The effect of microwave on the crystallization process of magnesium carbonate from aqueous solutions

• Published in: Powder technology 2018-04, Vol.328, p.358-366
• Main Authors: Guo, Zhichao, Han, Wenxiang, Zhao, Wenli, Li, Liye, Wang, Baodong, Xiao, Yongfeng, Alopaeus, Ville
• Format: Article
• Language: English
• Subjects: Crystallization kinetics; Energy input; Mass transfer; Microwave; Population balance; Reactive crystallization
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2018.01.038

The effect of microwave on reactive crystallization is investigated with magnesium carbonate as the working substance. In the experiments, magnesium carbonate is precipitated by mixing aqueous magnesium sulfate and sodium carbonate solutions in a MSMPR crystallizer located in a microwave reactor. A population balance model along with crystallization kinetics is formulated to assess the influence of microwave energy input on nucleation, growth, agglomeration and breakage during crystallization process. A general high order moment method of classes (HMMC) framework is applied to solve the model numerically. The results show that crystallization kinetics parameters, including the nucleation rate constant (kn), the growth rate constant (kg), the exponent of growth rate (g) and the collision efficiency (Ψag) change significantly due to mass transfer enhancement in microwave field. Meanwhile, the exponent of nucleation (n) and the breakage rate constant (kbr) remain constant or only change slightly. It is further discovered that the crystal suspension attenuates the microwave effect during crystallization process. [Display omitted] •The microwave effect on crystallization kinetics is studied quantitatively.•Microwave has significant effects on nucleation, growth, agglomeration processes.•The breakage rate remains constant or changes only slightly in microwave field.•The mechanisms of the microwave effects on kinetic parameters are discussed.•The crystal suspension affects the microwave effect on crystallization system.