How bacteria play a role in sorting critical minerals

Apr 22, 2023

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The Big Story

Future smartphones and electric vehicles could run on metals sorted by bacteria — which could help the future of mining look more like recycling.

Certain bacterial proteins take different forms depending on the element they bind to, according to a newly published study in Nature.

That creates an easy way to distinguish between different metals — in particular, two critical metals that are otherwise very difficult to tell apart.

Rare-earth minerals aren't actually rare — they’re scattered across the earth in low quantities and often come mixed with other rocks.

Rare earths are the 15 elements on the periodic table between 57 and 71 whose unique chemical properties give them a bewildering array of technical applications.

Often minerals of very different value are mixed together, such as neodymium and dysprosium, both of which are powerful magnets used in electric devices. Dysprosium, which is more expensive, is essential for nuclear fuel rods.

Separating them is the problem. Because rare earths are so chemically similar, the typical tricks for refining metals out of crushed rock — like using solvents that dissolve one metal but not another — don't easily work when attempting to pull them apart.

"But you run into a second problem once they are out, because you need to separate multiple rare earths from one another. This is the biggest and most interesting challenge, discriminating between the individual rare earths, because they are so alike," lead author Joseph Cotruvo of Penn State said in a statement.

Methods for doing so produce an enormous amount of pollution. A "simple method" promoted by one chemical company requires dissolving the dysprosium in benzene, a common industrial chemical that is also a powerful cancer-causing chemical.

That's where the microbial sorters come in.

"Biology manages to differentiate rare earths from all the other metals out there — and now, we can see how it even differentiates between the rare earths it finds useful and the ones it doesn't," Cotruvo said.

They are incredibly sensitive, he noted.

"This protein has the ability to differentiate at a scale that is unimaginable to most of us — a few trillionths of a meter, a difference that is less than a tenth of the diameter of an atom."

The team didn't apply itself to the most energy-intensive parts of mining — breaking apart rock to reveal the mineral-rich ores within, which then must be further crushed as part of processing.

But Cotruvo argued that better sorting methods could help humans access a rich store of future minerals: the trace amounts of rare earths left behind in tech waste.

"If you can harvest rare earths from devices that we already have, then we may not be so reliant on mining it in the first place," Cotruvo said.

Welcome to The Hill's Sustainability newsletter, I’m Saul Elbein — every week we follow the latest moves in the growing battle over sustainability in the U.S. and around the world.

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Hold Up

A group of 150 grassroots nonprofits from across the country is calling on President Biden to halt the construction of new pipelines transporting carbon dioxide.

Getting up to speed: Earlier this week, congressional leaders struck a deal to raise the national debt ceiling — keeping the government open — in exchange for sweeping reforms to the national permitting process, as The Hill reported.

In plain language: These changes seek to make it easier for corporations to permit — and harder for activist groups to fight — new infrastructure. Activist groups argue that sweeping new federal environmental rules make that a clear and pressing issue.

New rules: Earlier this month, the Environmental Protection Agency (EPA) instituted regulations requiring all coal plants and some gas plants to capture and store their carbon emissions, The Hill reported.

Public deceit: "Pipelines to transport CO2 are the key component of the carbon capture scam," Jim Walsh, policy director of the group Food & Water Watch, said in a statement.

Fossil fuel companies have used "lies and misinformation to convince the public and policy makers that these dangerous and expensive projects are something other than a money maker for dirty energy producers," Walsh added.

Putting the pieces together: The new EPA rule implies a sweeping buildout in pipelines to move carbon dioxide from places that produce it — as a byproduct in making chemicals or electricity — to places with the right geography to store it.

Near miss: The textbook version of such a leak happened in 2020 in Satartia, Miss., where a broken pipeline that released asphyxiating fumes sent 45 to the hospital, though no one was killed, according to The Des Moines Register.

Removing a human obstacle: Without permitting reform, this buildout will be difficult to accomplish, at least in the critical crossroads of the Midwest.

As it happens: In that area, well-organized networks of farmers and environmentalists are now mobilizing against two large pipeline networks proposed to transfer carbon dioxide from Iowa biodiesel plants to be used to help produce oil in North Dakota.

But permitting reform would allow corporations wide latitude to seize land for pipelines whether landowners want them to or not.

Too much, too fast: On Tuesday, the coalition of groups argued that this proposed buildout is happening too far in advance of potential safety regulations.

Meanwhile, the grassroots group wrote in a letter, the federal government is already receiving permit requests for new carbon dioxide pipelines.

"The dangers will be compounded if [the government] permits these pipelines before PHMSA has completed its rule," they wrote.

Second front: The Bold Alliance, a group that grew out of the resistance to the Keystone XL, has also called on Transportation Secretary Pete Buttigieg — who oversees PHMSA — to not approve any carbon dioxide pipelines before the agency makes safety rules.

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