Four rare earth elements (REEs) recovery projects managed by the US Department of Energy’s (DOE) Office of Fossil Energy and the National Energy Technology Laboratory (NETL) (earlier post) have made significant progress in the development of a domestic supply of REEs from coal and coal by-products by successfully producing REE concentrates.
DOE research has identified coal and coal by-products as a promising domestic source of REEs, which are critical elements in numerous modern technologies spanning a range of applications including electronics, computer and communication systems, transportation, health care, and national defense. An important measure of success for these REE recovery projects is the extracted and separated REE concentration (amount of REEs) in the resulting pre-concentrated, recovered product. The REE recovery percentage (the total amount of the REE present in the feedstock) is critical for the economical processing of these elements.
The primary goal of these NETL-supported projects is to achieve at least 2%—20,000 parts per million (ppm)—REE elemental concentration, which represents a significant enrichment from feedstocks that typically contain REEs at 300 ppm (0.03%). Each of the projects has met or greatly exceeded this goal.
Another project goal is to develop REE recovery processes that are environmentally benign and that will lead to the economic recovery of REEs from coal and coal-based materials for potential future deployment at commercial scale.
NETL said that the four projects, which are currently being implemented and will complete testing by 2020, have achieved impressive results in laboratory and bench-scale experiments, indicating the highest REE concentration percentage achieved to date from coal and coal by-products, as well as the highest associated percentage of REE recovery. The results are as follows:
Physical Sciences, Inc. (pilot-scale project) achieved 40% REE concentration at 15% REE recovery using post-combustion fly ash from burning Central Appalachian Basin coal. Field implementation and testing of physical processing technology will occur in Kentucky, with subsequent chemical processing in Pennsylvania.
The University of Kentucky (pilot-scale project) achieved greater than 80% REE concentration at greater than 75% REE recovery using Central Appalachian Basin and Illinois Basin coal preparation plant refuse. The project team plans to implement and test their technology at multiple field locations in Kentucky.
The University of North Dakota (bench-scale project) achieved 2% REE concentration at 35% REE recovery using North Dakota lignite coal. The University will build and test the technology in their laboratory.
West Virginia University (WVU) (bench-scale project) achieved 5% REE concentration at greater than 90% REE recovery using acid mine drainage solids from the Northern Appalachian and Central Appalachian Basins. WVU plans to build and test their unit in the WVU laboratory.
These projects have led to patent applications for new REE recovery procedures.
Knowledge gained from these four REE recovery projects benefits additional NETL projects currently underway to design technology for producing salable, individual REE compounds from coal-related materials at a minimum rate of 10 pounds per day. The expected purity (concentration) of the REE compounds is a minimum of 90%. Implementation and testing of one or more of these salable REE production projects should be completed by 2020.