Method for removing fluorine ions in wastewater

The invention discloses a method for removing fluorine ions in wastewater, which comprises the following steps: 1, adding 30-50% of white sand based on 100% of the total volume of a stirring barrel, then adding fluorine-containing wastewater, carrying out first stirring, then adding a sodium metaaluminate solution, adjusting the pH value of a mixed solution to be greater than 11, stirring, standing and layering to obtain a first mixed solution at the upper layer; 2, based on 100% of the total volume of a stirring barrel, adding 30-50% of white sand, then adding the first mixed solution, stirring, then adding sulfuric acid to adjust the pH value to 6.5-7.5, and standing for layering to obtain a second mixed solution on the upper layer; and step 3, adding the second mixed solution into a stirrer, then adding expanded graphite, introducing mixed gas of oxygen, carbon dioxide and argon, mechanically stirring at the speed of 200-300r/min, simultaneously carrying out ultrasonic oscillation, then adding yttrium hydr