Slurry Smooth

An extension of the filter-driers are the reactor-filter-driers, as illustrated in Fig. 7.2-9 by an apparatus known under trademark name Nutrex" and developed by Rosenmund. Equipment of this kind is still more versatile and operation safer. In one vertical position the device can act as a filter, a granulator, and an apparatus for all operations with filter cakes (i.e. re-slurrying, smoothing, and squeezing). In the reverse position, it can operate as a reactor, extractor, evaporator, crystallizer, drier, etc. There are many other companies offering reactor-filter-driers, e.g. SEN, Giovanola, Schenk, and Cogeim. 

Particulates of fly ash are very fine. Some of the silica in the ash is found in the form of small silica spheres, called cenospheres or extendospheres, which make ash a very flowable material. This property not only makes ash miscible in a CBPC slurry, but it reduces the viscosity of the slurry and makes the slurry smooth, easily pumpable, and pourable. This property is a great advantage with CBPC-based drilling cements (Chapter 15). 

Fig. 5. The effect of ultrasonic irradiation on the surface morphology and particle size ofNi powder. Initial particle diameters (a) before ultrasound were i 160 fim-, (b) after ultrasound, fim. High velocity interparticle coUisions caused by ultrasonic irradiation of slurries are responsible for the smoothing...

S The slurry arms for cake washing and smoothing S The cake discharge mechanism... 

Of the connector tubing and the outlet fitting of the slurry reservoir are the sane as that of the colunn blank. This will ensure a rapid and SMOoth delivery of the slurry into the coluan without subjecting the packing to undue sheer forces. 

This process is used to produce intricate, thin-section parts with great dimensional accuracy, fine detail, and very smooth surfaces. All ferrous and nonferrous alloys can be cast in investment molds. Investment casting begins with expendable wax patterns that are assembled into clusters, then coated with a series of successively coarser ceramic slurries. The assembly is then fired in a furnace to dry and harden the ceramic shell and to melt out the wax, leaving a cavity into which molten metal is poured to form the casting. 

Preparation by reaction of tantalum pentachloride with pure lithium dimethylamide in pentane is unsafe. Initial non-reaction is followed by explosion during manipulation of the slurry. Presence of ether or dimethylamine gives smooth reaction. Stepwise displacement of chlorine, starting with the free amine, is also recommended. 

A coal slurry is found to behave as a power law fluid, with a flow index of 0.3, a specific gravity of 1.5. and an apparent viscosity of 70 cP at a shear rate of 100 s 1. What volumetric flow rate of this fluid would be required to reach turbulent flow in a 1/2 in. ID smooth pipe that is 15 ft long What is the pressure drop in the pipe (in psi) under these conditions ... 

Procedure Take about 15-20 mg of sample in a previously cleaned small agate mortar and powder it thoroughly (about 200 mesh). Add to it 2 drops of purified paraffin (commonly known as Nujol) or any other suitable mulling liquid and continue the trituration until a very smooth paste of uniform consistency is achieved. Now, transfer the slurry to a sodium chloride window, placing it carefully into the cavity made by the spacer. Consequently, place the other window on top and thus assemble the cell. With the help of a clean piece of tissue-paper wipe out the excess paste that has squeezed out from the cell windows. Finally, introduce the cell in the respective cell-compartment. 

The solution is allowed to stand for three days at room temperature, and is then concentrated on the steam bath under reduced pressure (water pump) until spattering makes further evaporation impossible. Two hundred cubic centimeters of water is added to the residue, and the contents of the flask are washed into a small beaker where they are stirred to a smooth slurry. The product is filtered, washed thoroughly on the funnel with cold water, and dried in an oven at 80 90°. The crude material melts at 204-206° and weighs 47-57 g. (80-96 per cent of the theoretical amount). It is purified by recrystallization from 650 cc. of boiling methyl alcohol using 5 g. of decolorizing charcoal. The recrystallized, pale yellow needles of 5-nitroinda-zole melt at 208-209°. The yield is 42-47 g. (72-80 per cent of... 

The ink , when screen-printing, is a slurry of conductive carbon particles (sometimes in a solution of conductive resin) that flows smoothly when wet and sets quickly without losing definition and shape. Alternatively, conductive silver paint (as above) will perform the same function. 

The reaction mixture is cooled somewhat (Note 5) and filtered through a large Buchner funnel. The manganese dioxide cake is removed from the funnel and stirred to a smooth paste with 1 1. of fresh water. The slurry is filtered, and the washing is repeated. The total filtrate, about 10 1., is evaporated under reduced pressure on the steam bath to a volume of approximately 3 1. (Note 6). The solution is swirled or stirred gently while 550 ml. (6.6 moles) of 36% hydrochloric acid is cautiously added (Note 7). Evaporation under reduced pressure is then continued imtil a moist cake of solid potassium chloride and 2,3-pyrazinedicar-boxylic acid remains in the flask (Note 8). 

The most commonly employed curative for HTPB is TDI which is comparatively more reactive than other curatives except MDI. Due to this, the pot-life of TDI-cured propellant is only 4— 5h. IPDI is another curative which is preferred to TDI mainly on account of its slow reactivity resulting in extended pot-life, that is, 15-18h and low toxicity [91]. It is only recently that a bicurative system consisting of TDI and IPDI (70 30) has been developed and compared with TDI and IPDI-based systems. Compared with pot-life of TDI system (4—5h), bicurative system has got 7-8 h pot-life. At the same time, viscosity build-up is less in bicurative system revealing an edge over conventional TDI-based system for smooth processing of a propellant slurry [92]. 

Levigate to make smooth slurry and keep aside for 2.0 hours. 

Disperse item 1 in item 10 in a stainless steel vessel, using stirrer. Make smooth slurry and keep aside for use later. 

Slurry (2) in (1) with intensive agitation, stir the mixture into (3). Add (4) with good agitation, continually until smoothly dispersed. Add (5), (6) and (7) with continuing agitation. Add (8) to adjust pH to 7.2-7.5. 

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