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.