Continuous agitation

A blending system provides the kiln with a homogeneous raw feed. In the wet process the mill slurry is blended in a series of continuously agitated tanks in which the composition, usually the CaO content, is adjusted as required. These tanks may also serve as kiln feed tanks, or the slurry after agitation is pumped to large kiln feed basins. Dry-process blending is usually accompHshed in a silo with compressed air. 

Some of the devices covered here handle the solids burden in a static or laminar-flowing bed. Other devices can be considered as continuously agitated kettles in their heat-transfer aspect. For the latter, unit-area performance rates are higher. 

To produce a moulding composition, aniline is first treated with hydrochloric acid to produce water-soluble aniline hydrochloride. The aniline hydrochloride solution is then run into a large wooden vat and formaldehyde solution is run in at a slow but uniform rate, the whole mix being subject to continuous agitation. Reaction occurs immediately to give a deep orange-red product. The resin is still a water-soluble material and so it is fed into a 10% caustic soda solution to react with the hydrochloride, thus releasing the resin as a creamy yellow slurry. The slurry is washed with a counter-current of fresh water, dried and ball-milled. 

The mixture is heated at reflux for two hours with continual agitation and there is then added dropwise a solution of 2-methyl-3-dimethylaminopropyl chloride in an equal volume of Xylene. The mixture is then heated for fifteen hours, after which time it is cooled and decomposed by the cautious addition of ice water. The layers are separated and the aqueous layer extracted with ether. The combined organic layers are next extracted with 10% hydrochloric acid and the acidic extracts then rendered alkaline by the addition of ammonium hydroxide. The precipitated oil is extracted three times with chloroform. The chloroform extracts are dried and concentrated in vacuo, the residue being distiiled to yield the product. 

An autoclave (Note 1) is charged with 200 g. (1.28 moles) of 2,3-dimethylnaphthalene (Note 2), 940 g. (3.14 moles, 23% excess) of sodium dichromate dihydrate, and 1.8 1. of water. The autoclave is closed, heated to 250°, and shaken continuously at this temperature for 18 hours. The autoclave is cooled with continued agitation (Note 3), the pressure is released, and the autoclave is opened. The contents are transferred to a large vessel (Note 4). To effect complete transfer, the autoclave is rinsed with several 500-ml. portions of hot water. Green hydrated chromium oxide in the reaction mixture is separated on a large Buchner funnel and washed with warm water until the filtrate is colorless. The combined filtrates (7-8 1.) are acidified with 1.3 1. of 6N hydrochloric acid. The acidified mixture is allowed to... 

The USP disintegration test is typical of most and is described in detail in a monograph of that volume. Briefly, it consists of an apparatus in which a tablet can be introduced into each of six cylindrical tubes, the lower end of which is covered by a 0.025 in.2 wire mesh. The tubes are then raised and lowered through a distance of 5.3-5.7 cm at a rate of29-32 strokes per minute in a test fluid maintained at 37 2°C. Continuous agitation of the tablets is ensured by this stroking mechanism and by the presence of a specially designed plastic disk, which is free to move up and down in the tubes. 

Catalyst Y-G was prepared in conformity with the spray-drying method of Yates and Garland 27). Ni(N03)2 was dissolved in a small amount of distilled water, whereupon acetone and the requisite amount of aerosil were successively added to it. The slurry was transferred to an atomizer and sprayed with continuous agitation. The spray was directed to a glass surface and the particles adhering to this surface were dried by leading a stream of air over them. 

Hydroxy-3-naphthoic acid ( BONA or BON ) is prepared by heating the sodium salt of 2-hydroxynaphthalene with carbon dioxide in a pressure chamber at 240 to 250°C at a pressure of 15 bar (Kolbe synthesis). The reaction mixture is continuously agitated. Remaining 2-naphthol is separated and recycled ... 

It is essential that the contents of the flask be continually agitated by vigorous shaking in order that the heavy dust may remain in contact with the organic substance. 

J. Alvarez, J. Alvarez, and R. Suarez. Nonlinear bounded control for a class of continuous agitated tank reactors. Chem. Eng. Set., 46(12) 3341-3354, 1991. 

Diffusion studies were performed by using a Valia-Chen diffusion cell (Crown Glass Co., Inc., Somerville, NJ). The apparatus consisted of two half-cells, receptor cell and donor cell, with a volume of 3 mL and a side opening with a diameter of 9 mm. A magnetic stir bar was placed in each half-cell for continued agitation. Between the two half-cells a preswollen membrane was securely placed and was protected from the atmosphere to prevent evaporation of the solvent form the membrane. 

Polymers may be made by four different experimental techniques bulk, solution, suspension, and emulsion processes. They are somewhat self-explanatory. In bulk polymerization only the monomers and a small amount of catalyst is present. No separation processes are necessary and the only impurity in the final product is monomer. But heat transfer is a problem as the polymer becomes viscous. In solution polymerization the solvent dissipates the heat better, but it must be removed later and care must be used in choosing the proper solvent so it does not act as a chain transfer agent. In suspension polymerization the monomer and catalyst are suspended as droplets in a continuous phase such as water by continuous agitation. Finally, emulsion polymerization uses an emulsifying agent such as soap, which forms micelles where the polymerization takes place. 

First, 400 kg of finely divided salt with a water content of about 8 % by mass is to be dried in the shortest possible time (about 1 h) until the water content is less than 1 % by mass. The expected water evolution amounts to about 28 kg. The salt in the chamber is continuously agitated during the drying process and heated to about 80 °C. The vacuum system is schematically drawn in Fig. 2.78. 

Glassy Sb Sci alloys (x < 0.05) were prepared by conventional melt quenching. Cleaned silica tubes containing a mixture of the appropriate amount of constituents Sb and Se were evacuated to lO Torr and sealed. The contents of the tubes were melted in a furnace and continuously agitated for 10 h to ensure good homogeneity. The melt was rapidly quenched in cold water from 800 K, and the cooling rate was estimated to be 200 K/s. 

Two hundred and sixty-seven grams (296 ml., 4.38 moles) of 28% aqueous ammonium hydroxide, 207.5 g. (209 ml., 1.57 moles) of paraldehyde, and 5.0 g. (0.065 mole) of ammonium acetate are heated to 230° with continuous agitation in a 2-1. steel reaction vessel (Note 1), and the temperature is maintained at 230° for 1 liour (Note 2). The autoclave is then allowed to cool, and the two layers of the reaction mixture are separated (Note 3). To (lie non-aqueous layer is added 60 ml. of chloroform, causing separation of water which is combined with the aqueous layer. I he aqueous layer is extracted with three 50-ml. portions of chloroform, and the extracts are combined with the main portion of the chloroform solution. After removal of the chloroform by distillation at atmosiiheric pressure, fractional distillation under reduced pressure through a 30-cm. Fenske-type column gives a fore-run of water, paraldehyde, and a-picoline, b.p. 40-60°/17... 

Pass trimethoprim/sulfamethoxazole mass from step 4 and balance of sulfamethoxazole through a 595-micron-aperture screen in Fitzmill knives forward, medium speed, and slowly add to main tank with continuous agitation. 

Heat if necessary. Add glycerine, continue agitation, and cool to room temperature. Add filtrate from step above to cooled syrup. 

Because the specific weight of sulfur is about twice that of the asphalt, the solid sulfur particles will settle out unless the blend is continually agitated. 

Into a flask containing 220 o.c. of 30 per cent, aqua ammonia cooled by a freezing mixture, slowly run 75 c.c. of bromine from a dropping funnel with its stem drawn out to a fine point. The liquid should be continuously agitated when the ammonia is being added, and it should also remain strongly ammoniacal when all the bromine has been introduced. Warm the mixture to drive off the excess of ammonia, and evaporate until the liquid crystallizes. The crystals are dried in a porcelain dish over a hot plate. About 220 grms. of the required salt can be so obtained. 

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