| GRN Recycle Talk FAQ Answer |
Date: Tue, 17 Dec 96 14:56 WET From: FRIEDMAN.FRED@EPAMAIL.EPA.GOV (Fred Friedman) Subject: Re: Recycling glass (Jim O Donnell)
December 17, 1996
Dear Jim O Donnell,
The process for container and noncontainter glass recycling is different, but not very; however each must be recycled differently. From the standpoint of glass manufacture, recycling of each lowers costs, particularly energy costs. Glass containers for example, can be sorted by color and melted down and reformed at a lower temperature than it takes to combine the 3 raw materials from which new glass is made. Melting at a lower temperature also saves wear on furnaces, with additional savings on maintenance and replacement parts, as well as the down-time to change them. Melted cullet is then reshaped by mechanical means to the specifications that the recycled product will have: new bottles, fiberglass, glassphalt (which generally is just crushed glass, not remelted glass), construction uses, will be re-formed differently.
You don t mix colors together because furnaces have reactions to mixed color glass. Green and amber bottles (usually imported) tend to be problemmatic as there are few markets that accept them. Other contaminants ( Vision Ware and ceramics, metals and dirt) must also be separated out.
If you need additional information call the Glass Packaging Institute, Washington, DC at 202-887-4850.
Other studies of recycled applications and the techniques used to remanufacture glass to get there, have been undertaken by the Clean Washington Center at 206-464-7040. They have e.g. used glass as a construction aggregate in a 7/93 study by Dames Moore; they ve used it as a septic treatment filtration medium in 1995, and as a hydroponic growth medium in 1995 with a final report expected out in early 1996.
The best step by step process description of glass recycling is on pages 54-56 of the Recycling Sourcebook ed. by Thomas Cichonski and Karen Hill (Gale Research, 1993). Its the sort of reference book that a large public library or university library supporting an environmental program would have.
I trust that this helps.