Method and device for treating fluorine-containing waste water

Abstract

The invention provides a method and a device for treating fluorine-containing waste water. In the method, a solid-liquid fluidized bed is used as a crystal reactor; a certain amount of calcium fluoride seed crystal is added into the reactor; the fluorine-containing waste water and a calcium-containing precipitator are delivered into a treatment device of the solid-liquid fluidized bed in a reacting ratio to ensure that fluorinions are precipitated on the surface of the calcium fluoride seed crystal; the prepared sand-shaped calcium fluoride precipitated slurry after precipitation is reclaimed; and primarily treated water is subjected to flocculent precipitation further to meet the emission standard. By adopting the method, most fluorinions can be precipitated in the crystallization and precipitating process in the fluidized bed, the generated sand-shaped calcium fluoride has low content of water and high content of calcium fluoride and can be used as fluorine resources for recycling; and in the flocculent precipitating process of the primarily treated water, the consumption of the fluorescent is low, and the yield of slurry is low. Therefore, the comprehensive cost for waste watertreatment is low.

Description

Technical field: [0001] The invention belongs to the field of environmental engineering, and relates to a method and a device for precipitating and separating fluorine ions in the form of calcium fluoride from fluorine-containing wastewater, which can effectively remove fluoride ions in wastewater and recycle calcium fluoride precipitation. Background technique [0002] Wastewater discharged from industries such as chemical industry, non-ferrous metallurgy, glass, electronics, and electroplating often contains high concentrations of fluoride, causing fluorine pollution in the water environment. Research on fluorine-containing wastewater treatment technology has always been an important topic in the field of environmental protection at home and abroad. At present, there are mainly lime neutralization precipitation method and coagulation precipitation method in domestic and foreign fluorine-containing industrial wastewater treatment methods. [0003] The lime neutralization pr...

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Problems solved by technology

In actual operation, colloidal CaF is easily produced during lime neutralization and precipitation. 2 , so that the method has the following problems: (a) colloidal CaF 2 Sedimentation and sedimentation are difficult to separate, making the effluent F - The concentration is unstable, usually F in the wastewater after treatment - It can only be reduced to 20-30mg / L, which cannot meet the requirements of the first-level standard of GB8979-96 "Integrated Wastewater Discharge Standard"; (b) CaF 2 The sediment has a high moisture content and cannot be recycled as a product, and it is easy to cause secondary pollution after storage

This method has a good defluorination effect, but there are the following problems: (a) the process requires a narrow range of pH value at the dosing point, and the fluoride ion removal effect is greatly affected by operational factors such as stirring conditions and settling time, making production It is difficult to maintain long-term and stable operation; (b) Due to the loose flocs, the sludge clarification time is longer, the sludge volume is large, the moisture content is high, and the cost of flocculants is high, which affects the wide application of this method

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