Material: Recycled
Glass
Issue: Windshields are manufactured
with two layers of glass with a strong plastic (usually
PVC) membrane sandwiched between the panes.
This structure limits recyclability dramatically.
Plate glass itself is challenging to recycle
because of its different chemical composition from container
glass. Plate
glass and automotive glass can be successfully recycled
into construction aggregate or other secondary markets
if the glass can be separated from the film.
Separating film plastic from windshield glass
requires that the glass be broken adequately to free
the film, while keeping the film in large enough pieces
that it can be removed without fouling equipment.
Best
Practice:
Systems
are now available to crush windshields and screen film
plastic residuals in a turn-key system.
In one system, compression feed rollers are used
to guide windshields through a processing system at
a predetermined rate and physical orientation. The system is 70 inches long, 50 inches wide
and 56 inches high.
The input opening is up to 43 inches and drive
components include a 10 horsepower motor, solid steel
shaft, 40 hammers constructed of flailing arms made
from hardened steel, 2 inch heavy duty isolated bearings,
and two - ten inch compression feed rollers.
Controlled feed is necessary because flexible
impactors are used to flail the glass off the plastic
membrane, while keeping plastic pieces as large as possible
for removal during screening.
A successful removal operation relies on the equipment
configuration and material properties of glass and plastic
to enable pulverization of the constituents so that
the PVC pieces are larger than the glass for separation
in a trommel screen (see Screening Technologies
for Glass Processing Best Practice). One pass through one of these systems separates the PVC from the
glass windshield and pulverizes the glass into a clean,
homogenous product of less than 1/4" in size.
The plastic PVC laminate remains in pieces one-inch
and larger. This system is capable of processing four to
five tons per hour (one windshield every five to ten
seconds).
Implementation: In considering systems to process
automobile windshields, the efficiency of segregation
is critical to whether any marketable product will be
generated. Ease of operation and throughput rates are important as well.
Benefits:
With
effective processing, there is no need for windshield
glass to be a solid waste.
Windshield glass represents a substantial supply
of relatively clean, clear plate glass which has potentially
widespread applications, including aggregate and industrial
minerals applications.
Application
Sites:
Material
Recovery Facilities
Contact: for more information about this Best Practice, contact
CWC mailto:info@cwc.org.
References: Andela Tool
& Machine, Inc., Richfield Springs, N.Y.
Issue Date / Update: November 1996
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