Editing Mixing (process engineering) (section)

===Mixing mechanisms===
In powder two different dimensions in the mixing process can be determined: convective mixing and intensive mixing.<ref>{{cite web|url=http://www.powderprocess.net/Mixing.html|title=Powder Mixing - Design - problem solving - Ribbon blender, Paddle mixer, Drum blender, Froude Number - PowderProcess.net|website=www.powderprocess.net|access-date=26 April 2018|url-status=live|archive-url=https://web.archive.org/web/20170928143738/http://www.powderprocess.net/Mixing.html|archive-date=28 September 2017|df=dmy-all}}</ref> In the case of convective mixing material in the mixer is transported from one location to another. This type of mixing leads to a less ordered state inside the mixer, the components that must be mixed are distributed over the other components. With progressing time the mixture becomes more randomly ordered. After a certain mixing time the ultimate random state is reached. Usually this type of mixing is applied for free-flowing and coarse materials.

Possible threats during macro mixing is the de-mixing of the components, since differences in size, shape or density of the different particles can lead to segregation.
 
When materials are cohesive, which is the case with e.g. fine particles and also with wet material, convective mixing is no longer sufficient to obtain a randomly ordered mixture. The relative strong inter-particle forces form lumps, which are not broken up by the mild transportation forces in the convective mixer. To decrease the lump size additional forces are necessary; i.e. more energy intensive mixing is required. These additional forces can either be impact forces or shear forces.