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United States to keep chlorine production high, which impacts both markets and production in this country (DOW 1999). Prices for both chlorine and caustic soda are impacted by changes in vinyl exports to Asia and weakness in the pulp and paper industry. Important Asian economies (e.g., Japan) will continue to drive demand for both these products and set the pace of new production facilities in the United States. The fact that the United States remains competitive in the chlorine- caustic-vinyl cycle can be attributed to three factors: our large supplies of energy and raw materials (salt and ethylene), and our large-scale economy. With the exception of Taiwan, world scale vinyl plants are not being built in Asia (DOW 1999). Other forces affecting the market for chlor- alkalis include environmental regulations aimed at curtailing chlorine use. For example, restrictions on the production or disposal of products that require large amounts of chlorine (e.g., PVC, chlorinated solvents) have had a negative impact on the chlorine market. Several environmental groups and initiatives (e.g., International Joint Commission of Great Lakes Water Quality) are calling for a gradual phaseout or immediate ban on chlorine and chlorinated compounds as industrial feedstocks, which is also impacting commercial use of chlorine (CCC 1995, EPA 1995a, CCC 1996, Ayres 1997). However, demand for PVC has been a significant driver in the growth of chlorine use both in the United States and globally. The industrialization of Asia is expected to drive PVC demand and chlorine growth well into the next century. Until a non-chlorine replacement for PVC is developed, demand will remain strong (DOW 1999). Demand for sodium hydroxide may also be impacted by users switching to soda ash to avoid shortages of sodium hydroxide (like the worldwide shortage that occurred in the late 1980s). Soda ash is very plentiful in the United States and is obtained almost entirely from natural sources of trona ore . However, it is more expensive to mine soda ash than to produce 50 percent caustic, so increased use of soda ash is not likely to occur unless the price of caustic is relatively high (Chenier 1992, DOW 1999). Demand for sodium hydroxide may also be impacted as pulp and paper mills increasingly look for cost-effective ways to recycle sodium hydroxide from spent pulping liquor. Currently, however, most of these alternatives cannot compete on a capital and cost basis with caustic soda production, and will only impact demand when they become economically viable (EPA 1995a, CHEMWK 1999). Chlorine is difficult to store and transport economically. As a result, chlorine and caustic soda are usually produced in close proximity to end-users (primarily chemical manufacturers and pulp and paper mills). Geographically, about 72 percent of chlorine production takes place in chlor-alkali facilities located along the Gulf Coast; other production occurs in the vicinity of pulp mills of the Southeast and Northwest. 6.1.1 Manufacture of Chlorine and Sodium Hydroxide Chlorine and Sodium Hydroxide Are Co- Products of Brine Electrolysis Chlorine was first discovered in 1774 by the German chemist Scheele, and was identified as an element in 1810 by an English scientist named Davy. Caustic soda, or sodium hydroxide, has been an important industrial chemical since1853. Until 1892 sodium hydroxide was produced by the reaction of slaked lime and soda ash. That year, the electrolysis of brine was discovered as a method of making both sodium hydroxide and chlorine. Since the 1960s electrolysis has been the predominant technique employed to manufacture these two important chemicals (Chenier 1992, Orica 1999). Although electrolysis of brine is the primary production method, technologies for converting aqueous hydrochloric acid to chlorine are also used in the United States and Europe. A process 177PDF Image | The Chlor-Alkali Industry
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