Elements that help power everything from the smartphone in your pocket to the nation's
missile guidance system could come from an unlikely Appalachian source — acid
mine drainage sludge.
A team at West Virginia University, led by Paul Ziemkiewicz, director of the West
Virginia Water Research Institute, is studying the occurrence of rare earth elements
at 120 acid mine drainage treatment sites throughout West Virginia, Pennsylvania
These rare earth metals consist of the 17 chemically similar elements at the bottom
of the periodic table, such as cerium and scandium. Despite their name, they’re
not “rare” because they’re often found in other minerals, within the earth’s crust
or, in this case, in coal and coal byproducts.
Yet the U.S. imports nearly all of its rare earth elements. China produces about
83 percent of the world’s rare earth elements used in modern technologies such
as phones, batteries, TVs and medical and defense applications.
The reason the U.S. hasn't tapped into this market is because the processing
of rare earths is considered cumbersome, costly and energy intensive. Conventional
extraction efforts involve grinding through masses of rock and disturbing undeveloped
But in recent years, Ziemkiewicz identified the potential of extracting rare earths
from acid mine drainage after he analyzed old data sets from the U.S. Geological
Acid mine drainage is the outflow of acidic water from a mine. Federal and state
law requires that it be treated prior to discharge to a stream.
Ziemkiewicz noticed high concentrations of the metals coming out of the mines but
none in the treated effluent, which is the water discharged to a stream. That meant
that the rare earths are concentrated in the treatment sludge, which is the solid
material from the raw acid mine drainage.
“In other words, we found a natural process for concentrating rare earth metals,”
The U.S. currently has no active rare earth mines. So last year the Department of
Energy’s National Energy Technology Laboratory solicited ideas for extracting these
elements from coal and related byproducts. The WVU team focused on the solid residues
left over after acidic coal mine drainage.
Obtaining rare earths this way eliminates any additional environmental risks and
monetary costs that would occur with conventional extraction methods.
“The coal market may fluctuate over time, but acid mine drainage will be constant,”
Ziemkiewicz said. “Long after mining is done, there will still be acid-generating
coal mines. In fact, some of our richest rare earth concentrations have come from
sites where mining ceased 30 years ago.”
Larger concentrations of rare earths are present in the northern and central Appalachian
coalfields, which contain more acid mine drainage and are where WVU researchers
are collecting samples.
Development of refining methods is under way at the labs of co-investigators
Xingbo Liu and Aaron Noble, of the WVU Benjamin M. Statler College of Engineering
and Mineral Resources.
“I see a future where abandoned mine sites could be acquired by commercial enterprises
and managed as rare earth production facilities,” Ziemkiewicz said.
The goal of the current project is to identify what the processing costs would look
like. WVU researchers are partnering with the U.S. Department of Energy National
Energy Technology Laboratory, members of the coal industry and the West Virginia
Department of Environmental Protection.
“The support we’ve received has been tremendous and if this all works out, we'll
turn an environmental liability into an economic opportunity,” Ziemkiewicz said.
In West Virginia and Pennsylvania, it is estimated that acid mine drainage could
produce more than 45,000 tons of total rare earth elements per year, or about
three times the current U.S. demand.
Ziemkiewicz hopes his team’s research can ramp up U.S. involvement in the rare earths
market. He believes it could help boost the economies of communities affected by
the decline of coal.
“In many distressed communities where coal mines have shut down, you have acid mine
drainage sites,” he said. “Some of these distressed towns could have rare earth
extraction plants. Plus, you’re creating a domestic source for something that's
otherwise imported. That creates better value for the nation and the consumer.”