JP2005329304A - Method for treating nitric acid waste solution - Google Patents

Method for treating nitric acid waste solution Download PDF

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JP2005329304A
JP2005329304A JP2004148772A JP2004148772A JP2005329304A JP 2005329304 A JP2005329304 A JP 2005329304A JP 2004148772 A JP2004148772 A JP 2004148772A JP 2004148772 A JP2004148772 A JP 2004148772A JP 2005329304 A JP2005329304 A JP 2005329304A
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nitric acid
acid
treatment
reducing agent
organic reducing
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JP4239006B2 (en
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Osamu Takanobu
修 高信
Hiroshi Umetsu
浩 梅津
Ippei Amamoto
一平 天本
Ryohei Mori
良平 森
Yusuke Arima
雄介 有馬
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Mitsubishi Materials Corp
Japan Atomic Energy Agency
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Japan Nuclear Cycle Development Institute
Mitsubishi Materials Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating a nitric acid waste solution where the high decomposition rate of nitrate nitrogen can be attained under relatively mild conditions without requiring expensive catalysts and severe treating conditions such as high temperature-high pressure. <P>SOLUTION: The method for decomposing the component of nitric acid by adding an organic reducing agent to a nitric acid waste solution is characterized in that inorganic acid is added, and reaction is progressed in such a manner that the concentration of the acid upon the end of the decomposition treatment lies in the range from 0.3N to 1.0N, preferably, from 0.3N to 0.5N. It is preferable that the amount of the organic reducing agent to be added lies in the range from an amount equivalent to 1.0 time the amount of nitrate nitrogen in the waste solution to an amount equivalent to 1.5 times that, the inorganic acid is added before the treatment or under the treatment, heating is performed to a temperature at which boiling is not caused under ordinary pressure, and the organic reducing agent is gradually added in accordance with the generating conditions of gaseous nitrogen oxide, so as to decompose the component of nitric acid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、比較的高濃度の硝酸廃液であっても、廃液中の硝酸分を還元分解することによって、硝酸根を含む残渣を増加せずに、廃液中の硝酸態窒素を放流可能な濃度程度まで低下させることができ、かつ必要に応じて硝酸分を回収して再使用することができ、しかも反応条件が穏和な処理方法に関する。本発明の処理方法は、硝酸態窒素を多く含む廃液を排出処理する必要のある分野、例えば金属表面を酸洗処理する金属加工工場、あるいは核燃料を溶解処理する核燃料処理工場などの各種産業分野において広く適用することができる。   The present invention provides a concentration capable of discharging nitrate nitrogen in a waste liquid without increasing the residue containing nitrate radicals by reducing and decomposing the nitric acid content in the waste liquid even in a relatively high concentration nitric acid waste liquid. The present invention relates to a treatment method that can be reduced to a certain extent, and that the nitric acid content can be recovered and reused as required, and the reaction conditions are mild. The treatment method of the present invention is used in various industrial fields such as a metal processing factory for pickling a metal surface or a nuclear fuel treatment factory for dissolving nuclear fuel, in a field where waste liquid containing a large amount of nitrate nitrogen needs to be discharged. Can be widely applied.

近年、排水中の窒素分濃度の規制強化に伴い、排水中の硝酸態窒素を除去する技術に対する関心が高まっている。廃液中の硝酸分を分離除去する技術として、従来は蒸発法、イオン交換法、電気透析法などが知られている。これらの方法は硝酸分を濃縮分離して小容量の濃縮廃液とし、残りの液を排出可能な濃度に低下するものであるので、濃縮廃液中の硝酸分を無害化するためには、さらに濃縮廃液を処理する必要がある。   In recent years, interest in technology for removing nitrate nitrogen in wastewater has increased with the tightening of regulations on the concentration of nitrogen in wastewater. Conventionally known techniques for separating and removing nitric acid in waste liquid include evaporation, ion exchange, and electrodialysis. These methods concentrate and separate the nitric acid to make a small volume of concentrated waste liquid, and the remaining liquid is reduced to a concentration that can be discharged. Therefore, in order to render the nitric acid content in the concentrated waste liquid harmless, it is further concentrated. It is necessary to treat the waste liquid.

ところが、一般に濃縮廃液は硝酸分と共に種々の不純物も高濃度に含むので硝酸分のみを含む場合よりも無害化処理が難しく、中和処理して硝酸塩を含む残渣を析出させて乾燥硝酸塩の形態で分離し、さらにはこの硝酸塩残渣を高温で熱分解して酸化物に安定化させるなど、全体としては複雑で高コストの処理を行わざるを得なかった。   However, concentrated waste liquids generally contain various impurities at a high concentration together with nitric acid, so it is more difficult to detoxify than when only nitric acid is contained. In general, the nitrate residue was thermally decomposed at a high temperature to stabilize it into an oxide, and the entire process was complicated and expensive.

他方、硝酸分を化学反応によって分解し、最終的には窒素ガスにまで還元して無害化する方法も試みられてきた。例えば、硝酸を大量に使用する核燃料再処理工場では、核燃料物質を抽出した後の硝酸廃液を濃縮しながら有機還元剤で分解し、分解反応で発生した窒素酸化物(NOx)を水に吸収させて硝酸として再利用することが行われている。しかし、有機還元剤のみによる分解反応では、硝酸濃度が１Ｎ程度を下回ると反応速度が低下するため、分解処理を終了して中和濃縮せざるを得ず、やはり相当量の硝酸塩残渣が発生するという問題がある。   On the other hand, a method of decomposing nitric acid by a chemical reaction and finally reducing it to nitrogen gas to make it harmless has been tried. For example, in a nuclear fuel reprocessing plant that uses a large amount of nitric acid, the nitric acid waste liquid extracted from the nuclear fuel material is decomposed with an organic reducing agent while being concentrated, and nitrogen oxides (NOx) generated in the decomposition reaction are absorbed into water. It is reused as nitric acid. However, in the decomposition reaction using only the organic reducing agent, the reaction rate decreases when the concentration of nitric acid is less than about 1N, so the decomposition treatment must be terminated and neutralized and concentrated, and a considerable amount of nitrate residue is generated. There is a problem.

この他に、液相で特定の触媒と接触させて硝酸分を分解する湿式酸化分解法も提案されている（特許文献１、２）。この方法では、硝酸分は直接に窒素ガスに還元されて無害化されるが、反応活性を維持するための高温度域（100〜370℃）と液相を保つための高圧条件（１〜12MPa）を必要とし、このため反応容器の耐食性や反応熱を制御し得る硝酸根濃度との関係から処理可能な硝酸濃度に限界があり、低濃度の硝酸廃液処理に限定されると云う問題がある。さらに、高濃度硝酸廃液を加熱気化させ、触媒によって窒素酸化物(NOx)に分解し、これをさらにアンモニアと反応させて窒素ガスに還元する方法（特許文献３）も提案されている。しかし、この方法でも硝酸蒸気の分解反応には２００〜５５０℃の温度が必要であり、反応装置には過酷な条件である。   In addition, a wet oxidative decomposition method in which a nitric acid component is decomposed by contacting with a specific catalyst in a liquid phase has been proposed (Patent Documents 1 and 2). In this method, the nitric acid content is directly reduced to nitrogen gas and rendered harmless, but the high temperature range (100 to 370 ° C) for maintaining the reaction activity and the high pressure conditions (1 to 12 MPa for maintaining the liquid phase) Therefore, there is a limit to the concentration of nitric acid that can be treated from the relationship with the concentration of nitrate radical that can control the corrosion resistance of the reaction vessel and the heat of reaction. . Furthermore, a method has also been proposed in which a high-concentration nitric acid waste solution is heated and vaporized, decomposed into nitrogen oxides (NOx) with a catalyst, and further reacted with ammonia to reduce it to nitrogen gas (Patent Document 3). However, even in this method, a temperature of 200 to 550 ° C. is necessary for the decomposition reaction of nitric acid vapor, which is a severe condition for the reaction apparatus.

一方、常温付近の処理方法として、常温大気圧下で硝酸分を水素で還元して窒素ガスまで分解させる触媒が提案されている（特許文献４）。しかし、この触媒はｐＨ４以上でしか用いることができず、希薄硝酸を含む廃水の処理に限定される。またヒドラジンを水素供与体とし、２価の銅イオンを添加し、特定の触媒を用いてほぼ常温で硝酸を窒素ガスにまで還元する方法が提案されている（特許文献５）。この方法は、高濃度硝酸の処理も可能であるが、残渣源となる添加物を必要とし、また処理廃液のｐＨを１１.７以上の高アルカリにすることが望ましいので、多量の中和剤を必要とし、しかも条件によってはアンモニア態窒素が液中に残存するなどの問題がある。
特開平０７−１８５５６９号公報 特開２０００−１６７５７０号公報 特開平０８−３０９３３５号号公報 特開２００１−０００８６６号号公報 特開２００１−１２９５６５号号公報 On the other hand, as a treatment method near room temperature, a catalyst that reduces the nitric acid content with hydrogen at room temperature and atmospheric pressure to decompose it into nitrogen gas has been proposed (Patent Document 4). However, this catalyst can only be used at a pH of 4 or higher and is limited to the treatment of wastewater containing dilute nitric acid. In addition, a method has been proposed in which hydrazine is used as a hydrogen donor, divalent copper ions are added, and nitric acid is reduced to nitrogen gas at a normal temperature using a specific catalyst (Patent Document 5). Although this method can treat high-concentration nitric acid, it requires an additive as a residue source, and it is desirable to make the pH of the treatment waste liquid high alkali of 11.7 or more. Furthermore, depending on conditions, there is a problem that ammonia nitrogen remains in the liquid.
Japanese Patent Application Laid-Open No. 07-185569 JP 2000-167570 A Japanese Patent Laid-Open No. 08-309335 JP 2001-000866 A JP 2001-129565 A

以上のように、従来の処理技術では硝酸態窒素を廃液中から除去するには、高温高圧の厳しい反応条件を必要とし、あるいは処理液のｐＨを高く保つために多量の中和剤を加える必要があり、処理残渣が増加するなどの問題があった。本発明はこのような従来方法の問題を解決したものであり、廃液中の硝酸性窒素分を温和な条件下で簡便に分解除去し、残渣を増やさず、しかも必要に応じて硝酸を回収して再利用できる技術を提供するものである。   As described above, in order to remove nitrate nitrogen from waste liquid, conventional processing technology requires severe reaction conditions of high temperature and high pressure, or it is necessary to add a large amount of neutralizing agent to keep the pH of the processing liquid high. There was a problem that processing residue increased. The present invention solves such a problem of the conventional method, and easily decomposes and removes the nitrate nitrogen in the waste liquid under mild conditions, does not increase the residue, and collects nitric acid as necessary. Provide reusable technology.

本発明は、（１）硝酸廃液に有機還元剤を添加して硝酸分を分解する方法において、無機酸を添加して分解処理終了時の酸濃度が０.３N〜１.０Nの範囲になるように反応を進めることを特徴とする硝酸廃液の処理方法に関する。硝酸の還元分解においては、硝酸分解が進行すると廃液の酸濃度が低下するが、酸濃度が低くなり過ぎると分解反応が進行しない。本発明の処理方法は分解処理終了時の酸濃度が０.３N〜１.０N、好ましくは０.３Ｎ〜０.５Ｎの範囲になるように無機酸を添加して反応を行わせることによって硝酸の還元分解を進めて無害化し、液中の残留窒素濃度を排液可能な基準程度に低下させる。   According to the present invention, (1) in a method of decomposing nitric acid by adding an organic reducing agent to a nitric acid waste liquid, the acid concentration at the end of the decomposition treatment by adding an inorganic acid is in the range of 0.3N to 1.0N. It is related with the processing method of the nitric acid waste liquid characterized by advancing reaction. In the reductive decomposition of nitric acid, as the decomposition of nitric acid proceeds, the acid concentration of the waste liquid decreases, but when the acid concentration becomes too low, the decomposition reaction does not proceed. In the treatment method of the present invention, the reaction is carried out by adding an inorganic acid so that the acid concentration at the end of the decomposition treatment is in the range of 0.3N to 1.0N, preferably 0.3N to 0.5N. To reduce the residual nitrogen concentration in the liquid to a level that can be drained.

本発明の上記処理方法は、（２）有機還元剤の添加量が廃液の硝酸態窒素の１.０倍当量以上〜１.５倍当量以下である処理方法、（３）無機酸として硫酸または塩酸を用いる処理方法、（４）処理前または処理中に無機酸を添加し、常圧下で沸騰しない温度に加熱し、窒素酸化物ガスの発生状況に応じて有機還元剤を徐々に添加して硝酸分を分解させる処理方法を含む。   The above treatment method of the present invention includes (2) a treatment method in which the addition amount of the organic reducing agent is 1.0 to 1.5 times equivalent of nitrate nitrogen in the waste liquid, and (3) sulfuric acid or inorganic acid as an inorganic acid. Treatment method using hydrochloric acid, (4) Add inorganic acid before or during treatment, heat to a temperature that does not boil under normal pressure, and gradually add organic reducing agent according to the generation status of nitrogen oxide gas A treatment method for decomposing nitric acid is included.

本発明の処理方法は硝酸の分解効率が良いので有機還元剤の添加量は分解する硝酸分の１倍当量以上〜１.５倍当量以下で足りる。また、酸濃度を調整するために添加する無機酸としては中和処理のみで排出可能な硫酸または塩酸を用いることができる。さらに、本発明の処理方法は処理前または処理中に無機酸を添加し、常圧下で沸騰しない温度に加熱し、窒素酸化物ガスの発生状況に応じて有機還元剤を徐々に添加すると云う穏和な条件で反応を進めることによって、無害化放流できる程度まで廃液の硝酸を分解することができる。   Since the treatment method of the present invention has a good nitric acid decomposition efficiency, the amount of the organic reducing agent added is not less than 1 equivalent to not more than 1.5 equivalents of the nitric acid to be decomposed. In addition, as the inorganic acid added to adjust the acid concentration, sulfuric acid or hydrochloric acid that can be discharged only by neutralization treatment can be used. Furthermore, the treatment method of the present invention adds a mineral acid before or during the treatment, heats it to a temperature at which it does not boil under normal pressure, and gradually adds an organic reducing agent according to the generation state of nitrogen oxide gas. The nitric acid in the waste liquid can be decomposed to such an extent that it can be detoxified and discharged by advancing the reaction under various conditions.

〔具体的な説明〕
以下、本発明の分解処理方法を実施形態に基づいて具体的に説明する。
本発明の硝酸態窒素の分解処理方法は、処理すべき硝酸廃液に塩酸などの無機酸を加えて酸濃度の調整を行う。無機酸の添加は処理前でも良く、処理の途中でも良い。無機酸の添加量は処理終了時の酸濃度が０.３Ｎ〜１.０Ｎ、好ましくは０.３Ｎ〜０.５Ｎとなる量である。なお、硝酸の分解が進行すると硝酸による酸濃度は低下し、硝酸の全量が分解したときの酸濃度は添加した無機酸の量によって定まる。従って、硝酸の分解率が９９％程度以上であるとき、添加する無機酸の量は硝酸を除くこの無機酸による酸濃度が概ね０.３Ｎ〜１.０Ｎ、好ましくは０.３Ｎ〜０.５Ｎとなる量であればよい。溶液の酸濃度がこれより低いと硝酸の分解が十分に進まない。一方、酸濃度がこれより高いと残留する無機酸の中和に多量の塩基薬剤を必要とするようになるので好ましくない。 [Specific description]
Hereinafter, the decomposition processing method of the present invention will be specifically described based on embodiments.
In the method for decomposing nitrate nitrogen according to the present invention, an acid concentration is adjusted by adding an inorganic acid such as hydrochloric acid to a nitric acid waste liquid to be treated. The inorganic acid may be added before the treatment or during the treatment. The amount of the inorganic acid added is such that the acid concentration at the end of the treatment is 0.3N to 1.0N, preferably 0.3N to 0.5N. As the decomposition of nitric acid proceeds, the acid concentration due to nitric acid decreases, and the acid concentration when the total amount of nitric acid is decomposed is determined by the amount of added inorganic acid. Therefore, when the decomposition rate of nitric acid is about 99% or more, the amount of the inorganic acid added is such that the acid concentration by this inorganic acid excluding nitric acid is approximately 0.3 N to 1.0 N, preferably 0.3 N to 0.5 N. As long as it is an amount. If the acid concentration of the solution is lower than this, the decomposition of nitric acid does not proceed sufficiently. On the other hand, if the acid concentration is higher than this, a large amount of a basic agent is required for neutralizing the remaining inorganic acid, which is not preferable.

硝酸排液中の残留窒素分を低下させるには、無機酸の添加によって生成した窒素ガスを速やかに外部に排出するのが好ましく、空気あるいは窒素ガスなどを系内に流し、発生した窒素ガスを追い出すのが良い。なお、使用するガスは安全性の観点からは窒素ガスが好ましいが、実用上はコストの点から空気を用いても良い。   In order to reduce the residual nitrogen content in the nitric acid drainage, it is preferable to quickly discharge the nitrogen gas generated by the addition of the inorganic acid to the outside, and air or nitrogen gas is allowed to flow into the system, and the generated nitrogen gas is discharged. Good to kick out. The gas to be used is preferably nitrogen gas from the viewpoint of safety, but in practice, air may be used from the viewpoint of cost.

この酸性廃液を常圧下で沸騰しない程度、好ましくは９０℃程度に加熱し、この温度を維持しながら攪拌しつつ、窒素酸化物（ＮＯx）の発生状況に応じて有機還元剤を徐々に添加する。有機還元剤は硝酸を還元分解する活性を有し、自らは二酸化炭素と水に分解して無害化するものが用いられる。具体的にはホルムアルデヒドやギ酸などを用いることができる。有機還元剤の添加量は処理前の硝酸態窒素の１.０〜１.５倍当量が好ましい。この量が１倍当量より少ないと廃液中に硝酸態窒素が残留する。またこの量が１.５倍当量より多いと未反応の有機還元剤の残量が多くなるので好ましくない。   The acidic waste liquid is heated to an extent that it does not boil under normal pressure, preferably about 90 ° C., and the organic reducing agent is gradually added according to the state of generation of nitrogen oxides (NOx) while stirring while maintaining this temperature. . Organic reducing agents have the activity of reductively decomposing nitric acid, and those that decompose themselves into carbon dioxide and water to make them harmless are used. Specifically, formaldehyde or formic acid can be used. The addition amount of the organic reducing agent is preferably 1.0 to 1.5 times equivalent to nitrate nitrogen before the treatment. If this amount is less than 1 equivalent, nitrate nitrogen remains in the waste liquid. On the other hand, when the amount is more than 1.5 times equivalent, the remaining amount of the unreacted organic reducing agent increases, which is not preferable.

この操作によって廃液中の硝酸態窒素が還元分解し、窒素酸化物(ＮＯx)としてガス化する。好ましくは、廃液中の硝酸態窒素のほぼ９９％を窒素酸化物として除去することができる。有機還元剤としてホルムアルデヒドを用いた場合の分解反応を以下に示す。
２ＨＮＯ3＋ＨＣＨＯ → ＮＯ＋ＮＯ2＋２Ｈ2０＋ＣＯ2 By this operation, nitrate nitrogen in the waste liquid is reduced and decomposed and gasified as nitrogen oxides (NOx). Preferably, approximately 99% of the nitrate nitrogen in the waste liquid can be removed as nitrogen oxides. The decomposition reaction when formaldehyde is used as the organic reducing agent is shown below.
2HNO 3 + HCHO → NO + NO 2 + 2H 2 0 + CO 2

分解反応で発生した窒素酸化物（ＮＯx）は、例えば触媒存在下でアンモニアを作用させて還元分解するなどの方法によって窒素にまで分解し、無害化して大気に放出することができる。あるいは、必要に応じ、水に吸収させ、硝酸として回収して再利用することもできる。また、反応処理後の廃水にはＮａＣｌ等を添加して残留する有機還元剤の蟻酸やホルマリンなどを分解して無害化し、さらにＮａＯＨ等を添加して酸濃度を低下させ、規制値以下の水準にｐＨ調整して放流する。   Nitrogen oxides (NOx) generated in the decomposition reaction can be decomposed into nitrogen by a method such as reductive decomposition with the action of ammonia in the presence of a catalyst, detoxified and released into the atmosphere. Alternatively, if necessary, it can be absorbed in water, recovered as nitric acid, and reused. In addition, NaCl, etc., is added to the wastewater after the reaction treatment to decompose the remaining organic reducing agents such as formic acid and formalin, making them harmless, and further adding NaOH etc. to lower the acid concentration to a level below the regulation level. PH adjusted to release.

本発明の処理方法は塩酸や硫酸、ホルムアルムヒドなどの一般的な廉価な薬品のみを用い、高価な触媒や高温高圧などの厳しい処理条件を必要とせず、比較的温和な条件下で高い硝酸態窒素分解率を達成することができる。この処理した廃液には硝酸分が殆ど含まれていないので、簡単に中和処理して放流することができる。さらに、発生した窒素酸化物の排ガスも公知の触媒とアンモニアを使用した還元分解などの方法で分解し、無害化して大気放出することができる。あるいは、硝酸として回収することができる。   The treatment method of the present invention uses only general inexpensive chemicals such as hydrochloric acid, sulfuric acid, formaldehyde, etc., does not require harsh treatment conditions such as expensive catalysts and high temperature and pressure, and does not require high nitric acid under relatively mild conditions. The nitrogen decomposition rate can be achieved. Since this treated waste liquid contains almost no nitric acid, it can be easily neutralized and discharged. Further, the generated nitrogen oxide exhaust gas can be decomposed by a method such as reductive decomposition using a known catalyst and ammonia, detoxified and released into the atmosphere. Alternatively, it can be recovered as nitric acid.

以下に本発明の実施例を示す。
〔実施例〕
図１に示すように、密閉反応容器１０、ヒータ１１、コンデンサー１２、温度計１３、有機還元剤供給管路１４、掃気供給管路１５を備えた分解装置を用い、表１に示す量の塩酸を加えた硝酸水溶液を反応容器１０に入れ、これをヒータ１１で９０℃まで加熱し、容器内にホルマリン(HCHO)を数回に分けて滴下した。この滴下は１時間ごとに徐々に行った。酸濃度および反応時間と残留窒素濃度の関係を図２に示した。また、反応終了後の溶液中の残留窒素濃度を測定し、この結果を表１に示した。 Examples of the present invention are shown below.
〔Example〕
As shown in FIG. 1, the amount of hydrochloric acid shown in Table 1 was obtained using a decomposition apparatus equipped with a sealed reaction vessel 10, a heater 11, a condenser 12, a thermometer 13, an organic reducing agent supply line 14, and a scavenging supply line 15. The aqueous nitric acid solution added with was added to the reaction vessel 10, heated to 90 ° C. with the heater 11, and formalin (HCHO) was dropped into the vessel in several portions. This dropping was gradually performed every hour. The relationship between the acid concentration and reaction time and the residual nitrogen concentration is shown in FIG. Further, the residual nitrogen concentration in the solution after completion of the reaction was measured, and the result is shown in Table 1.

Figure 2005329304
Figure 2005329304

本発明の処理方法を実施する装置構成の概念図。The conceptual diagram of the apparatus structure which implements the processing method of this invention. 実施例における硝酸分解の結果を示すグラフ。The graph which shows the result of nitric acid decomposition | disassembly in an Example.

符号の説明Explanation of symbols

１０−密閉反応容器、１１−ヒータ、１２−コンデンサー、１３−温度計、１４−有機還元剤供給管路、１５−掃気供給管路。
10-sealed reaction vessel, 11-heater, 12-condenser, 13-thermometer, 14-organic reducing agent supply line, 15-scavenging supply line.

Claims (4)

硝酸廃液に有機還元剤を添加して硝酸分を分解する方法において、無機酸を添加して分解処理終了時の酸濃度が０.３N〜１.０Nの範囲になるように反応を進めることを特徴とする硝酸廃液の処理方法。   In the method of decomposing nitric acid by adding an organic reducing agent to the nitric acid waste liquid, the reaction is advanced so that the acid concentration at the end of the decomposition treatment is in the range of 0.3N to 1.0N by adding an inorganic acid. A method for treating nitric acid waste liquid. 有機還元剤の添加量が廃液の硝酸態窒素の１.０倍当量以上〜１.５倍当量以下である請求項１の処理方法。   The processing method according to claim 1, wherein the addition amount of the organic reducing agent is 1.0 to 1.5 times equivalent to nitrate nitrogen of the waste liquid. 無機酸として硫酸または塩酸を用いる請求項１または２の処理方法。   The treatment method according to claim 1 or 2, wherein sulfuric acid or hydrochloric acid is used as the inorganic acid. 処理前または処理中に無機酸を添加し、常圧下で沸騰しない温度に加熱し、窒素酸化物ガスの発生状況に応じて有機還元剤を徐々に添加して硝酸分を分解させる請求項１、２または３の処理方法。
An inorganic acid is added before or during the treatment, heated to a temperature that does not boil under normal pressure, and an organic reducing agent is gradually added according to the generation state of nitrogen oxide gas to decompose the nitric acid content. Processing method 2 or 3.
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JP2013031829A (en) * 2011-07-07 2013-02-14 Mitsubishi Materials Corp Method for treating nitric acid-containing solution
CN115043382A (en) * 2022-06-24 2022-09-13 中国原子能科学研究院 Method for producing nitrogen dioxide and device for continuously producing nitrogen dioxide
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Publication number Priority date Publication date Assignee Title
WO2007083588A1 (en) * 2006-01-19 2007-07-26 Japan Nuclear Fuel Limited Sodium salt recycling system for use in wet reprocessing of used nuclear fuel
EP1975945A1 (en) * 2006-01-19 2008-10-01 Japan nuclear fuel limite Sodium salt recycling system for use in wet reprocessing of used nuclear fuel
JPWO2007083588A1 (en) * 2006-01-19 2009-06-11 日本原燃株式会社 Sodium salt recycling system in wet reprocessing of spent nuclear fuel
US7666370B2 (en) 2006-01-19 2010-02-23 Japan Nuclear Fuel Limited Sodium salt recycling process for use in wet reprocessing process of spent nuclear fuel
JP5038160B2 (en) * 2006-01-19 2012-10-03 日本原燃株式会社 Sodium salt recycling system in wet reprocessing of spent nuclear fuel
EP1975945A4 (en) * 2006-01-19 2014-09-17 Japan Nuclear Fuel Limite Sodium salt recycling system for use in wet reprocessing of used nuclear fuel
JP2013031829A (en) * 2011-07-07 2013-02-14 Mitsubishi Materials Corp Method for treating nitric acid-containing solution
CN115043382A (en) * 2022-06-24 2022-09-13 中国原子能科学研究院 Method for producing nitrogen dioxide and device for continuously producing nitrogen dioxide
CN115057418A (en) * 2022-06-24 2022-09-16 中国原子能科学研究院 Method and device for producing nitrogen dioxide

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