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Base Rock Minerals Exercises Flexibility at Mo. Quarry

Thu September 27, 2007 - Midwest Edition
Construction Equipment Guide

Being an independent producer can have its advantages and its disadvantages. While large aggregate producers might have access to greater resources, small aggregate producers often have the advantage of their resourcefulness.

Vendor mandates with national accounts are often the norm for large companies, but smaller companies still have the freedom to look for solutions to their challenges — and try new equipment or parts — without running into a lot of “red tape.”

Base Rock Minerals, in Bonne Terre, Mo., known as the “Minerals Area” approximately 70 mi. south of St. Louis, was established in 1998 — on the site of an older quarry that had opened in 1927. “This site was designed originally to satisfy a lime kiln operation on an adjacent property,” said Base Rock Minerals Quarry Superintendent Mitch Tedder. “The quarry did a little bit of outside sales, but mainly it was a self-serving quarry for the kiln.” The kiln processed high-magnesium dolomitic material for the steel industry. (Lime and limestone are used by steel mills to remove impurities from the iron as it is smelted.)

According to Kerry Bauman, Base Rock Minerals’ quarry manager, its parent company, Vern Bauman Contracting, virtually walked into the quarry purchase opportunity in 1997. The company had a contracting job in the area and approached the quarry to purchase fines for the project. At the same time Vern Bauman discussed purchasing material, he was asked if he wanted to purchase the entire quarry. Bauman also owned a small pit in Bloomsdale. “He bought the property because construction aggregate has a bigger market in this area than steel,” Kerry Bauman, Vern Bauman’s son, said. “It was a great opportunity.”

Kerry had quarry experience from working at a quarry near Barnhart, Mo. Kerry became the quarry manager at Base Rock Minerals, and with Tedder, has helped the quarry to grow to its current size; this year Kerry estimates the quarry will produce at least 800,000 tons (725,700 t).

Base Rock Minerals’ main products are stone for ready-mix concrete, from 0.4 to 0.8 in. (1 to 2 cm), and asphalt chips, from 0.2 to 0.6 (0.4 to 1.8 cm). The company also continues to produce stone for the steel industry — with the neighboring lime kiln still in operation as a steady customer, in addition to steel mills across the country. Material for the steel industry includes 0.5 by 2 in. (1.3 by 5 cm) and 1 by 3 in. (2.5 by 7.6 cm). Using stone from three separate areas of the quarry, the company produces about 25 separate products. With a partially owned asphalt plant on-site, approximately 20 percent of Base Rock Minerals products are internal sales to the asphalt operation, with the remainder sold to outside customers.

Bauman and Tedder are proud of the fact that the plant circuit at Base Rock Minerals is entirely employee-designed and built. Employee pride shows, as well, in the clean operation. “The quarry was a mess when we started,” Tedder noted. “We have been reclaiming as part of cleanup from the old kiln, adding cover and planting vegetation. We’ve got a good MSHA record, and the DNR is pleased with us, too.”

The company blasts about once a week during peak season, with approximately 30,000 tons (27,200 t) dropped in a shot. The pit encompasses 100 acres (40 ha), and material is currently removed from three separate areas within the pit, based on its makeup and market needs.

A Cat 992C feeds a Pioneer 3042 jaw that is fitted with a Deister 4 by 26 ft. (1.2 by 7.9 m) vibrating grizzly feeder. Material is conveyed from the jaw to a Symons 5.5 ft. (1.6 m) standard cone. A Simplicity 8 by 20 ft. (2.4 by 6 m) three-deck screen stockpiles or sends material to a Symons 5.5 in. (13.9 cm) shorthead cone, with that material returning to the Simplicity screen. A Tyler 6 by 16 ft. (1.8 by 4.8 m) two-deck finish screen, and a Smico 3 by 8 ft. (0.9 by 2.4 m) scalping screen to handle oversize material, complete the circuit. All of the equipment at Base Rock Minerals was purchased used. Bauman and Tedder designed the circuit, and employees fabricated and erected the supports that keep all but the jaw crusher off the ground. The circuit can run with a stockpile truck driver and loader operator keeping tabs on production, with the loader operator having control over the feed.

“We can make up to eight products at a time, and we get about 500 to 550 TPH production,” said Tedder.

But a little over a year ago, production numbers were lower for the quarry — with the bottleneck occurring at the 8 by 20 ft. (2.4 by 6 m) screen. “Our bottom deck on the screen was blinding; we had too many rejects, and we couldn’t keep the material clean,” Tedder said. “We were getting 0.5 inches minus, rather than 0.5 in. chip that we needed. We didn’t shut down to clean it —because we couldn’t. It blinded too fast. We just made bad product and had to sell it as base, that’s all.”

Still, Tedder and Bauman knew the quarry could produce better material — if they could stop the blinding problem on the screen. After consulting with their equipment dealer, The G.W. Van Keppel Co., Bauman and Tedder decided to take Van Keppel’s suggestion and use a specific self-cleaning screen media. In 2005, working with Van Keppel and Major Wire’s territory manager, Hank Stindt, they installed Flex-Mat 3 High-Performance, Self-Cleaning Screen Media, by Major Wire Industries Ltd., on the Simplicity screen’s bottom deck.

“The Flex-Mat was more expensive than the woven wire we’d been using,” Tedder said. “And before we committed to using it, we also wanted to check out polyurethane, so we installed the Flex-Mat and some polyurethane (screen cloth) side-by-side on the screen to test it. The polyurethane did okay, but it had fewer openings than the Flex-Mat. It was more expensive, and anytime you got heat near it — from hot iron, or a blow torch — it melted.

“The Flex-Mat stopped the blinding for us — and it cleaned up our product,” he said.

Bauman and Tedder were so pleased with the product quality they produced using Flex-Mat 3 on the bottom deck, that in the spring of 2006, they asked Van Keppel what a flex-mat-type screen cloth could do on the other screen decks.

“Our top and middle decks were pegging 25 to 30 percent,” Bauman said. “The middle deck was really bad; it would first peg, and then blind over because of the pegged rock. We were losing some production because we would have to beat on the deck to break the material loose. We also had to hammer through the pegged material on the top deck. We decided that as good a job as Flex-Mat was doing on the bottom deck, we wanted to try it on all three decks and see if it stopped the pegging problem.”

“Van Keppel didn’t push it with us — we pushed it with them,” Tedder said. “We asked if it could be done; they said it could and we ordered 30 panels of Flex-Mat in one shot.”

Flex-mat-type screen media was introduced to North America in 1996 by Major Wire, launching a separate self-cleaning screen media category that today is offered by several screen media manufacturers. Since its introduction, flex-mat-type screen media has primarily been used on bottom screen decks to prevent the common problem of blinding in fines removal. But as a result of continuous research and development, Major Wire now manufactures Flex-Mat 3 in a large range of wire diameters and opening sizes (from 30 mesh to 4 in.) that can accommodate all material sizes. The screen cloth can be used on all decks — top to bottom — and it solves a variety of problems for producers and contractors.

For a screen to do its job, material must pass from one deck to the next. A flex-mat-type screen cloth on all screen decks can help producers with problems from pegging and blinding:

Top Deck: Because of its independently vibrating wires, a flex-mat-type screen cloth reduces pegging on the top deck, thus reducing or eliminating the need to shut down for cleaning, or to clean the deck after the shift. The material penetrates the screen cloth as it is meant to do, passing through to the middle deck.

Middle Deck: Again, the independent vibration of the flex-mat-type screen cloth’s wires reduces or eliminates pegging and clogging (which often results in blinding, as Base Rock Minerals experienced). The passing material penetrates the cloth to get to the bottom deck better than with woven wire. Production increases, because more material passes per hour than with woven wire. The product is cleaner because the vibrating action of the wires causes the fines to vibrate off the rock, sending both through the cloth.

Bottom Deck: With more aggregate material getting through to the bottom deck, the combination of rock and screen cloth wire vibration on the bottom deck causes the fines to pass through the screen cloth, with clean, sized material coming off the bottom deck as a spec product.

Tedder and Bauman discovered shortly after installing Flex-Mat 3 throughout the Simplicity’s screen decks that their timing was impeccable. “About that time, we got hammered with a need for asphalt chip,” Bauman said. “The asphalt market just took off in this area.”

Base Rock Minerals was able to meet the market’s need with more saleable asphalt chip. “Before, if the chip didn’t clean up enough for us, we had to just throw it on the ground as waste material,” Tedder said. “We increased by half or better what we were previously making in chip, and it’s running clean.”

The managers also discovered that the flex-mat-type screen media allowed the quarry to produce in wet conditions. “We run year-round,” Tedder said. “Before we started using Flex-Mat on all the decks, we had to use dry shot if we were going to run the asphalt chip. If it was wet, from snow or rain, we’d have to run base instead.”

In addition, one ledge from which Base Rock Minerals digs material with an excavator actually rests under several feet of water. “We can dig it out and run it wet either at the end of the day or the next day without a problem,” Tedder said. “We couldn’t do that with woven wire. It’d be too sticky.”

“Other producers in the area can’t crush wet rock at all,” Bauman said. “We can crush in heavy rain, unless the rain stops our belts, and our equipment isn’t covered. It’s got to be a heavy rain for us not to crush. The Flex-Mat makes all the difference in the world.”

Base Rock Minerals runs its Simplicity screen with 2 and 1.1 in. (5 and 2.7 cm) openings in six sections of Flex-Mat 3 on the top deck, depending on the material being produced. The middle deck uses 0.9 and 0.8 in. (2.3 and 2 cm) Flex-Mat 3; the bottom deck uses Flex-Mat 3 with 0.4 and 0.2 in. (1 and 0.5 cm) openings, depending on the product.

Base Rock Minerals continues to work with Van Keppel’s Pat Mueller and Major Wire’s Stindt to fine-tune the screening operation — although screen cloth wear has not been an issue. The quarry has only had to replace its Flex-Mat 3 screen media approximately once a year from wear.

“We’re definitely able to feed more material to the screen. Two years ago, we were running the entire plant at about 400 TPH. Today, we’re running at 550 TPH,” said Bauman. “With the return flow, the Simplicity screen sees at least 750 TPH now without a problem. For a compression crushing operation, Flex-Mat is definitely the answer.”

“In this location, the Flex-Mat has definitely paid for itself. If it had cost twice as much as it did, it still would have paid for itself,” said Tedder. “I know if I was starting a quarry today, and had a low, low budget to work with, Flex-Mat would be in my budget. The return on investment was that quick.”

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