Where Does Salt Come From?
Salt comes from salt lakes, salt wells, underground salt mines, and from the sea. Most of the salt that we sprinkle on our food is mined from thick salt beds, or large layers, deep in the ground. A very long time ago, salty ocean water lay where the salt beds are now. But the water dried up and large deposits of salt were left behind. This salt is called rock salt.
Later on, the salt was covered with other rocks. Miners, using compressed air drills, cut the solid salt away in great blocks. The salt is then crushed and sent to refining plants. Salt is one of the most common minerals on earth. The vast oceans of our planet hold four million cubic miles of salt and in the bedrock is a further one million tons. Depending on how we extract the salt it is called sea salt, rock salt or vacuum salt.
Sea salt: Most of the salt is in the oceans. Man has since ancient times obtained salt from there. A method for the production of sea salt, used for many centuries, is to allow seawater to evaporate into a kind of shallow pond, called a saline. The salines are placed in rows after another, leading the water from saline to saline. For each saline the salinity of the water is higher than in previous one. As the water evaporates faster, the process like this is faster than if we would let the water evaporate away in just a saline.
Salt is harvested around once a year. After harvesting, the salt is washed, dried and strained in order to obtain different grain sizes. In places where the climate is sufficiently warm and dry for the evaporation of this kind, sometimes sea salt is produced by taking the sea salt in large pans and gently warming it them from below so that the water evaporates.
Rock salt: Rock salt is mined in salt mines. Salt deposits underground, the remnants of the lost sea. Sea water has evaporated and the salt has wedged into the bedrock when the earth’s crust has moved. In some places where salt is sold the stocks are very deep.
In Germany, for example, there are layers 1000 meters deep, and there are also large salt deposits in Poland and Denmark. Before rock salt is mined, when it still remains below ground, it is customary to call it rock salt. Rock salt is used for roads with salts for de-icing.
Vacuum Salt: Vacuum salt is underground Sea Salt that has been refined. It is pumped into clean water in the large salt deposits and dissolves the salt to a salt solution. This brine is purified from contaminants with special chemicals and the water is then allowed to boil away, either under pressure or under vacuum (negative pressure).
The salt that remains should then be > 99.9% pure sodium chloride. Boiling can also be used to control the size of salt grains, so as to obtain rough-grained or fine-grained salt, depending on what you want. The product you are then left with is just the vacuum salt.