Mixer blades

Mechanical means for controlled circulation of the solids slurry must be provided with at least a 3 1 range of speeds. The maximum peripheral speed of mixer blades should not exceed 6 ft/sec. 

Fig. 2 Shearing path of mixer blades through wet mass at capillary state. (From Ref John Wiley and Sons, Inc.)...

In the literature, there are various equipment parameters used as guides during scale-up of wet granulation processes in high-shear mixers. The first one that is commonly used is the tip speed of the mixer blade. This can be calculated as shown in Eq. (1). 

Because the materials most commonly mixed in kneaders are very viscous, often elastic or rubbery materials, a large amount of energy must be applied to the mixer blades. All that energy is converted to heat within the material. Often the material begins as a semisolid mass, with liquid or powder additives, and the blending process both combines the materials and heats them to create uniform bulk properties. 

Rubber premixes made using bale rubber are processed in high-intensity Banbury mixers that are widely used in the rubber processing industry. The mixer uses two heavy-duty counterrotating mixer blades to intimately mix fillers and fibers into the rubber. The product of Banbury mixers are either directly formed in a cure press or used as an ingredient in a friction formulation after size reduction. 

Abrasion of talc is so low that it is compared with that of wood flour. For example, abrasion on a brass mixer blade, operating at 2000 rpm for 1.5 h, was practically undetecteable in a study in which talc (Silverline 002, see Table 4.8), wood flour, and polyethylene were employed. It was also undetectable even when the volumetric loading of talc was three times that of the wood flour but was quite noticeable with rice hulls containing silica [8]. 

A variation of the stirred bed design involves a horizontal stirred drum, filled to two-thirds depth with substrate, with introduction of air through a perforated central shaft embedded in the substrate bed and upon which mixer blades are mounted (Fig. 10). This bioreactor has been successfully used for... 

Construction one part augers, several individual augers, augers with replaceable rims, larger diameter at transition from mixer blades to augers... 

With mechanically agitated countercurrent extractors, energy is induced by rotating internals. Agitators are usually mounted on a central column shaft at certain distances from each other (double blade mixer, disc mixer, blade mixer, turbine mixer, helical screw mixers, etc.). Installation of stators (ring discs, punched metal sheets. 

A very useful reactor assembly for pilot-scale polymerization of lactide and glycolide polymers and copolymers is an 8-CV mixer from Design Integrated Technologies (DIT) of Warrington, Virginia. The 8-CV is a dual cone mixer (8 qt. capacity) equipped with double helical mixer blades, a gas inlet line, and a large vacuum port. 

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