Method for separating iron element in brine and application thereof

A method for separating iron element in brine, comprising:

• adding a pH adjusting agent to the brine to adjust pH of the brine to 6.0-7.0, and controlling a temperature of the brine to 75° C.-90° C.;
• introducing an oxygen-containing gas into the brine, to covert the iron element in the brine into magnetic iron oxide, wherein the oxygen-containing gas comprises oxygen molecules, and based on one mole of iron in the brine, the oxygen molecules are configured to be introduced in an amount of 250-540 mol and at a rate of 4.5-10 mol/min to fully convert ferrous ions in the brine into the magnetic iron oxide;
• and
• separating the magnetic iron oxide from the brine by magnetic adsorption, to obtain an iron-removed brine, and to recover magnetite by a magnetic separator, wherein the magnetic separator is configured to stir the brine simultaneously with the introducing of the oxygen-containing gas,
• wherein the iron-removed brine is directly used in an extraction process of lithium without adjusting pH of the iron-removed brine, and
• wherein the recovered magnetite has diffraction peaks that are consistent with diffraction peaks of magnetic iron oxide.