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Researchers Turn Old Toothpaste Tubes Into Aluminum and Fuel
December 11, 2014
Nestlé, Kraft Foods and Mondelez International are helping fund a new commercial-scale recycling plant that can turn old toothpaste tubes into aluminum and fuel in only three minutes.
This type of plastic-aluminum laminate waste, often used in drink pouches and pet food packaging, typically ends up in the landfill. Each year, around 16,000 tons of aluminum is wasted in the UK alone.
To address this waste problem, researchers at the University of Cambridge have been exploring how laminate packaging would react to intense heating, called microwave-induced pyrolysis.
Particulate carbon is an efficient absorber of microwaves and can transfer this thermal energy to adjacent materials. If the adjacent material is organic, such as plastic or paper, it breaks apart (or pyrolyses) into smaller pieces; if the material is a metal attached to the plastic or paper, the metal can be recovered in a clean form after the attached organics are pyrolyzed.
The researchers put a pile of particulate carbon and some shredded laminate packaging inside a conventional kitchen microwave, replaced the air inside the oven with nitrogen and turned the microwave up to full power until the temperature increased to about 1,112°F. When they opened the door two minutes later, the laminate material had been separated into clean aluminum flakes and hydrocarbon gases and oil.
With funding from Nestle, Kraft Foods and Mondelez, the idea has now been successfully scaled up in the form of a commercial plant which will recycle 2,000 tons of waste a year. The aluminum is used for smelting, while the hydrocarbons are used for fuel with no toxic emissions.
The researchers expect the plant to pay for itself within three years.
In October, aluminum rolling products maker Novelis opened the world's largest aluminum recycling center, located adjacent to the company's rolling mill in Nachterstedt, Germany. The $258 million recycling center will process up to 400,000 metric tons of aluminum scrap annually, turning it back into high-value aluminum ingots to feed the company's European manufacturing network. Earlier this year, Novelis launched the world's first commercial use of evercan™, the company's independently-certified high-recycled content aluminum sheet for beverage cans.