Salt mining extracts natural

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quanti ...

deposits from underground. The mined salt is usually in the form of

halite Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, ...

(commonly known as rock salt), and extracted from

evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...

formations.

History

Before the advent of the modern

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal co ...

and earth-moving equipment, mining salt was one of the most expensive and dangerous of operations because of rapid dehydration caused by constant contact with the salt (both in the mine passages and scattered in the air as salt dust) and of other problems caused by accidental excessive sodium intake. Salt is now plentiful, but until the

Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

, it was difficult to come by, and salt was often mined by slaves or prisoners. Life expectancy for the miners was low. Ancient China was among the earliest civilizations in the world with cultivation and trade in mined salt. They first discovered natural gas when they excavated rock salt. The Chinese writer, poet, and politician Zhang Hua of the Jin dynasty wrote in his book '' Bowuzhi'' how people in Zigong,

Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of th ...

, excavated natural gas and used it to boil a rock salt solution. The ancient Chinese gradually mastered and advanced the techniques of producing salt. Salt mining was an arduous task for them, as they faced geographical and technological constraints. Salt was extracted mainly from the sea, and salt works in the coastal areas in late imperial China equated to more than 80 percent of national production. The Chinese made use of natural crystallization of salt lakes and constructed some artificial evaporation basins close to shore. In 1041, during the

Song dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the res ...

, a well with a diameter about the size of a bowl and several dozen feet deep was drilled for salt production. In Southwestern China, natural salt deposits were mined with bores that could reach to a depth of more than , but the yields of salt were relatively low. As salt is a necessity of life, salt mining played a pivotal role as one of the most important sources of the Imperial Chinese government's revenue and state development. Most modern salt mines are privately operated or operated by large multinational companies such as K+S, AkzoNobel,

Cargill Cargill, Incorporated, is a Privately held company, privately held American global food corporation based in Minnetonka, Minnesota, Minnetonka, Minnesota, and incorporated in Wilmington, Delaware. Founded in 1865, it is the largest privatel ...

, and Compass Minerals.

Mining regions around the world

Some notable salt mines include:

Idiomatic use

In slang, the term , and especially the phrase , refers ironically to one's workplace, or a dull or tedious task. This phrase originates from in reference to the Russian practice of sending prisoners to

forced labor Forced labour, or unfree labour, is any work relation, especially in modern or early modern history, in which people are employed against their will with the threat of destitution, detention, violence including death, or other forms of e ...

in Siberian salt mines.

References

External links

Mohammedia Rock Salt Company
{{Portal bar, Food Ancient Roman technology Chinese inventions Mining

History

Mining regions around the world

Idiomatic use

See also

References

External links