preparation method
(1) beach field method
The temperature changes in different seasons in nature are used to evaporate the water in the raw material liquid and crystallize the crude mirabilite. In summer, salt water containing sodium chloride, sodium sulfate, magnesium sulfate, magnesium chloride, etc. is poured into the beach field, and the crude mirabilite is precipitated in winter after sun evaporation. This method is the main method to extract mirabilite from natural resources. The process is simple, the energy consumption is low, but the operating conditions are poor, and impurities such as mud and sand are easily mixed in the product.
(2) Mechanical freezing method
The raw material liquid is heated and evaporated by mechanical equipment and then frozen to-5 ~-10℃ to precipitate mirabilite. Compared with 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 of salt lakes.
Mainly used for sulfate-carbonate salt water containing various components. While extracting various useful components, the crude mirabilite 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, so that sodium carbonate can be converted into sodium bicarbonate and crystallized; Cooling the mother liquor to 5-15 DEG C to crystallize borax; The secondary mother liquor after borax separation is frozen to 0 ~ 5℃ to separate out mirabilite.
(4) Other methods.
Can be prepared by the reaction of sulfuric acid and sodium hydroxide. H2SO4+ 2NaOH→Na2SO4+ 2H2O。 It can also be prepared by extracting natural products.
It can also be prepared by the reaction of sodium bicarbonate and sulfuric acid: 2nacho3+H2SO4 → Na2SO4+2h2o+2co2.
Sodium sulfate can be prepared by heating sodium chloride solid and concentrated sulfuric acid in laboratory. 2NaCl+H2SO4→2HCl↑+Na2SO4
Or by reacting sodium hydroxide with copper sulfate: 2NaOH+CuSO4 = = = = Na2SO4+Cu (OH) 2↓
At home, sodium carbonate or sodium bicarbonate can be reacted with copper sulfate to obtain:
2CuSO4+2Na2CO3+H2O=Cu2(OH)2CO3↓+2Na2SO4+CO2↑
4NaHCO3+2CuSO4=Cu2(OH)2CO3↓+2Na2SO4+3CO2↑+H2O
Beach field method, mechanical freezing method and salt lake comprehensive method can be used. Beach method and mechanical freezing method are suitable for processing seawater brine with Na, Mg, Cl and SO42- as main components and other mirabilite ores. 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 water-salt system.
4 Main uses
(1) Chemical industry is used to manufacture sodium sulfide, sodium silicate, water glass and other chemical products.
(2) Cooking agent used in papermaking industry to make sulfate pulp.
(3) Glass industry is used as cosolvent instead of soda ash.
(4) Textile industry is used for blending spinning coagulants of vinylon.
(5) Used in nonferrous metallurgy, leather, etc.
(6) It is used to make sodium sulfide, paper pulp, glass, water glass and enamel, and also used as laxative and antidote for barium salt poisoning. It is a by-product when hydrochloric acid is made from salt and sulfuric acid. Used in chemical industry to make sodium sulfide, sodium silicate, etc. Used in laboratory to wash off barium salt. It is used as raw material for preparing NaOH and H₂SO₄ in industry, and also used in papermaking, glass, printing and dyeing, synthetic fiber, leather making, etc. Sodium sulfate is the most commonly used post-treatment desiccant in organic synthesis laboratory.
(7) Mainly used as filler for synthetic detergent. Cooking agent used in papermaking industry to make sulfate pulp. Glass industry is used to replace soda ash. Chemical industry is used as raw material for manufacturing sodium sulfide, sodium silicate and other chemical products. Textile industry is used to prepare vinylon spinning coagulation bath. Medicine is used as laxative in industry. It is also used in nonferrous metallurgy, leather, etc.
(8) Calcium sulphoaluminate, a hydration product, is generated more quickly, thus accelerating the hydration and hardening speed of cement. The dosage of sodium sulfate is generally 0.5% ~ 2% of the cement quality, which can improve the early strength of concrete by 50% ~ 100%. The 28-day strength sometimes increases, sometimes decreases, and the increase rate is about 10%, depending on the cement variety, curing conditions and its dosage. It is also used as a filler of synthetic detergent, and also used in paper industry, glass industry, chemical industry, textile industry and pharmaceutical industry.
(9) Used as analytical reagent, such as dehydrating agent, digestion catalyst during nitrogen determination, and interference inhibitor in atomic absorption spectrometry. It is also used in the pharmaceutical industry.
(10) It is used in chemical industry, paper making, glass, dyestuff, printing and dyeing and pharmaceutical industries. It is also used in the manufacture of synthetic fiber, leather making, nonferrous metallurgy, enamel, etc. It is also used as an additive in detergents and soaps.
(11) It can be used as a buffer in sulfate zinc plating to stabilize the ph value of the plating solution.