Pulverising

If a sample of the anhydrous salt is taken from stock, it should preferably be melted, allowed to cool, and then pulverised. 

Lithium aluminium hydride if carelessly manipulated may be dangerous for two distinct reasons. The material is caustic, and should not be allowed to touch the skin it is particularly important that the finely divided material should be kept away from the lips, nostrils and eyes, and consequently pulverisation in a mortar must be carried out with the mortar in a fume-cupboard, and with the window drawn down as far as possible in front of the operator. This danger from handling has however been greatly reduced, for the hydride is now sold in stated amounts as a coarse powder enclosed in a polythene bag in a metal container this powder dissolves readily in ether, and preliminary pulverisation is unnecessary. 

Grind 10 g. of malt thoroughly in a mortar so that the grains are completely pulverised, add 50 ml. of water and macerate well. Allow to stand for about one hour, grinding up the mixture thoroughly from time to time, and then Biter through a Buchner funnel. 

Sodamide may be readily pulverised by grinding in a glass mortar under an inert hydrocarbon solvent (benzene, toluene, xylene, etc.). 

Into a 1-litre three-necked flask, equipped with a reflux (double surface) condenser, a mechanical stirrer (preferably of the Hershberg type. Fig. II, 7, 8) and a gas lead-in tube extending to near the bottom of the flask, place 200 g. (227 ml.) of dry benzene, 20 g. of paraformaldehyde (1) and 20 g. of finely-pulverised, anhydrous zinc chloride. Support the flask on a water bath so arranged that the level of the water in it is about... 

Moisture content affects a number of appHcations. The grindabiUty index, ASTM D409, measures the relative ease of pulverising coals and theoretically helps determine the capacity of pulverizers. In practice, low values of grindabiUty occur at moisture extremes and maximal grindabiUty occurs at intermediate moisture content. A small pulverizer to test grinding conditions for design purposes has been developed (20). 

L. D. Smoot and D. T. Pratt, eds.. Pulverised Coal Combustion and Gassification, Plenum Press, New York, 1979. 

Lithium chloride [7447-41-8] M 42.4, m 600 , 723 . Crysld from water (ImL/g) or MeOH and dried for several hours at 130 . Other metal ions can be removed by preliminary crystallisation from hot aqueous 0.0 IM disodium EDTA. Has also been crystallised from cone HCl, fused in an atmosphere of dry HCl gas, cooled under dry N2 and pulverised in a dry-box. Kolthoff and Bruckenstein [J Am Chem Soc 74 2529 1952] ppted with ammonium carbonate, washed with Li2C03 five times by decantation and finally with suction, then dissolved in HCl. The LiCl solution was evaporated slowly with continuous stirring in a large evaporating dish, the dry powder being stored (while still hot) in a desiccator over CaCl2. 

Potassium bromide [7758-02-3] M 119.0, m 734°, d 2.75. Crystd from distilled water (ImL/g) between 100° and 0°. Washed with 95% EtOH, followed by Et20. Dried in air, then heated at 115° for Ih, pulverised and heated in a vacuum oven at 130° for 4h. Has also been crystd from aqueous 30% EtOH, or EtOH, and dried over P2O5 under vacuum before heating in an oven. 

Tin (powder) [7440-31-5] M 118.7. The powder was added to about twice its weight of 10% aqueous NaOH and shaken vigorously for lOmin. (This removed oxide film and stearic acid or similar material sometimes added for pulverisation.) It was then filtered, washed with water until the washings were no longer alkaline to litmus, rinsed with MeOH and air dried. [Sisido, Takeda and Kinugama J Am Chem Soc 83 538 1961.]... 

Combustion of coal may take place in conventional fixed beds using lump coal and in which temperatures up to 1 300°C may be reached by entrained flow in which pulverised coal is injected into the combustion zone with the air, reaching temperatures up to 1 500°C or in the more recently developed systems of fluidised-bed combustion, again using pulverised coal but with... 

Fluidised-bed systems produce higher combustion intensities at lower temperatures than combustion of pulverised fuel in conventional fossil-fuel-fired boilers. The mineral matter for corrosion does not form fused salts and is not expected to release corrosive species. Fluidised bed combustors can, therefore, burn lower grade, cheaper fuel in smaller plant with better pollution control than traditional boilers... 

Eberle, Ely and Dillon tested commercial tubes in a small superheater receiving plant steam at 14MN/m and superheating it from 538° to 677°C. Penetration was estimated from scale thickness measurements after 6 950 h and comparison was made between the attack by steam on the inside of the tubes and that by flue gas from pulverised coal firing on the outside (Table 7.11). 

PsychrorneLry sec humidity determination Pugh. F. J, 205,228 PumiM. 1. 209, 228 Pulverised fuel particles 47 ... 

Alternative proeesses for the reeyeling of fibre-reinforeed plastie (FRP), and their applieation in Japan, are briefly reviewed. Pulverised waste has been used in plastie mouldings for automotive applieations, and in eement roof tiles. FRP may be burned in ineinerators and used to heat water, or as an additive to eement kilns, where the resin aets as a fuel and the glass and filler beeome eement raw materials. Pyrolysis, in eonjunetion with metal eatalysts, has been used to reduee the waste to oils or gases, and treatment with steam or supereritieal water has also been sueeessfully applied. 26 refs. 

Confusion as to what constitutes municipal waste is presenting an obstacle to the use of packaging waste as a fuel in cement kilns. Whilst cement kilns can bum hazardous waste, they cannot bum a wide range of non-hazardous materials, it is reported. The case of Castle Cement is described which planned to bum a range of non-hazardous commercial and industrial wastes. Some waste-fired combustion processes, however, such as UK Waste s Fibre Fuel operation have been granted derogations where fuel is manufactured by advanced mechanical processes, which includes the production of fuel pellets. This latter process would be pointless for the cement industry since their fuels have to be pulverised. The problems are further discussed with reference to current European legislation. 

These issues are really major ones in research laboratories dealing with specialty chemicals and first level scale-up. Filterability can be a problem with M catalysts supported on classic materials such as carbon, owing to their tendency to pulverisation to give nanometer-sized catalyst particles that turn out to be very difficult to be recovered and successfully reused. 

Confinement volume plays a huge role but cannot be modelled. The solidity of the closure does not perform any role. So a sheet of paper placed on the test tube is enough to transform the deflagration decomposition process of benzoyl peroxide into a detonation, which pulverises the test tube (this accident happened to the author but proved to be unrepeatable during a later test). So it is not a transition -al effect of pressure increase that plays an aggravating roie. 

The metal proves to be dangerous in the pulverised state and with Raney nickel... 

All the dangerous reactions involve the metal in the pulverised state and are the result of its reducing property. 

The only dangerous reactions cited deal with metal palladium, especially when it is in the pulverised state. 

When this acid was prepared in an autociave at a temperature of 115°C, a violent detonation occurr, which pulverised the apparatus. This accident was... 

Nitromethane was treated with lithium aluminiumhydride in diethyl ether medium and at ambient temperature. This was followed by an explosion which pulverised the equipment. This accident can be explained by the fact that there was a redox reaction, but also by the formation of nitromethane lithium, unless... 

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