Extraction and Recovery of Rare Earth Metals from Coal Combustion Products
Coal fly ash has recently been examined as a resource for rare earth elements. One study found that the average REE content for various ashes derived from sources in the Appalachian Basin, Illinois, and the Powder River Basin were 591, 403, and 337 mg/kg, respectively. Additionally, the amount of critical REEs (Nd, Eu, Tb, Dy, Y and Er) in the fly ashes was 34-38% of the total. Since the United States generates approximately 115 million metric tons (mt) of coal combustion products (CCPs) annually, including 45 million mt of fly ash, CCPs could represent a significant domestic supply of REEs.
Periodic Products’ technology addresses the need to improve the extraction and recovery technology of REEs from CCPs by efficiently extracting and recovering a range of valuable REEs from the calcium- and silica-rich CCP matrix.
This Technical Bulletin describes the non-optimized extraction and recovery of rare earth metals from CCPs. It should be noted that the non-optimized extraction and recovery yields for CCPs were similar to the non-optimized yields for phosphate waste products.
Prior to Periodic Products’ technology, an efficient and economically viable low environmental impact process to extract and recover these critical materials from CCPs was not possible. The financial and environmental costs associated with recovering REEs from mining wastes such as CCPs using this technology are significantly less than the costs of obtaining these metals from mined ore. It is estimated that the cost of Periodic Products’ extraction and isolation technology is approximately $6 per kilogram of mixed REEs – approximately 40% of the current cost of mining and isolating these metals.