Turning mining waste into climate solutions

CTC #132 - Exterra lands $20M to convert mine tailings into critical minerals and remove carbon.

Author

Justin Reist
May 13, 2025

Happy Tuesday!

Did you know that the world’s mine tailings - the finely ground rock and water left over from mining - hold about $3.4 trillion worth of critical minerals and metals?

Montreal’s Exterra is tapping into this overlooked resource with a fresh $20M Series A to turn Quebec’s asbestos tailings into critical minerals and lock away carbon.

We’re also introducing a new section this week where we’ll share some hand-picked ideas and insights from our community! We kick off with insights from Corey at Growcer, Arman from Properate, and our friends at RXN Hub.

What’s happening this week:

  • Active Impact Investments closes a $110M Fund III

  • Northland Power starts up its 250 MW battery storage project

  • And Ontario gives the green light to small modular reactors

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TECH

Turning Mining Waste into Climate Solutions

Montreal’s Exterra closed $20 million in Series A funding to turn mine tailings into climate solutions. Clean Energy Ventures and BDC Capital’s Climate Tech Fund led the round together.

The tech: The process starts by destroying the harmful asbestos fibres and then extracting nickel (used in EV batteries), silica (used in cement and building materials) and magnesium oxide (used for fireproofing or electrical insulation). The materials are sold to industrial customers.

Exterra can also convert the magnesium oxide into magnesium carbonate via carbon mineralization, locking CO2 away within the rocks and generating carbon credits. 

The result is a hybrid business model, generating revenue by selling materials to industrial customers and from carbon credits. Frontier and MaRS have already pre-purchased all of their credits.

Why it matters: Mine tailings are a significant and underleveraged source of critical minerals. There are close to 300 billion tonnes of tailings waste globally, with about 16 billion more produced each year.

Quebec alone has about 800 million tons of asbestos tailings from a long history of asbestos mining, much of which is clustered in two cities - Val-des-Sources and Thetford Mines.

These represent huge financial liabilities - about $10 billion for governments in Canada alone - that could become multi-billion dollar opportunities.

Re-processing the mining waste would be a major win-win. First, it helps reduce the environmental footprint, minimizing the risk to human and planetary health. And second, it expands Canada’s supply chain for critical minerals, generating new minerals without the need for new extractions.

What’s next: Exterra will use the fresh capital to ramp up to opening it’s commercial hub, which will process 400,000 tonnes of tailings each year. That includes running larger pilots, securing long-term offtake agreements, and gathering data.  

CLIMATE CAPITAL

💰 Active Impact Capital closed $110 million for its third climate tech fund. The fund will continue to back ventures across the climate spectrum with $1-4M cheques and plans to lead and price rounds, a common gap in the Canadian ecosystem. Active Impact has invested in Jetson, Audette, SWTCH and more. 

🔌 AlumaPower, Clockwork and e-Zinc are among 30 EV technology companies receiving a total of $56 million from the Ontario Vehicle Innovation Network and private industry to develop EV charging, powertrains, infrastructure and more.

IN THE FIELD

🗺️ Deep Sky is teaming up with Canadian Discovery to map CO2 storage potential across Eastern Canada, building the “infrastructure behind the infrastructure” for carbon removal.

🔋 Northland Power started commercial operation at its 250MW Oneida energy storage project in Ontario. The project, which came in $100M under budget, will double the energy storage on the grid.

♻️ Colorado’s Alder Renewables will build a first-of–a-kind Sustainable Aviation Fuel plant in Quebec with forestry company Groupe Rémabec, turning sawmill byproducts into SAF.

🧪 UCalgary will be the XPrize Foundation’s first international hub as it expands its physical presence, helping local teams deliver competition entries and connect researchers, entrepreneurs and investors.

💰️ Scotiabank will back carbon removal research with $1M over 10 years from its Climate Action Research Fund.

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ECOSYSTEM VIEW

💡 Ideas & Insights

We’re highlighting perspectives across our climate tech community - essays, insights, research and more. Got something to share? Let me know!

🚧 Properate founder Arman Mottaghi joined me on the podcast to talk about bootstrapping a company, building science, and what needs to change in Canada’s retrofit ecosystem. Listen here.

“We found that it was a lot easier to just find incredible customers, people who were willing to put their money into the work, help us develop the platform and answer the tough questions.

And we kind of naturally we stopped having those investor conversations and started having more of the client work and making money … I think it's really great that our company is not beholden to anybody else other than our customers and our employees.” - Arman

🌱 Growcer CEO Corey Ellis shares his thoughts on what the fall of Freight Farms means for the vertical farming sector, and how they’re working to support farmers caught in the middle

📬️ Check out the More Vibrant newsletter by reader Sarah Lazarovic, an un-depressing newsletter about how to fight the climate crisis.

🌏️ Climate tech startups are looking to diversify into new markets, and Asia is a top contender. Our friends at RXN Hub and Ecosystem 17 just put out a report mapping market opportunities in Japan for Canadian climate tech.

NEWS

📡 Signals & Currents

⚛️ Ontario approves G7’s first SMR: The province approved plans from Ontario Power Generation to build the first of four small modular reactors at the Darlington nuclear site. The GE Hitatchi BWRX-300 reactor will power the equivalent of 300,000 homes and be the first in the G7 once built.

💬 Why it matters: The project could set the tone and pace for SMRs. Governments around the world - and across Canada - are watching the project to see how it goes, and whether SMRs are ready for prime time.

BC launches full CleanBC review - the program’s emissions goals are still off track.

Quebec wants more solar power - the 300 MW tender is focused on small-scale plants for now.

NS fast tracks clean energy projects - biomass, SMRs, and clean fuel will get accelerated reviews.

Alberta pauses industrial carbon price indefinitely - Smith wants to “keep industry competitive” in the face of tariffs.

Heat waves primed for blackouts - extreme heat could cause supply shortages in a major US grid.

Orsted cancels UK wind project - supply chain costs outweigh UK subsidies and price guarantees.

EU delays emissions rules for carmakers - the change creates breathing room from Chinese and US competitors.

Panasonic pivots to clean energy, storage - the company will cut 10,000 jobs in other areas to double-down on its clean energy business.

COMMUNITY

🗓️ Climate Global 2025 @ WebSummit Vancouver: Kick off Web Summit with a high-impact, one-day event connecting startups, investors, and industry leaders in climate technology. May 26th, Vancouver.

🗓️ Turning Food Waste into Value: Join me for an in-depth discussion with FoodCycle CEO, Bradley Crepeau, on building circular food systems. May 29th, Ottawa.

➡️ Discover more climate events.

🧑🏻‍💻 Adaptis is hiring a Product Manager to lead the development of their decarbonization platform.

➡️ Find more open roles.

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