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Open-pan salt making is a method of salt production wherein salt is extracted from brine 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 seawater. [1]
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 groundwater, 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 freshwater and is known as 'controlled brine pumping'. A bastard brine used to be made by allowing freshwater 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 seawater before evaporation. Solar evaporation uses the sun to strengthen and evaporate seawater 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. [2]
This led to three types of salt production, all of which used a variation of the open-pan salt method:
Coastal salt production, involving solar evaporation of seawater, followed by artificial evaporation of salt using the open-pan technique in structures known as 'salterns'. [3]
Inland salt production, using brine from natural brine streams flowing over buried salt deposits that were pumped up from the ground and evaporated using the open-pan technique. [4]
Salt refining, 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. [5]
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, Cheshire, United Kingdom; Royal Saltworks at Arc-et-Senans, Salins-les-Bains, France; [6] Saline Luisenhall, Göttingen, Germany; [7] the Salinas da Fonte da Bica, Rio Maior, Portugal; [8] and the Colorado Salt Works, USA. [9] The two French saltworks at Salins-les-Bains and Arc-et-Senans became a UNESCO World Heritage Site in 1982. [10]
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 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) [11] and later in Northern England. [12]
The Romans introduced small (3 ft square) pans made from lead using wood as a fuel. In Britain they established towns for salt production at Droitwich in Worcestershire, [13] and Nantwich, [14] Middlewich [15] [16] and Northwich [17] in Cheshire. In the early Middle Ages these developed into the 'wich' towns of Cheshire. Small 'wich' houses containing several lead pans to evaporate 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. [18] [19]
By the 17th century, the pans started to be made from iron, firstly in pans 7 ft (2.1 m) by 8 ft (2.4 m). William Brownrigg writing in 1748, in his Book of Common Salt, shows a wood-cut of one of these salt-making pans. [20] 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 40 ft (12 m) wide and 27 ft (8.2 m) long and 1 ft (0.30 m) deep. [21] 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. [22]
These fell into two categories: Smaller fine pans were 35 feet (11 m) and about 25 feet (7.6 m) wide and about 1.5 feet (0.46 m) 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 212 °F (100 °C). 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. [22]
The second larger common or fishery pans were 80 feet (24 m) long x 30 feet (9.1 m) wide x 2 feet (0.61 m) 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 100 and 160 °F (38 and 71 °C) 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. [22]
The following are historical names given to occupations in open pan salt works, primarily in Cheshire, England. [23]
Northwich is a market and port town and civil parish in the unitary authority of Cheshire West and Chester in the ceremonial county of Cheshire, England. It lies in the heart of the Cheshire Plain, at the confluence of the rivers Weaver and Dane. The town is about 18 miles (29 km) east of Chester, 15 miles (24 km) south of Warrington, and 19 miles (31 km) south of Manchester.
Middlewich is a town in the unitary authority of Cheshire East and the ceremonial county of Cheshire, England. It is located 19.2 miles (30.9 km) east of Chester, 2.9 miles (4.7 km) east of Winsford, 5.3 miles (8.5 km) south-east of Northwich and 4.7 miles (7.6 km) north-west of Sandbach. The population at the 2011 Census was 13,595. Middlewich, together with Northwich and Winsford, forms part of the Central Cheshire conurbation, with an estimated 2023 population of 130,000.
A salt evaporation pond is a shallow artificial salt pan designed to extract salts from sea water or other brines. The salt pans are shallow and expansive, allowing sunlight to penetrate and reach the seawater. Natural salt pans are formed through geologic processes, where evaporating water leaves behind salt deposits. Some salt evaporation ponds are only slightly modified from their natural version, such as the ponds on Great Inagua in the Bahamas, or the ponds in Jasiira, a few kilometres south of Mogadishu, where seawater is trapped and left to evaporate in the sun.
Salt, also referred to as table salt or by its chemical formula NaCl, is an ionic compound made of sodium and chloride ions. All life depends on its chemical properties to survive. It has been used by humans for thousands of years, from food preservation to seasoning. Salt's ability to preserve food was a founding contributor to the development of civilization. It helped eliminate dependence on seasonal availability of food, and made it possible to transport food over large distances. However, salt was often difficult to obtain, so it was a highly valued trade item, and was considered a form of currency by many societies, including Rome. According to Pliny the Elder, Roman soldiers were paid in salt, from which the word salary is derived, although this is disputed by historians. Many salt roads, such as the Via Salaria in Italy, had been established by the Bronze Age.
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 until the water had boiled away and salt was left behind. Often, the bulk of the water would be allowed to evaporate in salterns before the concentrated brine was transferred to a smaller briquetage vessel for final reduction. Once only salt was left, the briquetage vessels would have to be broken to remove the valuable commodity for trade.
The Saline Royale 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 to the southwest of Besançon. The architect was Claude-Nicolas Ledoux (1736–1806), a prominent Parisian architect of the time. The work is an important example of an early Enlightenment project in which the architect based his design on a philosophy that favored arranging buildings according to a rational geometry and a hierarchical relation between the parts of the project.
Salins-les-Bains, commonly referred to simply as Salins, is a commune in the Jura department in the Bourgogne-Franche-Comté region in Eastern France. It is located on the departmental border with Doubs, 34.8 km (21.6 mi) to the south-southwest of Besançon. In 2018, Salins-les-Bains had a population of 2,567.
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 other halophiles including algae and bacteria.
A "-wich town" is a settlement in Anglo-Saxon England characterised by extensive artisanal activity and trade – an "emporium". The name is derived from the Anglo-Saxon suffix -wīc, signifying "a dwelling or fortified place".
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.
Middlewich is one of the Wich towns in Cheshire, England.
The Lion Salt Works is the last remaining open pan salt works in Marston, near Northwich, Cheshire, England. It closed as a works in 1986 and is now preserved as a museum.
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 Cheshire Basin. As the marshes evaporated, deep deposits of rock salt were formed.
British Salt Limited is a United Kingdom-based chemical company that produces pure white salt. The company is owned by Tata Chemicals Europe after a buy out from private equity company LDC in April 2010. It is based in Middlewich, Cheshire, employs 125 people, and produces approximately 800,000 tonnes of pure white salt every year.
Warmingham is a village and civil parish in the unitary authority of Cheshire East and ceremonial county of Cheshire, England, on the River Wheelock, 3.25 miles (5.23 km) north of Crewe, 3.25 miles (5.23 km) south of Middlewich and 3.25 miles (5.23 km) miles west of Sandbach. The parish also includes the small settlement of Lane Ends, with a total population of just under 250. Nearby villages include Minshull Vernon, Moston and Wimboldsley.
A seawater greenhouse is a greenhouse structure that enables the growth of crops and the production of fresh water in arid regions. Arid regions constitute about one third of the Earth's land area. Seawater greenhouse technology aims to mitigate issues such as global water scarcity, peak water and soil becoming salted. The system uses seawater and solar energy, and has a similar structure to the pad-and-fan greenhouse, but with additional evaporators and condensers. The seawater is pumped into the greenhouse to create a cool and humid environment, the optimal conditions for the cultivation of temperate crops. The freshwater is produced in a condensed state created by the solar desalination principle, which removes salt and impurities. Finally, the remaining humidified air is expelled from the greenhouse and used to improve growing conditions for outdoor plants.
The history of Northwich can be traced back to the Roman period. The area around Northwich has been exploited for its salt pans since this time. The town has been severely affected by salt mining with subsidence historically being a large issue. A programme of mine stabilisation has recently been undertaken.
The New Cheshire Salt Works Ltd was a salt manufacturer formerly located in Wincham, north east of Northwich in Cheshire, UK. Run by the Stubbs family, it operated between around 1923 and 2006. This is incorrect. The company is still active, see UK Government information https://find-and-update.company-information.service.gov.uk/company/00194522 It produced white or brine salt from naturally occurring underground brine using natural or wild pumping. The salt was extracted by vacuum evaporation and was of a high quality. It was used for human consumption under the brandname "Selva" and in the pharmaceutical industry; New Cheshire was the only British company to supply salt for pharmaceutical use.
Moshio salt (藻塩) is a type of Japanese sea salt made using an ancient method where it is collected using a dried seaweed known as hondawara. The seaweed is believed to confer additional umami flavor to the salt.
The Grozon collieries and saltworks are coal and rocksalt mines located in the Keuperian basin, in the Jura department of Bourgogne-Franche-Comté, in eastern France. They were mined in the communes of Grozon and Tourmont from 1845 to 1944 for the coal and from the 6th to the 20th century for the salt, after an initial period of mining in the Neolithic period and during the Ancient history. The use of coal on site to evaporate the brine enabled the Jura Mining Company to reduce the cost of salt.