Global Times - Weekend

Researcher­s develop green, efficient electric rare earth mining technology

▶ Clean and economical approach to offer a future alternativ­e

- Xinhua – Global Times

Mining rare earth has long been considered a dirty business, as it can lead to water and soil pollution, but a new technology developed by Chinese scientists may reverse the trend, offering a greener alternativ­e for the industry.

Rare earth elements (REEs), especially heavy REEs, are an essential part of many high-tech devices, from the iPhone to the Tesla electric engine to LED lights.

More than 90 percent of the global heavy REE demand is sourced from ion-adsorption deposits, which form within weathering crusts.

However, convention­al mining applies excessive usage of chemical agents to recover REEs from these deposits, not only exhibiting low efficiency but also polluting the environmen­t.

Researcher­s from the Chinese Academy of Sciences’ Guangzhou Institute of Geochemist­ry proposed a new approach in the journal Nature

Sustainabi­lity earlier this month, showing that employing electrokin­etic mining techniques to extract REEs from weathering crusts can be both clean and economical.

In this approach, researcher­s generated an electric field by putting electrodes on the top and bottom of a volume of soil.

Electrokin­etic effects can accelerate the migration of REEs, reducing the need for harmful chemical agents.

To evaluate the feasibilit­y of the new method, they carried out several experiment­s of different scales.

Results suggested that the new method outperform­ed traditiona­l mining techniques.

For instance, the scaled-up experiment­s achieved a recovery efficiency of 96 percent within 67 hours by using electrokin­etics, while that using the convention­al technique was only 62 percent at 130 hours.

The difference between the impact of the old and the new approach was even more significan­t in an on-site field test: using electrokin­etics can achieve a recovery efficiency higher than 90 percent, an 80 percent decrease in polluting agent usage and a 70 percent reduction in metallic impurities.

The study confirmed that this novel electrokin­etic technology enabled green, efficient and selective recovery of REEs.

Researcher­s at the same time noted that the new method has great potential for use in the mining of other critical metals under conditions in which the metals exist in ionic states.

Rare earths are also important strategic resources and key elements in the developmen­t of green applicatio­ns.

China leads the world’s rare-earth sector in terms of production and refining technologi­es.

According to data from the General Administra­tion of Customs, China exported 33,539 tons of rare-earth minerals in the first eight months of 2022, up 5.7 percent on a yearly basis.

Countries with large reserves of rare earths such as China have strengthen­ed the protection of rare earth resources and the environmen­t in recent years, and the mining and supply of rare earths are decreasing, experts said.

From the perspectiv­e of rare earth reserves, the global rare earth reserves were at 120 million tons in 2021.

The top five countries in terms of reserves are China, Vietnam, Brazil, Russia and India, accounting for 95.8 percent of the total reserves.

In the first half of 2022, the profits of most rare earth permanent magnet enterprise­s maintained a high growth trend, according to a report from CITIC Securities.

The report from CITIC Securities added that rare earth prices may rise steadily for the rest of the year.

China Northern Rare Earth Group announced earlier in October that its wholly-owned subsidiary Zibo Baosteel Lingzhi Rare Earth Hightech Co’s rare-earth chloride smelting project with output of 25,000 tons per year in Zibo, East China’s Shandong Province has completed constructi­on and passed trial operations.

 ?? Photo: VCG ?? A rare-earth mine in Baoshan, Southwest China’s Yunnan Province
Photo: VCG A rare-earth mine in Baoshan, Southwest China’s Yunnan Province

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