Miners are turning to bacteria and other new ways to filter copper from waste rock

A sheet of copper cathode is photographed in Chile on March 31, 2008. The photo was taken on March 31, 2008. REUTERS/Ivan Alvarado

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May 11 (Reuters) – Driven by rising prices and demand, Rio Tinto Ltd. (RIO.AX), Freeport-McMoRan Inc (FCX.N) and other global miners are deploying a suite of new filtration technologies that can extract low concentrations of copper from waste rock. It helps to avoid lengthy delays in permitting mines.

Copper prices have nearly doubled in the past two years due to the growth of the electric car industry, as demand has prompted miners to find faster ways to produce the metal.

This has led the industry to reconsider the piles of waste rock stored at mine sites around the world, with Rio and other companies estimating that these piles can contain up to 100 million tons of copper.

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In conventional mining, leaching involves applying acid to piles of rock to extract copper, gold, or other minerals. The remaining rocks are stored on site in waste piles.

Now, miners aim to use bacteria or other newly developed chemicals to extract more copper from those leftover rocks in a secondary leaching process. That could enable them to produce copper at concentrations of 0.5% or less – compared to typical mine grades of 0.6% to 1% or more – in an economical way, the companies said.

“It’s the equivalent of bringing in a new mine without incurring all the capital costs,” said Kathleen Quirk, president of Freeport.

These new operations also do not require new regulatory approval, which helps avoid battles with conservationists and others. In Arizona, for example, Rio is facing strong resistance to a proposed precision copper mine.

green and cheaper

While filtration is usually done in lined pits, environmentalists have long worried that acids and other substances could find their way into drinking water supplies. The mining industry said it believes the leaching is safe.

Freeport uses several new leaching technologies that it has developed internally and with partners at its Morenci mine in Arizona – North America’s largest copper mine – estimating that 19 billion pounds of copper is not recoverable by conventional leaching methods.

The miner estimates that new leaching techniques could boost its annual copper production by at least 100 million pounds within a few years, equal to 2.6% of its production last year.

Freeport and BHP Group Ltd (BHP.AX) last year invested in Jetti Resources LLC, a privately owned filtering firm that also considers BlackRock Inc (BLK.N) an investor.

The companies said Getty’s technology helped Capstone Mining Corp (CS.TO) double its copper production at a mine in Arizona last year.

Getty said it was working on a filtration project with another miner, which it declined to say, which will start producing 50,000 tons per year next year. The company charges its customers a royalty fee per pound linked to the price of copper.

“The mining industry is used for projects with high capital budgets that are difficult to allow and have environmental disadvantages,” said Mike Otwin, Getty’s founder and CEO. ‘Our offer to the industry is cheaper.’

‘Quite substantial’

Rio Tinto, which says it has been studying filtration techniques for 30 years, says it has developed bacteria that naturally produce heat when applied to certain types of rock, which helps pull out the copper.

The company struck deals with Lion Copper and Gold Corp. (LEO.V) and Arizona Sonoran Copper Co. (ASCU.TO) to test technology it dubbed “Nuton” in a 17th-century play. British scientist who first developed the theory of gravity.

“Our ambitions here are very big,” said Adam Burley of Rio, who runs Nuton. “In order to get the full scale of the award, financially and socially, we need to spread in and out of the Rio wallet.”

Other than copper, tech companies are looking to boost the use of filtration for other metals, including rare earth elements, a group of 17 metals found in a range of electronics.

Massachusetts-based startup Phoenix Tailings Inc says it has developed technology to filter several types of rare earth minerals, including neodymium used in magnets, from waste rock without using harsh chemicals. Its process is still under lab testing, but it hopes to start commercial operations by the middle of the decade.

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(Reporting by Ernst Scheider) Editing by Margarita Choi

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