal, we may run a test in our lab to evaluate dense medium separation as in a Hydrosizer™. It should always be understood that final products will not be lignite-free but will pass based on ASTM C123.
- Densifying and Dewatering – Certain types of equipment, like Hydrosizers and Attrition Cells, require a dilute slurry to be concentrated. Cyclones or Separators™ are most commonly used for this purpose. Separators™ are especially suited for this duty with the ability to dial in and under flow density. In the case of dewatering, Fine Material Screws, Dewatering Screens or Separators™ are the most common devices. The lowest moisture content, by far, is obtained with a Dewatering Screen. With improved safety (less cleanup around the conveyors), better housekeeping (almost no water drainage from the stockpile) and more immediate availability, Dewatering Screens have become the equipment of choice for final product dewatering.
- Effluent Treatment – Water is a very valuable commodity, so it is becoming a requirement to include a water recovery circuit as part of any permitting process. The device most common for this purpose is a Thickener. In most cases, 85% of the process water can be recovered for reuse. The most cost-effective storage method is a dedicated water tank to reduce the percolation and evaporation losses associated with ponds. These tanks also save on the power requirement to pump the water out and back.
- Waste Solids Management – While Thickeners can recover process water, the underflow is relatively dilute and is typically be pumped to containment ponds. To finish off the sand washing process and have the waste solids in a conveyable and stackable condition, Filter Presses are typically employed.
- Sampling - Every system requires monitoring and sampling to provide the best results. McLanahan can design a sampling system up front to focus on the key areas. The ability to react faster to process changes helps eliminate waste, improve product quality and troubleshoot problems.
Popular Applications for Sand Washing Plants
Sand Washing comes in many forms and covers a range of feed and products produced, including construction aggregates such as concrete, asphalt, mason, mortar, and plaster sands; sports sands such as for golf courses, ball parks, and race courses; industrial sands, such as glass, filter, foundry, and frac; speciality sands and materials such as anti-skid, roofing granules; deligniting/organics removal; and soils washing for environmental projects.
Benefits of McLanahan Sand Washing Plants
- Designed with field proven, state-of-the-art equipment
- Improved yield from your deposit
- Lab scale testing for optimal eqiupment configuration
- Big picture view with experience implementation
- Dedicated project management
- Field Service Team for startups and troubleshooting
Frequently Asked Questions
With the range of Sand Plant designs, how do I select the right one?
First, consider the following questions: What do you have? What do you want to make? If the answer is a very specialized gradation and a difficult natural sand deposit, then consider a Recipe Plant. If the answer is a manufactured sand and you are making concrete sand all day every day, then an Ultra Sand Plant or Modular Wash Plant may be your answer.
Many other factors, such as available investment, local competition and expanding markets, will influence this decision. Through a process of elimination starting with the simplest configuration, McLanahan’s experienced personnel will guide you through to the best options.
What can an Ultra Sand Plant do for me?
Ultra Sand Plants, which utilize Dewatering Screens, Pumps and Cyclones, offer greater separation efficiency and provide a higher product yield that can be reused almost immediately due to the effectiveness of the Dewatering Screen. Ultra Sand Plants are commonly used to wash and dewater industrial and specialty sands, as well as asphalt, concrete and masonry sands.
Why should I consider a Recipe Sand Plant?
For high-quality sand that meets strict specifications, look no further than McLanahan Recipe Sand Plants. These sand plants make use of every grain of sand to offer customized blending for concrete, foundry, glass and plaster sands. The resulting sand product is consistent, uniform and will meet even the tightest of specifications.
What are the benefits of In-Line Blending Sand Plants?
McLanahan In-Line Blending Sand Plants provide high product yields, offer flexible blending options, produce drier products and improve product consistency. They are simple to operate, create accurate splits and are field-proven.
How can a Frac Sand Plant benefit my operation?
McLanahan designs each of its Frac Sand Plants to meet the specific needs of each customer. Using field-proven McLanahan equipment, Frac Sand Plants can be designed for classifying, desliming, dewatering, pumping, scrubbing, sizing, tailings management and waste solids management. McLanahan Frac Sand Plants are engineered to make the critical separations required for frac sand. They produce the highest product yield at the lowest moisture.
How do Classifying Tank Based Sand Plants Work?
Classifying Tank Based Sand Plants can create multiple products from a single feed as well as remove slimes and excess water. Feed material enters the Sand Classifying Tank first, and sand grains settle in sections according to size down the length of the tank. Valves at the bottom of each section release the grains into one of several flumes used to create a primary, secondary or tertiary product, depending on the application. The discharged products are then dewatered by Dewatering Screens and/or Fine Material Screw Washers. The addition of Cyclones and/or rising current water can be used to deslime the feed.
What equipment is included in an Industrial Sand Plant?
McLanahan Industrial Sand Plants are designed with a combination of McLanahan equipment to provide extremely sharp classification of various industrial sands. This equipment can include Attrition Cells, Dewatering Screens, Hydrocyclones, Hydrosizers™, Filter Presses, Fine Material Screw Washers, Pumps, Separators and Thickeners.
Will a Portable Plant limit what I can do?
Although Portable Plants, which can be wheel-mounted or skid-based to provide an ease of transport, are limited in capacity, they do not limit the process. Portable Sand Plants can be used for classifying, dewatering, sizing and removing oversize and organics from feeds to produce aggregates, construction and demolition materials, and specialty sands.
What can I process with a Modular Wash Plant?
Modular Wash Plants are a low-cost, rapidly available option for processing natural, uniform deposits with sand/aggregate ratios near 40/60 or 60/40.
What are the benefits of Ultra Fines Recovery Plants?
McLanahan Ultra Fines Recovery Plants can recover +400 mesh material for use in many industries. UFRs are especially well-suited in the aggregates industry for effluent streams containing <100 mesh fractions and for recovering valuable coal from effluent streams in the coal industry.