Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
17-2
the ore. Rare Earth Oxalates are then precipitated from the pregnant leach solution
by the addition of oxalic acid and converted to REO in a kiln. Thorium and other
impurities are removed from the REO by a nitric acid leach and double hydroxide
precipitation method. Ammonium hydroxide is used for the hydroxide precipitation
steps and produces an ammonium nitrate by product. The REE hydroxides are
converted back to REO in a final dryer.
Hydrochloric acid and oxalic acid are recovered and recirculated back into the
process for a significant reduction in the cost of these reagents. The hydromet
process also includes treatment of the base-metal loaded waste solution from the
bottom of the distillation column (or evaporator) by the addition of lime-rock and
quicklime to produce the mixed metal hydroxide solids. The filtrate from the
neutralization process contains excess calcium chloride which is a potential chemical
by-product. Leach residue is also treated with limestone & quicklime prior to shipment
to the tailings storage facility (TSF).
17.2 Process Description Unit 100 – Physical Upgrade Plant
Figures 17.1 thru 17.8 are Block Flow Diagrams which illustrate the Physical Upgrade
Plant Process Flows.
The PUG process is designed to produce a rare earth oxide pre-concentrate. PUG
pre-concentrate will be sent to the Hydromet plant for further processing.
Most of the PUG plant will not be constructed until year 9 of the project. The mine
plan employs selective methods to provide the Hydromet plant with higher grade ores
in the first nine years of operation that do not require pre-concentration. Therefore,
the construction and operation of the PUG and Hydromet plants will happen in two
phases as described in section 17.1 Process Summary.
The run of mine ore is stockpiled (100-STO-001/002) by grade and mineralization
prior to the crushing circuit. The stockpiles are individually reclaimed to feed the plant
through the dump hopper (100-HOP-001).
Size Reduction (common for all ore types)
17.2.1
Run-of-mine (ROM) ore from a stockpile (100-STO-001) is transported onto a 24”
grizzly screen (100-GRZ-001). Oversized material is sent to a stockpile (100-STO-
005) while undersized material passes under the grizzly feeder and is crushed in a
24” jaw crusher (100-JCR-001). The material is conveyed to a 3” screen (110-VIS-
