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IPFS News Link • Mines and Mining

Dangling strings slash the time and space needed for lithium harvesting

•, By Ben Coxworth

Currently, lithium-rich brine must be pumped into surface-located manmade ponds, where it's left to sit for anywhere from several months to a few years. Throughout this period, the water itself evaporates into the atmosphere, leaving concentrated salts behind. Lithium is then harvested from those salts.

Besides taking a long time, this process also requires a lot of land for the large evaporation ponds. Additionally, in order to make such huge operations economically feasible, most of them must be located in the few places that have large and plentiful underground lithium brine deposits. These locations must also have arid climates that boost evaporation.

With such drawbacks in mind, Prof. Z. Jason Ren and colleagues at Princeton University have devised a new lithium-extraction process. It yields usable lithium within less than one month, occupies about 10% as much land as the ponds, and is worthwhile utilizing in a wide variety of locations where even modest amounts of lithium brine are present.

The technique incorporates strings made from inexpensive twisted cellulose fibers. Each of those porous fibers has a hydrophilic (water-attracting) core, surrounded by a hydrophobic (water-repelling) surface.

Arrays of these strings are hung over brine-filled reservoirs, with the bottom end of each string immersed in the liquid. Capillary action draws the liquid up the cores of the strings' fibers, while the surfaces of those fibers push the liquid out into the air where its water content quickly evaporates.

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