Rare earth elements like yttrium are difficult to extract from the ground, but they're crucial ingredients in flat screens and consumer electronics. Now a group of researchers have discovered massive deposits of these elements in mud on the deep sea floor. They believe we could start mining ocean mud to build more smart phones.
In this map of the Pacific Ocean (click to expand), you can see the sites where the scientists found mud saturated with yttrium and other valuable elements. Their discovery could usher in a rare earth element rush — on the bottom of the ocean.
Geologist Yasuhiro Kato and colleagues took 2,000 deep mud samples from 78 different sites throughout the Pacific Ocean, analyzed them using an X-ray fluorescence spectrometer, and discovered that they were rich in rare earth elements. They used acid leaching — a controversial technique used to mine the metals on dry land — to pull rare earth elements from the mud. Based on the amounts of these elements they found, the researchers argued that the seafloor might be a rich resource for the elements. In a paper published this week in Nature Geoscience, they argue:
We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-ﬁfth of the current annual world consumption of these elements.
They believe the elements are so widely spread across the Pacific because they've been dispersed there over millions of years from two active hydrothermal vents, the East Pacific Rise and Juan de Fuca Ridge. Over time, particles from those vents have drifted on currents, and been metabolized by sea creatures, into the rare earth elements that are so difficult to mine on land without using techniques that many scientists have criticized for destroying wildlife and polluting rivers.
It's unclear how mining deep sea mud would be accomplished. Would undersea robots scoop up massive amounts of mud and bring it to the surface, to be acid leached in processing plants? Would we set up undersea mining cities, or use platforms similar to those for oil drilling? It's easy to imagine these mining operations could be equivalent to clear-cutting 5 square km of the ocean floor every year — or even more, as demand for these elements is only likely to grow. (For more information on all the electronics that depend on rare earth elements, you can read this article from Colorado School of Mines Magazine [PDF].)
What's even more unclear is how deep sea mud mining could be accomplished without destroying the delicate ecosystems at the bottom of the ocean, including corals and other creatures who are critical to the health of sea environments. Look carefully at the map above. You might be seeing a vision of tomorrow's mining industry.
Read the full scientific article via Nature Geoscience