CN111097277A - Waste nitric acid treatment method - Google Patents
Waste nitric acid treatment method Download PDFInfo
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- CN111097277A CN111097277A CN202010036164.5A CN202010036164A CN111097277A CN 111097277 A CN111097277 A CN 111097277A CN 202010036164 A CN202010036164 A CN 202010036164A CN 111097277 A CN111097277 A CN 111097277A
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- nitric acid
- waste nitric
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/30—Alkali metal compounds
- B01D2251/304—Alkali metal compounds of sodium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/604—Hydroxides
Abstract
The invention discloses a waste nitric acid treatment method, which comprises the steps of heating a waste nitric acid solution to a certain temperature, adding a ferrous solution into the waste nitric acid solution, stirring, leading tail gas released by reaction to pass through a clear water absorption tower, and then a mixed reducing agent absorption tower of sodium sulfide, sodium sulfite and sodium hydroxide with the mass ratio of 2:1:1, absorbing nitrogen oxides, and then discharging. According to the invention, the mixed reducing agent of sodium sulfide, sodium sulfite and sodium hydroxide with the mass ratio of 2:1:1 is used for treating the tail gas nitric oxide generated by nitric acid, so that the problems of low treatment efficiency of nitric oxide gas, serious standard exceeding of the nitric oxide, standard discharge of the nitric oxide generated during nitric acid treatment and the like are solved, and low-cost and large-scale clean production of nitric acid treatment is realized.
Description
Technical Field
The invention relates to the technical field of waste acid recovery treatment, in particular to a method for treating waste nitric acid.
Background
At present, manufacturers for producing stainless steel at home and abroad mostly adopt nitric acid-hydrofluoric acid mixed pickling to remove oxides. The mixed acid of nitric acid and hydrofluoric acid is adopted for pickling, so that the pickling speed is high, the pickling is not easy to be carried out, and the pickled steel keeps a good surface. The three are not achieved by other acid washing. After multiple times of pickling, the metal ions in the pickling solution increase to a certain concentration, and the acid content is reduced to a certain percentage, namely the pickling capacity is lost to form waste liquid, but the total acidity in the waste liquid is still quite high, and the waste liquid contains a large amount of metal salts such as iron, nickel, chromium and the like. Nitric acid and hydrofluoric acid are highly corrosive agents, chromium is a highly toxic substance, and the waste liquid must be properly treated. The mixed acid of nitric acid and sulfuric acid (30% of which is commonly used in industry to react with benzene to produce nitrobenzene, and then hydrogenated to produce aniline, which is an intermediate for synthesizing dye, medicine and pesticide. the production of oxalic acid takes the crop wastes such as corn pistil, bagasse, rice husk and peanut shell as raw materials to react with nitric acid to produce oxalic acid, and the reaction of nitric acid with propylene or ethylene and glycol can also produce oxalic acid, the nitric acid in the military industry is used for producing TNT explosive, and also used for refining and extracting nuclear raw material, plutonium is an important nuclear fuel in the refining process, the synthetic perfume nitric acid reacts with xylene to produce musk xylene smell, which is widely used for preparing cosmetics, soaps and indoor perfumes.
Many researches are carried out on the treatment of nitric acid mixed acid waste liquid in countries such as Europe, America, and Reid, and chemical methods, evaporation methods, ion exchange methods, solvent extraction methods, biological methods and the like are generally adopted. The chemical method can recover some useful substances, but the method is complicated and has more equipment, the ion exchange method is an improvement by changing a fixed bed into a fluidized bed, but the ion exchange method also has the advantages of low energy consumption, easy selection of equipment and materials and low acid recovery rate due to the simultaneous extraction of waste acid concentration and dilute acid treatment problems. The reduced pressure evaporation method makes it possible to select temperature-resistant and corrosion-resistant material, and has high acid recovering rate. The U.S. employs a double evaporation process, but this produces large amounts of low acid wastewater. These factors all result in high cost and difficult operation of nitric acid mixed acid treatment, which is not favorable for realizing industrial production.
Disclosure of Invention
The invention aims to provide a high-efficiency treatment method for tail gas generated in the process of treating waste nitric acid.
In order to solve the technical problems, the invention adopts the technical scheme that:
a method for treating waste nitric acid comprises the steps of heating a waste nitric acid solution to a certain temperature, adding a ferrous solution into the waste nitric acid solution, stirring, enabling tail gas released by reaction to pass through a clear water absorption tower, adding water into sodium sulfide, sodium sulfite and sodium hydroxide according to the mass ratio of 2:1:1 to prepare a mixed reducing agent solution absorption tower with the effective content of 40%, and discharging after absorption treatment of nitrogen oxides.
Preferably, the heating temperature of the waste nitric acid solution is 75-85 ℃.
Preferably, after the stirring step, the method further comprises monitoring the content of ferrous ions in the solution for judging the reaction end point, wherein the content of ferrous ions at the reaction end point is 0.2%.
Preferably, the tail gas continuously passes through two mixed reducing agent absorption towers of sodium sulfide, sodium sulfite and sodium hydroxide with the mass ratio of 2:1: 1; the mixed reducing agent comprises a mixed reducing agent solution with the effective content of 40% prepared by adding sodium sulfide, sodium sulfite and sodium hydroxide according to the mass ratio of 2:1: 1.
Preferably, the method comprises adding a liquid alkali to the mixed reducing agent solution to maintain the pH of the mixed reducing agent; the pH was maintained at 13.
Preferably, the method further comprises detecting the emitted tail gas.
Preferably, the ORP value of the effective component of the mixed reducing agent is more than-600 mV.
In summary, the technical scheme of the invention has the following beneficial effects: according to the invention, sodium sulfide, sodium sulfite and sodium hydroxide in a mass ratio of 2:1:1 are added with water to prepare a mixed reducing agent solution with an effective content of 40% to treat tail gas nitric oxide generated by nitric acid, so that the problems of low treatment efficiency of nitric oxide gas, serious standard exceeding of nitric oxide, standard emission of nitric oxide generated during nitric acid treatment and the like are solved, and low-cost large-scale clean production of nitric acid treatment is realized.
Drawings
FIG. 1 is a flow chart of a method for treating waste nitric acid according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, but the technical solutions do not limit the scope of the present invention.
Referring to fig. 1, the invention relates to a treatment method of waste nitric acid, which is a treatment process developed by using sodium sulfide, sodium sulfite and sodium hydroxide in a mass ratio of 2:1:1 and adding water to prepare a mixed reducing agent solution with an effective content of 40% to treat nitrogen oxide in tail gas generated by nitric acid, solves the problems of low treatment efficiency of nitrogen oxide gas, serious standard exceeding of nitrogen oxide, standard emission of nitrogen oxide generated during nitric acid treatment and the like, and realizes low-cost and large-scale clean production of nitric acid treatment. The reaction formula is as follows:
Fe2++2H++NO-(concentrated) ═ Fe3++H2O+NO2↑
3Fe2++4H++NO-(rare) ═ 3Fe3++2H2O+NO↑
NO+NO2+ mixed reduction treatment agent- → N2+H2O
The waste nitric acid is easily decomposed to generate nitrogen oxides through the working procedures of heating, stirring, reacting with ferrous ions and the like, and the direct discharge can cause air pollution, so that the mixed reducing agent solution with the effective content of 40% is prepared by adding water into sodium sulfide, sodium sulfite and sodium hydroxide with the mass ratio of 2:1:1, and is used for treating tail gas nitrogen oxides generated by nitric acid. In the process of treating nitrogen oxides by using the mixed reducing agent, liquid alkali is added to ensure that the pH value (maintained at about 13) of the absorbent and the effective component (ORP value) of the absorbent are within a certain range (above 600 mV), so that the nitrogen oxides can be efficiently absorbed and reacted, converted into nitrogen and prevented from generating yellow smoke.
In the embodiment of the invention, the concentration of the waste nitric acid mixed acid is 7-9 wt% (calculated by nitric acid); (2) the concentration of the ferrous water is 9-10 wt%; (3) the volume of the reaction kettle is 20m3After 1-2 tons of waste nitric acid is added into the reaction kettle, the heat exchanger is used for circularly exchanging heat, the heat exchanger is closed after the materials are heated to 75-85 ℃, then a valve for introducing the ferrous water is opened, the opening degree of the valve is controlled, and the introduction flow of the ferrous water is controlled to be 0.75-0.8m3The reaction temperature can be maintained at 65-70 ℃ due to the self-heat release of the reaction, the materials are circulated by a circulating pump instead of stirring, and the ferrous ion content of the reaction materials is monitored by sampling and measuring the ferrous ions during the stirring, so that the reaction endpoint (the ferrous ion content is about 0.2%) can be judged. In the production mode, because the amount of nitric acid is large and the reaction speed is high, the flow rate of ferrous iron water needs to be controlled by controlling the size of a valve so as to control the generation rate of nitrogen oxide; (4) the absorption mode of the spraying tail gas adopted in the nitric acid treatment experiment is as follows: tail gas generated by nitric acid process → clean water absorption → mixed reducing agent absorption → discharge, the tail gas is treated to reach the standard and discharged, and the standard is in accordance with NaPDEA hydrochloride spectrophotometry for measuring nitric oxide in solid pollution source exhaust gas and DB 4427-2001 atmospheric pollutant discharge limit
Example 1
(1) Volume per unit area of 10m3Adding 1 ton of waste nitric acid (calculated by nitric acid) 8.05 wt% into a reaction kettle, performing heat exchange by a heat exchanger in a circulating manner, heating materials to 75 ℃, closing the heat exchanger, opening a valve for introducing ferrous water, and controlling the opening of the valve so as to control the introduction flow of the ferrous water to be 0.8m3/h；
(2) The reaction is self-exothermic, the reaction temperature can be maintained at 65 ℃, the materials are circulated by a circulating pump to replace stirring, the ferrous ion content of the reaction materials is monitored and used for judging the reaction end point, and the ferrous ion content at the reaction end point is about 0.2%;
(3) tail gas absorption system: the tail gas firstly passes through a clear water absorption tower to wash acid mist in the tail gas; adding water into the sodium sulfide, the sodium sulfite and the sodium hydroxide in the mass ratio of 2:1:1 to prepare a mixed reducing agent solution with the effective content of 40%, absorbing and discharging nitrogen oxides, wherein the pH value of the reducing agent is maintained at about 13 by adding liquid alkali, simultaneously, the ORP value of the effective component of the reducing agent is ensured to be more than-600 mV, and the total nitrogen oxide is measured to be 109mg/m by discharge3Meets the standard HJT43-1999 Naphthylazamine hydrochloride spectrophotometry for measuring nitrogen oxides in solid pollution source exhaust gas and DB 4427-2001 atmospheric pollutant emission limit, namely the total nitrogen oxides are less than or equal to 120mg/m3。
Example 2
(1) Volume per unit area of 20m3Adding 2 tons of waste nitric acid (calculated by nitric acid) of 7.56 wt% into a reaction kettle, performing heat exchange by a heat exchanger in a circulating manner, heating materials to 80 ℃, closing the heat exchanger, opening a valve for introducing ferrous water, and controlling the opening of the valve so as to control the introduction flow of the ferrous water to be 0.75m3/h；
(2) The reaction is self-exothermic, the reaction temperature can be maintained at 69 ℃, the materials are circulated by a circulating pump to replace stirring, and the ferrous ion content of the reaction materials is monitored and used for judging the reaction end point;
(3) tail gas absorption system: the tail gas firstly passes through a clear water absorption tower to wash acid mist in the tail gas; then, adding a mixed reducing agent of sodium sulfide, sodium sulfite and sodium hydroxide with the mass ratio of 2:1:1 into two absorption towers, namely adding water into the sodium sulfide, the sodium sulfite and the sodium hydroxide with the mass ratio of 2:1:1 to prepare a mixed reducing agent solution with the effective content of 40%, carrying out nitrogen oxide absorption treatment and discharging, wherein the pH value of the reducing agent solution is maintained at about 13 by adding liquid alkali, and simultaneously, the ORP value of the effective component of the reducing agent solution is ensured to be at-600 mVAbove, total nitrogen oxides measured as emissions were 113mg/m3Meets the standard HJT43-1999 Naphthylazamine hydrochloride spectrophotometry for measuring nitrogen oxides in solid pollution source exhaust gas and DB 4427-2001 atmospheric pollutant emission limit, namely the total nitrogen oxides are less than or equal to 120mg/m3。
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A method for treating waste nitric acid is characterized by comprising the steps of heating a waste nitric acid solution to a certain temperature, adding a ferrous solution into the waste nitric acid solution, stirring, enabling tail gas released by reaction to pass through a clear water absorption tower, then through a mixed reducing agent absorption tower of sodium sulfide, sodium sulfite and sodium hydroxide according to the mass ratio of 2:1:1, absorbing nitrogen oxides, and then discharging.
2. The method for treating waste nitric acid according to claim 1, wherein: the heating temperature of the waste nitric acid solution is 75-85 ℃.
3. The method for treating waste nitric acid according to claim 1, wherein: after the stirring step, the method also comprises the step of monitoring the content of ferrous ions in the solution for judging the reaction endpoint.
4. The method of treating waste nitric acid according to claim 3, wherein: the ferrous ion content at the end of the reaction is 0.2%.
5. The method for treating waste nitric acid according to claim 1, wherein: the tail gas continuously passes through two mixed reducing agent absorption towers of sodium sulfide, sodium sulfite and sodium hydroxide with the mass ratio of 2:1: 1.
6. The method for treating waste nitric acid according to claim 5, wherein: the mixed reducing agent comprises a mixed reducing agent solution with the effective content of 40% prepared by adding sodium sulfide, sodium sulfite and sodium hydroxide according to the mass ratio of 2:1: 1.
7. The method of treating waste nitric acid according to claim 1 or 5, wherein: the method includes adding a liquid base to a mixed reducing agent solution to maintain a pH of the mixed reducing agent.
8. The method of treating waste nitric acid according to claim 7, wherein: the pH was maintained at 13.
9. The method for treating waste nitric acid according to claim 1, wherein: the method also includes detecting the emitted tail gas.
10. The method of treating waste nitric acid according to claim 7, wherein: the ORP value of the effective component of the mixed reducing agent is more than-600 mV.
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| CN202010036164.5A CN111097277A (en) | 2020-01-14 | 2020-01-14 | Waste nitric acid treatment method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109928438A (en) * | 2019-04-01 | 2019-06-25 | 陕西蕴德环保科技有限公司 | A kind of iron series water quality cleansing agent production catalyst removal of nitrogen oxide method |
| CN112915752A (en) * | 2021-01-25 | 2021-06-08 | 广东溢达纺织有限公司 | Flue gas and waste water treatment method and treatment device thereof |
| CN112978691A (en) * | 2021-03-09 | 2021-06-18 | 中国核电工程有限公司 | Method and device for preparing nitric acid from nitrogen oxide-containing tail gas and nuclear fuel post-treatment plant system |
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2020
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| CN102698709A (en) * | 2012-05-28 | 2012-10-03 | 常州大学 | Method for treating flue gas containing nitrogen oxide |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109928438A (en) * | 2019-04-01 | 2019-06-25 | 陕西蕴德环保科技有限公司 | A kind of iron series water quality cleansing agent production catalyst removal of nitrogen oxide method |
| CN112915752A (en) * | 2021-01-25 | 2021-06-08 | 广东溢达纺织有限公司 | Flue gas and waste water treatment method and treatment device thereof |
| CN112978691A (en) * | 2021-03-09 | 2021-06-18 | 中国核电工程有限公司 | Method and device for preparing nitric acid from nitrogen oxide-containing tail gas and nuclear fuel post-treatment plant system |
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