In the movie Sweet Home Alabama, lightning strikes sand on a beach and forms an exotic glass sculpture. This is one of the ways glass can be formed in nature. The lightning is more than hot enough (20,000 C) to melt the silica in the sand. The resulting creations are called fulgurites (right), and, unfortunately for Hollywood, aren't quite the exotic, clear sculptures shown in the movie.
Man-made glass has been around for thousands of years. The oldest known examples are Egyptian glass beads from around 12,000 BC.
Glass is made from silica (found in sand) mixed with chemicals (typically soda ash or limestone) and heated to high temperatures (up to 2800 degrees C). Once it is melted, it can be treated many different ways: poured into molds, blown, pressed - as determined by the final product.
Glass can be melted down and made into new glass an infinite number of times. Using recycled glass reduces the temperature needed to create the new glass, and most industrial glass makers are set up to use significant amounts of cullet (recycled glass). Increasing the use of cullet in a furnace by 10 per cent results in an energy saving of approximately 3 percent, and for every tonne of cullet used, there is a savings of 1.2 tonnes of raw materials.
Because the raw materials (mainly sand) for glass are plentiful and cheap, cullet prices have remained steady and low (hovering around $40/tonne for clear glass) for many years. The price for coloured glass is even lower as most glass bottle makers won't accept coloured glass.
Saskatchewan has one main glass recycler, Potters Industries in Moose Jaw. They grind clear glass into very fine beads, which can be used to add to high-way paint to make it reflective.
The amount of glass in municipal waste streams is decreasing. While 15-20 years ago, glass was typically 6-7% of the waste stream, now it is less than 3%.
Many of the products that used to be packaged in glass have been switched to plastic (when was the last time you saw a glass coke bottle?). Also, as beverage systems moved away from reuse, the glass bottle has became thinner, since it needs to make it through only one use. Glass is still popular for beer, wine, and liquor bottles.
(Source: WasteWatch, March 2003)
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We’ve been making glass, in some form, since 3500 B.C. Its durability is one of the reasons we know we’ve been making glass that long — a few of the shards are still around. Glass is a true ‘cradle-to-cradle’ product, as it can be endlessly recycled into the same high-quality product.
It’s durable, but it’s heavy and breakable. These qualities have led to packaging substitutions away from glass and toward lighter materials like plastic and aseptic containers (e.g. juice boxes). Fewer things packaged in glass mean recyclers have seen less and less glass being collected over the years. Even some of the basic containers that have always been made of glass, like wine bottles, are switching to aseptic containers.
Don’t lose hope, glass aficionados. Consumers view glass as high quality, environmentally friendly and healthy. Recent government actions against polycarbonate plastic baby bottles have caused a resurgence in the demand for their glass counterparts. Glassmaker O-I (formerly Owens-Illinois) has resumed making baby bottles after 20 years at its plant in Charlotte, Michigan.
Another trend toward increased glass use is in the organic food market. Consumers choosing organic options are very concerned about health and about environment. As a result, companies marketing to these consumers are choosing glass for their packaging. Glass is still considered ‘high quality’ and continues to be used for top end products. It is also used as a refillable container, mostly in the beer market.
The glass industry is working on ways to drop the weight of its containers while still maintaining their strength. A UK glass maker, working with the Britain’s Waste and Resources Action Program (WRAP), has produced a 300g wine bottle (the average is 500g with the heaviest at 1.2kg) that is as tough as its heavier counterparts.
O-I (www.o-i.com) is always looking for sources of clean cullet (crushed glass), but the economics of recycling glass (it's heavy, and virgin alternatives are cheap and abundant) mean that the costs of shipping to them get prohibitive quickly.
Consequently, there is no real alternative for bottle-to-bottle glass recycling on the prairies. We have fewer options for glass here and struggle more with trying to recycle it. It’s a problem we have to work on with that good ‘ole prairie ingenuity.
(Source: May 2008 WasteWatch)
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