Minerals: Table salt. Abstract: “extraction and use of table salt What is table salt definition

STATE (REGIONAL) EDUCATIONAL INSTITUTION

ADDITIONAL CHILDREN'S EDUCATION

"CHILDREN'S ECOLOGICAL AND BIOLOGICAL CENTER"

Geological Association "Amethyst"

Section: “Minerals”

Abstract on the topic:

"EXTRACTION AND USE

COLD SALT"

Performed: 8th grade student

Protsenko Ekaterina Andreevna

Supervisor: teacher

additional education

Shepelina O. G.

Lipetsk, 2010

Introduction 3

§ 1. General characteristics of table salt 4

§ 2. Methods of extraction and use of salt in the history of the development of different states 8

§ 3. Salt mines of Russia 17

§ 4. The importance of table salt for living organisms.

Its economic use 23

Conclusion 27

References 28

Introduction

Among all the salts, the most important is the one

which we simply call salt.

A.E.Fersman

Table salt, familiar to every person in the modern world, plays a huge role in nature and the life of living organisms. Now none of us in ordinary life pays special attention to it, and it is difficult to imagine that in former times they worshiped it, valued it like gold, and went on long journeys in search of it. In this work I would like to remind you of the importance, and sometimes even the necessity, of ordinary table salt.

Goal of the work– consider and analyze the extraction and use of table salt.

Tasks:

1. characterize table salt,

2. show the methods of extraction and use of salt in the history of the development of different states,

3. consider the salt mines of Russia,

4. indicate the meaning and identify areas of use of salt by humans.

To make our abstract more interesting, we will try to provide it with photographs and, for greater clarity, create a series of diagrams and maps, which we will also place in the text.

§ 1. General characteristics of table salt

There are only about 100 minerals and varieties on our planet that can be called salts. Table salt is the No. 1 salt, both in distribution in nature and for human life. Table or rock salt is made up of the mineral halite (NaCl).

The name of the mineral comes from the Greek. "gallos" - sea salt.

Pure halite is transparent and colorless (Fig. 1). Inclusions and impurities can color it red (iron inclusions), gray (organic matter) and yellow (sulfur, some iron oxides) tones. When exposed to radioactive radiation, halite turns blue. The mineral has a colorless or white streak and a glassy luster.

It usually occurs in the form of dense, fine-grained Fig.1. Halite (2 cm) on plaster

dense masses, much less often in the form of cubic crystals.

The mineral halite is very brittle, its hardness is 2 – 2.5. It dissolves easily in water at any temperature. Has high thermal conductivity. The diagnostic sign of halite is a salty taste. In addition, if a solution of silver nitrate is added to an aqueous solution of halite, the formation of a dense precipitate of silver chloride AgCl can be seen.

The mineral forms massive clusters.

Halite is widespread. Occurs in the form of layers or salt domes. Salt layers do not come to the surface due to the high solubility of the mineral; they are opened by wells or mines. Halite is the main salt component of oceanic and sea waters, as well as salt lakes and highly mineralized groundwater. It can be found in layers of sedimentary rocks among other minerals - products of water evaporation - in drying estuaries, lakes, and seas. The sedimentary layer is up to 350 m thick and extends over vast areas. For example, in America and Canada, underground salt deposits extend from the Appalachian Mountains west of New York through Ontario to the Michigan basin.

Halite deposits are the main source of table salt, which is used directly as food, is the main component in food preservation, and is used in technology as a raw material for the production of hydrochloric acid and other substances.

For salt deposition, a hot (for rapid evaporation of water saturated with salt) and dry (so that crystallization is not prevented by precipitation and high air humidity) climate is required. This is a subtropical climate of deserts and semi-deserts (arid zone).

Halite, or table salt, is formed:

1. in sea bays that have poor connections with the sea, in lagoons;

2. in the sea coastal sands of low-lying plains (sebkha). Salt water, falling on the surface of the sand, seeps into it. Over time, the pure water evaporates, and the precipitated salt remains in the sand and crystallizes. Repeating itself over and over again, this process contributes to the accumulation of salt in the sand and the formation of entire salt-bearing layers;

3. in lakes with few inflowing rivers, with rapid evaporation of water, they are also sources of salt accumulation. These are mainly drying (desert) lakes in areas with low rainfall and hot seasons. Soda can also accumulate in such lakes.

It should be noted that the main industrial accumulation takes place in sea bays and lagoons and, to a lesser extent, in lakes.

Halite crystals, found in some stagnant salt lakes and reservoirs not subject to waves and storms, can form funnel-shaped skeletal crystals (dendrites). A funnel is one crystal grown from one embryo, which forms on the very surface of the reservoir and grows only from below and from the sides - where it comes into contact with the feeding solution. As the crystal grows, it becomes hollow and floats like a boat on the surface of a supersaturated aqueous solution.

Since the solubility of halite is almost independent of temperature, evaporation acts alone: ​​supersaturation is achieved in the surface layer of the salt solution, and crystal nuclei appear in it. And since the solution is motionless, the funnel grows into a kind of dendrite.

Here's another example. A.E. Fersman describes his observations in the Karakum Desert. After a heavy night rain, the next morning the clayey surfaces of the shores are suddenly covered with a continuous snow cover of salts - they grow in the form of twigs, needles and films, rustling underfoot... but this continues only until noon - a hot desert wind rises, and its gusts dissipate within a few hours salt flowers.

However, the most wonderful stone flowers can be seen in the polar regions. Here, over the course of six cold months, mineralologist P. L. Dravert observed remarkable formations in the salt brines of Yakutia. In cold salt springs, the temperature of which dropped 25° below zero, large hexagonal crystals of the rare mineral hydrohalite appeared on the walls. By spring they crumbled into powder of simple table salt, and by winter they began to grow again.

Rock salt is usually found in ancient, shriveled sea basins. Back in 1715, the scientist Halley raised the question of why the sea is salty; he tried to give an answer, quite rightly trying to find it in the past fate of water. Indeed, over the long history of its appearance on the surface of the Earth, the water of the oceans managed to produce enormous chemical work. Many times it made its constant cycle on the surface of the earth, washing away everything that is easily dissolved, sorting it by specific gravity, accumulating poorly soluble, stable compounds at the bottom of its pools. The complex life of organisms again extracted some of these compounds without affecting others, and thus, throughout the entire geological past, colossal quantities of various salts accumulated in the mass of surface waters. This process of enrichment with salts continues to this day, and millions of tons of dissolved substances are carried with them by rivers every year.

Experts have calculated that if the water of all seas and oceans suddenly evaporated, the salt accumulated in the sediment would be enough to build a wall 1 m thick and 280 m high, which would encircle our planet along the equator.

Huge deposits are not only approximately horizontally lying layers of varying thickness. Sometimes salt deposits have a dome shape: their bases rest at a depth of 5–8 km, and their peaks rise to the earth’s surface, sometimes even protruding from it. Domes are formed as follows. At high temperatures and due to high pressure in the bowels of the Earth, salt becomes plastic. It expands and squeezes upward. The salt is introduced into the overlying rocks.

Salt domes occur in weakened areas of the earth's crust, particularly where faults intersect. The dome consists of a salt massif (stock) and a subsalt structure formed by rocks raised above it. Large salt domes are known in many areas of the globe. For example, Tajikistan has some of the highest salt domes, one of which rises to a height of 900 m. It is called Khoja-Mumyn (Salt Mountain) and is located near the city of Kulyab.

Depending on the conditions of salt occurrence and its origin, several varieties are distinguished:

Self-sedimented salt (Fig. 3), which forms at the bottom of closed water basins in the form of layers in countries with a hot and dry climate.

Rice. 3. Lake Baskunchak is one of the largest deposits of self-sedited salt

3. Volcanic salt is sublimates of volcanoes.

4. Efflorescences are films and deposits on the surface of the earth in steppe and desert areas.

According to the extraction method, salt is also divided into several types:

1. Stone. It is mined by mining using underground mining.

2. Self-sedimented salt or lake salt, mined from layers at the bottom of salt lakes

3. Garden salt is obtained by evaporation or freezing from the water of estuaries and lakes.

4. Evaporated salt is obtained by evaporation from groundwater or dissolving rock salt, followed by pumping out the solution, which is subsequently evaporated.

Other methods of producing salt are known, but they are not very widespread. For example, in Yakutia (Russian Federation) at the Kempendyai deposit, salt from underground sources is precipitated using low temperatures, which no one else does in the world.

As experts note, the cheapest salt is obtained using cage and self-planting technologies, the most expensive is obtained using the vacuum-evaporation method of production.

§ 2. Methods of extraction and use of salt

in the history of the development of different states

When a person first found salt and seasoned his food with it, no one knows. Only one thing is clear: salt began to be mined many millennia before our chronology, and salt mining was one of the most ancient. At first, people used natural salt springs and lake brines, then moved on to boiling down salt and, finally, to extracting rock salt from the bowels of the earth. After all, salt is absolutely necessary for humans, necessary for all animals and plants. The main thing is not its taste, but the role that sodium chloride plays in all living organisms.

The Celts were among the first to obtain salt from brine. In the 1st millennium BC. e. they extracted it from salt springs in many areas of Germany. The Celts poured brine onto hot stones, the water evaporated, and the salt remained on the stone in the form of a crust. Later they began to build brick and tower-like structures with a scaffold of poles and stone slabs under which a fire was built and brine was poured on top of these slabs. After a sufficient amount of salt had settled, the scaffolding was dismantled and the salt was scraped off. Slabs unsuitable for further use were piled up. Now scientists find a large number of similar slabs in Lorraine, a region of Germany, in the valley of the Sey River. In this swampy area with ancient saltworks, called Sei by the Celts, which means “salt water”, the abandoned remains of broken bricks form entire brick “mountains”, the volume of which reached almost 2 million m 3.

This was a grueling and time-consuming method of extraction, so the Celts tried to find a new way to evaporate the brine to obtain salt in large quantities. In the Salt Museum in Bad Nauheim, contemplating the exhibits today, one can only be amazed at how they managed to achieve this.

Initially, the brine settled for some time in specially constructed dams. At the same time, due to the evaporation of water, a more concentrated brine was formed, it evaporated faster, and less firewood was required. This process was carried out in a large clay cauldron, under which a fire burned between two rows of bricks. They were installed obliquely and at some distance from each other. Thus, air flowed evenly from both sides to the fire, the flame was concentrated under the boiler, creating a high heat. It was a simple and rational method, showing how excellent the Celts were with fire and water two and a half thousand years ago.

The brine was evaporated until it thickened, then it was poured into small crucibles and heated until its contents crystallized into a dense mass. Finally the crucible was broken, and a “salt cap” appeared. This form, invented by the Celts and existing almost until our time, was a well-known trade item.

The ancient Romans extracted salt this way. They collected saturated brine from natural sources and evaporated it over a fire.

The first of the great Roman roads, Via Salaria ("Salt Road"), was built to transport the products of the salt works throughout the peninsula. The Roman government did not have a monopoly on the sale of salt, but, if necessary, actively intervened in regulating prices.

Periodically, prices for salt were reduced in Rome - a gift to the plebeians. It was “given” when the government needed popular support. For example, Emperor Augustus, on the eve of the decisive battle with Mark Antony and Cleopatra, distributed salt and olive oil for free. And as a result, he won.

To raise money for the Punic Wars (264-146 BC), Rome masterfully manipulated prices. In the capital, salt remained cheap, but in other places the price depended on the distance to the saltworks.

Salt was of exceptional military importance. Both soldiers and horses needed it. The special ration of salt that every Roman soldier received was called salarium argentum and became the forerunner of the English word salary. The Latin word sal became solde (“to pay”) among the French, and soldier (“soldier”) came from it. And our salads (salad - “salty”) also came from the Romans, since they always salted vegetables. And even salt was added to the wine for preservation (there were no bottle caps then).

On the plebeian table, white crystals stood in a simple sea shell; at a patrician feast - in an elaborate silver salt shaker. And since salt symbolized bonds of friendship, its absence from the banquet table was interpreted as an unfriendly act.

Powdered salt is also mentioned in Chinese sources dating back to the 7th century. BC. Salt production (Fig. 4) was of political importance in ancient China, since salt was always the most important source of income. In the 2nd century. BC e. Rice. 4. Salt production in China

The Chinese government nationalized salt production.

The most common salt in China was sea salt, accounting for 76% of total production; salt obtained from deep sea water - 16.5%; salt from salt lakes - 5.4%; mineral salt - 1%; salt obtained as a by-product of gypsum extraction - 0.4%.

The salt production process was quite complex and required high skill. The most primitive method of obtaining salt was to repeatedly spray burning wood with sea water and then, after burning it out, separating the salt from the ashes. Salt was also produced by simply evaporating seawater in the sun in a flat container. During this evaporation, a little salt was thrown into the water, necessary for further crystallization. The salt was then collected and purified.

Another method was to boil seaweed that had previously been dried in the sun. If drying salt in the sun was difficult, then sea water was boiled in large tanks. Millet chaff and soap bean pods were thrown into boiling water. This helped eliminate calcium sulfate impurities. When the salt concentration in the water was low, a biological purification method was used, in which “wood splitting worms” (a certain type of crustacean) were placed in the water, removing impurities by digesting them.

Salt was collected on the seashore when the tide went out and the remaining moisture evaporated in the sun. A more complex method was also used. Deep holes were dug and covered with reed mats with a layer of sand placed on them. When the tide came in, seawater would seep through the sand mats, which acted as a filter. At low tide, sea water was scooped out of the pits with ladles and poured into special dishes left in the sun. After the water evaporated, the salt was collected. Drying was slow, but this was beneficial because the time allowed the anaerobic bacteria present in seawater to convert the calcium sulfate into calcium sulfide, which precipitated as a “black slush” that could be easily separated from the pure salt. Since the Chinese do not like wasteful expenses, calcium sulfide was used for medicinal purposes as an emetic and as a remedy against insect bites, ringworm, scabies, etc.

Since the Han Dynasty, deep drilling has been carried out to extract salt from sea water, the deposits of which were in the western parts of China (Sichuan). At the same time, natural gas was obtained as a by-product, which was used to heat containers with sea water, from which the salt was evaporated.

All centers of civilization on the American continents arose where there was access to salt. Salt springs were located in close proximity to Cusco. In Colombia, nomadic tribes founded their first permanent settlements near natural salt licks. The highland Chibcha tribe became dominant because its men were the best salt workers. By the way, this tribe had an interesting custom: twice a year, in order to honor the gods, they refrained from eating salt.

The Aztecs did not have their own salt licks and during the hard times of war they obtained salt by evaporating it from urine. And the people of Honduras used the ocean instead of urine. They dipped hot sticks into the surf and cleaned off the white grains.

Salt-rich countries were and are proud of this fact to this day. The salt-mining region in Bolivia attracts tourists with a hotel built entirely from salt.

On the map of Europe, places rich in salt retain in their names echoes of medieval efforts to extract the much-needed product. Salt City is the Austrian city of Salzburg. And the city of Tuzla in Bosnia (from the Turkish tuz - salt) reminds not only of the main fishery, but also of Turkish rule.

We can say with confidence that rock salt was of great importance not only in the economic, but also in the political life of peoples: it served as an object of trade and exchange, a source of replenishment of the treasury. Salt became the cause of bloody wars, civil unrest and riots.

Several thousand years ago, in the countries of the East, in China, Japan and India, salt began to be subject to duties and taxes. Later, taxes on salt were introduced in almost all countries of Western Europe and Rus'. In the summer of 1648, a salt riot broke out in Moscow and lasted three days. It served as an impetus for unrest in Solvychegodsk, Ustyug Veliky, Solikamsk. In the 16th century A real armed uprising broke out in the French port of La Rochelle, through which salt trade was carried out with many overseas states. In the Middle Ages, the uprising of Chinese peasants, outraged by salt taxes, lasted 9 years.

In the 19th century, salt money, bars equivalent to gold, were introduced into circulation in Ethiopia. In China, during the life of M. Polo, there were hallmarked salt coins.

Until recently, salting was the main method of long-term food storage. This is why the Egyptians used salt to make mummies. Thanks to the ability of salt to preserve, protect from rotting, and prolong life, many symbolic meanings began to be attributed to it.

The British did without bread, but they brought salt for housewarmings for a long time.

Since salt prevents rotting, it also protects against spoilage. In the early Middle Ages, peasants in Northern Europe learned to save their crops from the poisonous ergot fungus by soaking the grains in a saline solution before sowing.

The Maasai, a tribe of East African nomadic pastoralists, satisfy their need for salt by bleeding cattle and drinking it. However, vegetarian diets rich in potassium often lack sodium chloride. And all historical documents, including those relating to North America of the 17th-18th centuries, testify: at various stages of human development, one rule remains unchanged - agricultural tribes mine or buy salt, while hunting tribes do not.

The first attempts at domestication were probably made before the end of the Ice Age, and even then people knew that animals needed salt. It has been observed that reindeer come to human sites, attracted by the source of salt. People realized that if they had salt, the deer would come constantly, and perhaps they could be tamed. In the end, deer did indeed become a constant source of food for humans, but they never became truly domesticated [...]

Where people ate mainly grains and vegetables, supplemented only by the meat of slaughtered domestic animals, the extraction of salt became a vital necessity. And this, of course, gave sodium chloride enormous economic value. Salt became one of the first items of international trade, its production one of the first industries and, ultimately, the first state monopoly.

The world's resources of table salt are practically inexhaustible. Almost every country has either rock salt deposits or salt water evaporation plants. A colossal source of table salt is the World Ocean itself. One liter of ocean water contains about 26-30 grams of table salt.

Each region of the world has its own salt reserves, which affect the share of salt production (Fig. 5). North America currently produces the most salt, followed by Asia and Europe. Other regions of the world have small shares in salt production.

Rice. 5. Regional structure of salt production in the world (2005), in%

Currently, table salt is mined in more than 100 countries (Fig. 6). Salt production in the world is carried out in various ways, the main of which include four technologies:

1) obtaining sodium chloride in solutions;

2) evaporation of lake and sea salt in the sun;

3) underground mining of rock salt;

4) production of boiled salt using the vacuum method, which is a way to obtain the highest quality products.

The main methods of producing table salt throughout the world should be considered its release in the form solutions and method evaporation in the sun: the share of each of them is about 35%, while the share underground production rock salt accounts for about 30%. It is important to emphasize that the methods for producing sodium chloride in different countries vary greatly, both in the technologies for obtaining the products and in the equipment used.

Looking at the map, we can say that the first places in the production of table salt, according to our data, are occupied by the USA and China, followed by Canada, Australia and India. Russia ranks only 14th in salt production in the world.

In Russia, salt is extracted from a number of deposits in the Caspian region (lakes Elton and Baskunchak), the Urals, Eastern Siberia, in the central and northwestern regions of the European part, both from rock salt deposits and from salt lakes and salt domes. There are large deposits of rock salt in Ukraine and Belarus. Large industrial reserves of salt are concentrated in the lakes of Kazakhstan and the Kara-Bogaz-Gol Bay in Turkmenistan.

The CIS currently has reserves of various types of salt (Fig. 7). The largest percentage of reserves is rock salt.

The need for human consumption of salt for many millennia has posed the most difficult challenges for engineers, forcing them to invent the most bizarre, but at the same time very ingenious machines. Some of the most ambitious public works in history were undertaken to transport salt. Salt production was at the forefront of the development of chemistry and geology. New trade routes were established, alliances were forged, empires grew, and revolutions raged—all for the sake of a substance that fills the oceans, bubbles in springs, forms crusts on the bottoms of lakes, and is found abundantly in most geological rocks close to the surface.

§ 3. Salt mines of Russia

Salt fishing in Rus' obviously dates back to the beginning of its use in the diet of our ancestors. Salt was also used to store skins and food products for future use: vegetables, fish and meat.

Extraction of table salt was carried out in three ways: brittle rock salt; boiling from sea water and groundwater brines. Salt deposits were intensively searched for and developed. The most ancient information about the extraction of rock salt among the Proto-Slavs dates back to the 5th century. BC e. Trade with the West through the Carpathians followed the salt route, along which salt was exported to Scythia from the Galich deposit, known to Herodotus. Salt was also mined near the mouth of the Dnieper. Later, at least from the 11th century, salt was obtained by boiling water from the Black Sea and Azov estuaries in the south and the White Sea in the north. This salt was called "moryanka". For several centuries, on the White Sea coast, sea water was the main source of salt production.

The method of extracting salt from sea water was suggested to man by nature itself. On the gently sloping shores, dunes or sand spits separate estuaries, which communicate with the sea only when the water level is high. In dry and hot climates, water in estuaries rapidly evaporates, and salt is deposited on their banks and bottom. Observing the process of salt deposition, man learned to arrange auxiliary devices for the extraction of salt where climatic conditions allowed this, for which purpose they built pools that communicated with the sea and with each other.

At first, salt production was of a handicraft nature; later, “salt factories” began to be built.

In the XII-XIV centuries. salt mines arise on the Kama, in Staraya Russa, Rostov the Great, Torzhok, Chukhlom, Vologda, Kostroma, Vychegda, Soli-Galitskaya, Gorodets on the Volga, Pereslavl-Zalessky, Balakhna, Ustyug, Galich Mersky, Nerekhta, etc. Written and material documents have been preserved about numerous points of extraction of salty underground water and salt production during this period on the vast territory of the Russian Plain from Pereslavl-Zalessky, Rostov-Yaroslavsky and Balakhna in the south to the Northern Dvina and Pechora in the north, i.e. in the area of ​​distribution and relatively shallow occurrence of salt-bearing rocks. Many Russian cities, when establishing their coat of arms, reflected on it the method of salt production of their region (Solikamsk, Perm province).

Salt boiling brought huge profits to both the state and the monasteries. The Russian tsars favored the monasteries and did not charge them taxes for salt.

Over time, large salt production centers began to emerge, and its technology became more complex. In the 20s XV century In the Kama Cis-Ural region, the Kallinnikov brothers, immigrants from Novgorod, began the construction of salt factories, which later became the property of the Stroganov merchants. This area began to be called Usolie-Kamsky or Solyu-Kamskaya (now the city of Solikamsk).

End of the 16th century was marked by the exploration of Siberia by Russian explorers. Detachments of Cossacks who went in search of “unknown” lands received special instructions to find places where salt water gushes out of the ground and to cut down boilers in those places, since without salt it was impossible to procure food and furs. Initially, explorers developed self-sediment lakes in Western Siberia, known to local nomadic tribes. Later it turned out that in the Irtysh region, the Kulunda steppe and other places, not only salt lakes, but also sulfate and soda lakes are common. As the Russians penetrated into Eastern Siberia, salt factories were also built there.

At the end of the 17th century. The rock salt of Iletskaya Zashchita in the Southern Urals (now the city of Sol-Iletsk, Orenburg region), as well as the Kempendyai saltworks in the Vilyuy basin, were already generally known.

Further development of salt mining continued during the reign of Peter I. He “renewed” the inactive Old Russian salt mines.

The exploitation of salt workers was monstrous, it was aggravated by difficult and harmful working conditions, since primitive production did not provide for the removal of combustion products and steam released from heated brines. Such working conditions remained unchanged until the 19th century without significant changes. Galician, Vychegda, Pomeranian and other salt workers created large-scale production of table salt in the vast expanses of the Russian state, from the Carpathians to the Urals and Siberia, which provided not only the internal needs of the country, but also trade with foreign countries. Table salt has become one of the main Russian exports.

After various measures (expansion, closure, transition to coal fuel, etc.), the following salt mines operated under Catherine II: Bakhmutsky, Vychugotsky, Yenisei (since 1768), Irkutsky, Ledensky, Nenoksky, Nikolsky, Perm, Balakhninsky ( from 1785), Starorusskie (since 1771), Seregovskie, Selenginskie, Spasskie, Torskie, Totemskie, Unskie, Lutskie, Ust-Kutskie and some others. Of the “Pomeranian” varnishes, the following were exploited: Sumskie, Kemskie, Nyukhotskie and Turchasovskie.

On Lake Elton (Kalmyk name Altannor, i.e. Golden Lake), salt mining began in 1747. As a result of the increase in salt production on the lake to millions of poods per year, the export of salt from the previously developed South Astrakhan lakes fell sharply. Over 134 years of continuous operation, more than 513 million pounds of salt were extracted from Lake Elton; the cessation of mining was associated with the construction of the railway to Lake Baskunchak (1855), which from that time until the present day has been the main “salt shaker” of the country.

From the second half of the 18th century, rock salt was mined on Mount Chapchachi (Guryev region). In the Far East in the middle of the 18th century. The Okhotsk salt plant was founded, where sea water was concentrated by freezing, followed by evaporation of the resulting brines. The plant ceased to exist in 1836, and in the middle of the 19th century, the extraction of salt from sea water was practically stopped everywhere.

Lake Baskunchak is a unique creation of nature, a kind of depression at the top of a huge salt mountain, whose base extends thousands of meters into the depths of the earth. The salt on it was removed using ordinary crowbars and shovels by Kyrgyz workers; Salt was delivered to the shore by camels harnessed to carts. And then on oxen - to all ends of the empire.

The first boreholes, which were laid in the early 70s. XIX century mining engineer A.D. Kondratiev, allowed the development of rock salt deposits. The extraction of rock salt began to increase steadily.

By the end of the 19th century, industrial salt production had become widespread.

The total production of table salt in Russia in 1896 reached 82,188,489 poods, of which the share of rock salt was 25%, self-salting 48% and evaporated salt, obtained by evaporating natural salt brines, 27%.

During Soviet times, in 1924, a large fishery was created in the Kara-Bogaz-Gol Bay. During the Civil War, salt mining on Lake Baskunchak fell into decline. The revival of the salt industry began in 1919.

In 1926, the first Crimean salt research station was created in our country in Saki. Later, similar stations that studied salt lakes were organized in the Kulunda steppe and the Lower Volga region. In 1930, the Salt Laboratory of the USSR Academy of Sciences began work in Leningrad, which in 1935 was reorganized into the All-Union Scientific Research Institute of Galurgy.

Scientists such as N.S. made a great contribution to the study of the riches of salt deposits. Kurnakov, V.I. Vernadsky, A.E. Fersman, A.P. Vinogradov, K.B. Kim and many others.

Currently, the natural resources of salt in Russia are practically inexhaustible. The deposits include rock salt deposits, modern self-sediment lakes, and underground brines.

The largest salt deposits in Russia are visible in Fig. 9. Also in the lower left corner of the map there is a diagram that clearly shows us what share of table salt reserves in the CIS falls on Russia and other countries.

If we look at the diagram (Fig. 8), which shows us the main companies producing and supplying salt to the Russian market, it turns out that the majority of all salt in Russia comes from 2 private Russian companies “Bassol” and “Iletsksol”.

25% of Russia's salt has to be purchased abroad.

Rice. 8. Share of companies producing and supplying edible salt

to the Russian market, in%

Rice. 10. Main countries importing salt to the Russian Federation (as of 2006), in%

Rice. 11. Main countries exporting salt to the Russian Federation (as of 2006), in%

It is safe to say that at least one chemical compound is present in a fairly pure form in every home. This - salt or as chemists call it - sodium chloride NaCl.

It is difficult for us to imagine that in the past, in many countries, table salt served as a significant source of replenishment of the treasury and was an important item of trade. Table salt caused bloody wars between neighboring peoples, and due to the prohibitively high taxes imposed on salt, popular uprisings occurred.

In some countries, table salt even played a role. Numerous historical documents indicate that Roman soldiers, and then the crusaders, were often paid in salt.

Table salt is absolutely necessary for the functioning of the human and animal bodies. A lack of this salt leads to functional and organic disorders: spasms of smooth muscles may occur, and sometimes the centers of the nervous system are affected. The daily need for table salt for an adult is 10–15 g. In hot climates, the need for salt increases to 25–30 g. This is due to the fact that sodium chloride is excreted from the body through sweat and more salt must be introduced into the body to restore losses . When working in hot shops and in dry and hot climates, doctors recommend drinking salted water (0.3–0.5% solution of table salt), since salt helps retain water in the tissues.

Table salt serves as a source of formation of hydrochloric acid in the stomach, which is an integral part of gastric juice. The daily amount of gastric juice in an adult reaches 2 liters. Its acidity is characterized by a pH value of 1.5–2.0.

With low acidity, doctors prescribe the patient a weak aqueous solution of hydrochloric acid, and with high acidity, he experiences heartburn and is recommended to take baking soda. It neutralizes excess acid according to the equation:

HCl+NaHCO 3 =NaCl+CO 2 +H 2 O

Food proteins entering the stomach are broken down into individual amino acid components or blocks of these amino acids under the action of the biological catalyst pepsin. From them the protein inherent to a given organism is synthesized. The enzyme pepsin is formed from another enzyme, pepsinogen. Hydrochloric acid is needed to convert pepsinogen to pepsin. With its deficiency in gastric juice, the digestion and absorption of proteins does not occur or occurs to a small extent. Hydrochloric acid is also involved in the formation of the hormone secretin and some other hormones that stimulate the activity of the pancreas.

However, the human or animal body needs sodium chloride not only for the formation of hydrochloric acid in gastric juice. Table salt is included in tissue fluids and blood. In the blood its concentration is 0.5–0.6%.

Aqueous solutions of NaCl are used in medicine as blood-substituting fluids after bleeding and during shock. A decrease in NaCl content in the blood plasma leads to metabolic disorders in the body.

Table salt promotes water retention in the body, which, in turn, leads to increased blood pressure. Therefore, for hypertension, obesity, and edema, doctors recommend reducing the daily intake of table salt. Excess NaCl in the body can cause acute poisoning and lead to paralysis of the nervous system.

Already two thousand years BC. e. The Chinese learned to obtain table salt by evaporating sea water. The method of extracting salt from sea water by evaporation first appeared in countries with a dry and hot climate - in India, Greece, Rome. Later, salt was mined this way in France, Spain, and Crimea.

Anyone who has tasted sea water remembers that it has a bitter taste and bears little resemblance to an aqueous solution of table salt. This means that seawater contains other salts in addition to sodium chloride. The average content (mass fraction, %) of salts in sea water is as follows: NaCl - 77.8, MgCl 2 - 10.9, MgSO 4 - 4.7, K 2 SO 4 - 2.5, CaCO 3, Ca (HCO 3) 2 – 0.3, other salts – 0.2. The bitter taste of sea cart is due precisely to magnesium salts.

Many people know that table salt exposed to humid air becomes damp. Pure sodium chloride is a non-hygroscopic substance, i.e. it does not attract moisture. Magnesium and calcium chlorides are hygroscopic. Their impurities are almost always contained in table salt and thanks to them, moisture is absorbed.

Rock salt layers are quite common in the earth's crust. It is believed that they were obtained as a result of deformation of the earth's crust with layers of sedimentary rocks formed as a result of the evaporation of sea water or salt lake waters. During deformation, rock salt is squeezed upward to form solid salt domes, which usually have a rounded shape in plan and reach several kilometers in diameter. One of these long-explored rock salt deposits is located near Iletsk in the Orenburg region. The salt dome of this deposit extends 2 km in length, 1 km in width and also goes 1 km deep.

Table salt is the most important raw material of the chemical industry. Soda, chlorine, hydrochloric acid, sodium hydroxide, and metallic sodium are obtained from it.

When studying the properties of soils, scientists found that, being saturated with sodium chloride, they do not allow water to pass through. If the bottom of the reservoir is covered with a layer of soil impregnated with NaCl, then water leakage does not occur.

Chemists know well that by mixing finely crushed ice with table salt you can get an effective solution. For example, a mixture of 30 g of NaCl per 100 g of ice is cooled to a temperature of -20 0 C. This occurs because an aqueous solution of table salt freezes at subzero temperatures. Consequently, ice, having a temperature of about 0 0 C, will melt in such a solution, removing heat from the environment. This property of a mixture of ice and table salt can also be successfully used by housewives.

Edible table salt is a universal mineral product that has been widely used in cooking, medicine, cosmetology and animal husbandry since ancient times.

The substance is crushed transparent crystals with a pronounced taste and odorless. Depending on the purity, in accordance with GOST R 51574-2000, four grades are distinguished: extra, highest, first and second.

Salt can be finely or coarsely ground, and the substance may contain various additives (iodine and other minerals). They give colorless crystals a grayish, yellow or even pink tint.

The daily requirement of salt for a person is 11 grams, that is, approximately one teaspoon. In hot climates the norm is higher - 25-30 grams.

Nutritional value of salt:

Table salt is necessary for the proper functioning of any body, but it is very important to follow the recommended dosage. A deficiency or excess of a substance can cause significant harm to health. Let's figure out why NaCl is useful and harmful, how it is produced and where it is used.

Chemical composition of table salt

The formula for table salt is known to every schoolchild - NaCl. But you will not find absolutely pure sodium chlorine either in nature or on sale. The substance contains from 0.3 to 1% of various mineral impurities.

The composition of table salt is regulated by GOST R 51574-2000, which we have already mentioned above. Standards:

Indicator name	Extra	Top grade	First grade	Second grade
Sodium chloride,%, not less	99,70	98,40	97,70	97,00
Calcium ion,%, no more	0,02	0,35	0,50	0,65
Magnesium ion,%, no more	0,01	0,05	0,10	0,25
Sulfate ion,%, no more	0,16	0,80	1,20	1,50
Potassium ion,%, no more	0,02	0,10	0,10	0,20
Iron(III) oxide,%, no more	0,005	0,005	0,010
Sodium sulfate,%, no more	0,20	Not standardized
Insoluble residue,%, no more	0,03	0,16	0,45	0,85

According to the same GOST, salt is a crystalline bulk product without impurities, with the exception of those associated with its production. Sodium chlorine has a salty taste without any foreign flavors. The highest, first and second grade salt may contain dark particles within the content of iron oxide and water-insoluble residue.

Production of table salt

Methods for extracting sodium chloride have remained virtually unchanged since ancient times, and the substance is produced in almost every country. Let's name the main methods:

• Evaporation in special tanks of sea water. In this case, the composition usually contains many useful elements, including iodine.
• Extracted from the bowels of the earth in quarries and mines - such a substance contains almost no moisture or impurities.
• Washing and evaporating the brine solution thus produces “Extra” grade salt, which has the highest degree of purification.
• Collected from the bottom of salt lakes, self-salt is obtained, which, like sea salt, contains many mineral elements necessary for organisms.

Types of salt

Today there are many types of salt. Among them there are, one might say, classic and exotic. The first ones have long been included in our diet. They have long been used to this day in cooking and creating various medicines and cosmetics:

• Rock salt is ordinary salt without any special impurities.
• Iodized salt is sodium chlorine, which is artificially enriched with iodine; it is very popular in regions where people suffer from iodine deficiency.
• Fluoridated salt - enriched with fluoride is good for teeth.
• Dietary salt has a reduced sodium content, which is why it has a slightly different taste.

Exotic types of salt are used in different cuisines of the world, including Indian volcanic salt, Himalayan pink salt, French smoked salt and many others. Such products differ in shades and the presence of specific flavors.

Beneficial features

Salt is not produced by the body on its own, but is very important in metabolic processes. Chlorine is needed for the synthesis of hydrochloric acid in the stomach, as well as other substances that are responsible for the breakdown of fat. And sodium ensures the correct functioning of muscles and the nervous system, it affects the condition of bones and the absorption of nutrients by the large intestine.

Salt is involved in metabolic processes at the cellular level, thanks to which tissues receive the required amount of elements. The sodium-potassium compound is responsible for the penetration of amino acids and glucose through the cell membrane.

SALT– sodium chloride NaCl. Moderately soluble in water, solubility depends little on temperature: the solubility coefficient of NaCl (in g per 100 g of water) is 35.9 at 20 ° C and 38.1 at 80 ° C. The solubility of sodium chloride is significantly reduced in the presence of hydrogen chloride, sodium hydroxide , salts – metal chlorides. Dissolves in liquid ammonia and enters into exchange reactions. The density of NaCl is 2.165 g/cm 3, the melting point is 800.8° C, the boiling point is 1465° C.

They used to say: “Salt is the head of everything, without salt and life is grass”; “One eye on the police (where the bread is), the other on the salt shaker (salt shaker),” and also: “Without bread it’s not satisfying, without salt it’s not sweet”... Buryat folk wisdom says: “When you’re going to drink tea, put a pinch in it salt; it makes food digest faster and stomach diseases will disappear.”

It is unlikely that we will know when our distant ancestors first tasted salt: we are separated from them by ten to fifteen thousand years. At that time there were no utensils for cooking; people soaked all plant products in water and baked them on smoldering coals, and roasted meat impaled on sticks in the flames of a fire. The “table salt” of primitive people was probably ash, which inevitably got into food during its preparation. The ash contains potash - potassium carbonate K 2 CO 3, which in places far from seas and salt lakes has long served as a food seasoning.

Perhaps one day, in the absence of fresh water, meat or roots and leaves of plants were soaked in salty sea or lake water, and the food turned out to be tastier than usual. Perhaps people hid the meat they had harvested for future use in sea water to protect it from birds of prey and insects, and then discovered that it acquired a pleasant taste. Observant hunters of primitive tribes could notice that animals love to lick salt licks - white crystals of rock salt protruding here and there from the ground, and tried adding salt to their food. There could be other cases of people's first acquaintance with this amazing substance.

Pure table salt, or sodium chloride NaCl, is a colorless, non-hygroscopic (does not absorb moisture from the air) crystalline substance, soluble in water and melting at 801° C. In nature, sodium chloride occurs in the form of a mineral halite– rock salt. The word "halite" comes from the Greek "halos", meaning both "salt" and "sea". The bulk of halite is most often found at a depth of 5 km below the earth's surface. However, the pressure of the rock layer located above the salt layer turns it into a viscous, plastic mass. “Floating up” in places of low pressure of the covering rocks, the layer of salt forms salt “domes” that come out in a number of places.

Natural halite is rarely pure white. More often it is brownish or yellowish due to impurities of iron compounds. Blue halite crystals are found, but very rarely. This means that for a long time in the depths of the earth they were in the vicinity of rocks containing uranium and were exposed to radioactive radiation.

In the laboratory you can also obtain blue crystals of sodium chloride. This does not require radiation; you just need to heat a mixture of table salt NaCl and a small amount of sodium metal Na in a tightly closed vessel. The metal can dissolve in salt. When sodium atoms penetrate a crystal consisting of Na + cations and Cl – anions, they “complete” the crystal lattice, occupying suitable places and turning into Na + cations. The released electrons are located in those places in the crystal where the chloride anions Cl –? . Such unusual places inside the crystal, occupied by electrons instead of ions, are called “vacancies”.

When the crystal cools, some vacancies combine, which is what causes the blue color to appear. By the way, when a blue salt crystal is dissolved in water, a colorless solution is formed - just like ordinary salt.

Greek poet Homer (8th century BC), who wrote Iliad And Odyssey, called table salt “divine.” In those days, it was valued more than gold: after all, as the proverb said, “you can live without gold, but you cannot live without salt.” Military clashes occurred over rock salt deposits, and sometimes salt shortages caused “salt riots.”

On the tables of emperors, kings, kings and shahs there were salt shakers made of gold, and they were in charge of a particularly trusted person - the salt shaker. Soldiers were often paid in salt, and officials received salt rations. As a rule, salt springs were the property of rulers and crowned heads. In the Bible there is an expression “drinking salt from the king’s palace,” meaning a person receiving support from the king.

Salt has long been a symbol of purity and friendship. “You are the salt of the earth,” Christ said to his disciples, meaning their high moral qualities. Salt was used during sacrifices, newborn children among the ancient Jews were sprinkled with salt, and in Catholic churches, during baptism, a crystal of salt was placed in the baby’s mouth.

It was the custom of the Arabs, when approving solemn agreements, to serve a vessel with salt, from which, as a sign of proof and guarantee of constant friendship, the persons who entered into the agreement - the “covenant of salt” - ate several grains of it. “To eat a peck of salt together” – among the Slavs it means to get to know each other well and become friends. According to Russian custom, when they bring bread and salt to guests, they thereby wish them health.

Table salt is not only a food product, but has long been a common preservative; it was used in the processing of leather and fur raw materials. And in technology it is still the starting material for the production of almost all sodium compounds, including soda.

Table salt was also part of the most ancient medicines; it was credited with healing properties, cleansing and disinfecting effects, and it has long been noted that table salt from different deposits has different biological properties: the most useful in this regard is sea salt. IN Herbalist, published in Russia in the 17th century, it is written: “Two essences of salt, one was dug from the mountain, and the other was found in the sea, and which is from the sea, that lutchi, and besides sea salt, that lutchi, which is white.”

However, when consuming salt, you must observe moderation. It is known that the average European daily absorbs up to 15 g of salt with food, while the average Japanese consumes about 40 g. It is the Japanese who hold the world championship in the number of patients with hypertension - a disease, one of the reasons for which is that in the body retains more fluid than he needs. Cells swell from its excess, compress blood vessels, so blood pressure rises, which causes the heart to work overload. It also becomes difficult for the kidneys, which cleanse the body of excess sodium cations.

No plant can grow on soil covered with salt; salt marshes have always been a symbol of barren and uninhabited land. When the ruler of the Holy Roman Empire, Frederick I Barbarossa, destroyed Milan in Italy in 1155, he ordered that the ruins of the defeated city be sprinkled with salt as a sign of its complete destruction... For different peoples at all times, scattering salt meant inviting trouble and losing health.

In ancient times, people used several methods for extracting table salt: natural evaporation of sea water in “salt ponds”, where sodium chloride NaCl - “sea” salt, precipitated, boiling water from salt lakes to obtain “evaporated” salt, and breaking out “rock” salt in underground mines. mines. All these methods produce salt with impurities of magnesium chloride MgCl 2 6 H 2 O, potassium sulfates K 2 SO 4 and magnesium MgSO 4 7H 2 O and magnesium bromide MgBr 2 6H 2 O, the content of which reaches 8–10%.

In sea water, on average, 1 liter contains up to 30 g of various salts, table salt accounts for 24 g. The technology for producing sodium chloride NaCl from sea and lake water has always been quite primitive.

For example, at the end of the “Bronze Age” - three, three and a half thousand years BC - ancient salt makers doused logs with sea water, and then burned them and extracted salt from the ashes. Later, salt waters were evaporated on large baking sheets, and animal blood was added to remove impurities, collecting the resulting foam. Around the end of the 16th century. salt solutions were purified and concentrated by passing through towers filled with straw and bush branches. Evaporation of the salt solution in air was also carried out in a very primitive way, by pouring the brine over a wall made of bundles of brushwood and straw.

Salt making, the oldest of the chemical crafts, arose in Rus', apparently, at the beginning of the 7th century. The salt mines belonged to the monks, who were favored by the Russian tsars; they were not even charged a tax on the salt they sold. Salt boiling brought huge profits to the monasteries. Brines were extracted not only from lakes, but also from underground salt springs; boreholes that were built for this purpose in the 15th century. reached a length of 60–70 m. Pipes made of solid wood were lowered into the wells, and the brines were evaporated in iron pans on a wood firebox. In 1780, more than one hundred thousand tons of salt were boiled in Russia in this way...

Currently, table salt is extracted from the deposits of salt lakes and deposits of rock salt - halite.

Table salt is not only an important food seasoning, but also a chemical raw material: sodium hydroxide, soda, and chlorine are obtained from it.

Lyudmila Alikberova

Several centuries ago, common salt was one of the most valuable commodities in world trade. In modern times, the relative value of salt has decreased markedly compared to other minerals. Oil, gas, and other resources filled the information space, and mentions of salt became quite rare. Meanwhile, in all spheres of human activity, salt continues to play a vital and difficult to replace role.

The meaning of salt

You may hear different names used for salt. The most commonly mentioned are rock salt and table salt. If we omit some nuances, which we will talk about below, then both rock and table salt are the same sodium chloride (NaCl). The importance of this chemical compound cannot be overestimated.

Naturally, first we should talk about rock or table salt as a food additive necessary for the human body. Normal functioning of the human body is simply impossible without rock salt. For example, gastric juice contains a significant amount of hydrochloric acid, and the main raw material for its production by the body is salt. Ions of various substances are involved in the transmission of impulses along nerve fibers and in the work of muscle tissue. This includes sodium ions, the main supplier of which is salt used in food. In addition, it contains, in the form of impurities, manganese, chromium, iron - trace elements that are absolutely necessary for humans.

As for industry, it is difficult to find an industry that is not directly or indirectly dependent on processed products obtained from ordinary salt itself. This is, for example, sodium metal, which is widely used in nuclear energy and aircraft manufacturing. It is impossible to do without salt in the production of soap and in the dyeing business. NaCl is also a raw material for the chemical industry. Chlorine, various sodas, caustic soda, hydrochloric acid - people get all this from rock salt.

Livestock farming, agriculture and municipal services, and the drilling industry will not be able to function without ordinary salt.

In percentage terms, the approximate distribution of all mined rock salt looks like this:

• the majority, about 60%, is consumed by the chemical industry as raw materials;
• approximately 25% is used in the food industry;
• the remaining 15% of consumption comes from utilities, agriculture and other areas of activity.

World consumption of rock salt is growing every year. Over the past seven years, the growth in production, and, consequently, consumption, has amounted to 5%.

History of rock salt mining.

The history of rock salt mining goes back not even centuries - millennia!

The sea coast of modern Bulgaria - dome-shaped adobe ovens were discovered here, in which salt was evaporated. This saltworks dates back to the fourth millennium BC. Ancient sources contain references to salt mining in the 5th century BC. Salt mines dating back to the Bronze Age have been found by archaeologists in Austria.

Throughout all these millennia, the work of a salt miner has been exceptionally difficult. A wheelbarrow, a pickaxe and a shovel are the tools that were used to mine rock salt. And only at the beginning of the twentieth century mechanization came to the salt fields.

In Russia, the first mention of salt fishing dates back to the 11th century. At the end of the 17th - beginning of the 18th centuries, salt production in Russia developed very widely. By the 19th century, annual production of rock salt reached 350,000 tons. And by the beginning of the 20th century, more than 1.8 million tons were mined annually in our country.

Now the annual volume of world salt production is approximately 210,000,000 tons, and this volume is constantly growing. The growth of consumption predetermines the need to develop production technology and improve processing. Today there are several ways to industrially produce salt.

Basin method of salt extraction

Huge, practically inexhaustible reserves of salt are contained in the water of the seas, oceans, and salt lakes. This salt is mined using the pool or self-planting method. Natural estuaries are separated from the sea by dunes or spits. In summer, when the weather is hot, the water in the estuaries evaporates intensively, and salt precipitates. Where there are no natural estuaries, artificial pools are built. The pools are filled with sea water. After this, their connection with the sea is stopped, and the evaporation process occurs similarly to natural in estuaries, under the influence of the sun and wind. The precipitated salt is collected technologically. Equipment such as excavators, bulldozers, and, where necessary, hand shovels is used. This technology has remained unchanged for centuries. Mechanization only brought it to the modern industrial level. However, in the total volume of salt produced, this method takes only second place.

Mining fossil salt

In the first place is the extraction of fossil rock salt. Solid salt in the bowels of the Earth is otherwise called “halite”. Underground salt deposits formed hundreds of millions of years ago on the site of ancient seas and oceans. These rocks can be either colorless or snow-white. But more often, impurities color halite in different colors: clay impurities give it a gray color, iron oxides - yellow or red, the presence of bitumen - makes the rock brown.

The development of fossil salt does not depend on the time of year and weather conditions, so more than 60% of world production comes from them. Underground deposits of rock salt can reach depths of 7-8 kilometers, and reach the very surface, forming above-ground domes.

Deposits with a depth of up to one hundred meters are developed by open-pit or open-pit mining. Having removed the top layer of soil and rocks covering the salt deposits, you can begin the direct extraction of salt. The explosive, mechanical method or their combination is used. With the explosive method, holes are drilled in rock salt layers, explosives are placed, and by the force of the explosion, pieces of the salt layer break off from the main mass. In the mechanical method, special equipment is used to destroy the massif: excavators, graders, winches, etc. The open-pit mining method ensures the most complete extraction of minerals, has the lowest cost and the greatest safety. The disadvantages of quarrying are that the mined rock salt is susceptible to contamination by sediments, groundwater, and dust deposits.

The deeper the quarry becomes, the less pronounced the advantages of this mining method become. Especially its profitability. At a certain stage, the profitability of quarrying becomes equal to the profitability of mining using the shaft method. Then, to improve the quality of the extracted salt, they switch to the latter.

When deposits are located at a depth of more than a hundred meters, the mine method is used to extract rock salt. At the moment, the single-horizon method of opening has displaced all others from salt mines. It does not require a large amount of capital work, it is quite simple and versatile. However, with significant deepening of workings, there is a need to organize multi-stage transport lifts and powerful ventilation systems.

A salt mine is a tunnel in the thickness of a salt layer. Chambers extend from it on the sides, from which the main selection of rock salt is made. Each chamber reaches a length of up to 500 meters. The width and height of the chambers are 30 meters each. The chamber system does not require securing excavations. The absence of the need to secure the roof reduces the cost of extracted salt and increases labor productivity. Large mined-out spaces in the chambers make it possible to use mining equipment with high productivity and power. Scraper installations, electric locomotives, road boring machines are widely used in salt mines. The exhausted chambers are successfully used for the safe disposal of industrial waste.

Along with the described advantages, the chamber system also has disadvantages. Large volumes of mined-out spaces lead to ventilation problems. In addition, more than half of the salt reserves remain in the spaces between the chambers (pillars), sometimes up to 70%.

It should be noted that most mining enterprises practice exclusively machine mining. However, in some cases a less advanced drilling and blasting method is used. Drilling pits, laying explosives and subsequent explosive rock fall give much less efficiency and productivity. At the same time, the level of labor safety is significantly lower.

Leaching mining method

The essence of this method is as follows:

• in the explored salt formation, wells of the required depth and in the required quantity are drilled;
• fresh water heated to a high temperature is pumped into the wells;
• this water dissolves the salt;
• the liquid brine solution is pumped to the surface by slurry pumps;
• the salt slurry ends up in special sealed tanks with reduced pressure;
• due to low pressure, intense evaporation of water occurs;
• The salt settled at the bottom of the tanks is crushed by a centrifuge.

Due to its use in low-pressure tanks, this method is also called vacuum. Its advantages include low cost, especially when extracting salt from great depths. The disadvantages are high requirements for the chemical and mechanical stability of pumps due to the aggressiveness of the saline solution.

Explored world salt reserves and deposits

The world's reserves of rock salt are so huge that it is impossible to calculate their exact quantity.

Each cubic meter of water in the world's oceans contains about 27 kilograms of sodium chloride. If all the salt contained in the waters of lakes, seas and oceans is evenly distributed over the surface of the Earth, then the thickness of the salt layer will reach 45-50 meters.

Underground reserves of solid salt, according to the most rough estimates, are at least 3.5-4 * 1015 tons. If current production volumes are maintained, fossil reserves alone will last for at least fifteen thousand years.

In Europe, the largest salt deposits include the German Statfurt basin, the Slavyano-Artemovskoye and Prikarpatskoye deposits in Ukraine. In North America, there are large deposits in the USA (Kansas and Oklahoma), and the Canadian Saskatchewan basin.

On the territory of the Russian Federation there are reserves of table salt, the largest explored in the world.

In first place is Lake Baskunchak in the Astrakhan region. This unique deposit has been known since the 17th century. Its uniqueness lies in the fact that its salt reserves are replenished from the sources that feed the lake. According to geologists, the depth of the salt layers here reaches a record ten kilometers. On Lake Baskunchak, 930,000 tons of table salt are mined per year.

Nearby, in the Volgograd region, there is Lake Elton. There are also significant reserves of table salt.

The Sol-Iletskoye field has been developed in the Orenburg region for a long time. Back in the 18th century, the great Lomonosov examined samples of Iletsk salt. His notes have been preserved, in which he speaks extremely flatteringly about the quality of this salt. Here is located the Iletsksol JSC plant, the largest in Russia (83%) in terms of the volume of underground mining of fossil halites. According to the project, the annual production capacity of the Iletsksol plant is 2,000,000 tons. The salt from the local deposits is of the highest quality. It requires neither purification nor enrichment.

Another large deposit is Usolye, located in Yakutia, near Irkutsk.

In conclusion, I would like to add that there is definitely no threat of a shortage of rock salt to humanity.

	Sodium chloride	Potassium chloride	Calcium chloride	Magnesium chloride	Sodium sulfate	Potassium sulfate	Calcium sulfate	Magnesium sulfate	Insoluble substances	Water
Stassfurt
Stassfurt
Inowraclav
Sumbakovaya
Bakhmutskaya
Perm
Perm