Distribution of average ΣREY contents for surface sediments (less than 2 meter in depth) in the Pacific Ocean.
World demand for rare-earth elements and the metal yttrium—which are crucial for novel electronic equipment and green-energy technologies—is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these elements. However, seafloor sediments have not been regarded as a rare-earth element and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the elemental composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-earth elements and yttrium at numerous sites throughout the eastern South and central North Pacific. 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. Uptake of rare-earth elements and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-earth elements and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these elements.
Rare-earth elements are crucial for novel electronic equipment and green-energy technologies and world demand is rapidly increasing. Associate Professor Yasuhiro Kato and his team at the Department of Systems Innovation of the University of Tokyo’s Graduate School of Engineering have discovered a new type of mineral resource, named REY (rare-earth elements and yttrium)-rich mud, distributed in vast quantities throughout a large part of the Pacific Ocean. REY-rich mud containing up to approximately 0.2 percent by weight total REY occurs across the central north and southeastern Pacific Ocean in average thicknesses of approximately 24 m and 8 m, respectively. Our data show that REY stored in these Pacific mud deposits amounts to a possible resource 100 to 1,000 times greater than the world’s current land reserves of 110,000,000 tonnes of REY oxides, depending on local stratigraphic continuity and thickness of the REY-rich mud. Uptake by materials such as hydrothermal Fe-oxyhydroxides and phillipsite seems to be responsible for the high REY content, and consequently REY are readily recovered by simple acid leaching and are a suitable resource for development. The newly discovered REY-rich mud may constitute a highly promising source of rare earth elements.
Nautilius Minerals developing ocean floor mining