Rare Element Resources
Bear Lodge Project
Canadian NI 43-101
Technical
Report
October 9
th
, 2014
10135-200-46 - Rev. 0
17-19
Oxalate Precipitation Chemistry
17.4.1
Precipitation Reactors
17.4.1.1
Rare Earth Oxalate Precipitation
2*RECl
3
+ 10H2O+ 3*C
2
H
2
O
2
→ RE
2
(C
2
O
2
)
3
10H2O+ 6*HCl
Reactions Extents: 90-100% depending on the element
Other ions will also precipitate as oxalates, namely thorium, and
reduce the rare earth oxalate purity. Regenerating hydrochloric acid
is also a byproduct of the oxalate reaction.
RE Oxide Kiln
17.4.1.2
Rare Earth Oxide Calcination
2*RE
2
(C
2
O
2
)
3
10H2O + 9*O
2
+ Heat (700
o
C) → 2*RE
2
O
3
+
10H2O +
12*CO
2
Reactions Extents: 100%
17.5 Process Description Unit 350 – Acid Regeneration, Metal Carbonates,
and Calcium Chloride
The Acid Regeneration Unit is designed to recover and reuse water, hydrochloric and
oxalic acid and includes precipitation of waste metal carbonates for tailings disposal.
The precipitation filtrate solution contains small but valuable amounts of hydrochloric
acid, significant residual oxalic acid together with un-precipitated metal chlorides.
Hydrochloric acid is recovered by flash vaporization of HCl and H
2
O from the filtrate
solution (350-CFL-001) followed by distillation (350-CDI-001) to obtain 18% HCl
solution and water. The water contains a minor amount of HCl (< 0.5%). Both 18%
HCl and water are reused in the process to reduce HCl cost and reduce water
consumption.
The flash column bottoms contain residual HCl, concentrated oxalic acid, and metal
chlorides. This solution is cooled and oxalic acid is crystallized (350-CRY-001) and
centrifuged (350-CFG-001). The oxalic acid crystals are recycled back to the
precipitation reactors by re-dissolution in the oxalic acid dissolution tank (500-TAK-
008). The recovery of oxalic acid reduces consumption of purchased oxalic acid by
