Viscous slurries

With any chemical treatment system, the main task is one of getting the chemical thoroughly mixed with the solids without degrading the floes which are formed. For those slurries that are relatively fluid, the chemical can frequently be added and mixed satisfactorily using a relatively wide spatula. However, for those thick, relatively viscous slurries, a power mixer will be required. In this case, the mixer should be stopped about one second after the last of the flocculant is added. Should this approach be required, it means that a suitably designed addition system must be supplied with the full-scale instaUation in order to do an effective job of flocculation. 

Slurry packing techniques are required for the preparation of efficient columns with rigid particles of less than 20 micrometers in diameter. The same general packing apparatus. Figure 4.8, can be used to pack columns by the balanced-density slurry, liquid slurry, or the viscous slurry techniques. Down-fill slurry packing is the method of choice for small bore columns and packed capillary columns. 

Precipitation polymerization, also called slurry polymerization, is a variety of solution polymerization where the monomer is soluble but the polymer precipitates as a fine flock. The formation of olefin polymers via coordination polymerization occurs by a slurry process. Here, the catalyst is prepared and polymerization is carried out under pressure and at low temperatures, generally less than 100°C. The polymer forms viscous slurries. Care is taken so that the polymer does not cake up on the sides and stirrer. 

Scale-up of IFF processes is usually done by arranging a large number of short devices in parallel. The individual filters should be kept relatively small in axial dimension, helping to avoid the excessive build-up of feed pressure resulting from the pumping of viscous slurries [96]. By arranging TFF membranes in parallel or in series, units can be scaled-up to process thousands of liters of cell culture fluid in a few hours [1]. 

Since it is not likely that the viscous slurries which exhibit Bingham plastic behavior will frequently reach Reynolds numbers appreciably greater than 200,000 it is possible to conclude that Fig. 14 may be used to predict pressure drops accurately under all conditions of interest except in the transition regions. If a problem happens to fall into what may appear to be a transition region, use of Fig. 7 is recommended instead of Fig. 4. 

As previously mentioned, FMs were first fabricated by hybrid extrusion and dip-coating [4-6], Firstly, highly concentrated, viscous slurries are extruded and then dried to form a green fiber. The resulting green fibers are dip-coated... 

More effective for viscous slurries where additional mixing is required. 

For vessels greater than 38 m (10,000 gal), the economic attractiveness of side-entering impellers increases. For vessels larger than 380 m (100,000 gal), units may be as large as 56 kW (75 hp), and two or even three may be installed in one tank. For the suspension of slow-settling particles or the maintenance of uniformity in a viscous slurry of small particles, the diameter and rotational speed of a sideentering agitator must be selected on the basis of model tests or experience with similar operations. 

The size distribution of particles will control the amount of liquid needed to fluidize a given quantity of coal. In general, a fine size distribution will produce a more viscous slurry than a coarse size distribution at the same wt% solids, and the fine particles will produce a more non-Newtonian rheological curve. This can be seen in the laboratory results shown in Fig. 3, which compares a coarse coal slurry to a fine coal slurry. It is clearly seen that the fine slurry is much more viscous, its pseudoplastic character is very pronounced, and its yield value is high, while the coarse coal slurry is clearly a Bingham plastic. ... 

Problem areas Circulating pump (viscous slurries), continuous feed addition Heat-exchange capacity... 

Landel et al. s equation appears to be reasonably good with less viscous suspensions, whereas the Frankel and Acrivos equation seems to fit the data with more viscous slurries and at higher particle concentrations. It is assumed that all of Nolte s data are taken at room temperature. 

Slurry packing is suitable for all types of column for all instances in which the pressure resistance of the column tube is sufficient. The balanced slurry technique, however, needs such high pressure drops in order to obtain reasonable fluid velocities with the rather viscous slurry that in most instances only metal columns can be used. 

The resulting mixture will turn into a thick and viscous slurry. Boil the slurry under reflux for at least 60 minutes with constant mechanical stirring. Now, add a solution of 10 g of NaOH pellets dissolved in 50 ml of water. Continue boiling the pale-yellow solution for a further duration of 90-100 minutes gently. 

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