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Open-pan salt making is a method of salt production wherein salt is extracted from
brine
Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for br ...
using open pans.
Virtually all European domestic salt is obtained by solution-mining of underground salt formations, although some is still obtained by the solar evaporation of sea water.
Types of Open-Pan Salt Production
Salt is made in two ways traditionally. Rock salt is mined from the ground. The other type known as white salt is made by the evaporation of brine. Brine is obtained in several ways. Wild brine streams, occurring from the natural solution of rock salt by ground water, can come to the surface as natural brine springs or can be pumped up to the surface at well, shafts or boreholes. Artificial brine is obtained through solution mining of rock salt with fresh water and is known as ‘controlled brine pumping’. A Bastard Brine used to be made by allowing fresh water to run through abandoned rock salt mines. A Salt-on-Salt process strengthens brine by dissolving rock salt, and/ or, crystal salt in weak brine or sea water prior to evaporation. Solar Evaporation uses the sun to strengthen and evaporate sea water trapped on the sea-shore to make sea salt crystals, or to strengthen and evaporate brine sourced from natural springs where it is made into white salt crystals.
This led to three types of salt production all of which used a variation of the open-pan salt method:
Coastal salt production: The process involved solar evaporation of seawater, followed by artificial evaporation of salt using the open-pan technique in structures known as ‘
saltern
A saltern is an area or installation for making salt. Salterns include modern salt-making works (saltworks), as well as hypersaline waters that usually contain high concentrations of halophilic microorganisms, primarily haloarchaea but also oth ...
s’.
Inland salt production: The process used brine from natural brine streams flowing over buried salt deposits that were pumped up from the ground and evaporated using the open-pan technique.
Salt Refining.: This was a large-scale salt industry developed in coastal locations and based on a combination of inland salt mining and coastal salt production. Referred to as salt refining or salt-on-salt, the process combined weak brine from seawater with mined rock salt, and evaporated the brine into a white salt.
Inland Open-Pan Salt Production
Open-pan salt production was confined to a few locations where geological conditions preserved layers of salt beneath the ground. Only five complexes of inland open-pan salt works now survive in the world:
Lion Salt Works
The Lion Salt Works is the last remaining open pan salt works in Marston, near Northwich, Cheshire, England. It closed as a work in 1986 and is now preserved as a museum.
History
John Thompson Junior and his son Henry Ingram Thompson, a membe ...
, Cheshire, United Kingdom;
Royal Saltworks at Arc-et-Senans
The Saline Royale (Royal Saltworks) is a historical building at Arc-et-Senans in the department of Doubs, Eastern France. It is next to the Forest of Chaux and 29.2 kilometres (18.1 miles) to the southwest of Besançon. The architect was Claude- ...
, Salins-les-Bains, France; Saline Luisenhall, Göttingen, Germany;, the Salinas da Fonte da Bica,
Rio Maior
Rio Maior () is a municipality in the Santarém District in Portugal. The population in 2011 was 21,192, in an area of 272.76 km².
The present mayor is Isaura Morais of the Social Democratic Party (PSD), the first woman to be elected mayor ...
, Portugal; and the Colorado Salt Works, USA. The two French saltworks at Salins-les-Bains and Arc-et-Senans became a
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It ...
World Heritage Site
A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...
in 1982.
The earliest examples of pans used in the solution mining of salt date back to ancient times when the pans were made of ceramics known as
briquetage
Briquetage or very coarse pottery (VCP) is a coarse ceramic material used to make evaporation vessels and supporting pillars used in extracting salt from brine or seawater. Thick-walled saltpans were filled with saltwater and heated from below ...
and Cheshire VCP (Very Coarse Pottery), a coarse low-fired pottery. In Britain, these materials began to be identified from the early 1980s in the Marches (Herefordshire, Worcestershire, Shropshire and Wales) and later in Northern England
The Romans introduced small (3 ft square) pans made from
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
using wood as a fuel. In Britain they established towns for salt production at Droitwich in Worcestershire, and Nantwich,
Middlewich
Middlewich is a town in the unitary authority of Cheshire East and the ceremonial county of Cheshire, England, east of Chester, east of Winsford, southeast of Northwich and northwest of Sandbach. The population at the 2011 Census was 13,595. ...
and Northwich in Cheshire. In the early Middle Ages these developed into the 'wich' towns of Cheshire. Small 'wich' houses containing several lead pans to evapourate the brine into salt, clustered around brine springs within each of the towns. The open-pan process continued largely unchanged throughout the medieval period. A 17th-century German wood-cut by Georgius Agricola shows the process in detail. Excavated evidence has uncovered wooden rakes to draw salt crystals to the side of the pan, and conical wicker baskets (barrows) in which the wet salt was drained and dried.
By the 17th century, the pans started to be made from
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
, firstly in pans by . William Brownrigg writing in 1748, in his ‘Book of Common Salt’, shows a wood-cut of one of these salt-making pans. The change to iron (from lead) coincided with a change from wood to coal for the purpose of heating the brine. Gradually, the pans increased in size. For example, Christoph Chrysel writing in 1773, in his ‘Remarkable and very useful Information about the present Salt Works and Salt pans in England’, noted that salt pans were wide and long and deep. Brine would be pumped into the pans, and concentrated by the heat of the fire burning underneath. As crystals of salt formed these would be raked out and more brine added.
By the 19th century, the open-pan salt process had reached its zenith in Britain. Two principal regions of production existed, Worcestershire and Cheshire. Brine shafts were sunk to the level of the brine stream that flowed over the natural rock salt or halite. Brine was pumped from the ground using wind and later, steam-driven beam engines, and redistributed to large iron pans.
These fell into two categories: Smaller fine pans were and about wide and about deep. They were housed in pan houses and had associated stove houses. The salt was evaporated in the pan at a high temperature of around . This produced higher quality grades of salt including 'Butter Salt', 'Dairy Salt', 'Calcutta Salt' and Lagos Salt'. After about six hours the salt would crystallise out of the brine solution and fall to the base of the pan. It was then the job of the lumpman to rake-up the salt and skim it into wooden tubs to create lumps, hence the name. The lumps would then be sent to the stove house or 'hothouse' to dry. Here the lumps would be piled up and the recycled heat from the fires beneath the pans used to heat the room before exhausting through a chimney. The salt lumps would be 'lofted' or passed up to a warehouse above by a man called the lofter. The lumps would be sold known as 'hand-it' lumps or processed in a crushing mill and then bagged.
The second larger common or fishery pans were long x wide x deep and were built outside. The pans were usually heated by coal and were controlled by a fireman. The larger pans would be heated at a much lower temperature between for several days or even weeks. This would produce a much denser crystal with a variety of sizes known as common or fishery salt. Common salt was used for a variety of reasons but included the chemical industry. Fishery salt was used in the packing and processing of fish. The salt would not be made into lumps but instead was skimmed and turned out onto the wooden platforms around the pans. It was then barrowed in large wooden store houses.
Occupations in an Open-Pan Salt Works
The following are historical names given to occupations in open pan salt works, primarily in
Cheshire
Cheshire ( ) is a ceremonial and historic county in North West England, bordered by Wales to the west, Merseyside and Greater Manchester to the north, Derbyshire to the east, and Staffordshire and Shropshire to the south. Cheshire's county t ...
, England.
*Lumpman: A lumpman would work on pans that made fine salt crystals, which were known as 'fine pans' or 'lump pans'. The quality of the salt generally depended on the state of the fires which crystallized the salt by forcing off the water. Therefore, each pan had its own individual furnace and chimney, which the lumpman was responsible for controlling. Wooden moulds were filled with salt crystals from the pans to produce a hard block (lump) of fine salt. Lumpmen were paid piecework, and would start at 3 or 4 in the morning, and could expect to work 12- to 16-hour days.
*Waller: A waller would be under the charge of the lumpman, and was responsible for the initial draining of the salt. Salt was drained by being raked to the side of the pans, and then transferred using skimmers onto the hurdle boards (walkways) around the pans. A waller is an ancient name for a saltmaker. He would have been hired on a daily basis.
*Fireman: In addition to the fine pans there were other 'common pans', used to make coarser salt. Because the production of common salt required slower burning fires, it was possible for a single fireman to have charge of several common pans, which could be up to long.
*Pan-smith: This was originally the name given to the man who made the salt-making pans.
See also
*
Alberger process
The Alberger process is an industrial method of producing salt from rock salt.
Method
The Alberger process begins by heating brine under high pressure with a series of heaters. Impurities are removed using a tank filled with granite cubes called ...
*
Grainer process
The Grainer evaporation process is a method of producing salt.
This method uses shallow open pans with steam-heated immersion coils to evaporate the brine into salt.
Sometimes it is paired with a partial-vacuum, to speed evaporation.
See also
...
*
History of salt in Middlewich
Middlewich, a town in northwest England, lies on the confluence of three rivers – the Dane, the Croco and the Wheelock. Most importantly for the history of salt making, it also lies on the site of a prehistoric brine spring.
Following the R ...
*
Lion Salt Works
The Lion Salt Works is the last remaining open pan salt works in Marston, near Northwich, Cheshire, England. It closed as a work in 1986 and is now preserved as a museum.
History
John Thompson Junior and his son Henry Ingram Thompson, a membe ...
*
Saline Luisenhall
Saline may refer to:
* Saline (medicine), a liquid with salt content to match the human body
* Saline water, non-medicinal salt water
* Saline, a historical term (especially US) for a salt works or saltern
Places
* Saline, Calvados, a commune ...
*
Salt in Cheshire
Cheshire is a county in North West England. Rock salt was laid down in this region some 220 million years ago, during the Triassic period. Seawater moved inland from an open sea, creating a chain of shallow salt marshes across what is today the ...
*
Salt Museum, Northwich
The Weaver Hall Museum and Workhouse, Northwich, Cheshire, records the social, cultural and industrial history of west Cheshire. It was formerly known as the Salt Museum, reflecting its early focus on the history of salt extraction, a local ind ...
*
Seawater greenhouse
A seawater greenhouse is a greenhouse structure that enables the growth of crops and the production of fresh water in arid regions which constitute about one third of the earth's land area. This in response to the global water scarcity and peak ...
References
{{DEFAULTSORT:Open Pan Salt Making
Industrial processes
Salt production