As global demand for copper, lithium, and other critical minerals climbs, Canada’s mining industry is experiencing a subtle but consequential shift. In Q3 2025, companies and policymakers increased their focus on re-processing historic tailings, the mine waste once considered worthless, to recover valuable metals while reducing environmental liabilities. 

Toronto-based mining executive David Birkenshaw says the growing attention to tailings reflects both technological progress and changing policy. According to an August 2025 Reuters review, mining giants and mid-tier firms are piloting tailing projects across the country. Hudbay Minerals is evaluating legacy tailings at Flin Flon in Manitoba, while Rio Tinto has extracted rare metals such as scandium and tellurium from existing waste sources. Global tailings production now exceeds seven billion tonnes per year, and a significant portion of this sits in Canadian sites that reflect decades of lower-grade processing. 

An independent research report published earlier this year, Waste Not: Unlocking Critical and Strategic Mineral Opportunities in Canada’s Tailings, estimated that repositories across roughly 10,000 abandoned and 200 active mines contain multibillion-dollar quantities of minerals essential for the green economy and national defence. The report urged the creation of a national tailing inventory, streamlined permitting, and new policy approaches to shift tailing from waste management to resource recovery.

The evidence suggests that tailings re-processing offers both economic and ecological benefits. Modern flotation, hydrometallurgical, and microbial techniques can increase recovery rates by as much as 20% compared with historic methods. Glencore’s ISAMill for coarser grinding and its Albion leaching process are examples of how copper recovery can exceed 99% while reducing energy and water usage. Beyond extraction gains, re-processing helps mitigate long-term liabilities. Legacy ponds can pose environmental risks through leaching or dam instability. By re-mining deposits, operators can shrink tailings volumes, limit contaminant spread, and reclaim land more effectively. 

Birkenshaw explained, “Canada’s tailings legacy is not just a liability; it represents a missed resource. With current technology, we can turn that legacy into reclaimed value without the impacts of new development. In many cases, re-processing tailings is faster and lower-risk than permitting new mines. It is a smart path forward for both industry and communities.” 

Regulators are starting to adjust frameworks to encourage this approach. Ontario’s Building More Mines Act, passed in 2023, included provisions that allow conditional closure plans and streamlined permitting for tailings recovery projects. At the federal level, policymakers are considering ways to treat tailings as a resource rather than a burden, echoing the recommendations made by independent experts earlier this year.

Birkenshaw observed, “Regulatory change is essential. When governments recognize tailings as a resource rather than a burden, project economics change dramatically. We are seeing interest from Indigenous nations, mid-tier companies, and juniors that previously would not have access to capital.”

Technology is central to this shift. Dry-stack tailings, paste backfill, real-time monitoring using AI, and microbial extraction methods are now reducing water use, energy intensity, and overall environmental footprint. A recent case study noted that modern flotation can recover copper concentrations of 0.1 to 0.5% that would have been uneconomic under older systems. With multiple-metal recovery and digital optimization, such projects can be viable within one to three years, compared with the eight to ten years often required for greenfield mine development. 

The social and economic context is equally important. Many Indigenous communities are located near legacy sites and stand to benefit from remediation investment, job creation, and land reclamation. The Waste Not report emphasized that re-processing can support local economic development while restoring ecosystems and empowering communities that have long carried the environmental costs of mining. 

Recent data illustrate the scale of opportunity. Canada produces over seven billion tonnes of tailings annually. Across abandoned and active mines, tailings repositories contain quantities of critical and strategic minerals that could be recovered with today’s technology. Advanced processes can improve recovery rates by up to 20%, and regulatory reforms such as Ontario’s Building More Mines Act now allow recovery from tailings under conditional closure plans with faster approvals. 

By the end of Q3 2025, tailings re-processing moved from concept to action in Canada. It offers a way to recover critical minerals, reduce environmental liabilities, and engage Indigenous and local communities, all while lowering capital requirements and shortening timelines compared with new mine builds. As Birkenshaw summed up, “The convergence of technology, policy, and practicality means tailings re-processing is no longer theoretical but an actionable, near-term strategy. We can mine smarter, cleaner, and more responsibly.”

For Canada, a country balancing climate objectives with the needs for resilient supply chains, tailings re-processing may become one of the defining practices of the next decade