‘I’m melting, melting’ — environmentally hazardous coal waste diminished by citric acid

Sandia innovation frees rare-earth metals from coal ash for smartphones, computers

In one of nature’s unexpected bounties, a harmless food-grade solvent has been used to extract highly sought rare-earth metals from coal ash, reducing the amount of ash without damaging the environment and at the same time increasing an important national resource.

Coal ash is the unwanted but widely present residue of coal-fired power. Rare-earth metals are used for a variety of high-tech equipment from smartphones to submarines.

The separation method, which uses carbon dioxide, water and food-grade citric acid, is the subject of a Sandia National Laboratories patent application.

“This technique not only recovers rare-earth metals in an environmentally harmless manner but would actually improve environments by reducing the toxicity of coal waste dotting America,” said Guangping Xu, lead Sandia researcher on the project.

“Harmless extraction of rare-earth metals from coal ash not only provides a national source of materials essential for computer chips, smart phones and other high-tech products — including fighter jets and submarines — but also makes the coal ash cleaner and less toxic, enabling its direct reuse as concrete filler or agricultural topsoil,” he said.

The method, if widely adopted, could make coal ash, currently an environmental pariah, into a commercially viable product, Xu said.

Read the complete news release about the environmentally friendly method for mining rare-earth metals.

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