Longevity of Metals

Are you curious about the lifespan of metals and how they are affected by waste management and recycling? Look no further! 

In this article, we explore the different lifetimes of metals, including ferrous and non-ferrous metals, and how losses occur over time. The source is the study by Poncelet et al. titled "Losses and lifetimes of metals in the economy." ¹

You will read about:

• Average lifetimes of metals, ranging from 50 to 150 years depending on type.
• Loss patterns over time, with specialty metals lost quickly and iron lasting the longest.
• Comparison of recycling efficiency indicators like recycled content and EOL-RR.
• The importance of efficient recycling in reducing metal loss rates and increasing recycling rates.

Average Lifetimes

Metals have different lifetimes, ranging from less than a year to nearly two centuries. The use of metals in applications with longer lifespans and high process yields contributes to longer lifetimes. 

The researchers calculated the average lifetimes of different groups of metals by taking into account how much of each metal is extracted each year. This is what they found out:

• Non-ferrous metals (such as copper and aluminum) have an average lifetime of around 50 years.
• Precious metals (like gold and silver) have an average lifetime of around 61 years.
• Ferrous metals (such as iron and steel) have the longest lifetimes, with an average of 150 years.
• Specialty metals (like titanium and cobalt) have shorter lifetimes, ranging from less than a year to 26 years on average.
  

Gold and iron increase the average lifetimes for precious and ferrous metals.

Gold represents a small volume of precious metals extracted but has the longest lifetime. Iron is the most extracted ferrous metal and has a longer lifetime compared to other ferrous metals.

How Metals Are Lost Over Time

Losses of specialty metals occur quickly due to short application lifespans and low collection yields, resulting in high losses in each life-cycle phase. Other metal groups have lower losses during production and use, but losses increase over time as metals undergo multiple life cycles with waste management and recycling.

Iron has the longest lifetime, and a significant amount is expected to be lost to waste management. Non-ferrous and precious metals have lower expected losses in waste management but still experience proportionally greater recycling losses.

In 100 years, half of the total weight of the extracted metals is projected to still be in use, mostly iron, while specialty metals are expected to be completely lost. Approximately 4% of ferrous and 16% of precious and non-ferrous metals are expected to be in use after 100 years, and these percentages decrease after 200 years. Only a small percentage of recently extracted iron and gold is predicted to remain in the economy for 500 years.

Comparison of Loss Rates and Recycling Indicators

These are the two common indicators of how efficient the recycling process is: 

• Recycled content: The proportion of recycled metal in the flow of fabricated metal relative to the total input of metal.
• End-of-life recycling rate (EOL-RR): The percentage of metal in old scraps that is functionally recycled. (New scraps come from manufacturing processes, while old scraps come from end-of-life applications.)
  
  

However, these measures don't tell us the whole story.

Loss rates of metals over time are also crucial for determining efficiency of the process. This is the rate at which extracted metals become unavailable for further use.

• Metals with higher EOL-RR and recycled content tend to have lower loss rates, especially ferrous and precious metals, which are recycled efficiently.
• Metals with low EOL-RR have loss rates that are mainly determined by process yields and the lifespans of applications. Identifying where losses occur helps explain their loss rates.

For example, barium has a negligible EOL-RR and recycled content, but its loss rate is lower than tellurium because it's lost mostly in the use phase. In contrast, tellurium is lost mostly during initial production.

They also have loss rates competing with other well-recycled metals because they're used in long-lived applications.

Boron's loss rate is similar to that of rhodium, despite its negligible EOL-RR and recycled content because it's used mostly in insulation-grade glass for the construction sector, with an average lifespan of 50 years. In contrast, rhodium is used mostly for catalytic converters in vehicle exhaust systems, with shorter lifespans.

The Bottom Line

The lifespan of metals varies greatly depending on the type of metal and its application.

Ferrous and non-ferrous metals have longer lifetimes compared to specialty metals, while gold and iron have the longest lifetimes in their respective groups. Metals are lost over time due to multiple life cycles with waste management and recycling, and losses increase as the metal moves through different phases.

The efficient recycling of metals, especially ferrous and precious metals, can help reduce loss rates and increase the end-of-life recycling rate and recycled content. By understanding where losses occur, we can identify the best strategies for managing waste and recycling metals.

Work Cited

Poncelet, et al. “Losses and lifetimes of metals in the economy.” Nature Sustainability, vol. 5, no. August 2022, 2022, pp. 717–726. nature.com,

https://doi.org/10.1038/s41893-022-00895-8.