Rare Earth Element Enrichment from Mining Wastewater Streams

Water scarcity and pollution is of global concern. Industrial and mining operations are among largest users of water and one of the largest polluters. Wastewater produced by the mineral and coal industry is an environmental concern due to its total suspended and dissolved solids. So far, this wastewater has been treated as waste. However, such wastewater, on the other hand, contains critical elements such as rare earth elements. Rare earth elements (REE) are vital to the U.S. as they are essential to modern technologies, ranging from electronics and energy conversion to health care and national defense. The demands for these REEs have surged over the past two decades. China is the principal supplier of REEs to the world; 72% of U.S. imported REE comes directly from China and many REE imports from other countries ultimately originated in China as well. This scenario leads to a high risk of supply shortage in the U.S. Therefore, the U.S. would benefit from domestic secondary sources including waste streams of coal and mineral industry. 

The primary objective of this project is developing a high-performance, low-cost and environmentally benign integrated process to treat coalmine wastewaters to meet the water standards for industrial and agricultural application while recovering REEs as byproducts. For this purpose, a REE selective precipitant will be explored for separation and preconcentration of REEs during the wastewater treatment process. The pre-concentrated REEs will be then purified using a novel mixed-matrix membrane technology. The project for the Seed Grant will start from feedstocks in Pennsylvania which are well-known for their elevated REE content and will eventually focus on coupling recycling critical elements and purifying water on a national scale.