Horizontal mixers

For side entering horizontal mixers not limited to blending operations, there are some differences in recommendations concerning the physical location of the impeller ... 

The horizontal mixers normally used consist of a w shaped mixing bowl with two Z blades (Figure 2). These mixers do not have a removable bowl so the dough has to be tipped out. The mixers can deliver large amounts of energy at low speeds. 

Fig. 8.81 Photographs of two high pressure axial screw extruders showing different die changers. (a) Extruder (model 90AD with horizontal mixer/pug sealer and dual hinged mouthpieces (= dies), (b) extruder (model 90AD with hydraulic horizontal die changer dies are not installed in the die holders (courtesy J.C. Steele, Statesville, NC, USA).

Auger shaft horizontal, mixer shaft vertical. 

FIGURE 32.20 Osmotic dehydrator—a horizontal mixer. (1) feed hopper (2) vessel (3) worm screw (4) deflector (5) discharge hopper (6) shaft. (From Lenart, A. and Lewicki, P.P., Zesz- Nauk. SGGW-AR, Technol. Roln.-Spot, 14, 33, 1981. With permission.)... 

Roberts, F. and Bell, B. T. Horizontal mixer-settler equipment for liquid-liquid extraction. Trans. Inst. Chem. Engineers 35, 6 (1957). 

Mixer operation can provide some process control but not as much as to alter the material. In batch mixers, mixing time and binder addition time can be altered. If an agglomerating mass is more deformable, then the energy input from a mixer can be reduced, for example, by reducing the speed. In horizontal mixers where make-up becomes significant, the speed can often be reduced to reduce agglomeration. 

In vertical mixers, the rotor is installed in a 90° angle to the bottom of the vessel and for horizontal mixers the rotor is parallel to the ground. The cylindrical vessel form is used for horizontal mixers. In case of vertical mixers, it can have a conical or a cylindrical form. 

In rare instances the time of contact must be very short, and for such situations mechanical mixers like those employed in the centrifuge treating systems may be employed. Continuous contacting with acid has also been accomplished by means of a horizontal mixer in which a shaft, equipped with blades, rotates at 900 rpm. 

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