Method for producing ammonium bifluoride by recovering fluorine resource from fluorine-containing silicon slag

Abstract

The invention discloses a method for producing ammonium bifluoride by recovering a fluorine resource from fluorine-containing silicon slag. The method comprises the following steps of: dissolving fluorine-containing silicon slag and an ammonium fluoride solution, cooling an obtained ammonium fluosilicate solution, introducing gas ammonia, and precipitating white carbon black out; filtering and washing to obtain a white carbon black solid and an ammonium fluoride solution; introducing anhydrous hydrogen fluoride into the ammonium fluoride solution, uniformly mixing the anhydrous hydrogen fluoride with the ammonium fluoride solution, and fully reacting till the pH of the solution is 2-4 to obtain an ammonium hydrogen fluoride of which the mass concentration is 21-37 percent; mixing with a crystallized ammonium hydrogen fluoride mother solution, and performing triple-effect evaporation and concentration till the mass concentration of the ammonium hydrogen fluoride is 60-80 percent; feeding into a crystallizer, and cooling and crystallizing for 3-7 hours to obtain an ammonium hydrogen fluoride solid-liquid mixture; and separating to obtain an ammonium bifluoride product and an ammonium bifluoride mother solution. The method has the advantages of low using amount of fluorine hydride, high concentration of ammonium bifluoride, low energy consumption in a concentrating process, low production cost, easiness and convenience for operating, and easiness for realizing industrialization.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a method for recovering fluorine resources in fluorine-containing silicon slag to produce ammonium bifluoride. [0002] Background technique [0003] During the production process of phosphate fertilizer industry, a large amount of fluosilicic acid is produced as a by-product. When anhydrous hydrogen fluoride is produced by using concentrated sulfuric acid as a raw material, a large amount of fluorine-containing silicon slag is produced by-product. Forms exist, including free fluorine and lattice fluorine. How to make good use of the fluorine resource in the fluorine-containing silicon slag is a major subject to be studied. [0004] Ammonium bifluoride is mainly used as glass etchant, chemical reagent, boiler cleaning agent, fermentation industry disinfectant, steel plate surface treatment agent, oil mining plugging agent, fine ceramic filler, etc. [0005] The tradi...

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Problems solved by technology

[0006] Chinese patent 200610017486.5 discloses "a method for producing ammonium bifluoride and co-production of white carbon black", in which white carbon black and ammonium fluoride are prepared from fluorosilicic acid or ammonium fluorosilicate and ammonia water, and the ammonium fluoride solution is concentrated, Pyrolysis produces liquid ammonium bifluoride and ammonia gas. The decomposition temperature is 130-180°C. Liquid ammonium bifluoride is cooled to produce solid ammonium bifluoride. During the process of concentration and decomposition, energy consumption is high, resulting in high energy consumption in the entire production process; and fluorination The concentration of dilute ammonia water produced during the concentration and decomposition of ammonium solution is relatively low, and it is a big problem to recycle, utilize or dispose of it in industrial production

The above three patents all use hydrogen fluoride as a raw material, which requires a large amount of hydrogen fluoride and high production costs