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

Rare Earth Elements Review Section 3 – Life-Cycle Stages of Rare Earth Elements Mines
Figure 3-1. Molycorp Minerals rare earth mine, Mountain Pass, California.
Other mine sites around the conterminous United States and Alaska have produced REE-containing
minerals in the past; however, the status of those sites is currently undetermined. A listing of known
mines that have produced REE-mineral ores or REOs and locations where REE-containing mineral
deposits have been discovered was compiled from Gupta and Krishnamurthy (2004), Orris and Grauch
(2002), and Schuler et al. (2011) and is provided in Appendix B. The only other significant REE mining
operations are located in the Sichuan, Jiangxi, Shandong, and the Inner Mongolia provinces in China
(Schuler et al., 2011); however, the Chinese REE mining operations and environmental practices are not
considered applicable for comparative purposes in this report and are not discussed in any detail. In the
absence of modern examples of mining activities for the extraction of REE ores in the United States, and
considering the variability in the mineralogy and geology of known REE reserves, the following sections
present a general discussion that introduces the life cycle of typical mining operations. The wastes
generated during each mining stage that have the potential to cause environmental effects are also
discussed, as applicable.
3.2 REE Ores
The REE metal is an elemental constituent of mineral REO ores. Concentrations of REE minerals
typically occur in igneous and metamorphic rocks and also in sedimentary placer deposits. As discussed
in Section 3.3.2.1, concentrations of the target REO in the ore have implications for selection of the
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