Out of the Flames—Recovering from Incinerator Ash

There's gold in them thar ashes. Actually, it's ferrous and nonferrous scrap, and canny recyclers are profiting by recovering metal from the ash at waste-to-energy plants.

BY SARAH HART WINCHESTER 
Sarah Hart Winchester is a Duluth, Ga.-based writer.

While ordinary citizens may look at incinerator ash and smell garbage, a number of scrap processors look at the same ash and smell profits. Recycling metallics—mostly ferrous scrap—from the ashes of burned municipal solid waste (MSW) is big business, and the market is expected to heat up as steel mills seek additional sources of ferrous scrap.

According to the Environmental Protection Agency (EPA), the percentage of metal products in the municipal solid waste stream in 1990 was about 8 percent by weight, or 16 million tons. While a large percentage of these resources are lost to land disposal, many are recovered through recycling programs and, increasingly, the ash from WTE plants. Wheelabrator Environmental Systems Inc. (Hampton, N.H.), for example, recovered last year approximately 143,000 tons of ferrous scrap from ash—dubbed MSW -derived ferrous—which accounted for about 3 to 5 percent of the weight of the total MSW input at its operations, the firm says. Ogden Martin Systems Inc. (Fairfield, N.J.) was close behind, reportedly recovering 130,000 tons in 1992.

Some scrap recycling companies are also getting into the act, buying and processing both pre-burn and, more notably, post-burn metals from WTE plants. "It's just another way to further recover usable materials from the waste stream that haven't historically been considered," says Drew Luntz, president of Luntz Corp. (Canton, Ohio), which works with several WTE plants in Ohio and the East Coast. "It's another arm of the recycling branch."

How It All Began

Most scrap companies involved in the MSW -derived ferrous scrap business entered the field in the early 1980s—though at least one firm, David J. Joseph Co. (Cincinnati), pursued this niche as early as the mid-1970s—as WTE was becoming a popular waste disposal method. In contrast, most of those scrap firms extracting nonferrous metals fromMSW ash only began doing so in the past few years due to the complexity of the recovery process.

It was slow going at first, processors say, because steel mills were hesitant about purchasing a product that came straight from the garbage. "It was very, very difficult to sell," Luntz recalls. "The material smelled, it was unappealing looking, and steel mills were concerned about the density and the melting chemistry of the scrap." In particular, mills were concerned about the tin level of the material.

In the mid-1980s, however, steel mills set their sights on less expensive sources of ferrous scrap, and a market was born for the previous ugly duckling of the scrap industry. Today, says Gregory L. Crawford, vice president of recycling operations for the Steel Recycling Institute (Pittsburgh)," MSW -derived ferrous has earned a reputation as being a usable and desirable form of scrap because it has a chemical predictability and the price is right."

In fact, according to Michael Friedman, president of Friedman Metals Brokerage Co. (York, Pa.), almost all American steel mills are looking past the scrap's smelly exterior to take advantage of its consistent performance and lower cost. "If they're not," he says, "they're losing out on a good way of lowering their cost of charge." Indeed,MSW -derived ferrous is several dollars per ton cheaper than other ferrous scrap grades, though, as with other scrap, the amount of processing affects the sales price. When shredded, for instance, MSW -derived ferrous is usually sold at a discount to traditional shredded scrap, whereas when it is marketed with minimal processing, it is typically priced as No. 2 material.

Despite its low-budget reputation, proponents insist that MSW -derived ferrous can be used to make high-quality steel. "This grade of scrap has found its own niche, typically in minimills," notes Crawford. "It's most often used to produce heavy shapes, such as rebar or billets, rather than flat-rolled products."

Getting to the Goods

Before MSW -derived scrap can be sold, of course, it must be recovered, and the road to recycling this material begins at the WTE plant's door, where larger pieces of ferrous are typically pulled from the MSW mix upon arrival. The remaining material is then sent into the combustion chamber for about 45 minutes.

While the heat inside the boiler reaches temperatures of 1,800º to 2,500º F during the burning process, the ferrous scrap reportedly doesn't melt. "Nonferrous products and smaller steel items, such as a drawn steel can, will crumple," says Patrick Scanlon, director of recycling for Wheelabrator Environmental Systems, "but most of the steel remains intact and indistinguishable from ferrous materials that didn't go through the burn process. There is little, if any, melting of steel." In some instances, the combustion process actually benefits scrap recovery since it can liberate metals that were previously in a difficult-to-recycle or unrecyclable form, such as nails and screws in wood, bedsprings, metal-plastic composites, and some automotive parts.

After the MSW is burned, two ash streams remain: the fly ash, which, because it may contain some heavy metals such as cadmium and lead, is typically disposed in ash monofills (landfills that contain only one kind of waste); and the bottom ash, which accounts for 85 percent of the total ash and contains the ferrous scrap of interest to scrap processors and steel mills. Although the composition of the bottom ash can vary greatly from WTE plant to WTE plant, ferrous materials generally account for most of the ash by weight. "Some facilities generate scrap with insignificant amounts of ash, while others generate material that can be 50-percent ash," observes Luntz.

Eliminating Ash for Cash

Before the scrap can be recycled, of course, either the WTE operator or the scrap processor must separate the MSW -derived scrap from the ash. This process, known as beneficiation, can be done either at the WTE plant or at a scrap facility, but most processors choose the former option for the obvious reason that they can recover the scrap and leave the ash at the WTE facility, thus requiring limited hauling back and forth. "We prefer to do cleanups on-site at the WTE plants, and we try to do it with their equipment," says Luntz. "We will add our own equipment, such as shredders, shakers, magnets, or air systems, if necessary—whatever's needed to tackle the individual characteristics of the scrap a plant generates."

Those processors who opt to beneficiate the scrap at their own plants are allowed, in most cases, to return any ash they separate to the WTE plant. "It's a point of negotiation between the scrap processor and the WTE operator that the processor can return a certain percentage of the ash," says Friedman. This is important because, as Friedman points out, even though the metals/ash mix may only contain a small percentage of ash, that small percentage can quickly turn into tons because of the large quantities involved.

Regardless of who handles the beneficiation or where it's done, chances are it follows the same basic mechanical processes to extract ferrous materials from ash: The cooled bottom ash is dropped onto a shaking screen called a grizzly, which separates larger components from smaller ones. As the screen shakes, the smaller items—those less than 12 inches—drop to a conveyor, which carries them under a series of magnets that pull the ferrous scrap from the ash. The larger ferrous pieces on the grizzly screen are conveyed directly into a separate vehicle or container. At this point, depending on how much residual ash is in the scrap, the recyclers may decide to further clean and process the two different-sized groups of scrap, though it may be more desirable to market the material as is.

When it comes to recovery of the nonferrous scrap in incinerator ash, methods are more experimental, though there are a number of proprietary systems being used. The nonferrous recovery is so developmental, in fact, that scrap processors remain tight-lipped about how they extract the scrap and to whom they sell it. While scrap dealers agree that recovering scrap from ash provides dependable profits, they aren't as united in their marketing methods. Some prefer to mix it in with other types of scrap, while others insist on labeling it as a distinct, readily identifiable grade, selling it on its own without blending it with scrap derived from other sources. "We generally sell our MSW -derived ferrous as a separate, unique product," says Rick Jordan, vice president of the municipal recycling division of Joseph Co., which purchases and/or processes MSW -derived scrap from all over the country. As part of this marketing strategy, the firm works to educate its consumers about the benefits of MSW -derived ferrous, stressing analysis and consistency of availability.

A Good News/Bad News Scenario

The benefits of recovering metals from ash are both economic and environmental, and herein lies the reason for taking the trouble to dredge through the ashes of what was once a community's garbage. Scrap processors profit by recovering the ferrous metals from the ash and selling it to eager steel mills. Though recyclers usually can't command the same prices for MSW -derived ferrous as for other ferrous scrap, the profit margin is still good, many say.

The environmental benefits are equally important, and they tie into the profit motive as well. As Jordan notes, "It's a pleasant experience when one can do society good and make a profit at the same time." Doing society good comes from recycling metals that had previously been buried with the ash. This not only frees up landfill space, but it saves the WTE plant and its client community from the charges they would pay to bury a larger quantity of ash.

While the benefits of recovering and reselling MSW -derived ferrous are clear, there's one cloud on the horizon. In the next few years, the U.S. Supreme Court will decide whether ash from MSW incinerators should fall under the household waste exclusion of the Resource*, which has exempted it from toxicity testing requirements, or whether it must now be tested to determine if it's hazardous. Scrap recyclers and executives in the WTE industry admit that if the court decides the latter, it could cast MSW -derived ferrous in a negative light, but none believe it poses any real problems for the future of this niche. "Whatever the court finds, it won't diminish the attractiveness of extracting ferrous and nonferrous metals from ash," says Garrett Smith, manager of recycling programs for Ogden Martin. "I think the desirability will remain."

There are several reasons for the industry's optimism regarding the impact of a possible reclassification of ash. For one thing, some industry experts believe the Supreme Court will let stand the current household waste exemption. "It's unlikely the Supreme Court will determine that municipal waste ash will require testing," says Smith. "It's more likely they'll go along with the current law." WTE operators maintain, even if their ash must be tested, if anything would require handling as a hazardous material, it would be the fly ash, not the ferrous-rich bottom ash. Furthermore, scrap recyclers point out, the WTE operators or the host communities, not recyclers, are ultimately responsible for ash handling and disposal.

Despite this potential shadow on the market, most recyclers of MSW -derived scrap expect nothing but growth for the material. For one thing, Friedman notes, "recovering ferrous from ash will increase in the future because there are many landfills that are expiring." To be sure, recycling MSW -derived scrap reduces the quantity of ash and other waste to be disposed, thus extending the lives of existing landfills and recovering valuable resources. "It makes good common sense," says Luntz. "I see this as one way to get the oink out of the pig of the whole garbage problem."

While most existing WTE plants already have some sort of metal reclamation activity, economics and legislation seems likely to encourage all MSW -derived metals to be recovered in the future. As Scanlon asserts, "You can bet that we'll be maximizing the recovery of ferrous metals at all of our future plants." As for the recovery of MSW -derived nonferrous, he adds that Wheelabrator "would love to pursue a viable way of getting all nonferrous scrap out of the ash."

Meanwhile, processors assert that the future will also see more and more scrap consumers turning a favorable eye to MSW -derived scrap. In fact, Jordan predicts optimistically, MSW -derived material will eventually become as mainstream a scrap item as its traditional metallic scrap brethren.