Method for preparing high specific surface area porous magnesium silicate lithium powder by using salt lake brine after potassium extraction

The invention discloses a method for preparing high specific surface area porous magnesium silicate lithium powder by using salt lake brine after potassium extraction. The method comprises a step 1) of adding deionized water into salt lake brine after potassium extraction at a ratio of 1:1, adding 3-9 M aqueous alkali in the stirring process of 20-50 DEG C, obtaining white solid of magnesium hydroxide and lithium borate, and after stirring for 0.5-8 h at the same temperature, performing filtering, washing and collection; a step 2) of dispersing white solid obtained in the step 1) in the deionized water, adding a silicon source, stirring for 1-6 h at room temperature to obtain reaction slurry, and enabling the solid content in the slurry to be 2-4 wt%; a step 3) of pouring the reaction slurry in a hydrothermal reaction kettle, and reacting for 1-360 h at 100-200 DEG C; a step 4) of centrifuging white sediment after reaction and washing the white sediment to be neutral, and performing drying to obtain the sheet-shaped porous magnesium silicate lithium powder which is high in specific surface area and horizontal-to-vertical ratio. The specific surface area of the obtained magnesium silicate lithium powder is higher than 300 m /g.