Method for recycling waste gas containing fluorine

Abstract

The invention relates to a method for recycling waste gas containing fluorine, belonging to the technical field of chemical industrial production. The method comprises the following steps: absorbing silicon tetrafluoride by an ammonium fluoride solution to produce ammonium fluosilicate, then ammoniating the ammonium fluosilicate to reduce the ammonium fluosilicate to ammonium fluoride, and simultaneously, generating precipitate silica (silica white); after separating the precipitate silica (silica white), by using the changing solubility of ammonium fluoride resulting from the change of temperature, separating the ammonium fluoride by cooling and crystallization; simultaneously, in order to ensure water balance of the overall system and diversification of products, enabling part of the ammonium fluosilicate and potassium chloride (or potassium sulfate) to carry out metathetical reaction to generate potassium fluosilicate precipitate and ammonium chloride (or ammonium sulfate); and after the precipitate silica is separated, concentrating and crystallizing a mother solution to obtain ammonium chloride (or ammonium sulfate) fertilizer. The invention is mainly applied to the fertilizer production industry.

Description

technical field

[0001] The invention relates to a method for recycling fluorine-containing waste gas, which belongs to the technical field of inorganic chemical industry production, and specifically relates to a method for producing potassium fluorosilicate and white carbon black by using fluorine-containing waste gas. Background technique

[0002] In the process of producing ordinary calcium superphosphate, wet-process phosphoric acid, heavy calcium and other phosphorus chemical processes from phosphorous rock, part of the fluorine and silicon in the phosphorous rock escapes in the form of silicon tetrafluoride, forming fluorine-containing waste gas. Most of the existing treatment is to absorb waste gas with water to generate silica gel and fluosilicic acid, and then react fluosilicic acid with sodium chloride (or sodium sulfate) to generate sodium fluosilicate and hydrochloric acid (or sulfuric acid). Because silica gel contains impurities such as phosphorus and fluorine, ...