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Island Gold Mine One of North America’s highest grade gold mines

Dec 11, 2022

Alamos Gold’s Island Gold Mine located outside of Dubreuilville, Ontario is one of the highest-grade gold producers in North America, and recently declared their million ounce pour in 2021. This was a major milestone for the mine but due to the Covid Pandemic couldn’t be celebrated the way it should have been. But that isn’t the end of the story for this operation, it is just the beginning.
Austin Hemphill, General Manager at Alamos Gold’s Island Gold Mine spoke at the CEN CAN Expo in Thunder Bay this past September where attendees were given a presentation on the Phase 3+ expansion project for their underground Island Gold Mine.  
The Island Gold mine is operating at about 1200 ore tonnes per day. With the Phase 3+ project, they’ll be expanding it to 2400 tons. For anyone following Alamos, they would have noticed they announced, at the peak of the 2020 pandemic, their initial Phase lll project which was to be a 2000 tonne/day project. Since then, Alamos has experienced ongoing exploration success. Due to that success, they’ve been able to expand that project (Phase 3+) to 2400 tons per day.
Right now, from an annual basis, Island Gold is spending about $60 million in goods and services and paying about $38 million in wages.  “Again, with about half of our workforce based locally. We are a responsible operation and work relentlessly to maintain a very stellar environmental reputation. We work closely with our first nations community partners, and we meet or exceed all the standards,” stated Hemphill.
Half of the workforce at Island Gold is local - and local to Alamos is the town of Dubreuilville and nearby White River and Wawa. They have about 824 people at the Island Gold mine and it continues to grow. The breakdown in the workforce is as follows; 481 employees, 340 contractors and just over 45% of their workforce, again are employees based locally, and about 7% of their workforce self-identify as First Nations. Right now about 18% of their workforce are female, and the majority of those being local. The mining average for female employment sits at 16% in Ontario. The workforce is getting younger, with 21% below 30 years of age.
Since Alamos acquired the asset in 2017, which at that time had just around 2 million ounces combined resources and reserves, they have more than tripled the resource. Alamos continues to have exploration success as they have acquired additional assets in the neighborhood. All of this positive shift contributed to why they decided to ultimately convert to the Phase 3+ project.
When Alamos acquired the Island Gold mine, the project was producing around 100,000 ounces of gold and currently they are producing around 140,000 ounces of gold per year. Once the Phase 3+ project is completed the company expects the number will double.
What this project will entail is a fundamental transformation of the mine site, they’ll go from their current ramp access only mine using a Modified AVOCA mining method to the Phase 3+ expansion project which will include the installation of a new shaft, installation of a paste backfill plant and an expansion of the current mill facility.  
The first element of the project will be the sinking of a shaft. “This is a new shaft and when we looked at this project in 2020 we identified we’re down to about 1500 meters with the identified resource and we said, okay, as we continue to have success we’ll adapt. So how deep should the shaft be? We went ahead and we designed the shaft, we designed the hoisting plant, we designed our ventilation infrastructure to take us down to 2000 metres.”


Austin Hemphill picture


Expansion to double gold production


Hemphill says this means Alamos is able to utilize hoisting efficiencies upon the initial depth, to just shy of 1400 metres. “That also gives us the ability to expand to the future. In addition to that, we’re going to construct ourselves a paste backfill plant. We’re going to be able to divert about 40% of our tailings underground providing us a longer life with our existing tailings storage facility. Right now, the design capacity, that facility has is adequate for everything we have in the books from a resource and reserve perspective. And then finally, obviously, we’re going to be mining more. We have to process more.”
Alamos anticipates completing the project by mid 2026. The Island Gold mine’s new shaft will be located south of Goudreau Lake. This will include the infrastructure, the shaft itself, admin buildings and dry facilities. 80% of the workforce is going to relocate south of the lake upon completion of the project.
The shaft production hoisting plant (ore and waste) will consist of a 5m x 2m double drum, a 2000 metre design depth with an initial sinking depth to 1373m, 2x 12t skips at 15m/s on steel guides, 4200kW rating, bottom dump skips with scrolls, 198s at 2,000m = 3,500 tpd, 154s at 1305m = 4,500 tpd and 54mm hoist ropes. This is a conventional steel head frame.
The newly designed service hoisting plant (personnel and materials) will consist of 4.5m x 1.8m single drum, 2,000m design depth, 2500 kW rating, 8t double deck cage with 33 persons per deck, 10m/s on timber guides with dogs used for personnel and palletized loads, 7.5 trips/hour at 1,305m (main shaft station) = 495 people per hour and 43mm hoist ropes.
“With respect to personnel getting to and from the workplace safely and rapidly at present we are ramped down to right around just over a kilometer deep, it takes them about an hour and 15 to an hour and 20 minutes to get from the portal to the working areas. The new shaft design will cut more than half that time moving them closer to 30 minutes to most of their working areas at the time of the completion of the project,” said Hemphill, which gives the company obvious production time boosts.
By utilizing the new design, they went a bit larger with an eight-ton cage with two decks which allows the mine to bring 33 persons per deck 66 people per load. This means they can bring their entire workforce down in about an hour or less meaning a huge savings to the mine. This isn’t a separate compartment; it’s going to be on timber guides and is counterweighted. They operate this independently, which provides the highest level of flexibility.
The next element of the project discussed during the presentation, was their paste plant, which is a $50 million project. The mine is a narrow vein mine and they have had to leave a lot of material underground as pillars. The Island Gold mine is a very high grade mine with an average reserve grade at about 10 grams per tonne, so the pillars have a significant amount of value to them. By utilizing their paste backfill, they get a number of benefits, they have an engineer fill product, they can increase their extraction ratio, as well as being able to divert about 40% of their tailings from the storage facility back underground.
The last aspect of the project is the mill expansion to 2400 tpd capacity. The key component changes are a new crushing plant, an additional ball mill, convert the existing circuit to two trains, refurbish the existing regrind mill, convert 5 leach tanks to CIL and add 3 new larger tanks, add a new packaged 5t ADR plant and new cyanide destruction circuit. The cost of the mill alone expansion is 76 million dollars.
“We have an existing mill, we have known metallurgy and we demonstrated we understand how to process our ore so we’re going to effectively twin our processing plant,” said Hemphill. “Again, we have a simple metallurgy so there’s no flotation or anything, so it’s a simple leach circuit. What we’ll do is effectively duplicate our existing 1200 ton ball mill. We’ll utilize one of our existing historic mills, we’re presently using as regrinds and have two parallel trains. We’re going to be utilizing a lot of the materials and resources we already have and re-tasking and repurposing them.”
The mine will require a truck load-out area and have the trucks tram ore up to the existing mill which is about a two kilometer haulage distance. The ore will be stockpiled to surface in a new storage facility. The company needed to add a cyanide destruction circuit using the natural photodegradation for a cyanide destruct. This will give more control over the process.
Alamos looked at options. “Everybody wants a new shiny mill, and they took a good look at it, but it didn’t make sense when you have an existing mill that works and works quite well. In addition to this, by paralleling it, we now have two trains, we have effectively a significant level of redundancy online. The advantage of expansion verses a new mill are two-fold. A lower capex and two trains provides greater operational flexibility.”   
Hemphill ended his presentation by underlining that this is a billion-dollar project. “We’re able to fund this project wholly from revenues and mining both from the Island Gold mine as well as our sister operations. In addition to that, we are looking to reduce costs from about $700-$800 an ounce all in sustaining, to about $340 going forward which is a significant reduction.”
In addition, the operation has become even more efficient from a greenhouse gas perspective. They are able to park the majority of their diesel fleet on the completion of the project and become almost completely reliant on grid power. As part of their project, they are now looking at how to better implement electrical equipment underground.
The project started with the new admin buildings and was completed in 2021. They built and constructed a new warehouse as they’re doubling their production and are going to double their demand on consumables.
Historically the Island Gold mine was a small operation, with a small shop at about 315m level. They have now relocated a larger shaft underground and the new shop is located at the 620m level.
With permanent camp work is done, the mine site has a little over 480 rooms right. There is also a temporary camp expansion required for the project.
Alamos has already begun their pre-sink. That’s the initial 50 meters of the shaft. Once completed, they’ll install the Galloway, construct the permanent head frame over it, commission the hoists and then begin sinking in earnest. It is believed the initial production from the shaft will be scheduled in Q1 2026 and it will continue to ramp up through the year into 2027 where they will reach their 2400 ton/day production rate.”


For this article and more visit the digital copy of: The Northern Ontario Mining Report

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