Shredding Equipment Focus--The Daily Grind

THE LONG AND SORT OF IT. In many of the markets where secondary grinders find use, the latest trend has been using the grinder in tandem with a primary shredder. Recyclers who are after a high-end product—usually clean mulch for landscaping—employ a number of sorting techniques when using two processors in a system.

Cody Peterson, sales coordinator at Peterson Pacific Corp., Eugene, Ore., recommends three methods of sorting between a primary and secondary processor, depending on the material being ground.

Peterson recommends screening equipment for the removal of abrasive material that can be damaging to the grinder, magnetic separation equipment for the removal of metal and pneumatic equipment for the removal of unwanted paper or plastic material.

Sorting between processors is essential to eliminate any chance of metal contaminants ending up in the high-speed grinder, says Bob Strahm of DuraTech Industries International Inc., Jamestown, N.D. "Certain sizes of metal typically do not bother [the grinder] if it is mixed in with the wood, such as conduit copper pipe and gutter material," Strahm says. "But a thicker, heavier piece of metal can be catastrophic."

In addition, sorting stations between a primary shredder and a secondary grinder should be in place to remove stone, block, carpet, shingles and other materials that, though unlikely to harm the grinder if they’ve been through a primary shredder first, still "must be removed for a clean, value-added end product that can be used for mulch, compost or animal bedding," says Mike Byram, senior director of environmental solutions for Vermeer Manufacturing Co., Pella, Iowa.

In end-markets that demand the cleanest product—like mulch and animal bedding—Tim Griffing, systems engineer for Continental Biomass Industries Inc. (CBI), Newton, N.H., recommends positive sorting of the wood for the best results.

Each market is different, Griffing says, and boiler fuel will not carry the same kind of quality expectations as other products. "It all depends on how strict the specification is," he says.

SIZING IT UP. The tandem setup is particularly popular in the mixed C&D market, says Jerry Morey of Bandit Industries Inc., Remus, Mich. However, in the wood market, the trend is toward bigger machines with more horsepower "because it’s the only machine being used, the one that’s doing all the grinding," Morey says.

"The trend in the United States is primarily toward larger grinders due to economies of scale in production," Byram agrees. "With labor being one of, if not the, greatest cost of grinder operation, some wood waste processing companies purchase larger grinders to increase production while essentially using the same labor requirement needed to operate smaller grinders."

However, the trend toward larger, more powerful grinders isn’t absolute, many manufacturers say. "In the past, the larger grinders were typically the only machines built heavy enough to take the rigors of this application, but today some mid-sized grinders are built for [heavier applications] and offer options to upgrade the machine into a primary grinder configuration," says Peterson. "In regards to the right size grinder, facility size or production requirements will dictate this."

The wood waste industry is growing, says Byram, and attracting companies that might not be able to afford a big grinder when first entering the business, increasing demand for smaller machines. "Additionally, as fuel costs continue to rise, more companies may look at the cost of operation and determine that smaller grinders are less costly to operate."

And in today’s market, customers often don’t have to just decide between large and small—manufacturers say grinders can be tailored to pretty specific needs. "People used to have to guess more," says Vince Hundt, director at Rotochopper Inc., St. Martin, Minn. "But there’s been further refinement in the grinder business where you can tailor the machine specifically to the ton-per-hour throughput that’s being anticipated by the recycler."

Dan Brandon from Morbark Inc., Winn, Mich., says some companies, Morbark included, do onsite demonstrations of a particular machine for customers before they buy to make sure the grinder is the best match for a given operation. "It’s not like buying a car where you take a test drive and say, ‘Yea, I like that one,’" he says. "There’s a lot of experimentation when it comes to getting the best end product."

Brandon also suggests leaving some room to grow when buying a grinder. "Think about buying one size larger than you think you need, because your business is going to grow," he says.

GROWTH PATTERNS. Markets for secondary grinding equipment are growing across the board, manufacturers say. Some private contractors and homebuilders are even in the market for them, although manufacturers recommend they should carefully weigh their options before making a big investment.