Hierarchically recycling method of waste aluminum etching liquid

Abstract

The invention discloses a method for hierarchically recycling phosphoric acid, acetic acid and nitric acid from an aluminum scrap etching solution, which comprises the following steps of volatilizingthe acetic acid and nitric acid in the aluminum etching solution by reduced pressure distillation, and recycling by condensation; adding an additive into the residual phosphoric acid solution, crystallizing, washing, dissolving and the like to obtain the high-purity phosphoric acid; adding the sodium acetate into the collected distillate containing the acetic acid and nitric acid, and distilling to collect the acetic acid; and carrying out vacuum concentration, crystallization, filtration and drying on the acetic acid distilled liquid to obtain a sodium nitrate finished product. The reusable high-purity phosphoric acid is obtained by methods of distillation, concentration, recrystallization and the like, the acetic acid is recycled, and the nitric acid is converted into the available sodium nitrate, so that the useful components in the aluminum etching solution are reasonably and effectively utilized, and the resource waste and the environmental pollution are avoided. The method is high in recycling rate and high in operability, can meet the large-scale production, realizes the resource cyclic utilization to the maximum extent, and avoids the direct emission of the aluminum etchingsolution.

Description

technical field [0001] The invention relates to a separation and recycling method of ternary component waste acid etching solution, in particular to a classification recycling method of waste aluminum etching solution. Background technique [0002] With the rapid development of thin film transistor liquid crystal display, my country has grown into the world's largest display production base. The etching process is an indispensable key step in the preparation of liquid crystal displays. The etching solution used is mainly strong acid waste liquid. Under the severe environmental protection situation today, if these waste liquids cannot be treated by effective methods It poses a great challenge to the survival of enterprises. Therefore, it is imperative to effectively recycle these resources. [0003] The waste aluminum etchant is the waste liquid produced by wet etching of TFT-LCD to make aluminum wires, and mainly contains phosphoric acid, nitric acid, acetic acid and a sma...

AI Technical Summary

Problems solved by technology

[0004] At present, the treatment method for waste aluminum etching solution is acid-base method, which consumes a lot of energy, and the phosphoric acid, acetic acid and nitric acid in it have not been effectively used, and the waste of resources is serious.

Extraction method, this treatment method needs to consume a large amount of extractant, and the treatment effect is poor, it takes a long time, and there are difficulties in actual operation

In a large number of methods of treating waste aluminum etching solutions by distillation, only phosphoric acid, or phosphoric acid and acetic acid are recovered, and the purity of phosphoric acid is not high, and acetic acid and nitric acid are not effectively utilized

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