The size of lithium reserves in the world’s oceans are estimated to be 230 billion tons, that is ca. 5000 times as big as land-based resources. Concentration: 0.17 mg/liter or 0.2 ppm. Chinese scientists, employed by the King Abdullah University of Science and Technology in Saudi-Arabia, have proposed a method for extracting lithium from seawater, a process they claim is economically viable.
To address this issue, the team led by Zhiping Lai tried a method that had never been used before to extract lithium ions. They employed an electrochemical cell containing a ceramic membrane made from lithium lanthanum titanium oxide (LLTO).
Lithium has atom number 3, so is very small. The membrane’s holes are so small that they only let lithium-ions through, propelled by electricity. The lithium-enriched water is further processed in four more steps, to end up with a lithium concentration of 9,000 ppm. Eventually, lithium phosphate is the useful end product. As a bonus, the process delivers hydrogen, chlorine and desalinated water. Electricity cost: $5 per kilo of lithium. The very sunny Red Sea area would be ideal for lithium plants, driven by solar electricity, and is probably the reason why the King Abdullah University funded the research.
[mining.com] – ‘Cheap and easy’ method to extract lithium from seawater
[pubs.rsc.org] – Continuous electrical pumping membrane process for seawater lithium mining (Original publication)
[sea4value.eu] – Sea4value project site
[wikipedia.org] – Brine mining