Evaporation is the oldest way for human beings to obtain salt crystals, which refers to the way of evaporating into salt by using solar radiation heat, and can be applied to sea salt, lake salt and pond salt. Also known as cooking, it is a method of concentrating brine by fire evaporation to make salt. Its forms include the earliest stone pot type, flat pot type, steam utilization type, vacuum type and today's pressurized vacuum type.
The extraction method is to introduce seawater into the salt on the beach, gradually evaporate water through sunlight and wind, and slowly concentrate to crystallize the salt. After extracting potassium chloride from brine, the remaining brine contains potassium chloride, magnesium chloride and a small amount of sodium chloride. These three substances can be separated by their solubility differences. The solubility analysis of the three substances shows that the solubility of magnesium chloride (54.3 g) is greater than that of potassium chloride and sodium chloride at room temperature (20℃).
The origin of salt:
In ancient times, there were three natural salt springs in eastern Chongqing and western Hubei-Baoyuan Mountain Salt Spring in Wuxi, Funiu Mountain Salt Spring in Yushan Town of Pengshui and Qingjiang Salt Spring in Changyang County of Hubei Province. Baoyuan Mountain is the earliest known salt spring in China, which has a history of 5,000 years and is still flowing today. In ancient times, before the invention of deep well brine extraction technology, the natural salt spring of the Three Gorges was the earliest source of salt supply in inland areas. The Pakistanis control this precious resource. Wuxi Baoyuan Mountain Salt Spring is a poor place with a vast territory and a sparse population.
This is the earliest Fuku in ancient China. The whole saltworks is five miles long, and people come and go on the field, and all rivers contend for currents, forming the spectacle of "thousand stoves and smoke". The whole Hanzhong basin, the two lakes basin, the Sichuan basin and the western Hubei region should be supplied by Daning saltworks. Ningchang Town was a big city in ancient times. At its peak, it became a small town with a population of 14000, where business travelers from all directions gathered. About 654.38 million people make a living from salt industry. Daning Salt Field is surrounded by mountains, and the locals say that apes are also difficult to climb.