Algae breakthrough could double rare earth concentrations

Researchers at Southern Illinois University in the US have found algae can more than double the concentration of rare earth elements, offering a potential alternative to chemical-intensive processing as the US seeks to strengthen domestic critical mineral supply chains.

With governments racing to secure domestic rare earth supply chains, improving how the metals are concentrated and processed has become as important as finding new deposits. 

Graduate geology student Kristina Kohl said many people still associate rare earths with consumer electronics, overlooking their critical role in defence technologies.”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 dominates the rare earth industry, mining about 60% of global supply while 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.

Researchers are also evaluating 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 failed to reach the surface formed mineral-rich intrusions and deposited additional rare earths in surrounding breccia through hot, mineral-bearing fluids.

The work highlights how previously overlooked deposits could become more attractive if extraction costs and environmental impacts can be reduced.

Cleaner extraction

To test the new extraction method, microbiologist Scott Hamilton-Brehm and his team built a miniature river system using a 50-gallon trough, circulating pumps and LED lighting to simulate flowing water and sunlight. Geologists added finely ground rare earth-bearing rock before introducing microalgae into the water.

Laboratory analysis showed the algae not only absorbed the rare earth elements but increased their concentration by more than twofold through a mechanism researchers do not yet understand.

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

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

Researchers are now testing additional algae species to determine whether they further increase rare earth concentrations and are preparing a proposal to the National Science Foundation to expand the work. Hummer said the project demonstrates the value of interdisciplinary research, bringing together geology and microbiology to address challenges in critical mineral development.