Method for producing ammonium bifluoride through fluorine-containing waste etching liquid

Abstract

The invention discloses a method for producing ammonium bifluoride through fluorine-containing waste etching liquid. The method includes the following steps that (1) the fluorine-containing waste etching liquid is subjected to impurity removing through an impurity removing device, and sulfate ions, chloride ions and nitrate ions in the waste liquid are removed; (2) the waste liquid after impurity removing is added into a reaction kettle, liquid ammonia is led into the reaction kettle till new precipitate cannot be generated, heating is carried out, unreacted ammonia gas is discharged and recycled, liquid and the precipitate are added into a filter, filtered and separated, and filtered liquid and filtered residues are obtained; (3) hydrofluoric acid is added into the filtered liquid obtained in the step (2) till the pH value is not changed, the mixture is evaporated, crystallized, washed, dried and smashed, and the ammonium bifluoride product is obtained. The method is suitable for fluorine-containing waste etching liquid with the high fluorine content (the hydrofluoric acid content is larger than or equal to 5 wt%), the waste liquid after impurity removing is treated and recycled to obtain the ammonium bifluoride product; the fluorine-containing waste etching liquid is effectively subjected to secondary utilization, pollution of the waste liquid to the environment is reduced, and the industrial value is improved.

Description

technical field [0001] The invention belongs to the field of fluorine-containing waste liquid treatment, in particular to a method for producing ammonium bifluoride from fluorine-containing etching waste liquid. Background technique [0002] The fluorine-containing etching waste liquid with relatively high fluorine content contains hydrofluoric acid, fluorosilicic acid, and many impurities such as acid radical ions. At present, fluorine-containing etching waste liquid is basically unused, and direct discharge will not only cause pollution, but the waste liquid after simple treatment has no use value, and this link lacks use value in industrial production. Contents of the invention [0003] The invention provides a method for producing ammonium bifluoride from fluorine-containing etching waste liquid, which is used to solve the defects in the prior art. [0004] The present invention is achieved through the following technical solutions: [0005] The method for producing ...

AI Technical Summary

Problems solved by technology

At present, fluorine-containing etching waste liquid is basically unused, and direct discharge will not only cause pollution, but the waste liquid after simple treatment has no use value, and this link lacks use value in industrial production

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