NI43-101Pre-Feasibility Study Report - page 483

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
operating life of 45 years. The total tonnage of waste generated over the 45-year
project life is estimated to be about 15.8 million tons, including neutralization
amendments. Initial Geochemical Characteristics
The Hydromet plant leach tailings and precipitate residue streams have associated
paste pH values around 1 and 0, respectively, and are thus acidic. Geochemical
analysis by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) methods
indicates that both waste streams have metals concentrations. Furthermore, the
residue appears as a soluble crystalline salt and likely to release most of its metal
fraction upon contact with water (including barium, chromium, iron, lead, manganese,
molybdenum, strontium, uranium, vanadium, and zinc).
However, the leach tailings contain a significant oxide (primarily iron oxide) and lesser
carbonate component; both phases will solubilize over time if exposed to acidic
solutions, and further metals release can be expected.
These tails will therefore be amendmended with alkali material which provides the
following benefits:
The amendment neutralizes waste acidity;
The amended material may be less soluble;
The tails will be dewatered and admixed with limestone and quick lime to achieve
a neutral pH. The high iron (in the form of iron oxides) content of both waste
streams is not likely to solubilize at neutral pH and will provide significant
attenuation of most metals via surface complexation. TSF Design
A) Description and Capacity
The planned TSF is located west of the proposed Hydromet plant and was sited to
account for current property boundaries and adopted offsets from utility easements
and public roads. In addition, Golder established the TSF limits east of the surface
water drainage divide that runs along the west side of the TSF site and west of the
gas line utility easement through the eastern side of Rare Element’s property. The
design of the planned TSF has been developed to accept the waste product from the
Hydromet plant assuming a filtered (dewatered) and neutralized material suitable for
truck transport to the TSF and placed as a dry-stacked material using small dozers to
grade and maintain surfaces of the stacked tailings. The material will be graded to
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