May/June 1996
This German manufacturer of magnetic equipment sees its patented eddy current nonferrous separator as the key to making its mark in the North American market.
By Paul Belden
Kent Kiser is associate editor of Scrap.
It’s a midweek business afternoon in Germany, and Dieter Henke’s normally flawless command of English is deteriorating in a crossfire of craziness.
An Italian delegation of separation equipment buyers is on the doorstep, a group of Korean scrap processors is due at any moment, sales orders are coming in, and, to top it off, some crazy writer from an American recycling magazine is on the phone asking about the biggest magnet he’s ever seen. “I’m sorry, I have much to finish here,” he says, tartly, into the phone. “I have no time to speak of this.”
But the question is one that Henke can’t seem to resist—not even with a million things to do and no time to do them. He gives in without much of a fight.
“The largest magnet I have seen is a circular lifting magnet with a diameter of 3.2 meters.” He goes on to explain that this particular magnet, manufactured by his company, Steinert Elektromagnetbau GmbH (Cologne, Germany), and now in use in the north German port of Bremen, weighs 18 tons and can lift 5 tons of scrap iron at a time.
With only minor prodding, Henke spends the next hour discussing magnets in all their glory and all their many uses in the scrap recycling industry. As he warms to his theme, his English smooths out and a cool British accent is revealed. The craziness of the midweek business afternoon is forgotten.
It’s only a temporary respite, as Henke well knows. As Steinert’s export manager, he’s come to expect the daily unexpected crisis these days.
His company, founded in 1889, has long been a supplier of circular magnets, drum magnets, and electromagnetic separators to the scrap industries in Asia and Europe. But now, on the strength of a key (and jealously guarded) technical patent for its latest product, an eddy current nonferrous separator, Steinert is putting an unprecedented focus on the ultracompetitive North American market as well.
Leapin’ Aluminum
Used in the scrap industry primarily to increase the amount of aluminum extracted from shredders’ mixed nonferrous streams, an eddy current separator—ECS for short—is, in simplest terms, a magnetic system for segregating nonferrous metals. Yes, you read that right, it uses magnets to separate metals every scrap recycler knows aren’t magnetic.
Actually, an ECS relies on a quirky side-effect of electromagnetics. As the English scientist Michael Faraday discovered in the mid-19th century, an alternating electromagnetic field induces small electrical currents in certain nonferrous materials and these currents have the effect of turning a normally nonmagnetic metal into a kind of temporary magnet. And because the poles of this temporary magnet are aligned with the poles of the alternating field, the net effect is repulsion. In fact, the two fields repel each other the same way that two ordinary magnets will slide away from each other when placed end to end with like poles together.
In practical terms, an ECS works by exposing a moving stream of mixed materials to a rapidly alternating electromagnetic field emitted by a set of powerful magnets lined up in an alternating-pole sequence located within some drum or belt pulley that acts as the end of a feeding conveyor. The magnetic field creates eddy currents in the nonferrous particles riding the belt, with the result that these particles leap out of the stream like salmon in spawning season, while remaining materials simply drop down when they reach the end of the belt.
Solving Eddy Problems
While this process is straightforward, applying it as nonferrous separation technology on shredder lines has not been without its challenges, Steinert’s executives point out.
The company’s first ECS prototype—built back in the mid 1980s—was a disappointment, Henke says. It used a linear motor to produce an alternating field through which a belt moved horizontally, forcing nonferrous particles to jump sideways off the belt upon reaching the field. One problem with this prototype, he says, was that the linear motor required too much power to be really cost-effective. And on top of that, the sideways jump made for a lot of deflections and blocked shots, which reduced the quality of the separation, he notes.
So the linear system was scrapped, and a rotor system was built. In Steinert’s rotor system, an alternating magnetic field is produced by means of a drum rotating within a larger belt pulley that rotates independently from the drum and at a much slower speed. Nonferrous particles jump out of the stream at the point where the belt drops to go around the pulley.
With this design, the manufacturer knew it had found solutions to the problems of deficient power and blocked shots. Flushed with success, Steinert built seven prototypes and started making marketing plans.
But every one of the machines failed within months, victims of what came to be known as “the ferro problem.” Apparently, small iron particles in the stream—especially those 1 to 3mm in diameter—were so attracted to the powerful rare-earth magnets in the drum that they were chewing up the belt to get closer to the magnets. Even more damaging, if a particle managed to squeeze itself under the belt, heat and rotation caused it to act as a drill. With a horde of hot little bits of iron drilling themselves into the housing, it was only a matter of time before the pulley failed.
Back to the drawing board it was. After a good deal of trial and error, Steinert’s engineers hit upon the beautifully simple idea of offsetting the drum magnet within the pulley housing.
Most ECSs are built with the drum magnet located in the exact center of the larger belt pulley. This system is known as the “concentric” configuration because the respective diameters of the two cylinders form concentric circles. As Henke points out, in a concentric system, the alternating magnetic field encompasses the entire pulley, which means iron particles tend to stick to the belt all the way around the pulley.
What Steinert engineers did was simply move the drum magnet upward within the housing, to about the 1 o’clock position when viewed end-on. This way, the alternating magnetic field encompasses only the top part of the pulley. As iron particles follow the belt around the pulley, the diameter of the pulley itself forces them out of the field. And once out of the field, they drop off the belt, Henke says.
This “eccentric” design dealt with the ferro problem so well that Steinert patented it immediately and went straight into production. The first eccentric-model Steinert ECS came out in 1987. It had a 20-inch-wide belt and used a 1,400-rpm drum magnet. Three years later, a 40-inch-wide model was introduced and, four years after that, a 60-inch-wide model using a 2,600-rpm drum magnet.
It has proved to be one of the most significant technical innovations in the company’s history, responsible for bringing in millions of dollars of revenue. In 1995, Steinert celebrated its 300th ECS sale and its third consecutive year of rising revenues—which grew from 20 million German marks (about $13.3 million) in 1993 to 30 million marks (about $20 million) last year, primarily as a result of the ECS, company officials say.
It Doesn’t Come Cheap
Despite such impressive figures, Henke is, at the moment, feeling particularly unsatisfied. What’s frustrating him is the difficulty of getting some companies to see what, to him, is so obvious: the economic sense of buying Steinert.
It’s a frustration that has particularly plagued the company in its marketing efforts in North America, where the ECS competition is fierce and Steinert’s is one of the most expensive systems on the market, if not the most expensive.
But there’s a payoff, Henke claims: defeat of the ferro problem, which actually ends up saving users money in the long run, he says. “You would be surprised how many people are buying from the left pocket and paying repair bills out of the right pocket. When they buy, they don’t know the trouble they will have,” he says, adding, “I have heard that some people with concentric models have to stop their machines once or twice a shift to clean the pulley housing with a mop. If you calculate 30 minutes of downtime for every shift, you’ll see that it adds up very fast.”
The unfamiliarity of many recyclers with the whole concentric vs. eccentric matter has in fact been the largest obstacle to Steinert’s gaining ground in America, says Phil Lombardo, president of Steinert Inc. (Lakewood, N.J.), the subsidiary that handles North American sales and service.
This was especially the case in the early years, when Henke and Lombardo traveled across the country together knocking on doors to pitch a new product at a price substantially higher than its competition. But they did make the difference clear to a few early buyers, who remain impressed with the Steinert design.
Don Wolfram, vice president of engineering for Resource Recycling L.L.C. (Pinellas Park, Fla.), is just such a buyer. The two first-generation eccentric model Steinert ECSs his company bought in 1988, he points out, are still going strong, recovering metals from municipal waste-to-energy slag. “They’ve both got in excess of 15,000 hours on them, and we haven’t had to replace anything other than an occasional belt,” he reports. In contrast, he says he’s heard “horror stories” about belts and pulley housings of concentric models burning through in less than a month.
How to Use an ECS
The recycling applications for ECS are varied, with recyclers using them to extract aluminum caps and rings from ground plastic bottles and glass cullet, recover nonferrous scrap from demolition debris, separate aluminum and plastic containers at material recovery facilities, and concentrate precious metals in shredded computer scrap. But what Henke and Lombardo have found is that most recyclers are using their ECSs to upgrade the nonferrous stream from their shredders and to recover salable nonferrous material from their shredder fluff. A few are even buying their neighbors’ fluff and running that through their ECSs as well.
Although most customers haven’t needed any help fitting an ECS into their operations, they have needed advice as to the sort of environment in which an ECS works best. This is something Henke knows a lot about, and he’s happy to share.
Most importantly, he recommends putting an ECS as far downstream in the process as possible. For best results, the material stream should come through in a single layer of same-sized particles between 1/2 and 5 inches in diameter. If possible, a vibratory feeder should be used.
And, whatever you do, don’t use an ECS to separate ferrous material, Henke says. For one thing, it’s cheaper and more effective to use a ferrous separator. For another, you’ll probably just wind up damaging your ECS.
As for the capacity you can expect from a Steinert ECS, here’s the rule of thumb: With a 20-inch model, you can expect up to 5 tons per hour; with a 40-inch model, up to 10 tons per hour; and with a 60-inch model, up to 15 tons per hour. Of course, this depends on a lot of factors, including the size of the particles, the cleanliness of the stream, and the mode and type of the operation, he points out.
Sticking With Magnets
While new uses for ECSs are constantly being devised, Steinert still is determined to play its hand with due caution and deliberation. As revenues have grown, the company has remained relatively small. Today, it has 80 employees, only 20 more than were on its payroll 20 years ago.
The company also is determined not to get distracted from its strong suit, which is the manufacture of magnet-based equipment for lifting and separating. This is a lesson the company learned years ago, when it lost its shirt trying to branch out into other areas of manufacturing. One of these ventures involved a wheelchair lift for staircases, another a bucket lift for window cleaners. All were disasters.
“We finally stopped playing and stayed with our magnets,” Henke says. “That is our strength now. We are a small and very specialized company. Magnets are our business.”
Just ask, he’ll tell you all about them. If he has the time. •
This German manufacturer of magnetic equipment sees its patented eddy current nonferrous separator as the key to making its mark in the North American market.