Auto shredder residue recycling
Prototype recovers up to 60 percent
Automobile recyclers have long wondered what to
do with shredder residue, the leftover material
that remains after shredding vehicles and recovering
If research that is underway at
Argonne National Laboratory in
Argonne, Illinois is commercialized,
two potential options for the nation’s
shredder residue would include
turning foam into carpet padding
and transforming the plastics into
“Up to 60 percent of the residue can be recovered
as usable materials,” said
Bassam Jody, group leader of the
energy systems division at the
With most of the shredder residue
currently sent to landfills,
the United States generates around
5 million tons of the leftover
material annually, Jody estimates.
About 30 percent of the material,
by weight, is polymers and 10 percent
is residual metals.
Argonne, funded by the United States Department
of Energy, has spent around $5 million to develop
the process to recycle the residue, Jody estimates.
Although the basic concept was developed more than
15 years ago, the last 5 years have been used to
develop a pilot plant to demonstrate that the recycling
system works, Jody said.
“Based on this work, we are now preparing a full-scale
process design and cost estimate as a possible next
step in achieving commercialization of the technology.”
The separation system is a continuous dry process
that separates the shredder residue – a mixture
of polymers, wood, glass, residual metals, rocks,
sand and dirt.
After removing any oversized material to protect
the equipment, the residue is conveyed to a shredder
to further reduce the size. The residue is then
conveyed to a trommel to separate the bits and pieces.
A magnetic separation chamber recovers the ferrous
metals and an eddy current separator recovers the
The resulting material contains more than 90 percent
of the recycled polymers originally present in the
shredder residue, Jody said. By weight, about 80
percent of this fraction is polymers and contains
more than two dozen different types of polymers.
Since most of these polymers are not compatible
with each other, the second part of the process
uses a wet flotation system that separates the polymers
by selectively floating or sinking the polymers.
Recycling the polymers and residual metals in the
5 million tons of shredder residue produced annually
would save the equivalent of 24 million barrels
of oil a year and would reduce carbon dioxide emissions
by 12 million tons, Jody estimates.
Some of the shredder residue still ends up in a
landfill, however. After all the recyclables are
recovered from the shredder residue during the process,
the remaining material – including dirt, glass,
sand and other in-organics – is sent to a landfill.
“Shredder residue is one of the leading problematic
materials resulting from the recycling process,”
said Charles Ossenkop, chair of the technical advisory
committee for the Automotive Recyclers Association.
The committee monitors recycling issues related
to automotive design, material usage and recycling
techniques for the trade group.
Ossenkop said the trade group’s committee plans
to discuss the economics behind recovering shredder
residue with researchers at Argonne within the next
The biggest hurdle for recycling shredder residue
is the cost, Ossenkop said, noting it is often more
expensive to recycle, transport and remanufacture
recycled material. “Virgin material is cheap enough
that it often doesn’t justify the cost,” he said.
Shredder residue goes beyond automotive recycling.
David Wagger, director of environmental management
at the Institute of Scrap Recycling Industries,
Inc., estimates that 40 percent of shredder residue
derives from end-of-life appliances, with the remaining
60 percent of residue coming from old vehicles.
While most of the shredder residue ends up in landfills,
Wagger expects to see more uses for shredder residue
in the future. He said it would provide additional
value to shredder operations by reducing waste-disposal
costs and increasing product sales.
The economics behind recycling shredder residue
are more favorable in today’s market than in the
past, said Paul Johansen, a technology marketing
consultant with Johansen Marketing Consulting Ltd.,
in Victoria, British Columbia, Canada.
Transportation costs have gone up, tipping fees
at landfills have increased, and shredder operations
do not have enough land to store the shredder residue,
Johansen said. But he said the viability of any
solution for shredder residue will vary by region.
“There are significant differences in distances
to landfills, trucking costs and environmental regulations,”
Johansen said, adding that there are often marketing
challenges involved with introducing new technologies.
“A good new technology can languish for years unless
there is a good plan on how to commercialize it.”