1. Beach field method

The water in the raw material liquid is evaporated by using the temperature changes in different seasons in nature, and the crude thenardite is crystallized. In summer, salt water containing sodium chloride, sodium sulfate, magnesium sulfate, magnesium chloride and other ingredients is poured into the beach field, evaporated by the sun, and then precipitation of mirabilite in winter. This method is the main method for extracting mirabilite from natural resources. The process is simple and the energy consumption is low, but the operating conditions are poor, and impurities such as mud and sand are easily mixed into the product.

2. Mechanical freezing method

Glauber's salt is precipitated when the raw material liquid is heated and evaporated by mechanical equipment and then frozen to -5～-10℃. Compared with the beach field method, this method is not affected by seasons and natural conditions. The product quality is good, but the energy consumption is high.

3. Comprehensive utilization method of salt lake

Mainly used for sulfate-carbonate salt water containing various components. While extracting various useful components, the crude Glauber's salt is separated. For example, when processing salt lake water containing sodium carbonate, sodium sulfate, sodium chloride, boride, potassium, bromine, and lithium, the salt lake brine can be carbonized first to convert sodium carbonate into sodium bicarbonate to crystallize; cool the mother liquor to 5-15°C, The borax is crystallized; the secondary mother liquor after the borax is separated is frozen to 0-5°C, and then mirabilite is precipitated. [1]

4. Other methods

It can be obtained by the reaction of sulfuric acid and sodium hydroxide. H2SO4+ 2NaOH→Na2SO4+ 2H2O. Extraction from natural products can also be obtained.

It can also be prepared by reacting sodium bicarbonate and sulfuric acid: 2NaHCO3+H2SO4→Na2SO4+2H2O+2CO2↑.

In the laboratory, sodium chloride solid and concentrated sulfuric acid can be used to prepare sodium sulfate under heating conditions. 2NaCl+H2SO4(concentrated)→2HCl↑+Na2SO4

Or prepared by reacting sodium hydroxide and copper sulfate: 2NaOH+CuSO4=Na2SO4+Cu(OH)2↓

It can be prepared by reacting sodium carbonate or sodium bicarbonate with copper sulfate in the family:

2CuSO4+2Na2CO3+H2O=Cu2(OH)2CO3 ↓+ 2Na2SO4 +CO2↑

4NaHCO3+2CuSO4=Cu2(OH)2CO3↓+2Na2SO4+3CO2↑+H2O

The beach field method, mechanical freezing method, and salt lake comprehensive method can be used. The beach field method and the mechanical freezing method are suitable for processing seawater type brine and other various Glauber's salt mines with Na, Mg, Cl, SO42- as the main components. Because the solubility of sodium sulfate decreases sharply at low temperature, crude mirabilite can be separated from brine according to the phase equilibrium relationship of the water-salt system.