Method for producing ammonium fluoride by recovering fluorine resources

Abstract

The invention discloses a method for producing ammonium fluoride by recovering fluorine resources. The method comprises the following steps of: dissolving fluorine-containing silicon dregs and ammonium fluoride at the temperature of between 95 and 108 DEG C to obtain a transparent ammonium fluosilicate solution, cooling, introducing ammonia gas until the pH value is between 9.0 and 9.8, precipitating to separate white carbon black out, filtering to obtain a white carbon black solid and an ammonium fluoride solution, and returning the ammonium fluoride solution according to the quantity required by reacting with silicon dregs; mixing the residual ammonium fluoride solution with a mother solution formed by crystallizing ammonium fluoride, and concentrating the mixture in a concentration device until the mass concentration of the ammonium fluoride is between 60 and 80 percent; conveying the ammonium fluoride into a cooling crystallizer, cooling and crystallizing for 4 to 7 hours, and precipitating ammonium fluoride crystals to obtain an ammonium fluoride solid-liquid mixture; and filtering and separating the ammonium fluoride solid-liquid mixture to obtain the ammonium fluoride crystals. By the method, the concentration of the ammonium fluoride can be improved, the energy consumption in the concentration process can be reduced, fluorine in the fluorine-containing silicon dregs is recovered, phosphorite associated fluorine resources are utilized fully, and the pollution of the fluorine-containing silicon dregs to environment is reduced.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a method for producing ammonium fluoride by recovering fluorine resources in fluorine-containing silicon slag. [0002] Background technique [0003] In the process of producing phosphoric acid from phosphate rock, a large amount of silicon tetrafluoride gas is produced. At present, the most commonly used method is to absorb silicon tetrafluoride with water to generate fluorosilicic acid, and then use fluorosilicic acid to produce other products, and recover fluorine associated with phosphate rock. resource. [0004] At present, the methods for producing ammonium fluoride by recovering the associated fluorine resources of phosphate rock are: 200710066136.2 Use fluosilicic acid and ammonia water as raw materials for step-by-step ammoniation reaction, filter, wash, and dry to obtain white carbon black and high-concentration ammonium fluoride mother liquor. 200610017485....

AI Technical Summary

Problems solved by technology

[0005] The above-mentioned technologies all directly use fluosilicic acid and ammonia water as raw materials by-products of wet-process phosphoric acid, and the resulting filtrate has a low concentration of ammonium fluoride, and the energy consumption is high during the concentration process.