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Method for preparing ammonium bifluoride by utilizing BOE waste liquid

A technology of ammonium bifluoride and anhydrous hydrogen fluoride, which is applied in the direction of ammonium fluoride and ammonium halide, can solve the problems of high equipment requirements, large investment costs, high production costs, etc., and achieve the goal of reducing production costs, avoiding environmental pollution, and mild process conditions Effect

Pending Publication Date: 2021-01-01
江苏电科环保有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problems that the existing ammonium bifluoride preparation method requires high equipment, high investment cost, high water content, easy agglomeration, difficult storage, and high production cost, the present invention provides a method for preparing hydrogen fluoride using BOE waste liquid The ammonium method, through the recycling of BOE waste liquid, not only can avoid the direct discharge of BOE waste liquid to cause environmental pollution, but also the ammonium bifluoride product prepared by recycling has high purity, low water content, low investment cost and low production cost

Method used

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  • Method for preparing ammonium bifluoride by utilizing BOE waste liquid
  • Method for preparing ammonium bifluoride by utilizing BOE waste liquid
  • Method for preparing ammonium bifluoride by utilizing BOE waste liquid

Examples

Experimental program
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Effect test

Embodiment 1

[0023] Add 4.56kg of barium hydroxide to 1 ton of BOE waste liquid containing 0.1% ammonium fluorosilicate, 0.3% ammonium sulfate, 15% ammonium fluoride and 6% ammonium bifluoride in mass fraction, and the addition amount of barium hydroxide is theoretical 94% of the value, stirred for 30 minutes, and after filtration, separated and removed barium sulfate and barium hexafluorosilicate precipitated filter residue to obtain a filtrate containing ammonium fluoride and ammonium bifluoride.

[0024] The filtrate was placed in a water-cooled reactor, fed with anhydrous hydrogen fluoride, mixed uniformly and fully reacted at 30°C until the pH of the mixed solution reached 4, and then stopped feeding anhydrous hydrogen fluoride to obtain an ammonium bifluoride solution.

[0025] Evaporate the ammonium bifluoride solution under reduced pressure in the three-effect evaporator, the evaporation time is 30min, the temperature is 70°C, and the pressure is -0.03Mpa to obtain the ammonium bifl...

Embodiment 2

[0028] Add 55.81 kg of barium hydroxide to 1 ton of BOE waste liquid containing 2% ammonium fluorosilicate, 3% ammonium sulfate, 21% ammonium fluoride and 12% ammonium bifluoride in mass fraction, and the addition amount of barium hydroxide is theoretical 96% of the value, stirred for 40 minutes, and after filtration, separated and removed barium sulfate and barium hexafluorosilicate precipitated filter residue to obtain a filtrate containing ammonium fluoride and ammonium bifluoride.

[0029] The filtrate was placed in a water-cooled reactor, fed with anhydrous hydrogen fluoride, mixed uniformly and fully reacted at 50°C until the pH of the mixed solution reached 5, then stopped feeding anhydrous hydrogen fluoride to obtain an ammonium bifluoride solution.

[0030] Evaporate the ammonium bifluoride solution under reduced pressure in the three-effect evaporator, the evaporation time is 50min, the temperature is 90°C, and the pressure is -0.05Mpa to obtain the ammonium bifluorid...

Embodiment 3

[0033] Add 97.96kg of barium hydroxide to 1 ton of BOE waste liquid containing 5% ammonium fluorosilicate, 4% ammonium sulfate, 25% ammonium fluoride and 15% ammonium bifluoride in mass fraction, and the addition amount of barium hydroxide is theoretical 99% of the value, stirred for 60 minutes, and after filtration, the precipitated filter residue of barium sulfate and barium hexafluorosilicate was separated and removed to obtain a filtrate containing ammonium fluoride and ammonium bifluoride.

[0034] The filtrate was placed in a water-cooled reactor, fed with anhydrous hydrogen fluoride, mixed uniformly and fully reacted at 60°C until the pH of the mixed solution reached 4.5, then stopped feeding anhydrous hydrogen fluoride to obtain ammonium bifluoride solution.

[0035] Evaporate the ammonium bifluoride solution under reduced pressure in the three-effect evaporator, the evaporation time is 60min, the temperature is 120°C, and the pressure is -0.06Mpa to obtain the ammonium...

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Abstract

The invention provides a method for preparing ammonium bifluoride from BOE waste liquid, which can avoid environmental pollution caused by directly discharging the BOE waste liquid by recycling the BOE waste liquid, and the recovered and prepared ammonium bifluoride product has the advantages of high purity, low water content, low investment cost and low production cost. According to the method, BOE waste liquid generated by a semiconductor etching process is used as a raw material, barium hydroxide is used as a precipitator to remove impurities in the waste liquid, then anhydrous hydrogen fluoride is introduced to convert ammonium fluoride into ammonium hydrogen fluoride, and then evaporation, cooling crystallization, centrifugal separation and drying are performed to obtain high-purity ammonium hydrogen fluoride with low water content.

Description

technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to the technical field of BOE waste liquid treatment, in particular to a method for preparing ammonium bifluoride by using BOE waste liquid. Background technique [0002] BOE buffer etching solution is hydrofluoric acid (HF) and ammonium fluoride (NH 4 F) Mixed according to different proportions, HF is the main etching solution, NH 4 F is used as a buffer. After the semiconductor element etching process, the main component of the BOE waste liquid is ammonium fluoride (NH 4 F) and ammonium bifluoride (NH 4 HF 2 ), and contain a small amount of fluorosilicate ions and sulfate ions; if discharged directly, the ammonia nitrogen and fluorine ions will have a serious impact on the environment. Aquatic ecosystems, and excessive fluoride ions will cause great harm to drinking water, crops and human health. [0003] Ammonium bifluoride is a white or colorless transparent or...

Claims

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Application Information

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IPC IPC(8): C01C1/16
CPCC01C1/162C01P2006/80
Inventor 郭维林刘晓雨李张成刘围
Owner 江苏电科环保有限公司
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