Lumps of powder

However, this type of plate is being replaced in most fluid-bed applications due to its inherent disadvantages, which are caused by the difficulties of punching holes of smaller diameter than the thickness of the plate itself The result is that the plates are weak and are prone to sifting back of the finer particles. The perpendicular flow pattern also means that the plate does not provide a transport capacity for lumps of powder along the plane of the plate. 

Figure 10.27a depicts a heap or lump of powder particles on water. Water should penetrate into it. This is usually aided by stirring, whereby water can penetrate from all sides. If the water does not penetrate fast enough, fairly firm lumps are formed, in which the outside is a gluey layer of partly dissolved or swollen powder particles, whereas the inside is still dry. It is quite difficult to disperse (and dissolve) such lumps. 

PHYSICAL PROPERTIES Glistening, colorless hexagonal crystals when pure, grayish black lumps of powder in commercial form insoluble in water MP (1300°C) BP (sublimes at 1500°C) SG (2.29). 

Carry out this preparation precisely as described for the a-compound, but instead of zinc chloride add 2 5 g. of anhydrous powdered sodium acetate (preparation, p. 116) to the acetic anhydride. When this mixture has been heated on the water-bath for 5 minutes, and the greater part of the acetate has dissolved, add the 5 g. of powdered glucose. After heating for I hour, pour into cold water as before. The viscous oil crystallises more readily than that obtained in the preparation of the a-compound. Filter the solid material at the pump, breaking up any lumps as before, wash thoroughly with water and drain. (Yield of crude product, io o-io 5 g.). Recrystallise from rectified spirit until the pure -pentacetylglucose is obtained as colourless crystals, m.p- 130-131° again two recrystallisations are usually sufficient for this purpose. 

CAUTION. The vapour of selenium dioxide is poisonous, and all operations involving the hot material, alone or in solution, should be performed in a fume-cupboard. If lumps of selenium dioxide have to be powdered in a mortar, the latter should also be in a fume-cupboard, with the window lowered as far as possible, to avoid inhaling the fine dust. (cf. p. 191)... 

Place 50 g. of o-chloronitrobenzene and 75 g. of clean dry sand in a 250 ml. flask equipped with a mechanical stirrer. Heat the mixture in an oil or fusible metal bath to 215-225° and add, during 40 minutes, 50 g. of copper bronze or, better, of activated copper bronze (Section 11,50, 4) (1), Maintain the temperature at 215-225° for a further 90 minutes and stir continuously. Pour the hot mixture into a Pyrex beaker containing 125 g. of sand and stir until small lumps are formed if the reaction mixture is allowed to cool in the flask, it will set to a hard mass, which can only be removed by breaking the flask. Break up the small lumps by powdering in a mortar, and boil them for 10 minutes with two 400 ml. 

Beckmann rearrangement of benzophenone oxime to benz-anilide. Dissolve 2 g. of benzophenone oxime in 20 ml. of anhydrous ether in a small conical flask and add 3 g. of powdered phosphorus pentachloride (or 3 ml. of pure tbionyl chloride). Distil off the solvent and other volatile products on a water bath CAUTION ether), add 25 ml. of water, boil for several minutes and break up any lumps which may be formed. Decant the supernatant liquid, and recrystallise, in the same vessel, from boiling alcohol. The product is benzanilide, m.p. 163° confirm this by a mixed m.p. determination with an authentic specimen. 

If either dry powders or inverse emulsions are not properly mixed with water, large lumps of polymer form that do not dissolve. This not only wastes material, but can also cause downstream problems. This is especially tme for paper where visible defects may be formed. Specialized equipment for dissolving both dry polymers and inverse emulsions on a continuous basis is available (22,23). Some care must be taken with regard to water quaUty when dissolving polyacrylamides. Anionic polymers can degrade rapidly in the presence of ferrous ion sometimes present in well water (24). Some cationic polymers can lose charge by hydrolysis at high pH (25). 

Stir or shake in a closed container until the powders are thoroughly mixed and no lumps of sulfur remain. 

Introduction of alkali metal into the flask containing liquid ammonia is most easily done with a powder funnel, which temporarily replaces a part of the equipment The cleaned lumps of metal are held above the funnel and cut into pieces (for handling alkali metals see our previous book "Preparative Polar Organometallic Chemistry , Springer-Verlag, 1987.)... 

To 1035 g. of syrupy arsenic acid (80-85 Per cent, sp. gr. 2.00/200 Note 1) in a 12-inch evaporating dish, is added 828 g. (800 cc.) of aniline (Note 2) in 100-cc. portions meanwhile, the lumps of aniline arsenate which are formed are broken up by rapid stirring with a porcelain spatula. When all the aniline has been added, the powdered solid is transferred to a 3-I. round-bottom flask equipped with a mechanical stirrer, a thermometer reaching to the lower part of the vessel, and a condenser arranged for downward distillation (Note 3) an additional 800 cc. of aniline is added and the flask slowly heated in an oil bath. The bath may be kept at a temperature not exceeding 170-175° as long as there is any considerable amount of unmelted material in the flask. When the contents of the flask have become liquid the temperature of the bath is dropped and the mixture held at 155-160° (inside temperature), with continual stirring, for at least four and a half hours. The mass will have assumed an intense violet color. 

Mix 100 g. of granulated aluminum with 90 g. of clean line sand and 90 g. of sulfur. Place the mixture in a fire-clay crucible embedded in sand in a safe place and ignite with fuse powder and a magnesium ribbon, as described in Exercise 85. After the reaction is completed, allow the crucible to cool. Break the crucible, put the contents in an evaporating dish, and treat with water to decompose the aluminum sulfide. This should be done under the hood so that the copious fumes of poisonous H2S will be carried off. Wash away the slimy lumps of melted aluminum from such foreign matter as pieces of crucible. Place these pieces of metal in a beaker, gradually treat with commercial hydrochloric acid until the action has quieted down, then cover with the acid and let stand on the hot plate for several days,... 

PLACE A LUMP OF LIME (QUICKLIME, CALCIUM OXIDE) IN A CUSTARD CUP. ADD AS MUCH LUKEWARM WATER AS IT WILL ABSORB. LIME HEATS UP, GIVES OFF STEAM, CRUMBLES INTO POWDER OF SLAKED LIME (CALCIUM HYDROXIDE). 

G) DROP INTO A DRY TEST TUBE /4 TEASPOON POWDERED SULFUR AND A LUMP OF CANDLE WAX AS LARGE AS A PEA. SET UP APPARATUS AS SHOWN. 

WHEN WATER IS ADDED TO LUMPS OF QUICKLIME (CoO), THEY CRUMBLE INTO A WHITISH POWDER OF SLAKED OK HYDRATED LIME (Co(OH)a). (SEE ALSO PAGE 45.)... 

HAMMER LUMPS OF BITUMINOUS COAL INTO A COARSE POWDER. FILL FUNNEL WITH IT. BRING FUNNEL INTO LARGE JAR. 

DISSOLVE 1h TEASPOON SOAP POWDER OR FLAKES IN 50 ml WARM WATER. ADD 10 ml HYDROCHLORIC ACID. YOU WILL GET LUMPS OF THE FATTY ACIDS OF WHICH SOAP IS THE SODIUM SALT—MOSTLY STEARIC AND PALMITIC ACIDS. STEARIC ACID IS ADDED TO PARAFFIN IN THE MAKING OF CANDLES. 

The apparatus for method (I) under SnCU (No. 84) is used with an ice-cooled receiver. Ten grams of commercial silicon (No. 2) in the form of powder or small lumps are employed the element is heated to about 400°C after the air in the reaction flask has been displaced by dry chlorine. A steady flow of gas is maintained the heat under the... 

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