Brine refining method and device for extracting lithium from salt lake

The invention relates to the technical field of salt chemical industry, and relates to and discloses a brine refining method for extracting lithium from a salt lake. The method comprises the following three steps: pretreatment, nanofiltration to remove sulfate and nanofiltration to remove carbonate. According to the method, sulfate and carbonate in the brine are respectively removed by adopting a nanofiltration device by controlling the pH value, the operation pressure of a nanofiltration system is reduced, and the recovery rate of lithium is improved by washing concentrated water. The invention further discloses a brine refining device for extracting lithium from the salt lake. The device comprises two or more membrane separation modules and a concentrated water adjusting device, and is provided with a water inlet and concentrated water balance valve group, so that the cut-in and cut-out operation of a single membrane separation module in the device can be realized under the condition of normal high-pressure