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Acid etching silicon wafer waste acid liquid treatment method and system

A processing method and technology of silicon wafers, applied in the direction of calcium/strontium/barium halide, calcium/strontium/barium fluoride, etc., can solve the problems of resource waste and environmental pollution of fluorine ion and fluorosilicate ion

Inactive Publication Date: 2019-08-23
北京环球中科水务科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It may cause other environmental pollution problems, and it is also a waste of fluoride ion and fluorosilicate ion resources

Method used

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  • Acid etching silicon wafer waste acid liquid treatment method and system
  • Acid etching silicon wafer waste acid liquid treatment method and system
  • Acid etching silicon wafer waste acid liquid treatment method and system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0096] Embodiment 1: For the annual production of 3GW crystalline silicon solar cell project, the amount of waste acid solution produced by acid etching silicon wafers is 50m 3 / d, the waste acid solution contains 5.88% fluosilicic acid, 11.1% hydrofluoric acid, 38% nitric acid and 1% hydrochloric acid. This implementation case includes the following steps:

[0097] The steps for preparing sodium fluorosilicate solid: first put the waste acid solution of acid etching silicon wafer (hereinafter referred to as: waste acid solution) into the first-stage crystallization tank, start the stirrer, stir at 200rpm, and then mix 160kg / m 3 Pass the saturated sodium chloride solution into the crystallization tank at a constant speed, keep the reaction temperature at 25°C, and continue to stir for 30 minutes to react. After the reaction, pass the solid-liquid mixed solution into the centrifuge to separate the first filtrate and wet sodium fluorosilicate solid , and then wash and dry the w...

Embodiment 2

[0102] Example 2: Aiming at an annual production of 9GW crystalline silicon solar cell project, the amount of waste acid produced by acid etching silicon wafers is 120m 3 / d, the waste acid liquid contains 8.9% fluosilicic acid, 15.6% hydrofluoric acid, 42% nitric acid and 0.6% hydrochloric acid. This implementation case includes the following steps:

[0103] The steps for preparing sodium fluorosilicate solid: first put the waste acid solution into the first-stage crystallization tank, start the stirrer, stir at 180rpm, and then mix 154.6kg / m 3 Pass the saturated sodium nitrate solution into the crystallization tank at a uniform speed, keep the reaction temperature at 25°C, and continue to stir for 60 minutes to react. After the reaction is completed, pass the solid-liquid mixed solution into the centrifuge to separate the first filtrate and wet sodium fluorosilicate solid. Then the wet sodium fluorosilicate solid is washed and dried to obtain a sodium fluorosilicate dry pro...

Embodiment 3

[0108] Embodiment 3: For the annual production of 5GW crystalline silicon solar cell project, the amount of waste acid solution produced by acid etching silicon wafers is 50m 3 / d, the waste acid solution contains 10% fluosilicic acid, 13% hydrofluoric acid, 40% nitric acid and 0.7% hydrochloric acid. This implementation case includes the following steps:

[0109] The steps for preparing sodium fluorosilicate solid: first put the waste acid solution into the first-stage crystallization tank, start the stirrer, stir at 180rpm, and then add 290kg / m 3 Pass the saturated sodium chloride solution into the crystallization tank at a constant speed, keep the reaction temperature at 10°C, and continue to stir for 120 minutes to react. After the reaction, pass the solid-liquid mixed solution into the centrifuge to separate the first filtrate and wet sodium fluorosilicate solid , and then wash and dry the wet sodium fluorosilicate solid to obtain a sodium fluorosilicate dry product, the...

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Abstract

The invention provides an acid etching silicon wafer waste acid liquid treatment method and system. The treatment method comprises the following steps: adding a sodium salt solution into an acid etching silicon wafer waste acid liquid, performing continuous stirring for 30-180 min to form a first solid-liquid mixture, and performing centrifugation to obtain a sodium fluorosilicate solid and a first filtrate; adding a sodium hydroxide solution into the first filtrate, controlling the pH to be 2-4, performing continuous stirring for 20-60 min to form a second solid-liquid mixture, and performingcentrifugation to obtain a sodium hydrogen difluoride solid and a second filtrate; adding a calcium chloride solution to the second filtrate, adjusting the pH to be 2-4, performing continuous stirring for 20-60 min to form a third solid-liquid mixture, and performing centrifugation to obtain a calcium fluoride solid and a third filtrate; and adding lime milk to the third filtrate, adjusting the pH to be 8-9, separating a precipitate and a fourth filtrate, recovering the fourth filtrate, and treating the precipitate as a solid waste. The provided scheme realizes the resource utilization of thewaste acid liquid.

Description

technical field [0001] The invention relates to the technical field of waste liquid treatment, in particular to a method and system for treating waste acid liquid for acid etching silicon wafers. Background technique [0002] At present, monocrystalline silicon or polycrystalline silicon is an ideal material for manufacturing integrated circuits and photovoltaic solar cells. In the existing process of preparing monocrystalline silicon or polycrystalline silicon, in addition to using chemical etching to remove impurities on the silicon surface, it also needs to be chemically cleaned with high-concentration nitric acid and hydrofluoric acid, and the cleaned acid etches the silicon wafer. The waste acid liquid contains nitric acid, hydrofluoric acid, fluosilicic acid and other acid liquids. It is conceivable that this acid-etched silicon wafer waste acid solution is highly acidic and corrosive, and if it is discharged without treatment, it will bring immeasurable environmental...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F11/22
CPCC01F11/22
Inventor 杨招艺虞红波徐俊王坤琴
Owner 北京环球中科水务科技股份有限公司
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