Caustic soda (sodium hydroxide) 

Caustic soda (sodium hydroxide) is an important inorganic chemical produced by the electrolysis of salt (or less commonly from natural deposits of soda ash on reacting with lime). World production of caustic soda is about 45 million tonnes used to produce a broad range of inorganic chemicals and used in general manufacturing, mineral processing and water treatment.

Typical production profile

In other words it require around 30 gigajoules of gas to produce 1 tonne of caustic and 1 tonne of chlorine (concurrently).

Use
Australia imports about 1.2 million tonnes of caustic soda per year for the production of alumina. The caustic soda is imported as 50 per cent liquid.

Other applications of caustic including for the chlorination (sterilisation) of domestic water and waste, and other domestic market products (including for manufacture of as hypochlorite) at 145 00 tonnes and the manufacture of sodium cyanide at 90 000 tonnes.

Trade
Australia uses around 1.2 million tonnes of caustic soda to produce 13 million tonnes of alumina and a further 0.25 million tonnes for other domestic applications.

Caustic production is less than 0.25 million tonnes.

Prices
International caustic soda prices have been very volatile ranging from about US$30 per tonne (FOB) to ten-times higher at US$300 per tonne as during the late 1980s. Freight costs to Australia are typically US$40 per tonne resulting in a landed price as low as A$100 per tonne. Prices are countercyclical to that of its co-product chlorine and chlorine derivatives. 

Manufacture in Australia
Manufacture in Australia is in chloralkali production centres primarily dedicated for the required chlorine which is hazardous and hence expensive to transport so that the caustic soda is a by-product.

Description of manufacture in Australia see caustic and chlorine.

Outlook
A chloralkali plant integrated into a petrochemical complex in Western Australia is being promoted for the Pilbara region given the proximity of gas and salt inputs. A smaller chloralkali plant may also become viable in the Goldfields region of Western Australia with the availability of pipeline gas as discussed in relation to sodium cyanide and ammonium nitrate.