Salt is the feedstock of the chlor-alkali industry which produces chlorine, caustic soda and the myriad other products formed from these basic chemicals. The chemical industry well-describes the chemical genealogy of salt with its “Chlorine Tree.” Globally, chlorine chemistry is the single largest market for salt, although in the U.S., where there are numerous areas with exploitable salt deposits, the salt produced for chemical production is often extracted directly by chemical companies and not by salt producers. In Europe and Japan, the chlor-alkali industry is more likely to buy its salt from a salt company.
Chemical companies pass an electrical current through saturated salt brine in a salt bridge, producing a oxidation-reduction (redox) chemical reaction. This electrolysis separates the gaseous chlorine, (Cl2), from the sodium hydroxide (caustic soda). Chlorine is an effective disinfectant and bleach. We use it to keep drinking water safe. And swimming pools. Downstream, vinyl chloride and polyvinyl chloride (PVC) and their derivatives are produced from chlorine. Caustic soda is used in pulp processing, and to make cellulose chemicals and their derivatives. Sodium chlorite is used in the textile industry. Other chemicals manufactured from salt are metallic sodium and sodium chlorate. Until 1986, salt was used to produce synthetic soda ash (NaCO3) in the U.S. by the Solvay process. Soda ash is now obtained naturally from trona mines.
Salt-based chemicals are used:
Learn more about how other industries use these products of chlorine chemistry .
Due to security concerns with the transportation of chlorine in tanker trucks and rail cars, including chemical terrorism (aka "toxic trains"), some chlorine users are using on-site chlorinators for “saltwater” swimming pools, drinking water purification and wastewater disinfection.