Rare Earth Elements: A Review of Production, Processing ...
Rare Earth Elements: A Review of Production, Processing ...
Rare Earth Elements: A Review of Production, Processing ...
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6. Potential Human Health and Ecological Risks <strong>of</strong> <strong>Production</strong>, <strong>Processing</strong>, and Recycling <strong>of</strong><br />
REEs.................................................................................................................................................... 6-1<br />
6.1 Generalized Conceptual Site Model for Environmental Risk from a REE Mine and<br />
Mineral <strong>Processing</strong> Plant.......................................................................................................... 6-2<br />
6.1.1 Contaminant Release and Transport ..........................................................................6-6<br />
6.1.2 EPA Studies <strong>of</strong> Hardrock Mine Environmental Risks ............................................6-10<br />
6.2 Pathway and Exposure Scenarios for REE-Recycling ...........................................................6-14<br />
6.3 Documented Human Health and Ecological Effects from Exposure to REE .........................6-15<br />
7. Summary, Key Findings from Literature <strong>Review</strong>, and Potential Next Steps ......................................7-1<br />
7.1 Summary ................................................................................................................................... 7-1<br />
7.2 Key Findings ............................................................................................................................ 7-2<br />
7.3 Suggested Next Steps ............................................................................................................... 7-3<br />
8. References ........................................................................................................................................... 8-1<br />
Appendices<br />
A Selected Chemical Properties <strong>of</strong> REEs<br />
B Locations <strong>of</strong> REE-Producing Mines and REE-Containing Mineral Deposits in the U.S.<br />
C Process Flow Diagrams for Extraction and <strong>Processing</strong> Operations<br />
List <strong>of</strong> Figures<br />
2-1. Periodic table <strong>of</strong> the elements showing the division between LREES and HREES<br />
(Schuler et al., 2011)..................................................................................................................... 2-3<br />
2-2. Map showing occurrences <strong>of</strong> REEs, by rock type (adapted from multiple sources, see<br />
Appendix B). .................................................................................................................................. 2-5<br />
2-3. In-use stocks <strong>of</strong> selected REEs by specific application or industry (in gigagrams) (Du and<br />
Graedel, 2011). ............................................................................................................................. 2-7<br />
2-4. Global production <strong>of</strong> rare earth oxides (Du and Graedel, 2011)................................................... 2-8<br />
3-1. Molycorp Minerals rare earth mine, Mountain Pass, California. ..................................................3-3<br />
3-2. Typical time frame for a mine project. ....................................................................................... 3-12<br />
3-3. Aerial image <strong>of</strong> Pea Ridge magnetite mine, Missouri. ...............................................................3-16<br />
3-4. Conventional hardrock deposit mining process and wastes emissions. ......................................3-22<br />
3-5. Conventional placer deposit processing and wastes emissions. ..................................................3-22<br />
4-1. Conventional placer deposit resource processing and potential wastes emissions. ......................4-2<br />
4-2. Conventional hardrock resource processing and potential wastes emissions. ..............................4-3<br />
4-3. Anticipated Molycorp Mountain Pass mine water reclamation process and potential<br />
waste emissions. .......................................................................................................................... 4-10<br />
5-1. Representative rare earth oxide prices from 2007–2010 (The 2007–2010 figures are<br />
fourth-quarter [Q4] average prices. The 2011 numbers represent spot prices on<br />
February 25).................................................................................................................................. 5-2<br />
5-1. REE recycling steps and waste emissions. .................................................................................... 5-4<br />
5-2. Left: Dismantling table with pneumatic tools used for manual dismantling <strong>of</strong> hard disks.<br />
Right: Components resulting from the process and including REE-containing magnets<br />
(upper right corner) (Schluep et al., 2009). ................................................................................... 5-6<br />
6-1. Generic above-ground hardrock mine conceptual site model and exposure pathways (U.S.<br />
EPA, 2009a).................................................................................................................................. 6-5<br />
6-2. Sources <strong>of</strong> potential human exposures resulting from mining operations (U.S. EPA<br />
ORCR, 2010). ............................................................................................................................. 6-11<br />
6-3. Sources <strong>of</strong> potential exposures <strong>of</strong> current and future ecological receptors resulting from<br />
mining operations (U.S. EPA OCRC, 2010). .............................................................................6-12<br />
6-4. “Low–tech” gold recycling in Bangalore/India (Schluep et al., 2009)....................................... 6-14<br />
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