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A team of researchers at Rice University has developed a faster and cleaner method for recovering aluminum and removing toxic metals from bauxite residue, or red mud, which is a hazardous by-product of aluminum production.

This new technique, in ACS Applied Materials and Interfaces, involves a brief electrical pulse lasting under one minute, along with a small amount of chlorine gas. If implemented on a larger scale, it could revolutionize global waste management and materials recovery.

The process uses flash joule heating (FJH), which rapidly heats materials with a short, high-power electrical pulse to vaporize harmful metals, leaving behind a residue rich in aluminum. This aluminum-rich material can then be repurposed into durable ceramic tiles or bricks or resubjected to the normal aluminum production process. The method offers a practical and scalable solution to address a significant pollution problem by transforming it into valuable materials, marking an advancement in industrial waste recovery.

"Our research presents a potential game-changing solution for the red mud crisis," said James Tour, the T.T. and W.F. Chao Professor of Chemistry, professor of materials science and nanoengineering and the study's corresponding author. "This advance is massive from an industrial perspective, turning what was once a toxic liability into a valuable asset in under one minute."

Turning toxic waste into tiles

Each year, millions of tons of red mud accumulate as toxic waste from aluminum production, which contains harmful metals. Disasters related to its storage have caused river contamination and flooding in affected communities. The researchers aimed to explore whether this waste could be repurposed rather than merely contained.

The FJH method works by delivering electricity in a flash, similar to a bolt of lightning, while simultaneously introducing chlorine gas. This approach selectively vaporizes iron and other toxic metals, leaving behind the aluminum.

"The speed and simplicity of this method set it apart," said Qiming Liu, a postdoctoral researcher at Rice and a co-first author of the study. "In just 60 seconds, we extracted 96% of the iron and nearly all the toxic species, while retaining almost all the aluminum."

This process is significantly faster and cleaner than traditional methods, which often require prolonged heating in furnaces or the use of corrosive chemicals. The new method uses no water and no solvents while also removing the sodium salts in the process, relieving the end use of the typically caustic red mud.

A promising route to sustainability

This method could benefit industries dealing with other high-volume waste streams such as steel manufacturing, mining and rare earth processing, said Shichen Xu, a postdoctoral researcher at Rice and co-first author of the study.

"What was once an environmental threat can now be transformed into building materials," Xu said. "We have turned cleaned red mud into ceramics that are super-hard, making them suitable for construction and aluminum recovery."

The approach offers a threefold advantage: reducing waste piles, cutting greenhouse gas emissions and decreasing the need for new bauxite mining. For communities affected by red mud disasters, this development signifies renewed hope through applied science.

"This is not just about red mud; it's about changing our perspective on waste," Tour said. "If we can apply this method to other industrial residues, it could represent the beginning of a new era in sustainable materials recovery."

The process, Tour said, is being scaled by the Rice spinoff company, Flash Metals U.S., a division of Metallium Ltd., and deployed in partnership with aluminum production companies around the world.