The dissolution of solids in slurry stirred tanks is affected from the solid concentration distribution to different extend, depending on the agitation conditions. In this work, the relationship between solid–liquid mixing and mass transfer is investigated by estimating the characteristic times of different phenomena: liquid mixing, solid dissolution, diffusion of the dissolved species in the vessel volume. The analysis is based on Electrical Resistance Tomography data collected during the simultaneous operations of dissolution and mixing. For dilute solid–liquid systems, the relative importance of the solid dissolution and the liquid mixing depends on the particle size and the impeller speed, while the diffusion in stagnant zones is often negligible. Instead, the diffusion mechanism has an important effect on mass transfer for dense systems, where strong axial gradients of solid concentration are established and the stirred tank volume can be divided into a lower zone containing a cloud of dense mixture and an almost stagnant clear liquid layer on top. Based on original and literature experimental data, a method for the main mass transfer resistance identification depending on the agitation condition, the solid volume fraction distribution and the soluble particle size is suggested.

固体在浆液搅拌罐中的溶解受固体浓度分布的影响程度不同，具体取决于搅拌条件。在这项工作中，通过估计不同现象的特征时间来研究固液混合与传质之间的关系：液体混合，固体溶解，溶解物质在容器体积中的扩散。该分析基于在溶解和混合的同时操作中收集的电阻层析成像数据。对于稀的固液系统，固溶和液体混合的相对重要性取决于颗粒大小和叶轮速度，而停滞区的扩散通常可以忽略不计。相反，扩散机制对致密系统的传质有重要影响，在这里建立了很强的固体浓度轴向梯度，并且搅拌釜的容积可以分为下部区域，下部区域包含一团浓密的混合物和顶部几乎停滞的透明液体层。根据原始和文献实验数据，提出了一种根据搅拌条件，固相体积分数分布和可溶性颗粒大小确定主要传质阻力的方法。