In a recent article, Trevor Eagles, Redpath Area Manager at Redpath outlined the company’s extensive development role at Goldcorp’s Musselwhite mine, the fly-in, fly-out operation located approximately 500 km north of Thunder Bay, Canada. There is a 750 km road to the site, which is primarily used to transport material and equipment. Ore is mined from two main zones below Opapimiskan Lake and is processed on site using a circuit that includes crushing, grinding, leaching by cyanidation, carbon in pulp recovery, and electrowinning.
During the recently completed development phase, there were approximately 120 Redpath employees at the mine. Shaft equipping and construction has seen a ramp-up to approximately 150 Redpath employees. The project start-up was in September 2016, and the scheduled completion date is January 2019, for a total of 28 months. Redpath provides manpower and equipment to develop 2,750 m of ramp and drift; excavate 23,500 cubic metres of large chambers, raisebore a 720 m shaft, raisebore 500 m of vent raises and ore passes, and construct the hoist, sheave deck and crusher, as well as equipping the shaft and the ore flow system.
Access to the underground workings is by ramp with an orebody that trends north and dips at a 30-degree angle. Production started in 1997 and the main production zones are continuing to advance further and further away from the original portal and infrastructure. Ore is currently transported a distance of 7.5 km from the active mine workings to the underground crusher – a one hour round trip for a large fleet of haulage trucks. The extensive haulage distance, large fleet of trucks, and the high demand on the ventilation systems, has led to the development of Musselwhite’s Material Handling Project.
“The primary objective of this project is to reduce the number of operating trucks, and thusly, the high ventilation quantities and associated cost required to support the fleet. The Material Handling Project will also provide an opportunity to increase daily production.” Redpath was awarded the brownfield Material Handling Infrastructure project, and commenced planning for mobilisation and start-up through late spring and summer of 2016, with mobilisation beginning in September. The first year of the project was scheduled primarily as a development project with the remainder of the project dedicated to equipping the shaft and the construction of the hoisting and ore flow systems.
“Despite extensive planning prior to mobilisation, the project start-up was not without its own set of challenges. The client was inundated with the large influx of workers, and insufficient charter flights and limited bunk-house space caused additional delays. Further complications included several changes made to the scope and mine design, during the ramp-up period. Any major expansion in an operating mine environment poses its own set of complications relating to the prioritisation of capital work against the daily operating requirements. After the initial start-up challenges were resolved, the lateral development portion of the project reached a successful completion in April 2018. Numerous compliments on the high level of quality of the work and engagement and commitment to safety witnessed in the team, were expressed by the client. As of mid-May, much of the development crew had taken on other areas of the Material Handling Project, or moved on to other projects. The Material Handling Project scope contains over 1,200 m of raisebored vertical development, and included in this portion of the project is the large diameter (5.5 m) production shaft. The shaft is being bored in two sections utilising two Redbore 90 drills. Two long ore passes are also to be developed, as well as vent raises and pilot holes for three ore bins.”
The upper portion of the raisebored shaft was recently completed, despite ground conditions proving to be more
challenging than originally expected. The Redpath raisebore team was supported by the development and construction teams and successfully worked through these issues, demobilising the Redbore 90 drill in April 2018. In June 2018, the lower section of the raisebored shaft was still being excavated and continued to encounter areas of poor ground. Construction crews assembled the galloway and sheave deck, and installed the sinking winches in April and May of 2018.
“Redpath crews moved on to ground support installation in the shaft, and excavating the skip dump slashes. Installation of the steel sets and guides in the upper portion of the shaft will follow, as will the continuing development of ground support down to the loading pocket area. This work is on the critical path and progressing as planned. Forecasted completion of this portion of the project is scheduled for late 2018.”
A notable innovation at Musselwhite was the introduction of Sandvik’s AutoMine technology. This system allows the operation of an LH514 LHD from surface, either in tele-remote or full automatic mode. Redpath’s trained operators gain back several hours per shift by mucking through regularly scheduled shift changes/blast windows from surface. Development crews would have their headings cleared of blast rock when they arrived at the beginning of their shift, and the shaft raiseboring would not be delayed when mucking. Development productivity benefitted greatly by effectively adding several hours of face time per day in locations where the AutoMine system was installed.
In April the mine development fleet is now in the process of being demobilised. Some delays relating to the spring half-load weight restriction on the site access road slowed progress slightly, but it was expected that the development fleet would be fully demobilised by June 2018. “The transition to full infrastructure construction is nearing completion, with multiple workplaces active and progressing on a 24/7 schedule. The civil/structural work in the hoist room and sheave deck locations are essentially completed. Approximately 500 cubic metres of concrete has been poured, and an overhead crane has been erected in the hoist room. The mechanical crews are beginning the hoist installation, while the electrical crews are working on cabling and switchgear.”
In addition to the hoist room, the underground crusher installation which includes the installation of two cranes,
a chute and feeder system, a jaw crusher and the conveyor system to the fine ore bin, has begun. This will be one
of the largest builds on the project and is scheduled to take nearly five months to complete. Other construction areas include a rockbreaker with a truck dump and ore pass chute; the loading pocket and fine ore bin load out/conveyor; the ore transfer station; several doors and ventilation controls as well as the shaft bottom sump.
“Recruiting an experienced workforce in an increasingly competitive market is an ongoing challenge. Redpath’s recruitment team located in North Bay have been extremely helpful in providing quality resumés and finding qualified mining professionals. Another major, although not uncommon challenge, is logistics. Millions of dollars
in permanent equipment and material are being transported to site, moving through a connected underground ramp
system on a ‘just in time’ basis due to limited laydown and storage space on site. Support received from Redpath’s
logistics team is helping this portion of the project run very smoothly. A good safety record with no lost time injuries to date has been a highlight of this project, and having an engaged workforce has been key. Numerous compliments from the client on Redpath’s safety huddles as well as the quality of the work have been expressed. The client has indicated confidence that Redpath will continue to meet and exceed expectations and complete the project with success.”
