JP3097241B2 - Method for removing chlorate from aqueous alkali chloride solution - Google Patents
Method for removing chlorate from aqueous alkali chloride solutionInfo
- Publication number
- JP3097241B2 JP3097241B2 JP03322413A JP32241391A JP3097241B2 JP 3097241 B2 JP3097241 B2 JP 3097241B2 JP 03322413 A JP03322413 A JP 03322413A JP 32241391 A JP32241391 A JP 32241391A JP 3097241 B2 JP3097241 B2 JP 3097241B2
- Authority
- JP
- Japan
- Prior art keywords
- chlorate
- salt water
- decomposition
- decomposition tank
- hydrochloric acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Description
【０００１】[0001]
【産業上の利用分野】本発明は陽イオン交換膜法塩化ア
ルカリ電解に供する塩化アルカリ水溶液（以下「塩水」
と称する）の精製に関するものであり、具体的には循環
塩水中に蓄積してくる塩素酸塩を除去する方法に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous solution of alkali chloride (hereinafter referred to as "salt water") to be subjected to cation exchange membrane method alkali chloride electrolysis.
And more specifically to a method for removing chlorate accumulated in circulating saline.
【０００２】[0002]
【従来の技術】塩水中の塩素酸塩を除去する方法は、こ
れまでいくつか開示されている。その代表的な方法は、
塩水に塩酸を添加し、以下の反応、 ＣｌＯ３ −＋２ＨＣｌ→ＣｌＯ２＋１／２Ｃｌ２＋Ｃｌ−＋Ｈ２Ｏ・・（１） ＣｌＯ３ −＋６ＨＣｌ→３Ｃｌ２＋Ｃｌ−＋３Ｈ２Ｏ・・・（２） により塩素酸塩を分解し、除去する方法であるが、塩酸
と塩素酸塩との反応は遅いため、上記方法では塩素酸塩
の除去に時間がかかるという問題があった。そこで従
来、塩水中の塩素酸塩の除去を速やかに行なうために、
塩水中の塩化アルカリを飽和させた後、塩酸を添加する
方法（特開昭５９−２０４８３号公報）、塩水中の塩酸
濃度を１５０ｇ／リットルを越える値に保持する方法
（特開昭５７−１９１２２５号公報）などが提案されて
いる。しかしながら、塩化アルカリを飽和させた後、塩
酸を添加する方法では塩酸を添加した際に塩の析出トラ
ブルが発生し易く、また塩水中の塩酸濃度を１５０ｇ／
リットルを越える値に維持する方法では塩素酸塩を分解
した後の塩水中塩酸濃度が必要以上に高くなってしま
う。従って、これらの方法においては析出する塩を処理
する工程や、塩酸濃度を下げるために中和用アルカリを
塩水に添加する工程など複雑な後処理工程や薬剤を必要
とするという問題がある。ところで、塩水に比較的少な
い量の塩酸を添加して塩水中の塩素酸塩を分解する場
合、上記（１）式から明らかなように二酸化塩素が生成
する。そこで、上述した塩水中の塩素酸塩の分解、除去
の際に、生成する二酸化塩素を加熱により塩素と酸素に
分解し、有用な塩素を回収すること（特開昭６１−１０
１４０２号公報）が提案されている。しかしながら、該
方法は二酸化塩素の分解、生成する塩素と酸素の分離等
の工程が必要であり、操作及び工程が複雑になるという
問題点を有している。2. Description of the Related Art Several methods for removing chlorate in salt water have been disclosed. The typical method is
Hydrochloric acid was added to the salt water, the following reaction, ClO 3 - + 2HCl → ClO 2 + 1 / 2Cl 2 + Cl - + H 2 O ·· (1) ClO 3 - + 6HCl → 3Cl 2 + Cl - + 3H 2 O ··· (2) However, since the reaction between hydrochloric acid and chlorate is slow, there is a problem that it takes time to remove chlorate in the above method. Therefore, conventionally, in order to quickly remove chlorate in salt water,
A method of adding hydrochloric acid after saturating an alkali chloride in salt water (JP-A-59-20483) and a method of maintaining the concentration of hydrochloric acid in salt water at a value exceeding 150 g / liter (JP-A-57-191225). Publication). However, in the method of adding hydrochloric acid after saturating the alkali chloride, a problem of salt precipitation easily occurs when hydrochloric acid is added.
If the method is maintained at a value exceeding 1 liter, the hydrochloric acid concentration in the salt water after the chlorate is decomposed becomes unnecessarily high. Therefore, these methods have a problem that complicated post-treatment steps and chemicals are required, such as a step of treating precipitated salts and a step of adding a neutralizing alkali to the brine to reduce the concentration of hydrochloric acid. When a relatively small amount of hydrochloric acid is added to the salt water to decompose the chlorate in the salt water, chlorine dioxide is generated as is apparent from the above equation (1). Therefore, when decomposing and removing the chlorate in the above-mentioned salt water, the chlorine dioxide produced is decomposed into chlorine and oxygen by heating, and useful chlorine is recovered (Japanese Patent Laid-Open No. 61-10 / 1986).
No. 1402) has been proposed. However, this method requires steps such as decomposition of chlorine dioxide and separation of generated chlorine and oxygen, and has a problem that the operation and the steps are complicated.
【０００３】また、塩水中の塩素酸塩を除去する別の方
法として、イオン交換膜法塩化アルカリ電解槽に供給さ
れる循環塩水経路に触媒層を設け、水素又は水素を含む
ガスを通じて塩素酸塩を分解して除去する方法（特開昭
５６−１６３２８６号公報）があるが、この方法では触
媒の溶出による不純物の増加及び工程が複雑となりコス
トが膨大になるという問題点がある。更に循環塩水の一
部を抜き出して冷却し、塩素酸塩を晶出分離することに
より塩素酸塩を除去する方法（特開昭５１−１４４３９
９号公報）も知られているが、この方法では塩素酸塩の
除去が十分に行なわれず、またプロセスが複雑となり、
しかも冷却コストが多大になるという問題がある。その
他にも、塩水中に亜硫酸ソ−ダ、硫化水素等の還元剤を
添加して塩素酸塩を除去する方法（特開昭５３−１２３
３９６号公報あるいは特開昭６０−７７９８２号公
報）、イオン交換膜共存酸性下において塩素酸塩を分解
し、除去する方法（特開昭６３−１２９０１５号公報）
なども提案されているが、これらの方法には各々、硫酸
塩の蓄積、及び薬剤コストが多大となるという問題、塩
素酸塩の分解率が低く、工業化し難いという問題があ
る。[0003] As another method for removing chlorate in salt water, a catalyst layer is provided in a circulating salt water path supplied to an ion-exchange membrane alkali chloride electrolytic cell, and chlorate is passed through hydrogen or a gas containing hydrogen. There is a method of decomposing and removing (Japanese Patent Application Laid-Open No. 56-163286). However, this method has a problem that the amount of impurities increases due to elution of the catalyst, the process becomes complicated, and the cost becomes enormous. Further, a method of removing the chlorate by extracting a part of the circulating salt water, cooling, and crystallizing and separating the chlorate (JP-A-51-14439)
No. 9) is also known, but in this method, chlorate is not sufficiently removed, and the process becomes complicated.
In addition, there is a problem that the cooling cost becomes large. In addition, a method of removing chlorate by adding a reducing agent such as sodium sulfite or hydrogen sulfide to salt water (Japanese Patent Application Laid-Open No. 53-123)
396 or JP-A-60-77982), a method of decomposing and removing chlorate in the presence of an acid in the presence of an ion-exchange membrane (JP-A-63-129015).
Although these methods have been proposed, each of these methods has a problem that the accumulation of sulfates and the cost of chemicals are large, and a problem that the decomposition rate of chlorate is low and industrialization is difficult.
【０００４】[0004]
【発明が解決しようとする課題】本発明の目的は、塩酸
を用いて塩水中の塩素酸塩を除去する方法において、塩
酸の使用量が少ない条件下で塩素酸塩の分解を速やかに
進行させ且つ、効率的、効果的に塩水を精製し、更に有
効な高純度の塩素を回収する方法を提供することにあ
る。SUMMARY OF THE INVENTION An object of the present invention is to provide a method for removing chlorate in salt water using hydrochloric acid, in which the decomposition of chlorate proceeds rapidly under conditions where the amount of hydrochloric acid used is small. Another object of the present invention is to provide a method for efficiently and effectively purifying salt water and recovering more effective high-purity chlorine.
【０００５】[0005]
【課題を解決するための手段】本発明者らは上記課題を
解決するため、塩水中の塩素酸塩の分解方法を鋭意検討
した結果、塩水中に塩酸を添加した後、これを減圧下で
しかも一定圧力範囲に維持し、及び／又は反応液を分解
槽内で上昇流とすることにより、効果的、効率的に塩素
酸塩を除去でき、さらに高純度の塩素ガスを回収できる
ことを見出し、本発明を完成するに至った。すなわち本
発明は、陽イオン交換膜法塩化アルカリ水溶液電解に供
する塩化アルカリ水溶液に塩酸を添加した反応液を、分
解槽内にて絶対圧６００ｍｍＨｇ以下、反応液の飽和蒸
気圧以上に維持し、及び／又は反応液を分解槽下部より
供給し分解槽内を上昇流とすることを特徴とする塩化ア
ルカリ水溶液中の塩素酸塩の除去方法である。本発明の
方法によれば、塩素酸塩の分解に必要な塩酸量を少なく
でき、効率的、効果的に塩水中の塩素酸塩を分解し除去
することができる。特に、反応液を、分解槽内にて絶対
圧６００ｍｍＨｇ以下、反応液の飽和蒸気圧以上に維持
し、かつ反応液を分解槽下部より供給し分解槽内で上昇
流とするとその効果は大きく、さらに効率的、効果的に
塩水中の塩素酸塩を分解し除去することができる。ま
た、塩素酸塩の分解により生じる生成物は塩化アルカリ
と有用な塩素となり、これら生成物は有効に活用され
る。Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on a method for decomposing chlorate in salt water. As a result, after adding hydrochloric acid to the salt water, the hydrochloric acid was added under reduced pressure. In addition, it was found that chlorate can be effectively and efficiently removed and high-purity chlorine gas can be recovered by maintaining the pressure within a certain range and / or increasing the flow rate of the reaction solution in the decomposition tank. The present invention has been completed. That is, the present invention provides a reaction solution obtained by adding hydrochloric acid to an alkali chloride aqueous solution to be subjected to cation exchange membrane method alkali chloride aqueous solution electrolysis, maintaining an absolute pressure of 600 mmHg or less in a decomposition tank, and a saturated vapor pressure of the reaction solution or more, and A method for removing chlorate from an aqueous alkali chloride solution, characterized in that a reaction liquid is supplied from the lower part of the decomposition tank and the inside of the decomposition tank is made to flow upward. According to the method of the present invention, the amount of hydrochloric acid required for the decomposition of chlorate can be reduced, and the chlorate in the salt water can be decomposed and removed efficiently and effectively. In particular, when the reaction solution is maintained at an absolute pressure of 600 mmHg or less and a saturated vapor pressure of the reaction solution or more in the decomposition tank, and the reaction liquid is supplied from the lower part of the decomposition tank and is made to flow upward in the decomposition tank, the effect is large. Further, the chlorate in the salt water can be decomposed and removed efficiently and effectively. In addition, products generated by the decomposition of chlorate become alkali chloride and useful chlorine, and these products are effectively used.
【０００６】以下、本発明を詳細に説明する。Hereinafter, the present invention will be described in detail.
【０００７】分解槽内を絶対圧６００ｍｍＨｇ以下、反
応液の飽和蒸気圧以上に維持する場合、塩水としては、
塩化ナトリウム、塩化カリウムなどの水溶液を示す。ま
た塩水の濃度は、通常の塩水電解に供される塩水濃度
（１５０〜３００ｇ／リットル）程度であれば本法を効
果的に適用することができる。When the pressure inside the decomposition tank is maintained at an absolute pressure of 600 mmHg or less and a saturated vapor pressure of the reaction solution or more, the salt water is
Shows aqueous solutions of sodium chloride, potassium chloride, etc. In addition, the present method can be effectively applied if the concentration of the salt water is about the salt water concentration (150 to 300 g / liter) used for normal salt water electrolysis.
【０００８】本法では、塩水中に塩酸が添加されるが、
この塩酸の添加は分解槽への送液配管内で行なっても、
分解槽内で行なっても良く、特に塩水と塩酸との均一反
応、操作の面から前者による添加が好ましい。このと
き、添加する塩酸量は多いほど効率良く塩水中の塩素酸
塩を分解することができるが、この塩酸の添加量が多す
ぎる場合、塩素酸塩の分解後にアルカリを用いて過剰に
添加した塩酸を中和する必要が生じるおそれがあるこ
と、本法によれば塩素酸塩の分解を効果的、効率的に行
なうことができることなどから、添加する塩酸量は少な
くすることが好ましい。塩酸の添加量は、塩水中の塩酸
量の合量が塩水中の塩素酸塩１モル当たり１０〜５０倍
モルとすることが好ましく、更には１５〜３０倍モルが
好ましい。また、塩酸ガスによって塩水中に塩酸を添加
しても差支えない。In this method, hydrochloric acid is added to the salt water.
Even if this addition of hydrochloric acid is performed in the liquid supply pipe to the decomposition tank,
The addition may be carried out in a decomposition tank, and in particular, the former addition is preferred from the viewpoint of a uniform reaction between salt water and hydrochloric acid and operation. At this time, the larger the amount of hydrochloric acid to be added, the more efficiently the chlorate in the salt water can be decomposed.However, when the amount of the hydrochloric acid added is too large, the chlorate is excessively added using an alkali after the decomposition of the chlorate. It is preferable to reduce the amount of hydrochloric acid to be added because there is a possibility that the hydrochloric acid needs to be neutralized, and according to the present method, the chlorate can be effectively and efficiently decomposed. The amount of hydrochloric acid added is preferably 10 to 50 times, and more preferably 15 to 30 times, the molar amount of hydrochloric acid in the salt water per 1 mol of the chlorate in the salt water. Also, hydrochloric acid may be added to the salt water by hydrochloric acid gas.
【０００９】次に、上述の塩水に塩酸を添加した反応液
を分解槽内に維持するが、本法では分解槽内の圧力（絶
対圧）を６００ｍｍＨｇ以下、反応液の飽和蒸気圧以上
に維持する。このことにより、塩素酸塩の分解が効果的
に促進される。この分解槽内の絶対圧が６００ｍｍＨｇ
よりも圧力が高い場合、塩酸による塩素酸塩の分解効果
は小さくなり、６００ｍｍＨｇ以下で初めてその効果は
顕著となる。一方、分解槽内の絶対圧が反応液の飽和蒸
気圧よりも圧力が低い場合、水蒸気が多量発生し、不必
要な多大な熱エネルギ−を消費するだけでなく、発生塩
素中の水分含量が増すことになり、水との分離が必要と
なり、更に塩素酸塩の分解効果はそれ程大きくならな
い。又、水蒸気が生成する時に、反応液から蒸発熱を奪
う為、反応温度の低下がみられ、そのため反応速度が遅
くなる。従って、分解槽内の絶対圧を本発明の範囲にす
ることによってのみ、大きな効果が得られる。なお、上
記絶対圧の更に望ましい範囲は、５００ｍｍＨｇ以下、
反応液の飽和蒸気圧よりも１０ｍｍＨｇ高い圧力以上で
ある。また、反応液の飽和蒸気圧は、塩水の種類、塩素
酸塩濃度、不純物種とその濃度によって異なるが、これ
らは適宜求められる値であり、例えば温度９０℃の塩化
ナトリウム水溶液の場合、ＮａＣｌ１５０ｇ／リットル
で約４７０ｍｍＨｇ、２００ｇ／リットルで約４５０ｍ
ｍＨｇ、２５０ｇ／リットルで約４２０ｍｍＨｇであ
る。分解槽内の減圧は、真空ポンプを用いたり、水また
はスチ−ムエジェクタ−を用いることなどにより行なう
ことができるが、特に温水エジェクタ−を用いれば、エ
ジェクタ−吐出液とガスをタンクに静置させ、液部をエ
ジェクタ−に循環し、ガス部を回収、脱水して副生高純
度塩素ガス又は液化塩素とすることができるので好まし
い。Next, the reaction liquid obtained by adding hydrochloric acid to the above-mentioned salt water is maintained in the decomposition tank. In this method, the pressure (absolute pressure) in the decomposition tank is maintained at 600 mmHg or less and the saturated vapor pressure of the reaction liquid or more. I do. This effectively promotes chlorate decomposition. The absolute pressure in this decomposition tank is 600 mmHg
When the pressure is higher than the pressure, the effect of decomposing chlorate by hydrochloric acid becomes small, and the effect becomes significant only at 600 mmHg or less. On the other hand, when the absolute pressure in the decomposition tank is lower than the saturated vapor pressure of the reaction solution, a large amount of water vapor is generated, which not only consumes a large amount of unnecessary heat energy, but also reduces the water content in the generated chlorine. This requires separation from water, and the chlorate decomposition effect is not so great. In addition, when steam is generated, heat of evaporation is removed from the reaction solution, so that the reaction temperature is lowered, and the reaction speed is reduced. Therefore, a great effect can be obtained only by setting the absolute pressure in the decomposition tank within the range of the present invention. Note that a more desirable range of the absolute pressure is 500 mmHg or less,
The pressure is 10 mmHg higher than the saturated vapor pressure of the reaction solution. The saturated vapor pressure of the reaction solution varies depending on the type of salt water, chlorate concentration, impurity type and its concentration, and these are values that are appropriately determined. For example, in the case of a 90 ° C. sodium chloride aqueous solution, NaCl 150 g / About 470mmHg in liter, about 450m in 200g / L
The mHg is about 420 mmHg at 250 g / liter. The pressure in the decomposition tank can be reduced by using a vacuum pump or water or a steam ejector. Particularly, when a hot water ejector is used, the ejected liquid and gas are allowed to stand still in the tank. The liquid portion is preferably circulated to the ejector, and the gas portion is recovered and dehydrated to obtain high-purity by-product chlorine gas or liquefied chlorine.
【００１０】本法において用いられる分解槽は特に限定
されず、例えばタンク式でも塔式であってもよい。ま
た、塩水中の塩素酸塩の分解を効果的に行なう場合、タ
ンク式では攪拌式、塔式では無攪拌、無充填とすること
が好ましい。更に分解槽中の液深は１ｍ以上、特に２ｍ
以上とすることが好ましく、このことにより副生二酸化
塩素量を抑制することができる。また、塩素酸塩の分解
は、連続式、回分式いずれにおいても実施できるが、生
産性、操作性より、連続式による実施が好ましい。又、
反応液を分解槽下部より供給し分解槽内を上昇流とする
場合、塩水としては、塩化ナトリウム、塩化カリウムな
どの水溶液を好適にもちいることができる。また、塩水
の濃度は通常の塩水電解に供される塩水濃度（１５０〜
３００ｇ／リットル）程度であれば本法を効果的に適用
することができる。The decomposition tank used in the present method is not particularly limited, and may be, for example, a tank type or a tower type. When the chlorate in the salt water is effectively decomposed, it is preferable that the tank type is a stirring type, and the tower type is a non-stirring and non-filling type. Furthermore, the liquid depth in the decomposition tank is 1 m or more, especially 2 m
It is preferable that the amount be as described above, whereby the amount of by-produced chlorine dioxide can be suppressed. The chlorate can be decomposed by a continuous method or a batch method, but the continuous method is preferable in terms of productivity and operability. or,
In the case where the reaction solution is supplied from the lower part of the decomposition tank so as to flow upward in the decomposition tank, an aqueous solution of sodium chloride, potassium chloride or the like can be suitably used as the salt water. Further, the concentration of the salt water is the concentration of the salt water used for normal salt water electrolysis (150 to
This method can be effectively applied if it is about 300 g / liter).
【００１１】本法では、塩水中に塩酸が添加されるが、
この塩酸の添加は分解槽への送液配管内で行っても、分
解槽下部で行ってもよい。特に塩水と塩酸との均一反
応、操作の面から分解槽への送液配管内に添加するのが
好ましく、更にそこで機械混合するのが好ましい。この
とき、添加する塩酸量は多いほど効率よく塩水中の塩素
酸塩を分解できるが、この塩酸の添加量が多すぎる場
合、塩素酸塩の分解後にアルカリを用いて過剰に添加し
た塩酸を中和する必要が生じるおそれがあること、本法
によれば塩素酸塩の分解を効果的、効率的に行うことが
できることなどから、添加する塩酸量は少なくすること
が好ましい。塩酸の添加量は、塩水中の塩素酸塩１モル
当り１０〜５０倍モルとするのが好ましく、更には１５
〜３０倍モルが好ましい。又、塩酸ガスによって、塩水
中に塩酸を添加しても差支えない。In this method, hydrochloric acid is added to salt water.
The addition of the hydrochloric acid may be performed in a liquid feed pipe to the decomposition tank or at a lower part of the decomposition tank. In particular, from the viewpoint of the uniform reaction of salt water and hydrochloric acid and the operation, it is preferable to add the solution to the feed pipe to the decomposition tank, and it is further preferable to perform mechanical mixing there. At this time, the larger the amount of hydrochloric acid added, the more efficiently the chlorate in the salt water can be decomposed.However, if the amount of hydrochloric acid added is too large, the excess hydrochloric acid added with an alkali after the decomposition of the chlorate is used. It is preferable to reduce the amount of hydrochloric acid to be added, since there is a possibility that the addition of the hydrochloric acid may be required, and the method can effectively and efficiently decompose the chlorate. The amount of hydrochloric acid to be added is preferably 10 to 50 times mol per mol of chlorate in salt water, and more preferably 15 to 50 mol.
It is preferably up to 30-fold mol. Also, hydrochloric acid may be added to the salt water by hydrochloric acid gas.
【００１２】次に、上述の塩水に塩酸を添加した反応液
を分解槽下部より供給し分解槽内を上昇流とするが、こ
の事により、塩水中の塩素酸塩の分解が効果的に促進さ
れる。Next, a reaction solution obtained by adding hydrochloric acid to the above-mentioned salt water is supplied from the lower part of the decomposition tank to make the inside of the decomposition tank an upward flow, whereby the decomposition of chlorate in the salt water is effectively promoted. Is done.
【００１３】分解槽の形、大きさなどは特に問わない
が、反応液がよりピストン流れに近い状態となるように
細長い塔式の反応器とするのが好ましい。ここで、ピス
トン流れとは液の流れの方向に流体の混合や拡散が起こ
らず、流れと直角な平面内で速度分布がない理想的な流
れのことをいうが、反応液がピストン流れでも、下降流
の場合は分解効率が極めて低くなる。その理由として
は、生成塩素ガスの抜けが悪くなり、反応液の真の滞在
時間が減少すること、後述する逆反応が考えられる。更
には生成塩素ガス中の二酸化塩素の割合が高くなる。
又、分解槽に攪拌機を備えても構わない。しかしなが
ら、攪拌機費用、攪拌の為のエネルギ−を必要とするだ
けでなく、塩素酸塩分解効率は向上しない。攪拌機を設
けないで行うのが、装置、操作面で有利であり、且つ分
解効率が高いので好ましい。The shape and size of the decomposition tank are not particularly limited, but it is preferable to use a slender tower-type reactor so that the reaction liquid is in a state closer to the piston flow. Here, the piston flow refers to an ideal flow in which no mixing or diffusion of the fluid occurs in the direction of the liquid flow, and there is no velocity distribution in a plane perpendicular to the flow. In the case of a downward flow, the decomposition efficiency is extremely low. It is considered that the reason for this is that the generated chlorine gas is less likely to escape and the true residence time of the reaction solution is reduced, and the reverse reaction described later. Further, the ratio of chlorine dioxide in the generated chlorine gas increases.
Further, a stirrer may be provided in the decomposition tank. However, not only is the cost of the stirrer required, but also energy for stirring is required, and the chlorate decomposition efficiency is not improved. It is preferable to perform the process without a stirrer because it is advantageous in terms of equipment and operation and the decomposition efficiency is high.
【００１４】分解槽は細長い塔式が良く、具体的には塔
の内径を０．０３〜３ｍ、分解槽中の液深０．５〜２０
ｍとするのが好ましく、更には内径０．０４〜２ｍ、分
解槽中の液深２〜１５ｍとするのがより好ましい。The decomposition tank is preferably an elongated tower type. Specifically, the inner diameter of the tower is 0.03 to 3 m, and the liquid depth in the decomposition tank is 0.5 to 20.
m, more preferably 0.04 to 2 m in inner diameter and 2 to 15 m in liquid depth in the decomposition tank.
【００１５】内径が小さ過ぎると圧力損失が大きく、装
置、操作が繁雑となり、又、塩素ガス気泡の影響によ
り、液の上下混合が大きくなり、分解効率も低下する。
内径が大き過ぎると、液の上下混合が大きくなり、分解
効率が低下する。If the inner diameter is too small, the pressure loss will be large, and the equipment and operation will be complicated, and the mixing of the liquid up and down will be large and the decomposition efficiency will be reduced due to the influence of chlorine gas bubbles.
If the inside diameter is too large, the up-and-down mixing of the liquid will increase, and the decomposition efficiency will decrease.
【００１６】分解槽の液深については、小さ過ぎると液
の上下混合が大きくなり、分解効率が低下し、大き過ぎ
ると装置費用が嵩み、操作が繁雑となる。With respect to the liquid depth of the decomposition tank, if the liquid depth is too small, the up and down mixing of the liquid becomes large, and the decomposition efficiency is lowered. If the liquid depth is too large, the equipment cost increases and the operation becomes complicated.
【００１７】又、液深については、大きい場合、分解槽
を複数とし、直列につないでも良い。その場合、生成塩
素ガスは各分解槽毎に分離回収するのが好ましい。When the liquid depth is large, a plurality of decomposition tanks may be connected in series. In this case, it is preferable to separate and collect the generated chlorine gas in each decomposition tank.
【００１８】塔式の分解槽にできない場合、通常のタン
ク式の分解槽を用いても良い。当然、この時も分解槽内
を上昇流とする。タンク式の分解槽では、液の上下混合
が大きくなり幾分分解率は低下する。タンク式の分解槽
で分解効率を高めるには、分解槽の液流れ方向と同一方
向即ち、縦方向に前述した塔式分解槽内径のパイプを挿
入する、格子状の仕切り板を設置する、等の分解槽分割
方法を採用すれば良い。分割された部分の面積は、前述
した塔式分解槽の断面積に相当する値、即ち７ｃｍ２以
上７ｍ２以下とするのが好ましく、１２ｃｍ２以上３ｍ
２以下とするのがより好ましい。さらに好ましくは１２
ｃｍ２以上０．５ｍ２以下である。この場合、分解槽中
の液深は前述した塔式の分解槽の値が好ましい。又、分
解槽内の反応液の上昇速度は塔式、タンク式いずれの場
合も０．３〜４０ｍ／Ｈｒが好ましく、更には０．５〜
２５ｍ／Ｈｒがより好ましい。この値は分解槽中の反応
液量と反応液通液速度から算出したものである。この値
が大きすぎると圧力損失が大きくなり、又装置が長くな
るので装置費用が嵩み、操作が繁雑となる。又、値が小
さいと、液の上下混合が大きくなり分解効率が低下す
る。When a tower-type decomposition tank cannot be used, an ordinary tank-type decomposition tank may be used. Naturally, also at this time, the inside of the decomposition tank is set to the upward flow. In a tank-type decomposition tank, the up-and-down mixing of the liquid becomes large and the decomposition rate is somewhat reduced. In order to increase the decomposition efficiency in a tank-type decomposition tank, the pipe having the inner diameter of the tower-type decomposition tank described above is inserted in the same direction as the liquid flow direction of the decomposition tank, that is, a grid-like partition plate is installed. May be adopted. The area of the divided portion is preferably a value corresponding to the cross-sectional area of the above-mentioned tower type decomposition tank, that is, 7 cm 2 or more and 7 m 2 or less, and 12 cm 2 or more and 3 m 2 or more.
More preferably, it is set to 2 or less. More preferably, 12
cm 2 or more and 0.5 m 2 or less. In this case, the liquid depth in the decomposition tank is preferably the value of the above-described tower-type decomposition tank. The rate of rise of the reaction solution in the decomposition tank is preferably 0.3 to 40 m / Hr in both the tower type and the tank type, and more preferably 0.5 to 40 m / Hr.
25 m / Hr is more preferred. This value was calculated from the amount of the reaction solution in the decomposition tank and the flow rate of the reaction solution. If this value is too large, the pressure loss increases, and the length of the device increases, so that the cost of the device increases and the operation becomes complicated. On the other hand, if the value is small, the upper and lower mixing of the liquid becomes large, and the decomposition efficiency decreases.
【００１９】分解形式は、連続式となり生産性、操作性
は向上する。The disassembly type is a continuous type, and productivity and operability are improved.
【００２０】塩水に塩酸を添加した反応液を、分解槽に
て絶対圧６００ｍｍＨｇ以下、反応液の飽和蒸気圧以上
に維持し、かつ反応液を分解槽下部より供給し分解槽内
を上昇流とする場合、極めて効率良く塩素酸塩を分解で
きる。使用する塩水としては、前述した通りである。The reaction solution obtained by adding hydrochloric acid to salt water is maintained at an absolute pressure of 600 mmHg or less and a saturated vapor pressure of the reaction solution or more in the decomposition tank, and the reaction solution is supplied from the lower part of the decomposition tank to generate an upward flow in the decomposition tank. In this case, chlorate can be decomposed very efficiently. The salt water used is as described above.
【００２１】塩水への塩酸の添加場所、方法、添加量に
ついては、前述の上昇流形式の記載と同じである。タン
ク式であっても構わない。分解槽内は絶対圧６００ｍｍ
Ｈｇ以下、反応液の飽和蒸気圧以上に維持する。このよ
うに分解槽内を減圧とし、かつ上昇流とすることによっ
て塩酸による塩素酸塩の分解効率は著しく良くなる。分
解槽内の絶対圧が６００ｍｍＨｇよりも高い場合、塩酸
による塩素酸塩の分解効果は小さくなり、６００ｍｍＨ
ｇ以下で初めてその効果は顕著となる。一方、分解槽内
の絶対圧が反応液の飽和蒸気圧よりも圧力が低い場合、
水蒸気が多量発生し、不必要な多大な熱エネルギ−を消
費するだけでなく、発生塩素中の水分含量が増すことに
なり、水との分離が必要となり、更に塩素酸塩の分解効
果はそれ程大きくならない。又、水蒸気が生成する時
に、反応液から蒸発熱を奪う為、反応温度の低下がみら
れ、そのため反応速度が遅くなる。従って、分解槽内の
絶対圧を本法の範囲にすることによってのみ、大きな効
果が得られる。なお、上記絶対圧の更に望ましい範囲
は、５００ｍｍＨｇ以下、反応液の飽和蒸気圧よりも１
０ｍｍＨｇ高い圧力以上である。また、反応液の飽和蒸
気圧は、塩水の種類、塩素酸塩濃度、不純物種とその濃
度によって異なるが、これらは適宜求められる値であ
り、例えば温度９０℃の塩化ナトリウム水溶液の場合、
ＮａＣｌ１５０ｇ／リットルで約４７０ｍｍＨｇ、２０
０ｇ／リットルで約４５０ｍｍＨｇ、２５０ｇ／リット
ルで約４２０ｍｍＨｇである。分解槽内の減圧は、真空
ポンプを用いたり、水またはスチ−ムエジェクタ−を用
いることなどにより行なうことができるが、特に温水エ
ジェクタ−を用いれば、エジェクタ−吐出液とガスをタ
ンクに静置させ、液部をエジェクタ−に循環し、ガス部
を回収、脱水して副生高純度塩素ガス又は液化塩素とす
ることができるので好ましい。The location, method, and amount of hydrochloric acid to be added to the salt water are the same as those described above for the upward flow type. It may be a tank type. 600mm absolute pressure in the decomposition tank
Hg or lower and maintained at or above the saturated vapor pressure of the reaction solution. By reducing the pressure in the decomposition tank and increasing the flow, the efficiency of chlorate decomposition by hydrochloric acid is significantly improved. When the absolute pressure in the decomposition tank is higher than 600 mmHg, the effect of decomposing chlorate by hydrochloric acid decreases, and
The effect becomes remarkable only at g or less. On the other hand, when the absolute pressure in the decomposition tank is lower than the saturated vapor pressure of the reaction solution,
A large amount of water vapor is generated, which not only consumes a large amount of unnecessary heat energy, but also increases the water content in the generated chlorine, necessitating the separation from water, and the chlorate decomposition effect is not so high. Does not grow. In addition, when steam is generated, heat of evaporation is removed from the reaction solution, so that the reaction temperature is lowered, and the reaction speed is reduced. Therefore, a great effect can be obtained only by setting the absolute pressure in the decomposition tank within the range of the present method. The absolute pressure is more desirably in a range of 500 mmHg or less, which is not more than the saturated vapor pressure of the reaction solution.
0 mmHg higher pressure or higher. Further, the saturated vapor pressure of the reaction solution varies depending on the type of salt water, chlorate concentration, impurity type and its concentration, and these values are appropriately determined. For example, in the case of a sodium chloride aqueous solution at a temperature of 90 ° C.,
About 470 mmHg at 150 g / liter of NaCl, 20
It is about 450 mmHg at 0 g / liter and about 420 mmHg at 250 g / liter. The pressure in the decomposition tank can be reduced by using a vacuum pump or water or a steam ejector. Particularly, when a hot water ejector is used, the ejected liquid and gas are allowed to stand still in the tank. The liquid portion is preferably circulated to the ejector, and the gas portion is recovered and dehydrated to obtain high-purity by-product chlorine gas or liquefied chlorine.
【００２２】分解槽内の液流れについては、前述の上昇
流についての記述と同一である。The liquid flow in the decomposition tank is the same as that described above for the upward flow.
【００２３】塩素酸塩の分解は、連続式となり生産性、
操作性は向上する。The chlorate is decomposed continuously to improve the productivity,
Operability is improved.
【００２４】又、本発明では、反応液の分解槽内での維
持の条件は特に限定されないが、温度は高い程、短時間
の内に塩水中の塩素酸塩を分解でき、維持時間を長くす
る程、塩素酸塩分解率を大きくできるが、通常、温度７
０〜１００℃程度、維持時間０．１〜３時間程度の条件
であれば十分に塩水中の塩素酸塩を分解し、除去するこ
とができる。In the present invention, the conditions for maintaining the reaction solution in the decomposition tank are not particularly limited. However, the higher the temperature, the more quickly the chlorate in the salt water can be decomposed, and the longer the maintenance time. The chlorate decomposition rate can be increased as the temperature increases.
Under conditions of about 0 to 100 ° C. and a maintenance time of about 0.1 to 3 hours, chlorate in the salt water can be sufficiently decomposed and removed.
【００２５】以上の方法により、塩水中の塩素酸塩を効
率良く、効果的に分解し、除去することができる。また
本発明の方法によれば、塩水の電解の際に塩水中に通常
蓄積する２〜５０ｇ／リットルの塩素酸塩を分解し、通
常要求される１〜３０ｇ／リットルの濃度にまで容易に
低減することができるため、塩水の電解において塩水中
の塩素酸塩の有効な除去手段として用いることができ
る。According to the above method, the chlorate in the salt water can be efficiently and effectively decomposed and removed. Further, according to the method of the present invention, 2 to 50 g / liter of chlorate which normally accumulates in salt water during electrolysis of salt water is decomposed and easily reduced to a normally required concentration of 1 to 30 g / liter. Therefore, it can be used as an effective means for removing chlorate in salt water in electrolysis of salt water.
【００２６】本発明の塩水中の塩素酸塩の除去は、塩水
の電解システムにおいて電解槽から出た戻り塩水が原塩
溶解槽に供給され塩化アルカリで再飽和され電解槽に再
び供給されるラインのどこで行ってもよい。このうち、
特に塩化アルカリで再飽和されて電解槽に供給されるま
でのライン間は、塩水濃度が高くなっており、塩素酸塩
の分解はより容易に進むことから、このライン間で行う
か、または戻り塩水に塩酸を加えて、その一部を電解槽
に循環する系の塩酸を添加する箇所で行うことが好まし
い。前者の場合、添加塩酸量を少なくできるので塩の析
出はほとんどなくなり、また後者の場合、更に塩酸添加
量を少なくでき、また塩水の温度が低下していないため
有利である。更にこれらの場合、塩水の全量を一気に処
理しても塩水の一部を分流し、処理してもよい。In the salt water electrolysis system of the present invention, the chlorate is removed by returning the salt water returned from the electrolytic cell in the salt water electrolysis system to the raw salt dissolving tank, resaturated with alkali chloride, and then re-supplied to the electrolytic cell. You can go anywhere. this house,
In particular, the salt water concentration is high between the lines before being resaturated with alkali chloride and supplied to the electrolytic cell, and the decomposition of chlorate proceeds more easily. It is preferable to add the hydrochloric acid to the salt water and circulate a part of the hydrochloric acid to the electrolytic cell at the point where the hydrochloric acid is added. In the former case, the amount of added hydrochloric acid can be reduced, so that precipitation of salt is almost eliminated. In the latter case, the amount of added hydrochloric acid can be further reduced, and the temperature of the salt water is not lowered, which is advantageous. Further, in these cases, the whole amount of the salt water may be treated at once, or a part of the salt water may be separated and treated.
【００２７】[0027]
【作用】塩素酸塩を含む塩水に塩酸を添加した反応液を
分解槽にて本発明の圧力範囲内に維持することにより塩
素酸塩の除去を効果的、効率的にでき、さらに副生二酸
化塩素を低減できる。その理由は必ずしも明らかではな
いが、塩素酸塩を塩酸で分解すると塩素、二酸化塩素が
生成するが、その中間体として次亜塩素酸塩の生成が推
定され、この場合、次亜塩素酸塩から塩素酸塩を生成す
る逆反応も同時に起こることが考えられる。減圧は塩酸
によりこの次亜塩素酸塩を速やかに塩素ガスに変化させ
る作用をもち、塩素酸塩分解速度が大きくなり、且つ二
酸化塩素の副生を抑制できると推定している。The chlorate can be effectively and efficiently removed by maintaining the reaction solution obtained by adding hydrochloric acid to salt water containing chlorate within the pressure range of the present invention in the decomposition tank. Chlorine can be reduced. Although the reason is not always clear, when chlorate is decomposed with hydrochloric acid, chlorine and chlorine dioxide are generated, but the production of hypochlorite is estimated as an intermediate, in this case, from hypochlorite It is conceivable that the reverse reaction to produce chlorate also occurs at the same time. It is presumed that the reduced pressure has an effect of rapidly changing this hypochlorite into chlorine gas by hydrochloric acid, thereby increasing the chlorate decomposition rate and suppressing the by-product of chlorine dioxide.
【００２８】また、塩素酸塩を含む塩水に塩酸を添加し
た反応液を分解槽内にて上昇流とすることにより塩素酸
塩の除去を効果的、効率的にでき、さらに二酸化塩素の
生成割合を少なくできる。その理由も必ずしも明らかで
はないが、反応液を上昇流とすると、塩素ガスを発生す
る系においても、液の上下混合が抑制され、未分解反応
液のショ−トパスが少なくなる、上昇流と塩素ガスによ
り、塩酸と塩素酸塩の均一混合性が向上し、分解が促進
され、又、二酸化塩素の副生が抑制される。Further, by making the reaction solution obtained by adding hydrochloric acid to salt water containing chlorate ascending in the decomposition tank, chlorate can be effectively and efficiently removed, and the generation rate of chlorine dioxide is further improved. Can be reduced. Although the reason is not necessarily clear, if the reaction liquid is used as an ascending flow, even in a system for generating chlorine gas, up-and-down mixing of the liquid is suppressed and the short path of the undecomposed reaction liquid is reduced. The gas improves the uniform mixing of hydrochloric acid and chlorate, promotes decomposition, and suppresses the by-product of chlorine dioxide.
【００２９】[0029]
【実施例】以下、実施例により本発明を具体的に説明す
るが本発明はこれらに何ら限定されない。EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.
【００３０】なお、本発明において、塩素酸塩の分析は
塩水中にＦｅＳＯ４を過剰に加えた後、これを煮沸し、
残存ＦｅＳＯ４をジフェニルアミンスルホン酸バリウム
を指示薬としてＫ２Ｃｒ２Ｏ７で滴定して行なった。生
成ガス中二酸化塩素は「防災指針II−８」６ペ−ジ、
“分析試験方法”にしたがっておこなった。In the present invention, the chlorate was analyzed by adding an excess amount of FeSO 4 to the salt water and boiling it.
The residual FeSO 4 was performed by titration with K 2 Cr 2 O 7 using barium diphenylamine sulfonate as an indicator. Chlorine dioxide in the generated gas is described in “Disaster Prevention Guideline II-8” on page 6,
The test was performed according to the “analytical test method”.
【００３１】実施例１ 攪拌羽根を備えた円筒型のガラス製３リットル分解槽に
陽イオン交換膜法塩化ナトリウム水溶液電解槽からの戻
り塩水（ＮａＣｌ：２０９ｇ／リットル、ＮａＣｌ
Ｏ３：１０．５ｇ／リットル含む）を５．３リットル／
Ｈｒ、３５％−ＨＣｌを０．７０リットル／Ｈｒの流速
で連続的に別々に供給し、分解槽内の温度を８０℃、攪
拌速度を２００ｒｐｍとし、上記塩水と塩酸との反応液
を均一にした。なお、反応液の飽和蒸気圧は３００ｍｍ
Ｈｇであるため、分解槽内を絶対圧３３０ｍｍＨｇとし
た。その後、一定流量で供給された反応液を連続的に抜
き出し３０分毎に塩素酸ナトリウムの濃度を測定した。
反応を１５時間継続したところ、定常状態での塩素酸ナ
トリウム分解率は７８．３％であった。EXAMPLE 1 Returning brine (NaCl: 209 g / L, NaCl) from a cation exchange membrane method sodium chloride aqueous solution electrolysis tank into a cylindrical glass 3 L decomposition tank equipped with stirring blades
O 3 : 10.5 g / l)
Hr, 35% -HCl are continuously and separately supplied at a flow rate of 0.70 liter / Hr, the temperature in the decomposition tank is set to 80 ° C., and the stirring speed is set to 200 rpm. did. The saturated vapor pressure of the reaction solution was 300 mm
Since the pressure was Hg, the absolute pressure in the decomposition tank was set to 330 mmHg. Thereafter, the reaction solution supplied at a constant flow rate was continuously withdrawn, and the concentration of sodium chlorate was measured every 30 minutes.
When the reaction was continued for 15 hours, the decomposition rate of sodium chlorate in a steady state was 78.3%.
【００３２】比較例１ 分解槽内を常圧とした以外は実施例１と同様の条件で塩
水中の塩素酸ナトリウムの分解を行なった。その結果、
定常状態での塩素酸ナトリウム分解率は６２．９％であ
った。Comparative Example 1 Decomposition of sodium chlorate in salt water was carried out under the same conditions as in Example 1 except that the inside of the decomposition tank was at normal pressure. as a result,
The decomposition rate of sodium chlorate in a steady state was 62.9%.
【００３３】実施例２ 内径４２ｍｍ、高さ２７００ｍｍのジャケット付ガラス
製円筒形分解槽下部より陽イオン交換膜法塩化ナトリウ
ム水溶液電解槽からの戻り塩水（ＮａＣｌ：１９８ｇ／
リットル、ＮａＣｌＯ３：１３．２ｇ／リットルを含
む）を１０．７リットル／Ｈｒ、３５％−ＨＣｌを２．
４１リットル／Ｈｒの流速で連続的に供給し、分解槽内
の温度を８０℃とし、分解槽内は常圧とした。そして一
定量で供給した反応液を、分解槽の液深２４００ｍｍか
ら連続的に抜き出し１５分毎に塩素酸ナトリウムの濃度
を測定した。反応を８時間継続したところ、定常状態で
の塩素酸ナトリウム分解率は７７．５％であった。Example 2 Returning brine (NaCl: 198 g / cm3) from a sodium chloride aqueous solution electrolysis tank by a cation exchange membrane method from the lower part of a jacketed glass cylindrical decomposition tank having an inner diameter of 42 mm and a height of 2700 mm.
10.7 liter / Hr, 35% -HCl (10.7 liter, containing NaClO 3 : 13.2 g / liter).
It was continuously supplied at a flow rate of 41 liter / Hr, the temperature in the decomposition tank was set to 80 ° C., and the pressure in the decomposition tank was set to normal pressure. Then, the reaction solution supplied in a fixed amount was continuously extracted from the liquid depth of 2400 mm in the decomposition tank, and the concentration of sodium chlorate was measured every 15 minutes. When the reaction was continued for 8 hours, the decomposition rate of sodium chlorate in a steady state was 77.5%.
【００３４】実施例３ 分解槽内の圧力を３３０ｍｍＨｇとした以外は実施例２
と同様の条件で塩水中の塩素酸ナトリウムの分解を行な
った。反応が定常状態になったときの分解槽出口での塩
素酸ナトリウムの分解率は８４．９％であった。また、
塩素酸ナトリウム分解により生成したガス中の二酸化塩
素濃度は２容量％以下であり液化塩素として回収でき
た。Example 3 Example 2 except that the pressure in the decomposition tank was set to 330 mmHg.
Decomposition of sodium chlorate in salt water was carried out under the same conditions as described above. When the reaction was in a steady state, the decomposition rate of sodium chlorate at the outlet of the decomposition tank was 84.9%. Also,
The concentration of chlorine dioxide in the gas generated by the decomposition of sodium chlorate was 2% by volume or less and could be recovered as liquefied chlorine.
【００３５】実施例４ 実施例１で用いたものと同様の分解槽に実施例２で用い
た塩水を９．８２リットル／Ｈｒ、３５％−ＨＣｌを
２．１４リットル／Ｈｒの流速で連続的に別々に供給
し、分解槽内の温度を８０℃とした。攪拌速度は２００
ｒｐｍとし、上記塩水と塩酸との反応液を均一にし、分
解槽内は絶対圧３３０ｍｍＨｇとした。その後、一定流
量で供給された反応液を連続的に抜き出し１５分毎に塩
素酸ナトリウムの濃度を測定した。反応を８時間継続し
たところ、定常状態での塩素酸ナトリウム分解率は７
６．２％であった。Example 4 In a decomposition tank similar to that used in Example 1, the salt water used in Example 2 was continuously fed at a flow rate of 9.82 liters / Hr, and 35% HCl was used at a flow rate of 2.14 liters / Hr. And the temperature in the decomposition tank was set to 80 ° C. The stirring speed is 200
rpm, the reaction solution of the above salt water and hydrochloric acid was made uniform, and the absolute pressure in the decomposition tank was set at 330 mmHg. Thereafter, the reaction solution supplied at a constant flow rate was continuously extracted, and the concentration of sodium chlorate was measured every 15 minutes. When the reaction was continued for 8 hours, the decomposition rate of sodium chlorate in the steady state was 7%.
6.2%.
【００３６】比較例２ 分解槽内の圧力を常圧とした以外は実施例４と同様の条
件で塩水中の塩素酸ナトリウムの分解を行なった。反応
が定常状態になったときの塩素酸ナトリウムの分解率は
５５．４％であった。また、塩素酸ナトリウム分解によ
り生成したガス中の二酸化塩素濃度は５．４容量％含ま
れていたため液化塩素として回収できなかった。Comparative Example 2 Decomposition of sodium chlorate in salt water was performed under the same conditions as in Example 4 except that the pressure in the decomposition tank was set to normal pressure. The decomposition rate of sodium chlorate when the reaction was in a steady state was 55.4%. Further, the concentration of chlorine dioxide in the gas generated by the decomposition of sodium chlorate was 5.4% by volume, so that it could not be recovered as liquefied chlorine.
【００３７】比較例３ 塩水に塩酸を添加した反応液を分解槽上部より供給し分
解槽下部より連続的に抜き出したこと以外は実施例２と
同様の条件で塩水中の塩素酸ナトリウムの分解を行なっ
た。その結果、定常状態での塩素酸ナトリウムの分解率
は４９．８％であった。COMPARATIVE EXAMPLE 3 Decomposition of sodium chlorate in salt water was performed under the same conditions as in Example 2 except that a reaction solution obtained by adding hydrochloric acid to salt water was supplied from the upper part of the decomposition tank and continuously extracted from the lower part of the decomposition tank. Done. As a result, the decomposition rate of sodium chlorate in a steady state was 49.8%.
【００３８】実施例５ 実施例２で用いたものと同様の分解槽の下部より陽イオ
ン交換膜法塩化ナトリウム水溶液電解槽からの戻り塩水
（ＮａＣｌ：２０１ｇ／リットル、ＣｌＯ３：１２．１
ｇ／リットルを含む）を２．６４リットル／Ｈｒ、３５
％−ＨＣｌを０．６６リットル／Ｈｒの流速で連続的に
供給し、分解槽内の温度を７０℃とした。なお、反応液
の７０℃における飽和蒸気圧は２００ｍｍＨｇであるた
め、分解槽内の絶対圧は２３０ｍｍＨｇとした。そして
一定量で供給した反応液を連続的に抜き出し１時間毎に
塩素酸ナトリウムの濃度を測定した。反応を１３時間継
続したところ、定常状態での塩素酸ナトリウム分解率は
８２．３％であった。Example 5 Brine (NaCl: 201 g / liter, ClO 3 : 12.1) returned from the lower part of the decomposition tank similar to that used in Example 2 from the electrolytic solution of the sodium chloride aqueous solution using the cation exchange membrane method.
g / liter) to 2.64 liter / Hr, 35
% -HCl was continuously supplied at a flow rate of 0.66 liter / Hr, and the temperature in the decomposition tank was set to 70 ° C. Since the saturated vapor pressure of the reaction solution at 70 ° C. was 200 mmHg, the absolute pressure in the decomposition tank was 230 mmHg. Then, the reaction solution supplied in a fixed amount was continuously extracted, and the concentration of sodium chlorate was measured every hour. When the reaction was continued for 13 hours, the decomposition rate of sodium chlorate in a steady state was 82.3%.
【００３９】比較例４ 実施例１で用いたものと同様の分解槽に実施例５で用い
た塩水を２．４１リットル／Ｈｒ、３５％−ＨＣｌを
０．６０リットル／Ｈｒの流速で連続的に別々に供給
し、分解槽内の温度を７０℃とした。攪拌速度は２００
ｒｐｍとし、上記塩水と塩酸との反応液を均一にし、分
解槽内は絶対圧６５０ｍｍＨｇとした。その後、一定流
量で供給された反応液を連続的に抜き出し１時間毎に塩
素酸ナトリウムの濃度を測定した。反応を１０時間継続
したところ、定常状態での塩素酸ナトリウム分解率は５
１．４％であった。COMPARATIVE EXAMPLE 4 In the same decomposition tank as used in Example 1, the salt water used in Example 5 was continuously fed at a flow rate of 2.41 liter / Hr and 35% -HCl at a flow rate of 0.60 liter / Hr. And the temperature in the decomposition tank was set to 70 ° C. The stirring speed is 200
rpm, the reaction solution of the above salt water and hydrochloric acid was made uniform, and the absolute pressure in the decomposition tank was 650 mmHg. Thereafter, the reaction solution supplied at a constant flow rate was continuously withdrawn, and the concentration of sodium chlorate was measured every hour. When the reaction was continued for 10 hours, the decomposition rate of sodium chlorate in the steady state was 5%.
It was 1.4%.
【００４０】実施例６ 実施例２で用いたものと同様の分解槽の下部より陽イオ
ン交換膜法塩化ナトリウム水溶液電解槽からの戻り塩水
（ＮａＣｌ：２０３ｇ／リットル、ＮａＣｌＯ３：６．
２ｇ／リットルを含む）を２９．９リットル／Ｈｒ、３
５％−ＨＣｌを３．１１リットル／Ｈｒの流速で連続的
に供給し、分解槽内の温度を９０℃とした。なお、反応
液の９０℃における飽和蒸気圧は４５０ｍｍＨｇである
ため、分解槽内の絶対圧は４５０ｍｍＨｇとした。そし
て一定量で供給した反応液を連続的に抜き出し１０分毎
に塩素酸ナトリウムの濃度を測定した。反応を５時間継
続したところ、定常状態での塩素酸ナトリウム分解率は
８３．５％であった。Example 6 Brine (203 g / liter, NaClO 3 : NaClO 3) returned from the electrolytic cell of the sodium chloride aqueous solution by the cation exchange membrane method from the lower part of the decomposition tank similar to that used in Example 2.
29.9 l / hr, 3 g / l
5% -HCl was continuously supplied at a flow rate of 3.11 liter / Hr, and the temperature in the decomposition tank was set to 90 ° C. Since the saturated vapor pressure of the reaction solution at 90 ° C. was 450 mmHg, the absolute pressure in the decomposition tank was 450 mmHg. Then, the reaction solution supplied in a fixed amount was continuously extracted, and the concentration of sodium chlorate was measured every 10 minutes. When the reaction was continued for 5 hours, the decomposition rate of sodium chlorate in a steady state was 83.5%.
【００４１】比較例５ 実施例１で用いたものと同様の分解槽に実施例６で用い
た塩水を２７．２リットル／Ｈｒ、３５％−ＨＣｌを
２．８０リットル／Ｈｒの流速で連続的に別々に供給
し、分解槽内の温度を９０℃とした。攪拌速度は２００
ｒｐｍとし、上記塩水と塩酸との反応液を均一にし、分
解槽内は常圧とした。その後、一定流量で供給された反
応液を連続的に抜き出し１０分毎に塩素酸ナトリウムの
濃度を測定した。反応を４時間継続したところ、定常状
態での塩素酸ナトリウム分解率は５２．４％であった。COMPARATIVE EXAMPLE 5 In a decomposition tank similar to that used in Example 1, the salt water used in Example 6 was continuously used at a flow rate of 27.2 L / Hr, and 35% -HCl was used at a flow rate of 2.80 L / Hr. And the temperature in the decomposition tank was set to 90 ° C. The stirring speed is 200
rpm, the reaction liquid of the above-mentioned salt water and hydrochloric acid was made uniform, and the inside of the decomposition tank was set to normal pressure. Thereafter, the reaction solution supplied at a constant flow rate was continuously extracted, and the concentration of sodium chlorate was measured every 10 minutes. When the reaction was continued for 4 hours, the decomposition rate of sodium chlorate in a steady state was 52.4%.
【００４２】[0042]
【発明の効果】本発明の方法によれば、 （１）反応槽内を減圧にすることにより塩素酸塩の分解
が促進されるため、用いる塩酸の量を少なくすることが
できる。そのため、過剰の塩酸を中和する工程及びアル
カリが必要なくなる。 （２）塩素酸塩の分解は速やかに進行し、装置が簡単で
小型化できる。 （３）反応槽内を減圧にすることにより、塩水中の塩素
ガスの除去も達成できるため塩水電解における塩水の精
製方法のひとつとして本発明を用い、これに引き続いて
後の精製処理を行なうことができる。 （４）塩水電解における循環塩水中の塩素酸塩の蓄積を
防止できる。また本発明によれば塩素酸塩の蓄積防止と
して従来おこなわれていた塩水パ−ジが必要なく完全ク
ロ−ズド化ができる。 （５）塩水電解の製品である苛性アルカリ中の塩素酸塩
濃度を低くでき、製品品質が向上する。 （６）塩素酸塩の分解により塩素及び二酸化塩素ガスが
生成するが、本発明によれば二酸化塩素の生成割合を低
く抑えることができる。そのため生成ガスを液化塩素、
合成塩酸、次亜塩素酸塩等の原料として有効利用でき
る。 などの効果を得ることができる。According to the method of the present invention, (1) Since the decomposition of chlorate is promoted by reducing the pressure in the reaction tank, the amount of hydrochloric acid used can be reduced. Therefore, the step of neutralizing the excess hydrochloric acid and the alkali are not required. (2) The decomposition of chlorate proceeds quickly, and the apparatus can be simplified and downsized. (3) Since the chlorine gas in the salt water can be removed by reducing the pressure in the reaction tank, the present invention is used as one of the methods for purifying the salt water in the salt water electrolysis, and the subsequent purification treatment is performed subsequently. Can be. (4) Accumulation of chlorate in the circulating salt water during salt water electrolysis can be prevented. Further, according to the present invention, complete closure can be achieved without the need for a salt water purge which has been conventionally carried out to prevent the accumulation of chlorate. (5) The chlorate concentration in caustic alkali, which is a product of salt water electrolysis, can be reduced, and the product quality is improved. (6) Chlorine and chlorine dioxide gas are generated by decomposition of chlorate, but according to the present invention, the generation ratio of chlorine dioxide can be kept low. Therefore, the generated gas is liquefied chlorine,
It can be effectively used as a raw material for synthetic hydrochloric acid, hypochlorite and the like. And the like.
【００４３】減圧と上昇流を組み合わせた場合、その効
果は更に大きくなり、極めて効果的、効率的となる。When the depressurization and the upflow are combined, the effect is further enhanced, and it becomes extremely effective and efficient.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) C01D 3/14 C25B 15/08 304 ──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. 7 , DB name) C01D 3/14 C25B 15/08 304
Claims (1)
に供する塩化アルカリ水溶液に塩酸を添加した反応液
を、分解槽にて絶対圧６００ｍｍＨｇ以下、反応液の飽
和蒸気圧以上に維持し、及び／又は反応液を分解槽下部
より供給し分解槽内を上昇流とすることを特徴とする塩
化アルカリ水溶液中の塩素酸塩の除去方法。A reaction solution obtained by adding hydrochloric acid to an alkali chloride aqueous solution to be subjected to electrolysis of an alkali chloride aqueous solution by a cation exchange membrane method is maintained in a decomposition tank at an absolute pressure of 600 mmHg or less and a saturated vapor pressure of the reaction solution or more, and / or Alternatively, a method for removing chlorate from an aqueous alkali chloride solution, wherein the reaction solution is supplied from a lower portion of the decomposition tank and the inside of the decomposition tank is made to flow upward.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE69118120T DE69118120T2 (en) | 1990-11-28 | 1991-11-27 | Process for the removal of chlorate from an aqueous sodium chloride solution |
| EP91120323A EP0488251B1 (en) | 1990-11-28 | 1991-11-27 | Process for removing chlorate salt from aqueous alkali chloride solution |
| US07/798,715 US5279717A (en) | 1990-11-28 | 1991-11-29 | Process for removing chlorate salt from aqueous alkali chloride solution |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2-322353 | 1990-11-28 | ||
| JP32235390 | 1990-11-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH054814A JPH054814A (en) | 1993-01-14 |
| JP3097241B2 true JP3097241B2 (en) | 2000-10-10 |
Family
ID=18142698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03322413A Expired - Fee Related JP3097241B2 (en) | 1990-11-28 | 1991-11-12 | Method for removing chlorate from aqueous alkali chloride solution |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3097241B2 (en) |
| CA (1) | CA2056243A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4792631B2 (en) * | 2000-10-31 | 2011-10-12 | 東ソー株式会社 | Method for removing chlorate from aqueous alkali chloride solution |
-
1991
- 1991-11-12 JP JP03322413A patent/JP3097241B2/en not_active Expired - Fee Related
- 1991-11-26 CA CA 2056243 patent/CA2056243A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| CA2056243A1 (en) | 1992-05-29 |
| JPH054814A (en) | 1993-01-14 |
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