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

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6. Potential Human Health and Ecological Risks of Production, Processing, and Recycling of REEs.................................................................................................................................................... 6-1 6.1 Generalized Conceptual Site Model for Environmental Risk from a REE Mine and Mineral Processing Plant.......................................................................................................... 6-2 6.1.1 Contaminant Release and Transport ..........................................................................6-6 6.1.2 EPA Studies of Hardrock Mine Environmental Risks ............................................6-10 6.2 Pathway and Exposure Scenarios for REE-Recycling ...........................................................6-14 6.3 Documented Human Health and Ecological Effects from Exposure to REE .........................6-15 7. Summary, Key Findings from Literature Review, and Potential Next Steps ......................................7-1 7.1 Summary ................................................................................................................................... 7-1 7.2 Key Findings ............................................................................................................................ 7-2 7.3 Suggested Next Steps ............................................................................................................... 7-3 8. References ........................................................................................................................................... 8-1 Appendices A Selected Chemical Properties of REEs B Locations of REE-Producing Mines and REE-Containing Mineral Deposits in the U.S. C Process Flow Diagrams for Extraction and Processing Operations List of Figures 2-1. Periodic table of the elements showing the division between LREES and HREES (Schuler et al., 2011)..................................................................................................................... 2-3 2-2. Map showing occurrences of REEs, by rock type (adapted from multiple sources, see Appendix B). .................................................................................................................................. 2-5 2-3. In-use stocks of selected REEs by specific application or industry (in gigagrams) (Du and Graedel, 2011). ............................................................................................................................. 2-7 2-4. Global production of rare earth oxides (Du and Graedel, 2011)................................................... 2-8 3-1. Molycorp Minerals rare earth mine, Mountain Pass, California. ..................................................3-3 3-2. Typical time frame for a mine project. ....................................................................................... 3-12 3-3. Aerial image of Pea Ridge magnetite mine, Missouri. ...............................................................3-16 3-4. Conventional hardrock deposit mining process and wastes emissions. ......................................3-22 3-5. Conventional placer deposit processing and wastes emissions. ..................................................3-22 4-1. Conventional placer deposit resource processing and potential wastes emissions. ......................4-2 4-2. Conventional hardrock resource processing and potential wastes emissions. ..............................4-3 4-3. Anticipated Molycorp Mountain Pass mine water reclamation process and potential waste emissions. .......................................................................................................................... 4-10 5-1. Representative rare earth oxide prices from 2007–2010 (The 2007–2010 figures are fourth-quarter [Q4] average prices. The 2011 numbers represent spot prices on February 25).................................................................................................................................. 5-2 5-1. REE recycling steps and waste emissions. .................................................................................... 5-4 5-2. Left: Dismantling table with pneumatic tools used for manual dismantling of hard disks. Right: Components resulting from the process and including REE-containing magnets (upper right corner) (Schluep et al., 2009). ................................................................................... 5-6 6-1. Generic above-ground hardrock mine conceptual site model and exposure pathways (U.S. EPA, 2009a).................................................................................................................................. 6-5 6-2. Sources of potential human exposures resulting from mining operations (U.S. EPA ORCR, 2010). ............................................................................................................................. 6-11 6-3. Sources of potential exposures of current and future ecological receptors resulting from mining operations (U.S. EPA OCRC, 2010). .............................................................................6-12 6-4. “Low–tech” gold recycling in Bangalore/India (Schluep et al., 2009)....................................... 6-14 viii
List of Tables 2-1. Abundance of Elements in the Earth’s Crust (Wedepohl, 1995)..................................................2-2 2-2. Rare Earth Elements, Their Applications, and Potential Supply Issues for Clean-Energy Technologies................................................................................................................................. 2-6 2-3. Distribution of REEs by End Use in 2008 (U.S. DOI/USGS, 2010) ............................................2-7 2-4. Current Activities at Selected, Potential U.S. REE Mines ............................................................2-9 3-1. Numbers of Existing Mines by State Where Potential REE Resources Have Been Reported (see Appendix B for References) ................................................................................3-18 4-1. Rare earth extraction methods (adapted from Meyer and Bras, 2011) .........................................4-6 4-2. Rare Earth Processing Waste Streams and Their Hazardous Waste Potential (U.S. EPA, 1991) ............................................................................................................................................. 4-8 5-1. Recycling Operations, Technologies Utilized, Current Status, and Benefits................................5-8 6-1. Summary of pollutants, impacted environmental media, emission sources, and activity associated with REE mining, processing, and recycling...............................................................6-2 6-2. Frequency of Various Types of Impacts from CERCLA Sites (U.S. EPA, 1995)......................6-13 6-3. REEs and Available RfCs and RfDs ........................................................................................... 6-17 6-4. Selected Toxicity and Epidemiology Findings for Rare Earth Elements, ..................................6-17 6-5. Selected Biomonitoring Findings for Rare Earth Elements ........................................................6-22 6-6. Selected Ecotoxicity Findings for Rare Earth Elements .............................................................6-25 ix
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: Table of Contents List of Acronyms
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Rare Earth Elements Review Section
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Rare Earth Elements Review Appendix
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