Toxic tailings discarded at some 10,000 abandoned mines together with those currently being produced by 200 others in operation across Canada could hide a multi-billion-dollar market opportunity as demand for critical minerals explodes globally in the coming decades, a new study has concluded.
Tailings — a byproduct of large-scale mining operations — could be changed “from a liability into asset” by monetizing recovered minerals and metals from current waste for use in renewable energy technologies, data centres, and defence applications, said the report from Action Canada, a leader development programme.
There would also be a win-win beyond the financial in “re-mining” this huge network of decommissioned and operational mines. Removing tailings, which can pollute soil and water tables, would have a positive environmental impact, and redevelopment would aid in reconciliation efforts with Indigenous populations whose land neighbours much of Canada’s mining heartlands.
“Re-mining these tailings would be multiple birds with one stone,” said Lisa Mah, one of the authors of the study, produced with the Public Policy Forum, an Ottawa-based thinktank. “For energy security, national sovereignty, for the green transition, now the AI race, it’s all coming down to access to critical minerals.”
Canada currently generates some 650 million tonnes of geological waste each year from its mines — 70 per cent of which report substantial environmental risk from collected tailings. The sector has more than $10 billion in liability costs linked to treatment of tailings, according to number crunching from Mirarco, a research arm of Laurentian University in Sudbury, ON.
However, Mirarco also figures that billions of dollars in critical minerals were being left untapped. It calculated, as an example, some $8-10 billion in nickel from mines in the Sudbury area had been left in tailings piles.
Miner Rio Tinto recently set up a collaboration called Regeneration, with Resolve, an engineering consultancy, to explore re-mining and reprocessing of nickel tailings, waste rock and water to extract critical minerals.
The re-mining numbers might be even more tantalizing for Canada’s copper, a commodity metal that is often found in deposits that also contain key critical minerals such as tellurium, rhenium, cobalt, and indium. In 2023, almost 510,000 tonnes was mined from 39 active facilities.
But there are almost 1,000 so-called orphaned and abandoned mines where copper was the main raw resource extracted — and other metals discarded instead of being extracted and refined.
The Minerals Research Institute of Western Australia puts the global market for precious, critical and strategic metals in tailings at over US$3.4 trillion. The value is only set to rise as market pressures grow – not least due to U.S. President Donald Trump’s targeting of Canada, and Greenland and the Ukraine - for critical minerals reserves, in order to help divert U.S. economic and defence supply chains away from Chinese primacy.
Though the operational costs of re-mining are expected to be significantly lower than greenfield projects, given there is no mine to build, no rock crushing, no milling involved, the concept remains “undeveloped,” said Mah. “Domestic initiatives are limited and the adoption of innovative technologies is lagging.
“There are some pilots in Northern Ontario, in the Ring of Fire, that are starting to look at monetizing this, but it is all early-stage.”
No mineralogy or mine infrastructure
The Canadian government has built up a database listing the orphaned and abandoned mines and identified associated tailings sites. But there is nothing in these files on the mineralogy of these tailings, nor about mine infrastructure that may or may not exist today.
“This would of course be crucial to any re-mining initiatives’ insight into profitability, sustainability or regulatory compliance,” said Mah.
B.C. is the first province in Canada to have such an inventory. GeoscienceBC, a consultancy, recently published a searchable digital platform to catalogue mineral deposits and mine tailings using information sourced from the Abandoned Mines branch of the B.C Ministry of Mining and Critical Minerals.
“If every province did this it would absolutely accelerate the market opportunity,” said Mah. “Right now, how can anyone even do a basic profit-or-loss [analysis] on a re-mining project?”
Ontario has emerged as a market spearhead, last November introducing new regulation under the Mining Act to streamline recovery of residual metals and minerals from mine waste at both abandoned and active mine sites.
Time to build the ‘midstream’
Marilyn Spinks, director of operations at the Canadian Critical Minerals and Materials Alliance, an industry body, believes Canada must start by “building the midstream” — the processing and manufacturing part of the mining supply chain — and identifying main critical mineral buyers, while determining where the richest tailings are to be found.
“You must start with the demand. There is such a spectrum of critical minerals — batteries alone can need a range of different metals, for instance — so you have to know where your real demand will be and who your future customers are, before you can move forward,” she said.
“But you don’t need a mine to develop the midstream. If we do critical mineral mining right, from clean-sheet projects to re-mining of old tailings, it will rise because it will be based on a ‘demand-pull’ market."
Spinks added that re-mining was an opportunity for Canada to move beyond its commodity metals history. “The commodity supply chain-based push has served Canada quite well to this point, but the energy transition markets don’t work that way. We must keep a high-value manufacturing lens on this.
“Mining is a ‘brown’ [carbon-intensive] industry," she added, “But we can make it green, or at least ‘less brown’ with innovation.”
Technological advancements will be fundamental to Canada capitalizing on this overlooked critical minerals resource for several reasons, said Liam Hilder, minerals stream lead at the University of British Columbia’s Creative Destruction Lab.
“Technology can improve the economics in two key ways: enhancing the ability to analyze tailings composition and developing more cost-effective recovery methods,” he said, noting that innovations in sensor systems could soon be helping the mining industry measure tailings’ mineral content at scale in real time.
Technology boosts economics
“This would certainly help in strengthening the economic case for treating tailings as valuable assets rather than waste,” he said.
Additionally, progress in processing techniques such as biomining — also known as bioleaching, the extraction of metals from a low-grade ore using microorganisms — could increase recovery rates while lowering costs and “further improve the feasibility of tailings reprocessing”
Mah underlines that the value of re-mining to Canada's reconciliation process should not be underestimated. “There should be a heavy emphasis if we are working out the economics of extracting critical minerals from mines’ tailing on the reconciliation and land reclamation side too.”
She points to the 600 Indigenous communities living within 100 kilometres of large mines’ tailings pits: “This has to be a key consideration in looking at the potential of this market. Converting liabilities to assets, for financial gain but also the greater good.”
In a bid to ramp up mining of critical minerals, Ottawa in 2022 announced $3.8 billion in federal funding to finance geoscience and exploration, mineral processing, manufacturing and recycling applications, as well as research and development.
And last year, Canada’s critical minerals list was updated with three new materials, bringing the total to 34.
“It goes far beyond making critical minerals from tailings a complementary way to meet demand,” said Mah, highlighting Action Canada’s chief recommendation in its report, to build a National Tailings Inventory.
“No one can know how much [critical minerals from tailings] can contribute until we have a clearer idea of where the biggest reserves are and what it will cost us to get it processed and to market,” she said.
“No data, no decisions. Despite what is clearly a massive economic opportunity here, without better data there are no ‘next steps’.”
Darius Snieckus / Local Journalism Initiative / Canada's National Observer
Correction: The 10,000 mines referred to in the Action Canada report are classed as 'abandoned' rather than 'decommissioned'. Our article has been amended to reflect this distinction.
Comments
Thank you for the "650 million tonnes". When people decry the amount of mining we'll have to do for the green transition, they often don't understand just how much mining we already do to enable their lifestyle.
One wonders whether the end of this century will see a total collapse in mining, because the human race has stopped growing; most economies are hitting the point where improving efficiencies are greater than economic growth; and recycling of existing metals has greatly improved.
This sounds like a fundamentally good idea. But we shouldn't go too far overboard--just because you take a bunch of tailings and find that some of the stuff in that heap of toxicity are valuable, doesn't mean what's left afterwards will no longer be toxic at all. Probably less toxic, or at least smaller, but the devil's in the details.