Rare Element Resources
Bear Lodge Project
Canadian NI 43-101
Technical
Report
October 9
th
, 2014
10135-200-46 - Rev. 0
17-23
Oxalic Acid Storage
Anhydrous Oxalic acid will be shipped to the plant in super sacs and stored. The
super sacs will be transferred into Silo (500-SIL-004) and continuously fed to
oxalic acid Dissolution Tank (500-TAK-08). Crystallized oxalic acid from
centrifuge (350-CFG-001) and oxalic acid slurry from thickener (300-THK-002) are
also fed to the Dissolution Tank and re-dissolved. The oxalic acid solution is then
fed to the precipitation process.
Ammonia and Ammonium Hydroxide Storage
Anhydrous ammonia will be delivered and stored in tank (500-TAK-011). 20%
ammonium hydroxide solution is produced by feeding anhydrous ammonia and
condensate water to absorption column (500-CAB-001). Recycled ammonium
nitrate solution may also be used to produce ammonium hydroxide solution.
Ammonium Hydroxide Chemistry
17.7.1
Ammonium hydroxide absorption column
Ammonium hydroxide reaction
NH
3
+ H2O → NH4(OH)
Reaction Extent: 100%
17.8 Process Description Unit 600 – High Purity REO Product
Nitric Acid Leach
17.8.1
The REE oxide from calcination (300-KLN-001) is re-dissolved in nitric acid. The
REE oxide is first slurried with condensate water or ammonium nitrate solution in
agitated tank (600-TAK-001). From tank (600-TAK-001) the slurry overflows to the
first nitrate reactor (600-REA-010) where 65% nitric acid is added. The nitrate
reaction takes place in three reactor tanks (600-REA-010, 011, 012) operated in
series. The slurry flows through the nitrate reactors by overflow. Any one of the three
reactor tanks may be taken out of service and bypassed for maintenance. The
remaining two reactor tanks are sized to provide the required residence time of 4
hours. The REE oxide slurry is almost completely re-dissolved by nitric acid. The
nitrate leach reactor output is filtered to remove the solid residue in filter press (600-
PFT-003).
