Scientists make 'huge' $540 billion discovery at the bottom of a giant lake

[Bernardo de La Paz]

12. Filters would be expensive. Just dry it in large ponds in the sun. Lots of sun there

Your point is good though: extraction from the brine is not difficult.

Filters are good for removing small quantities of impurities. I'm no expert, but I think industrial scale extraction would be easiest by drying. Then the lithium can be scooped up by front loaders and refined. Like salt (sodium chloride) is dried in the sun and scooped up by front loaders.

If there are large portions of salt or potassium salts or other dissolved salts, then refine is more involved, but even then I think it is not difficult. There may be ways of doing gravity/centrifuge separation or selective precipitation. As the proportion of water declines by evaporation, different salts begin precipitation ahead of others. Lithium might come out early or late.