Preparation method of ammonium bifluoride

Abstract

The invention discloses a preparation method of ammonium bifluoride. The method comprises steps as follows: a, dilute ammonia water and ammonium bifluoride mother liquor are mixed to adsorb gas containing fluorine and silicon, and a mixed solution is obtained; b, the mixed solution and filter-press residues obtained in Step d are mixed for slurry making and filter-press separation, and a filtrate and a silica by-product are obtained; c, ammonia is introduced into the filtrate; d, slurry is subjected to filter-press separation, and an ammonium fluoride filtrate and filter-press residues are obtained; e, the ammonium fluoride filtrate is subjected to vacuum concentration; f, concentrated slurry is dissolved, the pH value of the solution is adjusted with hydrogen fluoride, and cooling crystallization is performed; g, ammonium bifluoride crystals are filtered, separated and dried, and the ammonium bifluoride product is obtained. With the adoption of the method, the utilization rate of fluorine and ammonia is increased, the gas containing fluorine and silicon is changed into the ammonium bifluoride product with the high economic value in the phosphoric acid production process, the production cost is low, the economic benefit is significant, meanwhile, the purity and other indexes of the product meet the requirement for superior products, and the method is suitable to be popularized and applied in the field.

Description

technical field [0001] The invention relates to the preparation technology of inorganic fluorine salts in the fluorine chemical industry, in particular to a method for preparing ammonium bifluoride by using a fluorine-containing absorption liquid. Background technique [0002] Ammonium bifluoride is white or colorless transparent orthorhombic crystal, which is easy to deliquesce and agglomerate in the air, and is easily soluble in water. The aqueous solution is strongly acidic and has the sour taste of hydrogen fluoride; it is slightly soluble in alcohol, decomposes in hot water, and sublimes at high temperature. [0003] Ammonium bifluoride is mainly used as glass etchant, preservative, solvent for metal beryllium made of beryllium oxide, chemical reagent, cleaning agent for boiler feed water system and steam generation system, disinfectant for fermentation industry and surface treatment agent for silicon steel plate, manufacturing ceramics and aluminum magnesium Oxidant f...

AI Technical Summary

Problems solved by technology

Ammonium bifluoride prepared by this method has high energy consumption and low product purity

The patent document with the application number 200310104114.2 mentions that the ammonium fluoride filtrate is used to absorb the fluorine-containing gas in the phosphoric acid production process. After the absorption liquid is dephosphorized and neutralized with ammonia, it is concentrated to produce ammonium bifluoride. The decomposition is not complete, and the ammonium bifluoride product with higher purity cannot be obtained

The patent document with application number 201310010638.9 mentions that ammonium fluoride filtrate is used to absorb fluorine-containing gas in the phosphoric acid production process, the absorption liquid is passed through ammonia for neutralization, hydrofluoric acid is used to adjust the pH value of the neutralization liquid and concentrated, and the concentrated liquid is cooled and crystallized to produce Ammonium bifluoride, the crystallization mother liquor is returned to the concentration system. This method uses ammonium fluoride to absorb fluorine-containing gas. The dilute ammonia water obtained in the concentration process cannot be rationally utilized, resulting in high production costs and difficult product purity to meet the requirements of superior products.

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