The invention relates to a
lithium extraction method based on extraction-back extraction, which comprises the following steps: carrying out extraction and phase separation on a
lithium-containing solution by using a composite extraction liquid to obtain a
lithium-containing loaded
oil phase, the composite extraction liquid comprises an extraction agent and a
diluent, and the
diluent is selected from 1, 2, 3-trimethyl-1, 3-pentanediol monoisobutyrate or 1, 2, 3-trimethyl-1, 3-pentanediol monoisobutyrate. The
crown ether is at least one of 2, 3-dipropoxy
crown ether, 15-
crown ether-5, dibenzo-18-crown
ether-6, calix [4] arene, calix [6] arene, calix [8] arene, tricyclodecenyl acetate,
benzothiazole and 7-(4-ethyl-1-methyl octyl)-8-hydroxyquinoline; cO2 is introduced into the lithium-containing loaded
oil phase to be mixed, a gas-liquid mixture is obtained, then the gas-liquid mixture is mixed with water to be subjected to reverse extraction and phase separation, and reverse extraction liquid is obtained; and carrying out heat treatment on the strip liquor to obtain
lithium carbonate. According to the invention, CO2 is firstly introduced into the lithium-containing loaded
oil phase for mixing, so that CO2 gas molecules can be effectively dispersed and adsorbed in pore channels, the
utilization rate of CO2 is improved, the
energy consumption can be effectively reduced, and the production efficiency is improved.