Ontario is becoming the first jurisdiction in Canada to have a dedicated regulatory pathway for projects aimed at recovering residual metals and minerals from mine waste.

Experts said the move is a promising step, but technical and economic hurdles still stand in the way of wide-scale waste re-mining efforts.

The province announced a regulatory change to the Mining Act in late November 2024 to create a permit process specifically for recovering metals and minerals from tailings and mine waste at open, closed or abandoned mine sites in the province.

The change will go into effect in July and will require permit applicants to submit recovery and remediation plans that detail how they propose to recover minerals and how they would remediate the land to a state that is “comparable to or better than” it was before. The government may require financial assurance as a condition of granting the permit, and noted projects will not be exempt from other provincial or federal requirements.

Certain lands will be excluded from potential mineral recovery activities, such as former uranium or asbestos mines with high environmental risks, or areas of the province that the government has spent money to rehabilitate.

A “rare” opportunity

George Pirie, the province’s mines minister, told CIM Magazine in an interview that the province believes there are substantial stores of critical minerals currently bound up in slag dumps. The province has estimated that there are “hundreds” of potential sites that host tailings or waste rock that could be available for mineral recovery. “Metallurgy and processing has changed significantly and recoveries have increased significantly. There was quite a lot of valuable material that was left in the ground,” he said.

Pirie said that one of the potential prizes is being able to extract rare earth elements (REEs) from mine waste. REEs are used in electric vehicles, wind turbines and consumer electronics, and roughly two-thirds of global production came from China in 2023, according to the United States Geological Survey.

“If the Chinese embargoed those rare earths right now, we would not be able to produce or manufacture any electric motors here. The opportunity, especially in these base metal mines, to recover those rare earths is imperative,” he said. “These areas will have infrastructure around them—smelting and refineries. There’s an urgency to develop this capacity.”

Some Ontario companies have started to explore the possibility. Junior company Nord Precious Metals Mining Inc., which in August announced it was seeking permits to reprocess the tailings of the historic Castle silver mine north of Sudbury, said in a Dec. 2 press release that it is “positioned to be [a] first mover” to take advantage of Ontario’s new strategy.

Vale granted $875,000 over five years to the Mining Innovation, Rehabilitation and Applied Research

Corporation (MIRARCO) at Laurentian University in March 2023 to support its research into biomining and bioremediation, as well as efforts to recover nickel and cobalt from pyrrhotite tailings. BacTech Environmental has also partnered with MIRARCO to develop a bioleaching pilot plant in Sudbury to recover nickel, cobalt, green iron and sulfur from mine tailings.

However, the economics may not be there yet for many companies. Aynsley Foss, manager of issues and policy for the Ontario Mining Association, said that while the association approved of the regulatory change and was heavily involved in consultations and workshops with the provincial mines ministry and that its members have started to look at the possibility of recovering minerals from their tailings in recent years, “at this point, it’s not super economically feasible to do these types of projects.”

Pirie acknowledged that some commodity prices have slumped, “but we think those price slumps are relatively artificial.”

More potential for waste re-mining

Karen Chovan, founder and CEO of Enviro Integration Strategies Inc., and the lead of the Tailings Working Group for CIM’s Environmental and Social Responsibility Society, told CIM Magazine in an interview that she hopes to see more provinces make similar regulatory changes. She thinks the new regulation could open the door to smaller players, like independent technology or processing companies, that want to explore potential mineral value in closed or abandoned mines. She noted language in the act now specifies that a recovery permit does not constitute the assumption of liability to rehabilitate a site and address all mine hazards.

“In the past, the minute you touch it, it’s on your plate if you do anything to it—even sampling was a problem, from what I heard,” she said. “[Previously,] if you had done some economics on tailings reprocessing and it looked like a good thing, but you later realized there’s an underlying environmental problem you never knew anything about, now you’re liable for that and all the good things you intended just put you in debt.”

Chovan said the language requiring applicants to remediate to a quality that is at least comparable to the site’s existing state also creates more potential for companies to engage in waste re-mining. A previous draft of the regulation allowed for re-mining only if remediation left the site in better condition than before. “In many cases, there’s an opportunity to go in and reprocess, but you may not be able to get rid of historic contamination problems that are already there. But you could fix the source and get rid of the source, so that opens a lot of opportunity,” she said.

A lack of historical data

Jamie Kneen, MiningWatch Canada’s outreach coordinator and Canada program co-lead, told CIM Magazine in an interview that the organization wants to see companies recover residual metals to improve the efficiency of mineral extraction and also as a way of minimizing environmental contamination. But he said companies looking into abandoned or closed sites may have little information on what has been left behind.

“From older operations, where they might’ve changed hands a few times, those records might not be there. We might need more of an inventory,” he said. “From a policy perspective, the province could be doing that work.”

Pirie said he expects consultants are currently “poring through” the province’s Abandoned Mines Information System, a database of past-producing mines that includes information on when they were in operation and the number of tonnes produced. However, he acknowledged the database does not include information on the mines’ recovery rates.

Operating mining companies will have a good understanding of the contents and geochemistry of their tailings, Chovan said.

However, even if companies have information on a past-producing site, that may no longer be accurate after years of weathering and leaching, she said. She also noted that characterizing tailings will be “more difficult” than characterizing ore bodies, because valuable minerals often end up in soft slimes: “It’s hard to tell where different commodities might actually be.”

Chovan also noted that any eventual recovery operations will need to have mills that can handle fluctuating material grades.