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Processing Gypsum Drywall
for Recycling
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Several
processing methods have been utilized for preparing gypsum drywall for
recycling.
The two major objectives of processing are separation of gypsum from
the
paper and the size reduction of the gypsum itself. A big issue
associated
with drywall processing is dust, and this is addressed by containing as
much
of the processing system as possible (placing indoors) or by providing
water
in the form of a mist to minimize emissions.
Drywall processing
systems
will in many cases require an air permit (appropriate regulatory
authorities
should be contacted - see state
contacts list). |
Standard
waste processing equipment (such as this tub grinder) may be used, but
a screen will typically be required depending on the end-market.
The control of dust is major concern.
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A
common practice is to integrate the grinding operation and the
screening operation.
In some cases, a trommel screen can be used for both size reduction and
separation of gypsum from paper.
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Several vendors market
self-contained
drywall
processing equipment. Many of these operate using some
type of
grinder
followed by a screening system; a dust collection system is typically
included.
Standard size reduction devices found
(e.g.
tub grinders, horizontal mills) at many waste processing sites can be used to process drywall.
Dust
issues may need to be addressed and screening will normally be
necessary. Trommel screens are frequently used screening devices, and in fact,
trommel
screens have been used as stand-alone operations where drywall is both
separated
from the paper and size reduced. The recovery efficiency is not
as
high as obtained in the shredding systems, but a preliminary size
reduction
step such as using a loader or compactor to provide rough size
reduction
is useful for increasing efficiency.
A recent
development is the
use
of small grinders directly at the construction site; the idea is to
apply
size-reduced gypsum directly at the site. See the page on
recycling
drywall at the construction site for more information on the types
of processing equipment used for this application.
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This website was developed
by
the Construction Materials Recycling Association under a grant from the
U.S. EPA Region 5.
© 2003-2010 CMRA. All rights reserved.
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