Comprehensive utilization method for steel making slag

A method for comprehensive utilization of steelmaking slag, comprising following steps:

• S1, leaching free calcium oxide from the steelmaking slag using a first ammonium chloride solution, followed by a solid-liquid separation to obtain a first leaching residue and a first mineralized solution, and performing CO2 absorption and mineralization on the first mineralized solution to obtain calcium carbonate and an ammonium chloride solution;
• S2, leaching the first leaching residue using a second ammonium chloride solution, followed by a solid-liquid separation to obtain a second leaching residue and a mineralized crude solution, subjecting the mineralized crude solution to an oxidation, an alkali adjustment and a solid-liquid separation to obtain an iron-aluminum precipitate residue and a second mineralized solution, and performing CO2 absorption and mineralization on the second mineralized solution to obtain a crude calcium carbonate and an ammonium chloride solution;
• S3, leaching the iron-aluminum precipitate residue using a sodium hydroxide solution, followed by a solid-liquid separation to obtain an iron hydroxide precipitate and a sodium metaaluminate solution, performing CO2 absorption and mineralization on the sodium metaaluminate solution to obtain an aluminum hydroxide precipitate and a sodium carbonate solution, and treating the sodium carbonate solution with carbide slag to obtain a crude calcium carbonate and a sodium hydroxide solution.