The State of Shredding

The shredding business is benefiting from equipment innovations and high demand for shredded scrap, but it faces ongoing challenges on the regulatory front. 

By Chris Munford

By the numbers, there’s no denying that shredding is the leading sector of the ferrous scrap processing industry.
In 2003, for instance, U.S. steel mills consumed 54.8 million mt of ferrous scrap, with shredded material, or “frag,” accounting for 10.2 million mt—almost 19 percent—of that total, reports the U.S. Geological Survey (Reston, Va.). (The next-closest grade was No. 1 heavy-melting steel at 7.9 million mt, or 14 percent.)
   Shredded is also the most-exported grade of ferrous scrap from the United States. Of the 9.4 million mt of all types of ferrous scrap exported in 2003, 3.6 million mt—38 percent—was shredded material. And demand for shredded scrap continues to grow, even in the face of significant price increases in the past year. That’s great news for the estimated 200 U.S. shredder operators as well as the handful of shredder manufacturers.
   Faced with this growing demand, shredder operators seek to increase their output through better operating practices and/or newer, more-efficient shredding systems. In kind, shredder manufacturers work to make their shredders more sophisticated, more durable, more productive, and—in the end—more profitable for their customers.
Aside from being a profitable business, though, shredding can also be a challenging one due to environmental regulations, maintenance concerns, personnel issues, and the vagaries of the scrap market. Thus, while shredding has never been more important in the ferrous scrap niche, it has also never been more complex and fast-changing. Here’s a look at some of the issues affecting the current state of the shredding art.

Technology and Innovation
From Dry to Damp. One of the biggest shifts in shredding technology in recent years has been the move from dry to wet shredding and, finally, to damp shredding.
   Two decades ago, dry shredding was the standard. This involved the use of air currents and magnets to draw off the lighter materials in the scrap stream. The method worked well, but it produced heat and created dust, which required the use of air pollution control equipment. Then wet shredding came along in the late 1980s, and the dust problem was solved.
   “Wet shredding meant you didn’t need air pollution control, but then you had a huge water-handling issue,” says one scrap industry executive. “The scrap had to be dewatered, and the process water had to be pumped and treated. Maintenance costs were higher.” The past five years have seen a phaseout of many dry and wet shredding plants, he says, adding that “most have gone to damp shredding.” Reportedly, damp shredding now accounts for more than half of the shredder market, and its share continues to grow.
Bigger Is Better—Or Is It? Another major shredding innovation was the introduction of large systems popularly dubbed supershredders or megashredders. These machines typically have shredder-box openings measuring 120 inches or more and are driven by motors or engines rated at 6,000 hp and up.
   The question of whether bigger is better continues to be debated, however. Advocates of supershredders say that such systems deliver better cost-per-ton efficiencies and can accept heavier material that would jam smaller machines. Others contend that supershredders consume more power and require large supplies of feed, which limits locations where they can be viable.
   Supershredders are also more expensive. Hence, these megamachines have tended to be installed by the largest scrap processors—primarily on the East, West, and Gulf coasts as well as on the Great Lakes. Thanks to the recent high scrap prices, several additional supershredder installations are underway or planned, including at inland sites served by rail and river transport such as St. Louis and Nashville.
   One of the nation’s largest scrap processors that already has one megashredder plans to install four more with its joint venture partners over the next calendar year. Another major processor, Chicago-based Metal Management Inc., and a partner are developing a greenfield supershredder site scheduled to be operational by March 2006.
   Rotor Choices. Most shredder operators use tried-and-true standard disc rotors or spider rotors. With the former, the discs have a finite lifespan averaging 400,000 tons of throughput. With a 98-inch shredder, replacement can be necessary every three years—less with a larger machine, sources report. While individual disc rotors can last longer, sooner or later they all need replacing.
   The lifespan of a spider rotor, in contrast, can reportedly be up to 50 percent longer than that of a disc rotor. The downsides are that spider-rotor caps eventually need replacing along with the ends of the spider, which need to be welded on.
   Now there’s an alternative to the standard rotors—a fully capped, barrel-type disc rotor. Barrel rotors are typically specified for larger shredders with hammer swings of 80 inches and up. Though widely used in Europe, such systems are just entering the U.S. market. The chief obstacle to barrel rotors, aside from convention, appears to be their cost, which can be 50 to 100 percent more than standard disc and spider rotors. 
   Still, a Texas processor plans to install the first barrel rotor in the United States by mid-2005. “You get substantially more weight and momentum with this system, and the life of the rotor is just about indefinite because the caps take the wear, not the disc,” says Mark Mullins, North American shredder sales manager for Metso Lindemann (Cedar Rapids, Iowa), which is supplying the new rotor. “After a couple of these units have been running for awhile in the U.S., we think people will take a closer look.”
Recovery Is the Game. Despite technological advances, one aspect of shredding is worse today than in the past: the percentage of metal in the shredder feed. Plastics and other materials have increasingly replaced steel in products from autos to appliances, and this trend shows few signs of abating.
   “Take gas tanks in cars—they used to be made of steel, but now you have plastic tanks. They’re a pain in the neck,” says one shredder. “There isn’t much to be done about the issue overall. But there is an ReMA task force on this, and we’re in talks with automakers. Our position is: If you replace recyclable materials with nonrecyclable materials, that’s a problem.”
   Even as the amount of metal—especially steel—in products declines, other technology is helping shredder operators recover the nonferrous metals, including stainless. These advanced separators process post-eddy-current shredder residue, much of which used to be discarded despite its metal content. The new separation systems increase a shredder’s overall metal recovery and boost revenue, helping operators offset the costs of processing ever-higher volumes of scrap to achieve the same ferrous recovery. (For a detailed look at advanced metal separators, see the March/April 2004 issue of Scrap.)
   Metal Management, for one, has reportedly budgeted $4.4 million this year to buy six advanced metal separators, which the company says will reclaim about $5 million worth of nonferrous metals in their first full year of operation. By recovering this metal, the firm also expects to reduce the tonnage of material it must pay to landfill.
   Another emerging downstream technology for shredders is the crossbelt metal analyzer system from Gamma-Tech L.L.C. (Cincinnati). This system is designed to determine the chemical composition of processed scrap by subjecting it to an MRI-like scan as it passes on a conveyor belt, one recycler explains. 
   This type of analysis will allow older scrap (which can contain excessive levels of prohibitive elements, such as copper) to be processed reliably, with composition-certified grades meriting a premium in the market, sources note.
Several shredders have already purchased this system, with other installations on the way, according to Gamma-Tech.
More Controls, More Control. Controls fall into two basic categories—mechanical and electronic—but the two are increasingly interrelated. In shredders, manufacturers are using the latter to control more of the former.
   Most shredder functions are now operated by computers through programmable logic controllers (PLCs). “In a sense, we’re taking a lot of the controls out of the operator’s hands up in the tower and automating them,” says Denny Schreck of Texas Shredder Inc. (San Antonio, Texas). This automation has led to more and more sensors throughout the shredder. These sensors continuously send information to the shredder’s computer, enabling it to monitor operations and make adjustments as necessary.
   “We’re doing more and more with controlling the feed rolls, as well as the hydraulic cylinders [that raise and lower the feed rolls] and reject doors,” notes Schreck. The goal is to achieve “full-box shredding,” which means keeping the shredder adequately fed at all times so it can process as fast and efficiently as possible.
   Some of the most dramatic changes in shredder technology have come about on the electronic monitoring side. Sensors, scanning systems, remote operations reports, and early-warning troubleshooting are now the norm. This holds especially true for larger shredding operations where multiple sites need to be monitored around the clock.
   Yet, monitoring technology itself isn’t useful if it just means more data. Operators need to know what the data means and what to do with it. As a result, more manufacturers of shredder controls are integrating services into their offerings. Some, for instance, provide the sensing equipment for a moderate installation fee, then charge a monthly fee to monitor and analyze the collected data. One such provider is Motornostix Ltd. (Cincinnati), which synthesizes data from a variety of sensors at multiple sites to put it into a more digestible form.
   “A lot of operators run their shredder at night to get the best power rates. Then the manager comes in the next morning and looks at the scrap pile. That’s how it’s been done for decades,” says Rob McGillivray, a director with Motornostix. “We can tell them whether there was downtime and, if so, how long it was. We can tell them the utilization rate of full motor load,” among other operating details.
   Management receives multiple reports each morning in graphical form. Managers can also log in at any time to check performance at a specific site. The emphasis is on building a picture of the ongoing well-being of the shredder’s motor or other components.
   “We can tell customers something about the health of their machines,” McGillivray says. “We can tell them if a rewind is good—whether a vibration indicates balanced operation or not. We can also provide industry comparisons. We provide some benchmarks that can tell a shredder operator how well they’re really doing.”
   The Motornostix system can track other information as well, such as PCBs in the scrap stream or water purity elsewhere in the plant. The system can also provide a series of alarms to the customer when safe operating levels are approached or exceeded. The urgency of these alarms escalates from emergency e-mails to voicemail messages. If these go unheeded, managers can be phoned in person. 
   Monitoring goes on 24/7, with the system reportedly capable of tracking as many as 50,000 readings a month.
The flip side of monitoring technology, however, is that the increasing complexity and computerization of controls creates the potential for malfunction, which can have far-reaching consequences. “There have been days when technology was the problem,” says a shredder operator. His firm’s longest downtime, in fact, occurred due to a computer glitch.
   Even with such high-tech headaches, few processors want to return to the days when they had less operating information. “Now we dial in over a remote modem, and the technology tells us where the problem is,” the above operator says. “Basically, we’re very excited about the new technology and equipment. It has changed the whole way we do business. Our company monitors everything from belt speeds and drum rotation to cyclone traps and oscillators. The great thing about the shredding industry is that every year there’s new equipment to help us do a better job.”
   In the future, shredder controls could provide even greater detail on machine health and performance analysis. Some research is looking at spectral analysis—a process similar to a CAT scan that is directed at critical pieces of equipment in the drivetrain. This type of high-resolution scan can give operators detailed data on such factors as equipment vibration and imbalance, bearing defects and problems, possible cracks in bearing races, cage defects, and power supply abnormalities.
Shredder technology is also moving toward the use of nanotechnology. Small “machines”—micro-electromechanical sensors—can now be etched into silicon and used to sense minute changes in amperage and voltage flow, for example. This, in turn, can help monitor many kinds of vibration at minute levels and rapid rates. Some industry insiders say it’s only a matter of time before this kind of innovation becomes commonplace in shredder control systems. 
Other notable shredder technology includes radiation detectors, which are now built into many infeed conveyors to detect radioactive sources before they’re processed. In the same vein, shredder manufacturers are introducing infrared detectors to spot unshreddable material before it enters the shredder.
   “We want to be able to detect something as small as four inches in diameter—say, a solid bundle or a steel billet,” says Schreck of Texas Shredder. “It’ll be a $250,000 system, but if it saves you one or two crashes in the first couple of years, the payback should be pretty quick.”
Perfecting Parts. Basic shredder design also provides better value these days. Typical wear parts in shredders have improved designs and greater longevity than before. Some parts today last fully twice as long, such as bottom grates and the main liners inside the shredder, sources boast. System hydraulics, meanwhile, are stronger and more compact than previous setups. Manufacturers have also worked to make it easier to change shredder parts and perform maintenance on their systems.
   On the downside, the general cost of shredder parts and equipment has increased along with steel prices. Metal separators and other downstream components have also increased in complexity to the point that the cost of the downstream system can exceed the cost of the shredder itself.

The Regulatory Gauntlet
TSCA and the Fluff Factor. Shredder operators must meet a host of regulatory requirements on the federal and state levels related to air emissions, storm water, source control, hazardous and solid waste issues, among others. Some of these requirements focus on shredder fluff—the waste at the end of the shredding process—which continues to be the shredding industry’s most-enduring problem.
   Because fluff can contain trace amounts of polychlorinated biphenyls (PCBs), it is subject to the 1998 Toxic Substances Control Act (TSCA). Prior to that rule, any material with a PCB level of more than 50 parts per million (ppm) was automatically considered hazardous waste. Under TSCA, shredder fluff can be discarded in nonhazardous landfills provided special certification is obtained prior to shipment. The certification must state that the fluff to be shipped has been shown, through knowledge or testing, that it may contain PCBs greater than 50 ppm but leach less than 10 parts per billion (ppb).
   Landfills are indeed concerned about the leachability of PCBs in fluff, but a 1991 U.S. EPA study found that such PCBs leach at less than 10 ppb. The PCBs don’t leach, the study noted, because they are fixed in the matrix of the material and are not mobile. Other studies have supported this EPA finding.
   Though PCBs have been outlawed in U.S.-manufactured products since 1979, PCB-containing capacitors can still be found in older scrap such as industrial appliances. Ballasts in old light fixtures can be another source. PCBs were also once used as an ingredient in some plastics. Regarding shredder fluff, TSCA focuses on the removal of small capacitors containing PCBs. Unfortunately for shredder operators, U.S. EPA is interpreting TSCA to mean that all small capacitors must be removed from incoming scrap if operators wish to send their fluff to nonhazardous landfills.
   In late 2003, EPA started enforcing this rule in the Dallas region. In response, larger shredders formed the Responsible Shredders Alliance (RSA), with ReMA serving as an active participant. The group is working with EPA to resolve the issue.
   The problem may eventually resolve itself as PCB-containing products disappear completely from the scrap stream. Readings from fluff samples, in fact, have steadily decreased over the years. 
   The Fluff-Recycling Dream. The PCB issue effectively blocks shredder fluff from being recycled in the United States. In Europe, however, fluff can be recycled—at least in part. Salyp N.V., for instance, has developed one fluff-recycling process that it showcases at its headquarters in Ypres, Belgium. (For a detailed look at Salyp’s process, see the January/February 2003 issue of Scrap.)
   Similarly, Volkswagen AG (Wolfsburg, Germany) and SiCon GmbH (Hilchenbach, Germany) have developed a separation process that can reportedly convert as much as 95 percent of shredder fluff into reusable materials. This proprietary process produces three fractions:
• shredder “granules,” containing hard plastics and rubber that can be used as a blast furnace reducing agent in place of coke or oil;
• shredder “fibers,” containing foam and textiles such as auto carpeting; and
• shredder “sand,” containing glass, rust, iron particles, and “heavy” metals such as copper, zinc, and lead.
   Uses for some of these fractions are still being studied and field-tested. Even if commercially viable uses are developed, fluff-recycling technology is a long way off for the U.S. market. In contrast to Europe, relatively low landfill costs in the United States make such recycling processes too expensive—unless U.S. regulations follow the European Union and mandate fluff recycling to meet higher end-of-life vehicle recycling rates.
Mercury Rising. Mercury switches used in vehicles are another problem for the shredding industry. These switches are primarily used in convenience-lighting packages, such as those in a car’s trunk and hood, with each switch containing about a gram of mercury. While U.S. automakers stopped installing mercury switches at the end of 2002, the switches in earlier vehicles will end up in shredding operations for years to come.
   Mercury is also being used in other automotive applications, including liquid-crystal-diode displays and navigation-aid screens. In addition, some types of headlamps and certain antilock brake systems contain mercury. On the plus side, the amount of mercury used in these applications is a fraction of that used in switches.
   According to the Ecology Center (Detroit), there are about 100 tons of mercury in U.S. cars on the road. Earlier estimates, based on the auto industry’s own data, suggested a higher figure of 150 tons or more. Some automotive mercury ends up in shredder fluff and is eventually landfilled. Fluff samples over time show a fairly consistent mercury level of 2 to 4 ppm, says the Ecology Center. 
   In general, though, mercury switches aren’t broken during shredding. Instead, they end up moving with the shred to steel mills, where they are melted. The mercury then either goes into the air as gaseous emissions or gets captured as baghouse dust, depending on the temperature and ductwork of the mill.
   For shredders, the best solution is to have mercury-containing components removed from scrap cars before they are delivered for processing. After all, once a car has been crushed prior to shredding, the shredder operator can no longer remove any mercury-containing components that weren’t removed at the dismantling stage.
   Fortunately, most dismantlers adequately remove the switches, which minimizes the problem. That’s old news. What’s new is a trend in legislation at the state level that mandates removal of the switches. A law passed by Maine in 2002, for instance, puts the onus on the dismantler but provides a $1 bounty per switch removed. The law also mandates that the cost of the program, including centralized collection centers, be completely funded by automakers.
   The RSA, in conjunction with ISRI, has developed model language for use in similar efforts in other states. New Jersey, in fact, may soon join Maine in mandating mercury-switch removal. In February, the New Jersey Senate passed a mercury-switch bill, and the governor was expected to sign it. Legislatures or committees in at least four other states, mostly on the East Coast, are also said to be considering such legislation.
   The mercury issue is already having a ripple effect on the relationship between scrap processors and their consumers. For instance, the federal Maximum Available Control Technology (MACT) rule requires scrap destined for iron and steel foundries to be free of mercury, drained of oils and other organic liquids, and free of lead, among other strictures.
   In the same vein, there is ongoing discussion about a federal Area Source Rule for electric-arc furnaces. Such a rule could require mills to implement a program to keep mercury and other hazardous materials out of their shredded feedstock. Shredder operators, in turn, would have to step up their source-control efforts and require their scrap suppliers to put greater emphasis on switch removal.

An Eternal Balancing Act
The state of shredding remains a balancing act in which the factors above, and others, come into play on a daily basis. The growing complexity of this balancing act, however, hasn’t kept the industry from processing ever-greater volumes of scrap. Technological innovation, regulations, and business cycles will continue to define the industry. Change will be the order of the day. But the essentials of the business will remain constant: Scrap will still enter the yard at one end, and somebody will still have to figure out how to get it through the process and out the other end safely, profitably, and in an environmentally sound manner. 

Chris Munford is a writer based in New Jersey. He formerly held editing positions with American Metal Market, Platt’s Metals Week, and Metal Bulletin.