In China, the origin of salt was as far back as 5,000 years ago during the Yanhuang period. Su Shi, the inventor, was the originator of making salt from seawater and cooking it with fire, and was later honored as a salt Sect. Salt is a ubiquitous substance in the crust. Because it is soluble in water, it is often brought into rivers by rain and then flows into the sea. According to statistics, about 1.65438+ tons of salt flows into the ocean from land every year, and the global ocean salt content is about 450 billion tons. According to natural conditions, salt can be divided into four types: sea salt, lake salt, well salt and mineral salt.
The earliest salt mining method used by humans was scraping salt crystals from dry river beds or lake beds with high salt content, but it didn't take long for people to invent more complicated salt making methods. The first commonly used salt is sea salt. Sea salt is mainly obtained by developing salt fields on the seashore with suitable climate and geological conditions, relying on sun exposure and natural evaporation to precipitate salt. Sea salt is produced in the seashores of many parts of the world, such as China in Oceania, South Korea, India, Australia and the Mediterranean coast in Europe.
Method for producing salt
1, the production of sea salt generally uses the sun drying method, also known as the beach sun drying method, that is, the coastal beaches are used to build dams to open up salt fields, and seawater is pumped by tides to attract seawater to fill ponds and evaporate into brine through sunlight. When the concentration of brine evaporates to 25 degrees Pompeii, sodium chloride precipitates out, which is the original salt.
2. The production of mine salt is mainly divided into two steps: bittern extraction and salt making. Different types of mines adopt different brine extraction methods. The methods of extracting natural brine include extraction, gas lift, brine extraction, deep well submerged brine pump and self-injection brine extraction.
3. Lake salt is primary salt and regenerated salt, which mainly depends on mining or beach drying. In terms of mining, some lakes have been evaporated for a long time, and sodium chloride is deposited at the bottom of the lake, so it can be directly fished without processing.