Blenders high shear mixers

Convection blenders reorient groups of particles in relation to one another as the result of mechanical movement, for example, caused by a paddle or a plow. As a result, circulation patterns result in this type of blenders. Subclasses of convection blenders are typically defined by vessel shape and impeller geometry. Ribbon blenders (Fig. 30), planetary blenders (Figs. 31 and 32), orbiting screw blenders (Fig. 33) are examples of convection blenders. High shear mixers comprise another sub-class of convection blenders that will be discussed separately. 

Tumble blenders also impart shear forces to the powders being blended as slip planes form between the walls of the blender and layers of the blend. The amount of shear force is often low for small-scale blenders, but can increase with increasing scale of the blending container. Because they tend to provide gentler blending and have less of an affect on the particle size of the materials being blended (compared to high shear mixers),... 

Fig. 11.13 Photograph of different tumble/growth agglomeration work modules that are attached to the all purpose drive stand of Fig. 11.12. (a) disc or pan agglomerator (b) coating pan (c) bowl blender (d) planetary bowl blender (e) double cone blender (f) cube mixer (g) high shear mixer (h) pug mill/kneader (courtesy Erweka, Heusenstamm, Germany).

A vertical helical ribbon blender can be combined with an axial screw of smaller diameter (Fig. 18-25). Such mixers are used in polymerization reactions in which uniform blending is required but in which high-shear dispersion is not a factor. Addition of the inner flight contributes little more turnover in mixing newtonian fluids but significantly shortens the mixing time in nonnewtonian systems and adds negligibly to the impeller power [Coyle etal.. Am. Inst Chem. Eng.J., 15, 903 (1970)]. 

High shear blenders Horizontal high intensity mixers (side driven) Vertical high intensity mixers (top or bottom driven)... 

For liquid systems, vinyl dispersions are prepared in both low intensity blender/mixers and high shear agitation systems. The choice depends upon the viscosity of the mix and the ability to control the temperature so that gelation is avoided. Ribbon blenders to high-speed kettle mixers are employed in mixing... 

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