Tumbling blenders mechanisms

Materials introduced into the mixing unit (mixer or blender) are shifted in many ways by means of a fluidizing gas (fluidized bed mixer or pneumatic mixer), by mixer rotation (tumble blenders) or by the movement of some internal mixing mechanisms (ribbon, Z-blades, etc.) of the mixer (mechanical mixer). 

Dry blending of powdery TPO is carried out in tumble blenders or in mechanical blenders. This is the case when incorporating into TPO of stabilizers. 

In the remainder of this section we discuss recent findings regarding the scale-up of tumbling blenders, which have more easily classified flow fields and mixing mechanisms than convective blenders. As mentioned previously, the description of mixing mechanisms in convective blenders has not been the subject of considerable experimental investigation work, relegating scale-up considerations to trial and error. 

At the present time, mechanisms for segregation even in the simple tumbling drum remain obscure, and work on more complex and industrially common blender geometries is extremely limited. Three distinct types of demixing are moderately well characterized in tumblers. They are radial demixing, axial demixing, and competitive patterned demixing. We describe each of these in turn. 

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