Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
16-7
The mine and highway haulage trucks, for transporting the upgraded mineral
reserves to the Hydromet plant, would operate five days per week. Pit operations
would be scheduled for two 10-hour shifts per day.
Prior to delivery to the Hydromet plant, some metallurgical ore types would be simply
crushed (BH OxCa), most would require crushing and screening (BH oxide and all
WT mineral reserves), and most would also be processed through the PUG plant
(excluding high grade BH oxide and BH OxCa). Section 17 describes the overall
process flow sheet in more detail. In order to calculate the quantity of upgraded
mineral reserves delivered to the Hydromet plant, hereafter referred to as “pre-
concentrate”, WLRC developed a computer program to calculate rock mass and REO
recoveries for each metallurgical ore type on a block-by-block basis in the deposit
model. WLRC’s proprietary open pit mining simulation program was then used to
read these recoveries to compute pre-concentrate tonnages and head grades when
generating a mine production schedule.
A declining cutoff strategy was employed to maximize the present value of the mining
schedule. This strategy incorporated stockpiling lower grade material (proven and
probable reserves below the year’s cutoff grade, but above the 1.5% MTREO cutoff)
for reclamation later in the mine’s life. A starting cutoff grade was set at 3.0%
MTREO, gradually declining to the near breakeven cutoff of 1.5% MTREO by Year
16. The mining simulator reads in target ore production rates and MTREO cutoffs by
time period, and then proceeds to schedule detailed proven plus probable mineral
reserve estimates by bench, by mining phase. The program estimates advanced
stripping requirements, respecting user controls of ore exposure markers for each
phase, phase dependencies (no undercutting previous pushbacks) and sinking rates.
The resulting production schedule is reported and the user then reviews the
estimated Hydromet plant feed and makes corrections to the targeted ore tonnages
by time period. Through successive iterations, a mine production schedule can be
developed that feeds pre-concentrate at the Hydromet plant’s capacity, while meeting
advance stripping requirements for continuous ore development in the open pit.
Table 16.3 summarizes the proposed mine production schedule for the Bear Lodge
Project for the pre-production period and annually thereafter. Pre-production
stripping requirements are estimated at just over 6.9 million tons of material, including
19 ktons of high-grade stockpile and 63 ktons of low-grade stockpile. Pre-
concentrate feed rates would be 179 ktons per annum through Year 9, then 216 ktons
per annum thereafter. Open pit mining would last through the end of Year 38, after
