Processing e-waste
Electronic waste is a growing problem. A recent study suggests that in the period between 1997 and 2007, nearly 500,000,000 personal computers alone will become obsolete. That figure doesn’t include the hundreds of millions of cell phones and other end-of-life (EOL) electronic items we’ll need to dispose of.

At present, 38 states offer e-waste collection programs. As more and more states refuse to accept e-waste in our nation’s landfills, recycling these unwanted electronic products not only makes sense, it’s becoming big business. In addition to those firms already involved, start-up operations for e-waste recycling are expected in dozens of markets across the country. All of them will need specialized equipment for breaking down our e-waste and harvesting the rich content of metals and other recyclable materials.

Before you buy
For recyclers of e-waste, understanding your needs in advance is essential to making good purchase decisions.

“Electronics recyclers must first know the size range of electronic products they’ll be dealing with,” said Tom Wendt Jr., vice president of Wendt Corporation in Tonawanda, New York. “If the e-waste stream is small and uniform, then we’ll specify the right shredder for that job. But if they plan to process larger, bulkier items, such as photocopiers, server towers or telecommunications scrap, then that requires a different approach, with a larger primary reducer. Most e-waste is lighter gauge material, but there are exceptions such as chassis components of larger electronic products,” he said.

Another important point buyers should consider up front is the required output size of recovered materials. Separation technologies downstream in the e-waste recycling process will vary, so reducing the recovered material to the optimum, uniform particle size is critical for extracting maximum quantities of available metals and other resources.

In short, it is important for buyers to understand what their customers expect and how the recovery system functions as a whole before making any capital investments.

Breaking it down
When e-waste is collected, the obsolete merchandise is delivered to specialized recyclers where demanufacturing typically begins. “The first step for most processors we work with is to remove the leaded glass components and any hazardous materials such as batteries,” said Tom Wendt, Jr. “Once the inbound material is prepped, we recommend that our customers perform a pre-shred to reduce volumes and better prepare the variety of materials involved for liberation,” he said.

Primary reducers for e-waste are most always the low-speed, high-torque variety. There are a number of very high quality primary reducers, such as those from Wendt Corporation, Schred Max or Marathon Equipment for example, that are well suited for reducing inbound mixed e-waste to a uniform rough shred. These powerful units are capable of breaking down nearly anything, including much larger, heavier gauge materials than typically found in e-waste. The resultant shred can then be further processed to meet specific size requirements of the smelter, mill or other end users. For applications such as simple product destruction though, the process ends here.

Rough shred from e-waste is an abrasive cocktail of plastics, composites and metals. Circuit boards, housings, wire and metals including aluminum, steel, copper and precious metals are all part of the mix. Recovering these resources involves breaking things down to a smaller, uniform size that allows the downstream separation equipment to perform as designed.

Shred-Pax, Inc., of Wood Dale, Illinois manufactures a line of dual-shaft shredders suited for e-waste processing. Shred-Pax president Tom Kaczmarek notes, “The dual-shaft design does a nice job of breaking down electronic waste. We normally specify our AZ-45 for primary reduction, and a G-12 grinder for customers requiring smaller shred for recycling.”

Recyclers have even more options for reducing e-waste, however, including shredders with as many as four rotating hook-shear shafts. Bob West, president of Tryco International in Decatur, Illinois, distributors of the Tryco UNTHA shredders said, “Multi-shaft shredders, such as our four shaft model, give recyclers the advantage of processing e-waste in a single pass, often without the need for a primary reducer. The two center shafts are positioned lower in the machine, and perform most of the reduction work, while the outer two shafts direct larger materials back into the center – essentially “recycling” the material within the shredder.” The Tryco UNTHA unit features a built-in screen, which can be changed to produce finished shred ranging from 30mm to 60mm in size. The screen eliminates the need for a separate trommel, and may be advantageous for some recyclers, depending on varying requirements of their customers. “With a four shaft shredder, recyclers get a clean, uniform product,” said Mr. West. “It’s an advantage because separation systems perform better when particle size is consistent,” he added.

David Fleming, Industrial Sales Specialist for SSI, Shredding Systems Inc., of Wilsonville, Oregon has spent more than five years developing specialized e-waste shredding and material recovery systems. His company’s products include multi-shaft shredders designed for e-waste processing. “In higher volume applications, we’ll engineer a “metal recovery module” that includes a rough shred stage, coupled with a secondary shredder or granulator, complete with a changeable sizing screen to produce the optimal size required for our customers. And we can do that with high rates of productivity. The key to material throughput, is sizing screen surface area,” he said. A mid-size e-waste shredding system from SSI for example, is capable of processing 8 -10 tons of material per hour. Larger systems, up to 500 horsepower are also available, with throughput rates capable of meeting demands of even the highest volume operations.

Maintenance
Shredders are versatile, heavy-duty machines. Compared to a lot of the material put through them, e-waste is relatively easy on the equipment. According to David Fleming, “Quad-shaft shredders have a lot more cutting blades. Keeping them sharp is important for maintaining a consistent, high quality shred.” Aside from regular blade maintenance, all e-waste recyclers need to do is follow the shredder manufacturers’ factory recommended schedule for cleaning and lubrication. The expected service life of shredders in e-waste applications should run longer than average, considering the nature of the material being processed.