Japan Finds Vast Amounts of Rare Earths Underseas

Jul 5, 2011
Atsushi Takano, Nikkei Monozukuri
The estimated sea areas where rare earth-rich mud is located and the estimated amounts of resources
The estimated sea areas where rare earth-rich mud is located and the estimated amounts of resources
[Click to enlarge image]
The collection rates of rare earths with sulfuric acid (upper graph) and hydrochloric acid (lower graph)
The collection rates of rare earths with sulfuric acid (upper graph) and hydrochloric acid (lower graph)
[Click to enlarge image]

A Japanese research group found widely-distributed high-quality rare earth-rich mud in the central and southeastern Pacific Ocean.

The research group is led by Yasuhiro Kato, associate processor at the University of Tokyo's Graduate School of Engineering. The amount of rare earths that exist in the two sea areas is about 1,000 times more than the amount that exists on land.

Currently, there are three types of offshore minerals: hydrothermal sulfide ore deposit, manganese crust ore deposit and manganese nodule ore deposit. But the newly-found rare earth-rich mud is a totally-new offshore mineral resource that is different from those three types.

Specifically, the mud has the following four characteristics. First, it contains large amounts of rare earths. Second, the amount of resources is about 1,000 times more than the amount that exists on land, and the resources can be easily found. Third, it hardly contains radioactive elements that are obstacles to exploitation such as uranium and thorium. Fourth, it is extremely easy to collect rare earths (by using dilute acid for extraction).

Therefore, Kato describes the rare earth-rich mud as "dream-like offshore mineral resource." The thesis about those findings was published in an online issue of Nature Geoscience magazine.

The research group took over 27 piston cores of samples (piston core samples) that the Ocean Research Institute of the University of Tokyo had collected across the Pacific Ocean for paleomagnetic research from 1968 to 1984. And the group started to analyze the whole-rock chemical compositions of 456 types of samples by using an inductively-coupled plasma mass spectrometer (ICPMS) in 2008.

Piston core samples are pillar-shaped sediment samples obtained from sea beds by dropping 5 to 20m-long metal cylinders (piston corers) from ships. By using this method, it becomes possible to collect sediments without cluttering them while keeping the order of the layers.

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