It Can Be A Grind

What do roadside brush removal, landscaping services, disaster cleanup, a new skyscraper, and Christmas trees have in common? They fall into that category of producing wood waste—and a lot of it. From pallets to pine trees, it all has to go somewhere and today’s technologies can efficiently grind, chop, or burn it to a manageable size, relieving the headache of landfill disposal. And, according to the manufacturers, today’s machines are tougher, greener, and more efficient than ever to handle this enormous task, and can even pay for themselves with a commodity output.

According to Matt Eul, senior product marketing specialist for Recycling and Forestry at Vermeer, “Grinders are one of the most important machines for any wood waste facility,” but he adds that “the type and size of a grinder is dependent on the type of material accepted, the size of the facility, and the amount of space they have.”

When land space is no limitation, “Tub grinders, like the Vermeer TG 7000 that are gravity fed, are a great option for wood waste facilities with larger yards that must process a lot of loose, green waste. These give the operator access to the entire mill table when performing maintenance, but you need to establish a thrown object perimeter all the way around the machine to properly set up a tub grinder,” explains Eul.

For facilities with limited space, he says a horizontal grinder might be the better option as “these machines don’t require as much open space and the open-end feed design of horizontal grinders efficiently handles larger wood material.”

Eul says the toughest job facing wood waste handling is “when the material being processed has a lot of contaminants like metal, plastic, and other foreign objects.” To help manage this and prevent machinery damage, Vermeer introduced the Damage Defense system for tub and horizontal grinders.

“The hammermill is the vulnerable component and is damaged by contaminants so when the mill comes in contact with these metals while grinding, the Defense System activates.”

He explains that the grinder control is alerted and automatically initiates a shutdown process by first idling the engine, then reversing the infeed or tub, and disengaging the clutch. When the contaminant is cleared away, the normal operations can resume.

When choosing equipment to perform wood waste disposal, Eul cites that having an equipment partner like Vermeer “who has responsive service and parts is crucial to maintaining optimum operations in grinding.”

Road Waste and Maybe a Few Tires

The transfer station in Cherokee, NC, replaced its old shredder with the new Hogzilla Tub grinder to tackle the disposal needs for the 15,000 Cherokee reservation members located west of Asheville, in the Great Smoky Mountains.

“We own about 57,000 acres and we had been looking for another shredder to replace our old one for some time. I had had several companies come out to demo the latest shredders and grinders and the tub grinder option seemed the perfect solution for us.”

Long says he talked with Tim Wenger of CW Mill Equipment Company that manufactures the HogZilla, who then assisted them in choosing the right unit to both meet the volume need of Cherokee, and to produce four composting products from the waste material.

HogZilla’s Tim Wenger, the vice president of sales, says that they began making their machines in the 1980s to divert wood waste from landfills “who were looking for a new option to wood waste disposal.

“A large percentage of our grinder machine operators process the wood waste for the landscaping market. The type of material you buy at the DIY stores has typically gone through a horizontal tub or hammer mill, and depending on how you process the wood waste you can get a shredded look for mulch, or if it’s chipped, it can be reground as a playground mulch.”

While the machines can be portable and run by diesel fuel in the field during debris removal, forestry operation, or on a construction project, the municipal customers who install these on a permanent site “can use electricity to run the machine which has a smaller carbon footprint over diesel.” He explains how the process works.

“When wood comes in, and this can be stumps, pallets, or other wood waste, it goes through a primary screen that has six-inch spacings. This reduces it to a smaller size that can be burned for fuel, or sometimes a company will come in and take it and reprocess the material, which keeps it out of the landfill. Or, the city can put it through a smaller screen and regrind it and then use this product to make sewage sludge as a bulking agent, or it can be used for inlet filtration products.”

Wenger says that their three HogZilla models are exceptionally heavy-duty with robust torque converters engineered to stand up to the toughest grinding challenges.

Protecting Your Investment
“Providing a solution to managing and processing the disposal of green waste is the stock in trade of the Rotochopper B66 horizontal grinder,” says the director of customer service, Doug Meyer, who shared that the company provides grinding equipment that specializes in “converting waste into profit, which can be biofuel, compost, animal bedding, and colored landscape mulch.”

“Our machines range anywhere from 200 horsepower to 1000 horsepower and feature a powerfeed opening up to 38 inches high and 66 inches wide, allowing them to accommodate a wide variety of municipal green waste including brush, pallets, and even large trees. In addition to the production capacity, the differentiation of the B66 comes with the options that are available on the grinder that will save you time and, more importantly, protect your grinder during operation.”

Meyer says that inevitably, non-wood material finds its way into the process at one point or another. But with the B66, what might end up as a major mechanical failure “when you hit steel or another contaminant that gets mixed in the wood waste” is a failure averted with their grinders. “Our patented stopwatch system detects impact and stops the grinder.”

With this system, he explains that there is ongoing monitoring of the rotor vibration, and knowing what type of sound deviates from the normal “harmonic amplitude” will set off the warning. “In other words, a properly functioning rotor gives off a certain sound, and if that sound—that harmonic wave pattern—changes and deviates from what we know to be normal, it sets off an alarm to the grinder.”

Another protective mechanism that Meyer describes is the Rotochopper Rotolink System that communicates machine performance from its onsite location to anywhere in the world via a modem.

“This is a two-way connection that both allows us to dial into the system and see on our display a duplicate of the display occurring on the machine, and it can send us a message to alert of any discrepancies in the data that the system is monitoring.

“Then, from our own computer we can adjust settings, see the health of the machine, the vibration frequencies, and the bearing temperatures. This is a terrific tool for management as well as the operators utilizing the machine.” Not only does the Rotolink System provide the ability to troubleshoot and work on machines in real time, but the system also provides a tremendous ability to monitor patterns and data over time. This becomes critical when looking at predictive modeling and proactive insights, which allow owners to capitalize on the overall efficiency of the machine at all times.

Meyer reports that the B66 can handle up to 400 yards of wood waste and tree waste in one hour. “We are the only machine that can take in raw wood waste and output it as a colored mulch in one pass that is suitable for bagging and commercial sales. The fact that the B66 grinds, sizes, and colors literally all in one pass is a tremendous benefit for businesses or municipalities who can derive a revenue stream from the process.

“And because the Rotolink system will instantly message the mechanical warning in real time to the operations manager, who is almost always monitoring the displays, there is instant troubleshooting with minimal downtime for busy facilities,” says Meyer.

“By processing and selling this recycled product as a composting material, or for commercial mulch and even animal bedding, the machine will pay for itself and moreover will keep wood out of the landfill.”

Success in a Closed System
The lightbulb of ingenuity can strike at any moment and may be precipitated by the most unlikely events. For Matt O’Connor, co-founder of ROI, and partner/CEO Anders Ragnarsson, “It was standing at a landfill watching the burning of wood waste and the ash being hauled off,” says O’Connor.

“As we watched this, we thought, there is something we can do about this,” he recalls.

“Both Anders and I grew up on dairy farms and were well-versed in the concept that Mother Nature will give to you if you give back. Burning wood just to get rid of it is a huge waste of energy and certainly not environmentally friendly, but making the burning process a closed system that is green and self-sustaining and produces a desirable commodity is almost too good to be true.”

But their line of Envirosaver carbonizers does all that and more. Developed both as mobile and stationary units, O’Connor says these machines “are the most environment-friendly wood debris conversion systems that take wood debris and other biomass and turn it into high-quality biochar,” a valuable product whose uses range from cosmetics to compost, he says.

He reports that their track-mounted Envirosaver 350 carbonizing system is powered by a Cat Acert diesel, weighs nearly 70,000 pounds, and is capable of processing 15 tons of wood waste an hour. At the end of the cycle, that original volume comes out as char “and represents 5–7% of the original volume.” So in other words, imagine a 32-inch-wide and 9-foot-long log weighing at least a ton, reduced to 150 pounds of biochar, about the same volume and weight as three large bags of garden soil.

O’Connor explains that after it is first ignited, the closed combustion system uses its own material as the fuel source.

“The primary combustion chamber is filled with wood waste and beneath that is an elevated grate where we introduce a preheated under-air. This increases the efficiency of combustion and eliminates inefficiencies from burning just from the top.

“As the flames are sealed in by an air curtain, the temperatures increase in the base material in excess of 2500°F. Then, this is where the paralysis process, as we call it, occurs. In this oxygen-starved area, the char falls off the parent material and into the grate below and the char collection pan. Then the char is augered to the rear of the machine where it is quenched, then conveyed to where the metals are separated out by a magnetic head pulley. Finally, it’s ready for offloading into whatever you have—a 200-yard trailer, for example.”

He says that while the burning takes place, there is an “over-chamber curtain of air that seals the top, keeping smoke and particulate matter from escaping.

“This air is projected at a high velocity across the top of the chamber and does not deflect off but is projected to the opposite wall.”

The ROI units are “the first truly portable burning unit that can realistically handle large volumes of unprocessed material including stumps, branches, limbs, two-by-fours, and leaves.”

Noting that the typical reaction to burning wood is unfavorable, “and carries the perception [that] it is very contaminating, with our machine there is virtually no escape of emissions and our carbon footprint is about the same or less than simply grinding, but we have this fabulous biochar commodity at the end. And with grinding you still have the waste, it’s just a smaller volume.”

O’Connor is enthusiastic about the Envirosaver paralysis process and its activated charcoal end product.

“This carbonizing process delivers a very useful commodity with so many potential uses. You can use it in any kind of filtration, from water to air; it’s also a great deodorizer, and as it’s 85% pure carbon it works superbly as a soil additive pulling in nitrogen and microbes to help to balance the soil.”

And Jason Feagans, owner of Blackwood Solutions, says he is equally enthused about the ROI having recently purchased the ROI Carbonizer 800.

“We’re in the wood recycling business and we have customers to chase the best options all the time. The Envirosaver is both cost-competitive and sustainable for landfill operations.

Innovation to Outperform
In 1988, the engineers at Continental Biomass Industries (CBI), a brand of Terex, got together with the idea “to build a superior land clearing wood waste grinding machine that would surpass all others,” says Joe Gallagher, spokesperson for the New Hampshire-based manufacturer.

“Our proposition is to outperform the real world of grinding.” And according to Gallagher, once customers use the 6800CT horizontal grinder, they never look back.

“In fact, our first machine put into service in 1991 is still in service today with more than 60,000 hours. Customers can select a CBI machine that’s just right for them, based on what the input is and what they want for the end product.”

Screen size and tips of the grinder are dictated by what’s going in, he says. For example, “Railroad ties which are highly contaminated would not be repurposed the same as forestry logs, or storm debris and pallets.

“A lot of times there is an end-use market already set up; for example, the cleared wood and debris from forestry operations can, after processing, go directly to landscape suppliers. Customers can explore income opportunities and develop these markets as their grinding business grows.”

Both stationary and portable machines are offered; he says the CBI Magnum Force 6800CT Horizontal Grinder has a 15% larger screen that wraps 190 degrees around the rotor.

“This offset helix rotor has 20 welded hammers that distribute the wear across its surface as it grinds, and is powered by a 1200-horsepower Cat engine and is so robust you can process more than 200 tons an hour from just about anything you can imagine—land cleaning debris to shingles to whole trees. And operators can adjust the feed speed, its pressures, and automated control systems,” says Gallagher.

He adds that their sophisticated metal detection system (MDS) uses the harmonic frequency of metal strikes to alert the machine to shut down. “Depending on your application, you can set the MDS for different values, and you can detect a little sandwich bag of bolts, a hammer, and more. Once we had a ball trailer hitch come through and it was immediately picked up; the machine went into a shutdown mode so there was zero damage on what could potentially have been tens of thousands of dollars in repair.”

Citing maintenance time as minimal, Gallagher says keeping everything sharp helps operators reduce any downtime. “The feed box can easily raise and lower, and this allows a changing of the teeth tips on the screen; when those are kept at optimum performance there is less wear on the grinder itself.”

Gallagher adds that they became a Terex brand in 2015; “What this brings to the end-user is the best horizontal grinders in the market through the established distribution channels of Terex.”

Powering Up Your Site
The genesis of new technology is very often shaped while facing an existing problem and Norbert Fuhrmann, vice president of Florida-based Air Burners, says their company was founded on that very principle.

“The first of our technologies were originally developed in the 1970s and designed to overcome the menace of open-air burning. We knew there had to be a better way to dispose of wood waste, using a burning technique. However, while we didn’t build it with the intent to reduce wood smoke, or pollutants, in fact, the first air curtain Air Burners did do this. As we’ve advanced our technology, and with increased concern over air emissions, it was the right unit at the right time, and today is better than ever. “

Fuhrmann says that line of five wood waste burning units, both stationary and portable, makes the term “air-burning” a reality.

“We’ve been perfecting the original concept of a firebox—but one raised off the ground whose combustion is contained and also maintained by an overpassing air curtain.”

He explains that a high velocity of air passes over the top of the firebox: “The purpose is to create a curtain, like a lid, over the machine. This controls the smoke and pollution that would otherwise be escaping into the environment. We direct oxygen into the box to make it efficient burning, so during combustion, there is only the release of CO2 and water, no smoke at all.

But, he adds, this is biogenic CO2, which is defined as an emission from an organic product, not a fossil fuel, so it is considered carbon neutral and not harmful.

Fuhrman says that engineering is very specific to create the perfect firebox opening and an air mass velocity that is going to kick back the particles. Perfecting the balance of just the right amount of air to reduce the waste to CO2 and water vapor was their engineering design goal. And it is also one that can pass the rigorous muster of EPA permitting requirements when used as a stationary unit.

“Our latest innovation is the PGFireBox; that is the first portable unit to generate power from unprocessed biomass, and is available in 100-kilowatt, 500-kilowatt, and 1-megawatt power range. With this series, the forestry market and landfills have a perfect solution to meet their needs in processing vegetative waste.”

Explaining that the energy value from wood can and should be captured, “not buried in a landfill,” the PGFireBox air curtain burning process makes short work of huge jobs.

“This machine reduces wood waste onsite by 98% with only a few pounds of ash as the output from 10 tons of logs. There is no need to transport your waste somewhere else, or pre-grind that waste. You can set up the PGFireBox, and based on what your market volume and needs are, you can throw in whole logs, pallets, rootballs, and whole crates. Then, by capturing the energy from these wastes, your site can convert it into electricity that can power your operation, or be sold as a revenue source. You also don’t need any additional fuel source like natural gas—it truly is a self-contained, one-stop shopping operation.”

Furhmann adds that there is a pressing need to both clean the forestry waste from recent wildfires and clear other areas to prevent wildfires. State and local governments can install a PGFireBox and tackle these jobs, perform onsite burning for 5–8 years in one location, and “Then, when finished, simply disassemble the unit and move it to a new location as needed. It doesn’t take long for the units to pay for themselves, and they can make you money in the process and you can receive landfill diversion credits as well. You just tie into the high-tension lines and literally “fire away.