(中国科学院 过程工程研究所 绿色过程工程实验室，北京 100080)
摘 要: 提出一种新的反应结晶过程，即采用Na2CO3溶液为沉淀剂，选择合适条件与MgCl2溶液进行均相(不加晶种)结晶反应，实现从卤水中沉淀镁，制得MgCO3·3H2O晶体。研究温度、反应液初始浓度及滴加速率对MgCO3·3H2O晶体生长及晶形的影响，采用XRD和SEM对得到的晶体进行表征。结果表明：MgCO3·3H2O晶体的收率为98.1%，纯度为99.9%，所得到的晶体为MgCO3·3H2O，且温度、反应液初始浓度及滴加速率对MgCO3·3H2O晶体的生长、形态及颗粒大小都有着显著的影响。
关键字: MgCO3·3H2O；晶体生长；沉淀剂
（Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences,
Beijing 100080, China）
Abstract:MgCO3·3H2O was selected as target precipitate in extraction of magnesium from brine due to its good filtration properties and its excellent dewatering characteristics. A novel homogeneous (unseeded) precipitation of MgCO3·3H2O by the reaction of MgCl2 with Na2CO3 in supersaturated solutions was investigated for the precipitation of magnesium from brine. The factors influenced the crystal growth and morphology of MgCO3·3H2O, such as reaction temperature, initial concentration and titration speed were studied. The results show that the yield of MgCO3·3H2O is 98.1% and the purity of MgCO3·3H2O is 99.91%. MgCO3∙3H2O as prepared were characterized by X-ray diffraction(XRD) and scanning electron microscope(SEM). The results show that the product is club-shaped MgCO3·3H2O and the temperature, initial concentration and titration speed all have significant effect on the crystal growth, crystal morphology and particle size distribution.
Key words: MgCO3·3H2O; crystal growth; precipitate
