Miners turn to bacteria and other new ways to leach copper from waste rock

Lion Copper and Gold

11/05/2022 16:51

By Ernest Scheyder
    May 11 (Reuters) - Rio Tinto Ltd  RIO.AX , Freeport-McMoRan
Inc  FCX.N  and other global miners, spurred by rising prices
and demand, are deploying a raft of new leaching technologies
that can extract low concentrations of copper from waste rock
and help avoid lengthy mine permitting delays. 
    Copper prices  CMCUc1  have nearly doubled in the past two
years largely due to the electric vehicle industry's growth,
with the demand prompting miners to find faster ways to produce
the metal. 
    That has led the industry to reconsider piles of waste rock
stored at their mine sites across the globe, with Rio and other
companies estimating these piles could contain as much as 100
million tonnes of copper.
    In conventional mining, leaching involves applying acid to
piles of rock in order to extract copper, gold or other metals.
The remaining rock is stored on site in waste piles. 
    Now, miners aim to use bacteria or other newly developed
chemicals to extract even more copper from that waste rock in a
secondary leaching process. That could enable them to produce
copper at concentrations of 0.5% or lower - compared with
typical grades in mines of 0.6% to 1% or beyond - in an economic
way, the companies said. 
    "It's the equivalent of bringing on a new mine without
having all the capital costs," said Freeport President Kathleen
Quirk.
    These new processes also do not require fresh regulatory
approval, helping to avoid fights with conservationists and
others. In Arizona, for instance, Rio faces strong resistance to
its proposed Resolution Copper mine.
    
    GREENER AND CHEAPER
    While leaching is typically done on lined pits,
environmentalists have long worried acids and other materials
can find their way into drinking water supplies. The mining
industry has said it believes leaching is safe.  
    Freeport is using several new leaching technologies it
developed internally and with partners at its Morenci mine in
Arizona - North America's largest copper mine - where it
estimates 19 billion pounds of copper are unrecoverable by
traditional leaching methods. 
    The miner estimates that new leaching technologies could
boosts its annual copper production by at least 100 million
pounds within a few years, equivalent to roughly 2.6% of its
output last year.
    Freeport and BHP Group Ltd  BHP.AX  invested last year in
Jetti Resources LLC, a privately-held leaching firm that also
counts BlackRock Inc  BLK.N  as an investor.
    Jetti's technology helped Capstone Mining Corp  CS.TO 
double its copper production at an Arizona mine last year, the
companies said. 
    Jetti said it is working on a leach project with another
miner it declined to identify that it says will open next year
with 50,000 tonnes of annual production. The company charges its
customers a per-pound royalty that is linked to the copper
price. 
    "The mining industry is used to high capital budget projects
that are hard to permit and have environmental drawbacks," said
Jetti founder and Chief Executive Mike Outwin. "Our proposition
to the industry is cheaper."
    
    'QUITE SUBSTANTIAL' 
    Rio Tinto, which says it has been studying leaching
technologies for 30 years, says it has developed a bacteria that
naturally produces heat when applied to certain types of rock,
helping to pull out the copper. 
    The company has inked deals with Lion Copper and Gold Corp
 LEO.V  and Arizona Sonoran Copper Co  ASCU.TO  to test out the
technology, which it has labeled "Nuton" in a play on the name
of the 17th-Century British scientist who first developed the
theory of gravity.  
    "Our ambitions here are quite substantial," said Rio's Adam
Burley, who runs the Nuton program. "In order to capture the
full size of the prize, both financially and socially, we need
to deploy within and beyond Rio's portfolio."    
    Beyond copper, technology firms are looking to boost the use
of leaching for other minerals, including rare earths, a
grouping of 17 metals found in a range of electronics.
    Massachusetts-based startup Phoenix Tailings Inc says it has
developed technology to leach several types of rare earth
metals, including neodymium used in magnets, from waste rock
without using harsh chemicals. Its process is still in lab
testing, but it hopes to begin commercial operations by
mid-decade.

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In Arizona, Rio Tinto CEO seeks 'win-win' for Resolution copper
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 (Reporting by Ernest Scheyder
Editing by Marguerita Choy)
 ((ernest.scheyder@thomsonreuters.com; Twitter: @ErnestScheyder;
+1-713-210-8512; Reuters Messaging:
ernest.scheyder.thomsonreuters.com@reuters.net))