Mixing Muller mixer

The muller is useful for mixing problems requiring certain types of aggregate breakdown, fricdional anchorage of particles to one another, and densification of the final mix. Materials which are excessively fluid or sticky should be avoided. The muller mixer is generally used for batch operations (Fig. 19-9g), although Fig. 19-9/j shows a continuous muller. 

Mullers can be used if the paste is not too fluid or sticky. The main application of muller mixers is now in the foundry industry to mix small amounts of moisture and binder with sand for both core and molding sand. Muller mixers also handle such diverse materials as... 

Fig. 5 Mix muller-type mixer. (Courtesy of Sud-Chemie Inc.) (View this art in color at www.dekker.com.)...

Example 28.2. A ty soil containing 14 percent moisture was mixed in a large muller mixer with 10.00 weight percent of a tracer consisting of dextrose and picric acid. After 3 min of mixing, 12 random samples were taken from the mix and analyzed colorimetrically for tracer material. The measured concentrations in the sample were. 

Since gases (air) in the bulk feed must be totally removed to avoid compressed air pockets, blending prior to agglomeration should not be carried out in high speed powder mixers. A good piece of equipment for this task is the batch or continuous mix-muller (Fig. 11.31). 

During normal operation fresh pre-mixed (if applicable) feed (2) and recyclate (18) are proportioned by rotary gates and weigh belts (3). The ratio of fresh feed to recyclate should be kept constant it is only adjusted if the level controls in bins (2) and (18) require modification of compactor feed composition. Typically a changed relationship fresh feed to recyclate necessitates readjustment of the compactor (8) and, sometimes, the oversize crusher (16) parameters. Fresh feed and recyclate are homogenized in a low-intensity mixer (e.g.,. pug mill, mix muller) (4) and transported by buck-... 

Muller Mixer. A wet pan (q.v.) in which the mullers are suspended out of contact with the pan bottom. Thus the material charged to the pan is mixed without further grinding taking place. Mullet. A knife-shaped piece of iron used in severing a handmade glass bottle from the blow-pipe. 

Muller W, Rumpf H. Mixing of powders in mixers with axial motion (in German). Chem Ing Tech 1967 39 365-373. 

Pan mullers are the modern industrial equivalent of the traditional mortar and pestle. Typical mullers have two broad wheels (Ml and M2) on an axle (Fig. 18-54). The mixer rotates about the approximate midpoint of the axle, so that the wheels both rotate and skid over the bottom of the mixing chamber (A). Plow blades (PI and P2), which rotate with the mixer, push material from the center (T) and walls (C) of the mixing chamber into the path of the rollers. The mixing action combines both crushing and shearing to break lumps or agglomerates and evenly distribute moisture. 

FIG. 21-49 Classification of bunker or silo mixers following Muller [W. Muller, Methoden und derzeitiger Kenntnisstand fur Auslegungen beim Mischen von Feststoffen [Methods and the current state of the art in solids mixing configurations], Chem. Eng., 53. 831-844 (1981)]. 

Table VIII, which is a combination of two of Smith s tables, shows the necessity for choosing the proper mixer for the particular soil to be mixed for example, although the two-arm kneader and muller mixed very well with sand, they did not do well with the Marshall clay. The reciprocating conveyor, however, while it did not mix sand too well, did the best job on Marshall clay.

The mixers described in this section are change-can mixers, kneaders, dispersers, and masticators continuous kneaders mixer-extruders mixing rolls mullers and pan mixers and pugmills. 

---