Method for recovering lithium from lithium-containing solution

A method for recovering lithium from a lithium-containing solution, comprising:

• (1) precipitating lithium from the lithium-containing solution by a) or b):
• a) regulating the lithium-containing solution by adjusting a pH value of the lithium-containing solution to 5-6, mixing the regulated lithium-containing solution with a meta-aluminate solution, and standing for aging, to obtain a precipitation solution containing a first precipitate of Li(OH)·2Al(OH)3·nH2O, wherein n=1-3;
• during the adjusting of the pH value of the lithium-containing solution, collecting carbon dioxide produced by the lithium-containing solution and injecting the collected carbon dioxide produced by the lithium-containing solution into an alkaline solution to obtain a carbonate;
• and
• regulating the precipitation solution by adjusting a pH value of the precipitation solution to 6-7, and performing filtering and washing on the regulated precipitation solution, to obtain a precipitate of LiaX·2Al(OH)3·nH2O and a first filtrate, wherein X represents an anion of an acid solution used in the adjusting of the pH value of the precipitation solution, and a=1 or 2;
• or
• b) mixing the lithium-containing solution with a meta-aluminate solution to obtain a first mixture, regulating the first mixture by adjusting a pH value of the first mixture to 5-7, standing for aging, and performing filtering and precipitating on the regulated first mixture after the aging, to obtain a precipitate of LiaX·2Al(OH)3·nH2O and a first filtrate, wherein X represents an anion of an acid solution used in the adjusting of the pH value of the first mixture, n=1-3, and a=1 or 2;
• and
• during the adjusting of the pH value of the first mixture, collecting carbon dioxide produced by the lithium-containing solution and injecting the collected carbon dioxide produced by the lithium-containing solution into an alkaline solution to obtain a carbonate;
• (2) desorption of lithium:
• mixing the precipitate of LiaX·2Al(OH)3·nH2O with water in a mass ratio of 1:1 to 1:50 to obtain a second mixture and stirring the second mixture at 20-60° C. for 1-24 hours, and filtering the second mixture to obtain a lithium adsorbent of (1−m)LiaX·2Al(OH)3·nH2O and a first LiaX-containing filtrate, wherein m=0.1-0.9;
• (3) precipitation of lithium:
• evaporating and concentrating the first LiaX-containing filtrate to obtain a concentrated first LiaX-containing filtrate, adding a carbonate into the concentrated first LiaX-containing filtrate to obtain a third mixture, and stirring the third mixture, and performing filtering and washing on the third mixture, to obtain a precipitate of Li2CO3, wherein a molar ratio of lithium in the first LiaX-containing filtrate to a carbonate ion in the carbonate is 1.05:2 to 1.3:2;
• and
• (4) adding the lithium adsorbent to the first filtrate, and performing filtering and washing on the first filtrate to obtain a second precipitate of LiaX·2Al(OH)3·nH2O ;
• and
• performing the desorption of lithium on the second precipitate to obtain a lithium-desorbed filtrate, and precipitating lithium from the lithium-desorbed filtrate.