Comprehensive recycling method of red mud

The invention relates to a comprehensive recycling method of red mud. The method comprises the following steps: S100, grinding the red mud to obtain red mud powder; s200, a first acid solution is added into the red mud powder for stirring and dissolution, and a first reactant is obtained; the concentration of the first acid solution is 1-6 mol/L; the first reactant comprises corresponding salts which are generated by respectively reacting the Al2O3, the Fe2O3 and the SiO2 with the first acid solution; s300, carrying out solid-liquid separation on the first reactant to obtain an acid leaching solution and acid leaching residues; the corresponding salts are separated into the acid leaching liquid, and the multiple rare earth elements are separated into the acid leaching residues; s400, treating the pickle liquor to obtain silica powder and a water purifying agent; and S500, the acid leaching residues are treated, and scandium oxide, other rare earth element oxides and other rare earth mixed precipitates are obt