Method for synthesizing ultrafine calcium carbonate by utilizing carbide slag

The invention relates to a method for synthesizing ultrafine calcium carbonate by utilizing carbide slag. The method comprises the following steps of: (1) dissolving carbide slag: uniformly mixing carbide slag with water in a ratio of (1:6)-(1:20) to ensure that the carbide slag is fully dissolved into a turbid liquid, wherein the water content of the carbide slag is 20-45%; (2) carrying out impregnation reaction: adding ammonium chloride into the turbid liquid of the carbide slag for uniformly mixing, wherein the mass ratio of carbide slag to ammonium chloride is (1:0.7)-(1:2.5), after the impregnation reaction is finished, filtering and removing the slag to obtain a clear calcium chloride solution; and (3) carrying out carbonization reaction: adding a crystal form control agent into a calcium chloride solution for fully dissolving, introducing CO2 into the solution to carry out carbonization reaction till the pH (potential of Hydrogen) value of the reaction solution is less than or equal to 7 to obtain ultrafine calcium carbonate slurry, wherein the crystal form control agent is one or more than two mixtures of sulfate, chloride, citrate, sodium dodecyl benzene sulfonate, pyrophosphate, oleic acid, ammonium citrate, N-methyl pyrrolidone and maleic acid.