Method for recycling fluorine-containing waste liquid

A technology of waste liquid and fluorosilicic acid, which is applied in the directions of hydrogen fluoride, fluorine/hydrogen fluoride, nitrogen oxides/oxyacids, etc., can solve the problem of no recycling of fluorine resources, and achieves low cost, simple treatment method and high recovery efficiency. Effect

Pending Publication Date: 2020-12-04
衢州市鼎盛化工科技有限公司
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Problems solved by technology

[0004] The present invention proposes a method for recycling fluorine-containing waste liquid, which solves the prob

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  • Method for recycling fluorine-containing waste liquid

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Embodiment 1

[0028] A method for recycling fluorine-containing waste liquid, comprising:

[0029] Add 1000kg of fluorine-containing waste acid into the stirred reactor, and simultaneously open condenser A (control cooling temperature 30°C) and condenser C (control cooling temperature -5°C); slowly and uniformly add 1450kg of 95% concentrated Sulfuric acid was added while stirring, and the temperature of the reaction kettle was displayed as 120°C. Hydrogen fluoride, silicon tetrafluoride, and nitric acid vapor escape in the form of gas; the output of condenser A is 436.2 kg of nitric acid, and the output of condenser C is 103.1 kg of hydrofluoric acid. Silicon tetrafluoride is absorbed with water to become concentrated fluorosilicic acid and silicon dioxide. After the silicon dioxide is separated, the remaining concentrated fluorosilicic acid is mixed with fluorine-containing waste liquid and continues to enter the system for treatment.

[0030] The above used concentrated sulfuric acid be...

Embodiment 2

[0033] A method for recycling fluorine-containing waste liquid, comprising:

[0034] Add 1000kg of fluorine-containing waste acid into the stirred reactor, and simultaneously open condenser A (control cooling temperature 30°C) and condenser C (control cooling temperature -5°C); slowly and uniformly add 1250kg of 95% concentrated Sulfuric acid was added while stirring, and the temperature of the reaction kettle was displayed as 112°C. Hydrogen fluoride, silicon tetrafluoride, and nitric acid vapor escape in the form of gas; the output of condenser A is 425.1 kg of nitric acid, and the output of condenser C is 102.9 kg of hydrofluoric acid. Silicon tetrafluoride is absorbed with water to become concentrated fluorosilicic acid and silicon dioxide. After the silicon dioxide is separated, the remaining concentrated fluorosilicic acid is mixed with fluorine-containing waste liquid and continues to enter the system for treatment.

[0035] The above used concentrated sulfuric acid be...

Embodiment 3

[0038] A method for recycling fluorine-containing waste liquid, comprising:

[0039] Add 1000kg of fluorine-containing waste acid to the stirred reactor, and simultaneously open condenser A (control the cooling temperature at 30°C) and condenser C (control the cooling temperature at -5°C); slowly and uniformly add 1100kg of 95% concentrated Sulfuric acid was added while stirring, and the temperature of the reaction kettle was displayed as 105°C. Hydrogen fluoride, silicon tetrafluoride, and nitric acid vapor escape in the form of gas; the output of condenser A is 419.6 kg of nitric acid, and the output of condenser C is 102.8 kg of hydrofluoric acid. Silicon tetrafluoride is absorbed with water to become concentrated fluorosilicic acid and silicon dioxide. After the silicon dioxide is separated, the remaining concentrated fluorosilicic acid is mixed with fluorine-containing waste liquid and continues to enter the system for treatment.

[0040] The above used concentrated sulf...

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Abstract

The invention provides a method for recycling fluorine-containing waste liquid, which comprises the following steps: under the action of concentrated sulfuric acid, hydrogen fluoride, silicon tetrafluoride and nitric acid steam escape in a gaseous state from the fluorine-containing waste liquid, and then are subjected to two-stage condensation; and nitric acid is obtained from first-stage condensation, and hydrofluoric acid is obtained from second-stage condensation. Silicon tetrafluoride gas is treated to obtain concentrated fluosilicic acid and silicon dioxide; and after silicon dioxide is separated, the concentrated fluosilicic acid and the fluorine-containing waste liquid are mixed and circulated in a system, wherein the fluorine-containing waste liquid comprises hydrofluoric acid, nitric acid and fluosilicic acid. The treatment method is simple, low in cost, high in recovery efficiency and suitable for industrial popularization and application. By using the treatment method provided by the invention, the recovery rate of hydrofluoric acid or nitric acid contained in the original fluorine-containing waste liquid is relatively high. The recovery concentration of nitric acid in the photovoltaic industry is greater than or equal to 65%, and the recovery concentration of hydrofluoric acid is greater than or equal to 95%; and the nitric acid recovery concentration in the electronic industry is larger than or equal to 45%, and hydrofluoric acid recovery concentration is larger than or equal to 20%.

Description

technical field [0001] The invention relates to the technical field of waste acid treatment, in particular to a method for recycling fluorine-containing waste liquid. Background technique [0002] Electronic factories and photovoltaic panel manufacturers, in order to ensure the integrity, precision and yield of advanced manufacturing processes, use electronic grade hydrofluoric acid and nitric acid to treat silicon wafers during the production process, resulting in a large amount of fluorine-containing waste acid. The hydrofluoric acid content of these fluorine-containing waste acids is generally 4-10%, the nitric acid content is generally 5-30%, and the fluosilicic acid content is generally 0.6-6%. The EIA reports of most of these factories list fluorine-containing waste acid as a hazardous waste, and a few factories list fluorine-containing waste acid as a by-product. According to China's current laws, hazardous waste requires specialized treatment by qualified units, or ...

Claims

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Application Information

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IPC IPC(8): C01B21/46C01B7/19C01B33/12
CPCC01B7/193C01B7/195C01B21/46C01B33/12
Inventor 应盛荣姜战闻涛周贞峰应悦
Owner 衢州市鼎盛化工科技有限公司
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