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Collecting and recycling method of polycrystalline silicon texturing etching waste liquid

A technology for etching waste liquid and treatment methods, which is applied in the direction of nitrogen oxides/oxyacids, nitric acid, etc., can solve the problems of low concentration of hydrofluoric acid and nitric acid, failure to use normally, and increase the burden on enterprises, so as to save costs, The effect of protecting the environment

Inactive Publication Date: 2015-10-14
SUZHOU KZONE EQUIP TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For example, the Chinese invention patent whose publication number is CN102409343A discloses the method of using diffusion dialysis to reclaim hydrofluoric acid and nitric acid in waste acid, and realize the separation of fluosilicic acid at the same time; the disadvantage of this method is the concentration of hydrofluoric acid and nitric acid recovered It is too low to be used normally. At the same time, new acidic waste liquid will be generated while separating the fluorosilicic acid complex, which will increase the burden on the enterprise

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] This embodiment provides a treatment method for reclaiming and regenerating polysilicon texturing waste etching solution, which includes the following steps:

[0019] (a) Add sodium hydroxide to the etching waste liquid under stirring conditions at 0°C, so that the molar ratio of fluorosilicate ion to sodium element in the added sodium compound is 1:1, and react until no precipitation occurs, Filter to obtain the first precipitate and the first filtrate;

[0020] (b) Add calcium hydroxide to the first filtrate under stirring conditions at 0°C, so that the molar ratio of fluoride ions in the first filtrate to calcium elements in the added calcium hydroxide is 1.8:1, and react until no precipitation occurs , filtered to obtain the second precipitate and the second filtrate;

[0021] (c) Distilling the second filtrate at a vacuum degree of 380 mmHg and 40° C. to obtain a nitric acid solution.

Embodiment 2

[0023] This embodiment provides a treatment method for reclaiming and regenerating polysilicon texturing waste etching solution, which includes the following steps:

[0024] (a) Add a mixture of sodium oxide and sodium hydroxide to the etching waste liquid under stirring conditions at 40°C, so that the molar ratio of fluorosilicate ion to sodium element in the added sodium compound is 1:4, and react To no longer produce precipitation, filter to obtain the first precipitation and the first filtrate;

[0025] (b) Add magnesium hydroxide to the first filtrate under stirring conditions at 40°C, so that the molar ratio of fluoride ions in the first filtrate to magnesium elements in the added magnesium hydroxide is 3:1, and react until no precipitation occurs , filtered to obtain the second precipitate and the second filtrate;

[0026] (c) Distilling the second filtrate at a vacuum degree of 760 mmHg and 120° C. to obtain a nitric acid solution.

Embodiment 3

[0028] This embodiment provides a treatment method for reclaiming and regenerating polysilicon texturing waste etching solution, which includes the following steps:

[0029] (a) Add a mixture of sodium oxide and sodium hydroxide to the etching waste liquid under stirring conditions at 20°C, so that the molar ratio of fluorosilicate ion to sodium element in the added sodium compound is 1:2, and react To no longer produce precipitation, filter to obtain the first precipitation and the first filtrate;

[0030] (b) Add barium hydroxide to the first filtrate under stirring conditions at 20°C, so that the molar ratio of fluoride ions in the first filtrate to the barium element in the added barium hydroxide is 2:1, and react until no precipitation occurs , filtered to obtain the second precipitate and the second filtrate;

[0031] (c) Distilling the second filtrate at a vacuum degree of 500 mmHg and 60° C. to obtain a nitric acid solution.

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Abstract

The invention relates to a collecting and recycling method of polycrystalline silicon texturing etching waste liquid. The collecting and recycling method comprises following steps: (a) under stirring conditions, an alkali metal compound is added into an etching waste liquid for reaction until no more precipitate is generated, and a first precipitate and a first filtrate are obtained via filtering; (b) under stirring conditions, an alkaline earth metal compound is added into the first filtrate for reaction until no more precipitate is generated, and a second precipitate and a second filtrate are obtained via filtering; and (c) the second filtrate is subjected to distillation so as to obtain a nitric acid solution. According to the collecting and recycling method of polycrystalline silicon texturing etching waste liquid, the alkali metal compound is added into the etching waste liquid for reaction until no more precipitate is generated, the alkaline earth metal compound is added into the filtrate after filtering, and then filtration is carried out for a second time so as to obtain the nitric acid solution via distillation, so that fluosilicate ions and fluorine ions in the waste liquid are removed, a fluosilicate, a fluoride salt, and the reusable nitric acid solution are obtained; environment protection is realized; and cost is reduced.

Description

technical field [0001] The invention belongs to the field of sewage treatment, and relates to a treatment method for etching waste liquid, in particular to a treatment method for recovering and regenerating etching waste liquid from polysilicon texturing. Background technique [0002] With the vigorous development of the solar cell industry, the amount of etching liquid used to etch silicon and silicon compounds in its production process is also increasing, so the amount of etching waste liquid is also increasing; The etching solution is prepared from a certain concentration of nitric acid and hydrofluoric acid. The formation and accumulation of fluosilicic acid during the etching process is the main reason for the reduction of the etching ability of the etching solution and the inability to continue to use it. Therefore, it is of great economic and social value to develop a treatment method for recycling and regenerating the etching waste liquid. [0003] At present, ther...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B21/38
Inventor 蒋新朱信俊施利君柳小平
Owner SUZHOU KZONE EQUIP TECH