At the end of the Warring States period, Sichuan began to dig wells, take brine and fry salt. Qi Guanzhong implements the policy of "official mountain and sea", that is, salt is made by the government and all products are transported and sold by the government.
From the Han Dynasty to the Ming Dynasty, beaches, salt wells and salt lakes were opened all over the country, except for three years when Emperor Wen of Sui Dynasty opened the emperor and ten years when Emperor Xuanzong of Tang Dynasty opened the first century. 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.
During the reign of Qianlong and Jiaqing in Qing Dynasty, Zigong salt industry had entered the stage of capitalist workshop handicraft industry. 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.
/kloc-After the middle of the 0/9th century, some countries with more developed technologies have successively used mechanical equipment to dig wells, extract brine and make salt, absorb moisture, make brine, crystallize, collect and transport salt, and mine lake salt and mineral salt, and the production scale is expanding day by day.
19 12 used steam locomotive to pump brine in Tianjin Hangu saltworks, 1925 used diesel engine to pump water. Other sea salt areas have gradually begun to use machinery, but the development is slow.
Extended data:
Raw materials for salt-making industry
1, 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 3800m·m m. It has been found that seawater contains more than 80 chemical elements, forming 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.
2. 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.
3. 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. There are generally solid and liquid phases, but there are also brine lakes and dry salt lakes.
4. 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.
Baidu encyclopedia-salt making