The increased sophistication of sensor sorting equipment,
which began as a way to supplement traditional methods of
processing auto shredder output, might qualify it for a more
central role with shreds.
"The X-rays now are actually perceptive enough to remove the
zinc from aluminum. They also separate sheet and tube from die
cast aluminum," according to Dennis Ciccotelli, southeast
regional manager at Steinert US LLC, Erlanger, Ky., which sells
sensor devices made by its parent company in Germany. The
more-common color-based sensors can't handle those
distinctions, he said.
"I believe that one day sensor sorting will replace heavy
media" that distinguish metals by their density, Ciccotelli
said. "It will be much easier to control and maintain."
Even now, some heavy media operators are reducing the strain
on their equipment by using sensors ahead of the intake.
Diverting irrelevant shards holds down the proportion of
unwanted material entering the density sort, Ciccotelli said,
adding that he views density sorting that uses sand flow as a
more resilient technology than the traditional liquid-based
heavy media. "Sand flow is a more manageable process. It
handles small tonnage rates but it's more environmentally
capable and you can contain it," he said. "But you still have
to clean that media, and the media is expensive."
Sensor sorting had problems of scale a few years back, but
these have been dealt with, Ciccotelli said. "For a while we
were really unsure how many tons an hour we could do with a
given system. Could we maintain somewhere between 5 and 10
tonnes an hour and get the high-purity rating of a sand-flow
process? At between 5 and 10 tonnes, we now can get purities
that sand flow and heavy media can get. It isn't 2 tonnes an
hour any more."
Ciccotelli said that Ferrous Processing & Trading Co.,
Detroit, has been planning the installation of recently
acquired XSS X-ray sensor sorting equipment that could perform
the same tasks as its existing sand-flow facility.
Eddy current technology, though around a long time, has
itself been advancing, he said. Coordinating it with magnets
can be effective in sorting aerospace materials. "With the
right magnetic matrix and with an adjustable rotor to match
with the eddy current, high-frequency eddy current can make
very subtle separation of materials," Ciccotelli said,
recalling one buyer of aerospace surplus who was faced with a
goulash of fasteners. "He was separating titanium from aluminum
from stainless using eddy currents." The installation also
deployed magnetized sheets with a neodymium-iron-boron
Steinert US has recently been giving increased attention to
metals recovery from the garbage stream. "One of our very first
sensor sorters in the waste end is in Iowa. The Ames County
plant has an eddy current and a sensor sorter on one of the
lines they used to pick (by hand). This is material that has
not been shredded," Ciccotelli said.
At competitor Wendt Corp., Tonawanda, N.Y., business
development manager Mark Ridall said sensor technology has
matured. The issue is tailoring it to niches that can use it
"From a metallics point of view, you have all the equipment
available to you today that you need to recover almost every
piece of metallic existing in shredder residue. The next things
that will have to come out are glass and plastics," Ridall
said. "Nobody's choosing to do glass because there's no market
for it. I can spend a million dollars for equipment to be a
nice guy, but I'm not going to get any revenue generated by it.
Plastics, on the other hand, you'll see getting removed (from
auto shredder residue) within 12 to 18 months. There's the
beginnings of a marketplace to trade that material."
One hurdle is uncertainty as to whether certain sorts of
plastics will pass muster with environmental regulators as a
manufacturing material. Ridall expects high-density
polyethylene to be the highest-priority plastic in shredder
residue. However, matching requirements will be tricky. "I'm
sure what's being manufactured in Asia has a different polymer
base than what's being manufactured here or in Europe," he
"The entire industry is waiting to see what is learned from
the facility in the United Kingdom," Ridall said, referring to
a facility of California technology developer MBA Polymers Inc.
and British scrapyard group European Metal Recycling Ltd.
(EMR). With MBA and EMR expecting start-up in the third quarter
of this year, feedback is unlikely until mid-2011. "Once there
are some published data with reliable results we all can
digest, then we'll see some movement," Ridall said.
The economic slump was unkind to narrowly delineated sensor
sorts of shredder scrap.
"When the markets fell apart (in late 2008), nonferrous
markets fell through the floor. There was no value in producing
anything more than zorba (mixed shredder nonferrous) and zurik
(a stainless-dominated mixture)," he said. "Even those were
down to 20, 25 cents a pound with little movement. Eighteen
months later, copper is back to over $3 a pound so you've got
more and more people beginning to focus again on creating
higher-quality zorba and higher-quality zurik packages. I think
we are beginning to see a return of stability to the markets. I
think more and more folks will be turning on that advanced
separation equipment, because you'll see a differential. It
will be worth their while to 'scalp' copper (from brasses) or
to produce a higher-quality aluminum or to break down a heavy
metals package into individual metallics."
At major scrapyard chains, "the equipment will do what they
ask of it. They'll make choices on their process, based on what
the end commodity needs to be-for the highest return or to sell
most easily," he said.
By Ridall's chronology, the scrap industry's first use of
sensors for shredder output in around 2000 was to retrieve
stainless steel from the eddy current waste stream. After
magnets have done their work, nearly all shredders have eddy
current systems to separate nonferrous metals from dirt. Eddy
currents also provide the option of creating an adequate
segregation of aluminum from other metals. However, stainless
steel is inert to the electrical eddy current and lands in the
At the turn of the century, stainless steel was a pricing
standout in a largely dismal period for nonferrous, Ridall
said. That provided an opening for marketing some of the early
sensors. "The recoverable metallics (when sensors monitor eddy
current waste) typically are going to run between 3 and 5
percent," he said. "That is not counting insulated copper wire,
which could be another 3 or 4 percent."
The Institute of Scrap Recycling Industries (ISRI), in
categorizing aluminum, assumes that aluminum shredder scrap
emerges either from sortation by eddy current (producing tweak)
or by selective flotation based on density (twitch).
Sensor-delineated aluminum has no pedigree yet.
"I think in time heavy media will become extinct," Ridall
said. "At that point, ISRI will potentially need to create a