Underground mill proposed for Eagle’s Nest
Building an underground mine in one of the world’s largest wetlands regions 350 kilometres from the nearest transportation infrastructure poses several challenges. Without an obvious source of aggregate, how do you construct surface infrastructure, and with no roads, how do you get the ore to market?
Noront Resources, a junior mining company based in Toronto, faced these precise challenges following the discovery of its Eagle’s Nest deposit in the Ring of Fire, an 80 kilometre by 100 kilometre swath of muskeg in Northern Ontario that has been described as one of the most significant mineral bearing areas to be discovered in Canada.
“If (Eagles Nest) was beside a highway or a railway, it would be in production now,” Noront Resources president Wes Hanson told delegates at the MassMin 2012 conference in Sudbury earlier this summer. “Unfortunately, we are located 350 kilometres north of any existing infrastructure. We also happen to be located in the James Bay Lowlands, which is devoid of any topographic relief. There are no construction materials for aggregate, no rock outcrops. Building traditional surface facilities will be extremely challenging, so we’ve decided to construct our mill underground.”
Eagle’s Nest is a high-grade nickel sulphide deposit with 11.1 million tonnes of proven and probable reserves and another nine million tonnes of inferred resources.
The company made the discovery in 2007 by following up on anomolies showing up in airborne geophysical surveys.
“We went up there in 2007 to do a 10-hole drill program and the fifth hole hit what is probably the most significant discovery in Canadian history: 3.5% nickel, 2% copper and 15 g/t platinum and palladium,” said Hanson.
A number of junior mining companies flocked to the region, staked ground around the discovery and started their own exploration programs, which then led to the discovery of a huge chromite deposit.
“Between the different companies, we’re probably sitting at a total resource of between 150 and 200 million tonnes of high-grade chromite, and by high-grade, I mean better than 35 or 40 per cent. That’s a highly desirable product equal to anything that’s being mined in South Africa,” said Hanson.
“There may not ever be a city like Sudbury up there, but the Ring of Fire will certainly rival the Sudbury camp as one of the great mineral discoveries in Canadian history.”
Cliffs Natural Resources acquired the Black Thor chromite deposit from junior miner Freewest Resources in 2009 and is now proposing to spend upwards of $3 billion in anticipation of a production startup by 2015.
Noront’s chromite-bearing Blackbird property, two kilometres from Eagle’s Nest, lies at the southern extension of the 15-kilometre long chromite belt, and can be developed using common underground infrastructure, “but as a small Canadian junior mining company with a limited market cap, it’s very difficult for us to take on two projects simultaneously, so we decided to focus on Eagle’s Nest first,” said Hanson.
Noront Resources boasts that the Eagles Nest mine will have one of the smallest footprints of any underground mine in the world. Surface facilities will be limited to a road network, an airstrip, a camp, a portal facility and compressors. There will be no tailings pond, no mill, no warehouses. The total surface disturbance will be approximately 42 hectares.
“I even wanted to put the camp underground, but everyone else drew a line in the sand over that,” joked Hanson.
A 3,000 tonne per day mill and associated production facilities will be housed in a series of underground chambers 18 metres wide by 18 metres high at a depth of 170 metres in extremely competent rock.
Three million cubic metres of aggregate for the runway and surface facilities will be mined from underground for two or three years while construction is in progress.
“We’ll train our First Nation employees on mining waste, so by the time we access the orebody and begin commercial production in 2016, the labour force will be trained up,” noted Hanson.
Tailings will be recycled underground as cemented paste backfill into the aggregate stopes and openings in the orebody.
The deposit, which will be accessed by a twin decline system, has been traced to a depth of 1,600 metres and probably extends beyond that, “but at $1 million a drill hole, it’s very difficult for us to pursue it any further (from surface), so our plan is to expand the reserve as we develop underground,” said Hanson.
A pre-feasibility study completed last year estimated initial capital costs of up to $750 million, plus $150 million of sustaining capital over the life of the project.
Noront was originally planning to transport its nickel-copper concentrate via slurry pipeline to a proposed all-weather road terminating at Webiquie Junction 90-kilometre to the west, but a decision earlier this year by Cliffs and the Ontario government to build an all-weather road to the CN rail line 350 kilometres to the south provides Noront with a much more cost-effective means of transporting its concentrate out of the region for further processing.
The Ring of Fire lies in the traditional territories of nine remote First Nation communities struggling with 90 per cent unemployment, extreme poverty, and severe alcohol and drug dependency, providing Noront with yet another challenge given the requirement to consult and accommodate these communities.
“We want to see the First Nation communities benefit from the development of the Ring of Fire and we’re really focused on that in terms of our community engagement,” said Hanson. “We’re especially focused on educating the youth about mining and the opportunities that will be there for them in the future.
“This is one of the things that really sets Noront apart and it’s something we should all consider,” he told the 600 MassMin delegates. “We’re here talking about technological innovation, which is absolutely vital for the mining industry to move forward, but we also have to consider social innovation. We have to do things differently as an industry. We have to change the way we have operated in the past, both in terms of our environmental stewardship and our social responsibility.
“So, when I say Noront is building a model mine of the future, I’m not just talking strictly in the technical sense. I’m also talking about corporate responsibility.
“It’s our obligation to make sure that the communities are well-informed and by making them well-informed, you eliminate all the misinformation that environmental activists use to drive wedges between us.”
An environmental assessment of the Eagle’s Nest project is currently under way and a feasibility study is about to be released.
Tagged Black Thor, Canada, Cliffs Natural Resources, Company Expansion, Eagles Nest mine, Freewest Resources, junior miner, junior mining, M&A, Noront Resources, Northern Ontario Business, Ontario, Person Communication and Meetings, production startup, road network, South Africa, Sudbury, Sudbury camp, Sudbury Mining Solutions Journal, Toronto, underground infrastructure