IEEE Spectrum story about rare earths includes description of the MP Materials mine in the northeastern Mojave Desert, which an executive says of the the seams of brownish and reddish rock, which contain the rare earth ores: “There’s been rare earth mining here since 1952, We think we’ve got at least another 30 years to go.”
CMI conducts research on how to separate the rare earth elements from the other parts in the rock. Of these extractants, CMI Director Tom Lograsso says: “If you can double or triple the separation factor, then you could halve or reduce the number of mixer-settlers by up to two-thirds. If there was a panacea to reduce the costs, the capital costs, the land usage, the water usage, and improve the environmental soundness of the processing, it would be to come up with chemicals that are environmentally safe, and that would also do a better job of separating the rare earths from each other.”
Some of that research is at Oak Ridge National Laboratory, in a CMI project led by Santa Jansone-Popova. She explains that with the conventional process, the solutions become more acidic as they proceed through successive stages of mixer-settlers. Her solution is an extractant that does not operate based on adjustments in acidity: “It operates by a different mechanism, adjustments in ionic strength. That means we can start with a more concentrated acid solution, and then we can recycle that acid solution without adding any chemicals. And when we want to recover those rare earth elements, we’re using a very dilute acidic solution that, too, can be recycled after the precipitation of the rare earths. We can basically recover those rare earth elements with water. There are no additional chemicals added to the system, and all the acid that we’re using in the process can be recycled. That’s the beauty.”
See the full story: Inside an American rare-earth boomtown