The Thor lake deposit is a world class resource of rare earth (REE) metals and minerals in Canada. Development
work to optimize a REE mineral recovery process flow sheet is underway, however, given the ore
mineralogy ; the developed reagent scheme is relatively complex. As part of a research project, micro-flotation
tests were conducted on a feed sample in order to examine fa ctors affecting stream partitioning.
SEM–EDX was performed to eval uate variability in grain composition between streams (concentrate
and tails) and TOF-SIMS surface analysis was used to determine statistically significant differenc es in surface
species particularly related to potential activation (or depression) of the examine d mineral phases.
SEM–EDX analysis reveal that the concentrate has a significantly higher proportion of REE bearing grains
(carbonates and phosphates) relative to the tail (almost none were identified). Spectral fingerprinting by
TOF-SIMS has allowed for the identification of all reagent species investigated. Reagent signal intensity
discriminatio n on test stream mineral surfaces was observed by the TOF-SIMS analysis using reagents
at plant concentration levels. TOF-SIMS analysis confirmed that REE bearing grains reporting to the concentrate
are doing so in response to collector attachment whereas grains reporting to the tail are doing so
in response to a lack of collector and/or in combination with the presence of the dep ressant. The surface
analysis of gangue phases reveal a similar reagent discrimination; the signal intensity of collector species
was significantly higher on the concentrate samples relative to the tails while depressant species were
significantly enriched on the surface of the gangue phases in the tail samples. A detailed eval uation of
the surface species representing the various reagents used in flotation scheme revealed a distinct competitive
relationship between two of the reagents. The surface analysis identified that when used in concurrently,
there appears to be a negative feedback resulting in a significant reduction in loading for
several of the collectors on grains reportin g to the concentrate . An evaluation of the effect of reagents
on REE mineral in pilot plant is currently under way