Controlled Supersaturation Precipitation of Hydromagnesite for the MgCl2−Na2CO3 System at Elevated Temperatures: Chemical Modeling and Experiment
Controlled Supersaturation Precipitation of Hydromagnesite for the MgCl2−Na2CO3 System at Elevated Temperatures: Chemical Modeling and Experiment
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DOI：
10.1021/ie9015073
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发表时间：
2010-01
影响因子：
4.2
通讯作者：
Wenting Cheng-;Zhibao Li
中科院分区：
文献类型：
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作者：
Wenting Cheng-;Zhibao Li
提出了一个新的过饱和度（S）化学模型，并应用于MgCl_2-Na_2CO_3体系在50-90 ℃过饱和溶液中水菱镁矿[Mg-5（CO_3）（4）（OH）（2）中心点4H（2）O]的沉淀实验。在此基础上，借助OLI平台，通过计算不稳定溶液中各物种的活度系数，精确地构建了Mg-5（CO3）（4）（OH）（2）中心点4H（2）O的等值线过饱和度.通过X射线衍射（XRD）和扫描电子显微镜（SEM）表征了Mg-5（CO3）（4）（OH）（2）中心点4H（2）O晶体。结果发现，可以通过控制沉淀过程中的过饱和度来优化晶体性质，如形貌、粒度分布、过滤和沉降特性。通过控制过饱和度，可生长出平均粒径为30-40 μ m的球形Mg-5（CO 3）（4）（OH）（2）中心点4H（2）O晶体，表明其粒度分布窄，过滤性能好，沉降速度快。另外，将得到的Mg-5（CO3）（4）（OH）（2）中心点4H（2）O在800 ℃下煅烧，制造高纯度MgO。MgO的尺寸和形貌与相应前驱体的相同特征相似。
A new chemical model of supersaturation (S) was developed and applied to test for the precipitation of hydromagnesite [Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O] in the MgCl2-Na2CO3 system in supersaturated solutions over the temperature range of 50-90 degrees C. Based on the new model with the help of the OLI platform, the contour supersaturation of Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O has been exactly constructed by calculating the activity coefficients of species in unstable solutions. Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O crystals were identified using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) images. It was found that the crystal properties, such as morphology, particle size distribution, filtration, and sedimentation characteristics, can be optimized by controlling the supersaturation during precipitation. With the control of supersaturation, well-developed spherical-like Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O crystals can grow to an average size of 30-40 mu m, indicating a narrow particle size distribution, good filtration characteristics, and a high sedimentation rate. In addition, the Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O obtained was calcined to produce high-purity MgO at 800 degrees C. The size and morphology of MgO were similar to the same characteristics of the corresponding precursors.