University of Texas scientists develop CO2-injection tech that breaks rocks and stores carbon.

University of Texas at Austin researchers may have made a literal groundbreaking discovery for mining the nickel and cobalt needed for electric vehicle batteries – storing more carbon dioxide than is needed to produce these lithium-ion battery metals while also using the CO2 as a rock conditioner that makes the mining and processing less energy intensive.

Many nickel-cobalt deposits are hosted in ultramafic rocks, a type of igneous rock that also contains minerals that are really good at capturing CO2 and turning it into carbonate rock. While ultramafic rocks represent some of the largest CO2-capturing reservoirs on Earth, their potential is limited due to often being buried and poor permeability that limits the amount of CO2 that can be absorbed.

A team led by Estibalitz Ukar, a research scientist at the Bureau of Economic Geology at the University of Texas Jackson School of Geosciences, has developed a technique to overcome this limitation that involves injecting a solution of water and CO2 into ultramafic rock containing nickel and cobalt. The CO2 in this effervescent solution transforms into a softer carbonate rock that can be stored at the geological timescale.

"Mining processes create a lot of CO2 as a byproduct. If you can capture what is produced at the mine, then you can come up with a low-emission operation," said Ukar.

The process of carbon latching onto other minerals to form carbonates also fractures the hard igneous host rock.

Mining companies could use this technology to lower the energy and costs related to digging up and crushing the rock in order to free the nickel, cobalt, and other valuable minerals.

The holy grail of the quest led by Ukar is to quickly develop a market-ready technology that offers a way to store more CO2 than is expended while mining critical battery metals in North America.

"If you are able to capture and store all the CO2 produced during the mining operations, that makes it carbon neutral. We want to go beyond that and capture even more carbon, making the operation carbon negative," said the University of Texas scientist.

Miner urgency

Ukar's quest for a CO2-negative nickel-cobalt mine is being supported by a $5 million grant from the U.S. Department of Energy's Mining Innovations for Negative Emissions Resource Recovery (Miner) program.

The three-year project will work to refine the mining method in the lab for two years before advancing to a full-scale field test in partnership with Canada Nickel Company, which is focused on producing zero-carbon nickel, cobalt, and other metals.

Ukar said the work with Canada Nickel will be carried out at one of 20 newly discovered ultramafic bodies near the U.S.-Canada border that are forecast to be an important new source of critical minerals.

First, however, the University of Texas team is spending about two years perfecting the CO2 storage process in the lab.

"We particularly want to work on finding ways to make the reaction that stores CO2 in ultramafic rock faster," said Ukar. "Instead of geologic timescales, we need to make the reactions occur within weeks to months for the process to be economically viable for mining."

While the idea of injecting CO2 into ultramafic rocks to store the carbon and make mining easier is new, the underlying concept being explored by the University of Texas team is not.

Iceland-based Carbfix has developed and successfully implemented its own approach to permanently storing CO2 as a carbonate mineral. However, there are two major differences between that technology and what the Ukar-led team is developing – Carbfix stores CO2 in basalt, an igneous rock similar to ultramafic, and the Icelandic company's tech was not developed with mining in mind.

Carbfix

This drill core shows white carbonate crystals formed from CO2 injected at a Carbfix site in Iceland. University of Texas scientists are working to utilize this process to both store carbon and fracture ultramafic rocks enriched with nickel, cobalt, and other metals.

While the rocks are different, the methods are similar, and Sandra Ósk Snæbjörnsdóttir, who is the head of CO2 mineral storage for Carbfix, is collaborating with the University of Texas team on its project.

Read DOE funds carbon antimining at Tamarack for another example of Carbfix working with others to adapt its CO2 injecting technology to mining nickel in the U.S.

Ukar feels a sense of urgency to advance the CO2 injecting technology being developed under the Miner program out of the lab and onto field tests and commercial mining operations.

"The demand is high now, but we will see a huge increase in the next three to five years as we transition into lower-emission technologies, such as electric vehicles," she said. "We need to meet the demand by finding creative ways to reduce costs and emissions, find new sources of metals, and make the mines of the future more sustainable. And we need to do it fast."