Salt extraction
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Under salt extraction means the removal of certain readily soluble salts from the deposits and the making available for subsequent processing. This mainly concerns the extraction of a salt mixture consisting almost exclusively of table salt (sodium chloride, NaCl) and its processing into table salt . The following three methods are used worldwide for salt production: mining, borehole solution and separation from saline surface waters.
history
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Salt was extracted from brine springs in what is now Saxony-Anhalt as early as the Neolithic and Bronze Age . During the Iron Age ( Hallstatt Period and La Tène Period ), salt pans were created at numerous brine springs and on the coasts. The most important locations in Germany were: Halle (Saale) , Bad Nauheim , Schwäbisch Hall , Werl (Westphalia). These salt pans worked with ceramic boiling vessels that were placed on small clay pillars in the boiling ovens. The remains of these ovens and boiling vessels are called "briquetage" by archaeologists. African tribes still used this form of salt production up to our times. The boiling of brine in pans made of lead or iron was only introduced in Europe in Roman times.
The first German saltworks towns were Bad Reichenhall since 696 and Soest also since the 7th century, Halle (Saale) since 806, Werl since 850, Lüneburg since 956, Einbeck also since the 10th century and Schwäbisch Hall since 1037. The Werl saltworks provided ceased operations before the First World War , as the salt springs brought too little brine to light due to the excavation work for the coal mining in neighboring Hamm .
As a rule, the brine springs were the property of the sovereigns, the boiling operation was leased to Pfänner , who produced the salt commercially and sold it in cooperation. In Halle the Halloren , in Werl the Erbsälzer, had the right (the salt shelf ) to extract and sell salt, as evidenced by the sovereign, into the 19th century. The Erbsälzer received the imperial nobility recognition from the emperor in 1708 on the basis of a document from 1432. The salt was evaporated in large pans made of lead or sheet iron .
"A mile away from the place / in the mountain / there is a salt mine / in which the salt stones / like another Ertz / are hewn out / and thrown into large pits made for them: Then such pits are filled with fresh water / the same for several months / bit the salt stone well melted / and the unclean has settled / stood on the ground; Then you try the water with a piece of wood prepared for it: If you find it too rich in salt / you leave more sweet water on it. When it is found right at the sample / it is carried in wooden ponds in the place of the salt pans in large wooden boxes / which are so high / that such water can furthermore easily be led into the pans. In this Saltzhaus there are four sturdy iron pans / each of which is eight and forty feet long / 34th wide / and 3rd deep. Is each / at all costs / until it is made / posted for three thousand guilders / and may be needed for about ten years / but it must always be mended / and mended / preserved. When to make the pans / so hit 15. Schmid especially on a nail / which is riveted. Such pans have wind ovens / which are about a shoe wide / and six high. All pans are supported by pillars / because of their enormous size. One of the four pans is left to rest for the 7th day / and only boiled in the 3rd and for Jacobi all pans are allowed to freeze for the 3rd week. It should be on the whole Werck / in the Bergwerck / by the Saltzgruben / in forests for wood cutting / for flötzen / in the hall to boil (for which the fuel wood should be brought to the Yhn Kan at low cost /) sampt all craftspeople and felchers / something has to do with this salt work / every day that a thousand people are needed. And should the Saltzwerck / which has already granted a good one over the three hundred years / of the year / over all expenses / bit in the 150,000 guilders surplus. "
During the boiling process, different liquids such as blood, egg white or beer were added to make the impurities foam up.
Fuel resources became scarce from the 16th century. Before boiling , the salt content of the brine was increased by grading . The brine trickled over straw or thorn bushes (usually black thorn ), water evaporated and the salt content in the brine increased. The brine was also cleaned of lime , gypsum and other secondary substances. These, because they are less soluble than table salt, were deposited on the scrub of the graduation tower as gray-brown thorn stones .
The facilities, like the pumping systems and the ever-growing boiling facilities, required a high level of capital expenditure, which could no longer be raised by the Pfänner. In many cases the ruler drew the main profit from taxes on salt production. In his study (2007) on the salt pans “ Brockhausen ” and “ Bad Sooden-Allendorf ”, Leeck presents two options that were common at the beginning of the 16th century: the financing of new technologies by businessmen and by the sovereign. Salt production became a state monopoly at some locations . The Royal Saltworks in Arc-et-Senans formed the essential features of a factory in the 18th century . The Pfänner became wage laborers and the owners of the salt pans became early capitalist employers.
The technology changed around 1955, as it was possible to smash salt-bearing rock under water pressure. At a distance of several hundred meters, shafts are drilled into the salt seams and pipes are laid. Water is pumped down under high pressure. At the foot of the shafts, cracks and fissures form in the rock, which connect the boreholes with one another. This brine process increases the amount of salt obtained from a deposit from five percent to over 40 percent of the existing rock salt. The prime costs drop by 50 percent and the maintenance costs even by over 95 percent.
Mining extraction
In Germany, stone and potash currently in seven salt mines and four potash mined . The quarrying is mostly carried out using the chamber quarrying process, i.e. the rectangular quarrying rooms are supported by permanent pillars made of salt rock. The salt extraction is mainly carried out by drilling and blasting and conveying it away using large, trackless mobile devices. The boreholes are made with a diesel-powered drill carriage and an electro-hydraulic drill drive. Explosives loading vehicles bring mostly loose ammonium nitrate salt mineral into the boreholes pneumatically. The blasted debris is loaded onto a drive shovel loader and transported to the crushing systems, crushed and transported to the conveyor shaft via conveyor belt systems . The shaft hoisting is realized with vessel hoisting systems.
Some exploited old shafts in no longer managed salt domes are used as storage rooms for toxic or radioactive waste.
Brine extraction
Fully saturated brine is required for processing brine into salt. This has a sodium chloride (NaCl) content of 26% or 317.86 g / l at 15 ° C. Natural brine from drilling into underground brine sources is mostly undersaturated and is subsequently saturated by adding solid salt.
Artificial brine is obtained from rock salt deposits through controlled drilling brine as saturated brine. The extraction takes place in so-called caverns , i. That is, a vertical bore is drilled in a salt dome and a funnel-shaped cavity is opened up by introducing fresh water. The raw brine obtained is generally not pure enough for further processing and has to undergo chemical cleaning as part of the salt processing and then be crystallized again in an evaporation process.
Extraction from salty surface water
The extraction of sea salt from salty waters ( coastal waters , salt lakes ) requires an at least seasonally warm, dry climate and takes place in several stages. First, the salt water is pumped into several evaporation ponds connected in series for pre-concentration. The degree of saturation of the brine increases in each stage, so that most of the gypsum is already precipitated. The saturated brine is then pumped into crystallization ponds, in which the final evaporation takes place. Approx. 23 kilograms of sea salt can be obtained from one cubic meter of normal salty sea water . Then the salt processing takes place . Analogous to the extraction from sea water, salt can also be extracted from salt lakes. These usually already contain concentrated salt solutions and often fewer minor minerals than the sea. The Dead Sea has 7.93% NaCl, the Great Salt Lake in the USA even has 15.11% NaCl. In arid areas, seawater desalination plants are used to obtain drinking water . This can result in salt as a by-product, which then has to be processed.
Museums
In places with a salt-boiling tradition, the local museums often have their own departments dedicated to this topic (e.g. House Catoir in Bad Dürkheim , Romanesque House in Bad Kösen or museum.ebensee in Ebensee ). Some museums also deal exclusively with the - mostly historical - local salt works (e.g. the graduation tower in Bad Salzungen and the salt museums in Bad Reichenhall , Bad Sooden-Allendorf , Lüneburg and Soltau ). There are also show mines in places with a salt mining tradition (e.g. in Berchtesgaden and Hallein ). In Halle (Saale) the so-called show boiling has taken place several times a year in the Halloren and Saline Museum since 1969 . The experimental-archaeological “Saltsyderie” on Læsø in the Kattegatt also offers a direct insight into the historical salt-boiling trade .
literature
- A. Leckzik, F. Götzfried, L. Ninane: Sodium chloride and alkali carbonates . Wiley-VCH Verlag, 2005, ISBN 3-527-30768-0 .
- Jean-Francois Bergier: The story of salt . Frankfurt 1989, ISBN 3-593-34089-5 .
- Jean-Claude Hocquet: White Gold. Salt and power in Europe from 800 to 1800 . Klett-Cotta, Stuttgart 1993, ISBN 3-608-91365-3 .
- Hans-Heinz Emons, Hans-Henning Walter: With the salt through the millennia, history of the white gold from prehistoric times to the present . German publishing house for basic industry, Leipzig 1984, DNB 870337211 .
- Thomas Hellmuth, Ewald Hiebl: Cultural history of salt - 18th to 20th century . Publishing house for history and politics, Vienna 2001, ISBN 3-486-56505-2 .
- Journal of Salt History / Annales d'Histoire du Sel / Yearbook for Salt History . Review of the International Commission for the History of Salt (CIHS). Vol. 1 ff. (1993 ff.). Berenkamp, Hall in Tirol.
- Manfred Treml (Ed.): Salt, Power, History . State exhibition 1995 of the House of Bavarian History. Pustet, Regensburg 1995, ISBN 3-7917-1470-8 .
- Friedrich v. Klocke: The patriciate problem and the Werler heir salters . Aschendorffsche Verlagbuchhandlung , Münster 1965, DNB 452455537 .
- Günther Beck : The formation of mountain areas in the salt industry. In: Wolfgang Ingenhaeff, Johann Bair (Hrsg.): Bergbau und Bergeschrey. To the origins of European mines. Hall i. T. / Vienna 2010, pp. 39–58.
- Oliver Haid, Thomas Stöllner : Salt, salt production, salt trade. In: Heinrich Beck, Dieter Geuenich, Heiko Steuer (Hrsg.): Reallexikon der Germanischen Altertumskunde. 2nd Edition. Volume 26, Berlin / New York 2004, pp. 354–379.
Web links
Individual evidence
- ↑ Johannes Lang : History of Bad Reichenhall . 2009
- ↑ Matthäus Merian: Topographia Provinciarum Austriacarum . Frankfurter Kunstverein, Frankfurt am Mayn 1679, p. 319. (full text on Wikisource )
- ↑ Christian Leeck: The introduction of technological innovations in the saltworks of the 16th century . Munich 2007, ISBN 978-3-638-66282-6 .
- ↑ Mining and saline sites for rock salt and potash salt mining sites in Germany. Website of the Association of the Potash and Salt Industry e. V. (VKS)
- ↑ The museum's website with dates.
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