Method for simultaneously producing sodium aluminofluoride and silica white

Abstract

The invention relates to a method for producing cryolite co-production of white carbon black, which comprises the following steps: (1) adding ice mother and ammonia water to water to prepare dilute ammonia water, reacting fluosilicic acid solution with dilute ammonia water to prepare white carbon black Carbon black seed crystals, the pH value of the white carbon black seed crystals is controlled between 6-8, and the reaction temperature is 30-40°C; (2) Add a certain amount of white carbon black seed crystals to the ammonolysis tank, wherein the crystals The amount of seed added can be adjusted as needed, and an appropriate amount of ice mother is added. Under the condition of the presence of seed crystals, sodium fluorosilicate and ammonia water are subjected to ammonolysis reaction at a temperature of about 60 ° C, and the pH value at the end of the reaction is greater than 8.0 , the white carbon black slurry that ammonolysis reaction generates is filtered, washed to obtain white carbon black ointment, wherein filtrate is ammonium fluoride, sodium fluoride mixed solution, and white carbon black ointment is dried to obtain white carbon black finished product; (3) will The mixed solution of ammonium fluoride and sodium fluoride produced by the ammonolysis reaction reacts with the sodium aluminate solution at a temperature of 80-100°C to form a cryolite slurry, which is filtered and dried to obtain a finished product of cryolite.

Description

technical field [0001] The invention relates to a method for producing cryolite and co-producing white carbon black. Background technique [0002] The chemical name of cryolite is sodium fluoroaluminate, and the molecular formula is Na 3 AlF 6 , It is mainly used in industry as a flux for aluminum smelting, in the silicate industry as an opalescent agent for glass and enamel, and in agriculture as a pesticide. The main raw material used in the aluminum smelting industry in the world is cryolite . The traditional production process of cryolite is the soda ash-fluoroaluminic acid method. First, hydrofluoric acid is reacted with aluminum hydroxide to form fluoroaluminic acid, and then reacted with soda ash to form cryolite. The chemical reaction formula is as follows: [0003] <chemistry num="001"> <chem file="03118447_cml001.xml" / > < / chemistry> [0004] <chemistry num="002"> <chem file="03118447_cml002.xml" / > < / chemistry> [000...

AI Technical Summary

Problems solved by technology

The disadvantages of this process are: due to the high temperature required for the reaction, the reaction of synthesizing fluoroaluminic acid is violent, the operation is not easy to control, and accidents of leaking tanks and hurting people are prone to occur; and because the entire production is carried out under acidic conditions, and The temperature is high, the equipment is severely corroded, and acid waste residue is produced, polluting the environment

[0011] The disadvantages of this process are: (1) using sodium fluorosilicate and dilute ammonia water to react white carbon black seed crystals, since sodium fluorosilicate is a solid phase, the reaction is not complete, and the content of sodium ions in the prepared seed crystals Larger, poor seed crystal quality, and there are solid particles, poor transparency, whitish color

(2) The white carbon black slurry obtained by using sodium fluorosilicate to make seed crystals has more crystals of sodium fluoride, which is inconvenient for washing and separation, which greatly affects the purity of white carbon black

(3) The prepared cryolite molecules are relatively high, generally above 2.8, and cannot be adjusted downwards, so they can only be used in the slotting stage of electrolytic aluminum production

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