Necessity is the mother of invention they say. Rarely have we seen as much of a crisis in the metals consuming industry as we see at the moment with Rare Earth supplies. In the week that the Telegraph reports China has further tightened its stranglehold on the supply of rare earths by limiting the number and type of firms allowed to mine the 17 rare earth elements in future, a Reuters article reports that the Japanese have discovered vast reserves of rare earth minerals in ocean floor muds. “The deposits have a heavy concentration of rare earths. Just one square kilometre (0.4 square mile) of deposits will be able to provide one-fifth of the current global annual consumption,” estimates Yasuhiro Kato, an associate professor of earth science at the University of Tokyo working with a team of researchers from the Japan Agency for Marine-Earth Science and Technology. Mr Kato said the sea mud contained especially rich heavier rare earths such as gadolinium, lutetium, terbium and dysprosium, although as we see below especially is a relative term.
The deposits lie in international waters east and west of Hawaii, as well as east of Tahiti the article advised. Reuters quotes Mr. Kato as estimating rare earths contained in the deposits amounted to 80 to 100 billion tons, compared to global reserves currently confirmed by the U.S. Geological Survey of just 110 million tons. But others also question those numbers. Our friend Gareth Hatch on his TMR blog post does some pretty damming number crunching on the accuracy of these figures and raises the very serious question of economics which we will come back to shortly.
Numerous challenges remain before this discovery can hope to contribute anything to global supplies, not least of which include environmental concerns. The reports suggest that through a leaching process, the ocean sediments can yield the rare earth salt in surface ships using mild acids. But if one takes the Chinese at face value, the main reason they have restricted exports, and eradicated non officially licensed mining involves the prevention of widespread environmental damage caused, at least in part, by the use of acid leaching. As the thinking goes, if leaching requires strong acids on land why would only weak acids work at sea? And what happens to the remaining acids after the leaching process? Does they get stored on board for recycling back on land or does it just get dumped overboard into the Pacific Ocean? Will we see plumes of environmentally damaging acids from satellite images in years to come or will domestic standards apply in this international environment to ensure proper environmental responsibility?
But perhaps we have gotten ahead of ourselves. The immediate challenge facing exploitation of these resources involves a physical one. The minerals in the sea mud would come from depths of 3,500 to 6,000 metres (11,500-20,000 ft) below the ocean surface at 78 locations (although only about a third of the sites tested showed sufficiently rich concentrations deemed economically viable). Just lifting large volumes of sediment thousands of feet from the ocean floor will prove a significant (if not insurmountable) engineering challenge. The sediment then has to get returned to the sea bed in a place and manner that does not disrupt the ongoing extraction of fresh sediment. Gareth, quoting the original report, details the REE concentrations which at 0.1-0.22% may appear economically viable on land but not after lifting a ton of mud a mile from the sea floor.
We don’t know where these muds originally came from but they could have come as a result of erosion from land based deposits or possibly from volcanic activity. One beneficial feature, however, relates to the relatively low levels of thorium present in the muds making treatment and disposal less costly and of lower risk to the environment. We wrote just last week about the concerns of radiation and environmental contamination in Malaysia at Lynas’ new treatment plant, in part due to the risk of thorium release.
One slightly mischievous thought that occurred to the team here at MetalMiner – regardless of economic viability, who has greatest claim over these deposits? They may lay in international waters but from the description in the articles, they seem a lot closer to the US state of Hawaii than to Japan.