1. Nada Method
The temperature changes in different seasons in nature are used to evaporate the water in the raw material liquid to crystallize the crude Glauber's salt. In summer, salt water containing sodium chloride, sodium sulfate, magnesium sulfate, magnesium chloride and other ingredients is poured into beach fields, and evaporated by the sun, and coarse Glauber's salt is precipitated in winter. This method is the main method to propose Glauber's salt from natural resources. The process is simple, the energy consumption is low, but the operating conditions are poor, and the product is easy to be mixed with impurities such as mud and sand.
2. Mechanical freezing method
Glauber's salt is precipitated when the raw material liquid is heated and evaporated by mechanical equipment and frozen to -5～-10℃. Compared with the Tanada 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 of Salt Lake
Mainly used for sulfate-carbonate salt water containing multiple 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 out; cool the mother liquor to 5-15℃, The borax is crystallized out; the secondary mother liquor after the separation of borax is frozen to 0～5℃, and thenardite is precipitated. [1]
4. Other methods
Can be prepared by the reaction of sulfuric acid and sodium hydroxide. H2SO4+ 2NaOH→Na2SO4+ 2H2O. Extracted from natural products can also be obtained.
It can also be prepared by the reaction of 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. 2NaCl+H2SO4(concentrated)→2HCl↑+Na2SO4
Or it can be 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 household:
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 mechanical freezing method are suitable for processing seawater type brine with Na, Mg, Cl, and SO42- as the main components, and various other Glauber's salt ore. Because the solubility of sodium sulfate decreases sharply at low temperatures, crude Glauber's salt can be separated from brine according to the phase equilibrium relationship of the water-salt system.
