The invention discloses a method for preparing nano CaCO3 from
carbide slag, which comprises the following steps: preparing a phase
transfer agent solution, adding
carbide slag, reacting and filtering to obtain a phase transfer solution; and diluting the phase transfer liquid with deionized water to obtain a carbonized precipitate
raw material liquid with the Ca < 2 + > concentration of 0.8-1.5 mol.L <-1 >, adding a
crystal form control agent and
ammonia water into the carbonized precipitate
raw material liquid, introducing CO2, stirring to react until the pH value is 7.5-9.0, filtering, washing and
drying to obtain the nano CaCO3. According to the method, the
carbide slag is used as a
raw material, the
industrial waste gas CO2 is used as a carbonizer, high-quality nano CaCO3 with
small particle size, uniform particle size and good
dispersity is prepared, waste is treated with waste, and waste is turned into wealth, the method conforms to the economic cycle development strategy and the double-carbon strategy targets, and meanwhile high-value utilization of the carbide slag is achieved; besides, the nano CaCO3 with the average particle size of 20-40nm is prepared by adopting the
carbonization precipitation raw material solution with relatively high initial Ca < 2 + > concentration, the production efficiency is high, meanwhile, various materials are fully utilized by adopting a circulating process, and the preparation process is mild in operation condition and green and environment-friendly.