Shredder operators are taking some high-tech steps
to improve the quality of their shredded scrap.
The first is the Gamma-Tech Crossbelt Metal
Analyzer, which has nothing to do with the actual tearing apart
of metals. It's a process control device-an inspection machine
that tells the shredder's operator what percentage of copper is
mixed or alloyed with the ferrous metals.
Copper is a metallurgical problem for steelmakers,
especially those producing flat-rolled steel. Copper hardens
the steel, making it more difficult to shape and form into
parts for automobiles and appliances.
The Gamma-Tech, installed below the conveyor line,
uses a radioactive isotope that bombards the scrap with
neutrons and looks at the chemical composition of the shredded
scrap in a set of detectors above the conveyor, according to
Joseph Pflaum, president of Gamma-Tech LLC and one of the
developers of the analyzer.
By shooting a beam through the shredded material,
the analyzer sees not only loose copper in the form of motors,
wires and tubing, but also copper that is alloyed to the steel,
The analyzer was introduced to the scrap industry
about six years ago and has gained a number of advocates among
industry managers. Pflaum, a metallurgist, said the technology
has been used since the mid-1980s in the coal and cement
industries. He was first introduced to it in the past decade
when he worked for David J. Joseph Co. (DJJ). At that time, he
was looking for something to give an analysis-any kind of
analysis-of the metal.
DJJ's River Metals Recycling LLC was the first to
install a Gamma-Tech analyzer at its shredder in Newport, Ky.,
in 2002 and has since installed analyzers at its shredders in
Louisville and Henderson, Ky. Trademark Metals Recycling LLC,
another DJJ company, installed an online bulk analyzer at its
shredder in Tampa, Fla., in 2005. Sims Metal Management Ltd.
also has added Gamma-Tech analyzers to several of its
The analyzer allows both shredder operators and
steel mills to detect just how much copper is in the shredded.
The mills, in determining whether they are using obsolete scrap
efficiently, might have to dilute it with the addition of iron
ore-based substitute materials, such as pig iron or
Another step aimed at producing higher-quality
shredded sounds more like a simple change in operating
practices, but it also includes some new technological
Full-box shredding is designed to both increase the
density of the shredded steel scrap and separate more of the
nonferrous metals from the ferrous material, said Tim Conway,
vice president of business development at San Antonio,
Texas-based scrap equipment maker Metso Recycling North
While shredding of vehicles can tear them apart
into fist-sized pieces of metal, Conway said some of those
pieces can be two feet long and have chunks of nonferrous
metals attached. "By shredding components and trimmings into a
smaller, more dense package, we tend to clean up the scrap
better," he said.
The concept calls for keeping the shredder box, the
heart of the shredder, as full as possible so that not only the
hammers but also the pieces of shredded metal work to break the
material into smaller pieces.
Many shredder equipment makers and component
suppliers have promoted the concept of full-box shredding, but
Conway believes Metso "has a leg up" on its rivals.
"(Our) auto pilot drives full-box shredding.
Everyone in the market has copied this but none have truly
understood that it's not just a function of trying to equalize
the shredding on the shredding motor. It's more a function of
being able to understand how full the box is," he said. "So if
you're shredding based on the amperage of the motor and the
peak load is, say, 600 amps .?.?. full-box shredding may mean
you want to run at 800 or 900 amps for a while to get the box
By breaking the metal into smaller prices, full-box
shredding separates more of the nonferrous from the ferrous,
thus cleaning up the ferrous portion and enabling the
air-separation systems and other downstream equipment to
recover the more-valuable nonferrous metals.
Full-box shredding doesn't mean shredder operators
have to pile cars on top of each other and feed them into the
machine's maw. It requires the operators to have the ability to
control the shredder plant, not just running out and turning it
off but being able to compensate for feeds and speeds, he
Smaller, older shredders might be hard-pressed to
adopt the full-box shredding technology because they have few
process controls, but the operators of the bigger heavy-duty
and megashredder models can avail themselves of its benefits,
"It's not counter-intuitive to the shredding
operations," he said. "If they are bigger shedders, they have
more horsepower. Just because it is a bigger shredder and more
horsepower doesn't change the philosophy of properly