Shulou(Shulou.com)11/24 Report--

This article comes from the official account of Wechat: Earth knowledge Bureau (ID:diqiuzhishiju)

In 2011, the nuclear leak caused by the earthquake and tsunami in Japan spread across the country caused by the explosion of the Japanese nuclear power plant, and there was a scramble for salt in the country in case of nuclear radiation contamination of sea salt in Japan.

In 2023, Japan will discharge nuclear contaminated water into the sea, and salt grabbing will occur again in Japan.

Did you eat up the salt you stored last time?

China Salt Group stated: at present, the proportion of China's salt product structure is 87% of well and mineral salt, 10% of sea salt and 3% of lake salt, and the production of well and lake salt is not affected by nuclear pollution in Japan.

Even if the sea salt can not be eaten, the salt produced in the interior of our country is still enough to eat for dozens of lives. In this way, it is not necessary to hoard salt.

China has no shortage of salt as an indispensable material for the human body, which plays a vital role in human society. With the rapid development of chemical industry and the continuous expansion of new fields, there is a great demand for salt all over the world every year. Salt consumption, to a certain extent, can measure the level of industrialization of a country.

"Industrial salt" is known as "the mother of chemical industry"

Basic chemical industrial products made from "industrial salt" have a wide range of uses, ▼.

If divided from the source of raw materials for salt production, salt can be divided into sea salt, lake salt, well salt and rock salt.

Among them, sea salt is extracted from sea water; lake salt is obtained from saltwater lakes; well salt is prepared from natural brine or artificial brine in underground salt mines; and rock salt exists as a solid under the soil. it is formed by inland sea water evaporating over time in a hot climate.

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On the earth, the resource reserves of salt is about 6.4 × 108 million tons, of which the reserves of sea salt is about 4.3 × 108 billion tons, accounting for 70% of the total. Before the nuclear contaminated water is discharged into the sea, we can confidently believe that the salt resources on the earth are inexhaustible.

In addition to sea salt, China's land salt resources are also very rich. Among them, the proven reserves of lake salt resources is 638 trillion tons, and the producing areas are mainly located in Inner Mongolia, Qinghai, Xizang and other places. The reserves of well and mineral salt resources are 43.3 billion tons, which are widely distributed in Sichuan, Hubei, Yunnan and other places.

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However, with the current technology, the proven amount of resources does not mean that it can be fully utilized. The value of salt products is very low, and China's salt lakes are distributed in the western inland, the transportation is inconvenient, far away from economically developed areas, profits can not cover the cost of long-distance transportation.

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In addition, the production of lake salt needs supplementary water, and for every 1 ton of salt produced, 10 cubic meters of water must be replenished, and its production is restricted by water resources. The recovery of rock salt is low, if the mining is improper, it will cause geological disasters. The production of well and mineral salt requires fresh water and a lot of energy.

Nevertheless, according to the data of the National Bureau of Statistics, the basic reserves of salt mines in China are 84.25 billion tons, while the current annual output of raw salt is 97.75 million tons, which is enough for us to mine for hundreds of years, even if the losses in mining are removed.

First of all, let's look at sea salt. Where there is a sea, there are not sea salt resources. Only when the sea water conforms to certain meteorological conditions can it constitute sea salt resources. In China, only the coastal areas where the annual evaporation is more than 1600 mm and the precipitation is less than 800mm are suitable for drying salt and have the manufacturing value of economic scale.

In China, the areas with the above conditions are mostly concentrated in the north, and the salt farms are mainly distributed along the Bohai Sea and the Yellow Sea. However, with the developed economy and shortage of land resources in the coastal areas of our country, the area of salt fields and the output of sea salt are also reduced accordingly.

Dapu Yantian, Lianyungang City

In the beginning, people used to scrape salty soil impregnated with sea water for a long time, pour bittern, and fry salt in a pan. In modern times, the sun method is commonly used to produce sea salt, that is, sea water is introduced into the salt field at high tide, and the sea water is evaporated and condensed into salt by using the sun and wind.

The method of solarization can make full use of natural energy, but it must be carried out in the season of sufficient sunshine and dry air, and the climate should have a more obvious and longer dry season, as well as high concentration of sea water, broad and flat shoals and so on.

Not all the sea water is suitable for salting in the sun.

The production method of lake salt varies according to the resources. If it is a salt lake that has formed stone salt deposits and rich intercrystalline brine, stone salt can be mined directly, as can be done in most salt lakes in China. On the other hand, for those salt lakes that have not formed stone salt deposits or have little stone salt deposits, salt fields must be built by the lakeside, brine from the lake should be introduced and salted by the sun.

The preparation principle of lake salt is the same as that of sea salt, but the concentration of salt lake brine is higher and the area of evaporation pool is less than that of sea salt.

Salt formation of salt lake brine in the sun

According to the product form, well and mineral salt is divided into liquid salt and solid salt. According to the production process, solid salt is divided into vacuum salt production and brine beach drying. Well and mineral salt is the absolute main source of salt in our country.

Xizang Mangkang salt well ancient salt field uses the method of mineral brine beach to make salt.

Rock salt is an ancient ocean or salt lake, which is formed by the gradual evaporation of water and deposition for a long time, or coupled with some crustal changes. It is common in dried-up salt lakes or underground salt deposits. If the purity of rock salt is high enough, it can be sold after grinding and screening, and when it is not pure, it can be dissolved into salt water and then purified.

The history of rock salt production in China is only a few hundred years. In the 58 year of Emperor Qianlong of the Qing Dynasty (1793), inclined shaft mining was adopted in Yunnan area. There are large-scale stone salt deposits in Qinghai, Sichuan, Hubei, Jiangxi and Jiangsu, especially in the Qaidam Basin, which means "Yanze" in Mongolian.

Mining of Chaka Salt Lake Salt Mine

Generally speaking, lake salt is the kind of salt with the lowest production cost, energy consumption and pollution in China, but the producing area of lake salt is distributed in the inland of western China, and the transportation cost increases the salt price and limits the development of lake salt.

Salt mining in China has a long history. Salt production in China has a history of five or six thousand years. As early as the Neolithic Age, the technology of "boiling the sea into salt" was already available. Subsequently, the production of lake salt and well salt appeared one after another. In thousands of years, the economic development and social progress of the salt industry have become an important pillar of national finance.

In the ancient times of Shennong, Shashi first invented cooking the sea for salt.

It is respected as Yanzong by later generations, and now there are temples dedicated to Yanzong in many places.

Salt cooking technology has gone through two stages of development: pottery cooking salt and metal cooking salt.

Cooking salt in pottery was popular as early as the Spring and Autumn period. Hebei Haixing salt-making site is an important salt-making site in the Spring and Autumn period. A large number of black-gray plant ash, gray pottery utensils and hearth coke blocks were unearthed in the site, indicating that the production at that time has a considerable scale.

A helmet used to cook salt.

(figure: museum.sdu.edu.cn) ▼

Metal pot salt cooking began in the Han Dynasty, when the use of metal salt cooking workers with prison pots, plates of iron and so on. A large iron pan used to boil salt, and iron is a tool for frying salt.

In the 20th year of Emperor Kangxi of the Qing Dynasty (1682), pan iron was no longer used and was replaced by an iron pot. With the improvement of salt production technology, sun salt has gradually replaced boiling salt production.

To this day, this traditional method of making salt is still preserved in some places.

Sea salt basking is mainly divided into inkstone sun, board sun, beach sun. Yantian Village in Hainan is the birthplace of inkstone salting, with a history of 1200 years.

The board sun, represented by Zhejiang, has been used since the reign of Jiaqing in the Qing Dynasty. The sun board is made of Cunninghamia lanceolata, which is about two meters long and 1 meter wide. When drying, the brine is injected into the salt plate, which can be made into salt on the same day in the peak season. Each salt plate can produce 2.5 kilograms of salt per day.

Not only is there a board in China.

Other countries in the world have similar methods of making salt.

Beach salt drying is a major technological breakthrough in the history of our country, which has the advantages of low cost and high output.

The origin of beach salting is that there are some low-lying depressions in coastal areas. When the typhoon comes, the sea water is washed into these depressions by the sea, and the tide recedes, and these depressions still accumulate sea water, and after the sun, they gradually form crystals. So later, coastal salt people slowly dug out low-lying depressions like this on the beach to hoard sea water and expose crystalline salt.

The traditional salt drying process in Yangpu, Hainan is to inject filtered sea water into the stone trough.

Or when the sea water is at high tide, the sea water overflows into these grooves and the hot sun is exposed to salt.

The production of well and mineral salt has a history of more than two thousand years. The so-called well and mineral salt is extracted from the buried brine by drilling and evaporated and crystallized.

Sichuan is the main producing area of well and mineral salt in China, and Zigong is known as the "salt capital". It is said that during the construction of Dujiangyan, Li Bing found brine underground and dug Guangdu Salt well, the first salt well in China, which opened the prelude to well salt production in China.

From the bricks in the portrait, we can vaguely see the splendor of salt making in Sichuan in ancient times, ▼.

In Zigong, towering cranes are all over the city. A salt well has a crane, the most brilliant time reached more than 13000, the highest can reach 113m, it was the highest wooden structure in the world at that time.

During the Northern Song Dynasty, a "Zhuo tube well" appeared in Sichuan, the wellhead was as big as a bowl, the well was as straight as a tube, tens of feet deep, and the deep drilling technology was among the best in the world.

Such a narrow and deep well was drilled by hand at that time.

If you accidentally drill a leaky well, the well can only be scrapped by ▼.

Mangkang is a representative well salt production area of Xizang, which is located in the Hengduan Mountains in the southeast of Xizang Autonomous region. It has a unique primitive ancient salt-making technology in the world.

The salt field of Mangkang Salt well is built on the steep hillside of the bank of the Lancang River. it is a platform supported by rows of wooden pillars, flattened with soil and fine sand, each of which is no more than seven or eight square meters. The brine dumped in the salt field is slowly evaporated by sunlight and can be crystallized into salt in a day or two. Today, this ancient method of making salt is still used here.

The salt field leaning on the mountain and water has the beauty of the integration of man and nature.

In the 20th century, the production technology of China's salt industry has made great progress. Sea salt generally realizes the mechanization and semi-mechanization of salt production. The well and mineral salt adopts electronic and micro-control technology. Lake salt production has also achieved mechanized mining and transportation.

China's largest salt producer is not a boast.

After the 21st century, China has established its status as the largest country in the world's salt industry.

With the rapid development of salt industry, the consumption of salt in China has changed from edible salt in the past to industrial salt now.

In 1950, edible salt accounted for 88.9% of China's total salt production, while industrial salt accounted for only 6.2%. Now, industrial salt accounts for nearly 90% of total consumption, and edible salt accounts for about 10%.

From changes in the use of salt

We can see the history of the rise of Chinese industry ▼

Among them, industrial salt is mostly made of sea salt and lake salt. The comprehensive utilization of seawater bittern in China is carried out around bromine and potassium, and the usual method is to produce potassium first, and then extract bromine by distillation. Magnesium chloride can be obtained by further evaporation and concentration of the old brine after potassium and bromine production.

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The salt lake resources developed earlier in China are Yuncheng Salt Lake in Shanxi Province, and its main products are mirabilite, alkali sulfide, sodium chloride, sodium silicate and bromine, among which the output of mirabilite accounts for more than 40% of the country.

Qinghai is another salt and chemical base in China. Chaerhan Salt Lake in Qaidam Basin is the largest known salt lake in China, with a storage of about 60 billion tons of chloride-based salt, of which 150 million tons of potassium salt is second only to the Dead Sea, ranking second in the world.

Don't worry, there will be no shortage of salt without anything.

Hengping-Chaerhan Salt Lake ▼

Qinghai salt chemical base mainly produces potassium chloride, magnesium chloride, carnallite, sodium sulfate, Yuanming powder, boric acid and borax.

Xizang is also rich in salt lake resources, with 170 large and small salt lakes, covering an area of 6000 square kilometers, which is one of the main salt lake distribution areas in the world.

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Although 87% of our edible salt is mine salt, some people still worry that the earth is a whole and the possibility of nuclear contamination cannot be ruled out.

In fact, the salt deposits in wells and mines in China are relatively deep, such as the salt deposits in Sichuan are all about 1000 meters, and those in Hunan, Hubei, Yunnan and other places are about 300 meters and 500 meters. Some salt mines are even buried at a depth of 2500 to 3000 meters, such as the salt mine in Nanchong, Sichuan.

If these deep-buried land bottom salt, nuclear radiation tests are excessive, then we living on the surface, I am afraid we will already be exposed to nuclear radiation.

Reference:

[1] Zhang Dean. Development and Prospect of Salt production Technology in China [J]. Salt and Chemical Industry, 2016, 45 (1): 7-14.

[2] Hu Ning Scientific development of China's salt industry [J]. China well and Mineral Salt, 2006, 37 (2): 7.

Fu Yuhang, Chen Yong, Zeng Yang. Discussion on the present situation and future development countermeasures of salt production [J]. China well and Mineral Salt, 2021.

Kong Zhiyuan, Lin Meiying. Production pattern and consumption status of salt industry in Asia-Pacific region [J]. China well and Mineral Salt, 2002, 33 (4): 4.

[5] Su Jiaqing. Vacuum salt production [M]. Beijing: China Light Industry Press, 1983.

Cao Ye, Qiu Guoyu, Zou Zhendong. General situation of China's salt resources and analysis of its industrial situation [J]. Inorganic Salt Industry, 2018, 50 (3): 5.

[7] Hou Wei. Study on the structure Adjustment of China's Salt Industry [D]. Beijing: University of International Business and Economics, 2005.

[8] Ren Haibo. Study on the selection of brine treatment methods in modern salt industry [D]. Zhengzhou: Zhengzhou University, 2003.

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