At our Dampier and Port Hedland operations the salt is produced from seawater. The seawater is pumped into the operation and 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 pure Sodium Chloride (NaCl) 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.
Approximately once a year, each crystalliser is harvested by a mechanical harvester after 20 to 40 centimetres of salt has been deposited. The salt is then washed to remove impurities and stockpiled for shipment. Dedicated stockpile and ship-loading facilities are located at Mistaken Island (Dampier) and the port of Port Hedland.
At Lake MacLeod, the brine comes from a natural salt-rich aquifer which lies below the surface of the lake. The same processes for crystallisation, harvesting, washing, stockpiling and ship loading used at Dampier and Port Hedland are used at Lake MacLeod. The Lake MacLeod salt is shipped from dedicated facilities at the port of Cape Cuvier.