JPH09271785A - Treatment of fluorine containing waste water - Google Patents
Treatment of fluorine containing waste waterInfo
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- JPH09271785A JPH09271785A JP8514996A JP8514996A JPH09271785A JP H09271785 A JPH09271785 A JP H09271785A JP 8514996 A JP8514996 A JP 8514996A JP 8514996 A JP8514996 A JP 8514996A JP H09271785 A JPH09271785 A JP H09271785A
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- fluorine
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体や液晶等の
電子製品ないしはその素子の製造プロセスから排出され
るフッ素含有排水や、その他の産業におけるフッ素含有
排水の処理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 a fluorine-containing wastewater discharged from a manufacturing process of electronic products such as semiconductors and liquid crystals or elements thereof, and a method for treating fluorine-containing wastewater in other industries.
【０００２】[0002]
【従来の技術】半導体の製造においては、大量の薬液と
超純水を使用するウエット・プロセスがある。現在、ウ
エット・プロセスからの排水処理で最も大きな負担とな
っているのは、フッ素化合物を含む排水である。2. Description of the Related Art In semiconductor manufacturing, there is a wet process using a large amount of chemical liquid and ultrapure water. Currently, the largest burden of wastewater treatment from the wet process is wastewater containing fluorine compounds.
【０００３】図６に、従来のフッ素含有排水の処理シス
テムのフローシートを示す。この処理方法では、まず、
フッ素化合物含有排水（フッ素イオン：１００ｍｇ／ｌ
以上）に中和剤として消石灰を添加して一次処理を行
い、反応式Ｃａ2+＋２Ｆ- →ＣａＦ2 に従ってＣａＦ2
を沈殿せしめ、これを含む前段スラッジを除去する。つ
いで、一次処理水（フッ素イオン：約２０ｍｇ／ｌ）に
凝集剤として硫酸アルミニウムを添加して高度処理を行
い、反応式Ａｌ3+＋３ＯＨ→Ａｌ（ＯＨ）3 に従って生
成したフッ素吸着性のＡｌ（ＯＨ）3 にフッ素を吸着せ
しめて沈殿させ、このＡｌ（ＯＨ）3 を含む後段スラッ
ジを除去する。高度処理水（フッ素イオン：１〜１０ｍ
ｇ／ｌ）を系外へ放流する。FIG. 6 shows a flow sheet of a conventional treatment system for fluorine-containing wastewater. In this processing method, first,
Wastewater containing fluorine compound (fluoride ion: 100 mg / l
Performs primary processing by adding slaked lime as a neutralizing agent to the above), Scheme Ca 2+ + 2F - → CaF 2 according CaF 2
And to remove the pre-stage sludge containing this. Then, aluminum sulfate as a flocculant is added to the primary treated water (fluorine ion: about 20 mg / l) to perform advanced treatment, and fluorine-adsorbing Al () produced according to the reaction formula Al 3+ + 3OH → Al (OH) 3 is added. OH) 3 is adsorbed with fluorine to cause precipitation, and the latter stage sludge containing this Al (OH) 3 is removed. Advanced treated water (fluorine ion: 1-10m
g / l) is discharged out of the system.
【０００４】このプロセスで用いられる消石灰は微粒子
であり、水に溶解して液相反応によりＣａＦ2 微粒子を
生成する。これを分離するには、上記のような凝集剤の
添加やシックナー等の設備が必要であり、スラッジの含
水率はフィルタープレスによる脱水後でも約８０％であ
る。スラッジ中のＣａＦ2 含有率は通常１０％以下であ
る。The slaked lime used in this process is fine particles and dissolves in water to produce CaF 2 fine particles by a liquid phase reaction. In order to separate this, it is necessary to add the above-mentioned coagulant and equipment such as thickener, and the water content of sludge is about 80% even after dehydration by a filter press. The CaF 2 content in the sludge is usually 10% or less.
【０００５】そのため、このような排水を処理して、処
理水中のフッ素濃度を排水規制値以下とするためには、
中和剤として消石灰や凝集剤として硫酸アルミニウム、
高分子凝集剤等が過剰量用いられ、その結果大量のスラ
ッジが発生し、廃棄物となっている。Therefore, in order to treat such wastewater so that the concentration of fluorine in the treated water becomes equal to or lower than the wastewater regulation value,
Slaked lime as a neutralizer and aluminum sulfate as a flocculant,
An excessive amount of polymer flocculant is used, and as a result, a large amount of sludge is generated and becomes waste.
【０００６】例えば、ＨＦ５０％のフッ化水素酸換算で
１トンのフッ化水素酸から発生するスラッジの量は、通
常１０トンを越えるものとなり、大量の廃棄物を生じる
こととなる。For example, the amount of sludge generated from 1 ton of hydrofluoric acid in terms of HF50% hydrofluoric acid usually exceeds 10 ton, and a large amount of waste is generated.
【０００７】処理水の水質も、排水規制値をクリアする
ものではあるが、再利用に適したものではない。The quality of the treated water also meets the wastewater regulation value, but is not suitable for reuse.
【０００８】[0008]
【発明が解決しようとする課題】従来の方法における問
題点として下記の点がある。The problems in the conventional method are as follows.
【０００９】原排水中に存在するフッ素の量に対し
て、廃棄物として生成するスラッジの量が非常に大量と
なる。The amount of sludge produced as a waste becomes very large relative to the amount of fluorine present in the raw waste water.
【００１０】凝集剤を多量に使用しても、処理水の水
質が再利用に適するほど良好にならない。Even if a large amount of the flocculant is used, the quality of the treated water is not good enough for reuse.
【００１１】凝集槽、シックナー、沈降ポンドなど、
敷地面積の大きな諸設備が必要である。Coagulating tanks, thickeners, sedimentation ponds, etc.
Various equipment with a large site area is required.
【００１２】本発明の目的は、このような問題点を克服
することができるフッ素含有排水の処理方法を提供する
ことにある。An object of the present invention is to provide a method for treating fluorine-containing wastewater which can overcome such problems.
【００１３】[0013]
【課題を解決するための手段】本発明は、フッ素含有排
水を蒸発濃縮して、廃液量を減少させると同時に大部分
の水を蒸留水として回収する方法であって、蒸発濃縮の
前に上記排水にアルカリ性水溶液を添加することによっ
て水の蒸発に伴うフッ化水素酸の気化を最小限に抑える
ことを特徴とするフッ素含有排水の処理方法である。The present invention is a method for evaporating and concentrating fluorine-containing wastewater to reduce the amount of waste liquid and at the same time recover most of the water as distilled water. A method for treating fluorine-containing wastewater, characterized in that vaporization of hydrofluoric acid accompanying evaporation of water is minimized by adding an alkaline aqueous solution to the wastewater.
【００１４】本発明の好適な実施形態においては、アル
カリ性水溶液として苛性ソーダ水溶液を使用し、蒸発濃
縮装置出口における最終濃縮水のｐＨを６から８．５、
望ましくは６．２から７．５の範囲となるよう苛性ソー
ダの添加量を調整し、蒸発濃縮装置出口の最終濃縮水中
のＮａＦ濃度を３．６重量％以下に制御して、フッ素濃
度３．３ｐｐｍ以下、望ましくは１ｐｐｍ以下の蒸留水
を回収する。In a preferred embodiment of the present invention, a caustic soda aqueous solution is used as the alkaline aqueous solution, and the pH of the final concentrated water at the outlet of the evaporative concentration apparatus is 6 to 8.5.
Desirably, the amount of caustic soda added is adjusted to be in the range of 6.2 to 7.5, the NaF concentration in the final concentrated water at the outlet of the evaporative concentration device is controlled to be 3.6% by weight or less, and the fluorine concentration is 3.3 ppm. Hereafter, preferably 1 ppm or less of distilled water is recovered.
【００１５】本発明の今１つの好適な実施形態において
は、アルカリ性水溶液として苛性カリ水溶液を使用し、
蒸発濃縮装置出口の最終濃縮水のｐＨを６から８．５、
望ましくは６．２から７．３の範囲となるよう添加する
苛性カリ量を調整し、蒸発濃縮装置出口の最終濃縮水中
のＫＦ濃度を１０重量％以下に制御して、フッ素濃度
６．５ｐｐｍ以下、望ましくは２ｐｐｍ以下の蒸留水を
回収する。In another preferred embodiment of the invention, an aqueous caustic potash solution is used as the alkaline aqueous solution,
The pH of the final concentrated water at the outlet of the evaporative concentrator is 6 to 8.5,
Desirably, the amount of caustic potassium added is adjusted so as to fall within the range of 6.2 to 7.3, the KF concentration in the final concentrated water at the outlet of the evaporative concentration device is controlled to 10% by weight or less, and the fluorine concentration is 6.5 ppm or less, Desirably, 2 ppm or less of distilled water is recovered.
【００１６】排水を減容し同時に清浄水を回収する方法
として、蒸発濃縮法がある。There is an evaporative concentration method as a method for reducing the volume of waste water and at the same time collecting clean water.
【００１７】本発明は、蒸発濃縮法をフッ素含有排水の
処理に適用して、上記課題を解決せんとするものであ
る。The present invention intends to solve the above problems by applying the evaporative concentration method to the treatment of fluorine-containing wastewater.
【００１８】フッ素を含有する排水は、通常酸性の状態
で排出される。これをそのまま蒸発濃縮したのでは、水
の蒸発と並行してフッ化水素酸の気化が生じ、凝縮生産
水中に再溶解してくる上に、装置構成材料の腐食が甚し
く、実用に耐える経済的な材料の選定が困難である。Waste water containing fluorine is usually discharged in an acidic state. If this is evaporated and concentrated as it is, the hydrofluoric acid will be vaporized in parallel with the evaporation of water, and will be redissolved in the condensed production water, and the equipment constituent materials will be severely corroded, making it an economical solution that can be put to practical use. It is difficult to select a suitable material.
【００１９】したがって、アルカリ性物質の添加によっ
て原排水の中和を行う必要があるが、これを消石灰によ
って中和を行ったのでは、反応生成物としてのフッ化カ
ルシウム微粒子や未反応の消石灰微粒子を含むスラリー
液を濃縮することになり、蒸発濃縮装置内の伝熱面にス
ケールが付着して、装置の効率の低下を持たらし、甚し
くは装置の安定な運転を阻害する。Therefore, it is necessary to neutralize the raw waste water by adding an alkaline substance, but if this is neutralized with slaked lime, calcium fluoride fine particles as reaction products and unreacted slaked lime fine particles are removed. As a result, the contained slurry liquid is concentrated, and the scale adheres to the heat transfer surface in the evaporative concentrator, which causes a decrease in the efficiency of the apparatus, and seriously hinders stable operation of the apparatus.
【００２０】本発明は、これらの問題点を解決するため
の手段を与えるが、その説明のために、フッ化水素とそ
の水溶液としてのフッ化水素酸との間の平衡についてま
ず検討を行う。The present invention provides a means for solving these problems, but for the purpose of explanation, the equilibrium between hydrogen fluoride and hydrofluoric acid as its aqueous solution will be first examined.
【００２１】希薄フッ化水素酸の蒸発濃縮を行うために
その水分を蒸発させると、同時にフッ化水素も蒸発して
くる。これは、希薄フッ化水素酸中に未解離のフッ化水
素が存在し、その状態に平衡な気相分圧を有するからで
ある。フッ化水素酸中のフッ素の存在形態については後
述するが、ＨＦ、Ｆ- 、ＨＦ2 - の全てがＨＦ形態にあ
ると見なして濃度表示した時の気液平衡関係のデータが
知られている（Ｖ．Ｂ．コーガン編、平田光穂訳、「気
液平衡データブック」、株式会社講談社より昭和４９年
５月１０日発行、２０６〜２０７ページ）。図１は、温
度（または圧力）をパラメータとして上記データを図示
したものである。When the water content of the dilute hydrofluoric acid is evaporated, the hydrogen fluoride is also evaporated. This is because undissociated hydrogen fluoride exists in the dilute hydrofluoric acid, and the gas phase partial pressure is in equilibrium in that state. The existence form of fluorine in hydrofluoric acid will be described later, but it is known that the gas-liquid equilibrium relationship data is obtained when the concentration is displayed by assuming that all of HF, F − , and HF 2 − are in the HF form. (V. B. Corgan edited by Mitsuho Hirata, "Vapor-Liquid Equilibrium Data Book", published by Kodansha, Ltd. on May 10, 1974, pages 206-207). FIG. 1 illustrates the above data using temperature (or pressure) as a parameter.
【００２２】希薄フッ化水素酸の蒸発濃縮をこのままで
行うと、液相内ＨＦ濃度の上昇と共に蒸発蒸気中のＨＦ
濃度も上昇し、その蒸気を冷却濃縮させて得られる蒸留
水中のＨＦも高濃度で、ＨＦの分離除去をなし得ない。
したがって、液相の状態を改善して、気相内ＨＦを大幅
に低減する必要がある。When the dilute hydrofluoric acid is evaporated and concentrated as it is, the HF concentration in the liquid phase increases and the HF in the evaporated vapor increases.
The concentration also rises, and the HF in distilled water obtained by cooling and condensing the vapor is also high in concentration, and HF cannot be separated and removed.
Therefore, it is necessary to improve the state of the liquid phase and significantly reduce the HF in the gas phase.
【００２３】ところで、純水に溶解したフッ化水素の解
離は次のように行なわれることが知られている（千谷利
三著、「新版無機化学（下巻）」、第１０刷、産業図書
株式会社より昭和４３年６月５日発行、１１０１〜１１
０２ページ）。By the way, it is known that dissociation of hydrogen fluoride dissolved in pure water is carried out as follows (Rishou Chitani, "New Edition Inorganic Chemistry (2nd Volume)", 10th edition, Industrial Books. Published on June 5, 1968 by a corporation, 1101-11
Page 02).
【００２４】[0024]
【式１】 (Equation 1)
【００２５】しかしこの解離によって生じたフッ素イオ
ンは、未解離のフッ化水素分子と次のように結合する。However, the fluorine ions generated by this dissociation are combined with the undissociated hydrogen fluoride molecules as follows.
【００２６】[0026]
【式２】 (Equation 2)
【００２７】さらに、これらの両反応の平衡定数は、次
式で示される（但し温度は２５℃）。Further, the equilibrium constant of both these reactions is shown by the following equation (however, the temperature is 25 ° C.).
【００２８】[0028]
【式３】 (Equation 3)
【００２９】上記式(3) と式(4) 、および水の解離平衡
の関係、フッ素イオンの収支、溶液の電気的中性の関係
を使えば、純水に一定量のＨＦが溶解した時の、水中で
の各形態の物質の存在量とｐＨを計算することができ
る。本発明者が実施した計算の結果を、図２に示す。図
２の横軸は溶解させたＨＦの全量をモル分率で示してお
り（ＨＦ、Ｆ- 、ＨＦ2 - の全てがＨＦの状態にあると
仮定している）、左側の縦軸は実際に未解離の状態にあ
るものの計算値をモル分率で示している。この計算結果
から、全ＨＦ濃度（モル分率）が０．０１〜０．５の範
囲にあっては、８９．２％〜９４．３％が未解離のＨＦ
の状態であることが判る。また右側の縦軸はｐＨの計算
値を示している。Using the above equations (3) and (4), the relation of dissociation equilibrium of water, the balance of fluorine ions, and the electrical neutrality of the solution, when a certain amount of HF is dissolved in pure water. The abundance and pH of each form of substance in water can be calculated. The result of the calculation performed by the present inventor is shown in FIG. The horizontal axis of FIG. 2 shows the total amount of dissolved HF in mole fractions (assuming that all of HF, F − and HF 2 − are in the HF state), and the vertical axis on the left side is actually The calculated values for the undissociated state are shown in mole fractions. From this calculation result, when the total HF concentration (molar fraction) is in the range of 0.01 to 0.5, 89.2% to 94.3% is undissociated HF.
It is understood that it is in the state of. The vertical axis on the right side shows the calculated value of pH.
【００３０】このように未解離のＨＦが多く存在するこ
とによって、この液体と平衡な気体中のＨＦ分圧が大き
くなる傾向が出てきている。Due to the presence of a large amount of undissociated HF, the HF partial pressure in the gas in equilibrium with the liquid tends to increase.
【００３１】希薄な液相濃度範囲にあっては、未解離Ｈ
Ｆの液相濃度ｘHFと気相濃度ｙHFは比例関係 ｙHF＝ｍ
・ｘHF（ヘンリーの法則、ｍはヘンリー定数）が成立す
るが、図１の濃度範囲においては、特に２５℃のデータ
は高濃度範囲のものしかなく、ヘンリーの法則の適用さ
れる範囲を外れている。正確には、高濃度では、活量係
数を考慮する必要があるが、平衡な気相ＨＦ濃度ｙHFを
下げるためには、液相内の解離状態を大幅に修正して、
未解離のＨＦ濃度ｘHFを大幅に小さくする必要があるこ
とがよく理解される。In the diluted liquid phase concentration range, undissociated H
Liquid phase concentration x HF of F and gas phase concentration y HF are proportional to each other y HF = m
・ X HF (Henry's law, m is Henry's constant) holds, but in the concentration range of Fig. 1, the data at 25 ° C is only in the high concentration range, which is outside the range to which Henry's law applies. ing. To be precise, at a high concentration, it is necessary to consider the activity coefficient, but in order to lower the equilibrium gas phase HF concentration y HF , the dissociation state in the liquid phase should be significantly modified,
It is well understood that the undissociated HF concentration x HF needs to be significantly reduced.
【００３２】図１の気液平衡データの内２５℃における
最も低濃度の点は、全ＨＦ濃度として、０．１７４２の
点である。上記の計算結果から、この濃度において未解
離ＨＦは全ＨＦの９１％であり、すなわち未解離のＨＦ
濃度ｘHF＝０．１５８５であり、ｙHF＝０．０３４３か
ら、ｍ＝ｙHF／ｘHF＝０．１２６４を得る。上述したよ
うに、このデータはヘンリーの法則が適用される範囲を
外れた濃度範囲のものであるが、低濃度範囲へこの値を
適用することは安全サイドにあるので、後述の検討でこ
の値を使用する。The lowest concentration point at 25 ° C. in the vapor-liquid equilibrium data of FIG. 1 is 0.1742 as the total HF concentration. From the above calculation results, undissociated HF was 91% of total HF at this concentration, that is, undissociated HF
From the concentration x HF = 0.1585 and y HF = 0.0343, we obtain m = y HF / x HF = 0.1264. As mentioned above, this data is in the concentration range outside the range where Henry's law is applied, but it is on the safety side to apply this value to the low concentration range, so this value will be examined in the later discussion. To use.
【００３３】また、(1) 式からも明らかなように、ＨＦ
の解離を進めるためには、Ｈ+ 濃度を下げることが有効
である。Ｈ+ 濃度は、アルカリ性物質を添加して中和す
ることにより容易に下げられるが、経済性を高めるため
には、蒸発濃縮により回収する水の純度に関して必要な
レベルの範囲で添加量を最小にする必要がある。Further, as is clear from the equation (1), HF
In order to promote the dissociation of H + , it is effective to reduce the H + concentration. The H + concentration can be easily lowered by adding an alkaline substance to neutralize it, but in order to increase the economic efficiency, the addition amount should be minimized within the range of the level required for the purity of water recovered by evaporative concentration. There is a need to.
【００３４】アルカリを添加してｐＨを変化させた場合
のＨＦの解離の計算は、上述の計算と同様にできるが、
水の解離平衡の関係を与える変わりに、Ｈ+ 濃度を直接
与えればよい。このようにして計算した、ｐＨを変化さ
せた時の液相全ＨＦ濃度と未解離ＨＦ濃度の関係を、図
３に示す。ｐＨを６〜９に調整することにより、同一の
全ＨＦ濃度における未解離ＨＦ濃度は、およそ１／６０
０〜１／６０００００と大幅に小さくなる。The calculation of dissociation of HF when the pH is changed by adding an alkali can be performed in the same manner as the above calculation.
Instead of giving the relation of water dissociation equilibrium, the H + concentration may be given directly. The relationship between the liquid phase total HF concentration and the undissociated HF concentration when the pH is changed, calculated in this way, is shown in FIG. By adjusting the pH to 6-9, the undissociated HF concentration at the same total HF concentration was about 1/60
It is significantly reduced to 0 to 1/600000.
【００３５】一方、ｐＨを調整するために添加するアル
カリ物質については、経済性の面から低廉であることと
同時に、中和によって生成する塩の溶解度が大であるこ
とが重要である。これらの点から、ｐＨを添加するアル
カリ物質としては、ＮａＯＨあるいはＫＯＨが最適であ
る。これらの最適な添加量については、実施例により説
明する。On the other hand, it is important that the alkaline substance added to adjust the pH is inexpensive from the economical viewpoint, and at the same time, the solubility of the salt produced by neutralization is high. From these points, NaOH or KOH is most suitable as the alkaline substance to which the pH is added. The optimum addition amount of these will be described with reference to examples.
【００３６】[0036]
実施例１ 図４において、フッ素含有排水は、Ｆとして１００ｐｐ
ｍのフッ素分を含み、処理量は１０ｔｏｎ／ｈである。
この排水にアルカリ性水溶液として苛性ソーダ水溶液を
添加し、ついでこの排水を蒸発濃縮した。この濃縮によ
って、濃縮水量を大幅に減少させると同時に大部分の水
を蒸留水として回収した。また、苛性ソーダ水溶液の添
加によって水の蒸発に伴うフッ酸の気化が最小限に抑え
られる。Example 1 In FIG. 4, the fluorine-containing wastewater is 100 pp as F.
Fluorine content of m is included, and the throughput is 10 ton / h.
An aqueous caustic soda solution was added as an alkaline aqueous solution to the waste water, and then the waste water was evaporated and concentrated. By this concentration, the amount of concentrated water was significantly reduced, and at the same time, most of the water was recovered as distilled water. Further, the addition of the caustic soda aqueous solution minimizes the vaporization of hydrofluoric acid accompanying the evaporation of water.
【００３７】この実施例では、中和のために苛性ソーダ
水溶液を使用している。中和された排水を蒸発濃縮装置
で過度に濃縮すると、ＮａＦとしての溶解度を越えたと
ころでＮａＦの析出が生じるので、装置の効率が低下
し、安定な運転が不可能となる。苛性ソーダ水溶液の添
加量は、蒸発濃縮装置から出た濃縮水のｐＨをセンサー
で検知し、この検知信号によってアルカリ性水溶液注入
装置を可動させることによって制御される。In this embodiment, an aqueous solution of caustic soda is used for neutralization. If the neutralized wastewater is excessively concentrated by an evaporative concentrator, NaF will be deposited when the solubility as NaF is exceeded, so that the efficiency of the apparatus is lowered and stable operation becomes impossible. The amount of the caustic soda aqueous solution added is controlled by detecting the pH of the concentrated water discharged from the evaporative concentrator with a sensor and moving the alkaline aqueous solution injector by the detection signal.
【００３８】（財団法人日本化学会編、「化学便覧基礎
編改訂３版」、丸善株式会社より昭和５９年６月２５日
発行、Ｐ．II−１６６〜II-173ページ）によれば、Ｎａ
Ｆの２５℃における溶解度は３．９８重量％である。し
たがって、運転の多少の変動も考慮して、蒸発濃縮器に
おける濃縮最終濃度を、飽和溶解度の約９０％である
３．６％に設定した。蒸発濃縮装置における濃縮水の温
度は２５℃より高く、溶解度は温度が高くなるに従って
多少大きくなるが、安全サイドの基準として２５℃の溶
解度を採った。According to "The Chemical Society of Japan," Chemical Handbook Basic 3rd Revised Edition ", Maruzen Co., Ltd., June 25, 1984, pp. II-166-II-173),
The solubility of F at 25 ° C is 3.98% by weight. Therefore, the final concentration of concentration in the evaporative concentrator was set to 3.6%, which is about 90% of the saturation solubility, taking into account some fluctuations in the operation. The temperature of the concentrated water in the evaporative concentrator was higher than 25 ° C, and the solubility increased a little as the temperature increased, but the solubility of 25 ° C was adopted as a safety standard.
【００３９】蒸発濃縮装置で回収される蒸留水の純度
は、水の蒸発と並行して気化し水蒸気の凝縮時に凝縮水
（蒸留水）に再溶解する成分の量と共に、蒸発面から凝
縮面に移行する水蒸気に同伴される濃縮水滴の量に左右
される。高純度の凝縮水（蒸留水）が必要な場合には、
蒸発濃縮装置の計画に当たって、飛沫同伴を最小にでき
る機種を選定することと、最適な気水分離器の設計が重
要である。The purity of the distilled water recovered by the evaporative concentrator is determined from the evaporation surface to the condensation surface together with the amount of the components that are vaporized in parallel with the evaporation of water and redissolved in the condensed water (distilled water) when the water vapor is condensed. It depends on the amount of concentrated water droplets entrained in the migrating water vapor. If you need high-purity condensed water (distilled water),
When planning an evaporative concentrator, it is important to select a model that can minimize entrainment of droplets and to design an optimal steam-water separator.
【００４０】蒸発濃縮装置の技術分野では、気水分離性
能の目安として、次式で定義される除染係数が使用され
る。In the technical field of evaporative concentration equipment, the decontamination coefficient defined by the following equation is used as a measure of the water-water separation performance.
【００４１】[0041]
【式４】 (Equation 4)
【００４２】最新の技術を駆使した蒸発濃縮装置では、
除染係数を１０4 〜１０5 程度にすることが可能であ
る。In the evaporative concentrator using the latest technology,
The decontamination coefficient can be set to about 10 4 to 10 5 .
【００４３】また、不純物の気化がなく飛沫同伴によっ
てのみ蒸留水の純度が決まる場合には、概ね次式の関係
がある。Further, when the purity of distilled water is determined only by entrainment of droplets without vaporization of impurities, there is a relation of the following formula.
【００４４】[0044]
【式５】 (Equation 5)
【００４５】この関係から、飛沫同伴によって蒸留水中
に持ち込まれる不純物濃度を求めることができる。(6)
式は、厳密には装置内での平均の濃縮水濃度で考えられ
るべきであるが、ここでは、安全サイドの目安として、
最終濃縮水の塩濃度で計算する。From this relationship, the concentration of impurities brought into the distilled water due to the entrainment of droplets can be obtained. (6)
The formula should be considered strictly as the average concentration of concentrated water in the device, but here, as a measure on the safety side,
Calculated as the salt concentration of the final concentrated water.
【００４６】本実施例の場合、最終濃縮水の濃度は３．
６重量％（全フッ素成分のモル分率としては、０．０１
５２）に設定されたので、飛沫同伴によって蒸留水中に
持ち込まれる不純物濃度は、ＮａＦとして３．６〜０．
３６ｐｐｍ（Ｆとして１．６〜０．１６ｐｐｍ）とな
る。In the case of this embodiment, the concentration of the final concentrated water is 3.
6% by weight (0.01 mol% of total fluorine component
52), the concentration of impurities brought into distilled water by entrainment of droplets is 3.6 to 0.
It becomes 36 ppm (1.6 to 0.16 ppm as F).
【００４７】これを、フッ素成分のモル分率として表せ
ば、１．５４×１０-6〜１．５４×１０-7となる。When expressed as the mole fraction of the fluorine component, it is 1.54 × 10 −6 to 1.54 × 10 −7 .
【００４８】次に、水の蒸発に伴ってＨＦとして気化し
蒸留水に再溶解する不純物量をどの程度に抑えるべきか
という問題を考える。蒸発濃縮装置では飛沫同伴によっ
て上記のオーダーの不純物が蒸留水中に持ち込まれるこ
とは、経済的な制約の範囲では避けられないので、いた
ずらにｐＨを高くして気化ＨＦを少なくしても、蒸留水
の純度を高める効果には限界がある。経済性を考慮した
実際的な方法としては、飛沫同伴によって持ち込まれる
フッ素量と気化・再溶解によって持ち込まれるフッ素量
とをほぼ同レベルにするのが妥当である。Next, let us consider the problem of how much the amount of impurities vaporized as HF as water evaporates and redissolved in distilled water should be suppressed. It is unavoidable that impurities of the above order are brought into distilled water by entrainment in the evaporative concentrator due to entrainment, so that even if the pH is unnecessarily increased and vaporized HF is reduced, distilled water is There is a limit to the effect of increasing the purity of. As a practical method in consideration of economic efficiency, it is appropriate to make the amount of fluorine brought in by the entrained droplets and the amount of fluorine brought in by vaporization / redissolution almost at the same level.
【００４９】すなわち、濃縮水から蒸発する蒸気中のＨ
Ｆ濃度ｙHFが１．５４×１０-6〜１．５４×１０-7以
下、実際的には種々の計算誤差を勘案して範囲を拡大す
る必要から、２×１０-6〜９×１０-8となるように、液
相の未解離ＨＦ濃度を下げなければならない。上述した
ヘンリー定数ｍ＝０．１２６４を使用して、対応する未
解離のＨＦの濃度ｘHFを定めると、必要なｘHFの範囲
は、１．５×１０-5〜７×１０-7となる。That is, H in the vapor evaporated from the concentrated water
F concentration y HF is 1.54 × 10 −6 to 1.54 × 10 −7 or less, and in practice it is necessary to expand the range in consideration of various calculation errors, so that it is 2 × 10 −6 to 9 × 10. The undissociated HF concentration in the liquid phase must be reduced so that it becomes -8 . When the corresponding undissociated HF concentration x HF is determined using the Henry constant m = 0.1264 described above, the required range of x HF is 1.5 × 10 −5 to 7 × 10 −7 . Become.
【００５０】最終濃縮水の全ＨＦ濃度＝０．０１５２
（モル分率）において、未解離のＨＦ濃度をこの範囲に
収めるために必要なｐＨを図３から求めれば、６．２＜
ｐＨ＜７．５の範囲が定まる。このようにすることによ
って、飛沫同伴で持ち込まれる量と同量のフッ素成分
が、気化したＨＦの再溶解として、蒸留水中に持ち込ま
れる。Total HF concentration of final concentrated water = 0.0152
In (molar fraction), the pH required to keep the undissociated HF concentration within this range was calculated from FIG.
The range of pH <7.5 is determined. By doing so, the same amount of fluorine component as that brought in by entrainment is brought into the distilled water as redissolution of vaporized HF.
【００５１】以上の説明から明らかなように、Ｆとして
１００ｐｐｍのフッ素成分を含む排水１０ｔｏｎ／ｈ
を、濃縮水のｐＨ６．２〜７．５になるようにフッ素含
有排水に苛性ソーダを添加して蒸発濃縮装置に供給し、
最終濃縮水中のＮａＦ塩濃度を３．６重量％に保って処
理したところ、蒸留水として９．９３ｔｏｎ／ｈの純水
が回収され（回収率９９．３％）、回収水中のフッ素濃
度は、ＮａＦとして０．７２〜７．２ｐｐｍ（Ｆとして
０．３３〜３．３ｐｐｍ）であった。As is clear from the above description, wastewater containing 100 ppm of fluorine as F is 10 ton / h.
Is added to the evaporative concentrator by adding caustic soda to the fluorine-containing wastewater so that the pH of the concentrated water becomes 6.2 to 7.5.
When the NaF salt concentration in the final concentrated water was maintained at 3.6% by weight, pure water of 9.93 ton / h was recovered as distilled water (recovery rate 99.3%), and the fluorine concentration in the recovered water was It was 0.72-7.2 ppm as NaF (0.33-3.3 ppm as F).
【００５２】このように、本発明方法によって、回収水
中の、ＮａＦ以外の不純物（有機物、無機物共に）は極
めて少なく、プロセス純水とて再利用するためのイオン
交換または逆浸透装置の負荷は非常に小さくなった。As described above, according to the method of the present invention, impurities other than NaF (both organic substances and inorganic substances) in the recovered water are extremely small, and the load of the ion exchange or reverse osmosis device for reuse as process pure water is extremely low. Became smaller.
【００５３】また、濃縮水量６１．４ｋｇ／ｈであっ
て、フッ素含有排水量の約１／１６３となり、後処理が
非常に経済的になった。Further, the amount of concentrated water was 61.4 kg / h, which was about 1/163 of the amount of waste water containing fluorine, and the post-treatment became very economical.
【００５４】濃縮水のフッ素濃度が高くなっているた
め、濃縮水の後処理は容易である。濃縮水の後処理は、
上述した従来技術（図６参照）において、化学当量の消
石灰を添加することによって、極めて効率的に実施でき
る。Since the concentration of fluorine in the concentrated water is high, the post-treatment of the concentrated water is easy. The post-treatment of concentrated water is
In the above-mentioned conventional technique (see FIG. 6), it can be carried out extremely efficiently by adding a chemical equivalent of slaked lime.
【００５５】この際上澄み液として、苛性ソーダ水溶液
を回収することもできる。At this time, a caustic soda aqueous solution may be recovered as the supernatant.
【００５６】上記後処理では、処理水量が大幅に低減さ
れていることが特徴であるが、上記以外のいかなる処理
方法も効果的に適用可能である。The above-mentioned post-treatment is characterized in that the amount of treated water is greatly reduced, but any treatment method other than the above is effectively applicable.
【００５７】本実施例では、蒸発濃縮装置として多重効
用式のものを使用したが、蒸気圧縮式や多段フラッシュ
式の装置ももちろん適用可能である。In the present embodiment, a multi-effect type was used as the evaporative concentration device, but a vapor compression type or multi-stage flash type device can of course be applied.
【００５８】実施例２ この実施例を示す図５において、フッ素含有排水の中和
剤として苛性カリ水溶液を使用した。この場合、濃縮に
よって析出する可能性がある塩ＫＦの溶解度は大きく、
上記文献（財団法人日本化学会編、「化学便覧基礎編改
訂３版」、丸善株式会社より昭和５９年６月２５日発
行、Ｐ．II−１６６〜II-173ページ）によれば、２５℃
での溶解度は５０．４重量％である。原理的には、この
実施例では最終濃縮度を実施例１より大幅に上げること
が可能であるが、実際的には、塩濃度が上昇するに連れ
て濃縮水の沸点上昇が大きくなり、蒸発濃縮装置の効率
が低下する。実用的には沸点上昇が３℃を越えない範囲
に濃度を維持する必要がある。このような観点から、こ
の実施例では、最終濃縮水濃度を１０重量％（全フッ素
成分のモル分率としては、０．０３３３）に設定した。Example 2 In FIG. 5 showing this example, an aqueous caustic potash solution was used as a neutralizing agent for fluorine-containing wastewater. In this case, the solubility of the salt KF which may precipitate due to concentration is high,
According to the above-mentioned document (edited by The Chemical Society of Japan, "Chemical Handbook Basic Revised 3rd Edition", published by Maruzen Co., Ltd. on June 25, 1984, pp. II-166 to II-173), 25 ° C.
The solubility in is 0.4% by weight. In principle, in this example, the final degree of enrichment can be increased significantly compared to Example 1, but in practice, as the salt concentration increases, the boiling point of the concentrated water increases and the evaporation The efficiency of the concentrator is reduced. Practically, it is necessary to maintain the concentration within the range where the boiling point rise does not exceed 3 ° C. From this point of view, in this example, the final concentrated water concentration was set to 10% by weight (the molar fraction of the total fluorine component was 0.0333).
【００５９】この実施例における操作条件を決定するた
めの考え方は、実施例１の場合と全く同じであり、最終
濃縮水の全フッ素濃度が大きくなった点が異なるのみで
ある。The concept for determining the operating conditions in this example is exactly the same as in Example 1 except that the total fluorine concentration in the final concentrated water is increased.
【００６０】この実施例では、Ｆとして１００ｐｐｍの
フッ素成分を含む排水１０ｔｏｎ／ｈ（Ｆとして１００
ｐｐｍ）を、濃縮水のｐＨが６．２〜７．３になるよう
にフッ素含有排水に苛性カリ水溶液を添加して蒸発濃縮
装置に供給し、最終濃縮水中のＮａＦ塩濃度を１０重量
％（Ｆとして３２７００ｐｐｍ）に保って処理したとこ
ろ、蒸留水として９．９６ｔｏｎ／ｈの純水が回収され
（回収率９９．６％）、回収水中のフッ素濃度は、６．
５〜０．６５ｐｐｍであった。In this embodiment, 10 ton / h of waste water containing 100 ppm of fluorine component as F (100 as F)
(ppm) to the evaporative concentrator by adding an aqueous caustic potash solution to the fluorine-containing wastewater so that the pH of the concentrated water becomes 6.2 to 7.3, and supply the NaF salt concentration in the final concentrated water to 10 wt% (F). As a result, pure water of 9.96 ton / h was recovered as distilled water (recovery rate 99.6%), and the fluorine concentration in the recovered water was 6.
It was 5 to 0.65 ppm.
【００６１】回収水中の、ＫＦ以外の不純物（有機物、
無機物共に）は極めて少なかったが、実施例１の場合よ
りはやや不純物濃度が高くなった。Impurities other than KF (organic substances,
However, the impurity concentration was slightly higher than that in the case of Example 1.
【００６２】他方、濃縮水量は３０．６ｋｇ／ｈであっ
て、フッ素含有排水量の１／３２７となり、後処理が非
常に経済的になった。On the other hand, the amount of concentrated water was 30.6 kg / h, which was 1/327 of the amount of fluorine-containing wastewater, and the post-treatment became very economical.
【００６３】[0063]
【発明の効果】本発明によれば、下記の効果が発揮され
る。According to the present invention, the following effects are exhibited.
【００６４】スラッジの発生なしに、フッ素含有排水
を大幅に減量できる。Fluorine-containing wastewater can be significantly reduced without the generation of sludge.
【００６５】フッ素含有量が極めて小さく、他の非揮
発性の有機物および無機物を全く含まない高純度の蒸留
水を回収できる。High-purity distilled water having a very small fluorine content and containing no other non-volatile organic and inorganic substances can be recovered.
【００６６】装置の信頼性が高く、安定な操業が可能
である。The device is highly reliable and stable operation is possible.
【００６７】装置の設置面積が小さくてすむ。The installation area of the device can be small.
【図１】ＨＦ水溶液の気液平衡データを示すグラフであ
る。FIG. 1 is a graph showing vapor-liquid equilibrium data of an HF aqueous solution.
【図２】純水に溶解した全ＨＦ量と未解離のＨＦ量の関
係およびその際のｐＨ値を示すグラフである。FIG. 2 is a graph showing the relationship between the total amount of HF dissolved in pure water and the amount of undissociated HF, and the pH value at that time.
【図３】ｐＨを制御することによる未解離のＨＦ濃度の
変化（計算値）と気化するＨＦ量を抑制するために必要
なｐＨの値を決める操作線を示すグラフである。FIG. 3 is a graph showing a change (calculated value) in the undissociated HF concentration by controlling the pH and an operation line for determining the pH value required to suppress the vaporized HF amount.
【図４】本発明の実施例１を示すフローシートである。FIG. 4 is a flow sheet showing Example 1 of the present invention.
【図５】本発明の実施例２を示すフローシートである。FIG. 5 is a flow sheet showing Example 2 of the present invention.
【図６】フッ素含有排水の従来の処理方法を示すフロー
シートである。FIG. 6 is a flow sheet showing a conventional method for treating fluorine-containing wastewater.
Claims (3)
量を減少させると同時に大部分の水を蒸留水として回収
する方法であって、蒸発濃縮の前に上記排水にアルカリ
性水溶液を添加することによって水の蒸発に伴うフッ化
水素酸の気化を最小限に抑えることを特徴とするフッ素
含有排水の処理方法。1. A method of evaporatively concentrating fluorine-containing wastewater to reduce the amount of concentrated water and at the same time to recover most of the water as distilled water, wherein an alkaline aqueous solution is added to the wastewater before evaporative concentration. A method for treating fluorine-containing wastewater, wherein vaporization of hydrofluoric acid accompanying evaporation of water is minimized.
液を使用し、蒸発濃縮装置出口における最終濃縮水のｐ
Ｈを６から８．５の範囲となるよう苛性ソーダの添加量
を調整し、蒸発濃縮装置出口の最終濃縮水中のＮａＦ濃
度を３．６重量％以下に制御して、フッ素濃度３．３ｐ
ｐｍ以下の蒸留水を回収することを特徴とする請求項１
記載の方法。2. A caustic soda aqueous solution is used as the alkaline aqueous solution, and p of the final concentrated water at the outlet of the evaporative concentrator is used.
The amount of caustic soda added was adjusted so that H was in the range of 6 to 8.5, the NaF concentration in the final concentrated water at the outlet of the evaporative concentration device was controlled to be 3.6% by weight or less, and the fluorine concentration was 3.3 p.
2. Distilled water of pm or less is recovered.
The described method.
を使用し、蒸発濃縮装置出口の最終濃縮水のｐＨを６か
ら８．５の範囲となるよう添加する苛性カリ量を調整
し、蒸発濃縮装置出口の最終濃縮水中のＫＦ濃度を１０
重量％以下に制御して、フッ素濃度６．５ｐｐｍ以下の
蒸留水を回収することを特徴とする請求項１記載の方
法。3. An aqueous caustic potash solution is used as the alkaline aqueous solution, and the amount of caustic potash added is adjusted so that the pH of the final concentrated water at the outlet of the evaporative concentrator is in the range of 6 to 8.5. KF concentration in water is 10
The method according to claim 1, wherein the distilled water having a fluorine concentration of 6.5 ppm or less is recovered by controlling the content to be not more than wt%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08514996A JP3284260B2 (en) | 1996-04-08 | 1996-04-08 | Treatment method for fluorine-containing wastewater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08514996A JP3284260B2 (en) | 1996-04-08 | 1996-04-08 | Treatment method for fluorine-containing wastewater |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09271785A true JPH09271785A (en) | 1997-10-21 |
| JP3284260B2 JP3284260B2 (en) | 2002-05-20 |
Family
ID=13850619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP08514996A Expired - Fee Related JP3284260B2 (en) | 1996-04-08 | 1996-04-08 | Treatment method for fluorine-containing wastewater |
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| JP (1) | JP3284260B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007160172A (en) * | 2005-12-12 | 2007-06-28 | Sasakura Engineering Co Ltd | Method and apparatus for treating hydrofluoric acid-containing waste water |
| US7311799B2 (en) | 2002-11-28 | 2007-12-25 | Sasakura Engineering Co., Ltd. | Hydrofluoric acid wastewater treatment method and device |
| KR20160122031A (en) * | 2015-04-13 | 2016-10-21 | 최윤진 | Method for preparing sodium fluoride from fluorine-containing waste slurry |
| CN106178555A (en) * | 2016-09-04 | 2016-12-07 | 谢永宁 | A kind of strong brine vaporising device |
| CN114314991A (en) * | 2022-01-21 | 2022-04-12 | 浙江天地环保科技股份有限公司 | pH adjusting device of MVR evaporative crystallization system and working method thereof |
-
1996
- 1996-04-08 JP JP08514996A patent/JP3284260B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7311799B2 (en) | 2002-11-28 | 2007-12-25 | Sasakura Engineering Co., Ltd. | Hydrofluoric acid wastewater treatment method and device |
| JP2007160172A (en) * | 2005-12-12 | 2007-06-28 | Sasakura Engineering Co Ltd | Method and apparatus for treating hydrofluoric acid-containing waste water |
| JP4549289B2 (en) * | 2005-12-12 | 2010-09-22 | 株式会社ササクラ | Hydrofluoric acid wastewater treatment method and hydrofluoric acid wastewater treatment equipment |
| KR20160122031A (en) * | 2015-04-13 | 2016-10-21 | 최윤진 | Method for preparing sodium fluoride from fluorine-containing waste slurry |
| CN106178555A (en) * | 2016-09-04 | 2016-12-07 | 谢永宁 | A kind of strong brine vaporising device |
| CN114314991A (en) * | 2022-01-21 | 2022-04-12 | 浙江天地环保科技股份有限公司 | pH adjusting device of MVR evaporative crystallization system and working method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3284260B2 (en) | 2002-05-20 |
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