The Nikkei reports that in 2024, Japan will begin to extract rare earth materials for electric vehicles and hybrids from sea bottom mud in an area off Minami-Torishima Island, a coral atoll in the Pacific Ocean about 1,900 kilometers southeast of Tokyo. The government’s aim is to reduce the country’s reliance on China for rare earth metals.
In a 2018 open-access paper published in Scientific Reports, a team of Japanese researchers noted that deep-sea mud containing more than 5,000 ppm total rare-earth elements and yttrium (REY content was discovered in the western North Pacific Ocean near Minami-Torishima in 2013. This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features.
Here, we estimated the resource amount in REY-rich mud with Geographical Information System software and established a mineral processing procedure to greatly enhance its economic value. The resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising area (105 km2 × 0–10 mbsf), which accounts for 62, 47, 32, and 56 years of annual global demand for Y, Eu, Tb, and Dy, respectively.
Moreover, using a hydrocyclone separator enabled us to recover selectively biogenic calcium phosphate grains, which have high REY content (up to 22,000 ppm) and constitute the coarser domain in the grain-size distribution. The enormous resource amount and the effectiveness of the mineral processing are strong indicators that this new REY resource could be exploited in the near future.—Takaya et al.
Locality and bathymetric maps of the research area in Takaya et al.. Star symbols show the piston coring sites, and the color-coding corresponds to each research cruise as noted in the legend. The white rectangle shown in the detailed map is the target area where the resource amount estimation was conducted.
Work to develop technologies to extract the resources from depths of 5,000-6,000 meters will begin next year, the report said. The Japan Current—among the world’s fastest sea currents, passes the target area, which is also located in the path of typhoons.
Deep sea oil and natural gas deposits are under strong pressure, which pushes the resources out once a hole drilled from the surface reaches them. However, mud containing rare earth metals does not have this advantage, so it will require some means to bring it up to the surface—pumping, for example.
The Japanese Diet approved an allocation of ¥6 billion ($44 million) for the project in the second supplementary budget for fiscal 2022 recently approved in an extraordinary session. The money will be spent on the development of pumps and making pipe as long as 6,000 meters to be used in trial extraction.
Researchers succeeded in pumping up deposits from a 2,470-meter-deep seabed in a period from August to September.
Japan currently relies on imports for nearly all its rare metal needs, including 60% from China. Japan’s new National Security Strategy announced last Friday states: “Japan will curb excessive dependence on specific countries, carry forward next-generation semiconductor development and manufacturing bases, and secure stable supply for critical goods, including rare earths.”
Takaya, Y., Yasukawa, K., Kawasaki, T. et al. (2018) The tremendous potential of deep-sea mud as a source of rare-earth elements. ˆ 8, 5763 doi: 10.1038/s41598-018-23948-5