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Preparation method of hydrofluoric acid

A technology of hydrofluoric acid and fluorosilicic acid, applied in the directions of fluorine/hydrogen fluoride, silicon oxide, etc., can solve the problems of complex hydrofluoric acid process, non-renewable fluorite, and high raw material cost, and achieve easy popularization and application and good economic value. and social value, the effect of reducing production costs

Inactive Publication Date: 2008-03-05
DO FLUORIDE CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional process of hydrofluoric acid production uses fluorite and sulfuric acid as raw materials. Fluorite is a non-renewable important strategic resource, which is protected by the state and restricted from mining.
And the existing preparation process of hydrofluoric acid is comparatively complicated, and the raw material cost is high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The preparation method of hydrofluoric acid of the present invention, take fluosilicic acid as raw material, comprises the following steps:

[0023] (1) reacting a fluorosilicic acid solution with a concentration of 15% and a solid sodium sulfate for 30 minutes, filtering to obtain a sodium fluorosilicate solid, and treating and discharging the sulfuric acid waste liquid;

[0024] (2) Decompose sodium fluorosilicate at 350°C for 4 hours to generate sodium fluoride solid and silicon tetrafluoride gas;

[0025] (3) Absorb and hydrolyze silicon tetrafluoride gas with water, filter to obtain 15% fluorosilicic acid solution, return to make sodium fluorosilicate, wash and dry the silicon dioxide solid to obtain white carbon black;

[0026] (4) React the sodium fluoride solid generated in step (2) with 98% sulfuric acid at a temperature of 150°C for 5 hours, the gas produced is condensed and rectified to obtain hydrofluoric acid, and the solid sodium sulfate is returned to pro...

Embodiment 2

[0028] The preparation method of hydrofluoric acid of the present invention, take fluosilicic acid as raw material, comprises the following steps:

[0029] (1) Reacting a 25% fluosilicic acid solution and sodium sulfate solid for 30 minutes, filtering to obtain the sodium fluosilicate solid, and treating and discharging the sulfuric acid waste liquid;

[0030] (2) Decomposing sodium fluorosilicate at a temperature of 450° C. for 4 hours to generate sodium fluoride solid and silicon tetrafluoride gas;

[0031] (3) Absorb and hydrolyze silicon tetrafluoride gas with water, filter to obtain 25% fluorosilicic acid solution, return to make sodium fluorosilicate, wash and dry the silicon dioxide solid to obtain white carbon black;

[0032] (4) React the sodium fluoride solid generated in step (2) with 99% sulfuric acid at a temperature of 250°C for 3 hours, the gas produced is condensed and rectified to obtain hydrofluoric acid, and the solid sodium sulfate is returned to produce fl...

Embodiment 3

[0034] The preparation method of hydrofluoric acid of the present invention, take fluosilicic acid as raw material, comprises the following steps:

[0035] (1) react 35% fluorosilicic acid solution and sodium sulfate solid for 30 minutes, filter to obtain sodium fluorosilicate solid, and discharge the sulfuric acid waste liquid;

[0036] (2) Decomposing sodium fluorosilicate at a temperature of 750° C. for 2 hours to generate sodium fluoride solid and silicon tetrafluoride gas;

[0037] (3) Absorb silicon tetrafluoride gas with water and hydrolyze it, filter to obtain 35% fluorosilicic acid solution, return to make sodium fluorosilicate, wash and dry the silicon dioxide solid to obtain white carbon black;

[0038] (4) React the sodium fluoride solid generated in step (2) with 100% sulfuric acid at a temperature of 300°C for 2 hours, the gas produced is condensed and rectified to obtain hydrofluoric acid, and the solid sodium sulfate is returned to produce fluorosilicic acid s...

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Abstract

The process of producing hydrofluoric acid with fluorosilicic acid and magnesia as material includes the following steps: 1. reacting fluorosilicic acid solution and solid sodium sulfate for 10-60 min, filtering to obtain solid sodium fluosilicate, and treating waste sulfuric acid before draining; 2. decomposing sodium fluorosilicate at 300-800 deg.c for 1-5 hr to produce solid sodium fluoride and gaseous silicon tetrafluoride; 3. absorbing gaseous silicon tetrafluoride with water and hydrolyzing, and filtering to obtain fluorosilicic acid solution returned to the step 1 and silica, washing and drying to obtain carbon white; and 4. reacting the solid sodium fluoride and 98 % over sulfuric acid, condensing the produced gas condensing and rectifying to obtain hydrofluoric acid, and returning solid sodium sulfate to the step 1. The present invention utilizes fluorosilicic acid as side product from phosphate fertilizer production as material, and has low cost and environment friendship.

Description

technical field [0001] The invention relates to a method for preparing hydrofluoric acid, in particular to a method for preparing hydrofluoric acid using fluosilicic acid as a raw material. Background technique [0002] Hydrofluoric acid is used in the production of fluorine refrigerants, fluorine-containing resins, organic synthesis (polymerization, condensation, alkylation) to promote the fusion of fluororesins, flame retardants and dye synthesis; to produce organic or inorganic fluorides, such as fluorocarbons , aluminum fluoride, uranium hexanitride, cryolite, etc.; corrosion and engraving of glass, electroplating, reagents, fermentation, ceramics treatment, catalysts in the petroleum industry, manufacture of frosted bulbs, sand removal of metal castings, removal of graphite ash , cleaning of metals (pickling copper, brass, stainless steel, etc.) Acids are a raw material for rocket fuel and additives, and are the main raw material for making elemental fluorine. The tra...

Claims

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Application Information

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IPC IPC(8): C01B7/19C01B33/113
Inventor 李世江侯红军杨华春皇甫根利张梅刘海霞闫春生
Owner DO FLUORIDE CHEM CO LTD
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