Processing method for fluorine ions in cryolite mother liquor prepared through sodium fluorosilicate process

Abstract

The invention discloses a processing method for fluorine ions in cryolite mother liquor prepared through a sodium fluorosilicate process. The processing method comprises the following steps: naturallysettling the cryolite mother liquor prepared through the sodium fluorosilicate process and then feeding into a regulating reservoir, adding calcium hydroxide slurry into the regulating reservoir while stirring till pH value in the regulating reservoir is 4-6, and statically settling, thereby acquiring primary treatment mother liquor; introducing the primary treatment mother liquor into a flocculation basin, adding a flocculating agent into the flocculation basin while stirring, uniformly mixing and then statically settling, thereby acquiring secondary treatment mother liquor; introducing thesecondary treatment mother liquor into an adsorption tank, adding acid for regulating pH to 3-5, adding an adsorbent while stirring, uniformly mixing and then statically settling, thereby acquiring atreating fluid with fluorine ion concentration less than or equal to 0.5mg / L. The processing method for fluorine ions disclosed by the invention has the advantages of high processing efficiency and simple, mature, practical, economical and reasonable method.

Description

technical field [0001] The invention relates to the technical field of fluorine-containing wastewater treatment, in particular to a method for treating fluoride ions in cryolite mother liquor produced by sodium fluorosilicate method. Background technique [0002] Cryolite is mainly used as a co-solvent for aluminum smelting, and can also be used as a crop insecticide, enamel opalescent agent, opacifying agent and flux for glass and enamel production, wear-resistant filler for resin rubber, and can also be used for ferroalloy and boiling steel production. Cryolite has a small amount of natural deposits. At present, the world's aluminum smelting industry mainly uses artificial cryolite. At present, the industrial production methods of artificial cryolite mainly include soda fluoroaluminic acid method, clay brine method, and sodium fluorosilicate to produce cryolite and co-produce white Carbon black, etc. These methods, especially the mother liquor of sodium silicate to produc...

AI Technical Summary

Problems solved by technology

The process is simple and convenient, and the cost is low, but the calcium fluoride precipitate generated in the commonly used calcium hydroxide precipitation defluorination method will be wrapped in Ca(OH) 2 The surface of the particle, so that it cannot be fully utilized, so it is necessary to add an excess of Ca 2+ , but a large amount of calcium salt is mixed into the sludge, which not only increases the sludge production, but also reduces the purity of the fluorine-containing sludge. At the same time, the fluorine content in the treated wastewater is more than 20mg / L, which is difficult to meet the national discharge standard

Flocculation-sedimentation method tends to generate very fine particles with small specific gravity and high viscosity during the process of wastewater treatment, and it is colloidal during the sedimentation process, so separation is difficult, which not only makes it difficult for wastewater to meet the standard, but also produces sludge with high moisture content, which is difficult to recycle.