Salt

The most abundant source of salt is from the ocean. The other major sources of salt are inland waters, salt domes and sedimentary deposits of salt located throughout the world.

Salt production
At Dampier and Port Hedland, salt is produced from seawater. The seawater flows through a series of ponds. Evaporation, due to the energy of the sun and assisted by the wind, results in the water becoming progressively more concentrated.  When this brine is saturated with salt (sodium chloride), it is pumped into crystallising ponds (crystallisers) where further evaporation causes salt to crystallise as a solid deposit. The brine which remains after most of the salt has crystallised is called bitterns, and this is returned to the ocean.

About once a year, each crystalliser is harvested by a mechanical harvester after 20 to 40 centimetres of salt has been deposited. The salt is washed to remove impurities and stockpiled for shipment. There are dedicated stockpile and ship-loading facilities at Mistaken Island in Dampier and the port of Port Hedland in Western Australia.

At Lake MacLeod, brine comes from a natural salt-rich aquifer lying below the surface of the lake. The same processes used at Dampier and Port Hedland are used here for crystallising, harvesting, washing, stockpiling and ship-loading salt. Salt produced at Lake MacLeod is shipped from dedicated stockpiling and shipping facilities located at Cape Cuvier. Lake MacLeod is also a site for gypsum mining.

In 2006, Dampier Salt produced about 8.3 million tonnes of salt.

Uses of salt
Salt is mainly used in the chemical industry in the production of plastics, glass, detergents and a variety of chemicals. It is also used in food processing, food products and road de-icing. The major markets are in Asia, but markets in the Middle East, Africa and USA are also very important.

For more information on how Rio Tinto produces salt, please visit the Rio Tinto Minerals website.

For more information on our other products, see our corporate fact sheets.