— 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.