This study introduced a high-value green processing solution for copper tailings to prepare high-purity vaterite from gold-copper tailings. The active reaction components were determined through Gibbs free energy calculations. The study discusses the impact of different experimental parameters on the leaching rate of Ca2+ and the degree of mineralization in gold-copper tailings, and then considers the influence of different dispersants on improving the stability of vaterite. The results show that the optimal leaching efficiency of Ca2+ in the NH4Cl solution is 75%, and the optimal mineralization efficiency is 87%. Under appropriate mineralization conditions, vaterite CaCO3 with d50 < 12 μm, a purity of 98%, and a whiteness of 98.7% can be prepared. The precipitated vaterite is affected by the pH swing method connected with the neutralization reaction. The presence of excess NH3 and supersaturated CO2 are necessary for the formation of vaterite-type CaCO3. Morphological analysis results show that dispersants such as polyacrylamide and sodium tripolyphosphate can improve the dispersibility of vaterite, preventing agglomeration and enabling its stable existence in aqueous solutions. Nanoparticle aggregation and crystal growth are two possible mechanisms for the formation of vaterite. The leaching-mineralization cycle technology using NH4Cl as the leaching solution meets the requirements for CO2 removal and alkaline industrial waste residue treatment, while avoiding the significant consumption of chemical reagents in traditional mineralization. This method provides a pathway for producing vaterite using copper tailings and has a broad market prospect.