Crystallization and Agglomeration Kinetics of Hydromagnesite in the Reactive System MgCl2-Na2CO3-NaOH-H2O
Crystallization and Agglomeration Kinetics of Hydromagnesite in the Reactive System MgCl2-Na2CO3-NaOH-H2O
复制标题
反应体系MgCl2-Na2CO3-NaOH-H2O中水菱镁矿的结晶和团聚动力学
DOI：
10.1021/ie300213c
复制
发表时间：
2012-06-13
影响因子：
4.2
通讯作者：
Li, Zhibao
中科院分区：
文献类型：
--
作者：
Wang, Junfeng;Li, Zhibao
在连续操作的混合悬浮液混合产物去除（MSMPR）结晶器中首次系统地研究了MgCl 2-Na 2CO 3-NaOH-H2O体系水菱镁矿（4 MgCO（3）中心点Mg（OH）（2）中心点4 H（2）O）的反应结晶动力学。通过间歇结晶实验确定了反应温度和OH-离子对上述体系中碳酸镁水合物的影响，并选择80 ℃的结晶温度进行了动力学研究，得到了规则球状水菱镁矿的析出。根据Pitzer模型计算出的活度系数，得到了水菱镁矿的相对过饱和度。根据团聚粒子数平衡方程确定了生长速率、成核速率和团聚核，并将其动力学方程用幂律动力学表达式关联起来。体积增长率和线性增长率相对于相对过饱和度的量级分别为1.55和0.95。岩浆密度对水菱镁矿颗粒的成核速率有重要影响。而水菱镁矿聚集体的β α M-T（-0.39）表达式表明岩浆密度对聚集核有负影响。为工业结晶器的设计和分析提供了依据。
The reactive crystallization kinetics of hydromagnesite (4MgCO(3)center dot Mg(OH)(2)center dot 4H(2)O) for the MgCl2-Na2CO3-NaOH-H2O system has been systematically investigated in a continuously operated mixed-suspension mixed-product removal (MSMPR) crystallizer for the first time. Determination of the effects of reactive temperature and OH- ion on magnesium carbonate hydrates in the above system was conducted through a batch crystallization experiment, and the crystallization temperature of 80 degrees C for the precipitation of regular spherical-like hydromagnesite was selected for the kinetics study. The relative supersaturation for hydromagnesite is obtained based on the activity coefficients calculated by the Pitzer model. The growth rate, nucleation rate, and agglomeration kernel are determined on the basis of the agglomeration population balance equation, and their kinetic equations are then correlated in terms of power law kinetic expressions. The orders of volume growth rate and linear growth rate with respect to the relative supersaturation are 1.55 and 0.95, respectively. The magma density has an important effect on the nucleation rate of hydromagnesite particles. However, the expression of beta alpha M-T(-0.39) for hydromagnesite agglomeration shows that the magma density has a negative effect on the agglomeration kernel. All of these will provide a basis for the design and analysis of industrial crystallizers.