Uncut diamonds from southern Africa and Canada are seen at De Beers headquarters in London

Johannesburg - De Beers, the world’s biggest diamond producer by value, says it could operate a carbon-neutral mine within half a decade.

The Anglo American unit plans to store carbon-dioxide in kimberlite rock -- a type of ore best known for containing diamonds, but which also naturally reacts with carbon to remove it from the atmosphere. By accelerating that process and using readily-available waste rock, De Beers could offset the emissions from its mines, according to Evelyn Mervine, who’s leading the research project for the company.

While mineral carbonation isn’t a new idea, kimberlite offers ideal properties for storing very large volumes of carbon, Mervine said. De Beers has vast amounts of previously mined waste rock stored in so-called tailings dams above ground at its mines. Depending on how the research progresses, De Beers could eventually offset more emissions than it produces, she said.

“There will be key learnings from this that can be used in larger bodies of rock that can be found throughout the world,” she said.

De Beers is looking at removing carbon dioxide from power generators at its mines by piping the gas through a fluid that can then be injected into the kimberlite waste rock and stored safely, Mervine said. It’s also studying the potential to spread waste rock more thinly to increase carbon extraction from the atmosphere.

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Carbon capture and storage is seen as key to tackling climate change, by removing pollution from the atmosphere that would otherwise be spewed out by power generators and industry. Yet progress in developing the technology has been slow and expensive.

De Beers estimates it could achieve carbon-neutral status at some operations within five to 10 years and is already studying the possibilities at its Venetia mine in South Africa and Gahcho Kue in Canada. The potential for storage at historic tailings at Debswana in Botswana will also be assessed, Mervine said.