The crafty chemist

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Jul 8

How A Used Bottle Becomes A New Bottle

To isolate the glass, a magnet first pulls out metal caps, lids, small tin cans, and other pieces of metal. Today, recycling plants use optical sorting machines. These machines take pictures of all the glass, and then use air jets to blow the clear glass onto a different conveyor belt.

The recycling plant sells the crushed clear glass to bottle manufacturers, like Ardagh Group in Salem, N.J. When we visited, they were making Snapple bottles, Mason jars and Nantucket Nectar bottles. Gary Shears, the general manager, says that they use about 150 tons of clear recycled glass a day.

The recycled glass is mixed with soda ash, sand and limestone, and everything is melted together in a furnace heated to 2,700 degrees.

Shears says they can never get enough recycled glass. Recycled glass melts at a lower temperature than the raw materials used to make glass from scratch. So more recycled glass means huge energy savings. Right now, his bottles are made of about 20-25 percent recycled glass. Shears said he would use two or three times as much, if there was more recycled glass available.

The bright orange molten glass is weighed and cut into pieces called gobs, which are dropped onto molds to create the mouth of the bottles.

Then a glass-blowing machine blows the gobs of molten glass into red-hot bottles. Salem’s newer machines can make about 400 bottles a minute.

(Source: NPR)