Development course and main characteristics of salt making

In history, there was an act of cooking salt in a pot.

In the late Qing Dynasty, salt people in zhang wan, Ningde, Qingshan, Chengnan and other places tried the technology of drying brine to make salt.

In the 20th year of the Republic of China, Ye Liyi and others from Fuding built a garden in Du Wen, Qinyu to make salt. First of all, they use wooden boards to dry salt, which is small in quantity but low in quality. Later, they invited a Zhejiang master to teach them salt-making skills, which made the beach full of ridges and raised brine and dried salt.

In 1950s, Ningde and Fuding salt areas reformed salt-making technology, built tidal projects and enriched brine sources.

In the early 1960s, Sandu Salt Field in Ningde adopted the process of changing salt from dilute drying to diligent drying, and brine extraction was closely connected with the next brine crystallization process to improve the salt yield and quality.

Enlarging crystallization pool and brine evaporation pool to increase crude salt output.

At the end of 1970s, the open pit brine well was changed into a covered brine well.

Zhuo Xuesheng successfully developed DC electric axial flow pump, which solved the operation method of extracting brine from traditional treadmill.

By the end of 1980s, salt production in eastern Fujian was basically mechanized.

[ 1]

2 development editor

According to the data analysis of "20 13-20 17 China Salt Industry Demand and Investment Forecast and Analysis Report" [2], during the Eleventh Five-Year Plan period, China's salt industry developed rapidly, with an average annual increase of 12.26% and a substantial improvement in its quality.

At present, the characteristics of salt market in China are obvious, and the reform of franchise system is in a swing stage, which has affected the development of the industry to some extent.

Statistics show that from 2006 to 20 10, the growth rate of salt sales revenue was 19.95%, 4.47%, 24. 15%, 4.09% and 27.30% respectively, and the growth rate fluctuated greatly. At the same time, the growth rate of total profit also fluctuates.

After 60 years of development, adjustment is the inevitable choice at present.

Innovating the reform mode of salt industry and bringing new vitality to salt industry enterprises is the primary task of salt industry enterprises.

Merger, integration and reorganization within the industry, elimination of backward productive forces, joint production and marketing, cross-regional and cross-industry joint reorganization and optimization of industrial layout are the future development directions of China's salt industry.

At present, for their own development, many salt-making enterprises are taking actions of merger, reorganization and diversification, uniting the downstream, extending the industry, developing circular economy and enhancing the comprehensive competitiveness of the industry.

3 Production Category Editor

Raw salt production, salt processing and comprehensive utilization of brine resources.

The production scope includes: taking seawater, salt lake brine or underground brine, and solarizing in the salt field to form salt; The brine obtained by drilling underground natural brine or injecting water to dissolve underground rock salt is heated and boiled in a round tank or a flat tank or concentrated into salt by vacuum hot-pressing evaporation; Underground rock salt is mined by water-soluble drilling, and the produced brine is directly used as raw material for alkali production; Mining underground rock salt and natural crystalline rock salt directly in salt lake; Processing raw salt according to the purpose; Extracting other chemical products from salt-making mother liquor.

Salt industry is both a mining industry and a processing industry.

Salt production is often concentrated in some areas and sold all over the country.

Salt is one of the oldest commodities.

4 historical evolution editor

The salt-making industry has a long history, and its development has gone through the process from primitive manual production and manual mechanical production to mechanized and modern production (see the history of salt-making technology).

Humans first collect the brine and salt existing in nature, including the natural brine and rock salt on the surface and the salt naturally crystallized in coastal depressions for food.

More than 5,000 years ago, China began scraping coastal saline soil, drenching it with brine and frying salt.

In areas with natural brine, the production method of "burning charcoal first, splashing with salt well water and scraping salt" is adopted.

At the end of the Warring States period, Sichuan began to dig wells, take brine and fry salt.

Qi Guanzhong (BC? ~ 645 years ago, the policy of "official mountain and sea" was implemented, that is, salt was produced by the government and all products were transported and sold by the government.

However, from the Han Dynasty to the Ming Dynasty, beaches, salt wells and salt lakes all over the country were open to the people for free production and sales except for the period from the third year of Wendi (583) to the tenth year of Xuanzong of Tang Dynasty (722). In other dynasties, in order to increase fiscal revenue, most of them implemented monopoly system, controlled the production and sales of salt with severe punishment, and forced salt farmers to produce salt by forming corvee.

Although the salt production in Shanxi Lake in Sui and Tang Dynasties formed a new process of "ploughing and watering and drying", salt production in Fujian Province in Song and Yuan Dynasties also partially adopted the drying method, but the production scale was small, the tools and equipment were rudimentary, and there was only simple cooperation among producers, which still remained in a small production state of one household.

Well salt is a different story.

In the Song Dynasty, Zhuotong well appeared in Sichuan, and it was the first time to drill a well with a drill ("cutting edge" file).

From the Ming Dynasty to the Qing Dynasty, hand tools were gradually improved, division of labor and cooperation were clear, and commercial capital was increasingly transformed into industrial capital.

With the influx of migrants, the labor market has gradually formed. By the years of Qianlong (1736 ~ 1795) and Jiaqing (1796 ~ 1820) in Qing Dynasty, Zigong salt industry had entered the stage of handicraft industry in capitalist workshops.

After 1835, black brine wells, rock salt wells and deep natural gas wells were dug one after another, which provided rich raw materials and energy for salt industry.

The natural leaching of rock salt wells leads to karst caves, water injection in one well and brine extraction in many wells, which promotes the combination of related wells and greatly promotes the development of handicrafts in salt areas.

Under the influence of the industrial revolution, after the middle of the19th century, some countries with more developed technologies have successively adopted mechanical equipment to dig wells, collect brine, make salt, absorb moisture, make brine, crystallize, collect salt, transport salt, and mine lake salt and mineral salt, and the production scale is expanding day by day.

China Zigong Salt Area 19 12 uses steam locomotives to pump brine, Tianjin Hangu Salt Field 1925 uses diesel engines to pump water, and other sea salt areas gradually adopt machinery, but the development is slow.

From 19 10 to 1949, the annual salt production in China increased from1780,000 tons to 2.98 million tons, with an average annual growth rate of only 1.3%.

After 1949, China's salt-making industry developed rapidly and gradually realized mechanized and modern large-scale production.

5 salt raw material editor

The total proven salt resources in the world are about 6.4×10.07 billion tons.

Among them, the salt content of seawater (including seabed sediments) is 43×10.7 billion tons, rock salt is 2/kloc-0 /×/kloc-0.7 billion tons, and natural brine in salt lakes and underground is 3/kloc-0.0 billion tons.

New rock salt deposits are still being discovered.

seawater

The ocean area accounts for 70.8% of the total surface area of the earth, and the average depth of the ocean is about 3800 meters.

It is found that seawater contains

More than 80 chemical elements form a variety of dissolved salts, with a total salt content of about 3.5%.

The content of sodium chloride is about 2.7%, which is an important raw material for salt making.

rock salt

Solid deposits of sodium chloride in the earth's crust.

It is formed by gradual evaporation, concentration and deposition of salt-rich water in a closed and semi-closed sedimentary basin under favorable geological structure and arid climate conditions.

Its salt substances come from the mainland, and the sedimentary conditions are pure inland basins, which are continental deposits. The ore body is thin and often coexists with mirabilite, glauberite, gypsum and anhydrite. Salt substances come from the ocean, and the sedimentary conditions are closely related to the ocean. The ore body is thick in single layer and contains many components such as potassium, magnesium, bromine and iodine. Salt substances come from land and sea, and the sediments with sedimentary conditions between land and sea are marine sediments.

Under the strong tectonic force and gravity, rock salt ore bodies are prone to plastic deformation and uplift, forming salt domes, which are almost composed of pure salt and are excellent rock salt deposits.

The reserves of rock salt in the world are the largest in the United States, accounting for about 30% of the world total; The Soviet Union, Canada and the Federal Republic of Germany account for about 55% ~ 60%.

China's rock salt resources are mainly distributed in Sichuan, Yunnan, Hunan, Hubei, Anhui, Jiangsu, Henan, Guangdong, Qinghai, Xinjiang, * * and other places.

salt lake

The rock salt and brine deposits formed since Quaternary are distributed in the arid inland closed-flow areas of the world, which are divided into two salt lakes in the northern and southern hemispheres and the equatorial salt lake belt, with the northern hemisphere salt lake belt as the main one.

Generally, solid phase and liquid phase coexist, and there are also brine lakes and dry salt lakes.

Among more than 30 countries with lake salt resources, China ranks first, accounting for more than half of the world's total, and Qaidam Basin in Qinghai is known as "the world of salt". Followed by the Soviet Union, the United States, and Australia, Ethiopia, Libya, Morocco and other countries.

Underground natural brine

When sedimentary rocks are formed, seawater sealed in crevices and cracks of minerals or rocks, brine condensed when underground salt mud is cooled, or brine formed by underground leaching of salt minerals.

Distributed in more than 20 countries in the world, especially the United States, China, Malaysian, Israeli, Ethiopian, Soviet Union and other countries.

In addition to salts such as sodium chloride, there are substances such as bromine, iodine, boron, potassium, strontium, lithium and rubidium, which have high economic value.

6 China Salt Industry Editor

Since 1950s, China's salt industry has undergone obvious changes, and its output has increased rapidly (table 1), ranking third in the world, only lower than that of the United States and the Soviet Union.

1952 annual salt production

4.94 million tons, exceeding the highest annual output in history (1.943+39 1.8 million tons of salt).

After 1979, salt industry introduced advanced technology, further developed production, and paid attention to quality improvement and variety development.

1989 produced 28.27 million tons of salt, the highest level in history; During the 40 years from 1950 to 1989, the salt production increased by 1 1.47 times, with an average annual increase of more than 6.2%.

1989 There are 27 large and medium-sized saltworks, accounting for about 60% of the national output.

Great progress has been made in salt making technology.

The production process of sea salt was improved, and a new process of covering the crystallization tank with plastic film was adopted.

In many salt fields, the main operating procedures such as salt collection, transportation and accumulation have been mechanized. Rotary drilling rig and large turbine drilling rig are widely used in drilling; Gas lift method and submerged brine pump are used to extract underground natural brine; In rock salt mining, various borehole water-soluble mining methods and chamber water-soluble mining methods have been popularized. Salt production adopts vacuum evaporation, centrifugal dehydration, fluidized bed drying, belt conveyor transportation and mechanical packaging. The main salt fields in the lake salt area are transported by large-scale combined salt mining machine (ship) and hydraulic pipeline.

The National Development and Reform Commission recently approved the vacuum salt production project of Jiangxi Dafu Co., Ltd. with an annual output of 500,000 tons.

The total investment of the project is 263.66 million yuan, and the construction scale is 500,000 tons of refined salt and 35,000 tons of anhydrous nitrate per year.

This is the first salt-making project approved by the National Development and Reform Commission since the reform of the national investment system and the implementation of the approval system in the salt-making industry.

[3]

During the "Eleventh Five-Year Plan" period, China's salt industry developed rapidly, and the crude salt output increased by about 12.26% annually, and the quality was greatly improved.

At present, the characteristics of salt market in China are obvious, and the reform of franchise system is in a swing stage, which has affected the development of the industry to some extent.

Statistics show that from 2006 to 20 10, the growth rate of salt sales revenue was 19.95%, 4.47%, 24. 15%, 4.09% and 27.30% respectively, and the growth rate fluctuated greatly. At the same time, the growth rate of total profit also fluctuates.

After 60 years of development, adjustment is the inevitable choice at present.

Innovating the reform mode of salt industry and bringing new vitality to salt industry enterprises is the primary task of salt industry enterprises.

Merger, integration and reorganization within the industry, elimination of backward productive forces, joint production and marketing, cross-regional and cross-industry joint reorganization and optimization of industrial layout are the future development directions of China's salt industry.

At present, for their own development, many salt-making enterprises are taking actions of merger, reorganization and diversification, uniting the downstream, extending the industry, developing circular economy and enhancing the comprehensive competitiveness of the industry.

7 World Salt Industry Editor

With the continuous growth of social demand, the world salt production has more than tripled in about 30 years since the 1950s.

In addition to China, there are 18 countries whose annual salt production exceeds 1 10,000 tons (Table 2).

In 654.38+0985, the total import and export volume of the world salt industry was 42.5 million tons, of which the import volume was 6.5438+0776 million tons, and the country with the largest import volume was 6.83 million tons in Japan. The export volume is 24.74 million tons, and the country with the largest export volume is Australia, which is about 4.95 million tons.

There are also some countries, such as the United States, the Soviet Union and Britain, which both export and import.

The United States has the largest import and export volume, with 1985 importing 5.63 million tons and exporting 820,000 tons.

Nowadays, salt-making enterprises in the world are gradually becoming large-scale. For example, in the Soviet Union, from 1955 to 1975, the output of large and medium-sized salt plants increased by 1.6 times, while small plants were gradually closed or merged. Salt-making enterprises in Europe and America have set up companies one after another, operating in a unified way from scientific research and design to production and sales.

The salt production of American 12 companies accounts for 88% of the national output (1974).

British Imperial Chemical Company almost monopolized the national salt industry.

Salt-making equipment is getting bigger and bigger and more automatic.

In 1950s, the vacuum evaporation salt-making equipment was mostly three-effect or four-effect, but it developed into five-effect or six-effect after 1960s.

In areas with sufficient electricity and low electricity prices, hot-pressing evaporation is also used.

For example, the hot-pressing evaporation salt-making equipment established in Italy by the French company Whiting Fermon has a production capacity of 6.5438+0.5 million tons/year, and the production operation is highly automated.

trend

In addition to large-scale enterprises and equipment automation, salt industry is also developing towards comprehensive utilization and diversified production.

Based on salt, it involves a wide range of chemical industries. For example, American channelization company and Dutch Akesu Salt Chemical Company both produce salt, caustic soda, soda ash, plastics and a variety of related chemical products, forming a comprehensive multinational group company.

The direct use of brine in alkali industry can save the crystallization process in salt plant and the molten salt process in alkali plant, improve production efficiency and be beneficial to mechanized production. For example, the amount of brine directly used in the United States has accounted for more than 48% (65,438+0,985) of the total salt production.

In addition, some countries with conditions also combine salt making with seawater desalination, and use brine obtained from seawater desalination to make salt.

If seawater is refined, 654.38+000 billion people can eat salt for 50 years.