Silica sand low in iron is much in demand for glass, ceramic and pottery use, and for many of these applications clean, white sand is desired. Impurities such as clay slime, iron stain, and heavy minerals including iron oxides, garnet, chromite, zircon, and other accessory minerals must not be present. Chromium, for example, must not be present, even in extremely small amounts, in order for the sand to be acceptable to certain markets. Feldspars and mica are also objectionable. Generally, iron content must be reduced to 0.030% Fe2O3 or less.
Silica sand for making glass, pottery and ceramics must meet rigid specifications and generally standard washing schemes are inadequate for meeting these requirements. Sand for the glass industry must contain not more than 0.03% Fe2O3. Concentrating tables will remove free iron particles but iron stained and middling particles escape gravity methods. Flotation has been very successfully applied in the industry for making very low iron glass sand suitable even for optical requirements.Sub-A Flotation Machines are extensively used in this industry for they give the selectivity desired and are constructed to withstand the corrosive pulp conditions normally encountered (acid circuits) and also the abrasive action of the coarse, granular, slime free washed sand.
The flowsheet illustrates the more common methods of sand beneficiation. Silica may be obtained from sandstone, dry sand deposits and wet sand deposits. Special materials handling methods are applicable in each case.
The silica bearing sandstone must be mined or quarried much in the manner for handling hard rock. The mined ore is reduced by a Jaw Crusher to about 1 size for the average small tonnage operation. For larger scale operations two-stage crushing is advisable.
The crushed ore is reduced to natural sand grain size by Rod Milling. Generally, one pass treatment through the Rod Mill is sufficient. Grinding is done wet at dilutions in excess of normal grinding practice. A Spiral Screen fitted to the mill discharge removes the plus 20 mesh oversize which either goes to waste or is conveyed back to the mill feed for retreatment.
Sand from such deposits is generally loaded into trucks and transported dry to the mill receiving bin. It is then fed on to a vibrating screen with sufficient water to wash the sand through the 20 mesh stainless screen cloth. Water sprays further wash the oversize which goes to waste or for other use. The minus 20 mesh is the product going to further treatment.
The sand and water slurry for one of the three fore-mentioned methods is classified or dewatered. This may be conveniently done by cyclones or by mechanical dewatering classifiers such as the drag, screw, or rake classifiers.
From classification the sand, at 70 to 75% solids, is introduced into a Attrition Scrubber for removal of surface stain from the sand grains. This is done by actual rubbing of the wet sand grains, one against another, in an intensely agitated high density pulp. Most of the work is done among the sand grains not against the rotating propellers.
For this service rubber covered turbine type propellers of special design and pitch are used. Peripheral speed is relatively low, but it is necessary to introduce sufficient power to keep the entire mass in violent movement without any lost motion or splash. The degree of surface filming and iron oxide stain will determine the retention time required in the Scrubber.
The scrubbed sand from the Attrition Machine is diluted with water to 25-30% solids and pumped to a second set of cyclones for further desliming and removal of slimes released in the scrubber. In some cases the sand at this point is down to the required iron oxide specifications by scrubbing only. In this case, the cyclone or classifier sand product becomes final product.
Deslimed sand containing mica, feldspar, and iron bearing heavy minerals can be successfully cleaned to specifications by Sub-A Flotation. Generally this is done in an acid pulp circuit. Conditioning with H2SO4 and iron promoting reagents is most effective at high density, 70-75% solids. To minimize conditioning and assure proper reagentizing a two-stage Heavy Duty Open Conditioner with Rubber Covered Turbine Propellers is used. This unit has two tanks and mechanisms driven from one motor.
The conditioned pulp is diluted with water to 25-30% solids and fed to a Sub-A Flotation Machine especially designed for handling the abrasive, slime free sand. Acid proof construction in most cases is necessary as the pulps may be corrosive from the presence of sulfuric acid. A pH of 2.5-3.0 is common. Wood construction with molded rubber and 304 or 316 stainless steel are the usual materials of construction. In the flotation step the impurity minerals are floated off in a froth product which is diverted to waste. The clean, contaminent-free silica sand discharges from the end of the machine.
The flotation tailing product at 25 to 30% solids contains the clean silica sand. A SRL Pump delivers it to a Dewatering Classifier for final dewatering. A mechanical classifier is generally preferable for this step as the sand can be dewatered down to 15 to 20% moisture content for belt conveying to stock pile or drainage bins. In some cases the sand is pumped directly to drainage bins but in such cases it would be preferable to place a cyclone in the circuit to eliminate the bulk of the water. Sand filters of top feed or horizontal pan design may also be used for more complete water removal on a continuous basis.
Dry grinding to minus 100 or minus 200 mesh is done in Mills with silica or ceramic lining and using flint pebbles or high density ceramic or porcelain balls. This avoids any iron contamination from the grinding media.
In some cases it may be necessary to place high intensity magnetic separators in the circuit ahead of the grinding mill to remove last traces of iron which may escape removal in the wet treatment scrubbing and flotation steps. Iron scale and foreign iron particles are also removed by the magnetic separator.
In general most silica sands can be beneficiated to acceptable specifications by the flowsheet illustrated. Reagent cost for flotation is low, being in the order of 5 to 10 cents per ton of sand treated. If feldspars and mica must also be removed, reagent costs may approach a maximum of 50 cents per ton.
Laboratory test work is advisable to determine the exact treatment steps necessary. Often, attrition scrubbing and desliming will produce very low iron silica sand suitable for the glass trade. Complete batch and pilot plant test facilities are available to test your sand and determine the exact size of equipment required and the most economical reagent combinations.
Silica sand for making glass, pottery and ceramics must meet rigid specifications and generally standard washing schemes are inadequate for meeting these requirements. Sand for the glass industry must contain not more than 0.03% Fe2O3. Concentrating tables will remove free iron particles but iron stained and middling particles escape gravity methods. Flotation has been very successfully applied in the industry for making very low iron glass sand suitable even for optical requirements.
Sub-A Flotation Machines are extensively used in this industry for they give the selectivity desired and are constructed to withstand the corrosive pulp conditions normally encountered (acid circuits) and also the abrasive action of the coarse, granular, slime free washed sand.
The flowsheet illustrated is typical for production of glasssand by flotation. Generally large tonnages are treated, forexample, 30 to 60 tons per hour. Most sand deposits can be handled by means of a dredge and the sand pumped to the treatment plant. Sandstone deposits are also being treated and may require elaborate mining methods, aerial tramways, crushers, and wet grinding. Rod Mills with grate discharges serve for wet grinding to reduce the crushed sandstone to the particle size before the sand grains were cementedtogether in the deposit. Rod milling is replacing the older conventional grinding systems such as edge runner wet mills or Chilean type mills.
Silica sand pumped from the pit is passed over a screen, either stationary, revolving or vibrating type, to remove tramp oversize. The screen undersize is washed and dewatered generally in a spiral type classifier. Sometimes cone, centrifugal and rake type classifiers may also be used for this service. To clean the sand grains it may be necessary to thoroughly scrub the sand in a heavy-duty sand scrubber similar to the Heavy-duty Agitator used for foundry sand scrubbing. This unit is placed ahead of the washing and dewatering step when required. The overflow from the classifier containing the excess water and slimes is considered a waste product. Thickening of the wastes for water reclamation and tailings disposal in some areas may be necessary.
The washed and dewatered sand from the spiral-type classifier is conveyed to a storage bin ahead of the flotation section. It is very important to provide a steady feed to flotation as dilution, reagents and time control determines the efficiency of the process.
Feeding wet sand out of a storage bin at a uniform rate presents a materials handling problem. In some cases the sand can be uniformly fed by means of a belt or vibrating-type feeder. Vibrators on the storage bin may also be necessary to insure uniform movement of the sand to the feeder. In some cases the wet sand is removed from the bin by hydraulic means and pumped to a spiral-type classifier for further dewatering before being conveyed to the next step in the flowsheet.
Conditioning of the sand with reagents is the most critical step in the process. Generally, for greater efficiency, it is necessary to condition at maximum density. It is for this reason the sand must be delivered to the agitators or conditioners with a minimum amount of moisture. High density conditioning at 70 to 75% solids is usually necessary for efficient reagentizing of the impurity minerals so they will float readily when introduced into the flotation machine.
The Heavy-duty Duplex Open-type Conditioner previously developed for phosphate, feldspar, ilmenite, and other non-metallic mineral flotation is ideal for this application. A duplex unit is necessary to provide the proper contact time. Circular wood tanks are used to withstand the acid pulp conditions and the conditioner shafts and propellers are rubber covered for both the abrasive and corrosive action of the sand and reagents.
Reagents are added to the conditioners, part to the first and the balance to the second tank of the duplex unit, generally for flotation of impurities from silica sand. These reagents are fuel oil, sulphuric acid, pine oil, and a petroleum sulfonate. This is on the basis that the impurities are primarily oxides. If iron is present in sulphide form, then a xanthate reagent is necessary to properly activate and float it. The pulp is usually regulated with sulfuric acid to give a pH of 2.5-3.0 for best results through flotation.
A low reagent cost is necessary because of the low value of the clean sand product. It is also necessary to select a combination of reagents which will float a minimum amount of sand in the impurity product. It is desirable to keep the weight recovery in the clean sand product over 95%. Fatty acid reagents and some of the amines have a tendency to float too much of the sand along with the impurities and are therefore usually avoided.
After proper reagentizing at 70 to 75% solids the pulp is diluted to 25 to 30% solids and introduced into the flotation machine for removal of impurities in the froth product. Thepulp is acid, pH 2 .5 to 3.0 and the sand, being granular and slime free, is rapid settling so a definite handling problem is encountered through flotation.
The Sub-A Flotation Machine has been very successful for silica sand flotation because it will efficiently handle the fast settling sand and move it along from cell to cell positively. Aeration, agitation and selectivity due to the quiet upper zone can be carefully regulated to produce the desired separation. The machine is constructed with a wood tank and molded rubber wearing parts to withstand the corrosive action of the acid pulp. Molded rubber conical-type impellers are preferred for this service when handling a coarse, granular, abrasive sand.
Flotation contact time for removal of impurities is usually short. A 4, and preferably a 6 cell, machine is advisable. Cell to cell pulp level control is also desirable. A 6 cell No. 24 (43 x 43) Sub-A Flotation Machine in most cases is adequate for handling 25 to 30 tons of sand per hour. If the impurities are in sulphide form a standard machine with steel tank and molded rubber parts is adequate provided the pulp is not acid. Otherwise acid proof construction is essential.
The flotation tailing product is the clean sand discharging from the end of the flotation machine at 25 to 30% solids and must be dewatered before further processing. Dewatering can be accomplished in a dewatering classifier and then sent to storage or drying. Top feed or horizontal vacuum filters are often used to remove moisture ahead of the dryer. Dry grinding of the sand to meet market requirements for ceramic and pottery use is also a part of the flowsheet in certain cases.
This particular sand was all minus 20 mesh with only a trace minus 200 mesh and 70% plus 65 mesh. Iron impurity was present as oxide and stained silica grains. The plant which was installed as a result of this test work is consistently making over a 95% weight recovery and a product with not over 0.02% Fe2O3 which at times goes as low as 0.01% Fe2O3.
Si02, minimum..99.8 per cent Al2O3, maximum..0.1 percent Fe2O3, maximum..0.02 per cent CaO + MgO, maximum.0.1 percent For certain markets, a maximum of 0.030 per cent Fe2O3 is acceptable.
Natural silica-sand deposits generally contain impurityminerals such as clay, mica, and iron oxide and heavy iron minerals which are not sufficiently removed by washing and gravity concentration. Flotation is often used to remove these impurity minerals to meet market specifications.
Anionic-type reagents, such as fatty acids, are used to float some impurities in alkaline pulp. Cationic-type reagents such as amines or amine acetates are also used with inhibitors such as sulphuric or hydrofluoric acids to float certain impurity minerals and depress the silica.
Materials engineers constantly strive to improve concrete and bituminous mixes and road bases, and clean aggregate is a vital part of that effort. Yet, aggregate producers often find it difficult to meet all the requirements for cleanliness. While hydraulic methods are most satisfactory for cleaning aggregate to achieve desired results, they are not always perfect. It is still necessary to accept materials on the basis of some allowable percent of deleterious matter.
In broadest terms, construction aggregate is washed to make it meet specifications. Specifically, however, there is more to the function of water in processing aggregate than mere washing. Among these functions are:
Because no washing method is flawless, and because some materials may require too much time, equipment and water to make them conform to specifications, it is not always economically practical to use such materials.
Further, many manufacturers of washing equipment will examine and test samples to determine whether their equipment can do the job satisfactorily. No reputable equipment manufacturer wants to recommend equipment if it has reasonable doubt about satisfactory performance on the job.
The ideal gradation is seldom, if ever, met in naturally occurring deposits. Yet, the quality and control of these gradations is absolutely essential to the workability and durability of the end use. Gradation, however, is a characteristic that can be changed or improved with simple processes, and is the usual objective of aggregate-preparation plants.
With specifications becoming increasingly stringent, washing and classifying of aggregate materials is ever increasing. As pits and quarries progress into their reserves, the more easily extracted material is less available, often forcing operations particularly sand and gravel operations to process material with a greater amount of clay and silt. While some materials may require only rinsing to remove small silt particles, other materials may require scrubbing to remove clay and other deleterious materials.
Sand and gravel typically are mined in a moist or wet condition by open pit excavation or by dredging. Open pit excavation is often conducted with power shovels, front-end loaders, bucket-wheel excavators or draglines. Alternatively, dredging involves mounting equipment on boats or barges and removing the sand and gravel from the bottom of a body of water by suction or bucket-type dredges. After mining, the materials are transported to the processing plant by suction pump, earthmovers or trucks, or by the method of automated belt conveyor systems.
Processing sand and gravel products for a variety of specific market applications requires the use of different combinations of equipment, which may include portable and stationary washing and screening plants; sand classification tanks and systems; dewatering screens and screws; coarse and fine material washers; blade mill washers; log washers; rotary and vibrating screens; and more.
Manufactured sand is produced from the crushing of hard stone such as granite. As an alternative to river sand, the use of manufactured sand is becoming more prevalent because of dwindling natural sand reserves or the constraints and expense of extracting natural sand and gravel near urban areas where material is most needed.
Washing and classifying also may be used in processing manufactured sand. The crushing process creates a significant amount of fines, which are undersized fine particles that pass through the smallest screen openings (which are measured by mesh sizes). The minus-#100 and minus-#200 mesh fines require washing to be removed. While these fines are allowable in the bottom-end of asphalt sand products, it is common to wash manufactured sand in this application. Most concrete sand products require the removal of fines. Equipment choices vary in the removal of fines from the use of a wet screen to the use of a classifying system.
Manufactured sand is widely accepted in asphalt mixes. In concrete mixes, manufactured sand is often blended with natural sand. Washing (versus air separation) is recommended when classifying material for concrete mixes. When blending natural and manufactured sand, it is best to use a classifying tank.
The initial material feed that passes through the coarsest screen (largest screen openings) is washed in a log washer before it is further screened. The name log washer comes from the early practice of putting short lengths of wood logs inside a rotating drum filled with sand and gravel to add to the scrubbing action. A modern log washer consists of a slightly inclined horizontal trough with slowly rotating blades attached to a shaft that runs down the axis of the trough. The blades churn through the material as it passes through the trough to strip away any remaining clay or soft soil. The larger gravel particles are separated out and screened into different sizes, while any smaller sand particles that had been attached to the gravel may be carried back and added to the flow of incoming material.
The water and material that pass through the finest screen are pumped into a horizontal sand classifying tank. As the mixture flows from one end of the tank to the other, the sand sinks to the bottom where it is trapped in a series of bins. The larger, heavier sand particles drop out first, followed by the progressively smaller sand particles, while the lighter silt particles are carried off in the flow of water. The water and silt are then pumped out of the classifying tank and through a clarifier where the silt settles to the bottom and is removed. The clear water is recirculated to the feeder to be used again.
It is important to take a closer look at sand classification systems. Sand classifying and re-blending systems allow material producers to modify a raw natural sand blend into a high-quality, industry-standard specification mix; or blend a natural sand and a manufactured sand to a desired specification product mix. Classifying systems are available in either stationary, portable or semi-portable configurations. The choice of a particular configuration depends on the physical characteristics of the sand mining site and any relocation needs.
Classifying and re-blending systems allow producers to do the following: Scalp (remove) excess water from dredged material. Reject deleterious (harmful) material. Separate sand particles. Re-blend sand particles to create more than one spec product simultaneously.
Sand classification systems use water and the principles of gravity and settling to separate and re-blend sand. For a traditional classifying tank, the industry-standard method is based on the principle that coarser sand particles are heavier and will settle near the feed end. Finer and lighter sand particles are carried progressively further down the length of the tank. During this process, the tank is constantly supplied with a feed of water that keeps the top of the tank overflowing. This constant movement of water over the edge of the tank (or weir) helps eliminate organics and other material that should not be present in the final sand blend.
As the sand particles of different sizes settle to the bottom of the tank, they begin to pile up around valves located there. These valves are typically installed in sets of two or three. Valves are grouped together in stations, and each station is equipped with a sensing paddle that turns at a slow but constant speed. As the sensing paddle turns, the sand builds up around it. Once enough sand piles up around the paddle, the paddle begins to stall, sending a signal to the classifying tank controller that this stations area is filling up with sand. In turn, this signal causes the valve or valves in that station to open up to discharge sand.
The sand that is discharged from each station is sent into a flume at the bottom of the tank where the sand is remixed and dumped into one of several dewatering devices. Once the sand has been separated from the water, it is moved with conveyors to large stockpiles. Sand is stored in these stockpiles to dry and then shipped to customers for use in a wide variety of projects, including concrete mixes, masonry mixes, golf course bases, and sand traps and fill sand.
Each of these re-blended products is made of a different mixture or recipe specification of particle sizes. Specifications are created in a variety of ways, but all are measured by the amount of material that either passes through or is retained by different-sized sieves or screens. Within these specifications, the producer must determine sieve sizes, along with just how much material must be of a specified size. To remain competitive and profitable, operations typically rely upon skilled quality control teams to test, monitor and maintain all specification requirements of final products.
Most classifying plants are operated via automated control systems. To meet finished product specifications, the feed rate of incoming material, the vibration rate of the sorting screens, and the flow rate of the water through the sand classifying tank must be carefully monitored and controlled. Automated control systems allow the operator to compensate easily for changes in the feed or slurry mix being fed to the plant, to closely monitor the manufacture of sand products for total tonnage and quality and to automatically make products to a closely defined, predetermined specification with few (if any) operator calculations, minimizing the opportunity for human error.
In the processing and handling of sand, gravel or crushed stone, it is necessary to complete the separation or dewatering of the fine solid materials from the slurry containing them. With that in mind, new solutions to the problem are often developed, such as recently introduced unit that is a combination of a fine material washer and a dewatering screen.
Washing sand and aggregate results in the discharge of dirty water from wet screening decks, sand screws or sand classifiers. The wastewater typically carries fines out to a series of settling ponds. While this is the most common method of treating wash water fines, it is not the most sustainable method. As such, many operations employ equipment such as filter presses, hydrocyclones, water clarifiers and flocculent systems to more efficiently reclaim and reuse wash water and to minimize settling pond use and maintenance.
Water being recovered for washing may be lost to evaporation or percolation in the pond, which may require the operator to provide make-up water (which may be scarce) to the plant. The real estate for a properly sized settling pond may not exist at the plant site. The cost and time involved in cleaning the ponds with a dragline or excavator may be excessive. And, cleaning a pond especially the fine material that flows downstream and settles very slowly is extremely inefficient. Dirty water may get back to the plant, limiting production, producing washed material out of spec, or even shutting down production. Ponds may present hazards to nearby equipment and to workers.
However, some sites can be ideally suited to the use of settling ponds. Some operations may access an exhausted portion of a large quarry where the dirty water can be deposited and the fines never need to be recovered. Clean water is recovered from the opposite end of the pond and the fines settle down in the deep quarry bottom, never to be dealt with again.
Hydrocyclones are tapered cones that receive the dirty wash water at a high velocity. The water travels in a tight circle within the cone and centrifugal force throws the largest particles to the outside of the cone where they slide down the cone and out the bottom. Rather than discarding all the particles into a settling pond, the cones can recover the #200-mesh and larger material, which can be sold as aglime, mineral filler, lining for utility trenches, mortar, grout additives and more.
Water clarifiers are of value to a producer who wants to minimize settling pond maintenance and reclaim a large percentage of the water immediately. Also, for those producers who have an area that has already been mined and will ultimately be reclaimed, a good clarifier can pump the solids to that area, and it never needs to be conveyed, loaded or hauled again. While clarifiers may require a significant initial capital outlay, they require minimal maintenance and operating costs.
Clarifiers are combined with flocculent systems. Flocculants rapidly settle out virtually all of the suspended solids in a dirty water stream. Liquid flocculants require very little hardware and can be introduced via a small chemical metering pump with some dilution water added. However, liquid flocculants are not always environmentally friendly and often separate or stratify in the container before use. Dry flocculants are more environmentally friendly but require more sophisticated equipment to get them into the solution properly. It is imperative to work with a competent vendor to select the right flocculent for a given application.
Filter presses take the silt that a clarifier has collected and essentially squeeze the water out of it to form a cake that is discharged and can be conveyed or transported by a loader to a disposal area; or the cakes can be used as backfill material. The use of clarifiers and filter presses minimizes fines going into settling ponds, while making waste material easier to handle.
Lastly, it is important to conduct periodic water audits to determine the best and most sustainable use of water within the aggregate washing process. Operations should develop a maintenance program that routinely inspects all plumbing equipment and fixtures, water lines, spray systems, valves and pumps. Metering at strategic points in the facility helps to detect leaks and maintains minimum flow rates. But, above all, operations should employ the optimal reuse and recycling systems for aggregate washing.
Selecting equipment for washing and classifying can seem like a daunting task. There are countless solutions using a variety of equipment that can be put together based on a producers needs. Although some of this equipment was detailed earlier, following is a more-complete overview of wet processing equipment available to aggregate producers.
Aggregate conditioners are designed to help producers start to liberate light, loamy clay or dirt from either coarse rock or sand before further processing. They can be placed ahead of a wash screen or other washing equipment, such as sand classifying tanks or fine material screw washers. Using a combination of paddles and flights arranged in alternating format along the length of the shaft, aggregate conditioners begin to scour, abrade and break down deleterious material.
Although similar in appearance to coarse material screw washers, aggregate conditioners function very differently. For example, all material and water entering the aggregate conditioner must exit through the discharge opening at the bottom of the box opposite the feed end. There is no overflow. They sit on a slope of zero to 5 degrees, which gives them much greater capacities.
Built primarily to wash crushed stone and gravel, coarse material screw washers effectively remove light, loamy clays, dirt, crusher dust and coatings that cannot be removed by wet screening alone. They also can be used to remove floating vegetation and soft aggregate from the material feed.
Coarse material screw washer paddles are used in conjunction with screw flights to provide scouring and agitation. The turbulent washing action combined with rising current water, which is introduced at the feed-end at the bottom of the box, results in separation of the lighter fraction from the sound aggregate.
Lighter fractions float to the surface due to water rising in the box and then overflow the weir located at the back of the box. Desired clean product is then scrubbed and conveyed by the paddles and flights to the discharge end of the box.
Paddle configurations can vary based on the design and length of the coarse material screw washer. More paddles increase washing action but decrease capacity because paddles do not convey material up the washer box as fast as flights. When using additional paddles, it is necessary to lower the slope of the box and increase motor horsepower, which will help convey material to the discharge end. Additionally, reversing some of the paddles will retain material in the box longer.
Fine material screw washers are used primarily to dewater, classify and wash minus-3/8in. sand or other fine material. They are designed to accept feeds from sand classifying tanks, belt conveyors, other fine material screw washers or slurry feeds.
In a fine material screw washer, as material enters the feed box, heavier material sinks to the bottom of the box, while finer fractions float to the surface and over the back weir. Material that sinks is then conveyed from the pool area up an 18-degree slope toward the discharge end.
As material is conveyed, it enters the dry deck section of the washer box at which point the water begins to separate from the material. Curvature of the rotating screw flights conform to the curved section of the washer box to efficiently convey, wash and dewater.
Log washers are used in aggregate processing to remove tough, plastic-type clays from natural and crushed gravel, stone and ore feeds. When in operation, log washers sit at a slope of between zero to 14 degrees, depending on the severity of the washing application. As the percentage of deleterious material increases, the slope must be raised to increase retention time. In some cases, lower slopes are able to increase capacity while decreasing horsepower and wear.
One limitation of log washers is that they must have a controlled top size. In general, 36in.- and 38in.-diameter units can accept feed material up to 4 in., while a 46in.-diameter unit can accept feed material as large as 6 in. cubed. It is recommended that sand-sized fractions be removed prior to the log washer as finer material tends to cushion the washing action.
When selecting a log washer, the amount, type and percentage of deleterious material to be removed from the aggregate must be considered. As the percentage of deleterious material increases, consider longer-length units to increase the washing action. In some severe applications, two or more log washers in a series may be required.
Sand classifying tanks provide several results, including removing excess water, classifying material by removing excess of certain mesh sizes, retaining finer mesh sizes and making multiple products from a single feed material. They are effective, low-maintenance units that produce one or more specific products. With either slurry or a dry feed, they are capable of handling sand gradation swings in the average plant, while minimizing waste.
Sand classification is based on the different settling rates of various grain sizes. As water and aggregate material enter the feed end, coarser grains settle first, and finer grains settle in successive sizes down the length of the tank. At the top of the tank, a series of hydraulic control mechanisms operate the discharge valves at the bottom of the tank. Depending on the type of control system and product produced, one, two or three discharge valves are located at each station.
Attrition scrubbers, also known as attrition cells, are used to liberate deleterious material and remove it from competent aggregate material. They are also proven to liberate clays, reducing product turbidity, and to break apart loosely conglomerated clusters in frac sand plants. Attrition scrubbers also can be used in glass sand, frac sand, clay and sand and gravel production, as well as in preparation of flotation feeds and reagent washing.
Attrition scrubbers produce a high-shear environment where particles scrub against themselves to scour their surface and liberate deleterious materials. All internal parts are completely rubber lined to maximize wear life and minimize maintenance time and costs of replacement parts.
They are designed to produce a consistent drip-free product, which is typically significantly drier than other dewatering equipment, such as fine material screw washers. Materials such as sand, gravel, crushed aggregates, frac sand, industrial sands, mineral sands, etc., are all capable of being processed through a dewatering screen.
To dewater material effectively, slurry is fed onto a steep, downward-inclined screen surface at the feed end of the dewatering screen to achieve rapid drainage. A pool of water begins to form in the valley as material builds up on the slightly upward inclined surface.
Counter rotating motors create a linear motion, driving solids uphill, while liquid drains through the screen media. The uphill slope of the screen, along with a discharge weir, creates a deep bed that acts as a filter medium, allowing retention of material much finer than the screen openings.
Crushed stone, sand and gravel products make up the construction aggregates industry and lay the groundwork for many infrastructure projects that are essential to our way of life. McLanahan designs and manufactures equipment that can be used in all steps of the production of construction aggregates, from crushing the material to the desired size and sorting the various sizes for specific uses, to maximizing fines recovery and eliminating settling ponds.
McLanahan offers a variety of crushing solutions to help aggregate producers better control the size and shape of their product. The company offers a wide range of primary, secondary and tertiary crushers for reducing and refining aggregate material through compression, impact, and attrition or shear forces. McLanahans in-house laboratory offers material testing to provide you with a machine that will fit your crushing requirements.
McLanahan Feeders deliver aggregate material to both the initial and downstream processes by means of moving apron pans, vibration, reciprocating plates or rollers. The Feeders are designed specifically for the applications material size, weight and desired throughput, and then programmed to feed the aggregate at a set rate to match the capacity of a conveyor belt or crusher. Some are designed with the means to scalp the feed to filter out the undersized product.
Screens are used to separate a flow of aggregate material according to its size. This is accomplished by giving the material plenty of opportunities to pass through the screening media and allowing particles that adhere to each other to dislodge in the process. McLanahan offers both stationary and portable screening equipment designed to segregate material, reduce fines generation, remove refuse material and minimize crusher size.
McLanahans extensive line of washing and classifying equipment helps aggregate producers meet specifications by removing excess water and rejecting deleterious material. The companys equipment also allows for sizing, separating and dewatering. Aggregate producers need only tell McLanahans experienced sales and process engineering teams their feed gradation and desired size, and McLanahan will provide them with a complete system model as well as product yield and waste predictions. Because requirements vary from site to site, McLanahans extensive range of equipment ensures that each customer has the best solution for their washing and classifying application and will get the highest ROI from their equipment purchase.
Attrition Cells/Scrubbers I Blade MillsI Dewatering Screens I Flat Bottom Classifiers/Lites-Out I Hydrocylcones I Hydrosizers I Log Washers I Modular Wash Plants I Sand Classifying Tanks ISand Washing Plants I Screw Washers I Slurry Pumps I Thickeners I Ultra Fines Recovery Plants I Vibratory Screens
McLanahan offers one of the largest selections of dewatering equipment in the industry, including Dewatering Screens, Filter Presses, Fine Material Screw Washers, Hydrocyclones and Separators, and Thickeners/Clarifiers, to remove moisture from end products. McLanahan dewatering equipment produces a drier, drip-free end product. It also helps producers create a sustainable environment and helps plants with permitting and regulatory issues by reducing and/or eliminating settling or tailings ponds.
Dewatering Screens I Filter Presses I Hydrocyclones I Hydrosizers I Modular Wash Plants I Sand Washing Plants I Screw Washers I Slurry Pumps I Thickeners I Ultra Fines Recovery Plants I Vibratory Screens
Certain applications in the aggregates industry can require very tight tolerances when it comes to sampling accuracy and precision. McLanahan can provide aggregates producers with a large range of sampling solutions to monitor the quality of their product. McLanahan Mechanical Sampling Systems are designed to extract samples from a moving belt, offering a safer collection method and an accurate way of monitoring product quality.
Mixing/blending is the process of combining various material to create a new, uniform product. When combined, these materials create a new, uniform product. McLanahans line of Pug Mill Mixers/Road Base Mixers are designed for use in many industries and for many applications, including blending road base materials.
McLanahan offers a number of solutions when it comes to fines recovery. This equipment allows aggregate producers to comply with permitting and environmental regulations, reduce pond maintenance costs and extend pond life. In some cases, the need for tailings/settling ponds can be reduced or eliminated, which frees up time and land resources. Aggregate producers who recover fines may also discover a potential saleable product.
Dewatering Screens I Filter Presses I Flat Bottom Classifiers/Lites-Out I Hydrocyclones I Hydrosizers I Screw Washers I Slurry Pumps I Ultra Fines Recovery Plants I Vibratory Screens
Most wet processing facilities have some sort of water management system in place in order to meet environmental regulations. McLanahan offers water management solutions that can help aggregate producers reclaim process water for reuse, as well as reduce or eliminate tailings or settling ponds by getting the solids into a state where they can be easily handled and transported.
Construction aggregates are produced from naturally occurring mineral deposits, including solid rock formations such as limestone and granite, and from loose deposits of sand and gravel. The most common structural uses of construction aggregates include the coarse and fine mineral components in Portland cement concrete and asphalt. Aggregates are used for road base and gravel roadways, as well as produced for use in everyday materials, such as paint, light bulbs and white appliances. Construction aggregates are also produced as byproducts from other manufacturing processes such as steel mill slag.
In the mining business since 1835,McLanahan employs a team of process design experts who are able to help you create a more efficient, more productive and more profitable site. McLanahan ensures your aggregate product conforms to the specific sizes needed to meet demanding specifications, as well as ensures your application is satisfying water usage permits. Let McLanahan's crushing, feeding, screening/sizing, washing and classifying, dewatering, sampling, mixing/blending, fines recovery and tailings management solutions help you produce your desired aggregate material.
Sand, aggregate and minerals must be washed in order to meet many required specifications for various projects. Washing and classifying equipment provides producers with the ability to remove excess water and deleterious materials such as clay, silt, shale, coal, soft stone, roots, twigs and other debris from the rock.
McLanahan manufactures a wide range of washing and classifying equipment, meaning the company is able to select an option that will ensure each customer has the best process engineered solution for their washing and classifying application.
McLanahans washing equipment can help producers meet specifications by removing the deleterious material that can harm final products. This equipment employs rotating paddles and screw shafts to scour and abrade the material, as well as a rising current of water to aid in the liberation of clays, crusher dust, silt and other fine material. The agitation of the equipment results in particle-on-particle attrition that also helps to remove deleterious material.
Classifying equipment from McLanahan can help producers to separate even the smallest material to create products of various mesh sizes. This allows producers to do more with a single deposit, potentially increasing their profitability. Besides classification, McLanahans classifying equipment can also aid in the removal of lightweight deleterious material.
Flat-Bottom Classifiers/Lites-Out I Hydrocyclones I Hydrosizers I Rotary Trommels I Sand Classifying Tanks I Sand Washing Plants I Screw Washers I Slurry Pumps I Thickeners I Ultra Fines Recovery Plants
If not washed, construction material containing deleterious materials can cause cracking in structural projects and prevent drainage in transportation projects. Similarly in the coal industry, unwashed coal can decrease its quality and efficiency and, therefore, its price.
Washing is becoming increasingly important as producers find themselves progressing farther into their reserves and extracting material with greater amounts of deleterious materials, or facing stricter specifications for their construction aggregate. Washing and classifying equipment helps producers meet these strict specifications and do more with their deposit.
Another function of washing and classifying equipment is particle sizing. Classifying equipment is ideal for separating material that is too small to be sized on traditional screening equipment. Using classifying equipment, producers can remove excess material, retain finer particles and create multiple products from a single feed. In this way, producers are able to make the most of their deposit by creating additional salable products at one time.
There are many options when it comes to choosing the right washing and classifying equipment for your application. Some material only requires rinsing on a screen to remove the undesirables, while other material requires a more vigorous washing process to liberate the clay and other debris.Certain equipment is best for washing coarse materials, while other equipment is ideal for washing and classifying fine materials. In order to process material for a variety of markets, producers can employ a combination of washing and classifying equipment to meet their needs.
ZENITH's stone crushers are designed to achieve larger productivity and higher crushing ratio. We have jaw crushers, impact crushers, cone crushers, sand makers and so on. They can meet various production needs through free combinations.
ZENITHs new generation of portable crushing plants contain 7 series and 72 models, which can satisfy all kinds of production needs by free combination. Besides, the mobile crushing plants are also popular among markets. Both portable and mobile crushing plants are highly flexible. They can work on various terrible terrains and help customers get returns on investments quickly.
MS series steel platform guided by global high standard design idea, adopts the standard modular design concept, with fast delivery cycle, convenient transportation and installation, which can meet the requirements of the current construction and use of crushing and screening plant for installation cycle.
Grinding is the required powdering or pulverizing process when customers have a strict demand on final size. ZENITH can provide proper grinding equipment and solutions for different applications, such as XZM Series Ultrafine Grinding Mill whose output size can reach 2500mesh (5um)...
A complete production line cannot work without auxiliaries. At ZENITH, we are able to offer different auxiliary machines with different models to our customers according to actual conditions of projects. We have vibrating feeders, belt conveyors, vibrating screens, sand washers
The types of pressure crushers include jaw crusher, roller crusher, and gyratory crusher. The pressure type crusher uses two hard parts of the machine to press each other to crush rock material. For example, the jaw crushers use the fixed jaw plant and movable jaw plate.
The jaw crusher's main function is to reduce the size of the raw materials or large pieces of material to a sufficiently small size, so as to facilitate the next step of the crushed material. In the quarries and mine materials crushing plant, it is generally used as a primary crusher. The types of jaw crushers are single toggle and double toggle. The construction of the single toggle jaw crusher is compact and simple, and the transmission components such as eccentric shafts are less stressed. Due to the vertical displacement of the movable jaw is small, the material is less excessively broken during processing. Therefore, the wear of the movable jaw plate is less.
Compared with the simple pendulum type, the double toggle type jaw crusher has the advantages of lighter weight, fewer components, a more compact structure and uniform crushing, high productivity. 20-30% higher productivity than a simple swing jaw crusher of the same specification.
Tooth Roller crusher is a new product that is designed and developed according to the structure principle of Gunlock crusher in America. The machine has the advantages of small volume, high crushing ratio (5-8) , low noise, simple structure, convenient maintenance, high productivity, even particle size of crushed materials, low over crushing rate, convenient maintenance, etc. The mall roller crusher is widely used in the mining industry as a secondary crusher.
Gyratory crusher is a new type of crusher that can replace fine jaw crusher and cone crusher. It consists of a concave surface and a conical head, both of which are usually lined with manganese steel. The inner cone has a slight circular movement but doesn't rotate. The gyratory has the advantages of good finely crushing effect, large processing capacity, small vibration, simple maintenance, low cost, and less lining plate wear.
Impact crushers crush materials by impact rather than by pressure. The material is broken in the crushing chamber under the impact force. It can handle materials with side length less than 100-500 mm, with compressive strength up to 350 MPA. It has the advantages of a large crushing ratio and cubic particles after crushing. There are two types of impact crushers: Horizontal Shaft Impact(HSI) Crushers and Vertical Shaft Impact(VSI) Crushers.
In the sand making plant is one of the essential crushers. Cone crusher according to the crushing force is divided into Simmons spring type and hydraulic type. Hydraulic type is divided into single-cylinder and multi-cylinder cone crusher. According to the rotary speed, there are three types: low speed, medium speed and high speed.
The basic structure of cone crusher is similar to that of rotary crusher, but the range is larger. It rotates and presses against the stone on the side of the machine, where it falls into the lower chamber and is crushed again until it falls out of the bottom. Its advantages: reliable structure, high productivity, easy adjustment, and low operation cost.
Hammer crusher(Hammer mill) is broken by an impact between a high-speed hammer and material. This type of crusher is divided into two types: single rotor and double rotor. Single Rotor is divided into reversible and irreversible. Hammer crusher is mainly composed of the rotor, spindle, hammerhead, lining plate and impact plate. And it mainly crushing for coal, salt, chalk, gypsum, brick, limestone and so on. It also used for crushing fiber structure, flexibility, and toughness of strong broken wood, paper, etc.
The advantages of the hammer: larger crushing ratio, high production capacity, uniform products, less over-powder phenomenon, simple structure, light equipment quality, simple operation, and maintenance.
Sand crusher is also called VSI crusher. It is an indispensable equipment for artificial sand manufacturing plant. VSI crusher imported advanced German technology development and production, with the international advanced level. Its performance plays an irreplaceable role in the fine crushing equipment of various materials. There are two types of sand-making machine: stone hit stone and stone hit steel.
The upper and lower hitting guard plate is installed on the crushing cavity wall of the sand making machine. It makes the ore material to be crushed by the impact, friction or high-speed impact between the material and the lining layer formed by the material and the material accelerated by the flywheel when accelerating. The materials do not come into direct contact with the equipment. This method reduces the wear and tear of fittings and prolongs the service life. "Stone hit stone" sand crusher is suitable for material with high abrasion above medium hardness, such as basalt. And the finished product has good grain shape, but the powder content is a little more. So it is more suitable for aggregate shaping.
In the crushing cavity wall of the sand-making machine, the lower hitting guard plate is replaced by the perimeter guard plate. When the ore material is thrown out by the roller, it is directly impacted on the guard plate for many times and the crusher. Under the constant impact, and then the crushing cavity material impact, ore material broken more fully, and the finished material particle size smaller. The "stone hit steel" sand crusher is suitable for small abrasive materials below medium hardness, such as limestone, and the crushing efficiency is high. However, due to crushing depends on the impact, so wear parts are higher. The finished product is slightly worse, it is more suitable for sand-making.
1. 40 years old JXSC Mine Machinery Factory founded in 1985, and we have 40 years of production experience. In the 40 years, we are committed to the development, production, sale of high-quality crushing equipment, mining and mineral processing equipment. We have mature manufacturing technology, excellent engineers, design and manufacture high-yield crushing plant, sand plant mining plant for users.
3. Considerate pre-sale service, after-sale guaranteed service We have a professional sales team to answer all your equipment questions. Take the customer to the factory to see the equipment and free test machine. We provide equipment installation schematic diagram, video installation guide. In some places, our engineers can go to the site to install and debug. All the equipment is guaranteed for one year, except for the wear parts.
Both crusher production line and sand production line basically use vibrating screen. There are many kinds of vibrating screen, which can be divided into circular vibrating screenand linear vibrating screenaccording to the movement track of materials. These two types of screening equipment are usually used in daily production. Whats the
Multi-cylinder hydraulic cone crushers are widely used in the sand aggregate and mining industries, especially in the medium and fine crushing processing systems of medium-hard materials. Weintroduce4 common problems in the operation of cone crusher: abnormal vibration, high noise, easy dirty lubricating oil, high oil return temperature, and introduce how
JXSC Mine Machinery provides stone-crushing solutions for a range of industries including mining and construction. We manufacture three types of machinery, namely, the crushing machine, the sand-making machine, and the mineral processing machine. Various models of these are available as per customer needs. Our products are cost-effective and high-quality. In
Jiangxi Shicheng stone crusher manufacturer is a new and high-tech factory specialized in R&D and manufacturing crushing lines, beneficial equipment,sand-making machinery and grinding plants. Read More
PT ANUGRAH MANDIRI KARYATEK are general supplier and trading company. We also have capability to do contracting and installation for machinery. We are representing products from HOSOKAWA Micron Corporation Japan, which specialist in powder processing system. We are also representing product from ALLGAIER Process Technology.GmbH Germany, which specialist in screening and drying technology.
In the past 30 years, we have focused on the research, development and manufacture of mining crushing equipment, sand making equipment, industrial milling equipment, and keep improving them to build more environmentally friendly equipment.
Ganzhou Eastman Technology Co., Ltd. has for the target market in selling mineral processing equipment for rock crushing/grinding and sand making/washing operations. We provide those machines directly from our owned manufacturing workshop located in Shangyou factory or Shicheng factory based in Ganzhou, Jiangxi, China. So, as a customer you can properly get the most reasonable price equipment, also with promised good quality.Except saling our rock crushing & sand making equipment, we have Mining & Mineral Processing Engineer helping you make the right choice in crushing process and sand making processing. Also, our experienced exports are willing to help you design the perfect product line for your aggregate plant or sand making plant.
You can buy from us almost every material crushing processing equipment starting from crushing, grinding, sand washing & making, classification. And there are many customers cases you can find in our site.
Sand making production line consists of vibrating feeder, Jaw Crusher, Cone Crusher, Impact Crusher (sand-maker), Vibrating Screen, Sand Washer (sand classifier), Belt Conveyor, water treatment system and centralized electronic control system.