September 2009

Fuel for a Green Economy

Processors find reasons to be optimistic about the short- and long-term prospects for the C&D refuse market sector.

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Photo: Bandit Industries

By Don Talend

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MSW managers looking to diversify their businesses should find encouragement in the experiences of several construction and demolition (C&D) material processors around the country who are succeeding for two reasons. First, amid the protracted, severe recession that had begun about 16 months earlier, they were holding their own or even thriving. Second, they were tapping into markets for waste materials, particularly wood, that could power a potentially emerging “green economy” in the years ahead.

Equipment Allows Diversification
Several C&D processors across the country are finding that advances in machinery are allowing them to diversify their operations and separate materials with increasing cost effectiveness.

Terry Gillis, general manager, has found that diversification has paid dividends for Recovery1 of Tacoma, WA. In 1993, the company began operations with the intention of making wood fuel and wood pulp—which owed its high prices to low supplies—for recycled paper manufacturers. Today the company processes about 70,000 tons annually and provides 21 different recycled C&D products for resale, including gypsum for portland cement, bailed plastics, carpet, carpet padding, and cardboard, as well as rocks, bricks, concrete, porcelain, and glass for aggregates.

In mid-2007, in an effort to reduce maintenance and energy-consumption costs, Gillis altered his processes by investing in a new SSI Shredding Systems Pri-Max PR-4000 primary reducer, which is located upstream of Recovery1’s 600-horsepower West Salem Machinery model 5472 vertical feed grinder, also known as a hammermill. Previously, the company employed one 1,000-horsepower swing-hammer hog mill, and counting so much on that one machine resulted in high operating costs, says Gillis.

The low-speed, high-torque Pri-Max PR-4000 operates at a typical speed of about 58 rpm, compared with a typical 1,000 rpm in the hammermill. During primary reduction, most steel pieces that would damage machinery are liberated from the feed and captured by an overhead magnet, and the material is conveyed across a short sorting line and under a magnetic head pulley and then into the hammermill for final grinding. Gillis points out that a magnetic excavator attachment and a reverse gear on the Pri-Max machine also keep steel infeed to the processing machinery at a minimum. The Pri-Max PR-4000 has taken stress off of the hammermill and allowed the company to start recycling railroad ties, which often contain steel spikes or even rail pieces, says Gillis. The machine, which processes up to 75 tons per hour, also reduces the amount of time that excavator operators spend breaking up large material and provides a more even flow of material. Material is fed into the hammermill via an infeed chute and drops into the grinding chamber. A massive rotor assembly with 27 swing hammers weighing 150 pounds each that are equipped with reversible and replaceable tips crushes the material against a crushing door, shears it against an anvil, and then drags it over modular screen grates resulting in typical reductions to about 18 inches.

“Going with a two-stage system has resulted in a significantly lower electric bill as well as a significantly lower maintenance bill,” he says. The new equipment configuration has also reduced the company’s power costs by about 20%. “We used to calculate that if we ground material for an hour, then we would weld on our hammer mill for an hour.” He points out that the hammer mill’s infeed conveyor has a ballistics chute attachment that is designed to remove large tramp metal material out of the grinding. Two magnets downstream of the hammermill also minimize steel commingling with other materials.

Other equipment in the operation includes a two-stage WSM 72-15 disc screen from West Salem Machinery that provides final material sizing. Gillis notes that the screen was built to company specifications for its desired mulch particle size of 3-inch nominal. Oversized particles are taken off of the screen and conveyed back to the hammermill. “A disc screen has a free flow so air can flow up through it much more easily than I perceive an oscillating screen or vibratory screen can do, and we get really good pickup of material we don’t want in our wood product,” says Gillis. “I don’t ask my guys on the sort line to pick out that small plastic and stuff; I just say let it go and the equipment pulls it out.” Recovery1 also operates two non-blinding bivi-Tec screens from Aggregates Equipment Inc.: one for dirt and one for gypsum. An oscillating BM&M wood fiber screen and a trommel screen built by the company itself round out Recovery1’s equipment lineup.

Recovery1 primarily serves three markets with its wood products. For landscapers who sell mulch, the company operates a mulch colorizing system that dyes chips dark walnut, black, or red. Wood chips are used for fuel in plants such as paper mills and cement kilns. A major customer for wood pulp, Cascade Pacific Pulp of Halsey, OR, provides paper companies with recycled wood pulp. A future market for Recovery1’s wood products is particle board if and when local plants open in the company’s area.

Similarly, diversification is a key strategy at Shamrock Recycling & Transfer in Blaine, MN. In 2008, the company processed about 80,000 tons of various materials, including wood, concrete, cardboard, copper, aluminum, steel, alternative daily cover (ADC) for landfills, compost, concrete, cardboard, plastics, electronics, sheetrock, tires, and roof shingles. Uses for the wood include boiler fuel, landscape mulch, and animal bedding. Cardboard and paper are sent back to paper mills and turned into new products. Farmers use ground-up sheetrock to replace nutrients in soil, although regulators recently have begun to closely scrutinize the potential for wet sheetrock material to release hydrogen sulfide gas, which can be toxic at high concentrations.

Rich Gersdorf, co-owner, founded the company with his wife Becky in 2003 as a natural extension of a hauling company that faced high landfill tipping fees. The company receives materials from its own roll-offs and from other haulers, contractors, and the public.

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Commingled material is dumped at the front of the 20,000-square-foot facility and weighed before a front-end loader stockpiles the material for an excavator. The excavator feeds a hopper on a Continental Biomass Industries Annihilator shredding machine that sizes material for a sorting line. The shredder has a 6-inch forged steel, 20,000-pound rotor with reversible tips and an 8,000-pound, hydraulically actuated anvil door with a remote-controlled, adjustable cutting gap. “[The shredder] just makes it into a size that you can work with,” says Gersdorf. “For example, a 12-foot two-by-six is hard to maneuver compared with four 3-foot pieces. We typically like to size material to 12 to 18 inches.”

Following primary reduction by the Annihilator, the material is conveyed to a sorting line, where 12–15 laborers separate large pieces into containers that feed concrete bins located down on the main level. The remaining smaller material undergoes metal removal via a magnet and particles smaller than 1 inch are screened out and used for ADC. On the main level, a front-end loader loads trucks that deliver the larger pieces to customers that sell scrap material or manufacture recycled products. Next Page >

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