May 2010

Resourceful With Waste

You can waste your money discarding rubble and debris, or you can manage that waste as a resource and save some money.

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Successful grading and excavating contractors are, if anything, resourceful when it comes to meeting a challenge. The worst recession in memory for most of them has highlighted the value of making the most of every available resource. Those resources include materials once considered a costly disposal problem—such materials as stumps, logs, and treetops left from land-clearing operations and chunks of concrete, asphalt, and rocks littering a demolition site in preparation for redevelopment activities.

That’s where onsite recycling can pay off. Self-propelled, track-mounted grinders can maneuver easily up and down grades and in and out of muddy areas to process greenwaste into hog fuel and mulch. Meanwhile, tracks enable engine-driven compact crushers to move around a job site as they convert concrete and asphalt rubble, rock, bricks, and blocks into material for use on the project as a valuable aggregate for slabs, sidewalks, parking lots, streets, or highways.

D.J. Cavaliere co-owns Cor Equipment Sales in Stamford, CT. A dealer for Rubble Master Compact Recyclers, www.rubblemaster.com, his company serves contractors in a seven-state region extending from Pennsylvania to New Hampshire. They are split fairly evenly between two types: those who provide crusher services for customers having trouble finding a place to dispose of their concrete and asphalt debris; and contractors doing site development and grading and excavating work who want to recycle their own concrete and asphalt rubble into usable construction materials. “These contractors don’t want to pay to dump this waste and then pay again to buy and truck in new aggregate,” he says. “More and more contractors want to process their own materials, which may be worth from about $10 to $20 a ton.

Most of his sales start out as rentals, he notes. Although sales have dropped during this recession, Cavaliere reports, rentals have increased. “These days, contractors are looking for different avenues to increase efficiency in their business,” he says.

For land-clearing operations, track-mounted grinders offer several advantages over towed wheel grinders, notes Tim Wenger, president and sales manager for CW Mill Equipment Co. Inc., which makes the HogZilla line of tub and horizontal grinders, www.hogzilla.com. “You don’t have to clear a road to move a track grinder around a job site,” he says. “Also, because they are remotely controlled, they’re extremely versatile. A loader or excavator operator can walk a track grinder around with them to make grinding a one-man operation. That same operator can bring the machine to the woodwaste and load the material into it. You don’t need a separate operator and machine to push material to the grinder and another operator and a different machine to feed it.”

Photo: CW Mill Why throw away good ground cover?

Machine Differences
Manufacturers offer two types of crushers for reducing rock, concrete, asphalt, brick, and the like into recyclable construction materials. An impact crusher features steel blow bars mounted on a flywheel rotor inside a crushing chamber. As this large metal mass rotates, the blow bars, spinning at a high rate, break the material on impact and shatter the debris. This material must then pass between the spinning rotor and the impact wall at a predetermined “gap.” Any material too large to pass through this space is impacted with the rotor until small enough to do so. This material then drops to a moving belt that conveys the crushed materials out of the machine.

A jaw crusher, used primarily with virgin rock, produces aggregate and rock fill by squeezing rock between a fixed plate or jaw and a moveable plate, the other jaw. When viewed from the side, the two plates are mounted to form a V-shape so that the opening between them is wider at the top than at the bottom, similar to a funnel. Rock, larger than the bottom opening, enters the crusher from the top and becomes lodged between the two plates. The moveable jaw plate then exerts force on the rock, compressing it against the fixed plate. The size of the final crushed product is determined by the size of the gap between the bottoms of the two plates.

One of the latest advances in the design of compact mobile crusher is a 16-ton, remote-controlled track unit, which can be transported on a trailer pulled by a dump truck and which can operate either as jaw or an impact crusher by unbolting one type of crushing mechanism and bolting on the other. “That conversion takes less than an hour,” says Bob Rossi. He’s vice-president of R.R. Equipment Co., which designed and produces the machine at its plant in Lancaster, SC.

Called the Rebel Crusher, www.rrequipment.com, it was introduced two years ago. The patent-pending machine features a 20-inch-by-36-inch feed opening and can crush rock and recycle debris down to as small as three-quarters-of-an-inch, Rossi reports. It comes standard with a screen to regulate size of the finished product. Options include a self-cleaning permanent magnet, a two-deck sizing screen, and three folding-screen stockpile conveyors.

The machine is designed specifically for small to medium contractors, Rossi notes. “We build this crusher for contractors who need a mobile machine occasionally to work in confined areas, who don’t have a huge amount of material to process on the site, and who don’t want to pay the price of a larger crusher,” he says.

Komplet Italia S.r.l. makes two even smaller mobile-track jaw crushers for crushing glass, porcelain, marble, granite, bricks, blocks, asphalt, and reinforced concrete. The remote-controlled Lemtrack 48-25, which weighs 7,200 pounds, includes a feeding system.

“You can tow it behind a pickup truck on a standard 5-ton equipment and feed it with a mini-excavator or skid-steer loader,” says Nick Baker, president of Compact Concrete Crushers, the North American distributor for Komplet. “This machine can produce a product ranging in size from three-eighths of an inch to three-and-one-eighths inches and typically process about 15 tons per hour in normal operation.”

It’s designed for contractors who usually do smaller projects, like sidewalks, driveways, patios, and swimming pool enclosures, he reports.

Normal production for the 12.5-ton Lemtrack 60-40 model, which has a feed opening of 20 inches by 24 inches, is around 60 tons per hour of three-quarter-inch to three-and-seven-eighths-inch product, Baker reports. Options for the remote-controlled mobile crusher include a rebar separator and a dust-suppression system.

“This machine can handle many of the same jobs as a large, more expensive crusher,” he says. “Of course, this smaller machine will take more time to complete the job, but it has a lower price and much lower operating costs.”

Two types of grinders are available for processing woodwaste. Both use a series of hammers or cutting tools mounted on a shaft, which rotates at high speeds, to reduce logs, stumps, and brush to the desired size. The size of the finished material is controlled by the size of the openings in a screen. A tub grinder features a rotating tub with an open top. Once fed into the tub, the woodwaste passes into the mill. A horizontal grinder, on the other hand, features a horizontal conveyor, which feeds the material through a rectangular opening into the mill. Typically, a self-propelled track grinder costs about $75,000 more than a towable wheel model with similar production capabilities, Wenger reports.

Owning and operating a grinder for processing woodwaste left from land-clearing operations isn’t for everyone, including smaller contractors, says Tee Ray, president of Bob Ray Co. in Louisville, KY. The list of services offered by the company, which operates in its home state as well as Indiana, Ohio, and Tennessee, includes clearing land and grinding woodwaste into hog fuel and landscape mulch.

The company owns a Bandit 3680T and two 4680T Beast Recycler horizontal track grinders, www.banditchippers.com.

“There’s a night-and-day difference between buying a grinder, which can cost upwards of $750,000, and buying a dozer or an excavator,” he says. “You can’t just purchase a grinder and start grinding. It takes a tremendous amount of training in preparing material for grinding and feeding it into the machine properly if you want to keep production up. It also requires a lot of maintenance. In a normal workday, we’ll grind for six hours and spend the last two hours on maintenance, such as greasing, checking fluid levels and air filters, ensuring that the teeth, hammers, and cutter bars in the cutter mill are in good condition and everything is within specifications. Sure, you can spend seven-and-a-half hours grinding and half an hour on maintenance. But, the next day, your production will be down.”

Recycling Wood and Asphalt
In Bellingham, WA, Barker’s Woodchipping Service Inc. has been clearing forestland for residential and agricultural development and road construction projects since the early 1990s. The company grinds logs, treetops, and stumps into hog fuel to power cogeneration plants and, occasionally, into mulch for controlling erosion on construction sites. Last year, the clearing and grinding projects ranged in size from a 1-acre parcel for a new house to an 80-acre site for a raspberry farm.

At one time, the company used tub grinders mounted on wheels to covert woodwaste into a marketable product. However, since 2008, a track-mounted horizontal grinder, the company’s first horizontal model, has been doing the work.

“We get better production from the horizontal-style grinder than the older tub grinders we once used, although the technology of the newer tub grinders has improved quite a bit since we had ours,” says Herb Barker, president of the company.

The steel tracks add to the grinder’s productivity, he notes. “It seems like the ground is always wet and muddy here,” Barker says. “But that’s not a problem with the tracks. They’re so much nicer than trying to drag a rubber-tired grinder out of the mud. Sometimes, it would take us all day just to pull one of those machines into a job site. With the tracks, mud and steeper ground aren’t a problem. We can move the grinder wherever and whenever we need to and can work all year long.”

Barker bought his current horizontal grinder, a DiamondZ DZH4000TK, in 2008, www.diamondz.com. Usually, he loads the remote-controlled machine with his Volvo 210 log loader. Equipped with a rotating grapple, it makes feeding the grinder easier than using his Hitachi 300 excavator, which is used in his grinding operations mostly for pulling out tree stumps, and gathering brush.

To produce hog fuel, which he sells to a pulp-and-paper manufacturer for use in generating electricity and steam, he grinds the wood to about a 6-inch-minus size. He makes the same size material for mulch. In this case, the processed woodwaste is spread about 6 inches thick to cover bare ground on newly constructed wetland mitigation sites.

The bane of crushers and grinders is steel and other hard metals hidden within the rubble and debris. Ranging from rebar to hand tools, these hard materials can cause a major maintenance headache. Although his compact impact crusher can handle some rebar, depending on the final size of the processed material, custom crushing contractor Paul White says the most important job of his crusher operator is to make sure no steel gets into the crushing chamber. “Steel going through a crusher is not a pretty picture,” he says. “If the piece is big enough, it can take a chunk out of the impactor.”

White, who owns Bulldog Crushing in Indianapolis, IN, uses his mobile compact crusher, a Western Retek Supertrak 1310i model, www.westernretek.com, to recycle asphalt, concrete, rock, and bricks for construction contractors and other customers. Depending on their needs, he reduces this rubble to sizes ranging from about 3 inches down to dust.

In the case of asphalt, for example, he usually crushes it to a one-half to three-quarter-inch material. “Depending on where and how it will be used, this material may be blended at the rate of 15% to 28% to produce new asphalt,” he reports.

Customers who don’t reuse the crushed material as a sub-base for roads, sell it to other contractors who incorporate it in their projects, he says.

Tubs on Tracks
At one time, Joey Adams and his brother Lance of Waco, GA, were grading contractors. But in 2002 they downsized, forming Adams Clearing to focus strictly on clearing land, mostly for road construction and commercial site development projects. Their first grinder, which they bought two years later, was a HogZilla wheel model. In 2007, they replaced it with a HogZilla HTC-1462T self-propelled track-drive tub grinder. A year after that, they added a second machine of that same model.

“We really like the track grinders,” Joey Adams says. “They’re so much easier to maneuver around the job site, whether the ground is wet or dry. When the ground was wet, we could hardly get the wheel grinder around the job site using a 10-ton, 6-by-6 military truck to pull it. Also, with the tracks, we can just walk the grinders from one pile of stumps and tree debris to another.”

The brothers use the machines with various size screens to grind tree debris into 1-inch to 7-inch material that they sell to paper mills for powering boilers or electrical generators.

Among the features that Adams likes about the grinders is the torque converter drive for the hammer mill. “It’s virtually trouble-free and requires no maintenance,” he says. “Also, the machine is built simply, without a lot of electronic controls, so it’s easy for us to work on it. Because it uses some of the same parts in other types of equipment, parts are available from a number of different suppliers.”

Even with the downturn in the economy, the Adamses have continued to find regular work for the two grinders. “The only reason we’ve been able to keep busy is our really good customer base,” Adams says.

David Littlefield, Kirbyville, TX, is another grinder owner who appreciates the value of recycling green woodwaste. In 1983, he started a land-clearing company, Littlefield Dozer, removing stumps, logs, and other slash from areas being prepared for development. These early land-clearing projects ranged in size from home sites and farm fields to shopping centers. “Back then, we either piled up all the wood debris and burned it or spent a lot of time hauling it to a landfill,” Littlefield says. “I thought there had to be a better way to than just wasting this stuff.”

That’s when he began an extensive investigation of grinders, attending equipment shows, studying product brochures, and talking with manufacturers and owners of grinders. He settled on a DiamondZ 1036 tub grinder, with a 10-foot diameter tub and mounted on wheels, and started grinding tree trunks, branches, and stumps to produce hog fuel to run boilers at paper mills. That machine is now used as a backup to his two newest grinders—both DiamondZ model DZH4000TK track-mounted horizontal grinders—which he and his son operate. Littlefield bought one of them in 2008 and the other last year. Each is stationed at a different paper mill.

Using Caterpillar 315 excavators to feed the machines, the grinders run about 10 hours a day, he reports, during which they produce about 2,500 yards of fuel. The tracks make moving the remote-controlled horizontal grinders, each of which weighs more than 90,000 pounds, easier than using a truck to pull a wheel grinder, he says.

“From time to time, we have to move the grinders to clean out from underneath them or to grind at a different location at the plant,” Littlefield says. “I don’t to bring in a big truck to do that. Usually, we run the grinders on concrete. But, they can also go over soft or muddy ground, where I may need to throw down some mats to keep the heavy machines from sinking.”

He continues to use his original wheel-mounted tub grinder. “If we get caught up on grinding at one mill, we’ll take that machine to help out at the other mill.” 

Author's Bio: Guest author Greg Northcutt writes frequently on construction and business issues.