Agglomerator batch

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. 

If a batch ingredient is in agglomerate form, some device to break up the agglomerates should be used to prevent them from segregating... 

Fluidized beds 0.1 to 2 Low (agglomerated) 100-900 kg batch to scale, difficult for inorganic salts. 

In all such laboratory studies, plant conditions and compositions should be employed as far as possible. Agglomeration rates tend to increase with the level of supersaturation, suspension density and particle size (each of which will, of course, be related but the effects may exhibit maxima). Thus, agglomeration may often be reduced by operation at low levels of supersaturation e.g. by controlled operation of a batch crystallization or precipitation, and the prudent use of seeding. Agglomeration is generally more predominant in precipitation in which supersaturation levels are often very high rather than in crystallization in which the supersaturation levels are comparatively low. 

The product crystals were agglomerates of needles or dendrites. Loose floes of dendroid strontium carbonate are compacted by agitation, which is an important factor in controlling the habit of product particles. Semi-batch operation produces larger particles compared to batch or continuous operation. 

In a study of crystal precipitation of calcium carbonate during the batch carbon-ation of lime water, individual crystals and agglomerated particles were observed as shown in Figure 8.18(a), (b) and (c), respectively (Wachi and Jones, 1991b). 

Sohnel, O., Mullin, J.W. and Jones, A.G., 1988. Nucleation, growth and agglomeration during the batch precipitation of strontium molybdate. Industrial and Engineering Chemistry Research, 27, 1721-1728. 

Hatifchen, n. little heap little mass, clump. Haufe, Haufen, m. heap pile great amount or number, mass (Brewing) couch, piece, floor, batch agglomeration, clump, cluster. hMufen, v.t. heap pile accumulate, amas — v.r. increase. 

Suspension Polymerization. Water is the suspending phase. Inorganic salts and vigorous agitation prevent coalescence and agglomeration. The reaction mode is batch. The largest use of suspension polymerization is for the manufacture of expandable polystyrene beads. 

In the early days of the rubber industry all mixing was carried out on two-roll mills. Now this situation only occurs occasionally, or when small or expensive batches of material are required, e.g., silicones or fluorocarbons. Mill mixing is an efficient method for breaking down agglomerates and, over a period of time, with good operatives, good homogeneity can be achieved. One batch, however, can take some 30-40 minutes to mix. 

As discussed in Chapter 15, the size distribution of particles in an agglomeration process is essentially determined by a population balance that depends on the kinetics of the various processes taking place simultaneously, some of which result in particle growth and some in particle degradation. In a batch process, an equilibrium condition will eventually be established with the net rates of formation and destruction of particles of each size reaching an equilibrium condition. In a continuous process, there is the additional complication that the residence time distribution of particles of each size has an important influence. 

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