Growth Process of Ammonium Sulfate Crystals Produced by Secondary Nucleation in Stirred-Tank Crystallizer

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN

Mitsutaka Kitamura¹  Hiromi Endo¹ 

[1] Department of Chemical Engineering, Faculty of Engineering, Hiroshima University

关键词: Ammonium Sulfate;    Crystallization;    Crystal Growth Rate;    Dissolution Rate;    Nucleation;    Secondary Nucleation;   

DOI  :  10.1252/jcej.24.593

来源: Maruzen Company Ltd

【 摘 要 】

References(15)Cited-By(3)Growth behavior of ammonium sulfate secondary nuclei originated from a seed crystal in a stirred-tank crystallizer was investigated using a Coulter Counter. From the time dependence of the cumulative curves it appeared that the particles can be divided according to growth behavior into two groups. Particles larger than 40 μm grow fast, independently of size (group I), and particles less than 20–30 μm grow at a rate 1–2 orders lower than that of group I (group II). It was also suggested that the secondary nucleation mechanisms of groups I and II are different, and that of group I may be initial breeding. It was observed that for a portion of the group II particles the growth rate increases abruptly during the crystallization. Dissolution rates of group I particles obtained from the cumulative curves were consistent with the values calculated by the mass transfer rates equation, but those of group II were largely lower than the calculated values. The difference in growth behavior between groups I and II was attributed neither to Gibbs–Thomson effect nor to mass transfer rate changes with particle size, but to the difference in the contribution of surface kinetic process. It was found that the growth process of large ammonium sulfate crystals (group I) is much more controlled by volume diffusion than are those of other salts such as potassium sulfate.

【 授权许可】

Unknown