An NETL-managed project is making impressive progress toward developing a state-of-the-art facility to produce a domestic supply of valuable mixed rare earth compounds from coal and coal byproducts.
Fifteen lanthanide elements within the periodic table, including scandium and yttrium, are referred to as rare earth elements (REEs). They are essential components in many modern technologies — including cell phones, medical devices and national defense systems — yet challenging to extract, with China providing the bulk of the world’s supply.
NETL is aggressively pursuing collaborative projects aimed at developing technologies capable of producing a domestic supply of high-purity, salable rare earth compounds from coal and coal byproducts by 2020. Ongoing work with the University of Kentucky (UK) focuses on Central Appalachian and Illinois Basin bituminous coal preparation plant refuse, which consists of low-quality coal, rock, clay and other waste materials that are sorted out during coal processing.
In laboratory experiments, UK achieved mixed rare earth compounds comprising more than 80 percent REEs — the highest concentration achieved to date — while recovering greater than 75 percent of contained rare earths. Now, researchers are working to develop and optimize an automated pilot-scale facility that will produce up to 0.1 pound of rare earths per hour at that same concentration.
UK’s process involves sorting and grinding the refuse materials to expose greater surface area, which allows mixed rare earths to be more easily extracted. Any remaining coal is removed, and materials containing rare earths move on to a multi-step process that employs physical and chemical methods to recover rare earth compounds, which could be further processed to extract pure metals.
The UK facility is designed to process either liquid or solid refuse. Researchers are currently working to optimize the extraction system using aqueous coal refuse drainage before tackling solid feedstock. UK achieved its 80-percent concentration using aqueous materials in a laboratory setting.
UK anticipates moving on to processing solid coal refuse this month, at which point researchers will repeat the challenging process of optimizing system operations. The four-year project is slated to run through March 31, 2020, with the U.S. Department of Energy investing about $7 million and UK investing about $1.8 million.
This emerging technology developed by UK in collaboration with NETL is expected to develop a revenue stream for waste byproducts from coal while promoting responsible stewardship of the environment. Developing an effective and efficient method for extracting rare earths from coal-based materials will also enhance national security by boosting America’s energy independence.