Canadian miners extract critical minerals from asbestos tailings

According to the Mining Journal, Olivier Dufresne, CEO of Exterra Resources, revealed that the company is extracting magnesium oxide, nickel, and silicon from abandoned asbestos tailings at mines using a certain technology. This approach not only secures a supply of critical minerals but also enhances the environmental benefits of the mines.

Dufresne, a former mining engineer and investment banker, founded a tech startup three years ago to develop and commercialize technology for extracting critical minerals from tailings.

Headquartered in Val-des-Sources, Quebec, Canada, the company changed its name from "Asbestos" to its current name in 2012. It has acquired tailings from two major asbestos-producing regions in Quebec, totaling 130 million mt, with a magnesium oxide content of 39%, silicon content of 39%, and nickel content ranging from 0.2% to 0.3%.

In addition to extracting metals, this process also reduces environmental pollution.

"The community and authorities expect us to ensure the removal of all asbestos fibers. We achieve this by adjusting acid dosage, increasing temperature, and extending the process time. The good news for the community and the government is that over 90% of the asbestos fibers can be converted into high-value commodities."

The nickel component is in the form of mixed hydroxide precipitate (MHP), which can be further processed into raw materials for lithium-ion battery production.

Magnesium oxide is the main product, used to manufacture refractory bricks, flame retardants, and magnesium-based cements. It can also be used to produce other metals through low-carbon hydrometallurgical processes. Additionally, magnesium oxide can be used to sequester carbon dioxide.

"The first step in commercialization means focusing on high-income markets, which implies that while other markets are not unlimited, sequestration could be."

Exterra has just commenced construction of a pilot plant to prepare data for the FEL-2 front-end engineering design, which will be completed by the end of the year. A feasibility study will be conducted in 2026, with construction set to begin in 2027.

Acid Regeneration

Exterra leaches metals into solution using acid, then precipitates the valuable metals, leaving behind acid and magnesium oxide (or calcium oxide, depending on the raw material).

A key factor in this technological process is its ability to regenerate the acid it requires.

"The process can use any acid. Initially, we used nitric acid, which was very expensive at $600/mt. Our Fel-1 study showed that we could regenerate this acid at a cost of $75/mt, a 90% reduction in cost."This presents many opportunities for new ores, including those that cannot fully recover enough metal due to the high cost of acid," said Dufresne.

With numerous tailings piles in Quebec and other parts of the world, Dufresne believes there is significant potential.

"Mining companies need to reduce tailings, which often contain calcium or magnesium capable of neutralizing carbon dioxide, thereby reducing the carbon footprint of their products. Miners never recycle their acid, but our technology can regenerate it, so it will play an important role in mining production. If all miners can regenerate most of their acid, it will significantly reduce the carbon footprint of all our daily products," he said.

The company aims to build a large-scale production plant with an annual capacity of 1,000 mt, capable of supplying 1,000 mt of MHP product per year containing 40-45% nickel, with impurity levels that do not affect its processing into battery-grade products.

"We are considering whether it is worthwhile to further produce Class 1 nickel products," Dufresne stated.

Financing

As the critical minerals sector heats up, Dufresne has secured financing from Clean Energy Ventures, a US climate technology investor, BDC Capital, the Quebec provincial government, Mitsui, and other enterprises.

"We see that Quebec and Canada need to produce critical minerals domestically to enhance our ability to produce the minerals needed for future decarbonization and reduce external dependencies. Utilizing mine tailings is a good way to achieve this goal, especially since Quebec is building a battery manufacturing center just 60 kilometers away from us," Dufresne said.