Copper was the first metal discovered and used by human beings in 9000 BC. Ancient humans used the metal for tools, weapons, ornaments and even jewellery.
Today, we use the shiny brown metal widely in building and electrical infrastructure – roughly 20 million tonnes each year. It’s expected that we’ll need much more of it in the coming decades to enable widespread electrification, as a result of the accelerated transition to less carbon-intensive economies.
Copper is a vital element in batteries, electric motors and charging equipment – it’s used four times as much in electric vehicles than their conventional gasoline counterparts. Installations of renewable energy systems are also much more heavily dependent on copper than their fossil-fuel plants – about four to six times more copper per unit of installed power is required. For instance, wind and solar farms, whose copper content is the highest among all renewable energy technologies, require millions of kilograms of copper for each installation.
The element is irreplaceable in these renewable energy systems as it keeps them running at higher efficiencies for a longer working period. But now researchers are actively seeking alternative sources of copper to reduce the load on opencast mines, which contain rocks that hold only 1 % of their mass in copper.
And they have found an unusual place to mine for the element – ancient volcanoes.
Cut out the middleman.
Researchers from Oxford University proposed that instead of mining metal-rich nodules scattered on the ocean floor, which brings technological and regulatory challenges, we could extract the metals from mineral-rich brines generated from deep under ancient volcanoes.
Back in 2015, the research team, led by Professor Jon Blundy, demonstrated how copper-sulphide ores form near volcanoes millions or billions of years ago. In essence, when sulphur-rich gases from the plumbing of active volcanoes rise and encounter metal-rich brine trapped in rocks above pockets of magma, you get copper-sulphide ores.
In a Eureka moment, Dr Blundy suggested: why not leave out the middleman (copper ores), and go straight to the metal-rich brines themselves?
Sucking liquid copper with a long straw.
In a new paper, Professor Blundy confirmed his hypothesis. His team showed that these trapped, subterranean brines are literal ‘goldmines’ with varying concentrations of copper, as well as a slew of other valuable resources such as gold, silver, zinc and lithium.
Their models indicated that the brines potentially hold millions of tonnes of copper, which can be exploited by fluid extraction via deep wells.
The research group highlighted that this new method of extracting resources in solution from wells greatly lowers the cost of mining and ore processing. Furthermore, as intense heat is a significant by-product of this green-mining approach, the cherry on the cake is that this energy could be harnessed to drive operations at the well-head. The amalgamation of benefits vastly reduces the environmental impacts of metal extraction and processing.
Though their finding suggests that copper could be drilled commercially in the same way that oil is, some challenges remain. As such operations are carried out at searing temperatures of more than 400 degrees celsius, they now have to figure out what type of equipment could withstand such conditions, while coming in contact with brines ten times saltier than seawater.
As mining operations are notoriously damaging to the environment, sucking liquid copper out of the Earth’s crust using metal straws 2 kilometres in length might just be the green innovation that the industry needs.
