using high frequency screens to

Using High Frequency Screens to

ELIMINATE WASTE,

OVERCOME WET MATERIAL

CUT COSTS AND SAVE ENERGY

ELIMINATE STOCKPILES

ASTEC MOBILE SCREENS, INC., a member of the Astec Industries family, develops, manufactures and markets mobile, portable and stationary screening plants for the crushed stone, sand & gravel, recycle, mining and other material processing industries. Astec Mobile Screens has revolutionized the materials processing industry with the introduction of the Vari-Vibe® and Duo-Vibe® high frequency screens. Astec Mobile Screens manufacturing facility and administrative offices are located in Sterling, Illinois, all products are produced at this facility and shipped directly to our customers as well as through our worldwide distribution channels. We offer offers the broadest line of mobile, stationary and portable screening solutions in the world. Our mission is to provide the most innovative solutions to material processing, while focusing on quality, cost and economic advantage to the producer.

IF YOU WOULD LIKE TO RECIEVE FUTURE PRINTED ISSUES OF THESE MAGAZINES, PLEASE CONTACT ASTEC MOBILE SCREENS AT 800-545-2125 TO BE ADDED TO THE MAILING LIST.

NEW! The ProSizer 2612V is the complete solution for processing RAP millings for the asphalt producer. This closed circuit mobile plant incorporates a double deck PEP Vari-Vibe® high frequency screen with horizontal shaft impactor (HSI) crusher. Hydraulic screen angle adjustment and rotary screen tensioning system can meet the different RAP application demands with ease. This unit has central grease points and easy-to-reach engine controls for routine service. The quick set up time of less than 15 minutes allows the producer to move around to multiple job sites and process RAP back to its original size. This allows the producer to increase RAP usage while adding flexibility and improved control in mix designs

— Volume 3, Number 1

Mining seashells is much more than a gamefor a company that serves contractors inseveral south Florida counties. StewartMining Industries, Inc. of Fort Pierce,Florida focuses its efforts mainly on anaggregate that was formed from seashells:coquina. You will hear more about coquinalater. In the meantime, suffice it to say thatthis material is used extensively in roadbuilding, as well as in residential and com-mercial construction.

Stewart Mining primarily serves Brevard,Indian River, and St. Lucie counties. Thereare three aggregate-processing plants on thecompany’s St. Lucie county site where theyare running two dredges. One plant classifiessand while another grades rock and makessand. The company’s third plant crushes 57and 89 rock into screenings.

Eisenbrandt said they sell to independentcontractors. “We do have a couple ofbuilding-supply organizations that takesome of our sand. But most of it goes togeneral contractors in the housing market.”

Stewart Mining Industries was foundedwhen Nick Stewart entered the mining busi-ness in 1983. The company currently hasfour permitted mining operations in thestate of Florida.

Last July, in order to improve the quarry’soperations, Stewart Mining began using aPTSC 2618VM portable screening plantthey purchased from Astec Mobile Screens.Designed for in-line material processing,this equipment is especially useful forexisting circuits that need more production.It provides the highest screen capacity inthe market for material separation rangingfrom 1 in. (2.4 cm) to 30 mesh.

“We didn’t have a bit of trouble getting itgoing,” Eisenbrandt recalled. “We just putit together, set it in line, and had it runningthe second day it was here. We stood it upon its legs, unfolded it, slid the conveyorsinto place, and went to work with it.”

The plant also fits well with the company’sother equipment. “It’s a good-lookingspread,” Eisenbrandt noted. “We had somegood equipment to put with it. We boughta new vertical-shaft impact crusher threeyears ago that had just been sitting around.We rented a generator and wired it all upand put it to work.”

“We’re crushing down a shell and coquinamix that is coming out of the bottom ofour mine,” Eisenbrandt explained. “We’redredging it up and pumping it about 1,500ft. (450 m) to an elevated screen.”

The coquina that Eisenbrandt mentionedas the company’s primary product is anincompletely consolidated sedimentaryrock that is composed primarily of seashellsor coral. Stewart Mining works with acoquina material consisting of whole andfragmented mollusk shells in a matrix ofsand, cemented by calcite. It has been usedas a building stone in Florida for more than400 years. The Florida DOT even has aseparate specification for Stewart Mining’scoquina: Code 03 Road Base.

“We’re separating it into a 57 size and 89size and then 1-inch plus,” Eisenbrandtsaid. “We’re grinding up the 57 and 89 to

In southern Florida, Coquina has been used

in Florida for yearsas a building stone...and the DOT even hasa specification for it:Code 03 Road Base.

Volume 3, Number 1 — Page 9

make this rock screening. We’re also sellingsome of the 57 size to local contractors.”The company is also selling coquina rock.

The Stewart Mining operation does faceseveral challenges that the Astec MobileScreens plant has helped overcome. “We’revery pleased with the plant,” Eisenbrandtnoted. “This coquina rock has a lot of sili-con in it, so it’s very abrasive. We boughtsome urethane decks for it. We are usingone of those with two wire screens aboveit. It’s doing a really good job. And ourcustomers love the product.”

Eisenbrandt pointed out that Florida isnotorious for having wet material that mustbe run through the screens. “The highmoisture content in our product required usto go to a 100-percent setting on the plant’svibrators in order to eliminate blinding.With this setup, we have no blinding at all.

“We are in this market for the long haul. Weare going to be producing for years into thefuture. And I believe this equipment willprobably still be with us.” •AMJ•

HOW TO LEARN MORE ABOUT THIS EQUIPMENT:Call Ron Earl at Astec Mobile Screens: 800-545-2125 or 815-626-6374 • E-mail: [email protected]

The PTSC 2618VM from Astec Mobile Screens is a portable screening plant for in-line materialprocessing. As shown here, it features a two-deck PEP Vari-Vibe® high-frequency screen.

it’s not a shell game

— Volume 3, Number 1

They took dolomite...a product that was

thought to beessentially nothing but

a waste material...and they found a way to

make two saleable products.

An aggregate mining company in southeastMissouri recently increased its productiondramatically and opened up new marketsby turning what had been consideredwaste material from their quarry into verysaleable products.

Williamsville Stone Company is located onthe Black River 10 miles north of PoplarBluff, Missouri. Williamsville Stone is per-fectly situated to fill the diverse aggregateneeds of southern Missouri and northernArkansas. Originally a division of theClinton Companies, it became part of anacquisition by Delta Companies, Inc. in1999. Historically, Williamsville Stoneproduced sand and gravel but, in 2001,they shifted their focus to dolomite. Theshift brought a dramatic increase in pro-duction, from 300,000 tons (272,000 tonnes)to 900,000 tons (816,500 tonnes) per year.The key to this remarkable increase wasthe production of two new by-productsfrom the limestone quarry’s previouslywasted, 1-in. (2.5-cm) dolomite material.

According to Zaach Green, the equipmentmanager for Williamsville Stone, thecompany’s new products are agriculturallime and manufactured sand, which arefrequently referred to in the industry asag lime and mansand. While ag lime isused throughout the heavily farmed

region, the area also lends itself to the saleof mansand. Several area highways haverecently undergone major reconstructionprojects, and other nearby road improve-ments are scheduled.

“Our market for the ag lime is the localfarming community around here and allover the Missouri Bootheel,” explainedGreen. “The other major by-product is themansand, which is used primarily in roadconstruction.” He said a constructioncompany located at Williamsville Stone’squarry uses their mansand extensively.

Taking advantage of this once-wastedmaterial—the dolomite—was easy. Theoperation’s secondary crushing and screen-

ing plants were recently upgraded, therebyincreasing production capacity of the 40-year-old Williamsville Stone quarry tomore than 600 tons (545 tonnes) per hour.

A big part of this capacity increase wasmade possible by equipment additions. Thecompany utilizes two screening plants fromAstec Mobile Screens, Inc. One of them isa 6 x 18-ft. (1.8 x 5.5-m) double-deck unitand the other is a 6 x 24-ft. (1.8 x 7.3-m)single-deck unit.

The high-frequency screens provide anaggressive screen vibration that is directlyapplied to the screen media. This allowsextremely high screen capacity, as well asfines removal, chip sizing, and the produc-tion of dry manufactured sand. In otherwords, the new screen from Astec MobileScreens was the perfect solution to thequarry’s wasted-material problem.

“It’s been a good piece of equipment forus,” Green said. “Before we got it, we had1/4-in. (0.6-cm) minus product that wasbasically waste product for us. We had torun it through a sand screw and we werewasting a lot of the dust.”

An Astec Mobile Screens PSP 2618VMplant was set up so that the managementof Williamsville Stone could watch as theequipment was demonstrated. They wantedto make sure the basic design was going

Volume 3, Number 1 — Page 13

to work in their environment. “It worked,”Green recalled. “So then, we put in the1624V. Now, we take our raw materialdirectly out of our bin and keep it dry withcovered conveyors, all the way up to that1624V. And then we separate out the dust—which is the ag lime—on a 16 mesh.That cleans up our 1-in. (2.5-cm) minus toa mansand product that we can make veryconsistently. Essentially, this unit makestwo products at the same time.”

The equipment was installed in 2002. Theresult of the acquisition was one of thoserare win-win situations for WilliamsvilleStone. According to Green, the plant hasallowed the company to gain access to newmarkets—and it has been operating basic-ally without any problems.

“We took a product that was a waste andmade two saleable products out of it,”Green said. “It’s a good result. The equip-ment works very well.”

HOW TO LEARN MORE ABOUT THIS EQUIPMENT:Call Ron Earl at Astec Mobile Screens: 800-545-2125 or 815-626-6374 • E-mail: [email protected]

And Green noted that the original conceptwas not a hard sell to management.

“We presented the financials of the projectand they made sense to everyone. We wentthrough it without any problem. Everythingstayed on schedule. The equipment wasrunning on schedule—and it made theproduct like we thought it would. This isone of our better operations.

“It’s a very nice plant.” •AMJ•

HOT-MIX MAGAZINE 24 VOLUME 12, NUMBER 1

A BIG STEP FORWARDIN SOUTH AFRICA

WHEN TECHNOLOGY leapsahead, there are always afew organizations that have

the enterprise and the initiative tokeep up with it. The emergence offractionated reclaimed asphaltpavement or FRAP (usually calledRAP in North America) as both acost and energy saver is a goodexample: A few companies areusing it, but many others are stillwaiting to see what happens.

The few early adapters includeMuch Asphalt (Pty) Limited, aMurray & Roberts company thathas its headquarters in Capetown,South Africa. Much Asphalt is aleading hot-mix asphalt (HMA)producer in that part of the world.The company has been supplyinga wide variety of HMA mixes for alltypes of roads since it was formedin 1965. This producer is alwayswatching technology as it movesforward. The emergence of FRAPas a resource is a good example.

“FRAP is still an unusual type ofproduct for a producer to use in newmixes,” said Brian Neville, branchmanager of Much Asphalt’sRoodepoort Operation. “A lot ofengineers around here are slowlybecoming educated in the use ofthis material. There is still a bit ofa stigma associated with it.People tend to think of FRAP as awaste material, not as a qualitymaterial. It is not a product that theengineers around here readily use.FRAP is not yet the accepted norm—but it is coming along, slowlyand surely.”

Much Asphalt made a commitmentto using FRAP in July 2006 whenthey bought an Astec MobileScreens Fold ‘n Go® screeningplant from Osborn EngineeredProducts of Johannesburg, SouthAfrica. The company already hada stockpile that consisted of morethan 175,000 tons (160,000 tonnes)of FRAP. A good part of that stock-

pile needed to be processed so itcould be used in producing newHMA mix for the rehabilitation of theOR Tambo International Airport(formerly called the JohannesburgInternational Airport). The companyhad intended to have the FRAPscreened by a subcontractor, butwhen management realized howmuch could be saved by doing itinternally, the decision was madeto buy the Fold ‘n Go plant.

“We purchased a Model 2612DFold ‘n Go screening plant to processrecycled material before feeding itback into our new asphalt mixes,”said Neville.

“Aggregates of many kinds arehigh-demand commodities inSouth Africa, so it makes goodeconomic sense to start lookingat recycling FRAP material in ourmixes. Quite a few of our plantshave sizeable stockpiles of mate-rial that can be recycled. That was

really the driving force behind thedecision to purchase the Fold ‘nGo mobile screen: to process thatmaterial and use it again.”

Neville said the amount of FRAPthat is used in new mixes variesfrom project to project. On therecent rehabilitation project at theOR Tambo International Airport inJohannesburg, South Africa, forexample, Much Asphalt wasallowed to run 10 percent FRAPin their mix.

“We have also used FRAP on alot of our sundry work where thespecifications are not so tight.Those projects range in size from550 tons (500 tonnes) to 11,000tons (10,000 tonnes). Anythingover that, we would classify as alarge project and there wouldnormally be much tighter specifi-cations that would limit the use ofRAP. As I said, some of the con-sulting engineers here in South


FOR INFORMATIONabout the wide rangeof products offered byAstec Mobile Screens,

contact Ron Earl:800-545-2145

Fax: 815-626-6430 • E-mail:[email protected]

Much Asphalt, a Murray & Roberts company, is currently using reclaimed asphalt pavement (RAP) as recycled mate-rial in its new hot-mix asphalt (HMA) mixes at several of its plants in South Africa. The company purchased a Model2612D Fold ‘n Go screening plant from Astec Mobile Screens in July 2006 to screen and process the RAP materi-al into two sizes. The company’s Fold ‘n Go plant includes a double-deck PEP Duo-Vibe® dual-frequency screen andthree on-board stacking conveyors (as shown on the facing page). There is also a high-capacity feed hopper with ascissor-action grizzly (top photo) and a wrap-around screen walkway and access ladder (bottom photo) for personnelconvenience and safety. According to Brian Neville, branch manager of Much Asphalt’s Roodepoort Operation, thedecision to begin recycling RAP material into new mixes has proven to be a wise move.

The concept of recycling old asphaltinto new mixes has not yet caught on with

all of the country’s engineers and consultants,but this producer has already started doing it.

Africa do not yet want us to use iton major projects.”

Neville explained that at MuchAsphalt’s Roodepoort Operation,they are screening the FRAP mate-rial to two useable sizes beforeincorporating it into new mixes:0.35 in. to 0.55 in. (9mm to 14mm)and minus-0.35 in. (minus-9mm).“Those sizes can be used in about95 percent of the asphalt mixesthat we make,” said Neville. “Theoversized material is broken downand sent back for additional pro-cessing, of course.”

Neville had a few more positivecomments about the new plant:

“The Fold ‘n Go screening plant isworking very well for us. We haveprobably screened about 16,500tons (15,000 tonnes) of recycle hereat this site—and we are busy work-ing through a very big stockpile atthe moment. The new machine isworking very well.”

When asked what he might say toanother HMA producer who wasconsidering moving ahead to pro-cessing and recycling FRAP,Neville’s reply was remarkablysimple and straightforward:

“With aggregate materials being acommodity with such high demandin a very buoyant constructioneconomy, using FRAP is the onlyway to go. You just have to do it.There are other reasons to do it,of course, including the positiveenvironmental impact that recy-cling provides. But using FRAPmaterial just makes sense. And Idon’t think anyone can put forthan argument that would convinceme otherwise.

“If another asphalt producer in theregion came to me and asked mefor my advice, I would simply tellhim: ‘Yes, absolutely. It’s the wayto go.’” ▼▼▲▲▼▼


ANYONE WHO IS CONSIDERINGthe potential value of usingreclaimed asphalt pavement

(RAP) in their hot-mix asphalt(HMA) mixes should factor in thiscommon-sense point:

It’s not a matter of if—or even when—RAP will become

a key part ofeveryday hot-mix production.

The move towardusing RAP is underway

right now.It was that common-sense pointthat prompted C.R. Jackson, Inc.,an HMA producer headquartered inColumbia, South Carolina, to adda new piece of equipment to theirgrowing array of production tools.Clarke DeHart, vice president atC.R. Jackson, recently voiced hisopinion about RAP. He said thatalthough the use of RAP in HMAmixes was considered to be anadded benefit by some producersin the past, it will soon becomean economic necessity for almostall producers.

“As prices increase in the asphaltindustry, the use of RAP is goingto move from the back burner tothe front burner,” said DeHartwith emphasis.”

The C.R. Jackson company hasbeen in business since 1972 whenits founder, Richard Jackson,began offering grading, clearing,and utility work to homebuildersin the Columbia, South Carolinaarea. In 1989, the company pur-chased its first HMA plant, therebyestablishing itself as a full-servicesite contractor.

Today, the company operates twoHMA facilities: an Astec Double

Barrel® dryer/mixer plant locatedin Columbia, and a Cedarapidsplant in Richburg, South Carolina.A major part of the firm’s businessinvolves highway paving projects,so when its state department oftransportation started allowinghigher percentages of RAP in themixes, the management of C.R.Jackson immediately welcomedthe opportunity to expand theirRAP-handling capabilities.

Accordingly, in early 2006, thecompany purchased an AstecMobile Screens Fold ‘n Go® 2612Vmobile screening plant for thepurpose of fractionating RAP.

“The percentages of RAP allowedon state jobs are different forevery mix,” said Dehart, “but weare usually able to run as high as15 or 20 percent. That’s the mainreason we bought the Fold ‘n Goscreening plant: So we would beable to put that higher percentageof RAP in there.”The Fold ‘n Go 2612V mobilescreening plant features a PEPVari-Vibe® 2612V double-deckhigh-frequency screen. The unit’s6 x 12-ft. (1.8 x 3.7-m) top andbottom decks are driven by fivevariable-speed hydraulic vibrators(0 to 4,200 RPM) that are mount-ed below the screen for directly-induced vibrating action. All of thevibrators have five force-amplitudesettings on adjustable slip counter-weights and hydraulic controlsfor variable angle operation. Theplant can produce up to 300 tph(454 tonnes per hour) or more.At the C.R. Jackson facility, theFold ‘n Go plant is placed behind aTelsmith crusher. DeHart explainedthat this is because the company’s

FOCUSING ON RAP PERCENTAGES

When the DOT started allowinghigher percentages of RAP,

this company immediately expandedits RAP-handling capabilities

with a mobile screening plant fromAstec Mobile Screens.

FOCUSING ON RAP PERCENTAGES


FOR MORE INFORMATIONabout the wide range of products offered by Astec Mobile Screens,

contact Ron Earl at Astec Mobile Screens:800-545-2145

Fax: 815-626-6430 • E-mail: [email protected]

RAP comes from various sources:some of it is milled material, someof it is in chunks, and some of it isplant waste. As a result, the sizeof the RAP can be unpredictable.

“We originally tried running onlystraight millings through the Fold‘n Go unit without any prep. But ifanything was in there other thanstraight millings, we ended up witha good bit of oversized material,”said DeHart. “We found that itwas better to prep the material byrunning it through the Telsmithcrusher. Our overs have gone tovirtually nothing at all.”

Two sizes of RAP are producedusing the screening plant: minus4 and plus 4/minus 0.5. Thesetwo sizes can then be fed into theAstec HMA plant’s multiple RAPbins, allowing the company toachieve higher-quality mixes withlarger RAP percentages.

“When we made the move fromrunning virgin mixes to mixes withRAP in them, our quality did notsuffer at all! It just was not anissue,” said DeHart. “There are alot of people who think that whenyou start putting unprocessedmaterial in there, you will see avalue decline. But we treat it justlike virgin aggregate and put thesame amount of value on it. Indoing that, we have been allowedto increase our percentages andrun RAP in mixes that we hadn’tbeen able to before. We are veryhappy with it.”

In addition to fractionating RAP atthe company’s Columbia location,C.R. Jackson utilizes the Fold ‘nGo plant’s mobility to provide itsscreening features to its Richburgfacility, as well as to SatterfieldConstruction, in Greenwood, SouthCarolina.

“We’ve moved it four times in thesix months that we’ve had theunit,” said DeHart. “It’s very easy tomove. It only takes the operator

one hour to fold it up and get itready to go. Of course, then hehas to clean it before we can takeit out on the road. And then, onceit’s at the new site, it only takesabout one other hour to set it upand get it running.”

DeHart said the same operator isin charge of the Fold ‘n Go mobilescreening plant, no matter whereit is doing the work. “He does itall—everything that has to do withthe screening plant—including run-ning the loader,” said DeHart. “Heis assigned to that one machine.Wherever it goes, he goes. Hestays with it, he operates it, andhe maintains it.”

The ease of use was a key pointin the company’s decision to buythis particular unit, added DeHart.

“The operator, Gary Gergen, thinksit’s a neat machine. We used tohave an old, off-brand screenerthat just would not do what hewanted it to do,” he said. “I kepttelling him that we had a Fold ‘nGo on order and that it was goingto work much better. And withintwo days of delivery, he was veryhappy. He is very satisfied withhis new equipment.”

Providing their employees withthe right equipment for the job isa central philosophy maintainedRichard Jackson, said DeHart.

“Richard Jackson’s main businessphilosophy is sharply focused onthe people—not the people whoare in management, but everyoneout there who works and carriesthe load for these companies. Wetry to buy new equipment thatour people will have confidencein, and that is easy to use. Andthis equipment certainly meetsthat criteria.

“The Fold ‘n Go screening plant isa good piece of equipment. It iseasy to set up. It is easy to use.And it is certainly easy to producea quality product.” ▼▲▼

The management team at C.R.Jackson, Inc. made a quickdecision to begin fractionatingRAP as material costs climbed.They purchased this AstecMobile Screens Fold ‘n Go2612V mobile screening plant(shown above in profile view)for the sole purpose of fraction-ating RAP.

The rough RAP is first reducedin size by a Telsmith crusher(which is outside of the framein the photo on the left) and isthen screened to remove any-thing that is still oversize.

Then it moves up to a PEPVari-Vibe® double-deck screenwhere it is separated—or frac-tionated—into three differentsizes. The aerial view (below)provides a view of the threestockpiles that are the result ofthe Fold ‘n Go screening plant’sefficient process.

using high frequency screens to

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