Treatment method of waste etching liquid

Abstract

The invention provides a treatment method of waste etching liquid. The method comprises the following steps: adding the waste etching liquid into an electrolysis device for electrolysis, with the anode material of the electrolysis device being iron or iron alloy; and after electrolysis, dissolving the anode to generate ferrous phosphate, adding an oxidizing agent into the obtained ferrous phosphate solution, then carrying out solid-liquid separation, washing and drying to obtain iron phosphate. According to the treatment method of the waste etching liquid, the iron phosphate is prepared from the hazardous waste, namely the waste etching liquid, through a pollution-free electrolysis process with mild reaction conditions, so that the problems of low yields, high cost, high energy consumption and the like in the traditional processes of treating the waste etching liquid by adopting distillation, extraction and other processes are solved; the treatment method disclosed by the invention is simple in process, low in energy consumption, good in treatment effect, relatively fine in product particles, low in production cost, easy to industrialize and high in added value of products, and has very high economic benefits and environmental benefits.

Description

technical field [0001] The invention relates to the technical field of waste treatment, in particular to a treatment method for waste etching solution. Background technique [0002] Thin Film Transistor Liquid Crystal Display (TFT-LCD) has become the most widely used, fastest growing and largest investment display industry in the world. The waste etchant is produced in the wet etching process of the TFL-LCD production process, in order to dissolve and remove the film surface not covered by the photoresist, and finally form a circuit board with a specific shape. [0003] Waste etching solution is also produced in the semiconductor manufacturing industry, which is a mixture of phosphoric acid, nitric acid and acetic acid in a certain proportion. It is a hazardous waste with strong acidity and corrosiveness. Direct contact with human body surfaces will cause burns. If it is directly discharged into the environment, it contains a large amount of N and P elements, which will cau...

AI Technical Summary

Problems solved by technology

If it is directly discharged into the environment, it contains a large amount of N and P elements, which will cause eutrophication of water bodies and cause harm to aquatic animals and plants. It is difficult to dispose of it economically and effectively, so it is necessary to find a green, economical and effective method to recycle the waste etching solution

[0004] Disclosed in the prior art is a method for reclaiming phosphoric acid in waste aluminum etching solution. It utilizes the large difference in boiling point and volatility of phosphoric acid, nitric acid, and acetic acid, and uses distillation or vacuum distillation to combine phosphoric acid, nitric acid, and acetic acid. Separation, the recycling of the mixed acid solution is realized by methods such as concentration and crystallization. This method has the advantage of strong operability and can meet the needs of large-scale production, but it needs to consume a lot of heat, high energy consumption, maintenance of distillation equipment and It occupies a large area, the processing process is cumbersome and complicated, the output is low, and the product purity is not high

[0005] The prior art also discloses a method for recovering phosphoric acid by extraction, in which an extractant containing trialkyl phosphate is mixed with a mixed acid solution to achieve the purpose of extracting phosphoric acid, and the extract containing acetic acid and nitric acid is stripped, The extract can be recycled. The advantage of this method is that it can selectively realize the recovery of phosphoric acid in the mixed acid solution, but it will use a large amount of organic extractant, and the process is complicated when separating nitric acid and acetic acid. The remaining nitric acid and acetic acid have no If it is effectively treated, it will still cause environmental pollution, and the cost is high, the device occupies a large area, and it is difficult to deal with the remaining organic solvents in the end.

[0006] The current treatment methods for waste etching solution mostly use methods such as distillation, neutralization, extraction, regeneration, and crystallization. For example, Samsung and other large electronic companies currently mostly use extraction methods for treatment, and these methods often have high energy consumption. Low output, high cost, complicated process, difficult process control, etc.

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