March 1, 2008
Screen machines and their accompanying media can mean the difference between finer production and unsaleable products. Here’s a guide to what’s on the market.
by Tina Grady Barbaccia, Senior Editor
Generates 50 Gs of acceleration
The Liwell screen from Allmineral creates a flip-flow or trampoline-like action in order to generate 50 Gs of acceleration, which allows wet, sticky material to be screened at small cutpoints without using water. The screen uses two sets of sideplates that are connected to alternating cross beams, both of which are connected to slider crank mechanism with an eccentric bearing — when one system is drive uphill, the other is drive down. A polyurethane screen mat is connected to crossbeams and is stretched to achieve the flip-flow type motion. This tenses up and overstretches the mats, and the overstretching slightly changes the holes size to allow the screen to self clean the deck. The combination of the high G forces and self-cleaning ability enables the screen to be resistant to both blinding and pegging. The screen is available in sizes up to 10 by 30 feet. According to the company, this screen is particularly useful in applications using a very fine hole size — down to a cutpoint at 50 mesh — and for removing unwanted 200-mesh dust.
Five force amplitude settings
The Prosizer 2612V closed-circuit mobile plant from Astec Mobile Screens features a PEP Vari-Vibe 2612V double-deck, high-frequency screen and horizontal impact crusher. The screen is a 6- by 12-foot top and bottom deck driven by five variable-speed hydraulic vibrators ranging from 0 to 4,200 rpm that are mounted below the screen for directly induced vibrating action. All the vibrators have five force amplitude settings on adjustable slip counterweights, hydraulic controls for variable angle operation, and a rotary tension device for quick screen cloth changes. The top- and bottom-deck discharge chutes are lined with UHMW, aggregate spreader, and a fixed access ladder with a wraparound walkway for easy screen access. According to the company, this is the only self-contained plant on the market today that’s designed to fractionate RAP with a high-frequency screen for higher percentages in hot-mix asphalt designs.
The Vari-Vibe and Duo-Vibe family of high-frequency screens come are available in multiple configurations in stationary and portable structures and in mobile screening plants.
‘No-bearing’ changeout environment
The IS Inclined Vibrating Screen from Metso Minerals combines the company’s Modular Vibrator (MV) with an extra-heavy screen body and was designed with finite element analysis. The screen’s huckbolt construction creates a connection and durability without stress points created by traditional screen-welding methods, according to the manufacturer. It has four bearings per shaft line, which are protected from contamination with the MV unit. The MV unit has a lightweight aluminum end cap that can be removed by hand facilitating counterweight adjustments and inspections and can be easily removed and replaced with a new unit, which has created a “no bearing” changeout environment.
Heavy-duty polyurethane decking
The Density Separator and Intensive Dewatering Screen wet classification system from CFS works well as a sizing screen for 0.5-, 0.75-, 0.85-, 1.0-, and 1.5-mm separations. The 1,200- and 1,800-rpm 45-degree strokes are said to be ideal for these fine separations, and the heavy-duty polyurethane decking is excellent for long life and low wear, according to CFS. The company also makes a step deck screen with two footsteps down the screen, tumbling the material bed at each step. These are used in combination to make coarse and fine sands, which can be blended together by blend gates or percent gates to make specification manufactured sand or concrete sand.
High-wear, tear-resistant wire
W.S. Tyler introduces Ty-Ger Wire, a high-carbon, industrial wire available for high-wear screening applications. Typically, this hard steel wire is only available in larger diameters, however the company says it can now weave these smaller diameter wires in this unique high-carbon alloy. The product is engineered with a special patented drawing process resulting in a high-wear, tear-resistant, and extremely elastic wire.
According to the company, Ty-Ger Wire has up to two times the tensile strength of stainless steel and up to four times the strength of basic steel — with wear life up to five times longer. This woven wire is available for industrial screens, including hooked screen sections. The company also offers a pro-rated warranty program.
Only requires 10 horsepower
The C56 HI-Capacity Dewatering Screen from Derrick Corp. has a screen bed G-force of 8.0, and when paired with the company’s patented high open-area urethane, incoming feeds such as concrete sand, asphalt sands, and mason sands are dewatered to more than 90 percent solids by weight, according to the manufacturer. The single 5 by 15 unit can handle 300 tons per hour and only requires 10 horsepower from a power supply to operate. Small footprint and room requirements make for easy installation and operation of the unit.
Ideal for dry-screening applications
The Dur-X-LiveWire polywire, slotted-wire screen media from Durex Products, Inc. is designed to boost production by eliminating blinding and plugging problems, while providing longer wear life. Available in the company’s proprietary Xtreme high-tensile tempered or stainless steel wire, the screen media is ideal in dry screening applications where materials contain high-moisture content and a high proportion of fines. The screen’s high-strength wires are held in place by molded rubber strips that provide longer wear life and great open area, according to the company. The 60-durometer rubber strips allow optimal flexing action required to keep screen openings clear. The rubber-molded strips are particularly ideal in hot and humid environments.
The screen media is available in the following four slot-type openings: diamond-shaped; Dur-X-Accuslot (alternating “Z” and straight wires that form triangular-shaped openings); herringbone; and straight-wire slot openings (long slot screens that have parallel wires). An optional lap design is available that permits screen replacements without having to adjust adjacent screens. Screens are available with openings up to 2 inches and wire sizes up to 0.250 inches and with overall screen sizes up to 72 inches long by virtually any clamping width.
Triple-deck screen plant
Extec’s largest model in its S-Series, the S-7, features the same double-screen design as the smaller units in the series, but boasts a triple-deck configuration as well as an additional side conveyor. Along with a large feed hopper with optional double-deck vibrating grid and a set of extended conveyors, these features are said to make the S-7 the most productive mobile screen in its class. With a transport weight of 85,142 pounds, the unit is powered by a Deutz BF4M 2012 diesel engine with 74.9 horsepower that meets or exceeds all known emission regulations. It is carried on a large, durable chassis that provides enhanced strength and rigidity while a self-loading hydraulic bogie provides an independent transport capability without the need for low loaders.
Virtually eliminates pegging, blinding
Major Wire’s Flex-Thane combines the company’s Flex-Mat technology with the installation of polyurethane and rubber panels to “virtually eliminate blinding and pegging problems on flat-surface screen decks,” according to the company. The product’s independently vibrating wires, bonded in place with polyurethane strips, provide more open area for greater throughput, higher production, and better efficiency than polyurethane and rubber screens in hard-to-screen applications. The modular panels can be easily installed on most common flat-surface screen decks, similar to traditional polyurethane and rubber panels. The product is available in 1- by 1-foot and 1- by 4-foot panel sizes, as well as metric and mixed dimensions, with a variety of locking systems to fit virtually any flat-surface polyurethane screen deck. It also can be custom-made in 1- by 2-foot and 1- by 3-foot sizes.
Screen stringer system
Polydeck Screen Corp. will debut its PipeTop II Stringer System at ConExpo-Con/Agg, a new design that maximizes versatility from a single frame. Available in three forms — bundled rails for a new screen deck, jigged conversions for changing out an existing frame, or a complete screen deck frame to retrofit an older shaker — PipeTop II is said to offer a variety of production benefits. Its 1/2-inch rails, when coupled with Polydeck’s Maxi screen panel designs, provide high open area that may match wire cloth in many cases. It also offers multiple fastening options from a single frame including PolySnap and traditional pin-style versions. The fastener heads are polyurethane and screw into steel ferrules on the frame rails. If a fastener head becomes worn, it can be removed and replaced individually rather than replacing an entire frame. For applications requiring a changeover to wire cloth, crown adapters fit both fastener head types and offer the ability to change between screen media with a minimal investment of time and money.
Eliminates need for slurry pond
Phoenix Process Equipment Co. has expanded the range of hydrocyclone options in its HG Separator line for aggregate wash plants. The mechanical separation system combines hydrocyclones with dewatering screen technology to produce a dewatered, marketable, solid-phase product from previously discarded fines slurry without using chemical flocculants or coagulants. The slurry is pumped into the hydrocyclone portion of the separator to recover target fines. The hydrocyclone underflow containing the captured fines then reports to a high-frequency dewatering screen, where vibratory forces dewater and convey the recovered material. The underflow from the screen is re-circulated to the hydrocyclones to eliminate loss of recoverable fines. For complete slurry pond elimination, the hydrocyclone overflow reports to a high-rate thickener and belt filter press.
The company now offers high-efficiency units that are said to produce sharper, finer separations throughout a wide range of capacities. According to the company, the separator can reduce slurry pond cleaning costs and create a potentially marketable product, and it can be upgraded to a complete fines dewatering system, which eliminates the need for a slurry pond.
The Screen Machine
Hydraulically adjustable screen angle
The Screen Machine Spyder 516T Portable-Tracked Screening Plant boasts myriad features such as a Caterpillar 312 undercarriage, 11-cubic-yard hopper that can be loaded from three sides, heavy-duty Grade 80 steel construction, a double-deck two-bearing screen, massive unibody structure deep-frame design, and the company’s patented Smooth Start technology. The unit’s screen box features a 5- by 16-foot double-deck two-bearing screen that reaches capacity matched to upwards of 600 tons per hour, depending on material specifications. The U.S. Grade 80 steel screen box features a heavy-duty, wear-resistant plate. The plant’s hydraulically adjustable screen angle adjusts from 8 to 20 degrees to match the screen angle to material for efficient screening. The top deck accepts wire cloth, punch plate, or finger screens, and the bottom deck accepts wire cloth, harp style, or finger screens. The plant can screen four different sizes of material (with optional grizzly) simultaneously and can be controlled via wireless remote control movement and operation. It is also pairs well with the company’s 4043T Impact Crusher.
New construction provides better durability
Unified Screening & Crushing’s Twin Wire Screen was designed for high-impact, top-deck applications. Typically used for 2-inch openings and larger, the company claims this new construction provides greater durability, while maintaining maximum open area. High carbon or Tufflex wire is recommended and can be made to fit any screening area. Special tooling has been designed for various wire diameters to ensure uniform openings on a flat screening surface with a strong lock-crimp construction. In some tested applications, field observations uncovered a 3/8-inch wire outperforming a 5/8-inch diameter, single-wire construction.
Telsmith is introducing a new line of inclined vibrating screens at ConExpo-Con/Agg. The Vibro-King TL series replaces the Vibro-King and Specmaker lines, boasting longer service life, reduced maintenance requirements, and lower operating costs. The new screen features a TL shaft assembly with a revolutionary “Never-Wear” seal design that eliminates contact seals, reducing maintenance and extending service life. All TL shaft assemblies use wide-series bearing and polished shaft-bearing journals for longer life.
Screen plates with 10 times the wear life
The QT-PLUS Screen Plates from Jadco do not stretch, can be designed in any shape, have tapered holes, and are always consistent in sizing accuracy, according to the company. The QT-PLUS material provides wear-resistance to outlast any carbon steel plate or wire cloth, and the company says that it provides up to 10 times the wear life. The perforated screens will not stretch, so no re-tensioning is required. If a specific screen size or hole opening is needed, the company’s CAD team is able to provide unique blueprints for that client’s needs.
Construction Equipment Co.
All hydraulic setup
Construction Equipment Co.’s Screen-It three-deck screen model features an all-hydraulic set up and high portability, similar to the other models in the line. It is capable of producing up to four separate products simultaneously. This model is recommended for a variety of materials, including sand and gravel, rock, concrete, and many other recyclable items.
High-volume mobile screening plant
Astec Mobile Screens expanded its line of Fold ’n Go mobile screening plants with the new Fold ’n Go 2516KT. The track plant is designed to meet high volume demands in quarrying, sand and gravel, and recycling operations. Powered by a 97 horsepower Caterpillar engine, the portable screen features easy-to-reach engine controls and central grease points. The 5- by 16-foot double-deck screen is supported by rubber torsion springs that allow for a smoother operation. Operating angles of the screen box can be hydraulically adjusted for various production and material separation needs.
Cone crushing and screening plant
Metso Minerals will launch its Lokotrack LT200HPS plant to the U.S. market during ConExpo-Con/Agg. The new cone plant is built around the Nordberg HP200 and can process up to 275 tons per hour thanks to its large feed opening. It is said to produce a highly cubical end product and to have excellent reliability. Its Cat C-13 diesel engine meets Tier 3 emission standards and creates 416 horsepower at 2,100 rpm. Variable crusher speed allows the user to optimize the speed for specific liners and feed stock. Two screen options are available: single- or double-deck detachable screens. The standard single-deck screen features a large screening area of 3.9 square meters and mesh size options ranging from 20 to 60 millimeters. The optional double-deck screen enables the simultaneous production of two products. The rotation of the screen can be changed, and the screen module has a hydraulic opening for screen mesh changes. Optional re-circulating conveyors allow for closed-circuit operation. The plant also features the IC600 interactive, intelligent control system to monitor material flow to the cone.
Screen panels up to 50-percent quieter
The Flexi rubber screen panels from Polydeck Screen Corp. provide significant benefits to producers, particularly in applications involving high humidity and/or sticky material, according to the company. The rubber compound used in the screen panels enables the vibrating action of the screen deck to cause the surface of the Flexi panels to quiver, which prevents fines or other sticky material from accumulating. These rubber screen panels are up to 9 decibels — 50 percent — quieter than wire cloth or other steel media and are available in 1- by 2-foot size with openings that range from 1 mm (about 1/32 inches) to 38 mm (about 1-1/2 inches).
Wire and urethane screen support
Unified Screening & Crushing will introduce Superflow, an advanced combination of wire cloth and urethane support strip. This special hybrid product expands the company’s Unified Clean Screen product line, which includes wire cloth, rubber, and urethane screen surfaces and is designed to improve throughput.
Reduces moisture content in sand
The Aggre-Dry Fine Material Washer (FMW) Screen from GreyStone Inc. combines a fine material screw and dewatering screen to produce sand and gravel products with moisture content as low as 8 to 13 percent by weight, according to the company. The dewatering unit only uses 30 horsepower to wash and water up to 100 tons per hour. The manufacturer’s standard FMW screen initially dewaters the material, while the rotation of the dewatering screw simultaneously scrubs the material to help remove surface dirt. The action of the screw flights sends the sand up the inclined tub and ensures that the dewatering screen at the top of the flights will be evenly fed. The vibratory dewater screener then further removes moisture from the sand. This combined process produces a caked, dry sand product that neither an inclined dewatering screw nor a vibratory screen can achieve separately, according to GreyStone.
The screen has several unique features, including the following: a 0.25-mm screen opening reduces the amount of material that can fall through the screen. The feed from the screw allows material to build to a bed depth of 14 inches on the screen, squeezing additional moisture from the sand as the vibratory motors move it along the length of the screen cloth, which further reduces moisture content. The unit also reintroduces the throughs from the screen back into the screw’s washing process, where the screw portion of the unit pushes it to the dewatering screen — eliminating the need for pumps and cyclone sand separation systems and increasing the amount of saleable product.
Features bolt-through construction
Grasan mobile and stationary wet and dry screen plants are available up to 8- by 24- feet in both horizontal and inclined configurations. Standard and custom designs are also available. The screens feature through-bolt construction, replaceable members, crowned screen decks, spring or wedge side tensioning, and walkways with access ladders. Feed boxes and discharge chutes have wear liners. The entire chute assembly may also be removed in one piece to make maintenance easier. The portable units are designed for high mobility with fast setup and are mounted on single-, tandem-, or triple-axle trailers.
Individually replaceable rods
The Samscreen Grizzly Finger Deck features a modular design, individually replaceable rods, and can convert to any deck. Heavy-duty grizzly decks also are available. The heavy-duty grizzly fingers are applicable for crusher feeders. The company also features custom piano wire screens, shape wire with urethane bucker strips, Maxwear high-tensile wire, and stainless steel, which are available for shipment within 24 hours.