Proposed operations at the Bear Lodge Project will consist of the following:
- A small surface mine,
- A Physical Upgrade (PUG) Plant located adjacent to the mine for mineral pre-concentration, and
- A Hydrometallurgical (Hydromet) Plant for further concentration, impurity removal and recovery of the rare earth oxides from the mineral pre-concentrate, located in Upton, Wyoming.
Ore will be mined from an open pit. Both the Bull Hill and Whitetail Ridge ore bodies begin within a few yards, or meters, of the surface -- making them ideal for open pit mining.
Mining will utilize conventional truck and excavator open pit methods. Topsoil and overburden will be removed first to expose the mineable ore and stockpiled separately for reuse in reclamation activities. When necessary, blasting will be employed to loosen large blocks of ore. There are several ore types being mined from the two deposits, all of which will be hauled by dump truck from the mine site to separate ore stockpiles.
Mining will occur in expanding benches, with the current expected depth averaging approximately 500 feet deep. Total disturbance for the mineable pit is expected to be approximately 240 acres.
Physical Upgrade (PUG) Plant
The PUG Plant is designed to remove barren rock from the ore and thereby increase the concentration of the rare earth minerals, producing a mineral pre-concentrate. The PUG process employs a series of crushing, washing, screening, and magnetic sorting methods to concentrate the rare earth-bearing fines and reduce the associated physical mass. The closed system has been designed to be water efficient and have no effluent discharge to surface waterways. The majority of the water will be recycled at the PUG plant with the remaining being recovered upon further processing at the Hydromet Plant. Because initial mining will occur in a high-grade zone of the ore body that will not need upgrading, some construction activities at the PUG Plant will not occur until year six.
Rendering of Planned PUG Plant
The ore type and grade will vary within the mineable deposits and will be sorted accordingly. Low grade ores will be stockpiled for future processing while mid-grade and high-grade ore will be processed in the PUG Plant. It is expected that these different ores will have different mass reduction and grade characteristics. Therefore, the PUG Plant is designed to process the different ores to produce up to 500 tons per day of bulk, mixed rare earth mineral pre-concentrate. The PUG will be used to maximize the rare earth grade and recovery, while minimizing the mass of material that is transported to the Hydromet Plant each day via covered trucks.
Hydrometallurgical (Hydromet) Plant
The Hydromet Plant will be located in Upton, WY, approximately 40 miles from the mine site. Mineral concentrate will be delivered to the state-of-the-art Plant from the PUG Plant via enclosed trailered trucks.
Rendering of Proposed Hydromet Plant – Upton, WY
The Hydromet Plant will process the pre-concentrate in an acid leach circuit, followed by additional chemical processing to remove impurities and recover the rare earths. The Plant will employ proprietary technology, developed and currently being patented by Rare Element Resources. The Preliminary Feasibility Study (PFS) reflected the use of this technology and resulted in the production of a 98+% pure,total rare earth (TREO) powder.
Also, designed as a “zero discharge” facility, the Hydromet plant will recycle a majority of the hydrochloric acid (HCl) and water used in processing, eliminating discharges and helping to reduce raw material costs. The tailings from the plant will consist of the leach residue and solid residue produced from acid regeneration and will be de-watered, neutralized and disposed of at a tailings facility to be located adjacent to the Plant. The isolated Thorium will be taken to an off-site, licensed disposal facility.
Since the completion of the PFS, additional test work has demonstrated the ability to increase the purity of the TREO powder to 99.999% pure while completely removing any remaining impurities, including the majority of the cerium (Ce), the lowest valued of the rare earths. It also demonstrated the ability to separate the powder into fractions that are predominately heavy (HREE) and light (LREE) rare earth oriented.
The Hydromet Plant will incorporate a hydrochloric acid (HCl) leach to dissolve the rare earths, followed by additional chemical processing to remove impurities. Some of these impurities, such as iron, manganese, aluminum, calcium and gold, will be evaluated for post process recovery. The new technology uses two precipitation steps to remove approximately 92% of the Ce, and 100% of the remaining thorium, producing a 99.999% pure, bulk TREO powder. In a single solvent extraction step, the remaining powder can be separated into a nearly cerium-free LREE fraction containing up to 98% lanthanum, praseodymium and neodymium, and a HREE fraction that containing up to 97% of all elements from dysprosium to lutetium.
Recent bench-scale test work has confirmed the development of a process that can separate the rare earth fractions into multiple final products that will specifically meet the needs of the end user. The improvement in the purity of the product and ability to separate the different elements is expected to increase its' marketability and result in better pricing from buyers. In August 2015, the Company initiated a pilot plant testing program for this separation technology.
Schematic of Proprietary Process Technology
The Hydromet Plant will be located on private property adjacent to the Upton Regional Industrial Park. The park serves as a rail trans-loading site for the Powder River Basin.