Japan could use old cloth dipped in persimmon juice to enable cheaper extraction of uranium and rare earths from seawater

Research has been underway in Japan on technologies to recover traces of uranium contained in seawater. One of the technologies uses a method involving submerging a material that adsorbs uranium in the sea, and chemically separating and refining the collected uranium after the adsorbent material is pulled out of seawater. The cost of recovering uranium through this method is estimated to be about three-fold higher than the current market price of uranium, research and development efforts for cost reduction are also in the works. Costs could be reduced by 40% or more. This would make it about 1.8 times higher than current uranium prices. Plus Japan could get some Vanadium at the same time. Rare earth that they need. Contribution of vanadium would lower uranium costs by $4 per pound.

Genetically engineered seaweed to have the tannins in Perisimmons and with similarities in fiber to the cotton may be a path to affordable large scale uranium from seawater. The seaweed could also have uses for biofuel to help offset costs with another useful biproduct.

UPDATE : The outline of how Japan has considered scaling up ocean mining using either engineered seaweed or treated cotton or polymer adsorpants. They would put a lot of material in the path of an ocean current and scale it to extract thousands of tons of material each year.

The Japan Atomic Energy Agency (JAEA) conducted experiments in 1999 and 2001 in the sea off Japan using a uranium adsorbent having an amidoxime structure, which reacts sensitively only with heavy metals. The second experiment succeeded in collecting 1.5 g of uranium for each kg of the adsorbent over a period of 30 days. Based on this result, the cost of recovering 1 kg of uranium can be estimated to be about 32,000 yen, about three times higher than the current uranium price on the market. However, because this method allows vanadium, a rare metal, to be recovered together with uranium, there is a potential for reducing the cost burden, according to JAEA.

The Central Research Institute of Electric Power Industry (CRIEPI) has been studying a technology that uses tannin, which is a natural compound, in its uranium adsorbent. The cost of the required raw materials is only one-third of that for the adsorbent studied by JAEA, and an estimate suggests that the total cost could be about 40% lower.

These research and development projects are currently undertaken by a very small number of researchers even with JAEA and CRIEPI combined. They are also faced with insufficient budgets. Nevertheless, attention from overseas countries is growing and the researchers have been receiving inquiries from countries including France and Middle Eastern countries, as well as the United States Department of Energy (DOE).

One ton of seawater contains about 3.3 mg of uranium. By calculation, there is expected to be about 4.5 billion tons of uranium in all of the seawater on earth. Studies on uranium recovery have been carried out in Japan since the 1970s against the background of scarce resources in the country.

CRIEPI uranium from sea water uses a special fabric. The fabric should be dyed in re-fermented oriental persimmon juice. Such juice contains tannin which combines together molecules of sea water uranium.

Asahi – Plant dye used to extract uranium from seawater

The Central Research Institute of Electric Power Industry is employing a method in which uranium is collected on old cloth dyed with a substance taken from persimmons. Researchers said the process reduces the cost of materials to about one-third compared with recovery methods using chemicals.

“Besides uranium, it may also be possible to use (the method) to recover rare metals,” said senior researcher Nobuyuki Tanaka.

The researchers found that the cheapest method was similar to “kakishibu” dyeing, in which old cotton cloth is dyed in persimmon tannin. The total cost could be reduced by about 40 percent.


We have been tracking the Japanese and Russian efforts to extract uranium from seawater for a number of years.

This article had the main details on the adsorpant method.

The japanese process is to use irradiated polymers and stick a braided net of it into the ocean and basically “fish” for 30-90 days for Uranium.

There are other rare metals in seawater. Lithium seems like a valuable target. Its price is in the $80/kg range and there is concern about having enough Lithium for lithium ion batteries. There is 56 times as much Lithium as Uranium in seawater. At $80/kg it would be a $14,000 trillion resource.

Japan is looking at eventually ramping to large scale ocean mining

Akira Nakajima has done a lot of work on using persimmon to absorp heavy metals.

Tannin at wikipedia

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