The natural bonding of sodium and chloride forms salt. Its chemical symbol is NaCl. Salt is as essential to life as food and water. It is indispensable in the chemical industry where it is a raw material starting point for a vast range of chemical products. Salt is critical to life, is consumed by humans and is present in literally millions of food products.
The fascinating history of 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 located throughout the world. All the centres of civilisation in antiquity sprang up in valleys where the three essentials of life - food, water and salt - were readily available. When the population grew beyond local salt resources people engaged in trade or war to get this essential commodity.
Salt's political and economic importance can be traced back to as early as 2000 BC when the Shantung province of China supplied the court of Emperor Yu with salt. Possibly the earliest traders in salt were the Phoenicians during the period 1200 BC to 300 BC.
So critical was the need for salt in the Roman Empire that, when ocean levels rose in the 1st century BC and wiped out the ancient coastal salt works, the Romans conquered Palestine for the salt located in the Dead Sea. Throughout Roman history the army received salt as part of their pay and from this "salarium argentum" the future English word "salary" was derived. Later, during the Dark Ages, the key cities of Northern Europe became production centres of salted fish using salt from salt marshes and brine springs. Vast forests were cut and burned to extract salt from brine by evaporation.
- It takes about 60 million tonnes of sea water to produce one million tonne of salt.
- It takes about 18 months to move the sea water through the series of ponds and to grow the salt ready for harvesting.
- Salt is harvested - similar to wheat - where a harvester scrapes the salt up and puts it into a truck.
- The most abundant source of salt is the ocean (comprising about 2.5 per cent NaCl) which is estimated to contain 44 x 1015 million tonnes of salt. This amount of salt would cover the world's continents to a depth of 35 metres.
- The total area under evaporation at Dampier Salts three sites is 19,500 hectares. This is the equivalent of around 27,900 soccer fields.
- At its three sites Dampier Salt evaporates on average 1,100,000,000 litres of water a day. This quantity of water would fill over 18,000 household swimming pools.
- The solar energy used in evaporation is equivalent to consuming about 27 million tonnes of coal per annum. If this water was evaporated using electricity, this would require a 29,000 megawatt power station
- Typical ships loaded by Dampier Salt are'Handymax' ships of around 45,000 tonnes each and 'Panamax' ships of around 70,000 tonnes. The largest ship ever loaded was a 'Mini Cape' of 93,450 tonnes.
- The marine ecosystem is managed in the ponds to control nutrients and marine growth that would otherwise become unbalanced and affect salt quality. This is managed by maintaining different varieties of sea life, particularly milkfish and brine shrimp which eat the nutrients coming in with the seawater and help keep the brine clear.
- Dampier salt is the world's largest exporter of solar salt.