Ausenco integrated services from across our global network to advance an existing PFS to a full Feasibility Study at the Eskay Creek gold and silver mine project in British Columbia’s golden triangle. With much of the FS data representing a significant departure from earlier PFS data, our teams nimbly modified designs and strategies to control cost increases and more accurately project business results.
The Challenge
Eskay Creek is a gold and silver open pit mine project located 83 km northwest of Stewart, BC. Once one of the highest-grade gold mines in the world before it closed in 2008, Eskay Creek was purchased by Skeena Resources, who turned to Ausenco for a PFS and Feasibility Study for reopening the mine. Several previously unseen challenges emerged during the FS, requiring new ideas and new designs to keep the project in line with preliminary financials, and give the client a clear view of anticipated capital costs, NPV, rate of return and other key metrics.
The Better Way
For the Eskay Creek study, we brought together a diverse international team of in-house expertise. In addition to the process, mechanical and civil/structural disciplines normally involved, we worked with our sustainability team, a dedicated snow management team, and specialized teams for ground and surface water work, geotechnical, waste rock design and tailings management.
With the addition of updated data from the metallurgical testwork program, we reran the metallurgy recovery predictions model - further derisking the project. The updated model results were in line with the PFS allowing us to optimize the flowsheet and firm up major equipment sizing (e.g. mills, flotation cells, filters etc.).
An efficient plant and site infrastructure layout were developed that considered the snowfall in the area, including a robust snow management plan. Our layout reduced the earthworks resulting in decreased construction timelines, blasting and the creation of PAG waste rock.
To mitigate and manage the effects of acid rock, and PAG waste rock from the pit, both tailings and PAG waste rock will be stored sub aqueously. The existing and permitted tailings facility (Tom MacKay storage facility) will be upgraded and expanded for the project through LOM. This approach protects regional ground water during the operation of the mine and following closure.
The weather and snowfall conditions of the location were considered while we developed the sequencing and timing of our detailed execution plan and schedule.
The Outcome
The ability of our global team to stay nimble and adaptable through the challenges allowed us to incorporate changes into the overall design with minimal capital cost implications. Our technical solutions resulted in a high ROI for our client.
The new operation is expected to reach a throughput of more than 3 Mt/y, with a total of 4.6 million gold equivalent ounces produced over the 12-year life of mine.