Institute, which has already built a successful pilot plant and
has got the process well on its way to commercialization.
“I want to see every one of these routes be successful in order
to create a domestic supply chain,” Ziemkiewicz says. “Our next
project – the one that we’re just starting now with DOE [the U.S.
Department of Energy], we will build a roughly half-ton-a-year
processing facility, and that will take acid mine drainage and
create a pre-concentrate that we will then turn into a high-grade
mixed rare earth oxide on site.”
In Kentucky, Honaker says the pilot plant built to extract rare
earth elements from coal refuse has also been a success,
demonstrating the production of a highly concentrated rare
earth oxide from refuse with minimal processing cost – and the
processing is not overly complex.
“We pull out the coarse refuse that has the high [concentration
of] rare earths, grind it down to 1 mm, then we heat the material
up to decompose the mineral that contains rare earths, and
then we put it into a leach system using sulfuric acid to extract
the rare earths in solution,” he says. “Then we use a few
stages of selective precipitation, and that’s how we produce the
Honaker says a survey of coal processing plants shows there
are enough REEs in the waste stream of just a fraction of the
coal processing plants currently operating in the US to meet
current demand for REEs.
“I believe that the resource in coal is real,” he says. “We have
proven that you can extract the rare earths and produce a high-
The extraction of REEs from coal ash is the most complex of
the three, but Massachusetts-based Physical Sciences Inc.
has developed a process to accomplish this and has also
developed a pilot-scale project. Research facilities around the
country have been involved in the effort on research to extract
REEs from coal-based sources – both public and private, both
inside and outside of coal-producing regions.
One thing that makes the idea look so promising is the fact
that the processing of waste for REEs can be done as an add-
on to existing processes. With acid mine drainage it’s an add-
on to existing water treatment, which removes the elements
along with pollutants, creating a sludge that can be processed
for recovery of REEs. With coal refuse, it’s an add-on to coal
processing itself – and one potentially capable of accepting
stored waste as well as the current waste stream.