Researchers at Pacific Northwest National Laboratory and LCW Supercritical Technologies have created five grams of yellowcake — a powdered form of uranium used to produce fuel for nuclear power production — using acrylic fibers to extract it from seawater.
LCW, a Moscow, Idaho clean energy company with early support from PNNL through DOE’s Office of Nuclear Energy, developed an acrylic fiber which attracts and holds on to dissolved uranium naturally present in ocean water.
LCW is applying for further SBIR funding for a uranium extraction field demonstration, to be led by PNNL, in the Gulf of Mexico, where the water is much warmer. The material performs much better in warmer water and extraction rates in the Gulf are expected to be three to five times higher, therefore making it more economical to obtain uranium from seawater.
They have chemically modified regular, inexpensive yarn, to convert it into an adsorbent which is selective for uranium, efficient and reusable,” said Chien Wai, president of LCW Supercritical Technologies.
The adsorbent material is inexpensive, according to Wai. In fact, he said, even waste yarn can be used to create the polymer fiber. The adsorbent properties of the material are reversible, and the captured uranium is easily released to be processed into yellowcake. An analysis of the technology suggests that it could be competitive with the cost of uranium produced through land-based mining.
PNNL researchers have conducted three separate tests of the adsorbent’s performance to date by exposing it to large volumes of seawater from Sequim Bay next to its Marine Sciences Laboratory. The water was pumped into a tank about the size of a large hot tub.
Seawater contains about three parts per billion of uranium. It’s estimated that there is at least four billion tons of uranium in seawater, which is about 500 times the amount of uranium known to exist in land-based ores(PDF), which must be mined.
Mining of underground uranium has environmental challenges not encountered with extracting it from the oceans. And Wai says the fibers, which have affinity for more heavy metals than just uranium, can likely be used one day to clean up toxic waterways themselves. He says the fibers have potential to extract vanadium, an expensive metal used in large-scale batteries, from the oceans instead of mining it from the ground.