Method for reclamation of waste acid in hydrofluoric acid etching process

Abstract

The invention discloses a method for reclamation of waste acid in a hydrofluoric acid etching process. The method for reclamation of the waste acid in the hydrofluoric acid etching process belongs to the technical field of a method for reclamation and recovery of the waste acid in the photovoltaic industry and in a semiconductor circuit board manufacturing process, and comprises the steps of utilizing a hydrofluoric acid capture agent to convert hydrofluoric acid in the waste acid into fluosilicic acid; further feeding a fluosilicic acid capture agent to convert fluosilicic acid into fluosilicate; carrying out a distillation and concentration process on remaining acid liquor, distilling and concentrating remaining acid, and obtaining acid liquor same as a raw material which can be sold or reused in the process; further alkalifying and desiliconizing the fluosilicate to form reclamed silicon dioxide and fluoride salt. The fluoride salt can further regenerate the hydrofluoric acid which can be returned to the process so as to be recycled, and the waste acid liquor is fully reclaimed, so that the problem of waste acid processing in the photovoltaic industry is solved, and the effects of full reclamation and cyclic utilization are achieved.

Description

technical field [0001] The invention relates to a method for recycling waste acid in a hydrofluoric acid etching process; it belongs to the technical field of methods for recycling waste acid in the photovoltaic industry and semiconductor circuit board production process, and specifically belongs to the photovoltaic industry and semiconductor circuit board production. The technical field of the method of recovering hydrofluoric acid from hydrofluoric acid mixed acid waste liquid in hydrofluoric acid waste liquid such as etchant used in circuit formation by first electroplating and then etching in the process. Background technique [0002] The hydrofluoric acid etching process is mainly used in the etching of silicon and silicon dioxide, and the discharged waste acid is mainly compounds such as fluosilicic acid, hydrofluoric acid and their mixed acids; the main reactions are: [0003] [0004] In order to control the etching process, it is necessary to match the amount of ...

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Problems solved by technology

[0005] 1. The cost of the mixed acid detection device is high, it is easy to be interfered and cause misjudgment blind spots, and there are troubles in operation, and it is relatively difficult and risky to control the reuse;

[0006] 2. The reuse of mixed acid is not a supplementary raw material for the original production. It needs to increase the transportation pipeline facilities and equipment process adjustments, which increases operational risks and is not accepted by equipment manufacturers and production plants. Therefore, the market for mixed acid reuse is unacceptable;

[0007] 3. There is a risk of accumulation of impurities in the reuse of mixed acid, and there is an operational risk to the production process. Simply removing fluorosilicic acid cannot remove impurities in the etching solution, and it is difficult to control the production quality;

[0008] 4. During the reaction process, water and raw materials will be lost, resulting in a decrease in concentration; there is also water content in the raw materials, and the concentration of the acid etching solution will be lower and lower after mixing, and excessive water cannot be removed, resulting in a large amount of lower concentration Etching waste liquid cannot replace the original etching liquid;

[0009] 5. Since the excessive amount of metal ion trapping agent will affect the etching process, the capture of fluosilicic acid is risky. Excessive entry into etching will affect the production quality, and the risk of fluosilicate corrosion affecting equipment and discharge pipes will increase

Therefore, the current industry is still dominated by neutralization treatment and calcium ion solutions, forming a large amount of calcium fluoride sludge, which cannot be reused, and nitric acid and nitrate radicals cause ecological impact problems and serious environmental protection problems

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