Abstract Immersion nucleation is the nuclei formation mechanism for wet granulation systems where the liquid drops are large relative to the primary particles. The process of immersion nucleation has been examined in many studies, however the kinetics of nuclei formation are not well understood, and there is a distinct lack of experimentally validated models for this process. A kinetic model has been proposed by Hounslow et al. (2009) which describes surface tension driven immersion nucleation. This paper presents the results from a series of experiments measuring the kinetics of immersion nucleation, and these results are compared with the model predictions. Drops of model liquids (aqueous HPMC solution and silicone oil) are placed on static powder beds of zeolite and lactose. Nuclei granules are carefully excavated at different times and the change in granule mass with time is measured. As predicted by Hounslow et al.'s model, the granule mass increases with the square root of time to a maximum granule size at a time tmax after an initial adjustment period. The critical packing factor is shown to be a function of powder properties, and not dependent on the liquid properties. The model captures well the measured effects of liquid and powder properties. However, the kinetics of the nucleation process are much slower than predicted by the model. It is believed this is due to continued percolation of the liquid within the powder bed, after the liquid drop is fully immersed. This secondary liquid movement may have an important effect on granule growth kinetics, and influence final granule product properties.

中文翻译：

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表面张力驱动的浸入式成核动力学

摘要 浸入成核是湿法制粒系统的成核机制，其中液滴相对于初级颗粒较大。浸入成核的过程已经在许多研究中得到检验，但是成核的动力学还没有得到很好的理解，并且明显缺乏这个过程的实验验证模型。Hounslow 等人提出了一个动力学模型。(2009) 描述了表面张力驱动的浸入成核。本文介绍了一系列测量浸入式成核动力学的实验结果，并将这些结果与模型预测进行了比较。模型液体（HPMC 水溶液和硅油）滴在沸石和乳糖的静态粉末床上。在不同时间仔细挖掘细胞核颗粒，并测量颗粒质量随时间的变化。正如 Hounslow 等人的模型所预测的那样，颗粒质量随着时间的平方根增加，在初始调整期后的时间 tmax 处达到最大颗粒尺寸。显示临界填充因子是粉末特性的函数，而不依赖于液体特性。该模型很好地捕捉了液体和粉末特性的测量效果。然而，成核过程的动力学比模型预测的要慢得多。据信这是由于在液滴完全浸没之后液体在粉末床内的持续渗透。这种二次液体运动可能对颗粒生长动力学产生重要影响，并影响最终颗粒产品的特性。