June 2012

Sustainable Shredding

As the focus on sustainability gains traction, markets for greenwaste materials continue to grow.

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Grinders and shredders in North American MSW operations are generating revenues through the creation of everything from landscape mulch to waste-to-energy fuel, as the latter market takes an increasing foothold in the United States.

More than a year ago, Lindner Recyclingtech set up a subsidiary in Raleigh, NC, to address the emerging refuse-derived fuel (RDF) market in the United States.

The company’s primary focus is the RDF market, notes Andreas Schwartz, company president.

In Europe, Schwartz says, “we have more business than we know what to do with because the RDF market there is very hot.”

While the RDF market finds its place in North America, Brad Van Rheenan, application specialist with the environmental group for Vermeer, says grinding for landscape mulch might be the biggest market, with colored mulch in demand.

Monte Hight, Rotochopper sales and marketing manager, agrees, saying landscape mulch is one of the most profitable products derived from grinding and shredding operations.

Hight says some companies are sorting material down to clean, untreated woodwaste and producing landscape mulch in regional markets where the demand exists, as well as the space to stockpile material until the mulch market begins in spring.

Colored or natural landscape mulch requires untreated wood. Such engineered wood products as oriented strand board and plywood are typically better suited for boiler fuel or for animal bedding instead of mulch, Hight adds.

In other cases, operations are opting for animal bedding markets to address the need to keep a steady flow of material coming in and going out, Hight says.

Vermeer’s end users tend to be landfill operations that take in and grind greenwaste, using either the horizontal or tub grinder, and will bury it, give it away, or sell it back to the community, as well as produce animal bedding, notes Van Rheenan.

“We have several municipalities that are running greenwaste at landfills,” says Diamond Z sales representative Jens Jensen. “The wood is brought into the landfill, then they’ll grind it and some will color it and either give it back or sell it back into the community.”

Diamond Z has optional equipment that colorizes mulch in a variety of colors, including red, black, green, and blue.

A broad spectrum of applications is employed by those who use equipment from eFactor3, which offers shredding, cleaning, granulating and extrusion equipment as well as conveying and separation equipment, systems integration, and installation.

“Our end users are producing refuse-derived fuel, processed engineered fuel, and fuel from C&D waste,” says company president Hartmut Bendfeldt.

Other applications of the company’s equipment include reducing the waste size for further processing in the landfill for better decomposing and compaction.

“We also have companies that recycle certain materials that go back into other products,” Bendfeldt adds.

Tim Wenger, president of CW Mill Equipment Co., notes there are several typical customers for HogZilla grinders, including land-clearing contractors who, restricted by anti-burning bans, grind the material to use onsite or as a fuel source for a boiler.

Others produce mulch from material collected from job sites or wood debris from urban areas and grind the material for compost or colorize it for mulch.

Municipalities with greenwaste facilities also use the technology, taking in material—sometimes for a tipping fee—to grind it for compost, sell it for fuel or sometimes give the material away to the public, Wenger says.

Other customers grind rubber tires, mixing the ground-up rubber with coal or wood for fuel, Wenger says.

“A lot of times, wet wood doesn’t burn so well, so they mix the rubber with the wood to burn it,” he adds.

Or they grind plastic, also burning it with coal and wood, obtaining “green credits”  for doing so, Wenger says.

“It’s become somewhat of a lucrative activity,” Wenger says. “We recently had a customer who was grinding tubs of butter that had gone bad, mixing that with wood and running it through a power plant. They get green credits from the government for burning this type of material.

“Rather than take that material out to the landfill, they’re able to grind it, mix it with wood, burn it and receive a pretty good tipping fee for taking the material,” he adds. “They’re able to utilize the BTUs in their boiler in addition to the wood that they’re burning.”

Most RDF producers require enough machine power to meet the demands of boilers and may have more than one machine to meet those needs, Schwartz says.

“The plants that consume that fuel need at least 10 tons an hour of production,” he says. “That’s why most people operate with one or two big shredders. Ten to 15 tons an hour is the normal application for one big shredder.”

Lindner Recyclingtech manufactures three types of single-shaft shredders.

Jupiter is a slow-running primary shredder used primarily for preshredding materials such as domestic, commercial and industrial waste.

Komet and Power Komet are robust shredders used primarily for secondary shredding/granulation of preshredded material free of large foreign parts, such as paper, cardboard, plastics, foam plastics, and rubber.

The universal shredders, Universo, Micromat, and Vega, are slow-running shredders.

Lindner’s smallest shredder is the Vega, which is used only for plastics recycling and handles 400 to 1,500 pounds an hour, says Schwartz.

Next in line, the Micromat starts at 3,000 to 5,000 pounds of plastic recycling an hour. Above that is the Universal, which comes in various horsepower ratings.

“It can be a secondary shredder for plastic recycling or it can be a primary shredder for municipal waste,” says Schwartz. “If somebody only needs 10,000 pounds an hour of primary shredding, then the Universal would be fine.”

Within its product line, Bandit Industries manufactures horizontal grinders through the Beast series. The average yards per hour processed by the machines include 150 for the 1680 Beast, 300 for the 2680 Beast, 500 for the 3680 Beast, and 800 for the 4680 Beast. The size most used in the landfill and municipal waste industry is the 700 horsepower 3680 machine, notes Chad Florian, Bandit’s regional sales manager.

“Depending on the waste they are grinding, it could end being mulch, compost, or even sent to landfills but in a much smaller product size so it takes less space and decomposes quicker,” he says.

CW Mill Equipment manufactures 14 standard HogZilla models ranging from midsize to large units, including self-propelled track-driven and self-loading units.

The TC models use a torque converter to drive the adjustable hammer mill. The HC series grinders feature a hydraulic coupling or optional torque converter, and the WC series is designed to offer the features of the other models in a smaller package. CW Mill also makes a track-mounted HogZilla tub grinder.

With the cost of diesel fuel increasing, the company’s electric-powered grinders have become more popular for their increased efficiency and reduced maintenance needs, says Wenger.

CW Mill’s TCII-1564 is the company’s heaviest-duty machine and most utilized by the waste industry because of the uncertainty of what’s included in the wastestream, such as concrete, metal, or rock, Wenger notes.

“Customers prefer spending extra to have a heavy-duty machine that can encounter some of these surprises without destroying the machine any worse than possible,” he says.

The smaller machines are typically used for mulch operations or municipalities that have a measure of certainty about the waste, such as greenwaste.

CW Mill runs costs-per-ton analyses on various material types, but Wenger points out that it is dependent upon the incoming material and the desired finished product.

“It also depends on the amount of dirt, sand, and whatever else is in the material—the abrasiveness of the products used in the grinder,” he says, adding that those factors will influence the wear and tear on the hammer tip and screens.

Additionally, “smaller desired products reduce production substantially,” Wenger notes. “The bigger machine, the bigger the horsepower.”

Some operations try to save money by purchasing a smaller, less expensive grinder than their operation essentially needs, Wenger says, adding that a smaller grinder may create a “false economy” in that the machine doesn’t hold up to new production in a reliable fashion.

“A customer just starting out by buying a used large grinder such as ours would have a better investment than buying a smaller, newer grinder in the sense that the large material they’re trying to grind may potentially have metal in it,” he says. “The smaller, cheaper grinder may end up costing them many times more on account of that metal than buying a heavier-duty used machine.

“It’s always best to buy the biggest machine you can afford,” he adds. “Nobody really regrets buying too large of a grinder.”

The mixed nature of the material makes separation for reuse or diversion a challenge, says Sean Grieve, business development manager for Doppstadt US.

Rising fuel costs also affect the trucking expenses associated with transportation of MSW to landfills, he adds.

“Doppstadt US offers portable or stationary sorting systems to help enable separation and recovery of the desired materials,” Grieve says. “The Doppstadt range of portable and stationary electric shredders can help to ensure trucks are moving from transfer stations to landfills with load weights that are closer to ideal.

“The shredders typically reduce the volume of MSW by about 30%, and that can add up to significant fuel savings. Their ability to reduce the oversize bulky waste for further processing through a system is an additional benefit of the shredder range.”

Common outlets for processed MSW include the fuel and waste-to-energy market, Grieve notes.

“That’s likely to feature prominently in the future,” he adds.

Rotochopper makes a line of diesel and electric horizontal grinders, wood chip processors, asphalt shingle grinders, and mobile bagging systems.

Models in the diesel horizontal grinder line range from the compact MP-2 2 with 275 horsepower to a B66 with up to 875 horsepower, and include a mid-sized model, the MC-266 with 475 horsepower.

All of the horizontal grinders can be equipped with a grind-and-color system for creating colored mulch in a single pass (standard on the MP-2). Rotochopper has a bale processing system designed for efficient processing of square or round bales.

Electric grinders are used for sorted C&D, sawmill waste, foodwaste, MSW, and other applications with steady raw material streams.

Rotochopper works with companies that recycle paper, cardboard, wood, and asphalt shingles sorted from C&D waste. The company also works with municipalities that convert municipal yardwaste into compost.

“We provide electric grinders that are used in sorting systems where they’re taking mixed wastestreams and sorting it down to clean wood,” says Hight.

The choice between electric and diesel comes down to whether there is a need for mobility.

If so, diesel is the machine of choice. If not—and a company has access to three-phase electricity—the electric models offer substantial cost savings, Hight notes.

In terms of equipment sizing, “we typically look at the volume of material and try to take into account ways in which that volume might grow or stay the same,” says Hight.

“We look at the feeding methods used to load the material into the grinder—if it’s going to be something off of a sorting system where it’s more or less a steady stream coming directly out of a conveyor or if they’re going to be batch-feeding the machine with a front-end loader or excavator.”

Those working with a steady stream often choose the least amount of horsepower so the equipment is operating as efficiently as possible without wasting a lot of horsepower during the grinding process, Hight says.

“If they’re going to be stockpiling material and batch feeding it with a loader or an excavator, there might be a range of horsepower that might work depending on how much they need per hour,” he adds.

As for operation and maintenance costs associated with the equipment, “given the complexity of any recycling market, O&M costs can be significantly different based on differences in feedstock consistency,” says Hight.

For instance, throughput can vary widely from municipal yardwaste to construction and demolition debris. Maintenance costs can vary as well, given varying levels of abrasiveness of feed materials. The price of a grinder can swing with the choice of options.

In helping customers find the right machine, “the place we start with customers is to look at markets for their finished products: compost, boiler fuel, landscape mulch, for example,” Hight says. “Then we look at the volume of raw material and guide the customer toward the right size of machine.”

The economics are determined by the market value of the finished product minus the O&M costs, plus any applicable transportation costs, Hight says.

“Some municipal waste handlers might want to grind material simply for the sake of disposing of it more cheaply,” Hight says. “In most cases, however, the types of materials that can be processed with a grinder can and should have a profitable end market.”

Vermeer offers horizontal grinders and tub grinders and recently introduced a whole-tree chipper into the marketplace. The company also offers drum and elevating face composting equipment and trommel screens.

The grinders feature optional-length feed tables. The thrown-object deflectors reduce the quantity and distance of thrown material.

Vermeer horizontal grinders feature remote-controlled operation, the SmartGrind feed system that automatically controls grinding speed based on engine rpm levels and the Vermeer Duplex Drum.

Equipment size depends on the type of production and is sized to whatever other equipment is in the fleet, Van Rheenan says.

“You would want it to be sized proportionately so you can get the most use out of your dollar,” he says, adding most municipal operations opt for midrange horizontal grinders, while private contractors will purchase larger machines.

Van Rheenan says it’s difficult to ascertain how much throughput is needed to justify purchasing different classes and sizes of machines because of the inherent variables.

“The type of material you’re putting in is a huge variance, and the size of the product you want coming out of the other end affects that greatly,” Van Rheenan says. “It depends on what size stream you put into the machine.”

Diamond Z offers horizontal, tub, enclosed, tire, and solid waste grinders. Horizontal grinders comprise 70% of the company’s sales.

“People are making a move toward horizontal grinders because they’re versatile,” says Jensen. “We still sell tub grinders and sold quite a bit when we first started building tub grinders. But now the majority is horizontal.”

Maintenance is critical, Jensen says.

“Machines are going to have their issues, and the best thing you can do is preventive maintenance, to stay out front with your bearings and go through startup procedures regularly,” he says. “A good maintenance program reduces downtime.”

Markets for the end product are more about the material going in than what is coming out, Jensen says, adding that many operations use his company’s grinders for colored mulch and boiler fuels.

“If you take just brush and leaves, you’re not going to get chips,” he says. “If you have logs going in, you tend to have longer length material, and the horizontal grinder is better. If you have stumps, chunky wood, and uneven size material, then the tub grinder is really good. A lot of it is screen selection to size your product or chipper conversions. Most everyone has a conversion to get the chips from the big wood.”

There are many variables in determining a price per ton, Jensen says.

“If you’re just blowing things through a larger opening, a 7-by-9-inch opening screen versus a 2-inch or a 1-inch opening screen, you’re not going to get the production,” he says. “There are so many factors, like moisture content, fuel consumption and screen selection—bigger wood versus easier grinding pallets versus solid oak. It’s difficult to put a number on it.”

A rule of thumb in baseline input is to get a machine that’s 20% larger than current needs to allow for expansion, Jensen says.

“You hate to buy a machine that will barely cover what you’re doing and as your in-feed stream increases, then you’re behind the eight ball,” he says. “Generally, you try to get out in front of that. That gives you room for expansion.”

Untha America pioneered the four-shaft shredder technology and continues to make a variety of small four-shaft shredders, says Peter Dion, regional sales manager for Untha America.

The company makes a range of pre- and post-shredders for making RDF.

“Processing MSW into fuel is one of the areas of focus of the last eight years in terms of revolutionizing what a pre- and post-shredder does and how it does it,” Dion says.

Untha’s XR series is a preshredder/primary shredder developed for shredding municipal solid waste, bulky waste, and commercial solid waste, and is primarily used for producing coarse and medium fractions.

The preshredder’s cutting system features a predefined particle size and is designed for high resistance to foreign matter and low operation costs.

“It takes raw MSW down to 6- or 8-inch chunks, and then you would remove undesirable material with wind shifters, air knives, magnets, eddy currents, or some of the newer optical sorting systems,” says Dion.

The leftover material would go into the TR series post-shredder, taking it down to the 1-inch-plus range.

Untha’s managers have spent a lot of time speaking with end users of MSW shredders in Europe to find out what worked and did not work.

“That turned into the TR series post-shredder,” Dion says.

That shredder was designed for the post-shredding of the high calorific fraction and is primarily used in preparation of secondary fuels, such as RDF, solid recovered fuel/specified recovered fuel, or fluff.

“It’s a revolutionary machine in that it doesn’t use any hydraulics,” says Dion. “The RS series four-shaft shredders can be used for wood, light metals, tires—things of that nature. You use a four-shaft shredder when you want to achieve a specific particle size for separation or densification.”

MSW operations typically use single-shaft shredders, such as the company’s XR and TR series, Dion says.

The XR series can process 35 to 40 tons maximum, while the TR series does about 15 tons an hour, Dion says.

“The reason it’s so much less is you’re going to a smaller size and you have a net of material because you’ve done that material separation between the XR and the TR series,” he adds.

Untha has changed the control systems in the past few years.

“There are ways you can speed them up, slow them down,” Dion says. “We’ve got a new system where the post-shredder can monitor what’s happening with the preshredder, and adjustments can be made accordingly in terms of getting an even flow of material through.

“You can monitor it, look at trends over time and have a pretty good idea as to what’s happening to your cutting system in terms of wear because you can watch what’s happening with the current draw and how long it’s taking and if you’re sampling, figure out how many tons you’re putting out, how much current you’re using.”

Determining a baseline throughput to justify the choice of a machine depends on customer specifications, Dion says.

“If you’re doing metals, you’re not going to be buying a single-shafter,” he points out. “If you’re doing wood and plastics, your choice is a little bit greater. If you’re going to do landscape mulch, you know you’re going to use a single-shafter. Then you start looking at what you’re going to put in it terms of size. Is it pallets? Is it driveway waste? Is it some sort of other production waste? That will dictate what you’re going to use for a machine, and if you look at things like mulch, where do I think I’m going to be in five years?”

Dion suggest looking at other operations, if possible.

“A lot of times it’s not necessarily what they tell you; it’s also what you see,” he says.

Dion had visited a plant that was processing shredded paper, such as catalogs.

“First thing I notice is there’s a shredder sitting there,” he says. “Right next to it is a ladder and next to that was an 8-foot long piece of two-by-four, and next to that was a garden hoe with an extension on the handle that was duct-taped onto another small piece of wood.”

Dion says because the plant had not chosen a shredder appropriate to its operation, an employee was staged on a ladder next to the shredder. The plant was processing light, “fluffy” paper.

“A single-shaft shredder doesn’t do very well with light, fluffy paper, so it would flop around, and he had to hold it down so it would shred,” says Dion. “If it really got into problems with a lot of piles of dense paper riding on top of the ram, he would use this hoe to push it down.

“That was due to making the choice of a shredder based on price—the cheapest thing he could find—and not looking at what it costs the company to have a guy stand on a ladder, looking over the hopper of a shredder.”

SSI Shredding Systems offers the Uni-Shear, a medium-speed, single-shaft, rotary shredder/grinder recommended for wood, paper, hard plastics, and other brittle materials with limited metal contamination where small, uniform particle size is important. It can be configured with electric or hydraulic power options.

SSI also produces the Dual-Shear, a low-speed, high-torque, two-shaft rotary shear shredder recommended for metals, soft plastics, tires, product destruction, or any diverse and contaminated materials where particle size variation is acceptable. It is configured in a variety of sizes, drive options, and cutter configurations.

The Quad is another of SSI’s shredders, a low-speed, high-torque, four-shaft model suited for such applications as electronic scrap, tire recycling, alternative fuel production, and reduction of contaminated materials where uniform, small to medium particle size is desired. It can be configured in a variety of sizes, power options, and cutter geometries.

And SSI’s line includes the Pri-Max, a low-speed, high-torque, multimaterial primary reducer, with high capacity for C&D debris and for volume reduction of solid wastes containing metal and abrasives. Particle size is coarse. It can be configured in a variety of sizes as mobile or stationary units and with either electric or diesel power options. The Pri-Max Primary Reducers process between one and 150 tons per hour while achieving up to 80% volume reduction. The cutting table’s heavy-duty, open-grate design allows fines such as rock and dirt to fall through, reducing wear on the cutters.

“Because we’re application-driven, the choice of equipment can vary based on the customer’s requirements,” says Joby Easton, director of sales and marketing. “In some applications, it might be a primary waste reducer. In some, it might be a series of Dual-Shears, because shredding at its core has three key components: the application, the throughput, and the output.”

Among the product offerings from eFactor3 are Metso preshredding fixed equipment.

The size chosen by end users depends on the application and can range from the Metso 1000S for smaller applications to the Metso 6000S, a twin-shaft shredder. One of the most preferred models among end users is the middle-of-the-road 4000S twin-shaft shredder model, Bendfeldt notes.

“The driving factor is primarily the capacity people are looking for,” he says. “Many applications range somewhere in the range from 30 to 100 tons and this machine has an opening that is 8 feet by 8 feet, so it gives a good capacity and makes the machine very versatile.”

How much a machine can process depends on the waste composition, Bendfeldt says.

“It’s different when you’re talking about MSW or C&D waste,” he says. “The other question is what is the requirement of the further processing—if you’re looking at 4 inches minus, it takes longer to run it through the machine than if you want to get it done to just to a foot and a half.”

Bendfeldt says the Metso’s open cutting table offers larger shredding capacity and less wear, with O&M costs being minimized through preventative maintenance. The machines shred in both rotational directions. Mobile configurations are also available with most of the models.

Shred-Tech manufactures a line of two-shaft and four-shaft shredders.

“All of ours fall into the area of slow-speed, high-torque, shear shredders,” says Sean Richter, senior technical sales representative for the company.

The ST Series’ dual-shaft shredders range from 10 horsepower (7.5 kW) to 1,200 horsepower (900 kW) and are available with electric or hydraulic drive configurations and either stationary or mobile configurations and are designed to shred anything from “tires to
tea bags.”

“It depends on the application or if you require a certain amount of cutting force or the ability to absorb shock loads with the hydraulics,” Richter says.

The STQ series four-shaft shredders are designed to process such bulk materials as wood, plastics, paper, tires, textiles, electronic equipment, and manufactured products to a uniform particle size in a single pass.

The shredders have interchangeable screen sizes to allow for flexibility in particle size, with models ranging from 40 horsepower (30 kW) to 200 horsepower (150 kW), available in several sizes of cutting chambers.

The MSW sector uses the company’s shredders primarily in waste-to-energy applications, Richter notes.

Richter’s rule of thumb for a baseline throughput to justify machine choices is the tons per hour and, after that, shred size.

“The smaller you want to go, the higher the cost, the higher the wear factor, and the more complex the machine size becomes,” he says. “Keeping the shred size as large as possible also makes separation a lot easier on the back end, too, when you have a lot of particles.”

The Peterson Pacific Corp. manufactures horizontal grinders from 550 horsepower to 1,200 horsepower, depending on the application. They come in both a wheel and a track version.

“We have a variety of screens or grates that we run after the machine to size the material to what the spec is,” says Michael Spreadbury, marketing manager for Peterson Pacific. “We’ve got large grates with a 6- or an 8-inch opening. We can go down to a 1- or a 2-inch, but that would typically be for a mulch application.”

For the MSW market, the company slows down the rotor and brings the RPM down, Spreadbury says.

“We’ve reinforced the mill with higher-strength steel,” he says. “We put in a different grate configuration to let contaminants pass easier.”

The North Memphis Landfill in Tennessee uses Peterson Pacific Corp.’s grinders on a daily basis for size reduction, Spreadbury says.

In California, MSW operations are sorting the waste, he adds.

“California has some very aggressive recycling initiatives,” he adds. “We’re seeing sorting stations where they are sorting everything—they’re getting all of the metal out, all of the construction debris out, and all of the yard debris is going into a different container. The yard debris is used for composting and mulching applications and/or doing size reduction as well.”

Spreadbury says in purchasing a grinder, MSW operations should aim for a machine that can accommodate at least 25% more than what is believed to be needed.

“Once you find out that you can do it, almost all operations will push it more,” he adds

Tons-per-hour production on the machines vary. For example, operators may be able to generate 425 cubic yards per hour for the middle-of-the-road 4710B track-mounted horizontal grinder with a 765-horsepower Caterpillar engine.

“It depends on what you’re trying to run through it, grate configuration, how small you want to make it, how good of an operator you have loading it, and what kind of contaminants you have in it—all of these things are going to come into play,” says Spreadbury.

The same is true for O&M costs per ton.

“It depends on size of material going in, the sizing grates, the operator, how much moisture is in it,” he adds.

Spreadbury notes a trend toward stationery electric machines, driven by fuel costs.

“A lot of these facilities are indoors because of odor abatement problems; you can’t run a diesel machine indoors,” he says. “In California, there is an increasing demand on emission controls, so we’re seeing electric machines, especially in the C&D applications. Because C&D operations typically don’t move machines a lot, they’re bringing the material in as opposed to going to a land clearing where they need tracks and have to go from pile to pile.”

DuraTech manufactures tub grinders, horizontal grinders and tree chippers for industrial use and tub grinders for the agricultural industry under the banner of Haybuster.

The main machines for the MSW market are from the DuraTech side, with some smaller operators using the Haybuster PTO-driven grinders for smaller volume projects, says Jamie Kramlich, sales coordinator for DuraTech Industries.

In choosing an appropriate grinder for industrial use, Kramlich first asks end users what kind of output they seek, followed by the desired volume and size of the product.

“My third question is cost; that’s a big issue,” he says. “Is their operation big enough? Are they looking for a great big volume? Are they going to be able to afford a rough figure half-million dollar machine to be part of their system in what they are doing? I usually ask those questions in that order to determine if a particular machine is going to work for them or not.”

By far, presorting is one of the most significant measures an MSW operation can take to minimize O&M costs, manufacturers say.

Many operators are reluctant to invest the manpower or the money to do that, Wenger notes.

Pulling out such undesirable materials as metals, mixed steels, and explosive materials from the wastestream prior to shredding can help minimize O&M costs, Richter points out.

Additionally, batch processing woods and plastics rather than doing mixed-stream shredding also helps, he adds.

“A lot of times, the back end is easier to handle if it’s a single-stream mixture,” Richter says.

Schwartz points out there are a number of factors that influence O&M costs on shredders.

“Power consumption is a significant cost because they tend to have a lot of horsepower,” he says. “There’s really not much you can do about that.”

The second largest expense is tooling.

“If you have highly abrasive material like sand or a lot of glass, the lives of these knives are a lot shorter,” Schwartz says.

Processing only clean material, a knife can run up to 300 hours before it needs to be rotated, Schwartz says. Processing highly abrasive material, however, can result in a knife that can run as little as 80 hours, he adds.

“There’s not a lot the operator can do about it other than not feed the machine high-abrasive material, but that’s not always a choice,” he says.

“People are mostly concerned about output on these machines,” Schwartz adds. “If you maintain the tools and change them at the appropriate time, you can maintain a decent output and the overall cost is lower. If you run the knife until it’s completely worn out, you can’t rotate them any more and, therefore, the cost is higher. You may have saved a couple of hours of work, but you’re spending more money on tooling, so proper tool change and adjustment is the only thing you can really do to optimize the tool life.”

Spreadbury agrees.

To minimize O&M costs, “the material should be staged properly before it’s put into the machine,” he says. “They want to have a way to get the material away from the conveyor because it’s not going to take long to reach the height of the conveyor. They need to have a good way of getting it in and out of there and keep that hopper full.

“They need to minimize contaminants. They need to make sure the machine is in good operating condition and has new bits and new grates to maintain properly because worn-out grates and worn-out bits will significantly cut down on production.”

Minimizing O&M costs is location dependent, Van Rheenan says.

“Trucking becomes a big cost. Some of these folks traveling to sell their product to biomass plants to burn it for fuel are saying 80 to 100 miles away from the plant is stretching it. They like to stay around 70 if they can,” he says.

Downtime due to a broken piece of equipment also adds to costs.

“You’ve got guys getting paid hourly, and they’re standing around waiting for the machine to be repaired,” Van Rheenan points out. “You have to keep maintenance up on the machine so you don’t experience downtime and try to work in such a way that you’re not trucking your material any further than you have to.”

To minimize O&M costs, Dion points out it’s important to monitor the wear on the cutter teeth and not wait too long to rotate them as well as doing other preventative maintenance.

“Your throughput is going to go down as the teeth wear, and if you wait too long it’s almost an exponential drop, and then what will happen is you’re spending a lot of electricity and not getting the throughput on it,” he says.

On every control box of each shredder, Untha puts stickers that read: “This equipment pays your salary—take care of it.”

“It’s little things like air filters and keeping up with the hydraulics on the XR,” Dion says. “We’d go into a plant and see the entire heat exchanger on the hydraulic system that keeps the oil cool is so full of dust it’s not doing anything.”

Kramlich points out it costs ‘X’ amount of dollars to run a grinder, no matter whether it’s grinding at full or half capacity.

“Obviously, you have to keep the grinder busy,” he adds. “This means plenty of support equipment and plenty of manpower. The bigger the grinder, the more support equipment you’re going to have. Other than that, it takes normal maintenance with oil changes and greasing, cleaning of the machine and following the guidelines to break the machine in.”

As for North America trailing Europe in the waste-to-fuel market, Schwartz points out that Europe’s efforts are supported by the European Union’s landfill directive that aims to minimize landfilling when feasible with a reduction of biodegradable waste to 35 percent of 1995 levels by 2016.

“Here, there’s more of an interest in landfill expansion,” says Schwartz. “The East Coast has a lot of landfills, but nobody wants to build a new one anymore because it’s more expensive than it used to be. People try to do RDF to expand the landfill. High power consumption companies can use it.”

Richter agrees.

“Here, the cost of landfilling in most places is more economical than putting in a shredder system with waste energy on the back end because they can cost upwards of a million dollars,” he says.

Presorting—a significant measure manufacturers recommend MSW operations take to minimize operation and maintenance (O&M) costs—is a standard practice in Europe, Dion points out.

“The philosophy in the United States is mostly mass burn, If you look at the kind of junk that comes through, it would destroy one of these machines,” he says. “Whereas in Europe, there’s a lot of presorting and there’s a lot more control over what gets into the MSW stream.”

During a recent visit to a waste facility, Dion observed items being dumped out on the tipping floor, such as small refrigerators and cylinder heads from engines.

“You can’t do this kind of shredding that is done in Europe to create high-quality fuel because you’re not cleaning up what’s going into it,” he says. “The economics for doing that are not here yet.

“These guys say they are getting so many bucks a ton to take this stuff, so basically they’re getting money for their fuel—they don’t care if it’s fully burned or not—and they’re making electricity and can sell the electricity and whatever metal they’ve got on the other end. It doesn’t work that way in Europe, and I think that has to be more controlled here.”

Europe is achieving “phenomenal throughputs,” Richter says. “We’re not to that stage yet. The demand in North America isn’t as strong as what’s happening in Europe. Everybody I talk to—especially in the landfills—say it’s still cheaper to put the stuff into the ground. That’s the problem. Until it gets to the point where it starts to make real economic sense, I don’t think we’re going to see the real growth.”

Acknowledging that grinding and shredding for waste-to-energy is a “very big and upcoming field” in the North American market, “I don’t think anybody knows how to do it correctly yet,” Richter says. “Until the models get here from Europe and are driven by the need to keep the stuff out of the landfill, it’s going to be a while longer.”

“There are probably a couple hundred projects out there for RDF; there aren’t too many people doing it yet,” Schwartz says. “There is lots of talk, but not that much action yet.”

Kramlich says the biomass fuel market is growing, but has inherent problems.

“Nobody has found an efficient way to take a low-cost product, whether it be woodwaste, switchgrass, or corn stover, and grind it fine enough to either palletize it or direct-inject it to a furnace,” he says.

It will take an electric-powered grinder to derive those efficiencies, he adds.

“The input cost is a big factor that makes this not cost-efficient,” Kramlich says. “Most of these guys really need a fine grind and what they have to do to get that is have a primary grind and a secondary grind. You have double the input right off the bat because you’ve got to run it through twice. You not only have the cost of grinding itself, you have support equipment and manpower hours that add to the cost of it.

“They’re looking for high volume with one grind,” he adds. “An electric powered grinder is going to be more efficient if you can get electric power reasonable.”

Van Rheenan says a lot of operations want to engage in fuel production, “but they don’t have the facility in their area to sell to.

“It’s what comes first, the chicken-or-the-egg-type thing,” he adds. “Plants want there to be loggers in the area that will produce biomass so they can build a plant. Obviously, the loggers aren’t going to buy all of this equipment and get geared up to do it unless there’s a plant to sell it to.

Easton agrees with others in the industry that while “waste-to-energy is a factor and biomass is an opportunity, it’s still early in the game here in North America. In Europe and parts of Asia, because of the density of the people, the limit of resources, and the finiteness of property, everything is so much more dense. They put much more of a premium in the recycling process.

“I’m seeing the trends as commodities become more critical and the challenges that are built in to extracting resources from there become increasingly difficult—you have to go deeper, go wider. You have more environmental regulation; you have more ‘not in my backyard’ to harvest or claim something from the earth. In general, I think that leads into recycling becoming more valuable.”

Author's Bio: Carol Brzozowski specializes in topics related to stormwater and technology.