Method for preparing calcium carbonate from steel slag

The invention relates to the technical field of environmental engineering, and discloses a method for preparing calcium carbonate by using steel slag, which comprises the following steps: (1) grinding the steel slag to obtain steel slag micropowder with the particle size of less than or equal to 100 mu m; (2) carrying out leaching reaction on the steel slag micro powder by using a leaching agent to obtain a mixture; (3) the mixture is subjected to static settlement and solid-liquid separation, and a calcium-rich solution and calcium-poor steel slag are obtained; (4) introducing CO2-containing flue gas into the calcium-rich solution, carrying out a reaction, then carrying out solid-liquid separation, and drying the obtained solid product to obtain calcium carbonate; the leaching agent is selected from one or more than two of an ammonium chloride solution, an ammonium nitrate solution, an ammonium sulfate solution and an ammonium acetate solution. According to the method provided by the invention, calcium ions