The U.S. Department of Energy’s National Energy Technology Laboratory recently awarded West Virginia University a project to survey acid mine drainage solids to identify the concentration and amount of rare earth elements available in AMD solids.
The new project will sample and analyze AMD solids from 120 AMD treatment sites at coal mines across the northern and central Appalachian coal basins in West Virginia, Pennsylvania and Ohio. This follows a February 2016 NETL award to WVU to explore the potential to recover and extract rare earth elements from AMD solids, a project that is currently underway.
Acid mine drainage from pre-law coal mines is a major stream pollutant in the Appalachian region. However, when treated to meet current regulatory requirements, it yields solids that have proven enriched in critical rare earth elements.
“We will work with members of the coal industry and state agencies that are engaged in treating AMD to sample their solids” said Dr. Paul Ziemkiewicz, director of the West Virginia Water Research Institute and principal investigator on the project.
This new effort is in support of the DOE’s ongoing program to recover rare earth elements from coal and coal by-products.
Rare earth elements are vital to the technology industry. These elements have numerous applications and are used in devices such as cell phones, medical equipment and defense applications. Conventional rare earth recovery methods are difficult, expensive and generate large volumes of contaminated waste.
In addition to providing a domestic supply of these critical industrial materials, this approach would incentivize AMD treatment and offset treatment costs while continuing to improve the quality of Appalachian streams.
Appalachian coal mines commonly generate AMD, when sulfide minerals in rock are exposed to air and water. This acid leaches rare earths from coal associated rock where it collects as AMD. Active coal mines are required to treat this AMD, which concentrates and precipitates rare earth elements.
“Together, the rare earths in AMD solids range in value from $45 to $125/kg and our early sampling indicated that AMD solids contain between 0.3 and 1.5 kg of total rare earth elements per ton of AMD solid” said Ziemkiewicz.
Ziemkiewicz, along with co-investigators Xingbo Liu, professor of mechanical engineering, and Aaron Noble, professor of mining engineering, in the Statler College of Engineering and Mineral Resources will estimate the volume of acid mine drainage that is available in the northern and central Appalachian coalfields, as well as the purity and amount of rare earth elements that could be recovered. The research team will be assisted by Ben Faulkner, an independent contractor from Princeton, West Virginia, who has extensive experience with acid mine drainage treatment plants across the Appalachian region.
“Acid mine drainage solids are generated at treatment plants, and Ben’s familiarity with these facilities will be a tremendous asset to the project,” said Ziemkiewicz.