Abstract:

The high-gravity reaction crystallization method has the advantages of intensifying mass transporting function and the grain sizes of the product are distributed within a narrow range in the preparation of calcium carbonate. Spherical calcium carbonate with uniform size distribution and regular morphology was successfully prepared by using high concentration calcium hydroxide slurry as raw material, ammonium chloride and L-glutamic acid as additives in a high-gravity reactor. The effects of various factors on the preparation of spherical calcium carbonate by high-gravity reactive crystallization were studied and the optimal preparation conditions of spherical calcium carbonate were also investigated by changing the amount of additives and the high-gravity factor. The product of calcium carbonate was analyzed by SEM, XRD, FTIR and static particle image analysis, and the influence of additives on calcium carbonate in the whole reaction process was explored by sampling test. The test results indicated that the prepared product was spherical calcium carbonate with a particle size of about 500nm and a crystal form of vaterite. At the same time, it showed that the spherical calcium carbonate had the most regular morphology when L-glutamic acid and ammonium chloride were 4% and 20% of the mass of calcium hydroxide, respectively, and the high gravity factor was 161.0.

Key words: high-gravity reaction, spherical calcium carbonate, vaterite, L-glutamic acid, ammonium chloride

摘要：

超重力反应结晶法在碳酸钙制备中具有强化传质作用、产品粒度分布窄等优点。本文以高浓度氢氧化钙浆液作为原料，氯化铵与L-谷氨酸为添加剂，使用超重力反应器成功制备粒径分布较为均匀、形貌较为规整的球形碳酸钙。探究了各因素在超重力反应结晶法制备碳酸钙中的影响，通过改变添加剂的量与超重力因子等考察球形碳酸钙的最佳制备条件。采用扫描电子显微镜（SEM）、X射线衍射（XRD）、傅里叶变换红外光谱仪（FTIR）和静态颗粒图像分析等测试手段对碳酸钙产物进行分析，并通过在反应过程中抽样测试的方法探究反应全过程中添加剂对碳酸钙的影响。结果表明，所制备的碳酸钙为粒径约500nm、晶型为球霰石的球形碳酸钙，同时在L-谷氨酸和氯化铵添加量分别为氢氧化钙质量的4%与20%、超重力因子为161.0的条件下所制备的球形碳酸钙形貌最为规整。

关键词: 超重力反应, 球形碳酸钙, 球霰石, L-谷氨酸, 氯化铵