Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
13-1
13 Mineral Processing and Metallurgical Testing
13.1 Historical Test-work
Metallurgical test work was conducted by four laboratories on various components of
the project in order to provide the necessary design criteria for this pre-feasibility
study. The initial bench scale testwork was conducted by Mountain States R&D
International (MSRDI). Subsequently, a pilot scale test program conducted and
completed in early 2012 by Hazen Research Laboratories. A parallel series of tests to
verify the Hazen process work was conducted by Nagrom of Perth, Australia.
The test work mentioned above tested the use of conventional technology and
formed the basis for the NI 43-101 compliant PFS report: Roche Engineering Inc.,
“Rare Element Resources Inc., Bear Lodge Project, Canadian NI 43-101”, April 13,
2012. The results of this early testing are not relevant to the current processing
methods.
13.2 Rare-Earth Metallurgical Testing
SGS Minerals Services has conducted the most recent bench-scale and pilot-scale
testing programs for the PUG plant and the most recent bench-scale and pilot plant
testing programs for the Hydromet plant.
This progression in testing is viewed as an important series of steps in determining
the amenability to extraction of rare earths from the Bear Lodge ore. Samples were
collected from a combination of PQ and HQ core holes and bulk sampling as
described in Chapter 11. The tested samples were representative of typical Bull Hill
oxide and oxide carbonatite mineralization, which represent the majority of the
resource. Whitetail ore was also included in the test program which had not been
previously tested. Partially oxidized and stockwork mineralization were not tested in
this program since this material will not be part of the proposed mining plan.
Variability testing was completed to evaluate how ore types in all areas of the pit
respond to screening, gravity separation and magnetic separation. It was found that
in order to optimize recoveries from all ore types, three different physical upgrade
flowsheets would be required.
Ultimately, it has been found that the most recent test work by SGS Lakefield, which
uses crushing and screening in combination with various configurations of gravity and
magnetic separation, (depending on ore type) provides the optimum grade and
recovery of pre-concentrate to the hydromet plant. Further, the precipitation of PLS
using oxalic acid, in combination with numerous other process improvements,
