Chlorine metallurgy

V.A. Bessonova, V.I. Konstantinov, L.A. Stalyarova, E.G. Polyakov, Abstracts of reports on confer. Preparation of pure powders of refractive metals by method of chlorine metallurgy. IMet AN SSSR, Moscow, (1974) 22. 

This invention created a new technique, chlorine metallurgy, and the whole industrial world showed a keen interest in it (Figure 18.4), for the production of not only titanium but also other expensive metals and alloys of great technical importance. 

Sihcon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between sihcon carbide and a variety of compounds at relatively high temperatures. Sodium sihcate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal sihcide. Sihcon carbide decomposes in fused alkahes such as potassium chromate or sodium chromate and in fused borax or cryohte, and reacts with carbon dioxide, hydrogen, ak, and steam. Sihcon carbide, resistant to chlorine below 700°C, reacts to form carbon and sihcon tetrachloride at high temperature. SiC dissociates in molten kon and the sihcon reacts with oxides present in the melt, a reaction of use in the metallurgy of kon and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new sihcon nitride-bonded type exhibits improved resistance to cryohte. 

The most chemical-resistant plastic commercially available today is tetrafluoroethylene or TFE (Teflon). This thermoplastic is practically unaffected by all alkahes and acids except fluorine and chlorine gas at elevated temperatures and molten metals. It retains its properties up to 260°C (500°F). Chlorotrifluoroethylene or CTFE (Kel-F, Plaskon) also possesses excellent corrosion resistance to almost all acids and alkalies up to 180°C (350°F). A Teflon derivative has been developed from the copolymerization of tetrafluoroethylene and hexafluoropropylene. This resin, FEP, has similar properties to TFE except that it is not recommended for continuous exposures at temperatures above 200°C (400°F). Also, FEP can be extruded on conventional extrusion equipment, while TFE parts must be made by comphcated powder-metallurgy techniques. Another version is poly-vinylidene fluoride, or PVF2 (Kynar), which has excellent resistance to alkahes and acids to 150°C (300°F). It can be extruded. A more recent development is a copolymer of CTFE and ethylene (Halar). This material has excellent resistance to strong inorganic acids, bases, and salts up to 150°C. It also can be extruded. 

E.A. Brocchi, P.K. Jena, F.J. Moura, O. Barbosa-Filho, R.J. de Carvalho, Chloride metallurgy 2002 Practice and theory of chlorine/metal interaction, Annual Hydrometallurgy Meeting, Oct. 19-23,2002,1 (2002) 229. 

In addition to making organic chlorine compounds, a significant fraction of CI2 production is used to make inorganic halides. One important use, described in Chapter 20, is in the metallurgy of titanium, in which molecular chlorine is used to convert Ti02 into TiCl4, which is easy to purify by distillation. 

Used industrially as a chlorinating agent, dehydrating agent, catalyst, in the manufacture of pharmaceuticals, and in aluminum metallurgy. 

This book examines comprehensively the chlorine industry and its effects on the environment. It covers not only the history of chlorine production, but also looks at its products, their effects on the global environment and the international legislation which controls their use, release and disposal. Individual chapters are dedicated to subjects such as end use processes, water disinfection and metallurgy, environmental release of organic chlorine compounds, polychlorinated biphenyls, legal instruments and the future of the chlorine industry. 

The early sources of phenol were the destructive distillation of coal and the manufacture of methyl alcohol from wood. In both cases, phenol was a by-product. Recovered volumes were limited by whatever was made accidentally in the process. Initial commercial routes to on-purpose phenol involved the reaction of benzene with sulfuric acid (1920), chlorine (1928), or hydrochloric acid (1939) all these were followed by a subsequent hydrolysis step (reaction with water to get the -OH group) to get phenol. These processes required high temperatures and pressures to make the reactions go. They re multistep processes requiring special metallurgy to handle the corrosive mixtures involved. None of these processes is in commercial use today. 

Uses/Sources. Intermediate in organic synthesis, especially production of toluene diisocyanate and polymethylene poly-phenylisocyanate in metallurgy to separate ores by chlorination of the oxides and volatilization occurs as a product of combustion whenever a volatile chlorine compound comes in contact with a flame or very hot metal originally manufactured as an agent for chemical warfare during World War I... 

K2TiF6, in addition to applications in metallurgy, is used in the preparation of dental fillings.3 [Ti(H20)6]Cl3 is used as a bleaching agent in cases where chlorine is inapplicable.4... 

Phosgene is widely used as a chemical intermediate. It is used in metallurgy and in the production of pesticides, herbicides, and many other compounds. It is a by-product of chloroform biotransformation and can be generated from some chlorinated hydrocarbon solvents under intense heats. Phosgene has been used as a chemical warfare agent. 

Use Amalgams, catalyst, electrical apparatus, cathodes for production of chlorine and caustic soda, instruments (thermometers, barometers, etc.), mercury vapor lamps, extractive metallurgy, mirror coating, arc lamps, boilers, coolant and neutron absorber in nuclear power plants. 

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