In industry, salt is dried with seawater, or boiled with well water or salt lake water to precipitate salt crystals. The salt made in this way has many impurities and is called raw salt. Crude salt can be dissolved, precipitated, filtered and evaporated to produce refined salt.

Modern salt is made by "vacuum salt making" technology. Pure brine is injected into the evaporation tank, and high-temperature steam heats the brine through heat exchange, so that the water in the brine evaporates and the salt crystallizes.

Scientists also use the principle of lowering the boiling point of liquid under the condition of low air pressure to reduce the heat energy consumption and make the salt crystallize out as soon as possible by reducing the air pressure in the evaporation tank. This is the "vacuum salt making" technology. ?

Salt has a wide range of functions: sterilization, tooth protection, beauty, skin cleaning, decontamination, medical treatment and important chemical raw materials.

Chemical properties:

1, which can react with silver nitrate to obtain silver chloride precipitate;

2. The solid salt can be heated with concentrated sulfuric acid to obtain hydrogen chloride gas;

3. Chlorine, hydrogen and sodium hydroxide can be obtained by electrolysis of sodium chloride solution;

4. Sodium and chlorine can be obtained by electrolytic melting of sodium chloride.

Refer to the above? Baidu encyclopedia-salt