The element
chlorine (Cl) is one of the 92 natural elements found on our planet. You'll find it in the 17th column of the famous Periodic Table of the Elements. Only 16 elements constitute 99,5% of the earth crust. In this group of elements, chlorine ranks 11th.
At room temperature, the molecule chlorine (Cl2) is a greenish gas (see picture left).
Chlorine gas (Cl2) is made from common kitchen salt (sodium chloride) and water.
About 50 quadrillion tonnes of dissolved sodium chloride (common salt) are found in the world’s oceans and seas. However, less than a third of salt production stems from seawater. The majority comes from rock salt mines hundreds of meters below the surface of the Earth.
Huge machines with sharp rotors tunnel their way through the rock salt. An automatic electrohydraulic drilling machine bores rows of holes about 14 meters deep into the ceiling. They are then filled with explosives which are detonated once all the workers leave the mine. The crushed rock salt is then transported by conveyor belt to the shaft where it is sent to the surface.
Germany is one of the world’s main sources of salt. The country boasts one of the largest salt mines in Europe which is located in Borth. Subterranean deposits are estimated at more than 200,000 million tonnes.
Another method of extracting salt is to pour hot water into underground salt plugs. The salt dissolves and the brine is pumped to the surface. The advantage of this method is that the extraction process can be regulated so that many of the impurities in the salt remain underground. The brine is concentrated by evaporation in large vacuum plants, yielding 99.9% pure salt.
Chlorine and its co-product, caustic soda, are two basic chemical industry building blocks for vast numbers of everyday products that we take for granted today. Examples include pharmaceuticals, medical devices, windows, flooring and pipes.
What is chlorine?
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