Montréal-based cleantech startup Exterra has raised $20 million in Series A funding to scale its technology that repurposes asbestos mine tailings into critical minerals and carbon capture materials.
The all-equity round was co-led by Clean Energy Ventures and BDC Capital’s Climate Tech Fund, with participation from Investissement Québec, MOL Switch, and Karpowership, bringing the company’s total funding to $32 million.
Extracting value from waste while mitigating health risks
Exterra’s process extracts industrial-grade silica, nickel, and magnesium oxide from asbestos-contaminated mining waste. The latter can be converted into magnesium carbonate through a carbon mineralization process that sequesters 1.1 tons of CO₂ per ton of material—enabling the company to sell carbon credits on the voluntary market.
Exterra’s dual approach not only removes hazardous materials but turns them into profitable, climate-positive products. CEO Olivier Dufresne emphasized that circularity in mining is “essential to fighting the climate crisis.”
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Québec facility to process 400,000 tonnes annually by 2027
With the new funding, Exterra aims to launch Hub One, the world’s largest asbestos tailings mitigation plant, by 2027. The facility will be located in Thetford Mines or Val-des-Sources, both former asbestos mining hubs in Québec. The plant will process up to 400,000 tonnes of tailings annually.
To prepare, Exterra is scaling its pilot operations and engineering studies while onboarding more industrial clients. Its current team of 13 is expected to grow to 20 in the next 18 months.
Business model combines materials sales and carbon credits
The company will generate revenue by selling magnesium oxide to industrial partners, nickel to EV battery supply chains, and carbon credits to buyers like Frontier Climate and MaRS. Notably, all of its available carbon credits have already been pre-sold.
Although shifting market sentiment has affected voluntary sustainability pledges, Dufresne says Exterra’s business is resilient thanks to its diversified income streams beyond just carbon offsets.
Complementing Canada’s climate innovation ecosystem
Exterra’s work complements other Canadian carbon tech ventures, such as Deep Sky, which is building underground CO₂ storage in the same region. Dufresne says “we’ll need every possible way to store carbon,” reinforcing the collaborative rather than competitive nature of the emerging sector.
With its transformative technology and fresh capital, Exterra is poised to redefine mining waste as a critical tool in the global decarbonization effort.
