Is coarse salt used for cooking?

　　Coarse salt Also known as solar salt, it is unrefined large-grain salt typically used for pickling vegetables. In rural areas, it's also used to mix feed for livestock. While coarse salt is not recommended in food, it is still consumed in very poor mountain villages due to its affordability. Here is the process of making coarse salt:

Solar salt can be extracted from seawater. The method involves introducing seawater into salt pans on the beach.

Sunlight and wind gradually evaporate the water to allow it to evaporate, slowly concentrating the solution until salt crystals form. From brine, potassium chloride is extracted after solar salting. The remaining brine contains potassium chloride, magnesium chloride,

and a small amount of sodium chloride.

These three substances can be separated based on their different solubilities. Analysis of the solubility of these substances shows that at room temperature (20℃), magnesium chloride has a higher solubility (54.3 grams) than potassium chloride and sodium chloride. Therefore, at room temperature, adding an appropriate amount of water to the mixture will dissolve most of the magnesium chloride,

allowing it to be separated and removed.

Then, based on the characteristic that below 27℃, the solubility of potassium chloride is lower than that of sodium chloride, adding an appropriate amount of water to the remaining mixture can cause sodium chloride to dissolve in water,

resulting in crude potassium chloride. Further crystallization and recrystallization of the crude potassium chloride

can produce refined potassium chloride.

Sodium dissolves in water, yielding crude potassium chloride. Further crystallization and recrystallization of the crude potassium chloride,

can result in refined potassium chloride.