Mixing of Solids

摘要

Mixing of solids is a widespread and important unit operation in food processing. Some mixes are products themselves, while others are preliminary steps in more complex processes. ___ Historically, mixing of solids has been studied empirically because there seemed to be little fundamental understanding. However, this has changed relatively recently, as physicists and engineering researchers have recognized the importance of solids behavior and the intellectual challenge and satisfaction of solving problems in this area. Some time spent reading research papers from these areas can provide significant insight. In contrast to liquids and gases, granular solids or powders can segregate or become unmixed under a variety of influences. If particles differ in size or density (they often differ in both), almost any motion will cause some difference in individual velocities in the assembly. The result is segregation, having the practical consequence of varying composition, when a uniform mixture is usually desired.