Method for producing high-quality sodium fluoride from fluorine-containing wastewater as raw material

Abstract

The invention discloses a method for producing high-quality sodium fluoride from fluorine-containing wastewater as a raw material. The method comprises the following steps: directly adding excessive sodium carbonate into the fluorine-containing wastewater to completely crystallize and separate fluorine in the solution in a mode of sodium fluoride, or firstly, adding amino into the fluorine-containing wastewater so as to obtain an ammonium fluoride solution, or firstly, precipitating and enriching the fluorine in the fluorine-containing wastewater, secondly, converting a precipitated and enriched product into an ammonium fluoride solution by using an ammonium salt solution, adding excessive sodium carbonate into the ammonium fluoride solution to completely crystal and separate the fluorine in the mode of sodium fluoride, and filtering so as to obtain sodium fluoride filter cakes and a post fluorine precipitation liquid; and washing the sodium fluoride filter cakes by using the ammonium fluoride solution, drying so as to obtain a high-quality sodium fluoride product of which the purity is up to 99.25% or greater, crystallizing the post fluorine precipitation liquid to recycle sodium carbonate in the post fluorine precipitation liquid, further desalting a sodium carbonate crystallization mother liquid, and recycling reclaimed water. The method has the advantages of being simple and convenient to operate, high in fluorine recycling rate, low in production cost, good in sodium fluoride product quality, free of fluorine-containing waste and the like.

Description

technical field [0001] The invention belongs to the fields of chemical industry and metallurgy, and in particular relates to a method for producing high-quality sodium fluoride by using fluorine-containing wastewater as a raw material. Background technique [0002] Sodium fluoride is an important chemical raw material, widely used in chemical industry, metallurgy, wood preservatives, agricultural pesticides, brewing fungicides, pharmaceutical preservatives, welding flux, alkaline zincate galvanizing additives and enamel , Paper industry and other industries. At present, the main production methods of sodium fluoride are: melting leaching method, neutralization method, sodium fluorosilicate method, ion exchange method, etc. [0003] The immersion method is to calcinate fluorite, soda ash and quartz sand at a temperature of 800-1000 ° C, then leaching with water, and then evaporate, crystallize, and dry to obtain the finished product of sodium fluoride; the neutralization met...

AI Technical Summary

Problems solved by technology

Because the concentration of fluorine in the solution is low, the production process of sodium fluoride requires a large amount of evaporation and concentration, which is economically uneconomical

At present, low-concentration fluorine-containing wastewater at home and abroad, and complex fluorine-containing wastewater are generally treated by lime precipitation, which not only causes a serious waste of fluorine resources, but also produces a large amount of fluorine-containing solid waste