US researchers investigate using biological processes to recover rare earths from waste
Coal ash, red mud, and mine tailings are typically viewed as environmental liabilities, however, locked inside these massive waste streams are valuable silica, rare earth elements (REEs) and other critical minerals.
A Worcester Polytechnic Institute- (WPI-) led research team has received a $3.3-million award from the National Science Foundation’s Growing Convergence Research programme to explore whether lessons from diatoms, sea sponges, and plants could help recover those resources using less energy and fewer harsh chemicals.
WPI is based in Massachusetts, in the US.
The five-year, two-phase project is led by Mingjiang Tao, associate professor in the WPI Department of Civil, Environmental, and Architectural Engineering, with Professors Carrick Eggleston and Yan Wang serving as co-principal investigators.
Researchers from George Mason University, the University of California San Diego, the University of Massachusetts Amherst, and the University at Buffalo will also be involved.
“Recovering critical minerals is only part of the opportunity. We want to develop a process that uses as much of each waste stream as possible, separating strategically important elements while converting the remaining material into useful products. That whole-material approach could fundamentally change how industries manage waste and obtain essential resources,” Tao states.
The research addresses two interconnected challenges: producing many silicon-derived materials used in concrete, glass, ceramics, semiconductors, and silicones can require high temperatures, substantial energy, and intensive chemical processing; while industries also generate enormous quantities of silicon-rich waste, including coal ash residue, red mud, mine tailings, concrete debris, waste glass and metallurgical slag.
Much of this waste is stored in landfills, ponds, impoundments, and large waste piles, even though it contains valuable silicon, critical minerals, and rare earths. For example, the estimated 11-million tons of rare earths trapped in US coal ash landfills is worth $8.4-billion, which is nearly eight times the nation’s current raw domestic reserves.
These materials are essential for electronics, clean-energy technologies, transportation, and national security.
The researchers will look to nature for possible solutions. Diatoms, sea sponges, and certain plants use biological molecules and organic scaffolds to capture dissolved forms of silicon and assemble them into intricate silica structures under relatively mild conditions.
By adapting these mechanisms, the team aims to develop lower-energy methods that break down the silica-rich components of industrial waste, convert the silica into useful materials, and free REEs and other critical minerals trapped within the substances.
The project brings together expertise in biology, geochemistry, materials science, metallurgy, engineering, computational chemistry, and AI.
The researchers will use advanced computational modelling and AI to design specialised biomolecules, predict how those molecules will interact with silicon-rich waste, and accelerate the identification of promising pathways for mineral recovery and materials manufacturing.
As lead principal investigator, Tao will oversee the project’s management and coordination while leading research on biosilicification, the process through which organisms form silica materials, and bio-enabled metallurgy for recovering REEs from silicon-rich wastes.
Eggleston, with his expertise in geochemistry, will, in turn, lead efforts to identify, understand, and optimise the chemical reactions involved in breaking down and rebuilding silicate materials.
His work will examine the pathways and reaction rates associated with silicate dissolution, repolymerisation, carbonation, glass formation, and silicone synthesis.
Wang, who is a widely recognised pioneer in battery recycling and sustainable manufacturing, will lead the development of bioengineered processes for recovering REEs and other critical minerals.
The team will also evaluate the economic and practical feasibility of scaling the technologies for industrial applications.
If successful, the research could create new pathways for transforming large volumes of industrial waste into marketable products, reducing reliance on newly mined resources, lowering the environmental footprint of materials production, and strengthening domestic supplies of critical minerals and REEs.
This project also aims to cultivate a broader bioengineered, silicon-based materials ecosystem by connecting researchers, industry partners, policymakers, educators, and future innovators across disciplines and sectors.