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Governing method for discharging fluorine-containing gas amorphously in aluminum electrolysis production process

A technology for unorganized emission and fluorine-containing gas, which is applied in the direction of gas treatment, separation methods, chemical instruments and methods, etc., can solve the problems of complex recovery process and low concentration of NaF in the absorption liquid, and achieve high defluorination efficiency and low energy consumption , the effect of convenient operation

Active Publication Date: 2018-05-04
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Alkaline method is absorbed by sodium hydroxide or sodium bicarbonate solution, HF is converted to NaF, while SO 2 converted to Na 2 SO 3 , the pH value is controlled between 6.0 and 7.0, which can reduce the corrosion effect on the equipment, but the concentration of NaF in the absorption liquid is low, and the subsequent recovery process is complicated

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Set multi-layer staggered nozzles at the discharge skylight of the aluminum electrolysis plant to form a spray system; spray alkaline sodium metaaluminate solution through the nozzles (spray intensity 13-25m 3 / (m 2 h)), the alkaline sodium metaaluminate solution absorbs fugitive discharge of fluorine-containing gas to form an absorption solution containing cryolite;

[0024] The concentration of HF in fugitive emissions of fluorine-containing gases is 0.5mg / Nm 3 , under the action of the induced draft fan, through the leaching system; the gaseous hydrogen fluoride in the unorganized discharge of fluorine-containing gas reacts with alkaline sodium metaaluminate to form cryolite;

[0025] Na in the alkaline sodium metaaluminate solution 2 O concentration is 25.8g / L, Al 2 o 3 The concentration is 25.2g / L;

[0026] The basis for the spray amount of the alkaline sodium metaaluminate solution is: control the cryolite in the absorbed liquid to account for 1% of the total...

Embodiment 2

[0034] Method is with embodiment 1, and difference is:

[0035] (1) The concentration of HF in fugitive emissions of fluorine-containing gases is 1.0mg / Nm 3 ;

[0036] (2) Na in alkaline sodium metaaluminate solution 2 O concentration is 35.8g / L, Al 2 o 3 The concentration is 30.5g / L;

[0037] (3) The amount of spraying accounts for 3% of the total weight of the absorption liquid by cryolite in the absorption liquid;

[0038] (4) Add sodium metaaluminate to the filtrate obtained after filtration to adjust to Na 2 O concentration is 35.8g / L, Al 2 o 3 The concentration is 30.5g / L;

[0039] (5) cryolite molecular ratio is 2.1, and the weight content of impurity is 1.6%;

[0040] (6) When the carbon alkali concentration of the alkaline sodium metaaluminate solution for recycling is accumulated to 30g / L, the caustic treatment to the concentration of carbon alkali is 3g / L;

[0041] (7) After the scrubbing gas is demistered, the smoke droplet content is 75mg / Nm 3 ;

[004...

Embodiment 3

[0044]Method is with embodiment 1, and difference is:

[0045] (1) The concentration of HF in fugitive emissions of fluorine-containing gases is 1.5mg / Nm 3 ;

[0046] (2) Na in alkaline sodium metaaluminate solution 2 O concentration is 15.8g / L, Al 2 o 3 The concentration is 10.5g / L;

[0047] (3) The amount of spraying accounts for 2% of the total weight of the absorption liquid by cryolite in the absorption liquid;

[0048] (4) Add sodium metaaluminate to the filtrate obtained after filtration to adjust to Na 2 O concentration is 15.8g / L, Al 2 o 3 The concentration is 10.5g / L;

[0049] (5) cryolite molecular ratio is 2.5, and the weight content of impurity is 1.8%;

[0050] (6) When the carbon alkali concentration of the alkaline sodium metaaluminate solution for recycling is accumulated to 60g / L, the caustic treatment is carried out until the concentration of carbon alkali is 10g / L;

[0051] (7) After the scrubbing gas is demistered, the smoke droplet content is 68...

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Abstract

The invention relates to a governing method for discharging fluorine-containing gas amorphously in an aluminum electrolysis production process. The method comprises the following steps: (1) arrangingmultiple layers of nozzles which are arranged in a staggered manner at a discharge skylight of an aluminum electrolysis plant and spraying an alkaline sodium metaaluminate solution through the nozzles, wherein the alkaline sodium metaaluminate solution absorbs an absorption liquid containing cryolite after the fluorine-containing is discharged amorphously, and gaseous hydrogen fluoride and alkaline sodium metaaluminate react to generate cryolite; (2) collecting and filtering the absorption liquid containing cryolite, wherein the solid phase is cryolite; and adding sodium metaaluminate into thefiltrate for circular use; and (3) demisting the washed gas and discharging the gas into atmosphere. The method provided by the invention has the advantages of being simple in process, convenient tooperate, small in energy consumption, good in pollutant removal effect and the like.

Description

technical field [0001] The invention belongs to the technical field of industrial waste gas treatment, and in particular relates to a treatment method for unorganized discharge of fluorine-containing gas in the aluminum electrolysis production process. Background technique [0002] During the aluminum electrolysis process, the air pollutants released mainly include fluorides (HF, CF 4 、C 2 f 6 etc.), SO 2 and gas particles, among which fluoride is the most harmful. According to the characteristics of the current electrolysis process, the airtight cover of any kind of electrolytic cell cannot be completely closed. During the process of anode replacement and aluminum extraction, some gas will always be emitted into the workshop and discharged into the atmosphere through the skylight of the workshop, which is called non-organization. Organize the emission of fluorine-containing gases. As far as the amount of fluoride in the smoke is concerned, the amount of fugitive emissio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/78B01D53/68C01F7/54
CPCB01D53/68B01D53/78B01D2252/10B01D2257/2047C01F7/54
Inventor 张廷安刘燕张伟光曹雪娇豆志河吕国志
Owner NORTHEASTERN UNIV
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