US Effort to Extract Rare Earths from Fly Ash

US Effort to Extract Rare Earths from Fly Ash

According to reports, researchers from the Georgia Institute of Technology have invented a concise process in the US. They could extract rare earths from fly ash without producing toxic substances with ionic liquids. In the paper published in Environmental Science & Technology, scientists explained that ionic liquids are environmentally friendly and reusable. In particular, betainium bisimide can selectively dissolve rare earth oxides but not other metal oxides.

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a new source of rare earths image

Scientists claim that heated ionic liquids would be dissolved in water, and could become two-phase when cooled. Based on this, they tested whether they could selectively separate target elements from fly ash and whether they can effectively clean. So that the scientists could develop a safe and environment-friendly craft.

For that, the research team pretreated and dried the fly ash with an alkaline solution. Then, the ash is heated to form a single phase in the same water. After cooling, the solution is successfully separated.

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The plan to turn coal country into a rare earth powerhouse image

Ionic liquids would extract more than 70% of rare earth elements from fresh fly ash, and the extraction rate of weathered the ash that has been stacked in tailings ponds for many years is even higher (97%). The last step is to extract rare earth elements from the ionic liquid with dilute acid. Researchers found that adding betaine in the leaching process is a benefit for increasing the extraction rate of rare earth elements.

The rare earth elements that could be recovered, such as scandium, yttrium, lanthanum, cerium, neodymium, and dysprosium.

In the end, the team also experimented with the reusability of ionic liquids. This team found that the extraction efficiency did not change, after removing excess acid with cold water, and three rounds of leaching and cleaning.

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Researchers extracting rare earths from coal waste image

"This low-emission method could produce solutions that are rich in rare earths and limited impurities, and could also be used to recover precious metals from the same ash in tailings ponds," the scientists said at a media conference. This method is critical for coal-producing areas in the US, such as Wyoming. In the current declining demand for fossil fuels, they are seeking to reinvest in local industries.

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