Recycled glass is used in glass, brick and tile manufacturing, but a major roadblock is that the type of glass needed is not often readily (or cheaply) available.

The benefits of using cullet (recycled glass) in a variety of manufacturing processes are well known. According to Joe Cattaneo, president of the Glass Packaging Institute (GPI, www.gpi.org), “Using cullet in the glass making process provides for unmatched production efficiencies and significant environmental benefits, both necessary for a sustainable package.” (Joe’s new column, “Glass Works,” will debut in the October issue of CI.)

Cullet is also used in brick and tile manufacturing, but a major roadblock, according to industry consultant Robert Kirby, is that the type of glass needed is not often readily (or cheaply) available. “The glass comes almost exclusively in the form of dust from the bag houses of large glass processors that generate the dust as a byproduct of processing glass for fiberglass and container manufacturers,” he writes in “A Glass Act” (CI BCR, February 2007). “At most, a few brick manufacturers are using 2% of glass as a raw material, which is not enough to significantly affect either recycling markets or national energy consumption.”

Kirby’s experiments using 12-mesh (and finer) glass in brick clay to accelerate drying and reduce shrinkage proved successful, though he cautions that updated glass recycling equipment and expanded recycling programs may be necessary to make it a cost-effective option for brick manufacturers.

Unfortunately, recycling programs are running into financial roadblocks of their own. According to an article in last week’s Columbus Dispatch (www.columbusdispatch.com), “The market price for recycled glass is so low that it doesn’t make any financial sense for bars and restaurants to recycle the container for the world’s favorite alcoholic beverage.” The good news for manufacturers is that recyclers, faced with low profits, are looking for new markets.

“The recycling industry is searching for good value markets that involve cost-effective processing, as well as local markets for the recycled glass,” write the authors of “Recycled Glass Options for Tile” (CI, October 2007). “Over the last 20 years, many communities have been processing, or simply breaking, their mixed color glass locally and using it as construction fill or daily landfill cover. While these applications can be effective alternatives to disposal, and can help keep collection programs going, they generate no positive cash flow and are not long-term solutions to glass markets.”

We can’t just snap our fingers and make additional applications feasible, however. Manufacturers must study their raw materials and firing processes to see if recycled glass will work for their application(s). New recycling programs, coupled with updated/revamped glass sorting and processing methods, are also necessary. In addition, relationships must be fostered between communities, recyclers and manufacturers before the benefits can be realized.

It’s possible that – with some time and effort – using recycled glass for a number of different applications can become a cost-effective option for many manufacturers. Look for additional information regarding the feasibility of using cullet in manufacturing processes in future issues of CI.

Links to the full text of cited articles are included below.

Links

• "A Glass Act"
• "Costs Make Recycling Glass Bottles a Tough Sell"
• "Recycled Glass Options for Tile"