Abstract: Calcium carbonate was prepared by carbon dioxide bubbling carbonation reaction with calcium chloride as the source of calcium and zinc nitrate as the additive.The influences of various factors on the preparation of calcium carbonate by bubbling carbonation were explored and the process was optimized by the single factor variable method.The effects and mechanisms of operation parameters，such as ammonia amount，CO₂ flow rate，carbonization temperature，carbonization time，and zinc nitrate amount on the morphology and structure of the calcium carbonate were investigated by XRD and SEM.Under the optimum condition as the ammonia volume fraction of 2.4%，CO₂ flow rate of 180 mL/min，carbonization time of 30 min，carbonization temperature at 30 ℃，and zinc nitrate of 0.002 mol，spherical calcium carbonate particles with well single crystal form could be prepared.Possible formation mechanism of calcium carbonate in the CaCl₂-CO₂-CaCO₃ system was proposed and confirmed by designed positive-negative titration experiment.

Key words: bubbling carbonation, zinc nitrate, CO₂, calcium carbonate, calcium chloride