Treatment method for producing sodium silicofluoride as byproduct in inorganic fluoride production process

Abstract

The invention relates to a treatment method for producing sodium silicofluoride as a byproduct in an inorganic fluoride production process. The technical scheme comprises the following steps: reacting the sodium silicofluoride with a sodium hydroxide solution, filtering, and drying a filter cake so as to obtain sodium fluoride; reacting a filtrate with a fluoride-containing acidic mother liquid so as to generate silica and a sodium chloride solution, filtering, and adding the generated silica in a fluosilicic acid solution containing hydrofluoric acid for reacting the silica with the hydrofluoric acid so as to prepare fluosilicic acid; and reacting the fluosilicic acid with the sodium chloride solution so as to prepare the sodium silicofluoride. The sodium silicofluoride can be used for producing cryolite, and the generated hydrochloric acid solution can be circularly used for producing the cryolite with a clay bittern method. In the method, the used raw materials are fluoride-containing solids and liquids which are byproducts in the fluoride production process, the production process is simple, and the raw material utilization is high; the content of the produced inorganic fluoride salt impurity is low, which meets the national standard; and by using the method, waste is turned into wealth, and the production idea of resource comprehensive utilization as well as energy conservation and environmental protection is achieved.

Description

technical field [0001] The invention relates to a treatment method for sodium silicofluoride by-product in the production process of inorganic fluorides. Background technique [0002] Climate warming, environmental pollution and resource depletion are prominent problems facing the world today. With the development of the fluorine chemical industry and the gradual depletion of fluorine resources, in order to achieve sustainable development, it is necessary to solve various problems of resource sources and environmental governance. ", the fluorine chemical industry can achieve long-term development. [0003] With the rapid development of the electrolytic aluminum industry, the demand for fluoride salts has increased sharply. Making full use of low-grade fluorine-containing resources, reducing fluorine loss in the production process of fluorine chemicals, developing high-performance fluorides and effectively recycling downstream fluorine resources are the future. The inevitab...

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Problems solved by technology

However, due to incomplete separation or pyrolysis during the production process, the by-product sodium fluoride will contain a large amount of silicon dioxide (i.e. silicon sodium fluoride), such as in the production of polysilicon by pyrolysis of fluorosilicic acid / sodium fluorosilicate Due to the limitation of reaction conditions during pyrolysis, the main components of pyrolysis residue are sodium fluoride and silicon dioxide; another example is the production of cryolite co-production of silica by fluosilicic acid / sodium fluosilicate method due to the relatively low solubility of sodium fluoride Small, resulting in the ammonolysis of silica slurry mixed with sodium fluoride solids, insufficient separation and a large amount of sodium silicofluoride by-product

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