From the patent for reference. Note acid and water are...

From the patent for reference. Note acid and water are recycled.

The ion exchange system for selective lithium uptake (1601) comprises an ion exchange media and an ion exchange reactor setup. The ion exchange media comprises Li.sub.4Mn.sub.5O.sub.12 particles with a protective coating to prevent dissolution and degradation of the particles. The ion exchange reactor setup comprises a set of 50 stirred tank reactors containing ion exchange media, wherein stirring is used to contact the media with alternating flows of brine, water, and acid. When the media is contacted with the brine, the media absorbs lithium from the brine and releases protons. Sodium hydroxide is added to the brine to maintain the pH of the brine in the range of about 4-7. After 85% of the lithium has been recovered from the brine and absorbed into the media, the brine is removed from the tank, and the tank is washed with water to remove residual brine. Then, acid is used to elute lithium with the ion exchange media absorbing protons and releasing lithium ions to produce a lithium eluate solution. The brine contains 200 mg/L Li, 100,000 mg/L Na, 3,000 mg/L Ca, and 2,000 mg/L Mg. The acid is aqueous 1.0 N sulfuric acid. The lithium eluate solution contains 5,000 mg/L Li and impurities including Na, Mg, and Ca.

The reverse osmosis system (1602) is used to remove water from the lithium eluate solution. The permeate from the reverse osmosis system is water, which is reused in the integrated system. The retentate contains a concentrated lithium sulfate solution with a lithium concentration around 15,000 mg/L.

The evaporative concentrator system (1603) is used to remove more water from the lithium eluate solution, and the water is reused in the integrated system. The evaporative concentrator yields a further-concentrated lithium sulfate solution with a lithium concentration around 25,000 mg/L.

The neutralization and purification system (1604) combines the further-concentrated lithium chloride solution with NaOH and Na.sub.2CO.sub.3 to neutralize the solution and precipitate multivalent cations as hydroxide and carbonate solids such as CaCO.sub.3, Mg(OH).sub.2, and other precipitates. The neutralization and purification system further used ion exchange resins to remove trace amounts of Mg, Ca, B, and other impurities from the solution. The product of the neutralization and purification system is a concentrated monovalent chloride solution containing Li, Na, and K.