Insider information: C&D recyclers offer their advice on selecting and optimizing wear parts for shredders and grinders

Construction & Demolition Recycling, May-June, 2004 by DeAnne Toto

Wear parts can represents considerable portion of C&D recyclers' operating costs. After all, as Carl Busse of concrete recycler Vulcan Materials, Elgin, Ill., says, "We are in the business of wearing out equipment. The outcome is some rock on the other end." And the more tonnage a company processes (or the more rocks or sticks it produces), the more money it is likely to spend in wear parts.

While the price and the quality of the wear parts figure into a C&D recycler's choice, they are not the only considerations. Additional services, such as inventory assistance and reverse engineering, are also valuable to C&D recyclers and can give one supplier an edge.

In addition to the help and support they get from wear part suppliers, C&D recyclers themselves can also take a few steps to extend the life of their wear parts and to control their costs to some degree.

MONITORING WEAR. Most C&D recyclers monitor their wear parts costs rather closely, and many agree that their operators' knowledge can have a significant impact on their longevity.

"It is the knowledge of the people that really makes a difference," Busse says. "Experience is tough to beat."

"A poor operator can cost you a lot of extra money," Dennis Blanchard of Recovermat, Halethorpe, Md., says. Recovermat is a processor of mixed C&D material. "Watch your operators and try to make sure that they are taking good care of the machines," he suggests.

Gino Edwards of Environmental Resource Return Corp. (ERRCO), Epping, N.H., says experience is the best teacher when it comes to wear parts. ERRCO grinds wood for the New England boiler fuel market, processing roughly 70 tons per hour.

"We've been doing this now close to 10 years, so we've got a pretty good idea how long it takes for something to wear out and when something should be replaced," Edwards says. ERRCO replaces the hammers in its crushers every three months, while the impact plates usually need to be replaced every four months he says.

"We do spend a lot of money on wear parts," Blanchard says, "because this is a hammermill and we change hammers weekly." Recovermat has used an auto shredder to process C&D material since September of 1996, having processed more than 800,000 tons of material during the period.

Blanchard says that the hammermill's interior wear parts last for years in his operation. "We just replaced, relined and re-guarded the mill." He adds that this was the first time some of the linings had been changed in the eight years Recovermat has been operating its shredder.

Busse says that constant maintenance of Vulcan's processing equipment helps to ensure that the company gets maximum life from its wear parts. He also says that Vulcan tracks its costs very closely. "We've got it down to very tight figures," he says. "We know exactly what we spend on what, when and where. It enables us to do what we do as efficiently as we can."

Vulcan replaces its horizontal impactor blow bars most frequently, Busse says. "The horizontal impactor has the highest wear as opposed to the test of the equipment," he says, adding that Vulcan's cone crusher's wear parts are replaced least often.

A shingle grinder located in the Midwest says that 25 percent of his costs can be attributed to wear parts. "Shingles are very abrasive and very tough to grind. It is a high wear, high maintenance process," he says.

He asks his operators to be very observant in order to avoid contaminants when loading the shingles into the grinder. "He needs to make sure that there is the proper amount of water going in for dust and for wear. When we get the proper amount of water to control the dust, it also helps to slow up the wear some," the shingle recycler says.

In addition to having quality operators and monitoring the in-feed material for unshreddables, recyclers can also extend the longevity of their wear parts through hard facing and rotating some wear parts.

EXTENDING LIFE. The shingle recycler rotates the bits in his grinder in order to extend the life of his wear parts and to keep replacement costs down. "We rotate some of them that are not quite worn to the outside and put new ones in the main course," he says. "But sometimes that gets to be nonproductive," he says, adding that with the time restraints of some jobs, it makes less sense to rotate the bits. "Out of a given tip in the real impact zone, I can see as much as two eight-hour days of processing," the shingle recycler says.

The bits the shingle recycler uses are cast of a forged bit body made from AR 400 steel with hard carbides soldered into their heads, he says, while other wear parts may get a carbide-impregnated overlay. "It gives them a really rough, abrasive finish," he says of the overlay. Additionally, the recycler uses a quarter-inch Trimay overlay on his screens, which are made out of A 36 steel.

Before adding the Trimay overlay to his screens, the shingle recycler was able to process 2,500 tons before the screens needed to be replaced. Now, he says he gets anywhere from 4,500 to 6,000 tons processed before the screens need to be replaced.