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

Rare Earth Elements Review Section 5 – Rare Earth Element Recovery/Alternative Material Use
5.4 Environmental Implications of Recycling REEs
As recently reported by UNEP (Schluep et al., 2009), uncontrolled recycling of e-wastes has the potential
to generate significant hazardous emissions. While this report is focused on e-wastes, the emission
categories presented below pertain to the recycling of other types of wastes as well:
1. Primary emissions – Hazardous substances contained in e-waste (e.g., lead, mercury, arsenic,
polychlorinated biphenyls [PCBs], ozone-depleting substances).
2. Secondary emissions – Hazardous reaction products that result from improper treatment (e.g.,
dioxins or furans formed by incineration/inappropriate smelting of plastics with halogenated
flame retardants).
3. Tertiary emissions – Hazardous substances or reagents that are used during recycling (e.g.,
cyanide or other leaching agents) and are released because of inappropriate handling and
treatment. Again, as reported by UNEP (Schluep et al., 2009), this is the biggest challenge in
developing countries engaged in small-scale and uncontrolled recycling operations.
For recycling operations using pyrometallurgy, facilities need to have regulated gas treatment
technologies installed and properly operating to control VOCs, dioxins, and other emissions that can form
during processing.
In hydrometallurgical plants, special treatment requirements are necessary for the liquid and solid effluent
streams to ensure environmentally sound operations and to prevent tertiary emissions of hazardous
substances.
Recovering metals from state-of-the art recycling processes is reported as being 2 to 10 times more
energy efficient than smelting metals from ores. Recycling also generates only a fraction of the CO2
emissions and has significant benefits compared to mining in terms of land use and hazardous emissions.
While examples are not provided in the literature specifically for REEs, production of 1 kg aluminum by
recycling uses only one-tenth or less of the energy required for primary production and prevents the
creation of 1.3 kg of bauxite residue, 2 kg of CO2 emissions, and 0.011 kg of SO2 emissions. For precious
metals, the specific emissions saved by state-of-the-art recycling are reported as being even higher
(Schluep et al., 2009).
Schuler et al. (2011) report that when compared with primary processing, recycling of REEs will provide
significant benefits with respect to air emissions, groundwater protection, acidification, eutrophication,
and climate protection. This report also states that the recycling of REEs will not involve radioactive
impurities, as is the case with primary production.
Additional benefits of recycling that are not directly linked with the environment include improved supply
of REEs, and therefore less dependence on foreign sources; the potential for reduction in REE costs due
to supply increases and reduction of the current “monopoly” from foreign suppliers; and the potential for
job creation from an expanded recycling industry.
5.5 Research on Alternatives to REEs
Research into alternative materials is another strategy that is being explored in response to the REE
supply issues. Generally, this can fall into two main categories: research into alternatives to REEs, or
research into alternative product designs that require fewer or no REEs. Schuler et al. (2011) provides an
analysis and summary of the substitutes. This reference, along with many others, stresses the need for
additional research in this area. As reported in March 2010 by Science magazine (Service, 2010),
examples of selected research efforts under way include the following:
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