Method for extracting lithium from salt lake brine
The present disclosure provides a method for extracting lithium from salt lake brine, which includes: flowing the salt lake brine through a lithium adsorbent at a varying flow rate to obtain a lithium-rich adsorbent, where the lithium ions in the salt lake brine are adsorbed on the lithium adsorbent, and where during the adsorption process, the flow rate of the salt lake brine decreases, and a difference between the initial flow rate and the final flow rate of the salt lake brine is 0.5-3 BV/h; washing the lithium-rich adsorbent; and desorbing the lithium ions from the washed lithium-rich adsorbent with a lithium ion eluent, to obtain a desorption solution.
1 . A method for extracting lithium from salt lake brine, comprising:
flowing the salt lake brine through a lithium adsorbent at a varying flow rate to obtain a lithium-rich adsorbent, wherein lithium ions in the salt lake brine are adsorbed on the lithium adsorbent, and wherein during the adsorption process, the flow rate of the salt lake brine decreases, and a difference between an initial flow rate of the salt lake brine and a final flow rate of the salt lake brine is 0.5-3 BV/h;
washing the lithium-rich adsorbent; and
desorbing the lithium ions from the washed lithium-rich adsorbent with a lithium ion eluent, to obtain a desorption solution.
2 . The method according to claim 1 , wherein the initial flow rate of the salt lake brine is 2.0-3.0 BV/h, and the final flow rate of the salt lake brine is 1.2-1.8 BV/h.
3 . The method according to claim 1 , wherein a total amount of the salt lake brine to be adsorbed is 6-8 BV, and a total adsorption time of the salt lake brine is 2.5-4 h.
4 . The method according to claim 1 , wherein
the washing the lithium-rich adsorbent comprises a first wash, a second wash, and a third wash; and
a flow rate of a first detergent in the first wash, a flow rate of a second detergent in the second wash, and a flow rate of a third detergent in the third wash are increased sequentially, and an amount of the second detergent is greater than an amount of the first detergent or an amount of the third detergent.
5 . The method according to claim 4 , wherein
in the first wash, the flow rate of the first detergent is 3-5 BV/h, and the amount of the first detergent is 0.5-1 BV;
in the second wash, the flow rate of the second detergent is 6-8 BV/h, and the amount of the second detergent is 1-1.5 BV; and
in the third wash, the flow rate of the third detergent is 9-12 BV/h, and the amount of the third detergent is 0.5-1 BV.
6 . The method according to claim 4 , wherein the first detergent comprises an aqueous solution having magnesium ions with a concentration of 50 g/L or less and lithium ions with a concentration of 300 mg/L or less; the second detergent comprises an aqueous solution having magnesium ions with a concentration of 5 g/L or less and lithium ions with a concentration of 250 mg/L or less; and the third detergent is pure water.
7 . The method according to claim 1 , wherein during desorbing the lithium ions, the lithium ion eluent is water, and a temperature is controlled at 30-50° C.
8 . The method according to claim 1 , wherein the lithium adsorbent comprises an adsorbent material, a binder, and a wetting and dispersing agent, the binder comprises at least one of a vinylidene fluoride-chlorotrifluoroethylene copolymer or a fluoroolefin-vinyl ether copolymer, and the wetting and dispersing agent comprises one or more of polyethylene glycol, sodium polyacrylate, polyvinyl alcohol, or a formaldehyde condensate.
9 . The method according to claim 8 , wherein based on a weight of the lithium adsorbent, a content of the adsorbent material is 80-95 wt %, a content of the binder is 4-17 wt %, and a content of the wetting and dispersing agent is 1-5 wt %.
10 . The method according to claim 8 , wherein a ratio of a weight of the adsorbent material to a total weight of the binder and the wetting and dispersing agent is 8:1 or more.
11 . The method according to claim 8 , wherein the binder is 8-12.5 wt % of the adsorbent material.
12 . The method according to claim 8 , wherein a molecular weight of the vinylidene fluoride-chlorotrifluoroethylene copolymer or the fluoroolefin-vinyl ether copolymer is 100,000-800,000.
13 . The method according to claim 1 , before flowing the salt lake brine through the lithium adsorbent at the varying flow rate, desorbing the lithium ions from the lithium adsorbent.
14 . The method according to claim 1 , a flow rate of the lithium ion eluent is 1.5-2.5 BV/h.
15 . The method according to claim 1 , a desorption time of desorbing the lithium ions from the washed lithium-rich adsorbent is 2.5-4 h.