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Rare earth elements are key components in our electrified world, used in everything from electric motors to flat-screen televisions. But acquiring them is a messy business.
Rare earths aren’t rare in the Earth’s crust, but they’re hard to come by: much of it is stuck in clay and a lot of area has to be dug up to collect relatively small amounts.
The collecting is done by pumping chemical leaching agents, such as ammonium nitrate, through the clay deposits. The agents scour rare earths off the clay and carry it down to bedrock, where it’s collected.
Those chemicals pollute water and poison soils. A lot of the world’s supply of rare earths come from China and Myanmar, both of which are casual at best about environmental protection.
At the Chinese Academy of Sciences, a research group tried a cleaner approach.
The team placed electrodes at the top and bottom of a field of soil and shot an electric current through it.
The current-enhanced method collected more rare earths faster while using smaller amounts of leachates and could cut mining costs by two-thirds, according to the scientists’ calculations.
The researchers are trying their technique on a 2,000-ton field to learn how best to scale their discovery to practical use.
TRENDPOST: The new method could ease some opposition to rare earth extraction that keeps the U.S. and other countries from developing their own deposits.
Because the demand for these elements will continue to grow, researchers will persist in looking for cleaner ways to collect them or for substitutes, as we reported in “Scientists Synthesize Alternative to Rare Earth Metals” (1 Nov 2022).