Ramaco Resources secured a five-year permit to mine
coal on a 4549-acre site north of Sheridan, Wyoming. This Brook Mine site is
believed to contain the largest unconventional REE deposit and critical
minerals sources from coal and carbonaceous ore. This could be a boon to
much-needed domestic sources of these minerals since China currently controls
91% of REE refining activity, 87% of oxide separation, and 94% of magnet
production.
The State of Wyoming will provide a $6.1 million energy
grant to support the construction of a pilot-scale processing facility at the
Brook Mine. Construction is planned to begin later this year. In early July, an
economic analysis by the Fluor Corporation announced that the mine was
technologically and economically feasible.
As detailed below in a
technical report by Weir International, the newly permitted mine will mine
Powder River Basin coal and the interburden between coal seams, which consists
of clays, carbonaceous clays, and siltstones. Both the coal and the interburden
are highly enriched in REEs.
6.2
MINERAL DEPOSIT TYPE
The coal seams can contain significant quantities of REEs,
making the coal seams an attractive source for these valuable minerals on an
ash-basis. The REEs are believed to have been incorporated into the coal during
its formation and are found in association with clay minerals and organic
matter in the coal seams. Interburden between the coal seams also contain
elevated levels of REEs, primarily in clays, carbonaceous clays, and siltstones
not necessarily associated with the coal seams.
In exploring REE mineralization at the planned Brook Mine,
a hypothesis has emerged, as proposed by the NETL in collaboration with WEIR
and Ramaco. Notably, various coals within the mine property have REE
concentrations far surpassing those observed in coals worldwide, including
others in the Powder River Basin (PRB).
According to this hypothesis, the concentrated REEs
within the coals may be attributed to the infiltration of fluids through
permeable and porous coal zones (via cleat fracturing) and other carrier beds,
such as sandstones. These fractured zones have been identified in core, but not
mapped and correlated to the highest concentration zones. The fluid flow is
believed to have induced an acidic environment within the coals, due to the
inherent organic concentrations, while transporting dissolved metals in solution.
This is evidenced by the identification of gypsum within the mineralized coal
zones. The REE metals could have precipitated and accumulated within oxide
minerals at coal/clay boundaries, where varying redox conditions and pH
differences facilitated the REEs’ aggregation and high-grading, particularly
the medium and heavy REEs (MREEs and HREEs). The thickness of these high-grade
zones can reach up to eight feet in the cores analyzed (per NETL).
An important component of this hypothesis is establishing
if the mineralization is primary or secondary. It could be possible that the
source of the Medium and Heavy REEs (MREEs and HREEs) could be primary
deposition via airborne particles of volcanic origin, proximal to this
particular peat system, and incorporated into the coals during deposition. The
substantial volume of coal, reaching a thickness of 30-feet in some zones,
certainly implies a dominant airborne input. A comprehensive understanding of
the cleat systems is imperative to substantiate the viability of fluid flow
through coals as carrier beds.
Ore processing at the mine
site will include pretreatment, primary leaching and filtration, secondary
leaching and filtration, impurity removal via precipitation and ion exchange
(IX), rare earth separation via solvent extraction, gallium and germanium
processing, and water supply, management, and utilities.
As noted in the table below,
scandium is expected to bring in the most revenue, nearly 59%, followed
distantly by gallium (about 18%). Together, these two REEs are expected to
bring in 77% of the revenue. The second graph shows China’s current market share
dominance of these two minerals.
Below is some of the minerals
geology, including stratigraphy, drilling program, critical mineral oxide (CMO) concentrations in
the different rock types, and location maps. From fig. 1.2-2 below, we can see that over 88% of the CMOs will come from the 300-500ppm concentration range. That suggests that other U.S. coal seams and spoils with similar or higher concentrations are prospective as well, including those in the Appalachian coal basin.
Below is a table of potential risks, impacts, and strategies for mitigation.
The announcement of permit
approval was met with fanfare as Energy Secretary Chris Wright met at the mine
site with Wyoming’s Senators and Representatives (all GOP). Rep Cyndi Lummis wrote an
opinion piece in The Hill praising the mine permitting, emphasizing it
importance in supplying our critical minerals needs, and stating the importance
that we recover market share from China for mining and processing REEs and
other critical minerals.
References:
Opinion:
Wyoming is leading on critical mineral independence. Sen. Cynthia Lummis
(R-Wyo.), The Hill. July 30, 2025. Opinion:
Wyoming is leading on critical mineral independence
Ramaco
Resources secures five year permit for Brook rare earth mine in Wyoming .Staff
Writer. Mining.com. July 29, 2025. Ramaco
Resources secures five year permit for Brook rare earth mine in Wyoming -
MINING.COM
Ramaco
Resources previews positive PEA for Brook rare earth mine in Wyoming. Staff
Writer. Mining.com. July 1, 2025. Ramaco
Resources previews positive PEA for Brook rare earth mine in Wyoming -
MINING.COM
Building
the Future. Ramaco Resources. Website. Home
- Ramaco Resources
Technical
Report Summary: Brook Mine Property - Rare Earth Element Exploration Target. Prepared
for Ramaco Resources, Inc. Weir International, Inc. May 2025. 6371_BrookMine_TRS_Update-Q1-2025.pdf
Summary
of Brook Mine Rare Earth Project Preliminary Economic Assessment (PEA) Report. Ramaco
Resources. July 9, 2025. Ramaco-PEA-Report-Jul-2025.pdf
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