Evaluating Resonant\nAcoustic Mixing as a Wet Granulation\nProcess

Control of powder properties is crucial for industrial\nprocesses\nacross the food, pharmaceutical, agriculture, and mineral processing\nindustries, and granulation is an important tool for providing agglomerated\nparticles with controllable properties. However, existing granulation\nprocesses are not readily integrated with other processing steps and\nare not appropriate for some types of materials. Adding resonant acoustic-based\ngranulation to the toolkit has the potential to widen the achievable\nparameter space and, importantly, integrate granulation into chemistry\nand blending operations that are already being performed on the RAM\nplatform, resulting in process intensification. Here, we demonstrate\nthe formation of granules with particle sizes of ca. 1–3 mm\nin LabRAM II and examine the formation mechanisms in the context of\ncommon wet granulation processes. The RAM granulation process followed\nhere involves first forming a large “doughball” agglomerate\nand then driving its breakup by evaporating the solvent, while impacting\nthe doughball against the container walls. We show that this process\nis similar to the destructive nucleation model for high-shear wet\ngranulation with the solvent evaporation in our case leading to the\ndecrease in the liquid saturation of the doughball, a corresponding\ndecrease in its tensile strength, and the acceleration in the RAM\nestablishing the impact pressure when the doughball contacts the walls.\nThis work provides a foundation for granulation process design with\na resonant acoustic mixer and, through its link to existing granulation\nmechanisms, provides a path to a deeper understanding of the process.