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

Rare Earth Elements Review Section 6 – Human Health and Environmental Risks
From a previous study (U.S. EPA, 1995) of risks to human health and the environment from hardrock
mines, it was concluded that the 66 hardrock mining cases illustrated that significant human health and
environmental damages were caused by the management of wastes from mining and mineral processing,
particularly placement in land-based units. Molycorp Minerals rare earth mine in Mountain Pass, CA, was
one of the sites included in the study. Wastes subject to the RCRA Bevill Amendment were found to be
the cause of the damages. These damages occurred in all hardrock mining sectors and across all
geographic regions of the United States. Table 6-2 excerpted from the report summarizes the type of
impacts.
Table 6-2. Frequency of Various Types of Impacts from CERCLA Sites (U.S. EPA, 1995)
Type of Impacts
Portion of Damage Cases
(Total NPL Sites = 66)
Surface water contamination 70 percent of cases
Ground water contamination 65 percent
Soil contamination 50 percent
Human health impacts 35 percent
Flora and fauna damage 25 percent
Air dispersion or fugitive emissions 20 percent
6.1.2.2 Acid Mine Drainage at CERCLA Sites
In another review by EPA of 156 hardrock mine sites, the results showed that approximately 30 percent
(or about 45) of the sites had problems with acid mine drainage (U.S. EPA, 2004). The report also
suggested that acid mine drainage occurred most often in EPA Regions 8, 9, and 10. The EPA OIG
(2004) also reiterated the concern from the National Wildlife Federation that sites where AMD is present
should be carefully monitored as “the presence of acid mine drainage is either underestimated or ignored
until it becomes evident, at which time the costs often exceed the operator’s financial resources, leading
to bankruptcy or abandonment of the site in many cases.” As previously stated, it is not anticipated that
the mining of REE will typically produce AMD given the typical geochemistry of these deposits.
6.1.2.3 Prospective REE Mining Sites and CERCLA Review
A comparison of USGS (Orris et al., 2002) data and EPA CERCLA documents revealed four mines that
have been damage case sites. While these sites are not yet being mined for REEs, they have been
identified as potential future sources:
� Maybe Canyon Phosphate Mine (Superfund site);
� Mountain Pass REE Mine (when owned by Molycorp; not to be confused with current owner,
Molycorp Minerals, LLC);
� Smoky Canyon Phosphate Mine (Superfund site); and
� Bokan Mountain Uranium Mine (not on NPL but Federal Facilities review site).
Releases of radionuclides were the environmental impacts that were investigated for both Mountain Pass
and Bokan Mountain mines. Maybe Canyon Mine was in operation between 1977 and 1984.
Approximately 120 acres of waste rock (29 million cubic yards) was present from which selenium and
other hazardous substances were reported to have contaminated ground water and surface water (U.S.
Department of Agriculture, 2011). Selenium contamination is a common problem at phosphate mines and
it was also found to be an environmental contaminant of concern at the Smoky Canyon Mine.
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