Chlorination industry

The toxicological problems associated with asbestos have been widely pubHshed and asbestos has been banned from most uses by the EPA. However, modem diaphragm cell chlorine plants have not had difficulty meeting the required exposure limits for asbestos fibers, and, as of 1990, the chlorine industry had an exemption allowing the continued use of asbestos as a diaphragm material. 

D. L. Peet, Membrane Durability in Chlor—Alkali Plants, Electrochemical Society Meeting, Honolulu, Hawaii, Oct. 1987 Proceedings of the Symposium on Electrochemical Engineering in the Chlor—Alkali and Chlorine Industries, PV. 88-2, 1988, pp. 329—336. 

Commercial metal anodes for the chlorine industry came about after the late 1960s when a series of worldwide patents were awarded (6—8). These were based not on the use of the platinum-group metals (qv) themselves, but on coatings comprised of platinum-group metal oxides or a mixture of these oxides with valve metal oxides, such as titanium oxide (see Platinum-GROUP metals, compounds Titanium compounds). In the case of chlor-alkaH production, the platinum-group metal oxides that proved most appropriate for use as coatings on anodes were those of mthenium and iridium. 

Success in the chlorine industry led to the incorporation of DSA in sodium chlorate [7775-09-9] NaClO, manufacture. The unique stmctural characteristics of the anode allowed for innovative designs in ceU hardware, which in turn contributed to the extensive worldwide expansion of the sodium chlorate industry in the 1980s. 

World production of Bra in 1990 was about 438 000 tonnes pa, i.e. about one-hundredth of the scale of the chlorine industry. The main producing countries are (tonnes) USA 177000, Israel 135 000, Russia 60000, UK 28 000, France 18 000 and Japan 15 000. The production capacity of Israel has recently increased almost threefold because of expanded facilities on the Dead Sea. Historically, bromine was shipped in individual 3-kg (net) bottles to minimize damage due to breakage, but during the 1960s bulk transport in monel metal drums (100-kg capacity) or lead-lined tanks (24 or 48 tonnes) was developed and these are now used for transport by road, rail and ship. The price of Bra in tank-car lots was 975/kg in 1990. 

Plants producing and handling halogens and halogen compounds Tantalum finds extensive use in the production and handling of hydrochloric and hydrobromic acid, chlorine and bromine and many of their derivatives. Absorbers, coolers and heaters which show considerable advantages in terms of heat-flux capabilities and corrosion resistance have been used on hydrochloric acid duties for over 40 years and condensers have been used in bromine plants for at least the same period. Typical applications of tantalum in the bromine and chlorine industries are listed in Table 5.27 . 

Table S.27 Typical applications of tantalum equipment in bromine and chlorine industry...

The detection of a potent dioxin impurity in a major herbicide has focused attention on the nature of chlorinated impurities in pesticides, and in a larger sense, impurities in all chlorinated industrial compounds used extensively in man s environment. The present 2,4,5-T controversy is overshadowed by the dioxin problem. Major disagreement still exists on their relative contributions to the teratogenic effects observed in chicks and the validity of interpretation of high dosage rates used to achieve these effects. We have avoided any assessment of the health-related aspects of dioxins but have dealt almost exclusively with dioxins as an environmental entity. 

This structure looks nothing like the structures of chlorine-containing compounds used in industrial processes. In fact, no dioxin is deliberately manufactured anywhere in the diverse chlorine industry. Nevertheless, dioxins are of concern for two reasons First, dioxins appear to be inevitable trace by-products of some reactions involving chlorine, particularly combustion and second, dioxins accumulate in the biosphere, where they have highly deleterious effects. 

Appreciable interest was stirred by the sucessful use of nonmetallic catalysts such as oxides and organic metal complexes in electrochemical reactions. From 1968 on, work on the development of electrocatalysts on the basis of the mixed oxides of titanium and ruthenium led to the fabrication of active, low-wear electrodes for anodic chlorine evolution which under the designation dimensionally stable anodes (DSA) became a workhorse of the chlorine industry. 

Of considerable interest was the demonstration that metalloporphyrins and the like can be used as nonmetallic catalysts in electrochemical reactions, nourishing hopes that in the future, expensive platinum catalysts could be replaced. Starting in 1968, dimensionally stable electrodes with a catalyst prepared from the mixed oxides of titanium and ruthenium found widespread use in the chlorine industry. 

The invention of the ruthenium based DSA electrode by H.B. Beer has had a major impact on the chlorine industry and has stimulated a number of investigations aimed... 

Dordrecht, Kluwer Academic Publishers, 2001, pp.xii, 429, ISBN 0792367979, 25cm, 32C38 CHLORINE AND THE ENVIRONMENT AN OVERVIEW OF THE CHLORINE INDUSTRY... 

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 chlorine industry really took off at the end of the 1890s with the installation of the first mercury cell units. Since then the industry has coped with many problems, the main one being the fixed amount of caustic soda per ton of chlorine out of the cells. There have always been imbalances on the demand for chlorine and the demand for caustic soda. The two products quite often go their own way and no reason is seen to change this situation. 

The industry responsible for the largest amount of WMPCs produced in 2001 was the alkalies and chlorine industry (SIC code 2812). (The Standard Industrial Classification [SIC] code is a system for categorizing all types of industries that operate in the United States.) The next four industries, in terms of WMPCs produced in 2001, were blast furnaces and steel mills (SIC code 3312), primary nonferrous metals (SIC code 3339), industrial inorganic chemicals (SIC code 2819), and storage batteries (SIC code 3691). Lead is an important by-product in all of these operations, accounting for the very large... 

B. Hileman, Concerns broaden over chlorine and chlorinated hydrocarbons. Chem. Eng. News April 19, 11-20 (1993) B. Hileman, J. R. Long, and E. M. Kirschner, Chlorine industry running flat out despite persistent health fears. Chem. Eng. News November 21, 12-26 (1994) I. Amato, The crusade against chlorine. Science 261, 152-154... 

However several POPs, particularly the OCPs and dioxins, remain at low levels in the Australian environment and several remain persistent at low levels in body fats and fluids of Australians. The levels reflect the past use and persistence of OCPs in the Australian environment, contamination of the food chain and the capacity of the body to metabolise and store in body fats. The dioxins remain due to the ubiquitous nature of their sources with combustion as a major source and their persistence. Future trends are likely to mean very low-level residues in human fats of DDE, cyclodienes, HCB, HCHs and dioxins in the long term. Their rate of decline will probably depend on removing HCB from chlorinated industrial chemicals and OCPs from the environment (e.g. remediation of contaminated soils) by hazardous waste treatment methods (e.g. physical, chemical and biological degradation or fixation) or secure landfill. 

Production and Use of Contaminated Chemicals and Certain Herbicides. CDDs are known trace contaminants of certain chlorinated industrial chemicals like chlorophenols (Buser 1987). CDDs can inadvertently form as by-products during the manufacture of chlorophenols. Since the 1930s, PCP and the tri- and tetrachlorophenols have gained recognition as fungicides, herbicides, insecticides, and precursors in the synthesis of other pesticides. 

Eurochlor. 2004. Chlorine industry review 2004—2005. Brussels (Belgium) Eurochlor. 29 p. 

Refs. [i] Bommaraju TV, O Brien TF (2005) Handbook of chlor-alkali technology. Springer, Berlin [ii] Chlorine Industry Review 2004-2005, EuroChlor... 

Prior to the development of the liquid chlorine industry, the only means of transporting chlorine was as bleach. Common practice in the early years was to absorb the chlorine in hydrated lime, Ca(OH)2, to form chloride of lime, CaOCl2. Easily transported as a solid, this... 

Energy Requirements. An electrochemical unit (ECU) in the chlorine industry represents the stoichiometric yield of 1 mole of Cl2 and 2 of... 

To reduce production of chlorinated organics during bleaching, the pulp and paper industry has replaced chlorine with chlorine dioxide. Chlorine dioxide or its primary precursor, sodium chlorate, can be produced by the low-tonnage chlorine industry with the same hardware that is used for synthesis of chlorine and hypochlorite. This simple transition from chlorine to chlorine dioxide synthesis may be the reason for the less-than-anticipated usage of hydrogen peroxide in the pulp and paper industry. Increasing use of chlorine dioxide could also lead to its applications in other effluent treatment areas such as industrial wastewater remediation. 

This demonstration marked the beginnings of the CFC industry as we know it today. Continuous processes were developed wherein a chlorocar-bon and HF were fed to a reactor containing antimony pentahalide, usually dissolved in the fluorinated reaction intermediates. Under reaction conditions, pentavalent antimony is somewhat unstable, reverting back to the trivalent state and chlorine. Industry practice is to feed chlorine to oxidize trivalent antimony back to the pentavalent state. In its simplest form the exchange reaction with CCI4 can be written as shown in Eqs. (4) and (5). Over the years, several improvements to such processes have been made... 

B. S. Gilliatt, EuroChlor, Chlorine Industry Review, 2004-2005, 6 www.eurochlor.org/ reviews. 

Exposure Registries. New York State has instituted a Heavy Metals Registry that monitors occupational exposure to heavy metals, including mercury. Cases are reported when mercury exposure is equal to or exceeds 50 g/L (ppb) in blood or 20 g/L (ppb) in urine. Between 1982 and 1986, 1,000 cases of mercury exposure were reported and linked to 47 companies. Most exposures (494 cases) occurred in workers in the alkali and chlorine industry, where mercury is used as a cathode because exposure occurs when the cells are opened the median blood mercury concentration was 76 g/L (ppb) (maximum concentration 916 g/L [ppb]). The second most frequent exposure category (213 cases) was the manufacture of industrial instruments, such as the manual assembly and fabrication of thermometers median blood mercury concentration was 145 g/L (ppb) and the maximum concentration was 889 g/L (ppb) (Baser and Marion 1990). 

Shaw BP, Sahu A, Panigrahy AK. 1986. Mercury in plants, soil, and water from a caustic chlorine industry. Bull Environ Contam Toxicol 36 299-305. 

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