Sand washing has never been a one-solution-fits-all process. There are many different types of sand and many different types of sources and deposits. Likewise, there are many different types of sand processing equipment and systems. Some common systems include sand screws (or Fine Material Washers) and cyclones or a combination of the two.
Feed enters a pool of water in the washing area at the back of the machine. Coarse, heavier particles sink to the bottom of the tub, while smaller, lighter particles float to the surface and discharge with the wastewater over the three weirs lining the sides of the washer tub.
The coarser material is conveyed out of the washer tub by the rotating screw shafts and travels up the incline toward the discharge end. As sand progresses to the elevated discharge point, water in the material leaves the sand and flows back toward the rear of the washer box, where it overflows the weirs.
Cyclones are comprised of hollow conical sections. Feed material in a slurry enters near the top of the cyclone at a designated pressure and volume. Larger particles are flung/spun to the outer edges of the cyclone by centrifugal forces and make their way toward the discharge cone (or apex) at the bottom. Fine particles and water remaining the center of the cyclone spin upward toward the overflow from the pressure of the slurry of pumped solids.
Sand screws and cyclones are fundamentally different systems that are good at different things. Sand screws tolerate changes in feed exceptionally well and dewater abrasive, coarse aggregate with low wear, but they do not capture ultra-fine particles. Properly sized cyclone systems are great at capturing fine particles, but they are sensitive to irregular feed and oversize particles.
When deciding which is the right sand washing solution for your application, you have to first consider how sand screws and cyclones work, as well as what is happening to the material as it goes through each piece of equipment. Lets look at some of the different characteristics of sand screws and separators.
Slurry pumps commonly run at speeds ranging from 600 to 1,000 rpm, which means the material that enters the cyclone is moving very fast. This speed allows the cyclone to spin out fine particles precisely and efficiently.
Fine Material Washers, on the other hand, operate much slower than cyclones, at speeds typically ranging from 7 rpm to 21 rpm. This speed coupled with the right amount of water is often sufficient to provide a gentle attritioning to wash the deleterious fine material from the particles as well as to convey the material up the 18 degree incline toward the discharge.
Sand screws handle irregular feed particularly well. You can feed a properly sized screw 30 tons per hour or 400 tons per hour and the screw will keep running like nothing has changed. Cyclones are much more sensitive to overfeed situations.
Cyclones are also particularly sensitive to oversize. If an oversize particle enters a cyclone, it only has two ways out through the overflow or the apex, and both of those are small openings. Oversize material can plug the cyclone and halt production.
If an oversize particle enters a sand screw, the screw will simply push it out. EIW Fine Material Washers in particular have a small gap (about 1) between the wear shoes and the close clearance plate running up the length of the incline. If a 1 or 1.5 particle enters with the feed, youll hear it as its going up the screw until it discharges with the rest of the material.
Oversize material in a sand screw wont stop production, but that doesnt mean you can skip screening ahead of the screw. Feeding a screw too much oversize material can lead to premature wear and damage of various screw components.
Sand screws naturally produce a partially dewatered product, as excess water has time to flow away from the washed sand as it is conveyed up the inclined screw. While they produce a conveyable product that can be discharged to an inclined stacking conveyor, at around 20% moisture, the material still needs time for water remaining in the sand to leach out from a stockpile before it can be sold as product.
Sand screws and cyclones are both proven pieces of sand washing equipment, but that is about where the similarities end. Choosing which one is best for your application requires an understanding of your goals and the limitations of the equipment.
Sometimes, however, a combination of a sand screw and cyclone working together is the best option. For example, if you have a high concentration of silt in your feed and a screw alone cant make the required split, adding a cyclone ahead of the screw can help remove those slimes.
Eagle Iron Works or one of its experienced dealers can look at your application and help you to determine whether a screw, cyclone or combination of either in series or both in series is best for your production goals.
EIW, LLC has been providing aggregate beneficiation equipment of exceptional quality for over 140 years. EIW begins by engineering equipment for the defined needs of each customer. We provide support from point of sale throughout the life of the machine, including readily available replacement parts.
MAITEK also supplies a wide range of equipment for the aggregates washing and the sand recovery. Our range of machines includes: sand recovery units with hydro-cyclones, buckets sand recoverers, drum and log washers, dryer screens and rotating washing screens.
The sand recovery units with hydro-cyclones and the buckets sand recoverers have the function to receive the mixture of sand and water with the aim to separate them in order to obtain dry sand and recycle the water that can be reused in the process. The sand recovery units with hydro-cyclones, compared to the buckets sand recoverers, assure better washing performances. The drum and log washer are machines used only for the aggregates washing; the drum washer is better to treat very dirty material while the log washer is better for very hard materials.
The DSP Compact Cyclone Sandwasher range is used to wash sand, recover maximum fines, and dewater sand in a modular self- contained unit. One to two grades can be produced, which are treated to meet standards such as grain size, cleanliness and consistency. This maximises saleable product and produces higher quality outputs. The range is easy to operate and proves both energy and cost efficient for sand production..
McLanahan Sand Washing Plants process sand from its raw state into products that meet various specifications. The process requirements vary depending on the input and desired output, but plants typically scrub, liberate, deslime, wash, classify, decontaminate and dewater the sand, as well as process the effluent stream that results.
For customers who are interested in maximizing yield and producing precisely graded products to the end-user's needs and specifications, it is more likely that a custom sand plant is the correct solution. Whether the sands are natural or manufactured, fine or coarse, well or poorly graded, or required for specialty applications, McLanahan can offer a plant specifically designed to suit your needs.
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.
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; specialty sands and materials such as anti-skid, roofing granules; deligniting/organics removal; and soils washing for environmental projects.
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, McLanahans experienced personnel will guide you through to the best options.
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.
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.
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.
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.
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.
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.
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.
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.
We recently caught up with Willem du Plooy, business development manager from the CDE team in South Africa to discuss the benefits of considering cyclone technology compared to traditional bucket wheel systems for South Africanconstruction and materials processing companies.
Although bucket wheels have been essential to the quarrying industry over the years, increasing demand for sand and aggregates products, as well as increasingly stringent regulatory requirements, mean that operators must produce a wider range of materials in larger quantities and in less time to protect their return on investment and to turn a profit.
Here at CDE, we have developed an alternative solution for construction and materials companies, in the form of cyclone-based systems which, according to du Plooy, guarantee a strong competitive edge and fast return on investment.
He says bucket wheels accept material either directly from the aggregates screening operation, or are fed from classification tanks in applications where there is excess fine material in the -75/-63 micron range, which must be removed.
The operation of the screw pushes the sand fraction up the elevated chamber while the water and finer particles pass through the overflow weir. The overflow weir, which is closer to the feed point, then provides the mechanism for fines removal.
In bucket wheel classifiers, sand slurry is introduced near the wheel, where the coarse sand settles and is lifted by the rotating wheel. The rotary bucket elevator scoops the sand from the tub and drains the water from the sand during transfer. The wastewater flows over weir at the back of the bucket wheel and the solid fraction is separated in the wastewater slurry.
The limited capacity at the feed point of these technologies means that control over the volumes of water required for accurate material classification is difficult, says Du Plooy. The inability to use sufficient volumes of water means that fines are not efficiently removed and 100 300 micron fractions are lost to ponds or to the water treatment phase, along with the overflow, making the sand product coarser.
Diverting excess material to settling ponds requires considerably more space to accommodate them, and the classification inefficiencies increase as the proportion of fines in the feed material increases.
Clearing out settling ponds to recover lost material requires plant downtime in addition to the operating costs incurred when reprocessing waste material. High maintenance and restricted throughput aside, the sand product typically discharged contains between 23% and 25% moisture, placing stockpiles at risk of contamination if located in proximity to one another.
As a consequence, stockpiling the final product requires double or even triple handling to move the material to separate stockpile areas. Stockpiles take long to build and to dry to saleable standards, and return on investment becomes a significant issue, says Du Plooy.
He says cyclone technology is now replacing bucket wheel technology as a natural evolution of materials processing brought about by modern innovations. CDE has developed cyclonic materials technology to the point where it guarantees the removal of the undesired fraction (e.g. -74 micron) while retaining quality fines and maximising dewatering of the product to between 10% and 15% moisture.
Cyclone technology involves the use of centrifugal force as opposed to gravity to classifying materials, says Du Plooy. After testing to determine the proportion of silt material to be removed from the raw feed, the specification of a cyclone set-up is calculated to ensure that the clients EvoWash hydrocyclone-based system provides control over silt cut points.
The design of the cyclone unit allows for an increased number of parameters which, says Du Plooy, ensures improved accuracy on the material cut point. The silt exits the overflow at the top of the cyclone with the wastewater, to be sent to settling ponds or a water recycling system. The sand fraction exits the cyclone at the bottom, ready for dewatering and stockpiling.
Product yield is maximised and operational costs reduced, says Du Plooy. The production of sand and aggregates is guaranteed to be within specifications, in line with the requirements of the customer or their downstream processes.
For instance, a 70 tph machine typically loses 20% sand to the pond which equates to 14 tph of sand lost, resulting in 140 t/day and 3500 t/month. If sand is worth R100 per tonne, that is a loss of R350 000 per month. With the lost sand recovered from the silt pond, a CDE EvoWash could pay for itself anywhere between 6 to 12 months.
The solution to bucket wheels limited ability to dewater sand products effectively lies in using ahigh-frequency dewatering screento dewater the material in one pass, so removing the need for re-processing and double handling, says Du Plooy.
This allows for a sand product with a moisture content typically ranging from 10% to 15%, says Du Plooy. As a result, the product is ready for market straight from the belt, and the sand is turned into revenue in the shortest possible time.
For instance, if sand is worth R100 per tonne, a 70 tph machine loses R7000 for each hour it is out of action due to maintenance or repairs. Our products are designed specifically to require minimum attention, minimal civils and a minimal number of operators so that they can be left to simply produce clean sand and aggregates at the required rate.
Once the feed material has been washed and classified, waste is sent to the AquaCycle thickener tank, where a small amount of polyelectrolyte flocculent is added to the water via an automatic dosing station forcing fine particles to settle to the bottom of the thickener tank.
The clean water at the top overflows the weir and is stored in the AquaStore tank before being re-circulated, says Du Plooy. The result is an efficient water recycling system which requires only a 10% top-up water supply.
He says waste sludge is discharged into a buffer tank where a motorised rake in constant rotation ensures the material does not settle and solidify. If further dewatering is required, a filter press or decanter is added to the wet processing solution to eliminate the need for settling ponds.
He adds all CDE equipment is pre-wired and pre-tested before despatch, to allow for plug-and-play operation, and is designed for rapid assembly and set-up to start processing material within days of arrival on site.
These design considerations and factory acceptance tests reduce install time significantly and accelerate return on investment, a real proposition when the CDE AquaCycle thickener is introduced to a washing operation. In fact, RoI with a CDE AquaCycle is typically achieved within six to nine months.
The requirement for settling ponds is greatly reduced by recycling up to 90% of the process water. The addition of a filter press tailings management system eliminates that need entirely. When combined with a CDE filter press custom-built fines management system, this figure increases to 95%, removing the need for settling ponds altogether.
South African sand and aggregates producer Ground Breakers required an upgrade of the existing bucket wheel system to address the loss of valuable materials to ponds and excess moisture in the final products.
The companys JC Janse van Vuuren and Johan Meintjes explain: Our quarry site in Lanseria faced a lot of challenges: we had limited water sources and space to install a proper wash plant. Silt dams are no solution as they take up valuable mining space.
The market required clean washed concrete sand but the companys bucket wheel was not delivering a quality product. In addition, fines were being lost to settling ponds, wasting material that could not be sold without dredging the ponds and re-processing it through the bucket wheel.
The sand product typically discharged from the Ground Breakers bucket wheel system contained between 23% and 25% moisture, which meant that stockpiling the final product required double or triple handling to move the material to a separate stockpile area.
Ground Breakers feed material was tested at CDE Globals laboratory. The resulting analysis results showed that the customer could achieve savings by adopting cyclone technology to eliminate the loss of fines to ponds.
Incorporated water management would ensure that the final products were dewatered to an average 12% moisture content, making them ready for market straight from the belts. As an added benefit, the fully integrated CDE AquaCycle thickener would allow for up to 90% of the process water to be recycled directly into the system for near-independence from fresh water supplies.
Once the sand slurry with the silt material is discharged from the hydrocyclones, it is delivered to the screen which is sized according to the customers capacity requirements. This allows for the production of a sand product with a moisture content typically ranging from 10% to 15%.
Janse van Vuuren and Meintjes agree: Our CDE Combo is compact and highly efficient. It produces two properly washed products and our customers are happy that the moisture content is so low. This means a considerable cost saving to them, as we generally sell per tonne.
The Combo on the Ground Breakers site, says Du Plooy in conclusion, has allowed the company to maximise yield and reduce its operational costs. The production of sand and aggregates is guaranteed to be within specifications, with no risk of cross-contamination when two products are processed simultaneously.
Switching from a bucket wheel system to the Combo has been conducive to considerable cost savings, as generally, we sell per tonne. The additional -2mm product has many uses, from plastering exterior walls to making paving bricks. It has increased our profitability considerably.JC Janse van Vuuren and Johan Meintjes, Ground Breakers
The cyclone technology is adopted on our multi-functional sand washing machine to recycle fines on the basis of common sand washing machine, and achieves the effect of multi-purpose machine. The role of cyclone in sand washing system is mainly grading, concentration and deliming. Sand and water mixture is pumped to cyclone, which separates sand and water perfectly. Then water is discharged, and sand is dehydrated by dewatering sieve. This achieves reasonable gradation of finished sand , and greatly improves the quality of finished product.
The principle of cyclone is simple centrifugal sedimentation. When separate muddy water and fines, a strong turbulent motion is generated between each other from the periphery to inside of cyclone. Then the generated particles between each particle caused difference centrifugal force of each particle. And finally the sedimentation occurs, coarse and fine particles reach the purpose of classification.
3. Tube for feeding slurry. Sand water mixture to be separated enters cyclone. In order to improve the motion state in cyclone, the separation effect is improved. The structure of cyclone feed tube has many forms.
Mainly refers to the classification of particle size between 3-0.074mm. At this point, suitable diameter and angle of cyclone should be used. Due to the smaller height of cyclone, the centrifugal force is lower and coarser particles can enter the overflow.
Its aim to obtain pure sand, with as little impurities as possible. Large diameter, short tube, and large vertex angle cyclones should be used, and work under low concentration and low pressure conditions. This can achieve a full mixing and rinsing effect.
The purpose is to remove mud from sand. At this moment, a long cylinder and a small cone angle cyclone should be used. And work at low concentrations to separate fine particles at lower centripetal flow rates.
The purpose is to obtain high concentration of sand for next step. Using large diameter, large vertex angle water cyclone, and properly reduce the sedimentation and work under high concentration conditions.
LZZG sand washing plants are the perfect solution for washing artificial sand & aggregates. The wash plant is composed of a spiral sand washing machine, a dewatering screen, a hydro-cyclone group, sludge thickening tank, filter press. The equipment can recover a large number of fines sand lost by the sand washing machine, improve the economic benefit, reduce the disposal cost of the tail water and the pollution and damage caused by the loss of fine sand.
the sieve under the specification enters the cleaning water tank of the sand washing and recycling machine, the sand washing wheel rotates, the material in the cleaning tank is stirred, the cleaning operation is performed, the impurities covering the surface of the material can be removed, and the impurities are cleaned after cleaning. The granular material is sent to the dewatering screen for dewatering by the sand.
the overflow of the integrated machine enters the tail water collecting tank through the pipeline, the tailwater is driven into the separator by the slurry pump, and the sediment is separated by the separator. After the recovery, the fine material is discharged to the dewatering sieve surface and the coarse material is evenly distributed. Discharge after mixing and dehydration. The discharge port is connected to the belt conveyor to transport the finished material to the designated position.
At the same time, the sediment suspended by the separator, the content of which is not more than 5%, is discharged into the sewage pool, and then the tail water is pumped from the sewage pool into the flocculation tank to carry out the mud-water separation operation. The flocculation tank treats about 80% of the tail water into clean water, and then directly enters the clear water pool through the overflow port.
The concentrated mud passes through the bottom of the flocculation tank and is pumped into the plate and frame filter press. The filter press presses the concentrated mud into a mud cake to realize dry heap, landfill or other uses. After the filter press, the clean water enters the clear water tank to realize the recycling of clean water and zero discharge of the entire process.
The hydrocyclone is a high-efficiency grading and desliming device. It has a simple structure and a large processing capacity and is widely used in the sand washing process. The LZZG hydrocyclone uses a wear-resistant alloy material to make the discharge port and the feed material. The wear parts of the mouth effectively solve the wear problem.In the traditional artificial sand wet processing process, when the artificial sand is washed and dewatered by a spiral sand washing machine or a wheel sand washing machine, the loss of fine sand in the artificial sand can hardly be controlled. The fines sand recovery system can effectively reduce the loss of fine sand and control it within 5%-10%, which is a good solution to the high fineness modulus of the finished sand in the artificial aggregate processing system. The problem of low stone powder content increases customer profitability.
Prevent fine sand and sludge from entering the sedimentation tank, prevent siltation of the sedimentation tank, help to protect the environment, and greatly reduce the cost of cleaning the sedimentation tank;
The sand washing equipment suit for ore, sand, slime coal, frac sand washing and dewatering. Sand washing equipment is widely used in construction, sand and gravel plants, hydropower station concrete dam construction sites and other industries. It has high washing degree, reasonable structure, large processing capacity, low power consumption, and less sand loss during sand washing machine. In particular, the transmission part of the sand washing machine is isolated from water and sand, so the failure rate is much lower than that of common sand washing equipment.
Model feed size (mm) Spiral diameter (mm) Sink length (mm) sieve size (mm) Separator Specifications Processing water volume (m3/h) Sand output (t/h) Standard total power (Kw) weight (kg) Dimensions (mm) with pump and motor LX09-65-1530J 10 920 8000 1500*3000 FX300*2 120-180 50-80 47 8480 11490*5560*3960 LX09-75-1836D 10 920 8000 1800*3600 FX350*2 160-200 60-100 56 10140 11920*5560*4080 2LX09-100-2442J 10 920 8000 2400*4200 FX250*4 200-280 150-180 81 16950 12630*6450*3860 2LX09-100-2448J 10 920 8000 2400*4800 FX250*4 200-280 150-180 81 17250 14660*6450*4150 LX11-75-1836D 10 1120 8500 1800*3600 FX350*2 160-240 100-150 63.5 11440 12230*5860*4250 LX11-75-1836J 10 1120 8500 1800*3600 FX350*2 160-240 100-150 70.5 11750 12230*5860*4250 LX11-75-1842D 10 1120 8500 1800*4200 FX350*2 160-240 100-150 63.5 12300 12830*5860*4250 LX11-100-1842J 10 1120 8500 1800*4200 FX250*4 200-280 100-150 77.5 12550 12830*5860*4250 LX11-100-1848J 10 1120 8500 1800*4800 FX250*4 200-280 100-150 77.5 12550 12830*5860*4250 2LX11-120-3048J 10 1120 8500 3000*4800 FX300*4 240-360 200-250 120 27520 13560*7860*4300