Potential CO2 neutral nickel mine in BC
Turnagain tailings could absorb more CO2 than mine emits Metal Tech News – June 2, 2021
Last updated 6/1/2021 at 3:21pm
A mine that produced the nickel and cobalt needed for the lithium-ion batteries powering zero-emission electric vehicles and offering the added benefit of locking up carbon dioxide in rocks for geological time periods would be considered an optimum solution in the battle against global warming. Recent tests carried out at the University of British Columbia indicate the potential that Giga Metals Corp.'s Turnagain project in Northern BC could be one such greenhouse gas-absorbing mine.
"This is exciting news," said Giga Metals President Martin Vydra. "We now have empirical data that supports our ambition to build the world's first true carbon-neutral nickel mine, meaning a project that achieves carbon neutrality without purchasing carbon credits."
A preliminary economic assessment completed last October outlined plans for a mine at Turnagain that would produce an average of 33,215 metric tons of nickel and 1,962 metric tons of cobalt annually over a 37-year mine life.
It just so happens that the tailings left behind after the nickel and cobalt extracted from the ore at Turnagain are really good at absorbing carbon dioxide out of the atmosphere. This process turns the tailings, which are typically crushed to a sand- or silt-like consistency, into carbonate rock.
A team led by University of British Columbia Professor Greg Dipple, who has been studying mineral sequestration of CO2 in mine tailings around the world for more than 15 years, shows the potential for this mineral carbonation process to permanently sequester vast amounts of CO2 at Turnagain.
Dipple said an initial four-week test of Turnagain material showed average absorption rates of 2.7 kilograms of CO2 per square meter per year.
At this rate, Giga calculates that a mine at Turnagain could absorb roughly 900,000 metric tons of CO2 over the life of the operation, or 0.72 metric tons of CO2 per metric ton of nickel produced.
Considering that this operation is only estimated to emit 0.75 metric tons of CO2 per metric ton of nickel with an electric haulage fleet, this baseline absorption would nearly make the mine carbon-neutral without any optimizations.
Dipple's testing, however, indicates that the CO2 absorption rates would increase under actual mining scenarios.
"A second sample was tested with periodic mixing of the tailings layer, reflecting potential active management of a tailings facility; this second sample showed a sustained increase in carbon sequestration rates of 25%," he said. "During periods of optimal moisture and mixing, the sequestration rates increased up to three times the long-term average."
The testing also showed that only about 10% of the brucite – a magnesium hydroxide mineral at Turnagain responsible for sponging atmospheric CO2 – was consumed during the one-month sequestration test, indicating that Turnagain mine tailings would absorb more of the greenhouse gas with longer exposure to the air.
While much more detailed and longer-term testing will need to be done, a mine at Turnagain with an electrified mining fleet powered by the hydroelectric Northern BC is known for has the potential to be a CO2-negative producer of nickel and cobalt.
The ability to produce these lithium-ion battery metals with zero or less CO2 emissions would likely be attractive to EV and battery manufacturers looking to improve the environmental, social, and governance profiles of their supply chains.
"We recognize the growing importance of strong ESG performance from commodity producers," said Vydra. "We are proud that our project is at the forefront of being able to contribute to a carbon-free industry. We are also looking forward to continuing work with Dr. Dipple as we see a potential for Turnagain to actually generate carbon credits under the right scenario, however there is still significant work ahead before we can address this potential."
Dipple and his team are excited to get that work started.
"We look forward to working with Giga Metals to conduct additional tests on larger samples," he said.