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Method for recycling mixed acid of nitric acid, hydrofluoric acid and acetic acid

A technology of hydrofluoric acid and mixed acid, applied in the preparation of calcium/strontium/barium nitrate, carboxylate, calcium/strontium/barium fluoride, etc., can solve the problems of large amount of mixed acid, difficult filtration, and narrow application range. , to achieve the effect of low investment cost and operating cost, significant economic benefit and wide application range

Inactive Publication Date: 2020-05-08
3R ENVIRONMENTAL TECH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the photovoltaic industry, in addition to the above-mentioned mixed acids, the mixed acids of nitric acid, hydrofluoric acid and acetic acid are also produced in a huge amount. The addition of acetic acid makes the treatment of mixed acids more difficult. At present, there is no resource recovery of mixed acids containing acetic acid, hydrofluoric acid and nitric acid. processing technology
[0005] Patent application CN201811219056 - A zero-discharge and resource utilization method for photovoltaic pickling waste liquid. The calcium fluoride and calcium carbonate mud produced by the process described in the process are of low quality, narrow scope of application, low added value of the product, and insignificant economic benefits
In addition, the calcium fluoride produced by the process directly neutralized by lime is slow in precipitation and difficult to filter, resulting in low industrial production efficiency

Method used

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  • Method for recycling mixed acid of nitric acid, hydrofluoric acid and acetic acid
  • Method for recycling mixed acid of nitric acid, hydrofluoric acid and acetic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] Adopt the inventive method to jointly process the fluorine-containing mixed acid that certain stainless steel enterprise and certain photovoltaic enterprise produce, wherein the mixed acid of stainless steel enterprise contains acidity (in terms of HNO 3 Total) mass fraction 2.94%, fluoride ion mass fraction 0.87%, iron ion mass fraction 2.61%, chromium ion mass fraction 0.34%; the mixed acid HNO of photovoltaic enterprises 3 The mass fraction is 15.12%, the HF mass fraction is 8.2%, and the HAc mass fraction is 7.87%. According to the inventive method, the processing steps are as follows:

[0051] S010, stainless steel fluorine-containing mixed acid in 1# neutralization sedimentation tank, adjust pH = 1 with lime, and mechanically stir to precipitate Fe 3+

[0052] After the reaction is completed, it is pumped to the 1# plate and frame filter press to separate the iron sludge through the filter press, and the filtered filtrate is sent to the 2# neutralization sedimen...

Embodiment 2

[0066] Adopt the inventive method to jointly process the fluorine-containing mixed acid that certain stainless steel enterprise and certain photovoltaic enterprise produce, the mixed acid of its stainless steel enterprise contains acidity (in terms of HNO 3 Total) 2.94%, fluoride ion 0.87%, iron ion 2.61%, chromium ion 0.34%; the mixed acid HNO of photovoltaic enterprises 3 The mass fraction is 15.12%, the HF mass fraction is 8.2%, and the HAc mass fraction is 7.87%. According to the inventive method, the processing steps are as follows:

[0067] S010, stainless steel fluorine-containing mixed acid in 1# neutralization sedimentation tank, adjust pH=2 with lime, mechanically stir to precipitate Fe 3+

[0068] After the reaction is completed, it is pumped to the 1# plate and frame filter press to separate the iron sludge through the filter press, and the filtered filtrate is sent to the 2# neutralization sedimentation tank.

[0069] S012, after the filtrate of 1# plate and fr...

Embodiment 3

[0082] Adopt the inventive method to jointly process the fluorine-containing mixed acid that certain stainless steel enterprise and certain photovoltaic enterprise produce, the mixed acid of its stainless steel enterprise contains acidity (in terms of HNO 3 Total) 2.94%, fluoride ion 0.87%, iron ion 2.61%, chromium ion 0.34%; the mixed acid HNO of photovoltaic enterprises 3 The mass fraction is 15.12%, the HF mass fraction is 8.2%, and the HAc mass fraction is 7.87%. According to the inventive method, the processing steps are as follows:

[0083] S010, stainless steel fluorine-containing mixed acid in 1# neutralization sedimentation tank, adjust pH=3 with lime, and mechanically stir to precipitate Fe 3+

[0084] After the reaction is completed, it is pumped to the 1# plate and frame filter press to separate the iron sludge through the filter press, and the filtered filtrate is sent to the 2# neutralization sedimentation tank.

[0085] S012, after the filtrate of 1# plate an...

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Abstract

The invention provides a method for recycling mixed acid of nitric acid, hydrofluoric acid and acetic acid. The method is briefly described in the specification: 1) lime is added into mixed acid in the stainless steel industry, and iron mud and heavy metal mud such as chromium, nickel, zinc and the like are precipitated respectively by adjusting to different pH values; 2) the obtained dilute calcium nitrate solution enters an evaporation platform to obtain liquid calcium nitrate with the content of more than 50%; 3) the liquid calcium nitrate is reacted with mixed acid in the photovoltaic industry to generate calcium fluoride precipitate; 4) separation then is carried out to obtain a high-purity CaF2 product and lime is added into the filtrate to neutralize and precipitate to remove residual fluorine ions and silicate radicals; 5) industrial nitric acid then is added into the separated filtrate for converting calcium acetate in the solution into calcium nitrate and acetic acid, and then the acetic acid and water are evaporated out through an evaporation platform to obtain a calcium nitrate concentrated solution and dilute acetic acid; 6) finally, the calcium nitrate concentrated solution is cooled, crystallized and centrifugally separated to obtain a Ca(NO3)2.4H2O product with the mass fraction of more than 90%. According to the method, the limitation of an existing fluorine-containing mixed acid treatment process is solved, and the purpose of higher resource recycling value is achieved.

Description

technical field [0001] The invention relates to the technical field of resource recycling and reuse of fluorine-containing mixed acids, and in particular provides a method for joint treatment, recycling and reuse of nitric acid, hydrofluoric acid, and acetic acid mixed acids produced in the stainless steel industry and the photovoltaic industry. Background technique [0002] Photovoltaic power generation uses polycrystalline silicon cells, and in the production process of cell components, it is necessary to use hydrofluoric acid mixed acid to clean silicon wafers. According to statistics, at present, more than 450,000 tons of such fluorine-containing waste acid are produced in the country every year, and this fluorine-containing waste acid contains 8% to 12% hydrogen fluoride and 18% to 25% nitric acid. More accurate control of corrosion depth and corrosion width. HNO 3 - The corrosion of silicon by HF etching solution is easy to carry out. For silicon wafer devices that r...

Claims

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Application Information

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IPC IPC(8): C01F11/22C01F11/36C07C51/02C07C53/08
CPCC01F11/22C01F11/36C07C53/08C07C51/02
Inventor 邓炳林丁德才樊文星陈建龙龙国兵
Owner 3R ENVIRONMENTAL TECH CO LTD
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