A wash plant can range from a relatively simple system consisting of a single machine costing only a few thousand to a complete, integrated washing solution worth several million. The overall investment depends on several factors, including the condition of the feed material, plant capacity, water management requirements, site restrictions and the number of processing stages required.
Understanding these factors before selecting equipment will help ensure your investment delivers the best long-term return.
Types Of Washing Equipment
Rather than focusing on a single purchase price, it is helpful to think about wash plant investment in terms of the amount of processing required.
A simple sand washing application may only require a Fine Material Screw Washer and supporting equipment, while a more complex aggregate washing operation may include feed preparation equipment, sizing screens, pumps, hydrocyclones, dewatering equipment, water recycling systems and complete tailings management.
Tasks of wash plants include:
- Feed preparation – to prepare a raw feed for processing by breaking down and removing clays and surface contamination
- Sizing – to screen the raw feed to reject the oversized material to further processing or waste
- Pumping – to transfer the slurry material from one process to the next
- Desliming – to remove liberated ultra-fine material before classification
- Wet classifying – to separate particles based on size or specific gravity
- Organics removal – to classify material based on specific gravity to remove organic material such as lignite
- Densifying and Dewatering – to concentrate a slurry to a specific density to feed to downstream equipment and to remove moisture from a product for improved stockpiling and quicker sale
- Effluent treatment – to recover process liquid from the waste stream for reuse in the wet plant
- Waste solids management – to separate liquids from the solids in a waste steam, where the liquid can be reused in the process plant and the remaining solids are stackable, to reduce or eliminate settling ponds
- Or a combination of any or all of the above processes
Although adding more equipment increases the initial capital investment, it can also improve operating efficiency, reduce maintenance, help to recover more saleable material and significantly lower long-term operating costs.
For Feed Preparation
Feed preparation is the first stage of many wash plants. The objective is to remove contaminants such as clay, dirt, coatings and other deleterious materials before classification begins. Effective feed preparation improves downstream performance and helps produce cleaner, higher-quality products.
Attrition Cells | $$
Attrition Cells scrub the surface of particles to liberate and break down clays, oxides, chemicals and other contaminants to improve a sand’s durability and turbidity. They accept a top size of ½” (12 mm) and can handle high plasticity clays.
Often used in the feed preparation stage if multiple products are being processed, Attrition Cells can be found at any stage of the wet process to scrub material to improve the final product.
Blade Mills | $$
Blade Mills are designed to liberate light, loamy clay or dirt from either coarse rock and/or sand before further processing. Blade Mills can be placed ahead of a wash screen to result in cleaner rock or ore, or ahead of a Sand Classifying tank or Fine Material Screw Washer in fine sand applications.
Blade Mills are not designed to remove tough, plastic clay or high percentages of clay. They usually work in conjunction with another type of processing equipment such as a Sand Classifying Tank or Wash Screen.
Coarse Material Screw Washers | $ – $$
Coarse Material Screw Washers are designed to wash crushed stone and gravel ranging from 3/8” to 4” (9.5 mm to 102 mm). They effectively remove light loamy clays, dirt crusher dust and coatings that cannot be removed by wet screening alone.
They also can be used to take out floating vegetation and soft aggregate, although all vegetation and water-logged sticks may not be removed completely. Coarse Material Screw Washers are not intended to remove tough plastic clay.
Log Washers | $$
Log Washers remove tough, plastic clay from natural and crushed gravel, crushed stone and ore feeds. Log Washers must have a controlled top size, with the larger machine sizes being able to accept a feed material up to 6” (152 mm) cubed.
It is recommended that the sand-sized fraction be removed prior to the Log Washer, since the finer material tends to cushion the washing action. This sand fraction should only be fed to the Log Washer when severe washing of fines is required.
When processing fines, it is necessary to capture the overflow of the unit to save this fraction for further processing or close off the overflow opening so that material is carried the full length of the box for scouring of the fines.
Rotary Scrubbers | $$$ – $$$$
Rotary Scrubbers are designed primarily for the removal of loam and light clays and soft, soluble waste materials from aggregates, stone and ore. They are not intended for use in applications where tough plastic clays are contaminating the material to be cleaned.
When these tough clays are fed to a Scrubber, the clay particles have a tendency to pelletize through the tumbling action of the material and, instead of breaking down, may actually increase in size.
Rotary Scrubbers can accept large feed sizes, up to 10-12” (254-301 mm), and they are sometimes used as a primary washer before any crusher or screening is accomplished.
For special washing and screening applications, a Scrubber Screen (a combination of Rotary Scrubber and Rotary Trommel Screen) can be effective.
For Sizing
Once contaminants have been removed during feed preparation, separating material into the required size fractions is required. Accurate sizing ensures downstream equipment receives the correct feed and helps maximise plant efficiency while producing products that meet specification.
Vibratory Screens | $ – $$
Vibratory Screens are used to separate material according to size. These can be horizontal or inclined with a varying number of screen decks depending on the application. In a wash plant, Vibratory Screens are used to screen the raw feed into fractions appropriate for downstream processing.
For Pumping
Moving material through the washing process is essential to maintaining plant performance. In most applications, slurry pumps provide a reliable means of transporting material between each stage of the process.
Slurry Pumps | $ – $$
Slurry Pumps are used to transfer material, in the form of a slurry, from one process to the next. Gravity-fed plants can be an alternate option, but Slurry Pumps are able to capture all saleable materials that may be lost to waste in gravity fed operations.
For Desliming
Before classification begins, some applications benefit from removing liberated ultra-fine material. Desliming improves the efficiency of downstream equipment and helps produce cleaner final products.
Hydrocyclones | $
Hydrocyclones are the preferred method for removing ultra-fine material before the classification process due to their high shear and efficiency. Adding a Hydrocyclone or Hydrocyclones before a Sand Classifying Tank or Screw Washer in feeds with high fines can improve the performance of these machines.
Feed Regulating Sumps can also be used in high volume applications, such as dredge operations. These devices remove fine material from the feed by allowing it to settle in the base.
For Wet Classification
Wet classification separates particles according to size or weight, allowing producers to manufacture one or multiple products that meet demanding specifications.
Several types of equipment can perform this task depending on the material characteristics and the desired end product.
Sand Classifying Tanks | $$
Sand Classifying Tanks are used to remove excess water in a dilute slurry feed, to classify material by removing an excess of intermediate sieve sizes, to retain finer mesh sizes and to make multiple products from a single feed material.
Sand Tanks can work with either a slurry or dry feed. They handle gradation swings in the average plant while minimizing waste. The discharge from a Sand Tank must be further processed in a Fine Material Screw Washer or Dewatering Screen.
Sand Tanks are generally used in sand and gravel plants, as well as manufactured crushed stone sand plants.
An optional rising current classifier can be installed in the first two or three stations of a sand tank. The rising current classification improves sand classification by injecting fresh water near the slurry feed entry to deter the settling of fine sand until later in the sand tanks. This allows for higher sand product yields when re-blending coarse, intermediate and fine sand for construction grade specifications.
Fine Material Screw Washers | $ – $$
Fine Material Screw Washers are primarily used to dewater, classify and wash minus 3/8” (9.5 mm) sand or fine minerals. These machines are designed to accept feeds from a belt conveyor or slurry feeds from washing vibrating screens, Sand Tanks, Hydrosizers®, Hydrocyclones or other Fine Material Screw Washers.
The product-sized sand sinks to the bottom of the Fine Material Screw Washer washer box and is conveyed up the incline toward the discharge, while fine particles float over the weirs with the overflow liquid.
Hydrosizers® | $$
Hydrosizers® are used to make extremely sharp cuts between 150 and 30 mesh using the hindered settling principle. These devices accept feed sizes up to ¼” (6 mm) and handle wide fluctuations in solids feed rate without affecting performance.
Hydrosizers® have the highest efficiency of all wet gravity equipment in a smaller footprint and are typically used for creating specialty sands like glass, frac, filter, sports and foundry.
Hydrocyclones | $
Hydrocyclones can be used in many different parts of a wash plant. They can be used for desliming, as aforementioned, but they (and their variant the Separator™) can also be used for classification of sizes 140 mesh and finer.
In fines recovery applications, Hydrocyclones can capture down to 400 mesh of a typical 2.7 SG material.
Hydrocyclones have no moving parts, so they generally require a pump in order to function, which is an additional cost to consider.
For Organics Removal
Some applications require lightweight organic contaminants to be removed from the final product in order to meet specification.
Hydrosizers® and Lites-Out™ Flat Bottom Classifiers | $$
Hydrosizers® and Lites-Out™ Flat Bottom Classifiers are designed to separate material according to specific gravity, making them highly effective for removing lightweight organic contaminants from sand streams finer than 4 mesh.
Like Hydrosizers®, Flat Bottom Classifiers utilise hindered settling and a dense fluidised bed of near-sized sand. Lightweight materials float and are discharged as waste, while the heavier, saleable sand particles pass through the bed for collection.
This process improves final product quality while helping producers consistently meet customer specifications.
For Densifying and Dewatering
After classification, many washing applications require material to be concentrated or dewatered before stockpiling or further processing. Removing excess moisture improves handling, reduces transport costs and allows products to be sold sooner.
Separators™ and Hydrocyclones | $
When dilute slurries need to be concentrated before being fed to equipment like Hydrosizers® or Attrition Cells, Separators™ are also often used.
Separators™ are modified Hydrocyclones that offer the ability to control the density of the underflow discharge. In this way, it can provide a denser slurry when necessary, either before downstream process equipment or for stockpiling directly.
To remove moisture from a final product, a Fine Material Screw Washer, Separator™ or Dewatering Screen can be used.
Fine Material Screw Washers | $ – $$
In addition to washing and classifying sand, Fine Material Screw Washers also provide effective dewatering.
As material is conveyed up the rotating inclined screw shafts, it will typically discharge around 20% moisture from the sand screw.
Dewatering Screens | $
Dewatering Screens offer the most moisture removal, discharging products at as low as 7% moisture. These devices are used in a wide variety of applications to provide a drip-free product that is stackable and conveyable for improved stockpile management and housekeeping.
The addition of a spray bar on a Dewatering Screen to wash out excess fines also helps to improve sand equivalency in the final product.
For Effluent Treatment
Water is one of the most valuable resources in any washing operation. Recovering and reusing process water not only reduces operating costs but also improves site sustainability and minimizes environmental impact. Water reusage is often one of the most potential cost saving activities when considering these operations.
Thickeners | $$$ – $$$$
Though not necessarily a part of the washing process, Thickeners are used to recover immediately reusable process water, up to 85%, for reuse in the wet plant. With water being a valuable resource as well as an important part of the wet process, recovering as much as possible for reuse helps improve site sustainability, as well as reduces water buying costs and reduces the amount of material reporting to the settling pond.
For Waste Solids Management
Managing waste efficiently has become an increasingly important consideration when designing modern wash plants. Recovering additional saleable material while reducing the reliance on settling ponds can improve both profitability and sustainability. A washing process is inevitably going to contain a waste stream containing the water and liberated deleterious material, but minimising this is where some of the biggest savings in costs can occur.
UltraFINES Recovery Plants | $$
An UltraFINES Recovery Plant containing a Hydrocyclone and Dewatering Screen can be used to capture fine particles in the waste stream to reduce the load on downstream equipment and/or the amount of material reporting to the settling pond, as well as create a potential saleable product from the recovered material.
Filter Presses | $$$ – $$$$
Following the Thickener which, as previously mentioned, can be used to remove up to 85% of the water from the waste stream for reuse, a Filter Press separates the remaining solids from the process water.
The McLanahan Filter Press can also be fitted with the QUICKCHANGE™ system, a patents-pending rapid filter cloth changeout system that is transforming filter press maintenance. This innovative technology streamlines filter cloth replacement and filter plate inspection, allowing you to maximize efficiency and reduce downtime on your site.
The recovered water can be returned to the wash plant, while the remaining solids are discharged as a stackable, conveyable filter cake that is significantly easier to manage than slurry.
In many operations, this approach reduces or even eliminates the need for large settling ponds while lowering ongoing maintenance and housekeeping costs.
So, how much does a wash plant cost?
The simple fact is that you will rarely be able to receive one blanket answer for this question. Selecting the correct equipment is only one part of determining the total investment – there are many other factors such as configuration, structural design, erection and additional site develop, that will factor into the cost of your wash plant. The overall plant configuration also has a significant influence on both capital costs and long-term operating efficiency.
Stationary Wash Plants | $$ – $$$$
Stationary wash plants are typically the preferred solution for permanent, high-capacity operations. A stationary plant may not make sense for a site with multiple locations or a site with a short lifespan on reserves where ROI will be realised sooner with a modular or portable plant.
Modular Wash Plants | Discovery Wash Plant | $$$ – $$$$
Modular wash plants range from an entry-level size such as the new McLanahan Discovery Wash Plant to a full-size UltraWASH Plant. Deciding which style of plant you need is a balance between performance and installation speed.
Pre-engineered modules reduce installation time and civil engineering requirements while providing many of the benefits of a permanent washing solution. They are often a cost-effective option for producers looking to minimise project timelines without sacrificing performance. The Discovery Wash Plant, for example, can be set up within 2-3 days and only utilises 3 flatbeds for transport, further reducing costs of installation and build.
The negative aspect to the modular plant is that it can be limited in throughput.
McLanahan’s Discovery Wash Plant is a compact, modular solution designed for small operations. It delivers the washing capability needed to upgrade product quality and unlock new market opportunities. Its quick setup, intuitive operation and efficient layout make it an ideal choice for producers looking to add wet processing without the complexity of a traditional stationary wash plant.
Reducing The Total Cost Of Ownership
While the purchase price of a wash plant is an important consideration, it represents only one part of the overall investment.
Operating costs, maintenance requirements, water consumption and the recovery of additional saleable material all influence the total cost throughout the life of the plant.
For example, sites operating in regions where water is scarce or expensive may benefit significantly from incorporating a Thickener or Filter Press into the design. Although these systems increase the initial investment, they can substantially reduce water costs while in operation.
Similarly, adding equipment such as an UltraFINES Recovery Plant, Thickener or Filter Press can dramatically reduce the amount of solids. This decreases reliance on settling ponds, reduces housekeeping requirements and can even generate additional revenue by recovering saleable material that would otherwise be lost.
Mechanical Sampling Systems | $ – $$
You many also want to invest in a mechanical sampling system. Mechanical Sampling Systems are used for collecting a final product from a conveyor belt or product stream without having to stop the flow of material. Though not part of the washing process itself, these automatic Sampling Systems are a great device for ensuring final products are meeting specifications.
Additional equipment should also be considered when budgeting for a wash plant. Supporting structures, conveyors, pumps, pipelines and stockpile areas are often not included within the headline equipment price but can represent a significant proportion of the total project cost.
Material handling requirements, including the number of products being produced, stockpile locations and conveying distances, should all be evaluated during design stage to ensure the final plant layout delivers the most efficient operation.
Conclusion
There is no single answer to the question, "How much does a wash plant cost?"
The cost of a wash plant depends largely on the material you are processing and your production goals. The material being processed and capacity required will dictate the size and therefore investment to be made in equipment (larger equipment for higher capacities will cost more money), as well as how many pieces of equipment are required.
You also need to factor site restrictions and/or site sustainability into the design of your wash plant, which will have an impact on upfront costs. Producers should consider regional planning and legislation requirements that can often add costs, many of which will change or evolve in coming years.
While a simple washing application may only require a handful of machines, more complex operations can benefit from fully integrated washing systems that maximize product recovery, improve water reuse and reduce long-term operating costs.
The most effective way to determine the right solution is through material testing and consultation with experienced process engineers. By working with a team who understands both the material consistency and the site's long-term objectives, producers can design a wash plant that delivers the performance, product quality and return on investment their operation demands.
