The short life of metals

Metals may form the basis of the modern economy, but that doesn’t mean their life is limitless. A recent study has analyzed the useful life of 61 metals in commercial use and has concluded that more than half last less than 10 years. The work, published on May 19 in Nature Sustainabilityalso shows that most of these metals end up being disposed of as scrap or lost in large quantities, instead of being recycled or reused.

Billions of tons of metals are mined every year, and metallurgical production causes about 8 percent of global greenhouse gas emissions. Therefore, recycling more metals would reduce their environmental impact, says Christoph Helbig, an industrial ecologist at the University of Bayreuth and co-author of the study.

“The longer we use the metals, the less we have to extract,” says Helbig. “But in order to figure out how to close their life cycles, we first need to analyze them.”

That the economy suffers due to the great loss of industrial metals is a proven fact, says Thomas Graedel, an industrial ecologist at Yale University. Losses can occur at any stage in the life of a metal. Some are obtained as by-products in mining operations, but are never used; Others are lost through use, when a component or machine breaks down, or they turn into substances that end up being dispersed in the environment, such as fertilizers. However, the study found that 84 percent of the world’s cumulative metal loss is related to waste and recycling (when metals end their lives in landfills or recycling plants).

Until now, most studies trying to quantify these losses have focused on individual metals, but have not looked at the big picture, Graedel stresses. Helbig and his collaborators collected and compared data from different industries to determine how long different metals were useful, how they were lost, and to what extent they were recycled.

The researchers found that, in many cases, only a small proportion is recycled. Some exceptions are gold, which has been in use for centuries and can be reused many times, iron and lead. In contrast, other metals considered “critical” by the European Union and the United States have high loss rates and low recycling rates. These include cobalt, a key component of aircraft engines and lithium-ion batteries, and gallium, which plays a key role in semiconductors used in mobile phones and other devices.

One way to boost recycling would be to force new products to be made from reused metal, suggests Helbig. For example, the European Union is studying the possibility of requiring that some types of batteries be made from recycled lithium, nickel, cobalt and lead.

Recycling alloys (mixtures of two or more metals) can be technologically and economically challenging, says Philip Nuss, an industrial ecologist at the German Environment Agency in Dessau-Roßlau. But giving metals a second, third, or even fourth life is essential to establishing sustainable economies, Helbig concludes.

freda kreier

Article translated and adapted by Research and Science with permission from Nature.

Reference: “Losses and lifetimes of metals in the economy». Alexandre Charpentier Poncelet et al. in Nature Sustainability, May 19, 2022.


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