Trendsetters: horizontal grinders are a popular choice in the C&D recycling market.

Whether reducing the volume of material for landfill purposes or recycling debris into a usable end product, horizontal grinders are gaining in popularity among C&D recyclers. The ability to work in confined spaces and a general reputation for safe operation are just two of the features giving horizontal grinders a leg up in the market over other secondary grinding equipment like tub grinders.

With a horizontal grinder, a recycler can process a variety of material, including mixed C&D debris, clean wood debris, pallets, green waste and municipal solid waste (MSW). In addition, it can be used to make an equally varied number of end products. With C&D-related material, recyclers can use horizontal grinders to do everything from volume reduction to making products like mulch and boiler fuel.

Land clearing may remain one of the biggest applications likely for a horizontal grinder, but its versatility is helping the equipment to gain access to a number of different markets.

SAFETY FIRST

Safety is a high priority on any jobsite, and the horizontal grinder's reputation for safety is helping it gain favor among operators. It's a particularly important issue for ChuckTomlinson, manager of Amerigrow Recycling in Delray Beach, Fla., who says his horizontal grinder--a CBI 6000--is well matched to his specific operation. "We're open to a lot of traffic here and we take in a lot of trucks everyday," says Tomlinson. Horizontal grinders tend to have the edge when it comes to safety--they don't have the reputation for errant discharge that tub grinders do, says Tomlinson, which is why he opted for a horizontal model at his high-traffic facility.

At Amerigrow, Tomlinson says the company mainly processes landscape debris for mulch and compost soil. He says he tried using a tub grinder, but the constant discharge of large materials--including big logs--made it too dangerous, so he invested in a horizontal grinder. "The horizontal grinder has material coming into an enclosed grinding chamber, but with tubs, there's nothing to stop the discharge," he says.

This aspect makes horizontal grinders ideal for work in urban areas, according to Gary Davis of distributor and contract grinder Recycling & Processing Equipment, Peru, Ind. "You can work in confined areas with the horizontal--right downtown," Davis says, a factor which is becoming more important in an industry where urban work and jobsites in and around populated areas are becoming more common.

Larry Doose, president of Silva Corp., Burnsville, Minn., says that horizontal grinders are also less restrictive in the size of material they can handle. "If you're constricted to a 10 or 12-foot tub, introducing the material into it presents a challenge," says Doose, who uses a horizontal grinder manufactured by Vermeer Manufacturing of Pella, Iowa.

While horizontal grinders may offer a number of advantages over tub grinders, they are still subject to contaminants that can cause problems for operators in any market.

KEEPING IT CLEAN

Contaminants come in two varieties: those that pose a threat to the equipment and those that could diminish the quality of the end product. Steel is chief among those contaminants that are dangerous to the grinder, says Charley Duffy, owner of Bull's Eye Demolition in Cape Coral, Fla., which operates a 6700 Peterson grinder to process wood debris for the mulch market. "Obviously, it's bad for the mill," he says.

In addition to metal, rock and concrete must also be kept out of the grinders, first to avoid damage to the machine itself and secondly to keep such contaminants out of the final product, says Recycling & Processing Equipment's Davis.

The grinder operator is the key to keeping these contaminants out of the machine, particularly with C&D debris, which is more likely to contain ungrindable material.

Stan Gibson, recycling specialist for Morbark Inc., Winn, Mich., says proper preparation on the jobsite is the best defense against contaminants. He adds that usually, C&D debris is run across a picking line where the wood is sorted out for grinding.

Although Amerigrow does not accept wood from construction and demolition debris, Tomlinson says his facility does do a visual sort of all material before it is loaded into the grinder with either excavators or backhoe loaders to pull out big pieces of metal before they can cause trouble.

For the high-end mulch market, Doose says Silva Corp. has to be particularly vigilant. "We constantly have to be looking at our material and pulling out contaminants that will degrade the quality of our product," he says. Doose points out treated wood, plastic and garbage as potential threats. He recommends trying to reduce contaminants at the source by training suppliers to provide contaminant-free material. For anything that does get by the suppliers, "our operators are constantly on the watch," Doose says.

On the downstream side, Davis also recommends running the material under a magnet to pull out any stray steel that may have slipped through.

Paying close attention to the infeed material can also help operators extend the life of their horizontal grinding equipment, particularly wear parts like hammers, tips and teeth.

THE LONG RUN

According to Gibson, another advantage of horizontal grinders is that since they are chain-fed machines, a good deal of sand and dirt tends to shake down and exit through the bottom onto the belt, bypassing the hammermill altogether, resulting in more even wear.

However, Gibson still advises operators to run as clean as possible material to get the longest life out of their wear parts. He boils it down to a basic principle: "The cleaner the wood, the longer the life. The dirtier the wood, the shorter the life," he says.

Duffy also says that keeping abrasives out of the feed material is the first step toward saving wear costs. He likens letting too much dirt into the machine to "putting sandpaper on the wear parts."

For additional wear part strength, Tomlinson says operators can also add more carbide to the teeth to lengthen their lifespan.

"Maintenance is your biggest concern," says Duffy. "You have to check your tips and open your mill up every day." He adds that keeping the equipment properly greased goes a long way in preventing wear.

Gibson also recommends that operators make sure their horizontal grinder comes with a proper tramp metal or steel system that disengages the hammermill if it hits a large foreign object. This feature, which protects the machine as well as its operators, comes standard on most equipment, he says, although not all.

An increasing need for equipment that can work in confined spaces has driven the market for horizontal grinders. As markets expand, including attention-getter biomass fuel, operators and manufacturers expect the trend favoring horizontal grinders to continue as well.

The author is associate editor of Construction & Demolition Recycling and can be contacted at jgubeno@gie. net.