Researchers Unveil Efficient Method to Recycle Rare Earth Magnets

A team of researchers has developed an innovative method for recycling rare earth elements (REEs) from discarded electronics, particularly focusing on magnets. This new technique promises to significantly reduce energy consumption and environmental impact compared to traditional recycling methods. The findings were published in the Proceedings of the National Academy of Sciences in 2023.

The process involves using an electric current to heat waste magnets rapidly, reaching extremely high temperatures. Chlorine gas is then introduced to react with non-REEs, allowing for the efficient separation of these valuable materials. According to James Tour, a professor of materials science and nanoengineering at Rice University, this method could help the United States meet its increasing demand for REEs. “The country’s scurrying to try to see how we can get these [REEs],” he stated. “And, in our argument, it’s all in our waste… We have it right here, just pull it right back out of the waste.”

Innovative Heating Technique

In a breakthrough in 2018, Tour and his team discovered a process known as flash joule heating, which can convert various carbon sources into graphene. Building on this foundation, the recent research combines flash joule heating with chlorine gas to separate REEs from waste magnets.

The approach begins with grinding waste magnets into a fine powder, which is placed on a carbon platform inside a glass chamber. A current is applied, generating temperatures exceeding thousands of degrees Celsius in seconds. As chlorine gas enters the chamber, it reacts with unwanted elements, creating chlorides that vaporize at lower boiling points than the REEs. For example, while iron’s boiling point is around 3,000° C, iron chloride vaporizes at just 315° C. This allows for efficient separation, with the REEs remaining in oxide or oxychloride form on the carbon platform.

The team achieved a purification level exceeding 90 percent, recovering over 90 percent of the REEs from the waste magnets. Tour noted that this method is versatile and could potentially be applied to other forms of electronic waste.

Environmental and Economic Benefits

The research team conducted a life cycle assessment and techno-economic analysis to compare their process with conventional hydrometallurgical extraction methods, which are often energy-intensive and involve hazardous acids and solvents. Tour described these traditional methods as “messy” and noted that their new approach reduces energy consumption, greenhouse gas emissions, and operating costs by 87 percent, 84 percent, and 54 percent, respectively.

In 2022 alone, the world produced approximately 66.2 million tonnes of electronic waste, much of which harbors a higher concentration of REEs than found naturally in the earth. Unlike plastic, metals are infinitely recyclable, making the recovery of these materials from waste a more sustainable option. Tour emphasized the financial implications, stating, “Setting up a mine is also very expensive. You might as well just get it from waste.”

The team’s findings could significantly impact how rare earth elements are sourced, providing a cleaner and more efficient method of recycling that aligns with growing environmental concerns. As the need for these materials continues to rise, the ability to recover them from waste could pave the way for a more sustainable future.