A rare earths recovery breakthrough straight from the corn field…

United States – A new biochemical leaching process to recover valuable rare earth metals from discarded electronics has been developed by a research team at Ames Laboratory in the US state of Iowa. And the key ingredient is somewhat unusual: corn.

Chances are you have never heard of Gluconobacter – a strain of bacteria that produces acid. In combination with corn leaves and stalks left over from the harvest, this presents an innovative ‘biological mining’ solution, according to researchers at the laboratory’s Critical Materials Institute (CMI).

The bacteria are ‘hungry little things’ that ‘thrive in a sugar-rich environment’, notes David Reed, the principal investigator for the research project. The team found that exposing the bacteria to the natural sugars in corn leaves and corn stalks enabled them to dissolve and extract the rare earth metals from waste materials.

Essentially, the metals were stripped to their base elemental state.

The ‘biological mining’ approach is described as cost-competitive for larger-scale commercialisation. It could also provide a business boost for Iowa’s farmers, Reed observes.