Researchers find potential new source of rare earth elements

Researchers find potential new source of rare earth elements
Rare earth oxides of gadolinium, praseodymium, cerium, samarium, lanthanum and neodymium. Credit: USDA ARS

Researchers have found a possible new source of rare earth elements—phosphate rock waste—and an environmentally friendly way to get them out, according to a study published in the Journal of Chemical Thermodynamics.

The approach could benefit , according to researchers at Rutgers University-New Brunswick and other members of the Critical Materials Institute, a U.S. Department of Energy effort aimed at bolstering U.S. supply chains for materials important to clean energy.

Rare earth elements like neodymium and dysprosium are essential for technologies such as solar and wind energy and advanced vehicles, along with modern electronics like smartphones. But a shortage of rare earth production in the United States puts our energy security at risk. China produces roughly 90 percent of all such elements.

Recovering them from phosphogypsum—waste from phosphoric acid production—is a potential solution. Each year, an estimated 250 million tons of phosphate rock are mined to produce phosphoric acid for fertilizers. The U.S. mined approximately 28 million metric tons in 2017. Rare earth elements generally amount to less than 0.1 percent in phosphate rock. But worldwide, about 100,000 tons of these elements per year end up in phosphogypsum waste. That's almost as much as the approximately 126,000 tons of rare earth oxides produced worldwide each year.

Researchers find potential new source of rare earth elements
Phosphogypsum, which is watery at first and forms a crust as it dries. Credit: US Environmental Protection Agency

Conventional methods to extract from ores generate millions of tons of toxic and acidic pollutants. But instead of using harsh chemicals to extract the elements, another method might use organic acids produced by bacteria, said Paul J. Antonick and Zhichao Hu, co-lead authors of the study. They are members of the thermodynamics team led by senior author Richard E. Riman, a Distinguished Professor in the Department of Materials Science and Engineering in Rutgers' School of Engineering.

The research team explored using mineral and , including a bio-acid mixture, to extract six rare earth elements (yttrium, cerium, neodymium, samarium, europium and ytterbium) from synthetic phosphogypsum. Scientists led by David Reed at Idaho National Laboratory produced the bio-acid mixture—consisting primarily of gluconic acid, found naturally in fruits and honey—by growing the bacteria Gluconobacter oxydans on glucose. The results suggest that the bio-acid did a better job extracting rare earth elements than pure gluconic acid at the same pH (2.1), or degree of acidity. The mineral acids (sulfuric and phosphoric) failed to extract any rare earth elements in that scenario. When the four acids were tested at the same concentration, only sulfuric acid was more effective than the bio-acid.

A next step would be to test bio-acid on industrial phosphogypsum and other wastes generated during phosphoric acid production that also contain rare earth elements. For their initial study, the researchers evaluated phosphogypsum made in the lab, so they could easily control its composition. Industrial samples are more complex.


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More information: Paul J. Antonick et al, Bio- and mineral acid leaching of rare earth elements from synthetic phosphogypsum, The Journal of Chemical Thermodynamics (2018). DOI: 10.1016/j.jct.2018.12.034
Provided by Rutgers University
Citation: Researchers find potential new source of rare earth elements (2019, March 4) retrieved 25 June 2019 from https://phys.org/news/2019-03-potential-source-rare-earth-elements.html
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Mar 04, 2019
But if it costs 2$ a kilo more or requires significant investment it wouldn't be fair on the poor old mining and mineral futures investors.
Their right to screw up the planet must be protected!

Mar 04, 2019
Meh. Bring the rare earth elements and make money. This sounds like a boondoggle.

Mar 04, 2019
This would be another way to limit China's power, since China produces the lion's share of rare earths (105,000 MT) and, until now, the USA produces nothing. We have become self-reliant in steel and fossil fuels. The more self-reliant, the more impervious to outside pressures; e.g., OPEC.

Mar 05, 2019
Yes, ''National Security" might just be what it takes to make this happen against the tide of market forces. Import Tariffs might be involved.
Oh No did I just agree with Trump: Rate me a 1 immediately.

Mar 05, 2019
Okay boys settle down. Let me give you a quick version of American Trade Practices. Foreigners sell us quality foods, cars, video-game controllers, a huge percentage of the World's industrial production.

& in exchange we pay them with worthless paper we call "Dollars" & you all think this long-time swindle is a bad thing?
So? Whose side are you on?

Sure, we ship most of the World's weaponry but it crappy, obsolete junk for local military & police to use on unarmed peasants. Gotta keep'm in their place. Who then would work the fields to supply America's voracious appetite for drugs?

Don't tell me you boys are on the side of some commie school teacher or PH nurse trying to better their student's lives.
How unAmerican of you!

& every useless toy or braindead TV we import? Is that much less material resource for China's military.

You boys need to pull your noses out of your asses. Actually look at the World & see how we Yanks prosper at everybody else's expense.

Mar 05, 2019
This makes me wonder if there's anything worth having in those giant piles of fly ash sitting by coal plants. They're certainly full of other metals.

Mar 05, 2019
There won't be if they let it all leach into the groundwater.

Mar 06, 2019
Another untapped source are orbiting nickel-iron asteroids & rubble. Not for the N-I which has little intrinsic value aside from the Potassium varieties & the Rare Earths contained within them.

These infalling rocks have been the source for the Pk & R_Es in the Earth's crust since the original elementals got dragged into the Earth's core.

Potassium is a crucial base element for Earth Life. If by some good-fairy miracle, biology can survive, reproduce & thrive off Earth?

It will be this orbiting supply of Potassium with Carbon, Water, Nitrogen & Calcium that will make a sustained colonization effort possible.

The enormous investment it will take to process Nickel-Iron is a losing proposition. It will take some efficient, cost-effective
way to separate the Pk & Rare-Earths from the valueless Nickel-Iron to produce a decent ROI..

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