Shredder operators are increasingly focusing on recovering ever smaller pieces of metal from the shredder residue, employing new technology and impelled by market forces that encourage the practice.
One key element making the move possible has been improved processing technology, according to Mike Shattuck, recycling market manager for Eriez Magnetics in Erie, Pennsylvania. “Processors want to recover as much metal as possible, but to recover the more elusive fine scrap metal they need more efficient processing equipment,” Shattuck said. “Newer separation equipment helps maximize the recovery of these smaller pieces of metal, increases their profit margins and allows them to reduce the amount of valuable metals going to the landfill.”
Although new technology is helping drive it, there’s more to the story. This is really just the latest chapter in a continuing evolution of shredding that goes back to the beginning of the industry. Until 10 or 15 years ago, most non-ferrous shredder fines measuring less than 1 inch were screened out of shredder residue and sent to landfills. This material constituted as much as 50 percent by weight of shredder output and included as much as 5 percent metal content by weight, according to Didier Haegelsteen, managing director SGM Magnetics, which has U.S. offices in Bradenton, Florida.
As shredder operators sought to become more efficient and maximize revenue from recycled materials, they began separating smaller and smaller fines. Today, for many shredder operators, nonferrous metal fines of .75” to .5” and smaller are the dividing line. This portion makes up most of the weight of shredder residue at this point in processing, but many shredders have not considered it economically viable to further process the residue to recover these fines.
Eddy current separators are one of the technologies that have helped change this viewpoint. With stronger eddy current separators, improved gravity separators and other tools, the nonferrous fines that are recoverable has shrunk to very fine and now micro fine sizes of as small as an eighth inch. “The whole industry is trying to get every last bit of material in there,” said Jason Looman, president of Steinert US in Walton, Kentucky. “This is obviously one of the next steps.”
These micro fines, up to about three eighths inch in size, can represent a third or more of shredder residue by weight and can include heavy metals such as gold, silver, lead and palladium as well as significant amounts of copper, aluminum, nickel, zinc and brass. While many commodity prices are off their peaks right now, prices for some of these nonferrous metals have not dropped as much as ferrous metals. And shredder operators’ desire to recover more nonferrous metals from shredder residue is partly driven by the wish to shelter their bottom lines from the effects of fluctuating and currently depressed market prices for the ferrous materials that have typically been the focus of recovery efforts.
“With the up and down nature of steel prices, they’re looking to stay competitive,” Shattuck said. In order to shelter themselves somewhat from ferrous market instability, he added, operators are trying to find other valuable materials they can extract from shredder residue. “This increases the value of what they’re buying.”
The improvement in recoverable value can be significant. SGM said its micro fines processing line can recover $65 to $90 worth of additional metal per ton of .75” or less-sized shredder residue. Shattuck said the Eriez Rougher Cleaner Scavenger system, designed to process Zorba shredded nonferrous scrap metals, can generate an additional $500,000 in revenue for a typical scrap yard in its first year of operation.
Part of the impetus for developing new technology came from China’s Green Fence operation, which tightened inspections of scrap imports to that country. According to Shattuck, the Rougher Cleaner Scavenger system was developed to maximize the grade and recovery of Zorba and meet Green Fence standards. The Eriez gear boosts material recovery to 98 percent and allows scrap shipments to fit the Green Fence requirements for maximum allowable contaminants, he said.
“As part of Green Fence, China requires imported Zorba to be of a very high grade,” Shattuck says. “The RCS will allow scrap yard operators to sell a premium high–grade Zorba which will be sought not only by the Chinese, but by other countries around the world.”
Better markets for nonferrous fines are another contributing factor. Red and yellow fines, which have been sold almost exclusively to Chinese buyers, now are in demand from American, European and Asian refiners, according to SGM. And having more customers naturally makes it easier for shredder operators to find purchasers of their smaller fines and to get better prices.
The process itself, however, is not simple. Separating out very small fines is a multi-step effort employing several different separating technologies in series. The most basic approach is to screen out pieces larger than three eighths inches, then apply eddy-current separators to separate small nonferrous fines.
Initial screening is typically by gravity sort separators or destoners employing air and vibratory separation. These start the process by sorting nonferrous fines into lower and higher density fractions. One example, the Eriez DensitySort, can recover 70 percent of red metals from nonferrous fines while also collecting clean aluminum materials, according to the company. These nonferrous auto shredder fines typically contain 8 percent to 12 percent red metals, the company says.
SGM sends material through a pair of destoners and screens followed by high frequency eddy-current separators and dynamic sensor separators to complete the process, resulting in fines that are 95 percent metal, the company said. This is followed by processing with dryers to remove moisture content.
Today’s eddy-current separators are significantly improved, according to vendors. New technology in eddy-current separators includes stronger and higher frequency rotors that increase 5 percent to 10 percent more of the desirable fines, Shattuck said. “With that increased frequently on the rotors, you can take out a lot more of the smaller particles,” he explained.
And further improvements from other technologies are on the horizon. Shattuck said electrostatic separators, in particular, hold promise for increasing the amount of saleable metals recoverable from auto shredder fines.
Given the volatile nature of market prices for nonferrous and ferrous metals recovered from shredder residue, shredder operators are understandably cautious about investing in new separation technology. As a result, mostly larger operators are currently implementing the more sophisticated micro-fine recovery systems.
However, Shattuck maintains, most shredders can probably benefit from improved screening of fines followed by eddy-current separation. “You have to have a certain volume, but you don’t have to be a 300 ton-per-hour shredder to do this,” he said.
What is clear is that, for a growing number of shredder operators, the confluence of market forces, regulatory requirements and improved technology is making it increasingly questionable for auto shredders to send very small metal fines to the landfill. “For many years, people would throw the three eighths inch and minus out and say
it’s not worth it,” Shattuck said. “Now it is.”
This new development is a continuation of a trend that has been going on for years as shredder operators try to get smaller and smaller recoverable bits out of auto shredder residue. “That’s what’s driven the evolution,” Shattuck said. “It’s searching to get the last dollar out of the material.”
Published in the April 2015 Edition of American Recycler News