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 Drilling will also displace ground water entering the borehole to the ground surface, along with the drilling fluids. 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 resource assessment of niobium and associated REEs contained in a carbonatite deposit. These efforts are in the early stages, and no final determination about the resource has been made at this time (Quantum Rare Earth Developments Corporation, 2010). � Bear Lodge Rare-Earth Project is located approximately 6 miles north of Sundance, Wyoming, and is comprised of 90 unpatented federal lode claims and one state lease, for a total of about 2400 acres. It is owned by Rare Element Resources through its Wyoming-incorporated Paso Rico (USA) Company, Inc. Twenty-three of the mining claims were obtained from Phelps Dodge Corporation and are subject to 2-percent net smelter return production royalty. The site has been prospected at various times since 1949. Several areas of mineralization have been identified, including high-grade copper, molybdenum, gold, and REMs within an altered carbonatite- 3-8
Rare Earth Elements Review Section 3 – Life-Cycle Stages of Rare Earth Elements Mines alkaline-intrusive complex. Exploration efforts to date estimate that the rare earth resources at Bear Lodge could match or exceed the size and grade of deposits at Mountain Pass, California. The company web page reports that Rare Element Resources is currently exploring for rare earths and gold, and results have been very good to date. � Pea Ridge mine (formerly owned by Upland Wings / Wings Enterprises. and currently owned by Pea Ridge Resources, Inc.) is a iron mine that has been in operation for about 40 years. The site is located in Missouri. The mine, under former ownership, had planned to produce HREEs as a byproduct from the iron ore body; however, mining of an adjacent ore body containing primarily REEs had also been planned (Wings Enterprises, 2011).. A mine feasibility study is underway (Pea Ridge Resources, 2012), but no information is readily available to determine whether or not REE will be produced. The above locations are only examples of sites where some level of exploration activities have occurred, but others may exist. A general list of potential rare earth resource locations that have been documented in the United States is summarized in Appendix B, which was compiled from a combination of sources. Other deposits likely exist or are being explored that were not identified or included in Appendix B. 3.3.2.2 Mine Development The term “mine development” is applied differently, depending on the region and entities involved. It is most often understood to be primarily a planning stage; however, it is also sometimes used to denote the construction phase, considering that planning has been accomplished during the exploration stage. Feasibility Study A financial analysis and corresponding feasibility study are important parts of this stage, as defined here, and are conducted considering the market value of the metal commodity, cost of production, characteristics of the deposit, and anticipated closure costs. The results are then used to determine if the deposit should be abandoned (i.e., not likely to ever be an economically viable deposit), should remain idle (i.e., could become economically viable in the future), or if development of the deposit is economically feasible and should proceed. Typically, a feasibility study for a medium-size mine requires 3 to 4 months and, for larger projects, 6 to 9 months (De la Vergne, 2003). Concerns for the environmental effects of the proposed mining activity, and associated mine areas must be considered relative to long-term costs. The potential impacts to the immediate property, adjacent lands, and surrounding community are identified, and additional baseline environmental studies may be performed or continued during this stage. Investors may be sought using the results of the feasibility study. Mine Plan The layout and design of the mine is performed to locate stockpile areas and waste areas where these can be best managed to prevent or minimize environmental damage. Engineering design and environmental assessment should be conducted in tandem so that collected and measured data can mutually benefit both 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 3-9
Page 1 and 2: Rare Earth Elements Review Table of
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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