As part of its commitment to Goldcorp’s ambitious 20/20/20 growth targets, the Musselwhite mine in northern Ontario is in the throes of a major upgrade to its materials handling infrastructure, which promises to increase throughput levels, improve efficiencies and significantly reduce mining costs.
Musselwhite has a very shallow dipping orebody. Initial gold production in 1997 was trucked to surface from shallower mine depths of 500-600 metres. The first major expansion, which included an underground crusher and conveyor to surface from the 400 metre level (mL), was commissioned in 2002 as a result of deeper mining and longer haul distances to surface.
The mine has now grown to a depth below 1,200 metres under Lake Opapimiskan with a one-way haulage distance of 7.5 km to the 400 mL crusher. This requires a truck fleet of 17 45-tonne haul trucks to transport the ore to the crusher.
“As we go deeper, we need more ventilation underground in order to accommodate the trucks, which increases costs,” explained Richard Blakey, Project Manager of the Musselwhite Materials Handling Project. “By bringing in more trucks, there’s more congestion on the underground road. It simply got to the point where a more economical and efficient materials handling solution was needed.”
Geographical limitations of operating a mine below a lake rules out construction of a shaft to the surface to improve transportation and ore processing capabilities. Instead, Musselwhite embarked on a $90 million capital project to improve materials handling by constructing a raisebore winze which will dramatically reduce truck haulage to the mine’s underground crusher.
The project involves excavation of a winze, a vertical shaft inside the mine connecting to lower levels, which will be used exclusively to hoist ore from the 1,250 mL to the 280 mL exploration ramp level where the ore will be hauled by truck to the existing 400 mL conveyor. Infrastructure at 1,250 mL will include a dump pocket with rockbreaker, coarse ore bin, new jaw crusher system, fine ore bin and skip loading facilities. The winze hoist will have a capacity of 5,000 tpd at 100 per cent availability (4,300 tpd average). When completed, the new materials handling system will significantly reduce reliance on trucks, improve energy efficiency, reduce ventilation requirements and lower costs.
“This is a state-of-the-art materials handling system that will be operated at surface,” stated Blakey. “The automated rockbreaker, crusher and hoisting system will enable continuous operation between shifts, increasing efficiency and improving production levels.”
Construction commenced on the winze project in September 2016 with completion scheduled for the end of 2018. All major production equipment has been secured including a Davey-Markham hoist previously used at the Eleonore mine.
“It’s an exploration shaft hoist that was no longer being used at Eleonore. We identified this as an asset we could use at Musselwhite. It’s being refurbished now and is going to be a central part of our operation,” explained Blakey.
A set of ore passes are currently being constructed to move materials down to the 1,170 mL truck dump level. Major drift excavations including the main decline to winze bottom, truck chute access and bottom crusher access are currently underway. Chamber and bin excavation has started in the sheave deck, hoistroom access and crusher. The first ore pass raise was pulled successfully and contractors are in the process of installing necessary safety precautions prior to completing the 1,170 mL truck dump.
The project’s main contractor, Redpath Mining, carried out most of the lateral and vertical development work, as well as the construction and installation of the new processing facilities.
Particular emphasis was placed on integrating a full team of mining contractors into Goldcorp’s safety culture, said Blakey, which was a key factor in the mine achieving a 270-day triple-zero safety performance.
The winze materials handling system is scheduled to be fully operational by the first quarter of 2019. Once up and running, the new system is expected to increase throughput, as well as generate cost savings of approximately 10 per cent over the life of the operation.
The system will reduce the number of trucks operating in the mine from 17 to 9, minimizing traffic congestion and associated safety risks. Less ventilation will also be required, reducing power consumption and helping lower mining costs.
Todd White, Executive Vice President and Chief Operating Officer said, “In the big scheme of things, the materials handling project is a relatively small investment for Goldcorp that could potentially result in around a 20% increase in throughput at Musselwhite mine and unlock more of the operation’s potential.”