Chemical conversion process

Chemical conversion processes can also be used for moisture and oxygen removal. These tend to be the same ones developed for the smaller point-of-use purifiers. Consequently there is Httle economy of scale and they are seldom able to be regenerated. 

High density tungsten alloy machine chips are recovered by oxidation at about 850°C, foUowed by reduction in hydrogen at 700—900°C. Typically, the resultant powders are about 3-p.m grain size and resinter readily. There can be some pickup of refractory materials used in furnace constmction, which must be controUed. This process is important commercially. Eor materials that may be contaminated with other metals or impurities, the preferred recovery process is the wet chemical conversion process used for recovery of tungsten from ores and process wastes. Materials can always be considered for use as additions in alloy steel melting. 

Pyrolysis Of the many alternative chemical conversion processes that have been investigated, pyrolysis has received the most attention. Pyrolysis has been tested in countless pilot plants, and many full-scale demonstration systems have been operated. Few attained any longterm commercial use. Major issues were lack of market for the unstable and acidic pyrolytic oils and the char. 

Chemical conversion. See also Chemical conversion processes of argon, 13 460 of nitrogen, 13 458—459 of oxygen, 13 459 460 of specialty gases, 13 462 Chemical conversion coatings, 15 251 Chemical conversion purifiers, 13 458,... 

Chemical conversion processes, for high purity gases, 13 457 Chemical corrosion, of magnesium... 

Knowledge about chemical conversion processes which take place in aquatic and terrestic systems. Also the knowledge and experience of the chemical industry may be of interest in the development of new chemical treatment processes. 

Straight-run gasoline gasoline produced from petroleum by distillation, without use of cracking or other chemical conversion processes. Its octane number is low. 

The major source of hazardous metals from chromating and other chemical conversion processes, as well as from electro- and electroless plating, is generally the process baths themselves. Spent cleaners and etchants also can contain large quantities of metal removed from workpieces. 

Through modeling of global experiments it is possible to elucidate the mechanism and identify a number of rate coefficients that must be determined accurately. In this procedure sensitivity and reaction path analyses are essential tools. The sensitivity analysis identifies the bottlenecks in the chemical conversion process, that is the rate-controlling elementary reactions. Reaction path analysis provides information about the major reaction pathways responsible for the production and consumption of each species. 

However, the concentration of elemental phosphorus in effluents from industries that produce phosphorus compounds is much lower, compared to industries that do not use chemical conversion processes for producing final products (e.g., WP/F production). White phosphorus also enters water when treated or untreated effluents are released from munitions production facilities that use white phosphorus. Before water recycling measures were implemented at the Pine Bluff Arsenal in Arkansas, the effluent water (phossy water) from the facility contained <53.4 mg/L of white phosphorus (Pearson et al. 1976). 

Hydrolysis usually refers to the replacement of a sulfonic group (-S03H) or a chloro group (-C1) with an hydroxyl group (-OH) and is usually accomplished by fusion with alkali. Hydrolysis uses a far wider range of reagents and operating conditions than most chemical conversion processes. 

Table 3 Chemical conversion processes for hazardous waste...

Oil refineries are complex plants. Besides physical processes such as distillation and extraction, a large number of different chemical conversion processes are applied. Catalysis plays a crucial role in these processes. The most important ones are ... 

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