Researchers at Southern Illinois University in the United States have found that algae can more than double the concentration of rare earth elements, pointing to a possible alternative to chemical-intensive processing as the US works to reinforce domestic critical mineral supply chains.

The university described the research in an official release: SIU scientists use algae to double the concentration of rare earth elements.

As governments move to secure domestic supplies of rare earths, the ability to concentrate and process the metals has become nearly as important as identifying new deposits. Rare earth elements are a group of 17 metals used in magnets, electronics, energy systems and military equipment, and separating them from surrounding rock can be technically difficult. Rare earth elements are widely associated with consumer electronics, but graduate geology student Kristina Kohl said their role in defence technologies is often underestimated.

“A lot of people think of electronics when it comes to rare earth,” Kohl said. “They don’t realize how big of a role they play in producing equipment for our national defence systems.”

China remains the dominant force in the rare earth industry, mining about 60% of global supply and processing and separating roughly 90%. The US is the second-largest producer, with operations in California and Georgia, and Washington has identified reducing dependence on Chinese supply chains as a national security priority.

The Southern Illinois University researchers are also studying Hicks Dome in Hardin County, Illinois, as a potential domestic source of rare earth elements. Associate professor Daniel Hummer said the site is a crypto volcano, where magma that did not reach the surface created mineral-rich intrusions. Hot, mineral-bearing fluids also deposited additional rare earths in nearby breccia.

The research underscores how deposits that were previously overlooked could become more attractive if extraction costs and environmental impacts can be reduced. It also highlights a broader challenge for US critical minerals policy: domestic supply depends not only on mining, but on finding economical and less waste-intensive ways to concentrate, separate and recover metals from varied sources.

Cleaner extraction

To test the extraction approach, microbiologist Scott Hamilton-Brehm and his team created a miniature river system using a 50-gallon trough, circulating pumps and LED lighting to mimic flowing water and sunlight. Geologists then added finely ground rock containing rare earth elements before introducing microalgae into the water.

Laboratory analysis showed that the algae absorbed the rare earth elements and increased their concentration by more than twofold. Researchers have not yet determined the mechanism behind the result, an important step before the approach can be assessed beyond controlled laboratory conditions.

“When we received the analysis from the state lab, it became evident that the algae did interact with the rare earth,” Hamilton-Brehm said. “We don’t know how. We don’t know why. We’re going to have to figure it out.”

The team subsequently recovered the rare earth elements using a patented process that breaks down the organic material. The remaining algae could potentially be used as agricultural bio-stimulants or processed into biodiesel, adding value while reducing waste.

The method could also reduce dependence on conventional processing techniques that use chemicals such as sulfuric acid to dissolve surrounding minerals. Because rare earth elements are also present in coal ash, mine waste and electronic scrap, researchers said the process may eventually offer a cleaner way to recover critical minerals from secondary sources while helping remediate waste streams.

Researchers are now testing additional algae species to see whether they can further increase rare earth concentrations. They are also preparing a proposal to the National Science Foundation to expand the work. Hummer said the project shows the value of interdisciplinary research by combining geology and microbiology to address challenges in critical mineral development.