[SHREDDING EQUIPMENT FOCUS] A Diverse Stream

Whether known as shredders, hammer mills, grinders, granulators or some other variation, size reduction equipment is now present within every recycling industry segment.

From the document destruction trucks that pick up office paper to systems that handle obsolete appliances and office equipment, shredders are humming around the world as a critical step in recovering secondary commodities.

Recyclers and equipment manufacturers have set up a number of systems to deal with this diverse stream of materials efficiently and effectively.

OFFICE ONSLAUGHT. An emerging market for shredder makers has been the obsolete office equipment and shredder stream.

In Casa Grande, Ariz., RRT Design & Construction, Melville, N.Y., has helped design a shredding and sorting system for Gold Circuit Inc. that is able to handle a wide variety of obsolete office equipment.

Gold Circuit was formed 11 years ago as two-person gold recovery operation. The company has evolved into a full-service asset recovery and recycling firm that serves Fortune 500 companies, municipalities and other large clients with electronics recycling services, including the shredding of obsolete equipment.

The Casa Grande plant features a high-capacity shredding operation that processes cathode ray tube monitors (CRTs) and other obsolete equipment into secondary commodities, including ferrous and nonferrous metal scrap, plastic shreds, and leaded glass. The company asked RRT to help it design a system that allows for a substantial enough processing volume to make it efficient.

At Gold Circuit’s 73,000 sq. ft. facility, trucks arrive and are weighed. As they are unloaded, the pallets are tagged with a lot number, allowing every shipment to be tracked.

The company says minimal pre-processing is needed, helping it keep costs down. (Only monitor cables are removed, so they can be recycled separately.) The monitors and other equipment are placed onto a 50-foot conveyor that leads to the shredder hopper.

The shredder, made by SSI Shredding Systems Inc. of Wilsonville, Ore., is powered by two 150-hp motors driving four counter-rotating blades. It reduces the feedstock into four-inch fragments. The shredder can handle about 800 monitors per hour, or roughly 26,000 pounds of material.

The outbound fragments pass under an electromagnet to remove ferrous scrap, which is shipped to mill customers.

Scrap remaining after passing under the magnet is conveyed to an "environmental enclosure" that uses a trommel screen, a pulverizer and an eddy current system to separate various materials.

The trommel and pulverizer combine to remove the glass. This CRT glass, which contains recyclable lead, is shipped to a lead smelter. Dust during this part of the process is controlled by a "negative air system." Collected in 55-gallon drums, this dust also goes to the lead smelter.

RRT also helped design and install a new shredding system earlier this year in Largo, Fla., specifically equipped to handle scrap plastics used to make plastic monitor and computer cases.

The Concurrent Technologies Corp. (CTC) facility has been designed to accept post-industrial and post-commercial plastics, including electronics industry casings, and to automatically separate resins.

The U.S. Department of Defense helped fund CTC’s DEER2 project, which is intended to find an environmentally friendly and economically sound way to recover resources from used electronic equipment.

"The plastics recycling application is an important component of the project," says RRT’s Nathiel Egosi. "This is one of the most modern methods to automatically separate the mixed plastics into marketable products," he says of the DEER2 system.

END OF THE ROAD FOR TIRES. Shredding tires for either recycling or disposal has become a standard procedure. What occurs after the shredding is becoming a source of experimentation, as companies try to maximize the recoverable and recyclable portion of the scrap tires.

Columbus McKinnon Corp. (CM), Sarasota, Fla., has installed a CM Tire Shredding System to Lakin Tire West in Santa Fe Springs, Calif.

Lakin Tire West collects and processes more than 10 million tires per year, a daunting challenge both for processing and for finding end markets.

Many of the tires handled by the company are sorted and inspected as good used tires destined for either retread or the global used tire market. The tires that are scrap are either disposed of whole as Tire Derived Fuel (TDF) or shredded and marketed as TDF or into civil engineering applications.

For the Lakin Tire West facility, CM designed a custom system with a special footprint that would integrate with existing conveyor and screening equipment already in place at the Lakin facility.

On the other side of the country, Maryland Environmental Service (MES) is now running a complete Eldan Scandinavian Recycling E-4000t scrap tire recycling system from Wendt Corp., Tonawanda, N.Y.

MES installed the Eldan system at its Baltimore County, Md., facility earlier this year. The plant will process 1.5 million scrap tires annually. The tires will be collected from tire manufacturers, solid waste facilities and scrap yards. The crumb rubber produced will be sold to manufacturers of both consumer and industrial products.

On average, four to five trailer loads of tires arrive at the facility daily to be unloaded directly into the building. Tire generators are charged a tipping fee for tires brought to the facility.

The Eldan E-4000t system installed by Wendt Corp. features a Super Chopper for chopping whole passenger and truck tires into six-inch nominal chucks that are then further processed with the Heavy Rasper. The Heavy Rasper reduces the chunks into chips smaller than ¾ inches while liberating more than 95 percent of the steel wire for separation with a magnet.

The minus ¾-inch chips are then granulated to minus ¼ inches in size in Fine Granulator No. 1 and then to minus 1/8 of an inch in Granulator No. 2. The finished product is designed to be more than 99.9 percent free of liberated steel and fiber.

James W. Peck, MES director, says the department receives no operating funds from the state. The project will be a for-profit venture, subject to the same market forces as other scrap tire recyclers.