Method and device for treating fluorine-containing waste water using limestone

Abstract

The invention discloses a disposing method and device of fluorine waste water through limestone, which comprises the following steps: adopting natural limestone as raw material; proceeding biochemical reaction to produce soluble calcium salt acid as middle dielectric; reacting soluble calcium salt acid and fluorine ion in the fluorine waste water to form indissolvable calcium fluoride and acid middle dielectric; reacting acid middle dielectric and limestone to produce soluble calcium salt; reacting soluble calcium salt acid and fluorine ion in the fluorine waste water to form indissolvable calcium fluoride and acid middle dielectric; circulating; disposing fluorine waste water until reaching standard. The corresponding disposing device contains reacting pond, circulating pump, neutralizing tower, sediment pond and sludge pond.

Description

technical field [0001] The invention relates to the technical field of industrial wastewater treatment, in particular to a method and a device for treating fluorine-containing wastewater with limestone. Background technique [0002] my country is a big country with rapid development of fluorine chemical industry. It has always attached great importance to the environmental protection treatment of fluorine-containing wastewater. At present, there are two main methods for treating fluoride-containing wastewater: one is the "lime method", which is currently used more commonly. , accounting for more than 90% of the existing treatment devices, its working principle is the lime aqueous solution (Ca(OH) 2 ) after ionization, reacts with fluoride ions in wastewater to generate insoluble calcium fluoride (CaF 2 ), separated from water after sedimentation, the advantage of "lime method" is that the treatment process is simple and the cost is relatively low, so it is widely used, and i...

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Problems solved by technology

[0002] my country is a big country with rapid development of fluorine chemical industry. It has always attached great importance to the environmental protection treatment of fluorine-containing wastewater. At present, there are two main methods for treating fluoride-containing wastewater: one is the "lime method", which is currently used more commonly. , accounting for more than 90% of the existing treatment devices, its working principle is the lime aqueous solution (Ca(OH) 2 ) after ionization, reacts with fluoride ions in wastewater to generate calcium fluoride (CaF 2 ), separated from water after sedimentation, the advantage of "lime method" is that the treatment process is simple and the cost is relatively low, so it is widely used, and its disadvantage is that the solubility of lime aqueous solution is small, and its solubility product Ksp=5.5X10 -6 , and the commonly used lime water is an emulsion containing a large amount of solid particles, with a large amount of slag, so the effective utilization rate when treating wastewater is very low, especially the concentration of fluoride ions in the wastewater treated by this method is still 10 -20mg / L, it is difficult to meet the emission standard requirement of <10mg / L

The second is the "soluble calcium salt method", which is characterized by directly adding soluble calcium salts with high solubility and obtaining calcium ions. The defluorination reaction is fast and the compliance rate of wastewater treatment is very high. As a chemical raw material, calcium salt is relatively expensive, and the treatment cost is greatly increased compared with the lime method. This method is generally suitable for wastewater treatment with small wastewater discharge and low fluorine content.

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