Various chemicals build up in the material as it's recycled

Mar 6, 2012 13:34 GMT  ·  By
Eliminating impurities that accumulate in aluminum could enable the material to pass through more recycling cycles
   Eliminating impurities that accumulate in aluminum could enable the material to pass through more recycling cycles

While recycling aluminum beats processing the raw ore needed to produce the alloy ever day of the week, experts draw attention to the fact that repeated recycling of various products made out of the stuff leads to impurities building up within.

On average, it's between 9 and 18 times more energy-efficient to recycle an aluminum object than to produce the same amount of aluminum from ore. But these positive offsets may be negated by the fact that repeated recycling cycles lead to the accumulation of impurities within the material.

Researchers at the Massachusetts Institute of Technology (MIT), in Cambridge, believe that applying a few easy steps to the recycling process may result in stopping this accumulation effect altogether.

If not, the approach could at least be effective for maintaining impurity levels in the processed material to acceptable levels. The idea here is to prevent the structural failure of objects made up of the recycled aluminum.

Official statistics from the United States indicate that nearly 50 percent of the material used in the country is recycled. This has been proudly advertised by green activists, who showed that it's indeed possible to reduce energy and natural resource waste by recycling various products.

A recent study revealed that paint and labels are oftentimes processed with discarded aluminum items, and then incorporated into the finished product. After repeating this cycle several times, the amount of impurities in the material grows exponentially.

By intervening during the sorting process, or when the collected materials are being molten, it may be possible to eliminate this issue, or at least prevent it from degenerating, the science group believes.

The team was led by MIT Materials Systems Lab researchers Randolph Kirchain and Elsa Olivetti, who worked together with colleague Gabrielle Gaustad, from the Rochester Institute of Technology. The study appears in the latest issue of the journal Resources, Conservation and Recycling.

“Developing methodologies to increase the use of ever-decreasing quality scrap is of major importance to the industry. Even as important is the development of tools to make the right decisions regarding implementation of these technologies,” says David Leon.

The expert, an engineer with the Casting Technology Division at Alcoa Technology, was not a part of the team that conducted this investigation.