Cryolite is an important raw material used in the production of chemicals, and its chemical formula is Na3AlF6. Cryolite is mainly used in the smelting of aluminum, and as a flux in the electrolytic refining of aluminum, it can lower the melting point of alumina and improve the electrical conductivity of the electrolyte. The following is about the manufacturing method of cryolite:
1. Hydrofluoric acid method
Hydrofluoric acid method is the main method to produce cryolite, and its process includes the steps of batching, reacting, evaporating, cooling, crystallizing, centrifugal separating and drying. The specific steps are as follows:
(1) Ingredients: Aluminum hydroxide, soda ash and sodium fluoride are ingredients according to a certain proportion and added into the reactor.
(2) Reaction: Add a certain amount of water in the reactor, heat to a certain temperature, so that the ingredients are fully reacted to produce cryolite and sodium hydroxide.
(3) Evaporation: pour the reaction solution into the evaporation tank, heat and evaporate to concentrate the solution.
(4) Cooling: Cool the concentrated solution to a certain temperature to precipitate cryolite crystals.
(5) Crystallization: Crystallization is carried out through crystallizer to get cryolite crystals.
(6) Centrifugal separation: the mother liquor and crystals after crystallization are centrifugally separated to obtain pure crystals of cryolite.
(7) Drying: the crystals are dried to obtain the final crystals product.
2. Acid method
Acid method is also a commonly used method to produce cryolite, and its process includes the steps of batching, acid digestion, neutralization, evaporation, crystallization, centrifugal separation and drying. The specific steps are as follows:
(1) Ingredients: Ingredient sodium fluorosilicate and sulfuric acid in a certain proportion and add them into the reactor.
(2) Acid digestion: Heat to a certain temperature in the reaction kettle, so that sodium fluorosilicate reacts with sulfuric acid to generate hydrogen fluoride and sodium sulfate.
(3) Neutralization: Pour the reaction liquid into the neutralization tank, add soda ash for neutralization reaction to generate cryolite and sodium sulfate.
(4) Evaporation: Pour the neutralized solution into the evaporation tank, heat and evaporate to concentrate the solution.
(5) Crystallization: Cool the concentrated solution to a certain temperature and precipitate cryolite crystals.
(6) Centrifugal separation: centrifugal separation of the mother liquor and crystals after crystallization to obtain pure crystals of cryolite.
(7) Drying: Dry the crystals to get the final cryolite product.
The above are two common methods of manufacturing cryolite, but the specific production process may vary depending on different manufacturers and equipment. During the production process, safety needs to be paid attention to avoid the leakage of toxic and harmful gases such as hydrogen fluoride, and at the same time, the quality and purity of the products should be ensured to meet the requirements of chemical production.
