Register for free to
view the full innovation profile.
Rare Earth Elements are present in a range of sources, including secondary waste streams, yet remain difficult to isolate because of their tendency to form mixtures. Extraction is a highly complex process that can vary significantly between material types and even individual deposits. In traditional mining processes, initial physical separation consumes a high volume of raw materials and produces significant amount of waste in the form of tailings. Follow-up processing to extract the desired metals from mineral concentrates typically requires industrial-grade chemicals and solvents. The resulting hazardous liquid wastes, radionuclides, and heavy metal residues must be carefully managed according to environmental and occupational health standards, adding significant risk and increased costs.
About
Sandia researchers have developed a groundbreaking approach for converting coal ash, a by-product of coal combustion, into a viable domestic source of rare earth elements using just three readily available ingredients: water, supercritical carbon dioxide (scCO2), and food grade citric acid. By combining thermodynamic and DFT modeling and experimental tests, researchers were able to successfully remove target metals from coal and coal ash using these environmentally benign ingredients. The method has been shown to achieve a 42% extraction efficiency and can preferentially extract some of the most critical REEs. In addition to recovering REEs, this method can also remove other heavy metals from coal and coal ash to make cleaner coal before combustion or cleaner coal ash to facilitate its reuse or final disposal.
Key Benefits
Converts coal industry waste into a reliable domestic source of REEs Provides 2x the value of conventional sources and approaches ($ value / mass) Environmentally benign, Provides a greener, lower cost, and domestic REE source
Applications
Recycling and cleaning of coal ash and/or coal combustion residuals Mining and extraction of rare earth elements (REEs) Recycling of other waste sources for extraction of REE