SU1101411A1 - Method for producing cryolite - Google Patents

Abstract

1. A method for producing a cryolite, including treating fluorine-silicon-containing gases with a soda solution, treating the resulting solution with an aluminum-containing reagent, separating and drying the product, characterized in that fluoroaluminium sulfate-containing solution and processing are used to increase the process rate and fluorine content in the product at a pH of 2.0-4.0. 2. The method according to claim 1, characterized by the fact that as the fluoroaluminium sulphate-containing solution take waste production of aluminum fluoride .1 (L with

Description

This invention relates to organic chemistry and can be used in the manufacture of cryolite.

A known method for producing cryolite involves treating fluorine-silicon-containing gases with water and feeding the resulting hydrofluoric acid to prepare solutions of sodium and aluminum fluorides, from which cryolite is obtained in SO-SSC. The yield of fluorine to cryolite is 71, 73% 11.

The closest in technical essence is a method of obtaining cryolite, which includes treating fluorine-silicon-containing gases with a soda solution, separating the silica precipitate, treating the resulting solution with sodium aluminate solution, followed by separating and drying the product. The fluorine content in the cryolite is 49.8-51.3%, and the cryolite deposition rate is 1.2-1.7 m / hr23.

The purpose of the invention is to increase the process speed and the fluorine content in the product.

The goal is achieved by the method of producing a cryolite, which includes treating fluorine-silicon-containing gases with a soda solution, processing the resulting solution with an aluminum-containing reagent, separating and drying the product, using aluminum fluoro-sulphate-containing solution and processing at a pH of 2.0-4, 0

At the same time, as a fluoroaluminium sulfate-containing solution, aluminum fluoride production waste is taken.

When the pH value of the solution is less than two, the fluorine content in the product decreases to 52-53% and the rate of cryolite precipitation to 0, m / h. The yield of fluorine and aluminum in the product is, respectively, up to 75 and 86%. When the pH value of the solution is more than 4, the fluorine content in the product decreases to 48-51% and the precipitation rate of cryolite to 11.5 m / h. At the same time, the content of silicon dioxide in the product rises sharply to 1.5-3.5%.

The table shows data on the quality of cryolite, the deposition rate, and the use of fluorine and aluminum in the product, depending on the pH of the solution during processing. It can be seen from the table that if the treatment of the gas cleaning solution is carried out at a pH value of 1.5, then the fluorine content in the product and the rate of cryolite precipitation decrease to 53.2% and 0.7 m / h, respectively. The use of fluorine and aluminum in the product, respectively, is reduced to 75.5 and 86.3.

115

99.3 115 99.3 115 99.3 99.3 115 99.3 115

53.2

18.5

18.3 54.5 21.5 17.7 23.6 17.2 55.5 54.8 16.4 25.3 51.2 15.5 26.4

The method is carried out as follows.

A 2-5% soda solution in the amount of 110-300% of the stoichiometrically required fluorine is fed to the irrigation of the apparatus, to which fluorine-silicon-containing gases enter. The solution obtained from the apparatus is mixed with SO-gS C for 30-60 minutes with an aluminum-fluoro-containing solution containing,%: Afe 0.3-3.5, F 0.6-7.5j SO 0.3-1.2, SiOj 0.2-0.7, and carry out the process at a pH of 2-4. Cryolite formed by mixing after separation from the solution is substantial. Part of the mother liquor is used to prepare a solution of soda directed to absorption, fluorine-containing gases, the remaining part is removed from the process.

PRI me R. To irrigate the gas cleaning apparatus, which receives 50,000 m of gas with a concentration of 10 g / m

Table continuation

HF, 1.5 g / m 5iF4 serves 56,650 kg of a solution containing 1,700 kg of NajCO, Which is 115% of the stoichiometrically necessary amount for bonding fluorine. The solution obtained from the gas cleaning apparatus in the amount of 56610 kg is mixed for 30 minutes with 66990 kg of fluoroaluminium-containing solution and treated with a solution pH value of 3. After separation from the cryolite solution by precipitation at a speed of 3.5 m / h and filtering the thickened suspension cryolite to its drying receive 2677 kg of product with a content of 55.5% F; 17.2% At; 23.6% Na; 0.7% 5; 0j; 0.6% 90. Part of the stock solution containing 0.4% F; 0.16% Na; 0.007% A6 is sent to the gas cleaning system, the rest is withdrawn from the process. The economic effect from the introduction of the proposed method will be 300 thousand rubles. in year.

Claims (2)

1. METHOD FOR PRODUCING CRYOLITE, including treating fluorosilicon-containing gases with a soda solution, treating the resulting solution with an aluminum-containing reagent, separating and drying the product, characterized in that, in order to increase the rate of the process and the fluorine content in the product, a fluorine-aluminum sulfate-containing solution and processing are used lead at a pH of a solution of 2.0-4.0. 2. The method of Pop. 1, characterized in that the aluminum fluoride production waste is taken as a fluoroaluminium sulfate-containing solution. PY0P ^by ns ^No. > \