May 03, 2019

Rare Earths From Mining Waste

2 minutes

The 17 rare earth elements have become important parts of much of

modern technology. Despite their name,

most of these elements are relatively plentiful in the earth’s crust, but

because of their geochemical properties they are typically dispersed and not

often found concentrated in minerals. As

a result, economically exploitable ore deposits are uncommon. There are no significant sources in the U.S.

Rare earths play important roles in high-performance magnets, electric

motors in vehicles, wind turbines, microphones and speakers, and in portable

electronics like cell phones. As these

applications become ever larger, the need for additional sources of rare earths

increases.

Researchers at Idaho National Laboratory and Rutgers University have

studied a method for extracting rare-earth elements from mining waste that

could greatly increase the world’s supply of these valuable materials.

It turns out that large amounts of rare earths exist in phosphogypsum, a waste product from producing phosphoric acid from phosphate rock. The U.S. alone mined 28 million tons of phosphate rock in 2017. (Phosphoric acid is used in the production of fertilizers and other products).

The researchers estimate that more than a billion tons of

phosphogypsum waste sits in piles at storage sites across the U.S. alone. World-wide, about 100,000 tons of rare earth

elements per year end up in phosphogypsum waste. This compares to the total current world-wide

production of rare earth oxides of 126,000 tons.

The researchers studied methods for extracting the elements from the

waste. A method utilizing a common environmental bacterium showed great

promise.

There are concerns about residual radioactivity and other environmental issues in dealing with the waste material, but the world’s supply of rare earth elements might become much greater based on this research.

**********

Web Links

Critical Materials: Researchers Eye Huge Supply of Rare-Earth Elements from Mining Waste

Photo, posted June 19, 2015, courtesy of David Stanley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

...more