Recycling Wire Chopping Plastics

True to their scrap recycling spirits, some wire choppers have found productive reuse and recycling options for their formerly discarded plastic residue.

By Kristina Rundquist

Kristina Rundquist is an associate editor for Scrap.

We’ve all heard Benjamin Franklin’s adage that necessity is the mother of invention.

For wire choppers, necessity truly was the mother of several inventions when it came to their plastic residue, also called plastic tailings. The necessity came in the form of higher disposal fees and stricter environmental tests on wire chopping plastics. The subsequent inventions included the development of environmentally sound treatment options to dispose of the material in a fashion consistent with environmental regulations and—more notably—reuse and recycling options for it.

This is the story of how wire choppers faced necessity and developed the inventions.

Of Tipping Fees and Regulations

The late 1980s and early 1990s will be long-remembered by wire choppers, for it was then they were hit by a triple-whammy. One whammy was the looming shortage of landfill space at the time, which promptly jacked up tipping fees to unprecedented highs in many parts of the country. The second was the EPA’s imposition of a tougher (some would say unfair) testing protocol for residues such as wire chopping plastics.

The third came in the late 1980s with the forced closure of many local landfills that were unable to meet new RCRA regulations. This opened the door to long-distance hauling as the norm rather than the exception.

First, the landfill issue. Think back 25 years or so when land disposal costs were less than $10 a ton and landfills were within 10 miles. In other words, it cost relatively next to nothing for wire choppers to dispose of their plastic residue, which meant there was little incentive to recycle it.

When the so-called landfill crisis emerged (remember the “garbage barge” in New York?), the picture changed dramatically. Landfill fees skyrocketed, especially in the Northeast and other heavily populated areas. In response, wire choppers began to look for ways to reuse or recycle their plastic tailings to keep them out of the landfill (thus, avoiding the steep hauling and tipping fees) as well as keeping themselves out of any potential Superfund liability. Then in 1990, the EPA replaced its Extraction Procedure Toxicity—or EP Tox—test with the more stringent Toxicity Characteristic Leaching Procedure (TCLP).

The goal of both tests was to determine the potential for residues and wastes to leach hazardous or toxic constituents when disposed of in a solid waste landfill. In wire chopping residue, lead—either in free form or as a stabilizing additive in PVC insulation—was the primary concern. Under both tests, material that failed the established threshold was considered hazardous waste and was subject to federal and state hazardous waste regulations.

The EP Tox, implemented in 1980, “was a rather crude test that, in perspective, wasn’t too difficult to pass if you stabilized your material with an alkaline base metal like lime,” says Dick Zampiello, vice president of operations for Schilberg Integrated Metals Co. (East Hartford, Conn.).

Easy to pass or not, the EP Tox test still posed an additional hurdle to landfilling wire chopping plastics. Then, around 1989 there was talk that the EPA might go so far as to declare PVC a hazardous waste. That in itself spurred further research into the possible end-uses of wire chopping tailings as well as ways to segregate the different types of plastics and rubber insulation in the material.

Then, the EPA introduced the TCLP, which “was supposed to give the same readout as the EP Tox test—but it didn’t,” says Jim Gardiner, general manager of Upstate Metals (Canastota, N.Y.), a division of Schilberg Integrated Metals.

What the test did was make it harder for wire chopping residue to pass: With the advent of the TCLP test, the failure rate nearly quadrupled. “Residual metallics—and as a function of processing scrap cable, possibly some free lead—will be present and are almost impossible to remove entirely,” says Zampiello. “It takes only a few slivers of lead per 1,000 pounds to fail the TCLP.”

Moreover, the TCLP test required that all subject solid waste first be reduced to particles 9.5 cm or smaller, which by their nature includes virtually all wire chopping plastics. “Although we argued that with covered landfills there really was no real potential for runoff into streams, the EPA prevailed,” says Zampiello. At the time, he continues, “we could landfill the material if we briquetted it with a neutral binder, but the cost of getting it there was something else again. It just wasn’t economically feasible, so all of a sudden we were in the tailings processing business. That really accelerated the race to look at this plastic as a product and not a waste. The regulatory agencies forced us to move faster than we might have moved otherwise.”

As wire choppers tried to figure out how to deal with the TCLP and what to do with their plastic fluff, their operations continued to generate tons and tons of the material. “We were really in trouble because all that plastic was backed up until we found a solution to the TCLP dilemma and what to do with the material,” Zampiello recalls.

The Evolution of the Solution 

So, there the wire choppers were, with mounting disposal costs and regulatory constraints, and dreams of reuse or recycling options for the material. Then began the hard work of actually finding and developing those options. “The key to development was finding a use that didn’t require the [plastics] to be separated,” says Chuck Gleason, COO of Calbag Metals Co. (Portland, Ore.).

In the early days, the idea of separating the different resins and rubber in wire chopping residue wasn’t on the front burner. Finding an economically feasible way to remove contaminants from the material was. “Keep in mind,” says Gardiner, “that if you want to sell plastic as a product, you have to separate all the waste out, which is any residual copper or aluminum.” Emphasizing this irony, he notes, “First, with the wire chopping line, you’re trying to get all the plastic away from the metal. Now you’re trying to get the metal away from the plastic.” 

There are several methods for readying the plastic tailings for resale. One is hydroseparation (or flotation, a derivation of a mining process) where a thin sheet of water flows down an inclined vibrating table, lifting and carrying the lighter plastic away from the heavier copper. You end up with nicely divided lines of copper and plastic.

Upstate Metals, which processes both insulated aluminum and copper wire, has a different approach. It runs scrap wire through a series of granulators, grinding it into about 1/4-inch pieces. “At this size, the metal liberates from the plastic,” Gardiner says. This plastic and metal chop is then sent over an air fluidized screen bed for initial separation into three distinct streams—metal, mixed metal and plastics, and plastics.

The plastic stream then goes through several more granulations and screenings that seek to remove all nonplastic elements—paper, dirt, rubber and residual metal.

First, the separated plastic passes over a screen where oversize pieces of plastic, and foreign objects, such as wood, are weeded out of the stream. A hydrocyclone then forces whatever has passed through the screen into a sink-float cell, where a “screw conveyor feeds the plastic into a water bath below the surface,” Gardiner explains. As the material passes through the bath, more water is misted on the surface to “prevent material from rafting,” he says, explaining how pieces that should sink may catch a ride on any lighter pieces floating on the surface.

Next, the material is filtered to remove any residual metal and then sent to a second float cell containing water that’s been densified. “Anything heavier, like aluminum, falls to the bottom,” Gardiner says. “This process actually takes out as much as 95 percent of the aluminum present.”

Additional hydrocyclones force any remaining non-plastics, like rubber insulation, up through a pipe for collection, while any residual aluminum falls into a screen below. The emerging stream of clean plastic is dried and stored prior to being shipped in gaylord boxes or large sacks.

Some wire choppers have gone a step further by taking on the herculean task of separating the different types of wire chopping insulation. In one such system, the first step is to run the tailings through a granulation system that removes all steel particles and prepares the remaining aluminum, copper, and plastic/rubber portions for the next step—electrostatic separation.

In essence, an electrostatic separator gives the plastic/rubber particles a magnetic charge and pulls them from the aluminum and copper chops. Then, through further electrostatic separation and/or sink-float and hydrocyclone processing, the different materials—such as PE, PVC, and pure rubber—are separated. These distinct streams of recovered material are then ready for the next stage—recycling.

Working the Recycling Angles

Wire chopping plastics can be used in a variety of products, albeit predominantly low-end ones. Truck mudflaps, nursery bedding trays and flower pots, shoe heels and soles, cable TV insulators, garden hoses, and door mats are just a few of the more common applications. Some automakers also use the material in acoustical barriers in cars.

The material’s use in more traditional consumer products, such as plastic bowls or toys, is somewhat limited, says Gleason. “It’s not a pure product—you’ll have several kinds of plastic and maybe even a little metal. Further, a lot of it is unsuitable for remelting because it loses all elasticity.”

Zampiello says: “As for use in things like high-end consumer products, we have a long way to go.”

Generally, there are three categories of use, says Keith Forrester, president of Forrester Environmental Services Inc. (Hampton, N.H.). One, ironically, is for use in a landfill as a road base. “It’s water-permeable and drainable and the result is a beautiful drainage bed,” he says. A second use is as bedding material, classically in industrial, livestock, or horse-track applications.

Calbag Metals, for one, has sent its material to Recycled Technology Inc. (Tualatin, Ore.), which transforms the tailings into mats for cow and horse stables, as well as speed bumps for cities such as Salt Lake City and Portland, Ore. “Perhaps the number-one benefit,” says William Olson, president of Recycled Technology, “is that these speed bumps simply bolt onto the street and in hot weather won’t lose their form. We’d been using only rubber, but plastic is less expensive and every bit as good.”

Certain wire chopping plastics also make “a reasonably good fuel,” Forrester says. Because plastics are derived from petroleum and natural gas, they have a high degree of stored energy—almost as much as fuel oil and almost twice as much as Wyoming coal, says the American Plastics Council (Washington, D.C.). Forrester adds the caveat, though, that “there are some complications as far as material composition, handling, and size.”  Other options have been in civil engineering applications such as an aeration mechanism in landscaping. “It keeps the ground from compacting,” Zampiello explains.

In the future, he predicts, as technology improves the separation of the different types of wire chopping plastics and as more wire choppers jump on the bandwagon, other more-advanced uses will be applied. There’s also the chance that wire chopping plastics could be approved for use as a daily landfill cover in the same way as automotive shredder residue.

Speed Bumps on the Road to Success

While disposing of wire chopping plastics has been costly at times—and continues to be costly in some parts of the country—wire choppers have found that recycling them can also be expensive. “By the time we’ve installed all the equipment, we’ll have invested more than a $1 million in our plastic recovery program,” Zampiello says. That’s a sizable sum, especially considering that, on average, recovered wire chopping plastic sells for anywhere between 6 and 7 cents a pound. “The costs versus the income tend to offset each other, but it’s really the avoidance of the disposal cost that is perhaps, in the final analysis, the true savings,” he remarks.

Another obstacle to recycling the plastics can be competition from low-cost virgin resin. “Whenever you think you have a hold on things as far as its market application, the virgin material comes into price competition and acts as a deterrent,” Zampiello says. 

On top of that, because of transportation costs and other factors, the market “for recycled plastics is not a steady one,” Zampiello notes, making it hard for wire choppers to invest more heavily in research and development and prototype equipment—a necessity since the end-product manufacturers are tight-lipped about their needs. “The secondary plastics industry doesn’t want to tell you why a certain plastic won’t work, just that it won’t. So for us it’s a constant process of developing a book of knowledge,” explains Gardiner. As Zampiello adds, “If we were making products out of plastic on our own, we’d set up our own labs and models and answer our own application models. We’ve thought of setting up our own R&D and seeing what markets we can target.”

Sometimes the cost of recycling the tailings can be so steep that it doesn’t pay to do it, especially in areas where landfill tipping fees are low. The fact is that the vast majority of wire chopping plastic is still landfilled. Zampiello estimates that only about a dozen or so of the 90 U.S. choppers are processing a significant portion of their tailings.

How easy it is to dispose of tailings depends on several factors. If, for example, you chop wire with PE insulation exclusively, the plastic stream will usually pass the TCLP and can be disposed of in a municipal solid waste landfill without further treatment. If, on the other hand, you chop PVC-coated or mixed wire, the residue will usually fail the TCLP due to the lead and must either be treated, or stabilized, to be accepted at an approved municipal landfill, or—if untreated—it must be disposed of at a subtitle C hazardous waste landfill which is cost-prohibitive. Most tailings that fail the TCLP are stabilized with such patented chemicals as phosphoric acid and less often with conventional methods such as portland cement. In short, you’re applying “some sort of chemical treatment to the tailings that, on a molecular level, changes lead in the material into an insoluble mineral to prevent it from leaching under the TCLP test. Ironically, PVC and PE fluff remain insoluble under acid rain and distilled-water leaching,” Forrester says. “It only releases lead under the TCLP test’s acetic acid leaching method.”

Despite the challenges to recycling wire chopping plastics, Zampiello and Gardiner are optimistic. They see this recycling niche at about the same point that copper processing was some 20 years ago. “Back then, brass mills used about 20 percent copper scrap in their products,” notes Gardiner. “But as technology improved, that level rose to between 80 and 100 percent. We’re at that early point with plastics now, where about 10 to 20 percent of what’s used is recycled. It’s almost a parallel to what happened with metallics.”

So, if plastic recycling in general grows, wire choppers—and their plastic residue—may also benefit. Who knows, maybe someday their plastics will be as recycled as their aluminum and copper. There’s no telling what necessity, and economics, can do. 

A PCB Heads-Up

In its much-anticipated overhaul of PCB disposal regulations under the Toxic Substances Control Act (TSCA), the EPA determined that any wire chopping residue containing PCB levels of 50 ppm or higher now can be disposed of as a PCB bulk waste product at a solid waste landfill. Previously, such material had to be sent to an incinerator or TSCA-approved facility for disposal, says Tracy Mattson, ISRI’s director of environmental compliance.

Another change mandates that employees exposed to residue with PCB contamination over 50 ppm must wear protection to prevent inhalation or dermal contact with PCBs or materials containing PCBs. However, “what protective clothing or equipment must be used has not been specified,” says Mattson. “That’s being left to the discretion of the company.” •