Yttrium. Praseodymium. Dysprosium. These are some of the elements known collectively as rare earth metals, and while you may have never heard of them (or may not be able to pronounce their names) you likely encounter them every day. Pull out your smartphone.
There they are, embedded in the screen, the circuitry and the speakers. With millions of smartphones and countless other electronics built every year using rare earth metals, supplies of these high-tech materials may someday become scarce. A new study shows, however, that an untapped source of rare earth elements may lie under the sea.
The potential deep-sea sources of rare earth elements are nodules of iron and manganese that are abundant on the ocean floor. These nodules, called ferromanganese deposits, build slowly over time as dissolved iron and manganese in seawater attaches to seafloor sediments. Many other metals hitch a ride and become incorporated into the deposits, but in much smaller quantities than iron or manganese. Those include metals such as cobalt and nickel, as well as rare earth metals.
Geochemists in Germany developed a method to efficiently extract rare earth metals from ferromanganese nodules using the solvent desferrioxamine-B, also known by its commercial name, Desferal, a treatment for the iron-intoxication disease hematochromatosis.
Desferal binds more strongly to some metals than others and when applied to ferromanganese nodules, effectively and efficiently extracts rare earth metals, leaving other metals behind in the nodules. By refining their ore-leaching method, the team was able to extract up to 80 percent of four rare earth metals from some ferromanganese nodules.
Their results are published in Applied Geochemistry.
With around 130,000 metric tons of rare earth metals mined each year, and 95 percent of those mined in one country (China), the value of an alternative, efficient source of high-tech metals is clear. And as demand increases, these deep-sea rocks could become components in future solar panels, wind turbines and, of course, smartphones.