America's Sedimentary Phosphate Deposits may be key to Global Rare Earth Element Crisis

Rare Earth Elements in Sedimentary Phosphate Deposits: Solution to the Global REE Crisis?

Authors:

Emsbo et al

Abstract:

The critical role of rare earth elements (REE), particularly heavy REE (HREE), in high-tech industries has created a surge in demand that is quickly outstripping known global supply and has triggered a worldwide scramble to discover new sources. The chemical analysis of 23 sedimentary phosphate deposits (phosphorites) in the United States demonstrates that they are significantly enriched in REE. Leaching experiments using dilute H2SO4 and HCl, extracted nearly 100% of their total REE content and show that the extraction of REE from phosphorites is not subject to the many technological and environmental challenges that vex the exploitation of many identified REE deposits. Our data suggest that phosphate rock currently mined in the United States has the potential to produce a significant proportion of world’s REE demand as a byproduct. Importantly, the size and concentration of HREE in some unmined phosphorites dwarf the world’s richest REE deposits. Secular variation in phosphate REE contents identifies geologic time periods favorable for the formation of currently unrecognized high-REE phosphates. The extraordinary endowment, combined with the ease of REE extraction, indicates such phosphorites might be considered as a primary source of REE with the potential to resolve the global REE (particularly for HREE) supply shortage.