Fission Uranium’s recent prefeasibility study (PFS) for an underground-only mining scenario for the Triple R mine at its Patterson Lake South property in the Athabasca Basin region of northern Saskatchewan describes a project that would produce an average of 13.1 million lb per year (lb/y) of U3O8 over the first five years of a seven-year mine life. Capital costs to develop the project are estimated at C$1.177 billion.

With projected operating expenses of just US$7.18/lb of U3O8 produced, a pretax internal rate of return 34%, and a pre-tax NPV at 8% of C$1.33 billion, the underground PFS outlines the potential for highly economic production at Patterson Lake South, according to the company. Payback is estimated at 2.2 years.

A three-year construction period would include development of box cut and portal, access decline, ventilation shafts, underground capital development, and plant and infrastructure construction. Mining at a rate of 1,000 metric tons per day (mt/d) would be based primarily on longhole stoping in both transverse and longitudinal orientation, with isolated pockets of cut-and-fill.

Process plant design is based on conventional technology, with a flowsheet that would include grinding, leaching, liquid-solid separation via counter-current decantation, solvent extraction, yellowcake precipitation, yellowcake packaging, and tailings neutralization and thickening. An estimated 2.3 million mt of ore would be processed life-of-mine, grading 1.61% U3O8 and containing 81.4 million lb of U3O8. Process recovery is estimated at 96.8%. Life-of-mine production is planned at 78.7 million lb of U3O8.

The current underground PFS follows an earlier PFS that considered a hybrid mine approach using both open-pit and underground techniques to mine the Triple R deposit. The underground PFS highlights a substantial reduction in capital expenditure and time requirements for construction of the mine due to simplified water control measures for underground mining. The revised mining method eliminates the need for a system of dykes and slurry walls in the lake, dewatering, and overburden removal, resulting in a reduction of 90% of total mine-related earth movement. The reduced earth movement also results in reduced surface piles and an overall minimized surface footprint.