Supplement -- Scrap Processors Can Meet the Quality Changes

The domestic market for ferrous scrap has been strong for North American processors—and it will continue to be provided they can meet the narrower specifications demanded by the steel mini-mills.

The mushrooming of mini-mills over the last two decades has not only changed the amount of demand for ferrous scrap, but also the nature of the demand. Mini-mill operators—and their customers—want steel that is practically devoid of harmful impurities. To produce steel that good, the first step is to procure high-quality scrap (or scrap substitute) for the melting stage.

While steel quality is often defined by a lack of troublesome impurities, the economics of producing steel have not been set aside. What steel makers seek is the “least cost suitable charge” (LCSC), according to Dr. Richard Burlingame, a consulting metallurgist from Cleveland. Software programs that take into consideration both pricing and chemistry have been designed to allow steel makers to feed their furnaces a blend of materials that has the appropriate melt attributes while using the commodities that currently carry the lowest price tag.

LEAST COST SUITABLE CHARGE

The LCSC goal is a microcosm of the standard challenge facing most manufacturers: making a quality product at a low enough cost to sell that product at a price the market will bear.

LCSC “is what it all comes down to,” says Burlingame. “There are software packages being used by steel companies and scrap companies that have been created to determine this,” he notes. “These programs help you figure what you should be melting, depending on costs and chemistry.”

A successful melt can be considered one where the chemistry goals are met while the materials used did not cost the company considerably more than the lowest amount possible. Steel makers have different methods of achieving this goal, some involving long-term strategies and others utilizing up-to-the minute pricing data. Most methods, of course, involve a mixture of planning and timely decision-making. The methods can also be a combination of newer software with time-tested manual sorting techniques.

North Star Steel Co., Minneapolis, uses a software package at its mini-mills to help it compute the LCSC of every melt. At its North Star Recycling subsidiary, manual inspection methods are cited by vice president-general manager Jim Jonasen as being critical to the scrap quality process.

Manual pickers are employed to sort through the ferrous shred created by the company’s shredders. The pickers look for attached non-ferrous items, such as copper, rubber or fluff that may have made it through the previous separation processes. “They are good at what they do, and they can help knock down your copper level by a couple of points,” says Jonasen.

Nucor Corp., Charlotte, N.C., is in the course of examining the ways inbound scrap is tested and screened, according to Jim Frias, controller of the company’s Crawfordsville, Ind. mill. Currently, the company’s process is more manual than automated, he notes.

The company currently looks at LCSC issues formally on a monthly basis, he notes, with his mill’s melt shop manager and general manager meeting once each month to “look at recipes to try to get the ideal melt quality-melt value relationship.”

“We at Nucor give operators a lot of control; they have the authority to make changes,” Frias says of melt shop recipes and operations. “They’re the ones who, on a heat-by-heat basis, see how materials are performing.”

SEVERAL DEGREES OF SEPARATION

When it comes to melting scrap, low levels of “tramp elements”—copper, nickel, chromium, tin, molybdenum, and others—are vital for steel makers.

Scrap processors have a number of methods available to help them provide ferrous scrap that minimizes the presence of these elements.

Processors with shredders are taking advantage of automated methods that can help in the creation of cleaner shred. Eddy currents separators and heavy media separation systems can help screen out nonferrous metals and other materials.

As with North Star and Nucor at the mill end of the process, the human touch is still valuable at the processing stage. Scrap processors with one or more industry veterans who can spot potential problems before they are delivered to a mill have an advantage. Such individuals go a long way toward helping a processor establish and maintain a winning track record with mills.

SPECTROMETER STILL A KEY

Metallurgist Burlingame believes scrap processors who want to maximize their odds of building a winning track record with mills would do well to purchase and use spectrometers, LECO units, and other analytical devices.

Burlingame believes he may have been responsible for the presence of one of the first spectrometers at a scrap processing facility. During his tenure with Luria Brothers more than two decades ago, the company had agreed to provide ferrous scrap to a consumer who required the scrap to be extremely low in chromium content.

His solution was to utilize a spectrometer to analyze a sample (or button) from every shipment that was to go the client. “It was a tedious job, but it really worked well,” he recalls of the routine of analyzing a sample from truck load after truck load of turnings.

Burlingame says that this particular application was “a typical kind of scrap yard use. It’s tedious, but boy did it work beautifully.”

He believes processors could eliminate most quality complaints if they correctly employ one spectrometer and one dedicated technician to analyze samples at appropriate times. “You don’t need an engineer or chemist,” he remarks. “You need a bright, motivated person who enjoys working with computers and who relishes solving problems that creates order from chaos.”

SUBSTITUTES: THREAT OR COUNTER-BALANCE?

If scrap processors need one additional incentive to put their quality houses in order, it might be the steel industry’s interest in scrap substitutes.

A number of steel companies—including some of the largest such as Nucor Corp. and Birmingham Steel Corp.—have made significant investments in facilities to produce scrap substitutes to feed their own furnaces.

Some of these substitutes have been available in some form to consumers for a number of decades. Along with pig iron, they are among the resources mini-mill operators can turn to when scrap prices escalate or the scrap grade they are looking for is scarce.

Pig iron is the cast iron produced in blast furnaces. It can also be used in electric arc furnace melts. It is highly-regarded by mini-mill furnace operators and is often used to “sweeten” melts that may primarily consist of a lower grade of scrap or scrap substitute.

Direct-reduced iron (DRI) is the most commonly used scrap substitute. It consists primarily of high-grade iron ore that has been almost completely reduced to metallic iron by natural gas. A joint venture between Birmingham Steel Corp., Birmingham, Ala., and GS Industries Inc., Charlotte, N.C., will result in a DRI production facility in Louisiana.

Iron carbide, conceived of in the 1970s, is among the newest scrap substitute options available to mills. Natural gas is also used in this iron ore-reduction process that ideally results in a material that is about 87 percent iron and about 6 percent carbon. Nucor Corp. and Steel Dynamics Inc., Butler, Ind., are among the mill operators investing in iron carbide production facilities.

Molten iron mini-smelters are being designed and tested as a newer means of using pig iron in electric arc furnaces. In theory, a mill operator saves time and energy in the electric arc melt stage by using the molten material that is directly fed from these small smelters to the electric arc furnace. North Star Steel Co. has signed an agreement to install Technored molten feed furnaces at one or more of its U.S. mills, provided they are satisfied with a test project currently taking place in Brazil.

Do these substitutes present a threat to the continued need for ferrous scrap? Burlingame looks at them more as “counter-balances” than threats. “These scrap substitutes are part of the perpetual balancing of virgin-type materials and scrap,” says Burlingame. “Scrap will always be used because it is always being generated. It is what I call a national resource.”

From the perspective of steel companies, the substitutes “act as the counterweight of scrap prices going too high,” Burlingame remarks.

Jim Nuckels, chief operating officer of Pacific Coast Recycling, Long Beach, Calif., offers similar remarks. “Sometimes they can allow the mills to take some of the lower-grade scrap that might not have been used,” says Nuckels, referring to melts that blend materials.

He also sees the materials as a check on ferrous scrap prices rising to unprecedented heights. “When you have DRI or pig iron in the $160 per ton range, obsolete scrap will not rise to $200,” says Nuckels.

Even though some steel companies may be investing seriously in the substitutes, Burlingame believes scrap still offers some of the best melting qualities. In terms of melting yield—defined by Burlingame as the weight fraction of molten material produced from a ton of feedstock—prompt number one grades of scrap cannot be matched, he says, certainly not by DRI.

A high melting yield is obtained by minimizing the contents of combustibles, easily oxidized elements, and slag forming gangue minerals. Steel makers who consume oily turnings or shredded scrap containing too much fluff are using their furnaces as expensive incinerators. Even pig iron suffers several percent of yield loss as carbon, silicon and manganese are oxidized out of it. The one advantage of DRI—its very low tramp element content—is offset by its low melting yield, some contend. The low yield of DRI, typically 87 to 89 percent but falling to the low 80s if there are production glitches, is the result of its contained gangue minerals, unreduced iron oxide, and carbon. Gangue minerals, mainly the SiO2 and other minerals present in the original ore, not only reduce the yield but also consume lime refractories and energy as they are converted to slag.

Number one grades of scrap, on the other hand, are up in the 95 percent to 98 percent range, Burlingame says. “A ‘real cost’ of scrap or substitute should be determined by looking at both the cost of the delivered material and the melting yield. A low yield can drive the real cost of a scrap ‘bargain’ to very high levels.”

In the summer of 1997, Burlingame and Nucor Corp. president Ken Iverson engaged in a gentlemanly debate in the pages of Iron & Steelmaker magazine over the status of Nucor’s iron carbide project. (The company built an iron carbide production facility in the Caribbean nation of Trinidad & Tobago.)

“The purported advantage of iron carbide is that it dissolves instantaneously, and that the contained carbon burning in the injected oxygen produces a tremendous exothermic reaction. This chemical energy foams up the slag and removes nitrogen. This is supposed to be so energy-efficient that it allows you to reduce your electrical energy usage significantly,” says Burlingame.

But no one has published data to prove this, he claims. “It hasn’t been demonstrated yet.”

In his response, Iverson said that many of Burlingame’s criticisms are valid, but added that the company is still in the early stages of researching and developing its iron carbide. “It would be well to keep in mind that most of the producers of metallic scrap substitutes, including DRI, took more than five years to commercialize their products successfully,” he wrote. The Trinidad facility began production operations in late 1994.

Burlingame is an admirer of the mini-smelters, at least as they are described in theory. “If they work as promised, I think the last DRI plant has been built,” he boldly predicts. He also notes that even if they work as promised, their use will still be dictated by the price of a commodity (pig iron) and its availability—making it a counterweight to ferrous scrap instead of a replacement.

KNOWLEDGE AND ATTENTION TO DETAIL

Astute scrap processors, Burlingame believes, should be willing to perform their own LCSC analyses and be vigilant about analyzing outbound shipments. “The sharp scrap company will be able to say to its consumers: ‘Look, we’ve got the spectrometer, we’ve got the LSCS information. We can assure you that we  . . . will do things right’.”

Such an attitude he believes, can help processors assure consumers that they can provide not only the material they need, but also the in-house knowledge that companies increasingly seek from their suppliers.

The author is managing editor of Recycling Today.