Abstract: Epigranular nano CaCO₃ was prepared under high initial Ca²⁺ concentration from calcium carbide residue, using NH₄Cl and CO₂ as leaching and carbonation agent, respectively. STP(sodium tripolyphosphate) mixed with PEG-10000(polyethylene glycol-10000) was screened as the more suitable compound additives. The influence of dosage of additives, reaction temperature and the flow rate of CO₂ on the particle size of the sample was investigated. The optimum synthesis conditions of nano CaCO₃ were determined as follows:dosage of STP and PEG-10000 was 3% and 1.5% respectively, the reaction temperature was 25℃, the flow rate of CO₂ was 400mL/min. Under the optimum condition, the nano CaCO₃ prepared were pure metastable state vaterite type with uniform particle size and good dispersion. The average particle size of the CaCO₃ samples was about 45nm with average crystallite size of 20nm. The calcium carbonate samples were characterized by X-ray powder diffraction device (XRD), scanning electron microscopy (SEM) and fourier infrared spectrometer (FTIR),these resultants were used to analyze the possible influence mechanism on the particle size of the reaction temperature and the flow rate of CO₂. And the resultants were also used to further discuss the action mechanism of compound additives.

Key words: nano calcium carbonate, agglomeration, particle size distribution, synthesis, carbon dioxide

摘要： 以电石渣为原料，NH₄Cl为浸取剂，CO₂为碳化剂，在较高Ca²⁺初始浓度条件下制备粒度均匀的纳米CaCO₃。筛选并确定三聚磷酸钠（STP）和聚乙二醇（PEG）-10000为较适宜的复合添加剂；考察了添加剂用量、反应温度、CO₂流率的变化对样品粒径的影响，所确定较适宜的纳米CaCO₃合成工艺条件为：STP和PEG-10000用量分别为3%和1.5%，反应温度25℃，CO₂流率400mL/min。此条件下，所制备的纳米CaCO₃样品为纯相介稳态球霰石晶型，粒度均匀、分散性较好、平均粒径约45nm、平均晶粒尺寸20nm。通过对样品的X-射线衍射（XRD）、扫描电子显微镜（SEM）、和傅里叶红外光谱（FTIR）等表征，对反应温度、CO₂流率的变化对样品粒径的可能影响机制进行了分析，并对复合添加剂影响样品粒径的可能作用机制进行了探讨。

关键词: 纳米碳酸钙, 团聚, 粒度分布, 合成, 二氧化碳