SU125550A1 - Hydrothermal method of producing hydrofluoric acid - Google Patents

Description

There are known methods for producing hydrofluoric acid by hydrothermal decomposition of fluorine-containing raw material - fluorspar with superheated water vapor in the presence of addition of sesquioxides. However, all these methods, based on the use of fluorspar as a feedstock, require high temperatures in the range of 1200-1300 °, which makes instrumentation formatting difficult, low-intensity and associated with high fuel and steam consumption.

In order to eliminate the noted drawbacks, a hydrothermal method for the production of hydrofluoric acid is proposed, with;: the fact that it is heated to 800-850 ° C from alkaline silicon fluoride and part, for example, 2/3 of recycled alkaline ferro (aluminum) silicate cake. , treated with superheated water to 450 °. The hydrogen fluoride released is condensed with the water vapor. Another part of the guardianship is treated with fluorosilicic acid or fluorine-containing gases to produce sodium fluorosilicate, which is recycled to the production cycle. Squash is carried out as follows. Wet alkaline silicofluoride is mixed with a part, for example 2/3, of recycled crushed alkaline ferro (alumino) silicate custody, obtained after thermohydrolytic HF release, for example, from 2Na2O 2SiO2 - RegOz, heated to 800-850 ° C and passed through sintered mixture water vapor overheated to -450 °. Fluorine released with this excess condenses with an excess of water vapor to form a water solution of hydrofluoric acid with an insignificant admixture of l, 5 / oH2SiF6.

The fluoro yield is.

The obtained sinter is thoroughly crushed and divided into two parts, one part 2/3 is directed to the interaction with a solution of hydrofluoric acid or directly to the absorption of fluoroAO 125550

gases with the formation of a mixture of Na2SiF6 and Fe2Oz in the bottom phase and a flocculent silica gel that floats on the surface. After 10-15 minutes sediment and decantation of a part of the solution with silica gel, precipitate is precipitated from the remaining pulp, content - 75-80Vo Na2SiF: (on a dry basis) and 25-20; Vo moisture. The output of fluorine 90%.

The obtained Na2SiF6 mixed with FeaOalAbOa) is mixed with another part of 1/3 of the final sinter and sent to the next thermohydrolysis operation.

The precipitate of Na2SiF6 obtained after purification of hydrofluoric acid is recycled, so that the process is closed and only excess SiO2 is removed from the cycle, which can be used, for example, as a filler.

The total yield of acid in fluorine throughout the process is 90%.

Subject invention

The hydrothermal method of obtaining hydrofluoric acid from a mixture of fluorine-containing raw materials in the presence of additives of sesquioxides using superheated water vapor, is different in that, in order to reduce the process temperature and save alkali consumption and additives, fluorine-containing raw materials are used up to 850 ° batch of alkaline silicofluoride and part, for example, 2/3 of alkaline ferro (alumino) silicate cake, which is treated with water heated up to –450 ° Lara.