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—View
a list of manufacturers at the bottom of the page
At the heart of every ferrous
recycling installation, a shredder labors away reducing
sheets, bars and blocks of steel and iron into more easily
managed strips and chunks. Automobiles, white goods, mattresses
and many other recyclable items are dealt with by ferrous
shredders, densifying the metal for easy hauling or reducing
it for additional processing. High prices for both fuel
and scrap are driving solid demand for ferrous shredders
for clients from scrap yards to automakers.
 Shredders
come in two main varieties. High-speed, high-horsepower
hammermills are favored by auto shredders and others for
their ability to process large volumes of heavy steel and
iron objects. They pound materials destined for recycling
into bits, using club-studded shafts rotating at around
1,000 rpm to crush input against the sides of steel drums
until particles fit through a sized grate.
Low-speed, high-torque
shear shredders typically operating at 30 rpm or slower
pull and cut apart materials using knives mounted on electrically
or hydraulically rotated shafts. While not as frequently
used for shredding automobiles, shear shredders excel as
low-horsepower solutions for shredding steel drums, filing
cabinets and metal turnings.
Metso Texas Shredder’s
high-speed hammermills are primarily used for automobile
recycling, according to Jim Schwartz, technology and international
sales liaison for the San Antonio-based company. Metso Texas
also sells into applications for handling steel logs and
miscellaneous scrap, at rates from 30 tons to 350 tons per
hour. 
Metso models are denominated
according to hammer diameter multiplied by rotor width and
range from 60 x 80 to 122 x 108. Primary drive electric
motors vary from 1,000 to 10,000 horsepower. Metso’s
computer-controlled water injection system reduces smoke,
dust and overall pollution while reducing the danger of
fire in the rapidly spinning mill.
Metso Texas Shredder resulted
from the combination last year of Texas Shredder with a
unit of Finland-based Metso Corp. Schwartz, formerly a principal
of Texas Shredder, says demand is strong from scrap companies
and steel companies with their own scrap operations. “Because
scrap prices were low for several years, there was apparently
pent-up demand,” he says.
Shred Pax Inc.’s
low-speed, high-torque shear shredders utilize two shafts
bristling with knives and rotating in opposite directions.
Direct drive motors range from 5 to 10 horsepower for the
AZ-7, used for shredding metal turnings, to up to 100 horsepower
for the AZ 160 and AZ 200, suitable for car bodies.
Pieper says Shred Pax machines
are in size reduction applications from recycling to manufacturing.
“Business is strong,” says Pieper. “If
it continues the way it started, we’re off to one
of our best years in the last couple.”
 Twin-shaft
shredders from Shred-Tech of Cambridge, Ontario, may employ
electric or hydraulic power trains. Hydraulic shredders
shine at handling jams, says Sean Richter, senior technical
salesman. “It allows the machine to slow to almost
zero rpm to cut through tougher materials,” Richter
says. Shred-Tech’s ST models used in ferrous shredding
applications go from 600 horsepower to 1,200 horsepower.
In recent years Shred-Tech
introduced an offset hex knife configuration to reduce load
on the machines while also allowing processing of larger
materials. Machines have gotten larger. Until fairly recently,
the largest was the ST-500, with an 8-inch hex-shaped shaft
driving 235,000 lbs. of cutting force. “Then for a
magnesium application a few years back we designed the ST-1200,”
says Richter. That model’s 10 7/8-inch shaft produces
300,000 of cutting force. “It allows you to reduce
bigger products, multiple layers and nested products,”
Richter says.
SSI Shredding Systems Inc.
of Wilsonville, Oregon, produces both twin- and four-shaft
low-speed shredders. Most applications are for mixed-waste
streams that include ferrous content, such as turnings and
other manufacturing byproduct, file cabinets and fork lift
battery casings. “The advantage of shredding is to
improve material handling and facilitate further recycling,”
says Dave Wilson, technical salesman.
 SSI’s
twin-shaft models, ranging from the 30 horsepower M55 to
the 600 horsepower M160 are suitable for white goods, cast
metal, mattresses and the like. Cutting chambers vary from
23 inches by 31 inches to 64 inches by 101 inches. Hopper
openings go from 42 inches by 51 inches to 94 inches by
144 inches.
SSI’s four-shaft
Quad system is a recent introduction. Quad models come in
configurations of power, cutting chamber and hopper size
similar to the company’s twin-shaft models.
Wilson says the Quad’s
four close-tolerance cutting disk-equipped shafts allows
more control over particle size. Twin-shaft shredders typically
produce long strips, which make it difficult to separate
materials for further processing, Wilson says.
“With the SSI Quad
shredder it is possible to shred a mixed waste stream that
contains ferrous, non-ferrous, fabric, plastic, etc. and
produce a uniform particle size with one machine in one
step using desirable low-speed technology,” he says.
Whether they produce hammermills
or shear shredders, no matter what the features and technology,
manufacturers all report strong demand for ferrous shredding
applications. “Probably the biggest thing in the market
is steel price,” says Shred Pax’s Pieper. “With
steel prices doing what they are, the steel industry is
looking for shredders. The phone’s starting to ring
with people asking what do you have and what can I get quickly.”
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