Mixing Mechanics: Improving blend uniformity by controlling particle size
One of the biggest causes of nonuniform powder blends is a wide difference in the ingredients' particle size distribution. If the ingredients' particle sizes are widely distributed, the particles can segregate regardless of your mixer type. It happens with rotating shell units, such as V-blenders and double-cone mixers, and stationary shell units, such as ribbon and plow blenders. When a blend's particles have uniform size or a very narrow size range, segregation is rarely an issue. In this column I'll explore the segregation that takes place both in the mixer and during or following discharge and how you can prevent it.
When segregation occurs
As a general rule, you're more likely to run into segregation problems if your powder blend is free-flowing. If your powder blend flows with difficulty, then it probably won't segregate. This is because the cohesive forces that make the blend balky hold the particles together, preventing segregation...