Nickel West in Australia is one of many mines that could use microwaves to store CO2 in waste stones
BHP
Mining generates billions of tons of waste rock every year. If these piles of unused stone are available to respond with carbon dioxide, they can help remove great love to the greenhouse gas from the atmosphere. However, the current methods that burn fossil require fuel to cook the rocks at high temple. A boot of carbon removal has now found microwaves that such cliffs could cause them to respond with CO2 using less energy.
“It’s like microwave popcorn,” says Sean Lowrie at Arca in Canada, who develops the technology. Intoread of heating the whole rock, the microwaves heat only certain molecules – not contrary to how a kitchen microwave is popping maize by heating the water inside a core.
A growing number of companies use rocks to remove CO2 from the atmosphere to offset emissions from burning fossil fuels. Some of these improved rocky weather projects scattered crushed volcanic rock on farms where it is minerals CO2 when dissolved; Others inject CO2 into similar cliffs underground. A number of companies, including Arca, aim to use my tailings that are left from extracting metals like nickel and chrome.
These metals often occur in Malme full of serpentine minerals, which are rich in magnesium that responds with CO2. According to an analysis from Arca, there are currently about 28 billion tonnes such tailings around the world, with 3 billion more tonnes produced each year. They estimate that existing tailings could store up to 8.7 billion tonnes of CO2, equivalent to about two years of value of US emissions.
But these Serpentine cuts do not respond quickly at normal press and temperature on the surface. Heating the cliffs to high temperatures makes them more reactive, speeding up their ability to quickly mineralize CO2. But it usually requires burning fossil fuels to generate the heat.
Using microwaves to warm the cliff instead could offer a few benefits, says Peter Scheuermann at Arca. Instead of burning fuels to generate heat, the process could be powered by pure electricity and use less energy than direct treatment of the rocks with heat. Nor would it take so long to treat the rocks. This means that it can be easy for mining companies to add a microwave step when treating tailings, although it could also act as an independent system, he says.
According to a patent filing from the company, Scheurmann and his colleagues at Arca found that Zapping -Serpentine with microwaves for several minutes improved its reactivity to CO2, causing the chemical change at a lower temperature and used less energy than thermal treatments.
“By giving the rock energy, you break bonds within its structure and release magnesium” to respond with CO2, says Scheuermann. They also show that the treated serpentine responds with CO2 much more than untreated rock that mineralizes the gas faster.
“The improvement they show here looks very dramatatic,” says Rafael Santos at the University of Guelph, Canada, who undergoes patent archiving. However, he says it is difficult to tell from the document alone how much serpentine is treated by the microwaves and how these results would translate into a realistic setting.
Scheurmann did not offer more specific figures about how much they expect the microwave treatment to change the amount of CO2 that could be caught with serpentine, but to say “It’s a drastic increase. It is an order of size boost in both speed and capacity”.
The company has only tested the procedure in the laboratory and has not yet delivered any of the nearly 700 tonnes of CO2 removal it has been sold so far. But Scheurmann says a scaled version would involve the feeding of rocks through a fall or on a conveyor belt where they would pass through a microwave field before being deposited at a tailoring site. The company has also developed an autonomous rover that can itch tailings to maximize the exhibition to the air. Once the reaction is completed, a new layer of tailings would be laid.
“With this pre -treatment with microwaves, you unlock much more potential for CO2 storage,” says Quin Miller at Pacific Northwest National Laboratory in Washington State. “It’s exciting.” He says the treatment could also help extract more nickel, an important metal in batteries, from the rock.
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