Purdue University researchers have found an efficient and inexpensive way to extract rare earth elements (REE).
The new chromatography separation technique could enable the U.S. to enter into the $4 billion rare earth element production market while recycling coal ash in an environmentally friendly way.
According to the researchers, the value of the products that require rare earth metals is valued at more than $4 trillion per year. REEs used in the U.S. are primarily imported from China, which controls over 90 percent of the supply.
“REEs have many important applications in things such as permanent magnets in power generation and electric cars, batteries, petroleum refining catalysts, phosphors in color televisions, and many electronics including cellphones. The demand for REEs is predicted to grow dramatically over the next several decades,” said Linda Wang, inventor of the technology and Purdue’s Maxine Spencer Nichols Professor of Chemical Engineering.
“Separating rare earth elements is extremely difficult because the elements have the same ionic charge and are similar in size. Current separation technologies produce large amounts of chemical waste, which cannot be economically recycled,” she said. “One of the 10 most polluted sites in the world is a manmade lake in China, where the waste effluents from REE extractions are stored.”
Wang has developed new chromatography separation techniques that could separate rare earth elements first from other impurities and then from each other by using only a few chromatography units.
The processes involve ligand-assisted elution or displacement chromatography methods using robust, low-cost, inorganic sorbent titania or polymeric sorbents.
Wang says that they are the first group in the world to develop this technology. Additionally, the byproducts of their process include silica gel, aluminum oxide, and other metal oxides of commercial value, making the overall process profitable and economical.
Image, video and content: Purdue University