Paddle-mixer

Sohd—sohd blending can be accompHshed by a number of techniques. Some of the most common iaclude mechanical agitatioa which iacludes devices such as ribboa Headers, impellers, paddle mixers, orbiting screws, etc a rotary fixed container which iacludes twia-sheU (Vee) and double-cone blenders and fluidization, ia which air is used to Head some fine powders. 

Any type of sohds conveyor may be suitable for recycle mixing however, the most universally applicable is the double-shaft pug-miU-type paddle mixer. This conveyor or mixer should be insulated to prevent excessive heat losses from the hot, dry recycle product. To ensure uniformity in the recycle operation, a surge storage reserve of recycle sohds should be installed for startup purposes and in the event of interruption of product discharge from the cyhnder. In recycle operations, 50 to 60 percent product recirculation is found economical in many instances. 

Figure 12-96 illustrates a single-stage dryer employing a paddle mixer, recycle, and an ABB Raymond cage mill for tine grinding and... 

With hafQes Horizontal drum Double cone revolving around long axis Twin shell Ciihe Twin rotor Tiirhine Paddle mixer Sifter (tiirhosifter) Attrition mill Elevator loading Pneumatic conveying Vibrating... 

Figure 7. Tangential flow pattern generated by a paddle mixer.

Propeller/paddle mixers are used to blend or agitate liquid mixtures in tanks, pipelines, or vessels. Figure 38.1 illustrates a typical top-entering propeller/paddle mixer. This unit consists of an electric motor, a mounting bracket, an extended shaft, and one or more impeller(s) or pro-peller(s). Materials of construction range from bronze to stainless steel, which are selected based on the particular requirements of the application. 

The propeller/paddle mixer is also available in a sideentering configuration, which is shown in Figure 38.2. This configuration is typically used to agitate liquids... 

Add wood furnish (384 g, moisture content 6.02%) to the bowl of a rotary blade paddle mixer (such as a Kitchen-Aid KSM90) and agitate at the lowest speed setting. Add Mondur 541 (7.39 g, 1.9% w/w, a polymeric diphenylmethane diisocyanate of 31.5% NCO, Bayer) dropwise over a 5-min period using a disposable syringe. Continue blending for an additional 10 min and then transfer the blend to an 8 x 8 x 2 -in. metal form at the bottom of which is a metal plate which fits inside. The resin-coated furnish is evenly spread inside the form and another metal plate is placed on top. All parts of the form and plates are presprayed with mold release. The completed form assembly is placed into a hydraulic press (such as a model PW-22 manufactured by Pasadena Hydraulics) with platens heated at 350°F. The furnish is then pressed between the two form plates to a thickness of j in. Press controls are used to ensure consistency of board thickness. The assembly is heated for 4 min. before demolding the cured wood panel. 

Fig. 111. A double-motion paddle mixer for premixing Thiokol propellant (Thiokol Chemical Corporation, Redstone Arsenal, according to Warren [5J).

A premix is prepared by mixing the fuel binder (i.e. a polysulphide rubber in the case of the Thiokol propellant) with the necessary curing agents, inert additives, and ballistic modifiers in a double-acting paddle mixer. This mixer is equipped... 

A more intensive mixing-granulating action than that provided by conventional paddle mixers is obtained in shaft mixers operating at high rotational velocities. These machines are generally single-shaft devices in which the paddles are replaced by a series of pins, pegs or blades. They may be operated... 

Paddle mixers, see Pugmills Pan agglomerators, see Disc agglomerators Peg granulator, see High speed shaft mixers... 

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