Wood Grinders by Mark Henricks

Any product that makes small problems of big problems gets a warm welcome from recyclers. Assisted by rising interest in biomass and waste-as-fuel, manufacturers of wood and green waste grinders are seeing good demand for their products.

Wood grinders come in two main versions, a gravity-fed tub design or the increasingly popular horizontal grinder. Horizontal grinders appeal partly because of safety. They are seen as less likely to accidentally throw material out, presenting a hazard to operators, than gravity-fed tub grinders. This is particularly important in recycling yards and landfills where there may be more people around than in land-clearing applications. As wood and green waste recycling heats up, horizontal machines are getting a ready reception.

At DuraTech Industries International, Inc. in Jamestown, North Dakota, marketing manager Al Goehring says the company has added horizontal grinders to its main line of tub models. DuraTech’s smallest, the 2009, powers a 9 foot tub with a 325 horsepower diesel engine. It can be trailer or track mounted. The 3010 is 475 or 540 horsepower with a 10 foot tub and can be configured in track or trailer versions with a grapple loader option on the fifth-wheel model. The 4012’s 950 horsepower engine turns a 12 foot tub and can be configured with tracks and, on the trailer model, a grapple loader. DuraTech’s newest 9564 horizontal grinder employs a 950 horsepower motor and 64 inch hammer mill unit.

DuraTech’s larger grinders offer an oscillating unloading conveyer. “That means the conveyer not only goes up and down to build the piles, but it also goes left and right, so you don’t have to move the unit as often or have another machine take away the product,” Goehring says. DuraTech has also gone to completely enclosed engine units, using technology developed for agricultural combines. “It reduces the amount of debris and dust and stuff that gets into the engine, which reduces maintenance,” Goehring says.

To traditional markets such as land cleaning and municipal landfills, grinder makers are adding wood reduction for biomass and fuel. “That’s probably the newest market,” Goehring says. “Everybody’s concerned about that. We’re starting to see more and more of the wood being recycled going into that type of activity.”

At Peterson Pacific Corp. in Eugene, Oregon, marketing manager Dave Benton says their 4710B Track Mounted Heavy-Duty Horizontal Grinder is the most popular for recycling. Its 630 to 765 horse-power diesel engine options and 18 inch ground clearance suit it for land clearing at volumes up to 350 cubic yards per hour, Benton says.

In addition to the mid-range 4710B, Peterson recently introduced the 5710C, a 1,050 horsepower track-mounted machine with a spiral stump splitter that can reduce large stumps to grindable size. In March, Peterson will introduce the model 2710 for smaller operations. Newer models have a revised release system to protect against damage from contaminants such as large pieces of steel.

Track-mounted models are Peterson’s best sellers because they require less support equipment such as trucks and loaders and cost less to operate. “You’re moving the machine to the pile instead of the pile to the machine,” Benton says. “Typically the availability of the track-mount machine is at least 10 percent higher than trailer mount, so the track-mount machines are actually cheaper per ton produced.”

Peterson is experiencing healthy demand. “We sell a lot of equipment to the municipal and private recycling yards collecting green waste and various types of woods and that goes into various products including compost and fuel,” Benton says.

Burrows Enterprises, Inc. in Greeley, Colorado, has a niche among recyclers looking for low-cost tub grinders that operate from power take offs on other machinery, typically farm tractors. The company offers standard and low profile models capable of producing 5 to 40 tons per hour, depending on material input and output.

President Royal Burrows says, “Probably most of our sales in recycling would be rose grower and flower growers and nurseries where they want to recycle all their own trimmings and waste.” Typically, these users are grinding nursery and orchard trimmings to create compost, mulch or potting soil for use in their own yards.

The company also sells its RotoTub grinders for composting. “Probably the biggest one would be for composting applications where they end up with a source of composting, like sludge from city sewage plant residue, but they need a certain amount of carbon in there and an air source to keep it fluffy so instead of having a mud product you have air and something to help the bacteria break it down,” Burrows says.

After venturing into sales to more intensive wood recyclers several years ago, Burrows got out of that market due to maintenance concerns when their machines were used in municipal landfills. “Anything that’s wet or has a lot of leaf to it, we grind better than anyone else on the market,” he says. “A lot of these guys want machines that do it all, they want to be able to put in big tree stumps, and we don’t do that.”

Nowadays, in addition to their nursery niches, Burrows is seeing strong demand from cattle feeding operations where users grind up baled corn stalks or hay and mix with chopped silage and other feedstocks. “We can’t build them fast enough for the orders coming in,” Burrows said.