NI43-101Pre-Feasibility Study Report - page 217

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
For Comp B, oxalic acid consumption averaged 76.2 g/L (grams of oxalic acid per liter
of feed solution to the precipitation circuit) equivalent to 239 kg/t concentrate solids
without any oxalate recycling. Significant amount of non-precipitated REEs were
crystallized in the barren PLS thickener (post precipitation circuit) but were not
recycled. The solid oxalate crystals that settle out to the bottom of the thickener at
room temperature, contain between 4.7% - 48.1% rare earth oxalates and can be
recovered to reduce losses. Therefore, overall recoveries of REEs were slightly low
due to non-recycled rare earth oxalates during this test campaign.
Overall Recovery
The overall recoveries of CREEs from the COMP C composite included: 84% Dy,
90% Eu, 90% Nd, 89% Pr, 86% Tb and 80% Y.
Counter –Current Leach
Leach efficiencies during steady state conditions (317 kg/t at 45°C) were 81% Dy,
89% Eu, 86% Nd, 86% Pr, 84% Tb and 77% Y with iron extraction averaging 18%.
HCl acid addition to the leach plant was 308 kg/t; however, actual consumption of
fresh hydrochloric acid was 217 kg/t due to acid recycling.
REE extraction increased with residence time implying that a longer retention is
required in the preleach section (>4hours) for Comp C. In the leach section, a
residence time of 1.37 hours was sufficient to achieve higher REE extractions.
Average composition of the leach residue was 0.80% TREE, 242 g/t Th, 55 g/t U,
6.86% Al, 8.72% Fe, 8.27% K and 24.0% Si.
Precipitation Cascade
Precipitation of REEs with oxalic acid averaged 95% throughout the test campaign.
Critical rare earths were 100% precipitated at steady state conditions (72 gpL, oxalate
dosage) except for Tb (99%) and thorium was completely sequestered from the PLS.
In this test campaign, significant amounts of calcium were co-precipitated with REEs
due to low acidity (< 22 gpL) in the feed solution to the oxalate precipitation circuit.
The RE oxalate product contained 18.1 wt.%Ca, 0.071%Th and other metal traces
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