Rare Earth Elements: A Review of Production, Processing ...

Rare Earth Elements Review
Section 3 – Life-Cycle Stages of Rare Earth Elements Mines
drilling mud) as a drilling fluid to entrain and carry the cuttings to the surface while cooling the drill bit.
Often, only water is used as a drilling fluid during exploration since clay drilling muds have the potential
to complicate the petrologic and geochemical analyses; however, formation characteristics and the local
hydrogeology may make drilling with muds or other additives necessary. Other rotary drills use
compressed air to force the cuttings to the surface and keep the drill bit cool. Polymers, oils, or other
synthetics are added to water or air flows to enhance the operational properties of the drilling mud or air,
if needed. Prior to use, the drilling muds do not generally represent an environmental hazard and are
either inert or break down quickly.
When the borehole intersects groundwater, the water can entrain materials from the borehold and
transport those materials to the surface. The potential toxicity of these materials depend on the
composition of any drilling fluids used and materials swept from the subsurface. These formation fluids
can be highly mineralized, and the cuttings and drilling muds can entrain toxic levels of metals and other
chemicals. Drill cuttings and drilling fluids are typically collected once the borehole is completed and
abandoned; however, regulations in some states allow return of cuttings to the borehole. Excess materials
may be stored in drums, contained in mud pits, or managed and disposed of as a waste.
Locations in the United States with Recent Exploration Activity and a Summary of Potential REE
Resource Areas
Potential sites of REE resources have been under evaluation in recent years to prove the reserves and
determine the mining potential at these locations. Sites receiving current or recent attention are located in
Utah, Colorado, Wyoming, Alaska, California, Nevada, and Nebraska.
• During 2008, the Great Western Minerals Group, Ltd. completed an extensive drilling and
sampling program at the Deep Sands deposit located in the Snake Valley and adjacent to the Deep
Creek Mountains of west-central Utah. After a feasibility study to consider the low-grade
monazite mineral ore containing rare earth concentrations, the company announced that it did not
currently plan to undertake additional exploration at the site (Great Western Minerals Group,
2011).
• A recently formed company, Colorado Rare Earths Incorporated (CREI), announced in March of
2011 that it was soliciting funding to begin exploration near the Powderhorn mine site in
Colorado (Colorado Rare Earths, Inc, 2011). CREI also has acquired properties at Iron Hill and
Wet Mountains Colorado, where potential REE resources have been identified. CREI is currently
organized as a mineral claims acquisition company, but plans to expand to an exploration and
development company in the future.
• In Alaska, exploration is underway at the Bokan Mountain site that is located at the southernmost
end of the Alaskan panhandle on Prince of Wales Island. This is a site that was mined in the
past for uranium ore, but also has known HREE and LREE resources.
• Molycorp Minerals, as described earlier, is a past producer of REEs and is currently preparing to
re-open its mine at Mountain Pass, California.
• In Nevada, about 16 miles east of the Mountain Pass mine, Elissa Resources is exploring multiple
locations called the Thor REE Project Area, where HREEs and LREEs have been discovered; at
least one of these locations is geologically similar to the Mountain Pass deposit (Elissa
Resources, 2011). To date, Elissa Resources’ exploration activities have included surface
mapping, a district-scale detailed high-resolution airborne magnetic geophysical survey,
extensive ground radiometric surveys, satellite imagery studies, petrographic studies, and
sampling programs, including channel sampling and the sampling of historical surface workings
that are remnants of a 1950s uranium-thorium prospecting rush.
• Quantum Rare Earth Developments Corporation recently has begun exploratory drilling at the Elk
Creek Project in southeastern Nebraska. The focus of these drilling efforts is to perform a
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