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Management of Radioactive Wastes from Rare Earth Element Production
D.B. Chambers*, D.G. Feasby**, L.M. Lowe***
ABSTRACT
The presence of the naturally occurring radioactive elements uranium and thorium in rare earth (RE)
resources can present challenges in achieving regulatory and social acceptance. Mineral resource
radioactivity typically generates strong public intuitive responses that may be project prohibitive.
The objectives of this paper are to demystify the presence of uranium and thorium in RE resources and to
demonstrate how a RE project can be safely developed, operated and closed from a radiological
perspective.
Radioactivity in RE resources is principally thorium-based. Thorium is interesting and challenging from a
metallurgical perspective – one of those stubborn metals commonly assessed as refractory. Thorium is
difficult to mobilise into solution and easily precipitates out. Thorium is a common element in the earth’s
crust – about 10 ppm on average, and natural geophysical systems conclusively demonstrate its immobility.
Specific mine tailings contain elevated levels of thorium, but the contained thorium is neither a significant
ecological or a personal hazard.
Waste management for a hard rock rare earth project includes the management of mineral process tailings,
waste rock, and metallurgical residue. Proven strategies are available for tailings and waste rock for all
climate conditions. The management of the metallurgical residues is potentially more challenging.
Example robust strategies for addressing these challenges are presented.
A potential way to reduce the radioactivity of rare earth metallurgical wastes is to selectively remove
uranium and thorium. Uranium oxide is readily marketable, but its concentration as a byproduct typically
triggers extensive regulatory processes. Thorium is presently not marketable, but may be so in the not-toodistant future with the development of thorium-based nuclear energy. The pro’s and con’s of uranium and
thorium byproduct recovery are summarized.
KEYWORDS
Rare earth production, thorium, radioactivity, waste management
* Arcadis Canada Inc., 121 Granton Drive, Richmond Hill ON; ** FEAS Consulting, Ottawa ON, *** Toronto, ON