Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
13-34
(<0.5 wt.%). In subsequent tests, calcium was significantly reduced in the REO
product.
High precipitation rate of REEs was attributed to a recycle of oxalate crystals from the
thickener which contained 2.2% – 6.3%TREE. However, calcium content in these
crystals was high and hence lowered the purity of RE oxalate cakes in the main
circuit.
COMP E
Overall Recovery
The overall recovery of REEs from COMP E, which was ultimately transferred to a
final oxalate product, feed into a precipitation cake that included 88% Dy, 93% Eu,
94% Nd, 94% Pr, 90% Tb and 79% Y.
Counter –Current Leach
Leach efficiencies of CREEs at steady state conditions ( total acid 434 kg/t, 45
o
C)
were 89% Dy, 94% Eu, 95% Nd, 95% Pr, 91% Tb and 83% Y. Digestion of REEs was
selective over base metals. Average base metals extractions were 17% Fe, 7% Al,
63% Mg, 46% Mn and 96% Ca.
Overall hydrochloric acid dosage was 401 kg/t. However, actual consumption of fresh
hydrochloric acid was 224 kg/t due to acid recycling. Extraction of REEs increased
with time in the preleach circuit indicating that a longer residence time would be
required (> 4hours) to enhance leach efficiency.
The final leach residue composition averaged 0.57% TREE, 134 g/t Th, 42 g/t U,
7.33% Al, 10.4% Fe, 8.51% K and 23.2% Si, supporting the concept of selective
digestion of REEs over base metals and silica.
Precipitation Cascade
The precipitation campaign for Comp E was limited to a few days and therefore, two
12-hr composite samples were evaluated. Precipitation efficiency of REEs averaged
95% but, steady state precipitation efficiencies of CREEs ( Total 82 g/L oxalate
dosage) were 99% Dy, 99% Eu, 99% Nd, 98% Pr, 99% Tb and 95% Y. Thorium
precipitation was 100%.
