Researchers Develop a More Sustainable Method of Recycling Metal From E-Waste


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A team of researchers has developed a more sustainable and affordable way to recycle metal found in electronic waste.
Researchers used electrothermal chlorination, or flash Joule heating (FJH), and carbochlorination to save several metals from e-waste by heating a material with an electric current. They published their findings in the journal Nature Chemical Engineering.
The team used a programmable current that could control temperatures from room temperature to 2,400 degrees Celsius that allows for free energy formation of metal chlorides. As explained in the study, “Once conversion to a specific metal chloride is achieved, that compound distills from the mixture in seconds. This allows both thermodynamic and kinetic selectivity for desired metals with minimization of impurities.”
This process allowed the researchers to collect multiple different metals, including tantalum sourced from capacitors, gallium from diodes and indium from old solar conductive film. Not only were the researchers able to extract these valuable metals from old electronic parts, but they also had a yield of more than 85% and metal purity levels of more than 95%.
Current methods of extracting metals from e-waste, such as hydrometallurgy and pyrometallurgy, are less sustainable. While hydrometallurgy has become more popular over pyrometallurgy because it is considered less energy-intensive, it is still water-intensive, Assembly reported. Further, both processes can produce waste and require a lot of acid to complete, Rice University reported.
The researchers believe their development could provide a method that requires less energy, produces less waste and emissions, and recovers more metal.
While researchers successfully collected certain metals in the study, they noted that this process has the potential to extract other critical materials from waste, such as lithium or rare Earth elements.
“We are trying to adapt this method for recovery of other critical metals from waste streams,” Bing Deng, current assistant professor at Tsinghua University and co-first author of the study, said in a statement.
The newly developed method could minimize the greenhouse gas emissions and environmental destruction associated with mining. With the rise in demand for electric vehicles and renewable energy, there has also been a rise in deep-sea mining and extractions for the metals needed for these technologies.
“This breakthrough addresses the pressing issue of critical metal shortages and negative environmental impacts while economically incentivizing recycling industries on a global scale with a more efficient recovery process,” said Shichen Xu, a postdoctoral researcher at Rice University and co-first author of the study.
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