Mixer intensive

In the screw conveyor process, solutions of poly(vinyl acetate) and catalyst are mixed in a high intensity mixer and continuously introduced to a screw-type saponification and conveyor system (270). Downstream details are similar to those found in the belt process. 

Disk Pads. Organic and sernimetalHc disks ate produced by somewhat similar processes after the mixes are formed. The mix for organics is prepared in an intensive mixer. The mix for semimetalHcs generally requites a less intensive blender. The mix is then pressed into preforms at room temperature and 28—42 MPa (4—6 kpsi) pressure. These preforms are then hot-pressed at 160—180°C for 5—15 min at 28—55 MPa (4—8 kpsi). Sometimes... 

A successful variation of oil agglomeration was used for removal and dewatering of soot from a 1—3% soflds suspension consisting of <5 — fim particles in refinery process waters (Fig. 8). Heavy oil was added to the dilute slurry and intensely agitated in a multistage mixer. The soot agglomerated with the oil to form 3—5 mm pellets that were easily screened from the water (95). The pellets contained only 5—10% water. The process was modified to recover very fine clean coal, and it produced highly uniform, hard, spherical pellets 1—2 mm in diameter. 

Banbury Mixer Preeminent in the field of high-intensity mixers, with power input up to 6000 kW/m (30 hp/gal), is the Banbury mixer, made by the Farrel Co. (Fig. 18-43). It is used mainly in the plastics and rubber industries. The top of the charge is confined by an air-operated ram cover mounted so that it can be forced down on the charge. The clearance between the rotors and the walls is extremely small, and it is... 

High-Intensity Mixer. Mixers such as that shown in Fig. 18-44 combine a high shear zone with a fluidized vortex mixing action. Blades at the bottom of the vessel scoop the batch upward at peripheral speeds of about 40 m/s (130 ft/s). The high shear stress (to 20,000 s" ) and blade impact easily reduce agglomerates and aid intimate dispersion. Since the energy input is high [200 kW/m (about 8 hp/fE)h even powdery material is heated rapidly. 

FIG. 18-44 High-intensity mixer (a) bottom scraper (h) fluidizing tool (c) horn tool (d) flush-mounted discharge valve. Henschel Mixers America, Inc.)... 

Sometimes a system of mixing and dispersing is composed of one or more batch units providing a feed to a continuous intensive dispersion unit. Another possibihty would be a batch mixer and surge bin which provide a continuous feed to a final dispersion unit. Various combinations of this type with adequate samphng at the proper points may be used when continuous flow would be beneficial provided that certain features could be overcome. 

Decrease impact velocity to reduce fragmentation Lower-formulation density. Decrease hed-agitation intensity (e.g., mixer impeller speed, fluid-hed excess gas velocity, drum rotation speed). Also strongly influenced hy distributor-plate design in fluid-heds, or impeller and chopper design in mixers. 

High-shock grades cannot be proeessed on mills or other intensive mixers without destroying the essential fibrous structure of the filler. In these cases a wet process is used in which the resin is dissolved in a suitable solvent, such as industrial methylated spirits, and blended with the filler and other ingredients in a dough mixer. The resulting wet mix is then laid out on trays and dried in an oven. 

The second path in Fig. 3 outlines the approach to a more robust tape designed by Drew [21]. Here the milled rubber and filler are combined with tackifiers and other additives/stabilizers in an intensive dispersing step, such as a Mogul or Banbury mixer. Next, a phenolic resin or an alternative crosslinker is added and allowed to react with the rubber crosslinker to a point somewhat short of crosslinking. The compounded mixture is then charged to a heavy duty chum and dissolved in a suitable solvent like mineral spirits. To prepare a masking tape. 

For turbine mixers that the width of a baffle should not exceed more than one-twelfth of the tank diameter and, for propeller mixers, no more than one-eighteenth the tank diameter. With side-entering, inclined or off-center propellers, as shown in Figure 13, baffles are not required. Instead, shrouded impellers and diffuser rings may be used to suppress vortex formation. These devices contribute to flow resistance and reduce circulation by creating intense shear and abnormal turbulence... 

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