How a copper mine in Minnesota threatens a major Ontario provincial park
Why are we hearing nothing from provincial or federal governments?
I have never been to Quetico Provincial Park, west of Thunder Bay, Ontario; I have done my canoeing in Québec and Algonquin Provincial Park, and we have a family cottage near Dorset, about 40 kilometres from the West Gate of the park. Quetico is remote, and I am told, spectacular.
I wonder what the uproar would be like if a big Chilean mining company proposed a huge sulphide-ore (sulfide in the USA) copper mine in the middle of Muskoka, 40 km from the park. That’s what’s happening 40 km south of Quetico, on Birch Lake, just outside of the Boundary Waters Canoe Area Wilderness (BWCAW) in Minnesota. Of course, many have protested it since 2010; President Obama proposed a 20-year mining ban; the Biden administration formalized the ban, and in January, the House of Representatives voted to overturn the ban.
Coincidentally, while I was researching this post, The Globe and Mail published a long story, Boundary Divide, in which Nathan Vanderklippe focuses on how the mine might affect the dying community of Ely. The story is much bigger than that and affects a big chunk of Canada.
The mine is located just north of the Laurentian Divide, which separates water that flows south to the Mississippi or north to Hudson Bay. The Boundary Waters Canoe Area and Quetico Park are the same wilderness. Any polluted water from the mine will flow from Birch Lake into Lac La Croix on the border, to Rainy River, to Lake Winnipeg, to the Nelson River, to Hudson Bay.
How does this mine operate?
To understand how much water is used and what kind of pollution is produced, we have to walk through how this mine works.
In the rush to find copper, miners are going after lower-grade ores. According to a Twin Metals press release, the chalcopyrite being mined here is 0.59% copper. 99.4% of what comes out of the mine remains behind as tailings.
The mine itself is composed of giant spiralling tunnels with diesel-powered trucks carrying rock to the surface, 20,000 tonnes per day. Much of the ore has to be left behind as pillars to support the tunnel roofs.
When sulphur-bearing rocks are exposed to oxygen and water, you get sulphuric acid. A 2018 study claims "Most of the waste rock and pit wall rock would contain some sulfide sulfur, mainly as mineral pyrrhotite, which can produce acid leachate and soluble metals when it oxidizes." This mine is being built in an area that is one of the wettest wilderness watersheds on the continent. Controlling water will be the biggest challenge here.
After it is trucked to the surface, the rock is ground to talcum-powder-like dust in giant grinding mills. The powder is mixed with water and chemicals and air is bubbled through the slurry. The metal-bearing particles repel water and attach to the air bubbles and float to the top where they are skimmed off. The tailings sink to the bottom and are pumped away as a slurry. The tailings are rich in another iron sulphide rock, pyrrhotite.
It takes a lot of water, probably a thousand litres per tonne of ore. According to Mining Technology, “The crushed ore from the polymetallic mine will be sent to a 50,000t/d capacity concentrator plant proposed to be located 2.5 miles west of the underground mine site.”
That slurry containing 99.4% of the rock has to settle in tanks and be filtered. Half of the tailings will be pressed down into “filter cakes” and stored in a tailings pile somewhere, where they will be exposed to Minnesota rain and snow. As the tailing pile gets higher, it squishes more water out of the lower cakes. But don’t worry, Twin Metals says it will be on a plastic liner, and they will catch it all.
The other half of the tailings will be dumped back into the mine; Twin Metals says they will plaster the walls with it to reduce water infiltration. Whatever water gets in will have to be removed with pumps.
Can this actually work without acidifying everything?
There are many examples of sulphide ore mines that have become Superfund sites. Iron Mountain in California, which closed in 1963, is still leaking the most acidic water on earth with a pH of -3.6. The Berkeley Pit in Montana is filled with water and now requires a treatment plant that has to run forever.
Many Canadians will remember the story of Sudbury, where 7,000 lakes were acidified. That was airborne sulphur dioxide; now we are talking waterborne, but the end result is similar: acidified lakes. As Natural Resources Committee Ranking Member Jared Huffman told the US Congress,
Twin Metals, owned by Antofagasta, a Chilean mining company with close ties to China, has been lobbying to set up a mine outside the wilderness area, along the banks of waters that flow north directly into the wilderness. The type of mining Twin Metals has proposed has a 100 percent track record of toxic pollution. 100 percent. There has never been a mine of this kind that did not leach toxic pollution.
Where are the Ontario or Canadian Governments?
The Save the Boundary Waters people are asking this question. They remind us that there is a Boundary Waters treaty signed in 1909 that explicitly states “that boundary and transboundary waters shall not be polluted in either country to the injury of property or health of the other country.”
We certainly won’t hear anything from Ontario’s Doug Ford, who never saw a mine he didn’t like, but the feds? They apparently filed a memo. According to a 2020 article in Politico,
Deputy Prime Minister Chrystia Freeland said last month that the Liberal government is “very engaged” on the issue, though she offered no specifics. “It’s a proposal for a future project and it’s something that Canada definitely is involved in and will continue to work with our American partners on,” she said.
I have not found anything more recent.
This is not the first time I have discussed copper. The conventional wisdom is that if we are going to electrify everything, then we have to dig everywhere now and find more copper and aluminum. I can’t think of anything better to say other than the conclusion of my previous post:
We could practice sufficiency and simply use less stuff. We could go for micromobility instead of SUVs. We could go low voltage DC and cut the copper in construction in half. There is no copper in shoes; we could design walkable communities. We could put some efficiency standards on AI.
If you don’t like the words “degrowth” or even “sufficiency,” call it “demand-side mitigation.” The point is, we don’t have to live in a world where demand always exceeds supply; we can choose instead to reduce demand. And at some point, as the supply of resources gets tighter and more difficult to extract, that choice will be made for us whether we like it or not.
And we certainly don’t have to schlep 20,000 tonnes of rock every day to extract the half a percent of copper in it while acidifying the Quetico-Superior watershed. This is just stupid.
As an American opposed to this copper mine I can only say thank-you for Canadian support. We have a global problem that requires some response by all of us who think holistically: most governments and economists place the economy as priority number 1, failing to recognize that life and economies, depend on healthy ecosystems. If you destroy an ecosystem to maintain an economy, it is likely that the economy will collapse because the ecosystem that supports it is gone. The Boundary Waters, and Quetico, are purifiers, protectors and suppliers of an ecosystem service essential for life: fresh, pure and abundant water. Yes, copper has to come from somewhere. It may be that we have to learn to live with less (and reuse and recycle more), if not we may fail to live. It is that stark.
I read the Globe article you mentioned. Not a bad article but it followed a typical formula: one side says the environment is precious and tourism is a big part of the local economy, the other side says a mine will bring more well-paying jobs. Your article gives a lot more insight into the long-term and far-ranging environmental consequences, as well as the business-as-usual logic driving the mining project.