Spooked by the Chinese embargo of rare earth elements the rare earth mining industry is busily looking and investing in rare earth mineral extraction.  Several prospects look practical.  Meanwhile Japan’s Yasuhiro Kato, associate processor at the University of Tokyo’s Graduate School of Engineering is leading a research group that’s found widely distributed high-quality rare earth-rich mud in the central and southeastern Pacific Ocean.

Pacific Undersea Rare Earth Element Deposits. Click image for the largest view.

First one asks is that kind of deposit possible to gather and how deep? Kato notes the mineral resources are distributed 3,500 to 6,000 meters below the surface of the sea, it is possible to mine and collect more than 40 million tons of rare earth-rich mud every year with existing technologies. Plus, the rare elements can be extracted from the collected mud in a short time by using, for example, dilute sulfuric acid.

And Japan is out in front on the legal access matter.  The deposits are out in the high seas, but it is possible for Japan to obtain mining areas if it meets some conditions such as an agreement with the International Seabed Authority.  This is doable.  Maybe the Chinese idea of an embargo isn’t turning out to be the best marketing idea after all.

Kato’s research group took over 27 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. Piston core samples are pillar-shaped sediment samples obtained from seabeds by dropping 5 to 20 meter long metal cylinders called piston corers, from ships. By using this method, it becomes possible to collect sediments without cluttering them while keeping the order of the layers. The researchers started to analyze the whole-rock chemical compositions of 456 types of samples by using an inductively coupled plasma mass spectrometer in 2008.

They found the rare earth-rich mud with quality equivalent to that of the ion adsorptive ore deposit in southern China.  The effective territory covers a wide area of the Pacific Ocean. Ion adsorptive ore deposits are formed when rare earths are adsorbed by clay minerals concentrate on soil made of weathered granite.

It has been thought this level of deposits was found only in southern China such as Jiangxi and Hunan provinces. The ocean deposits also contain large amounts of heavy rare earths including dysprosium and terbium, and most of these rare earths can be extracted just by using dilute acid to leach them out.

The statistical analysis shows rare earth-rich mud with an average thickness of 8.0 meters and an average gross rare earth density of 1,054 parts per million in the southeastern Pacific Ocean and the mud in the central Pacific Ocean with an average thickness of 23.6 meters and an average gross rare earth density of 625 parts per million.

Kato notes if rare earth-rich mud is harvested in a 4 km2 (1.2 mile sided square) area at a depth of 10 meters such as at “Site 76,” which is located in the southeastern Pacific Ocean, it would potentially provide the amount of rare earths equivalent to the amount consumed in Japan in one or two years.

There are other valuable minerals in the mud, too.  Site 76 contains concentrated amounts of rare metals such as vanadium, cobalt, nickel and molybdenum.

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 analysis shows rich deposits, the resource is huge and there are only tiny amounts of problematic radioactive elements like uranium and thorium.

The issue may be can the Japanese industrials get a project going.  Kato’s group isn’t saying what the cost projections might be; perhaps the skill set to figure it isn’t in the group.  But there are likely number crunchers looking into the idea as you read this.  The Japanese and suppliers world wide, every consumer of sophisticated products and even the U.S. Congress noted the embargo China used last year.

If anyone can get the minerals up at low cost it will be the Japanese. Cooperation with the resources in Korea may come into the matter, too.  Between them or going it alone there is little doubt if the numbers work some means of harvesting rare earth elements is going to come to market.  A sure point is if it does – it will be at substantial scale.

A year ago there was concern about adequate rare earth element supplies to keep industries outside of China going.  Now it’s looking more like a race to fill the gap until the new mines and new ocean deposits can get to market.  The worry isn’t over, but the concerns have changed.


1 Comment so far

  1. MattMusson on July 7, 2011 7:20 AM

    The Japanese have been developing Kelps and seaweeds that remove heavy metals from seawater. I wonder if enough of this rare earth rich mud is near the surface where plants could be used to extract it?

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