氯化钙对三水碳酸镁晶体结晶过程的影响

以菱镁矿煅烧所得活性氧化镁为原料，氯化钙为添加剂，采用热分解法制备了MgCO₃·3H₂O晶体，主要研究添加剂种类、氯化钙用量及热解时间对结晶过程的影响，并分析氯化钙的作用机理。借助X射线衍射（XRD）和扫描电镜（SEM）表征产物的物相结构和微观形貌。结果表明，氯化钙用量为5.0 g/L时，获得表面长着球状颗粒、平均长度45 μm、长径比15的棒状MgCO₃·3H₂O晶体。氯化钙对MgCO₃·3H₂O晶体的定向生长无调控作用，主要通过静电吸附的方式参与MgCO₃·3H₂O晶体的结晶过程，其作用下，诱导期延长，成核速率减缓，生长速率增大。 

Influence of Calcium Chloride on Crystallization Process of Nesquehonite Crystals

MgCO₃·3H₂O crystals were prepared by thermal decomposition method with the magnesium solution as precursor, calcium chloride as additives. The influence of types of additives, the amount of calcium chloride and pyrolytic time on the crystallization process was investigated. The mechanism of calcium chloride was further analyzed. The phase structure and morphology of the products was characterized with X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that rod-like MgCO₃·3H₂O crystals with spherical particles on the surface was obtained when the amount of calcium chloride is 5.0 g/L. The average length and aspect ratio of rod-like crystals is 45 μm and 15. The calcium chloride has no regulation to the directional growth of MgCO₃·3H₂O crystals. The calcium chloride takes part in the crystallization of MgCO₃·3H₂O crystals with the electrostatic adsorption. The induction period is prolonged, the nucleation rate decreases and the growth rate increases with the participation of calcium chloride.