Locality and bathymetric maps of the research area. Source: Takaya et al.

An area of deep-sea mud in the western North Pacific Ocean near Minami-Torishima Island, Japan, contains more than 16 million tons of rare-earth elements and yttrium (REY). Japanese researchers estimate that this region could supply yttrium, europium, terbium and dysprosium for 780, 620, 420 and 730 years, respectively, and has the potential to supply these metals on a “semi-infinite” basis to the world.

Seven deep-sea mud core samples obtained at 5,600 to 5,800 meters below sea level during a research cruise conducted in the Japanese Exclusive Economic Zone were analyzed to investigate the distribution of REY near the seafloor. Deep-sea sediments containing 2,000 ppm to more than 5,000 ppm REY were located only a few meters below the seafloor. Critical information on depth distribution and thickness of REY-rich mud was easily collected by sub-bottom profiler on shipboard.

After dividing the study area in 24 grid squares, the resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising squarw, which accounts for 62, 47, 32 and 56 years of annual global demand for yttrium, europium, terbium and dysprosium, respectively.

The team also proposed new deep-sea mineral processing techniques, including the use of a hydrocyclone separator, which could enhance the economic value of these resources.

Scientists from Waseda University, University of Tokyo, Japan Agency for Marine-Earth Science and Technology, Chiba Institute of Technology, Kobe University, Tokyo Institute of Technology and Toa Corporation participated in this research, which is published in Scientific Reports.