Ausenco was lead consultant in a revised Pre-Feasibility Study (PFS) to develop Seabridge Gold’s Courageous Lake gold mine in Canada’s Northwest Territories. Design optimization included reduced infrastructure and process plant footprint along with other enhancements to tailings management and processing. The revised PFS improved the project economics such as NPV and reduced the initial capital cost.
The Challenge
Seabridge Gold’s Courageous Lake project is a greenfield open pit mine and processing plant located on the shore of Matthews Lake, 240 km northeast of Yellowknife, Northwest Territories. Situated in the heart of the Courageous Lake Greenstone Belt (CLGB), the site is one of Canada’s largest undeveloped gold projects, with more than 11 million ounces of gold measured and indicated and the host for former past producing mines; the Tundra and Salmita mines. Seabridge approached Ausenco to revise the 2012 PFS by leveraging our deep expertise in delivering capital efficient projects that would improve the profitability of the mine.
The Better Way
Ausenco assessed the original layout of the infrastructure and process plant and optimized it to achieve a more compact footprint, thus reducing the bulk materials, steel and concrete, required to build the project, thereby lowering the upfront capital costs
Due to the high ratio of waste rock to tailings, tailings management at the site was improved by switching to a co-placement waste management facility, reducing its overall footprint. The waste management facility considered a paddock system using a thick waste rock platform as a drainage layer and wide waste rock berms to contain and drain the tailings. Within the platform a series of seepage collection underdrains will be utilized to capture free water and transport water to collection ponds for re-use in the process plant and mine. The use of the waste rock as a drainage system decreased consolidation time, improved in-situ density, degree of saturation and the stability of the tailings. Once the tailings are fully drained, the next lift paddock system will be constructed. A stockpile of waste rock stored on the exterior of the facility will be used to cover the final exposed lift of tailings with waste rock. This approach reduced the cost and potentially the environmental risk of the project.
Finally, through a series of trade-off studies it was determined that Pressure Oxidation & Leaching (POX) was the most cost-effective and efficient processing solution for the ore type. By producing doré gold that will be air transported from site, the expense and risk of trucking concentrate over the seasonal ice road was mitigated.
The Outcome
Ausenco’s 2024 PFS presents a considerably more profitable mining operation than the 2012 PFS, achieving a reduction in initial capital and operating costs, and overall ground disturbance. The study demonstrates production of 2.5 million ounces of gold over a reduced initial 12.6 year life of mine. These improvements have resulted in a 73% increase in after tax NPV and a 50% reduction in initial capital.