CWC

Best Practices in Glass Recyling

Processing / Windshields

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Processing Automotive Windshield Glass

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

turnkey 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

Processing / Windshields

Page 2 of 2 BP-GL2-06-01

Contact: For more information about this Best Practice, contact CWC, (206) 443-7746, e-mail

info@cwc.org.

References:

Andela product literature. Andela Tool & Machine, Inc., Richfield Springs, N.Y.

Issue Date / Update: November 1996ins