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

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Rare Earth Elements Review Section 6 – Human Health and Environmental Risks REE(s) Citation Objective/Purpose Key Findings Terbium Peng et al., 2007. Ecotoxicity of Terbium to Peroxidase Activity of Cochlearia armoracia L. Under Different Light and Temperature. J Agro- Environment Science 26: 974-976. Ytterbium Hongyan et al., 2002. Physiological Responses of Carassius auratus to Ytterbium exposure. Ecotoxicology and Environmental Safety 53: 312-316. Study the ecotoxicity effects of terbium on Cochlearia armoracia L. peroxidase (HRP) at different temperatures. Physiological and biochemical effects to the liver of Carassius auratus were investigated in vivo following 40 days of exposure to ytterbium. 6-28 The results indicate the toxic effect of Tb(III) on HRP was increased with high temperature. Glutamate-pyruvate transaminase (GPT), superoxide dismutase (SOD), catalase (CAT), glutathione Stransferase (GST), and glutathione peroxidase (GSH-Px) activities were affected in goldfish liver. CAT was most sensitive to Yb3+, indicating that CAT might be a potential tool in the biomonitoring of exposure to Yb3+ in an aquatic ecosystem.
Rare Earth Elements Review Section 7 – Summary, Key Findings, and Next Steps 7. Summary, Key Findings from Literature Review, and Potential Next Steps The purpose of this report is to serve as a technical information resource to policy makers and other stakeholders who are concerned with the potential environmental and health effects and impacts that can be identified across the REE supply chain. RTI conducted a search of the technical literature and other Internet sources related to each segment of the supply chain, including recent initiatives of U.S. government agencies that document issues associated with REE production, processing, manufacturing, end uses, recycling, and health/ecological effects. Information contained in this report also draws upon past domestic and international experience, as appropriate. The vast majority of information in this report is current. But, as noted in this report, mining and extraction of REEs is dynamic. Therefore, some details regarding who is producing what and where may have changed between the time when: (1) data collection as part of the literature search for this report was complete in July 2011, (2) the report’s contract was completed in September 2011, and (3) its subsequent publication in 2012. Although the current literature provides limited information specifically relating to REE mining, processing, recycling, and environmental or health impacts, it is expected that more information will be produced in the future as a result of the increased level of interest in REEs in the past few years. 7.1 Summary REEs include the series of 15 lanthanide metals, plus scandium and yttrium. REEs have become increasingly important in recent years because their unique chemical and physical properties have contributed to technological advances in many areas, such as wind turbines, hybrid electric vehicles, energy-efficient lighting, computers and electronics, and defense applications such as lasers. In 1984, the Molycorp Minerals, Inc. mine in Mountain Pass, CA, supplied 100 percent of U.S. demand and 33 percent of the world’s demand for rare earths. The mine was shut down in 2002 for a variety of reasons, and since that time, China has become the world’s leading producer of REEs, handling approximately 95 percent of worldwide production. Due to the increase in demand and the reduction in supply of REEs, the cost of REEs has increased dramatically in recent years. Given the strategic importance, supply concerns, and increasing cost of REEs, REE mines outside China are currently being evaluated or are in development, including multiple sites in the United States. Past producers of rare earths are re-opening idle or closed mines, and active mines that produce other metals that usually send rare earths as waste are now considering recovery of rare earth oxides. Molycorp Minerals, Inc. is at the forefront as one of the first companies to reinitiate mining operations at their existing Mountain Pass mine. Molycorp also is attempting to find better mineral processing methods that allow recovery of more rare earth oxides from the ore at a lower cost and with less environmental impact. Outside of direct mining operations, other sources of rare earths are being explored, such as recovery from recycling or urban mining. Currently, commercial recycling of rare earths is very limited; however, it is reported in the literature that, within the next year, several new commercial recycling operations will begin operation, with the focus being on magnets, batteries, lighting and luminescence, and catalysts. Mining and processing activities have the potential to create a number of environmental risks to human health and the environment. The severity of these risks is highly variable between mine and mine plant operations. The contaminants of concern will vary depending on the REE-mineral ore, the toxicity of the contaminants from the waste rock, ore stockpiles, and process waste streams. The mobility of contaminants will be controlled by the characteristics of the geologic, hydrologic, and hydrogeologic 7-1
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Rare Earth Elements Review Table of
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Foreword The U.S. Environmental Pro
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Abstract Rare earth elements (REEs)
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Table of Contents List of Acronyms
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List of Tables 2-1. Abundance of El
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Rare Earth Elements Review List of
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