Occupational Dose Evaluation in Support of the Development of
October, 2012
Rare Element Resources, Inc. Bear Lodge Project
1
SECTION 1
INTRODUCTION
Rare Element Resources, Inc. (RER) proposes to build a rare earth element (REE) mining facility
in the Bear Lodge Mountains in Crook County, Wyoming, and a processing facility near Upton,
in Weston County, Wyoming. The proposed mining facility consists of an open pit mine called
the Bull Hill Mine (BHM) and a physical upgrade plant (PUG). The proposed processing facility
will consist of a hydrometallurgical plant (Hydromet) and tailings storage facility (TSF). In this
report, the mining and processing facilities are collectively referred to as the Bear Lodge Project
(BLP).
1.1
Project Overview
The BHM site is located in central Crook County, northeastern Wyoming (see Figure 1.1), in the
north-western portion of the Black Hills uplift. The property is situated in the central Bear Lodge
Mountains. The BLP lies about 7 air miles (11 kilometers [km]) or 12 road miles (19 km)
northwest of the town of Sundance, Wyoming. The BHM will be a conventional truck and
shovel open pit operation that will extract near-surface ore containing rare earth oxides (REO).
Ore from the BHM will be hauled to the nearby PUG where a rare earth minerals pre-concentrate
will be produced using a screening and washing process. The pre-concentrate then will be
transported by truck to the Hydromet facility in Upton, Wyoming.
In addition to REO, the BLP ore contains naturally occurring radioactive material (NORM)
consisting of thorium, uranium, and their associated radioactive decay products. NORM is
ubiquitous and present in rocks and soils in varying concentrations, with United States
background concentrations typically on the order of 1 to 10 parts per million (ppm)
(UNSCEAR, 2000). Uranium and thorium concentrations in the BLP ore average
approximately 109 and 377 ppm, respectively: above typical background levels.
The Hydromet is located in north-central Weston County, in northeastern Wyoming. The
property is located 3 road miles (5 km) northwest of Upton, Wyoming and approximately 30
road miles (64 km) southwest of Sundance, Wyoming. The Hydromet is designed to have two
parallel circuits to process the mineral pre-concentrate from the PUG. The hydrometallurgical
process uses a 20 percent hydrochloric acid solution, heated to 194 degrees Fahrenheit (90
degrees Celsius) to leach the REEs from the pre-concentrate. Iron then is precipitated from the
solution, and calcium and manganese are extracted by an ion exchange process.
Finally
,
REEs
are precipitated as carbonates through neutralization with sodium carbonate as a product. The
final product will be shipped via truck or rail to other facilities for further processing.
