Chromatography techniques yield rare earth elements from coal ash

Rare earth elements (REE) consist largely of Lanthanides (Lns) - a series of 15 metallic elements – and the value of products requiring them is estimated at over $4 trillion per year.

“REEs have many important applications in things such as permanent magnets in power generation and electric cars, batteries, petroleum refining catalysts, phosphors in colour televisions, and many electronics including cellphones,” said Linda Wang, inventor of the technology at Purdue University, Indiana. “The demand for REEs is predicted to grow dramatically over the next several decades.”

Separating rare earth elements is, however, extremely difficult because the elements have the same ionic charge and are similar in size, said Wang. They also occur in ores in concentrations of a few thousand parts per million.

“Extensive processes of mining, grinding, extraction, and purification are needed to transform the ores to very high purity [approximately 99.9 percent minimum] rare earth metals required for commercial applications,” she said. “Typically, old technologies from the 1950s are used for separation and purification. They usually require 1,800 different extraction stages in series and in parallel for purification.”