TOKYO -- Mud rich in rare-earth metals in the seabed near an isolated Japanese coral atoll is widely distributed and not as deep as initially thought, researchers have discovered, increasing the possibility of commercial mining.
Rare earths include dysprosium, a material for powerful magnets used in motors of hybrid vehicles, and yttrium, used to build lasers.
University of Tokyo professor Yasuhiro Kato had found in 2012 high concentrations of rare earths in mud sampled from beneath the ocean floor near Minami-Torishima, roughly 1,900km southeast of Tokyo. And in a study last year by the university and the Japan Agency for Marine-Earth Science and Technology, or Jamstec, researchers had discovered that the concentration exceeds 5,000 parts per million -- more than 30 times that of major Chinese mines.
This time, Kato and researchers from Jamstec and elsewhere studied the seabed about 250km south of the island in Japan's exclusive economic zone from mid- to late October. Mud containing high concentrations of rare earths was found widely distributed just 2 to 4 meters under the seabed. This makes extraction easier than if the mud were more than 10 meters down as initially believed.
The researchers plan to closely look at other areas next spring and after, in addition to conducting a feasibility study for mining. "The amount [of rare earths] used in Japan in a year can be secured in a single square kilometer of these waters," Kato said.
Researchers from the University of Tokyo and the Tokyo Institute of Technology joined with Mitsui Mining and Smelting, offshore drilling rig operator Modec, rare-earth-alloy maker Santoku and others this month to form a consortium to promote exploitation of resources from seabed mud. The group aims to develop mining and refining technologies necessary for commercial production of rare earths from mud pumped up from 5,600 meters to 5,800 meters beneath the surface of the ocean.
Export restrictions by China, which accounts for more than 90% of global output, have made rare-earth prices spike and destabilized supplies. This has prompted the Japanese government to negotiate with other countries to procure rare earths, but the Chinese continue to dominate. Japanese companies have cut back on use and stepped up recycling to get by.
Last year, the government positioned mining rare-earth metals from the seabed as a goal of its ocean policy. But developing ocean-floor resources at depths beyond 5,000 meters is unprecedented.
Many scientists believe that applying existing technologies would make mining possible. The consortium is examining a variety of technologies, including pumping air into the seabed to draw up the mud.
But rare-earth prices have fallen considerably from the peak, so deep-sea mining may not be economically feasible unless the costs can be cut.