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

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Rare Earth Elements Review Section 3 – Life-Cycle Stages of Rare Earth Elements Mines purposes and allow for collaboration of engineers and environmental scientists; however, while this is best practice, the approach is sometimes not used due to inadequate planning or logistical difficulties. Mitigation measures can then be addressed more efficiently through management plans and compensation measures that are integrated into the feasibility models to evaluate costs. REEs commonly occur in ores that also contain uranium and thorium. Ores containing the REE-bearing mineral monazite are particularly high in concentrations of thorium (Long et al., 2010). Uranium also occurs in or with ore deposits that contain REE-bearing minerals. The amounts of radioactive elements in the ore is not dependent upon the mineral type specifically, but more on the petrogenesis of the deposit containing the ore. In general, nearly all rocks, soils, and water contain small amounts of radioactive materials, such as uranium, thorium, radium, radioisotopes of potassium, lead, polonium, and their decay products. When naturally occurring radioactive materials (NORM), in their undisturbed natural state, become purposefully or inadvertently concentrated, either in waste by-products or in a product, they become technologically enhanced naturally occurring radioactive materials (TENORM) (U.S. EPA, 1999). Waste areas containing high concentrations of uranium and thorium require complex management. Management begins at the mine design stage, where the mining methods and milling plant processes are planned to optimize a waste reduction-minimization strategy. The treatment of tailings is a significant safety concern, as well as an environmental issue. The EPA reports (U.S. EPA, 1999) that the radiation levels from waste rock and sludges associated with the production of REOs range from 5.7 to 3,224 pCi/g. Additional treatment circuits are generally required to precipitate radium from tailings, and additional controls are needed to manage radon. Production and management of radioactive mining and milling wastes is tightly controlled by national (including the Safe Drinking Water Act, Clean Water Act, Comprehensive Environmental Response, Compensation and Liability Act [CERCLA], and Clean Air Act) and state regulations, and if REE is produced with commercial uranium or thorium, then international protocols and agreements also may apply. Information pertaining to laws and regulations that apply to TENORM can be found at EPA’s Radiation Protection website (http://www.epa.gov/radiation/tenorm/regs.html). The challenge is generally balancing the human health and environmental risks with production costs. The issues associated with these materials can affect the feasibility and viability of a proposed mining project, especially when addressing plans to reopen older mining sites. Tighter regulation on the use of radioactive minerals has been identified as the primary factor that pressured many sources of monazite out of the REEs market during the 1980s (Long et al., 2010). Processing these ores containing radionuclides subsequently increases the concentration of naturally occurring radioactive materials, and the levels of radioactivity can become higher than background levels near waste management areas. However, it should be noted that radioactive wastes from mining and milling operations are not the same as waste containing special nuclear materials that are associated with the production of enriched (i.e., increased concentrations of highly radioactive isotopes) radioactive materials generated by nuclear fuel cycle facilities or disposed of by nuclear power plants. The principal issue at mining and milling sites is the volume of wastes containing natural radioactive elements that are produced and managed. Environmental Studies This section is presented for general background and to provide some perspective of the complexity of mine siting studies under NEPA; however, the information presented here should not be considered as guidance, nor should it be taken as a comprehensive discussion of the types of environmental assessment activities that may be required. 3-10
Rare Earth Elements Review Section 3 – Life-Cycle Stages of Rare Earth Elements Mines In general, if mines are located on or adjacent to federally managed lands or will have discharges to surface water then an Environmental Information Document (EID), also known as an Environmental Study or Environmental Report under some programs, is required under NEPA. Preparation of this report is generally performed by the proponent during early mine stage activities as the viability of the mining operations is being assessed. The EID describes the project, characterizes the environment that potentially may be impacted by the mining activities (including cumulative impacts), assesses the potential severity of any impact, identifies mitigation measures to avoid or lessen the impacts, and discusses alternatives for methods and operations, that may include an evaluation of the critical need of the commodity (e.g., availability of the commodity from other markets, substitute materials, or recycling). Information from the proponent’s EID is used by the managing agency for the project to prepare an Environmental Assessment (EA) report describing the potential for environmental impact and the preferred alternative. If the mine project is considered a major federal action that has the potential to significantly affect the quality of the human environment, then the EID and/or EA is used by the lead government agency to develop an Environmental Impact Statement (EIS); however, additional environmental baseline and engineering studies may be needed. The EIS is then reviewed by EPA and other agencies, if applicable, as part of the NEPA process to determine if unavoidable adverse impacts will occur, and if irreversible and irretrievable commitments of resources are likely, considering connected actions, cumulative actions, and similar actions. A period of public review and the issuance of a Record of Decision (ROD) follows. If an EIS is implemented, monitoring is required for any mitigation steps required and implemented. Common baseline studies performed to support the EID might include an evaluation of aquatic resources (including wetlands), terrestrial habitat, ground water quality and supply, air quality, and human population and demographics. Each of these studies focus on characterizing the environment that potentially may be affected by the operations and activities at the site. The information from baseline studies is then used in the EID to assess the potential impact that the operations and activities may have on the site and surrounding environment, relative to the potential impacts identified and anticipated for the mining method used and the associated operations and processes. Impact may include degradation of habitat or habitat alteration or loss; however, in some special cases, habitat may actually be enhanced or created. Water use for mining operations may also cause flow alterations that have adverse impacts to aquatic habitat, or in-stream structures used for water control may obstruct fish movement, migration, and spawning patterns. An aquatic resource study generally evaluates the distribution, abundance, and condition of fish species, benthic macroinvertebrates, and amphibians, along with the distribution and extent of the habitat and riparian zones. To assess existing stress on the aquatic environment, water quality criteria are evaluated against the actual condition of the water body, and toxicity studies and metric analysis of macroinvertebrates may also be performed. Aquatic impacts from mining and mine processors are often considered to be the most significant. Milling and processing operations are sometimes shared by multiple mines, and ore must be conveyed to the mill or processor site. The impacts to health and safety from the method used for ore conveyance, often by heavy truck or railway, through in-route communities and sensitive areas must be considered in relation to existing traffic patterns, spillage of loads along routes, and the degradation of air quality. This generally includes the release of windblown air particulates and vehicle exhausts. However, in addition to air particulates, other studies may be necessary to evaluate the potential impacts from stationary and mobile sources of air emissions that could emit any of the hazardous air pollutants (HAPs) that are regulated under the Clean Air Act. In order to determine the severity of potential impacts to nearby human receptors, a population study is usually performed. Land-use mapping is also a common analysis performed to aid with population studies and to help identify farming areas, parks, schools, hospitals, and other potentially sensitive areas (both human and ecological habitat) adjacent to the proposed mine site. Evaluation of local demographics is generally performed to insure fair treatment of racial, ethnic, and socioeconomic groups. 3-11
Page 1 and 2: EPA 600/R-12/572 | December 2012 |
Page 3 and 4: Foreword The U.S. Environmental Pro
Page 5 and 6: Abstract Rare earth elements (REEs)
Page 7 and 8: Table of Contents List of Acronyms
Page 9 and 10: List of Tables 2-1. Abundance of El
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