JP3666612B2 - Treatment method of phosphite-containing waste liquid - Google Patents
Treatment method of phosphite-containing waste liquid Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、亜リン酸塩含有廃液中に残留溶存する亜リン酸塩成分を効率良く分離除去して廃棄可能な状態に無害化させる亜リン酸塩含有廃液の処理方法に関する。
【０００２】
【従来の技術】
従来、次亜リン酸塩を製造する際に副生する亜リン酸塩、無電解ニッケルめっきの使用済み老化液から回収される亜リン酸塩等は、有効な用途が無く、その殆どが海洋投棄や管理型の最終処分場で埋め立て処分されている。しかし、海洋投棄は地球環境保全の点から好ましくないとされ、ロンドンダンピング条約により１９９６年から禁止されることになっており、また陸上での埋め立て処分にしても予め環境破壊を伴うことのない安全な形態に加工しなければならず、年々産業廃棄物の処分場の確保が困難になっているのが現状である。
【０００３】
そこで、それら亜リン酸塩含有廃液中に含まれる亜リン酸塩を効率良く、工業的に有利に処理する方法が望まれ、従来より様々提案されている。
例えば、▲１▼過酸化水素や次亜塩素酸ナトリウム等の酸化剤を加えて亜リン酸をオルトリン酸に酸化し、これにカルシウム塩を添加して酸化により生成したオルトリン酸をリン酸カルシウムとして沈澱除去する方法がある。
【０００４】
また、▲２▼次亜リン酸及び亜リン酸を含む化学めっき廃液を電極として二酸化鉛電極を使用して亜リン酸をオルト燐酸に電解酸化して沈澱除去する方法がある（特開平６−９９１７８号公報）。
他に、▲３▼化学めっき廃液中の亜リン酸を拡散透析で分離除去し、次いでその透析液中の亜リン酸を電解透析により分離除去する方法がある（特開平６−１４５９９５号公報）。
【０００５】
また、本発明者らは、▲４▼無電解めっき老化液中に溶存するめっき金属イオンを粉体面にめっき被覆し分離除去した後、母液残存する亜リン塩等を亜鉛化合物で亜リン酸亜鉛として回収する方法を提案している。（特開平６−７３５５０号公報）
【０００６】
【発明が解決しようとする課題】
しかしながら、上記▲１▼の酸化剤を使用する方法は、過酸化水素等の酸化剤の酸化率が低く過剰量の酸化剤を加えたり、酸化率の高い領域にｐＨを調整したりする必要がある等の問題点がある。
【０００７】
また、▲２▼の電解酸化する方法は、電解槽の設備投資を必要とするために安価に処理できない。のみならず生成するリン酸アルカリは有機酸が多く含まれているため、有効利用が困難で、さらに処理するための工程が必要である。
▲３▼の電解透析法は、亜リン酸分の濃度が低い場合は、比較的亜リン酸の分離除去は容易であるが、濃度が高い場合は除去率が極端に低くなる欠点を有している。
【０００８】
また、▲４▼の方法は、亜リン酸塩と亜鉛化合物との反応率はｐＨ依存性が大きいため、酸性側での反応では分離後の残液に未反応の亜鉛イオンや亜リン酸イオンが残ってしまい、廃水基準を越えたり、亜リン酸亜鉛の用途がないと極端に適用が制限されるといった欠点を有する。
【０００９】
本発明は、上記問題点に鋭意に鑑みた結果、亜リン酸塩含有廃液に石膏を添加して複分解反応させることにより、亜リン酸成分を亜リン酸カルシウムとして高収率で、しかも効率良く工業的に有利に回収できることを知見し本発明を完成させた。
【００１０】
【課題を解決するための手段】
すなわち、本発明は、亜リン酸塩の濃度が１５．１〜３０重量％の亜リン酸塩含有廃液より亜リン酸成分を亜リン酸カルシウムとして沈澱生成させて分離回収する亜リン酸塩含有廃液の処理方法において、該廃液に平均粒子径が１〜５０μｍの石膏を添加して複分解反応により亜リン酸カルシウムを生成させることを特徴とする亜リン酸塩含有廃液の処理方法を提供することにある。
【００１１】
上記の亜リン酸塩含有廃液の処理方法において、複分解反応は、ｐＨ７〜９、温度４０〜６０℃において、亜リン酸量に対し１．２〜１．６倍モルの石膏を作用させるのが好ましい。
また、本発明に用いられる亜リン酸塩含有廃液は、亜リン酸ナトリウム含有廃液で、該亜リン酸ナトリウム含有廃液は無電解ニッケルめっき廃液が好適である。
【００１２】
【発明の実施の形態】
本発明の亜リン酸塩含有廃液の処理方法は、亜リン酸塩含有廃液より亜リン酸成分を亜リン酸カルシウムとして沈澱生成させて、これを分離回収する亜リン酸塩含有廃液の処理方法において、該廃液に石膏を添加して複分解反応により亜リン酸カルシウムを生成させることを特徴とする。
【００１３】
本発明が処理対象とする亜リン酸塩含有廃液は、石膏と複分解反応を行うことができる亜リン酸塩を含有する廃液であればよく、それらの中で特に亜リン酸ナトリウム含有廃液が好ましい。亜リン酸ナトリウム含有廃液の種類は、特に制限されないが、代表的には次亜リン酸ナトリウムを製造する際に副生する廃液、無電解ニッケルめっき工程で還元剤として用いられ、使用済みとなった老化液、あるいは三塩化燐を塩素剤又は反応剤として使用した際に副生する廃液を挙げることができる。
【００１４】
また、本発明の方法は、高濃度の亜リン酸塩の他に次亜リン酸塩、有機酸塩及び重金属を含む無電解ニッケルめっき廃液にも適用できる。
なお、無電解ニッケルめっき廃液などの如く、廃液中にＮｉ2+、Ｃｏ2+のような金属イオンを含有しているものにあっては、廃液に石膏を添加して複分解反応を行なう処理に当たり、予め、これらの金属イオンを分離除去しておくことが望ましい。
【００１５】
本発明の特徴は、上記複分解処理方法において、安価な石膏を使用することである。石膏を使用した場合、石膏の溶解が反応律速となって亜リン酸イオンと反応して、亜リン酸カルシウムが沈澱する。この時、石膏は反応性の関係から微細な粒子ほど好ましく、その平均粒子径は１〜５０μｍ、好ましくは１０〜５０μｍ、さらに好ましくは約２０μｍ程度である。粒子径が５０μｍを越えると石膏の溶解速度の減少から複分解が遅くなり、処理能力が極端に落ち、また１μｍ未満のものは工業的に入手することが困難な理由による。
【００１６】
かかる処理で使用する石膏の量は含有する亜リン酸量に対して１．１〜１．８倍モル、好ましくは１．２〜１．６倍モルである。反応時におけるｐＨは７〜９、好ましくは８付近である。
【００１７】
反応温度は、４０〜６０℃、好ましくは４５〜５５℃である。反応時間は、０．５時間以上であればよいが、通常０．５〜１０時間、好ましくは１〜３時間で有る。
【００１８】
本発明においては、亜リン酸塩の濃度は特に制限することはないが、通常３０重量％以下、好ましくは２０重量％以下が望ましい。本発明によれば、このように３０重量％程度の高濃度であっても高い回収率で亜リン酸塩を亜リン酸カルシウムとして回収することができる。
【００１９】
本発明に係る亜リン酸塩含有廃液の処理方法は、廃液中に含有する亜リン酸塩と石膏との複分解反応により亜リン酸カルシウムを生成させることを特徴とする。
石膏は難溶性塩であるから、反応系はこのために終始固液両相ではあるが、予想外に次の反応式（Ｉ）に示す複分解反応が進行し、亜リン酸イオンは固定化される。
しかも、脱硫石膏を用いれば従来使用されている塩化カルシウム等のカルシウム源と比べると安価であり、合目的的に処理することができる。
【００２０】
その亜リン酸ナトリウム含有廃液の処理における反応式は以下の通りと考えられる。
【００２１】
【化１】
Ｎａ2 ＨＰＯ3 ＋ＣａＳＯ4 →ＣａＨＰＯ3 ＋Ｎａ2 ＳＯ4 （Ｉ）
上記反応において、石膏の溶解が反応律速となって亜リン酸イオンと反応し、亜リン酸カルシウムとして沈澱し、液相には硫酸ナトリウムを生成する。したがって、石膏は微粒子の方が亜リン酸の固定率の向上と処理時間との関係から特に好ましい。
【００２２】
【実施例】
以下、本発明を実施例に基づいて具体的に説明する。
【００２３】
実施例１
亜リン酸イオン（１６７ｇ／ｌ）を含有する亜リン酸塩含有廃液２５０ｍｌにアルカリ剤（苛性ソーダ水溶液）を添加してｐＨ８とし、該廃液を５０℃に昇温させた。該廃液に平均粒子径２０μｍの石膏（２水塩）１０９ｇ（亜リン酸イオンに対し１．２倍モル）を添加し、２時間反応をおこなった。反応終了後、遠心分離機を用いて濾過をおこない、遠心分離機内の濾過ケーキを５００ｍｌの水で２回洗浄した。濾過ケーキは、白色で濾過性の良いものであった。回収された濾過液の量は１００ｍｌであり、該液中に残る未反応亜リン酸イオンは４．０ｇ／ｌであった。これより、亜リン酸イオンの除去率は９９％であった。
【００２４】
実施例２
実施例１と同様の廃液２５０ｍｌにアルカリ剤（苛性ソーダ水溶液）を添加してｐＨ９とし、４０℃に昇温させた。該廃液に平均粒子径５０μｍの石膏（２水塩）１２７ｇ（亜リン酸イオンに対し１．４倍モル）を添加し、３時間攪拌し反応をおこなった。反応液の処理液は遠心分離機を用いて濾過を行い、遠心分離機内の濾過ケーキを５００ｍｌの水で２回洗浄した。濾過ケーキは、白色で濾過性の良いものであった。回収された濾過液の量は１６０ｍｌであり、該液中に残る未反応亜リン酸イオンは１３ｇ／ｌであった。これより、亜リン酸イオンの除去率は９５％であった。
【００２５】
実施例３
実施例１と同様の廃液２５０ｍｌにアルカリ剤（苛性ソーダ水溶液）を添加してｐＨ９とし、４０℃に昇温させた。該廃液に平均粒子径２０μｍの石膏（２水塩）１４６ｇ（亜リン酸イオンに対し１．６倍モル）を４０％スラリー溶液として添加し、１時間攪拌し反応をおこなった。反応液の処理液は遠心分離機を用いて濾過を行い、遠心分離機内の濾過ケーキを５００ｍｌの水で２回洗浄した。濾過ケーキは、白色で濾過性の良いものであった。回収された濾過液の量は、３２０ｍｌであり、該液中に残る未反応亜リン酸イオンは５．２ｇ／ｌであった。これより、亜リン酸イオンの除去率は９６％であった。
【００２６】
実施例４
脱ニッケル除去処理後の無電解ニッケルめっき廃液（ニッケルイオン：０．０３ｇ／ｌ、リンゴ酸イオン：１６ｇ／ｌ、コハク酸イオン：１２ｇ／ｌ、亜リン酸イオン：１６７ｇ／ｌ）２５０ｍｌにアルカリ剤を添加してｐＨ８とし、該液を５０℃に昇温させた。上記該廃液に平均粒子径２０μｍの石膏（２水塩）１０９ｇ（亜リン酸イオンに対し１．２倍モル）を添加し、２時間反応を行った。反応終了後、遠心分離機を用いて濾過をおこない、遠心分離機内の濾過ケーキを５００ｍｌの水で２回洗浄した。濾過ケーキは、白色で濾過性の良いものであった。回収された濾過液は、１００ｍｌであり、該液中に残る未反応亜リン酸イオンは４．０ｇ／ｌであった。これより、亜リン酸イオンの除去率は９９％であった。
【００２７】
実施例５
亜リン酸イオン１５１ｇ／ｌを含有する廃液２５０ｍｌに酸性溶液を添加してｐＨ６とし、５０℃に昇温させた。該廃液に平均粒子径２０μｍの石膏（２水塩）９９ｇ（亜リン酸イオンに対し１．２倍モル）を添加して、２時間反応を行った。反応終了後、遠心分離機を用いて濾過をおこない、遠心分離機内の濾過ケーキを５００ｍｌの水で２回洗浄した。濾過ケーキは、多量の水分を含んでいた。回収された濾過液は、１１０ｍｌであり、該液中に残る未反応亜リン酸イオンは１０２ｇ／ｌであった。これより、亜リン酸イオンの除去率は７０％であった。
【００２８】
実施例６
実施例５と同様の廃液２５０ｍｌにアルカリ剤を添加してｐＨ１０とし、６０℃に昇温させた。該廃液に平均粒子を径２０μｍの石膏（２水塩）９９ｇ（亜リン酸イオンに対し１．２倍モル）を添加して、２時間反応を行った。反応終了後、遠心分離機を用いて濾過をおこない、遠心分離機内の濾過ケーキを５００ｍｌの水で２回洗浄した。濾過ケーキは、多量の水分を含んでいた。回収された濾過液は１２０ｍｌであり、該液中に残る未反応亜リン酸イオンは８５ｇ／ｌであった。これより、亜リン酸イオンの除去率は７３％であった。
【００３０】
【発明の効果】
以上のとおり、本発明の処理方法に従えば亜リン酸塩含有廃液に残留溶存する亜リン酸イオンを高濃度であっても効率良く分離除去し、亜リン酸カルシウムとして回収することができる。そのうえ、分離回収された亜リン酸カルシウムは、新たな防錆顔料等の用途として再利用することができることから、今後増大する亜リン酸ナトリウム含有廃液の集中的な処理技術として大きな有用性が期待できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating a phosphite-containing waste liquid that efficiently separates and removes the phosphite component remaining in the phosphite-containing waste liquid and renders it harmless to a disposable state.
[0002]
[Prior art]
Conventionally , phosphites by-produced when producing hypophosphites, phosphites recovered from used aging solutions of electroless nickel plating have no effective use, and most of them are marine It is disposed of in landfills at dumped or managed final disposal sites. However, ocean dumping is considered undesirable from the viewpoint of global environmental protection, and it has been banned since 1996 by the London Dumping Convention, and it is safe without causing environmental destruction in advance even when landfilled on land. It is difficult to secure a disposal site for industrial waste year by year.
[0003]
Therefore, a method for efficiently and industrially treating the phosphite contained in the phosphite-containing waste liquid is desired, and various proposals have been conventionally made.
For example, (1) oxidizing agents such as hydrogen peroxide and sodium hypochlorite are added to oxidize phosphorous acid to orthophosphoric acid, and calcium salts are added to this to remove the orthophosphoric acid produced by oxidation as calcium phosphate and remove it. There is a way to do it.
[0004]
Also, (2) there is a method of removing precipitates by electrolytic oxidation of phosphorous acid to orthophosphoric acid using a lead dioxide electrode with chemical plating waste solution containing hypophosphorous acid and phosphorous acid as an electrode (Japanese Patent Laid-Open No. 6-2006). No. 99178).
In addition, (3) there is a method in which phosphorous acid in the chemical plating waste solution is separated and removed by diffusion dialysis, and then phosphorous acid in the dialysate is separated and removed by electrodialysis (Japanese Patent Laid-Open No. 6-145959). .
[0005]
In addition, the present inventors (4) after plating metal ions dissolved in the electroless plating aging solution are coated on the powder surface and separated and removed, and then the phosphorous salts remaining in the mother liquor are phosphorous acid with zinc compounds. A method of recovering as zinc is proposed. (JP-A-6-73550)
[0006]
[Problems to be solved by the invention]
However, in the method using the oxidizing agent of the above (1), it is necessary to add an excessive amount of oxidizing agent with a low oxidation rate of an oxidizing agent such as hydrogen peroxide or to adjust the pH in a region where the oxidation rate is high. There are some problems.
[0007]
In addition, the method (2) of electrolytic oxidation requires an equipment investment for an electrolytic cell and cannot be treated at low cost. In addition, since the produced alkali phosphate contains a large amount of organic acid, it is difficult to effectively use it, and a process for further processing is necessary.
The electrodialysis method (3) is relatively easy to separate and remove phosphorous acid when the concentration of phosphorous acid is low, but has a disadvantage that the removal rate becomes extremely low when the concentration is high. ing.
[0008]
In the method (4), since the reaction rate between the phosphite and the zinc compound is highly pH dependent, unreacted zinc ions and phosphite ions are present in the remaining liquid after separation in the reaction on the acidic side. However, if the wastewater standard is exceeded or there is no use of zinc phosphite, the application is extremely limited.
[0009]
As a result of diligently considering the above-mentioned problems, the present invention adds a gypsum to a phosphite-containing waste liquor to cause a metathesis reaction, thereby making the phosphite component calcium phosphite in a high yield and efficiently industrial. Thus, the present invention has been completed.
[0010]
[Means for Solving the Problems]
That is, the present invention relates to a phosphite- containing waste liquid in which a phosphite component is precipitated as calcium phosphite and separated and recovered from a phosphite-containing waste liquid having a phosphite concentration of 15.1 to 30% by weight . An object of the present invention is to provide a method for treating a phosphite-containing waste liquid, characterized in that gypsum having an average particle size of 1 to 50 μm is added to the waste liquid to produce calcium phosphite by metathesis reaction.
[0011]
In the above-described method for treating a phosphite-containing waste liquid, the metathesis reaction is performed at a pH of 7 to 9 and a temperature of 40 to 60 ° C. by applying 1.2 to 1.6 times moles of gypsum to the amount of phosphorous acid. preferable.
The phosphite-containing waste liquid used in the present invention is a sodium phosphite-containing waste liquid, and the sodium phosphite-containing waste liquid is preferably an electroless nickel plating waste liquid.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The method for treating a phosphite-containing waste liquid according to the present invention is a method for treating a phosphite-containing waste liquid in which a phosphite component is precipitated as calcium phosphite from a phosphite-containing waste liquid and separated and recovered. Gypsum is added to the waste liquid to produce calcium phosphite by metathesis reaction.
[0013]
The phosphite-containing waste liquid to be treated by the present invention may be a waste liquid containing phosphite capable of performing a metathesis reaction with gypsum, and among them, a sodium phosphite-containing waste liquid is particularly preferable. . The type of sodium phosphite-containing waste liquid is not particularly limited, but typically, it is used as a reducing agent in the waste liquid produced as a by-product in the production of sodium hypophosphite, and in the electroless nickel plating process, and is used. An aging solution or a waste solution by-produced when phosphorus trichloride is used as a chlorinating agent or a reaction agent can be used.
[0014]
Further, the method of the present invention can be applied to electroless nickel plating waste liquid containing hypophosphite, organic acid salt and heavy metal in addition to high concentration phosphite.
If the waste liquid contains metal ions such as Ni 2+ and Co 2+ , such as electroless nickel plating waste liquid, it will be treated in a metathesis reaction by adding gypsum to the waste liquid. It is desirable to separate and remove these metal ions in advance.
[0015]
A feature of the present invention is that inexpensive gypsum is used in the metathesis processing method. When gypsum is used, dissolution of gypsum becomes reaction rate-determining and reacts with phosphite ions to precipitate calcium phosphite. At this time, gypsum is preferably finer particles in view of reactivity, and the average particle diameter is 1 to 50 μm, preferably 10 to 50 μm, and more preferably about 20 μm. When the particle diameter exceeds 50 μm, metathesis is delayed due to the decrease in the dissolution rate of gypsum, the processing ability is extremely lowered, and those having a particle diameter of less than 1 μm are difficult to obtain industrially.
[0016]
The amount of gypsum used in such treatment is 1.1 to 1.8 times mol, preferably 1.2 to 1.6 times mol, based on the amount of phosphorous acid contained. The pH during the reaction is 7-9, preferably around 8.
[0017]
The reaction temperature is 40-60 ° C, preferably 45-55 ° C. Although reaction time should just be 0.5 hours or more, it is 0.5 to 10 hours normally, Preferably it is 1-3 hours.
[0018]
In the present invention, the concentration of phosphite is not particularly limited, but it is usually 30% by weight or less, preferably 20% by weight or less. According to the present invention, phosphite can be recovered as calcium phosphite at a high recovery rate even at a high concentration of about 30% by weight.
[0019]
The method for treating a phosphite-containing waste liquid according to the present invention is characterized in that calcium phosphite is produced by a metathesis reaction between phosphite and gypsum contained in the waste liquid.
Because gypsum is a sparingly soluble salt, the reaction system is always in a solid-liquid phase for this purpose, but unexpectedly, the metathesis reaction shown in the following reaction formula (I) proceeds and the phosphite ions are immobilized. The
In addition, if desulfurized gypsum is used, it is less expensive than calcium sources such as calcium chloride that are conventionally used, and can be treated appropriately.
[0020]
The reaction formula in the treatment of the sodium phosphite-containing waste liquid is considered as follows.
[0021]
[Chemical 1]
Na 2 HPO 3 + CaSO 4 → CaHPO 3 + Na 2 SO 4 (I)
In the above reaction, the dissolution of gypsum becomes the rate-limiting reaction, reacts with phosphite ions, precipitates as calcium phosphite, and produces sodium sulfate in the liquid phase. Therefore, fine particles of gypsum are particularly preferable from the relationship between the improvement of phosphorous acid fixation and the treatment time.
[0022]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
[0023]
Example 1
An alkaline agent (caustic soda aqueous solution) was added to 250 ml of a phosphite-containing waste liquid containing phosphite ions (167 g / l) to adjust to pH 8, and the waste liquid was heated to 50 ° C. 109 g of gypsum (dihydrate) with an average particle size of 20 μm (1.2 times mol with respect to phosphite ion) was added to the waste liquid and reacted for 2 hours. After completion of the reaction, filtration was performed using a centrifuge, and the filter cake in the centrifuge was washed twice with 500 ml of water. The filter cake was white and had good filterability. The amount of the collected filtrate was 100 ml, and the unreacted phosphite ion remaining in the liquid was 4.0 g / l. From this, the removal rate of the phosphite ion was 99%.
[0024]
Example 2
Alkaline agent (caustic soda aqueous solution) was added to 250 ml of the same waste liquid as in Example 1 to adjust the pH to 9, and the temperature was raised to 40 ° C. To the waste liquid, 127 g of gypsum (dihydrate) having an average particle size of 50 μm (1.4 mol per mol of phosphite ion) was added, and the reaction was carried out by stirring for 3 hours. The reaction solution was filtered using a centrifuge, and the filter cake in the centrifuge was washed twice with 500 ml of water. The filter cake was white and had good filterability. The amount of the filtrate collected was 160 ml, and the unreacted phosphite ion remaining in the liquid was 13 g / l. From this, the removal rate of the phosphite ion was 95%.
[0025]
Example 3
Alkaline agent (caustic soda aqueous solution) was added to 250 ml of the same waste liquid as in Example 1 to adjust the pH to 9, and the temperature was raised to 40 ° C. To the waste liquid, 146 g of gypsum (dihydrate) having an average particle diameter of 20 μm (1.6 times moles relative to phosphite ions) was added as a 40% slurry solution, and the reaction was carried out by stirring for 1 hour. The reaction solution was filtered using a centrifuge, and the filter cake in the centrifuge was washed twice with 500 ml of water. The filter cake was white and had good filterability. The amount of the filtrate collected was 320 ml, and the amount of unreacted phosphite ions remaining in the liquid was 5.2 g / l. As a result, the removal rate of phosphite ions was 96%.
[0026]
Example 4
Electroless nickel plating waste liquid after nickel removal treatment (nickel ion: 0.03 g / l, malate ion: 16 g / l, succinate ion: 12 g / l, phosphite ion: 167 g / l) in 250 ml alkaline agent Was added to pH 8, and the liquid was heated to 50 ° C. 109 g of gypsum (dihydrate) having an average particle size of 20 μm (1.2 times mol with respect to phosphite ion) was added to the waste liquid, followed by reaction for 2 hours. After completion of the reaction, filtration was performed using a centrifuge, and the filter cake in the centrifuge was washed twice with 500 ml of water. The filter cake was white and had good filterability. The collected filtrate was 100 ml, and the amount of unreacted phosphite ions remaining in the liquid was 4.0 g / l. From this, the removal rate of the phosphite ion was 99%.
[0027]
Example 5
An acidic solution was added to 250 ml of waste liquid containing 151 g / l of phosphite ion to adjust the pH to 6 and the temperature was raised to 50 ° C. 99 g of gypsum (dihydrate) having an average particle size of 20 μm (1.2 times mol with respect to phosphite ion) was added to the waste liquid and reacted for 2 hours. After completion of the reaction, filtration was performed using a centrifuge, and the filter cake in the centrifuge was washed twice with 500 ml of water. The filter cake contained a large amount of moisture. The collected filtrate was 110 ml, and the unreacted phosphite ion remaining in the liquid was 102 g / l. Thus, the removal rate of phosphite ions was 70%.
[0028]
Example 6
An alkaline agent was added to 250 ml of the same waste liquid as in Example 5 to adjust the pH to 10, and the temperature was raised to 60 ° C. To the waste liquid, 99 g of gypsum (dihydrate) having an average particle diameter of 20 μm (1.2 times mol with respect to phosphite ion) was added and reacted for 2 hours. After completion of the reaction, filtration was performed using a centrifuge, and the filter cake in the centrifuge was washed twice with 500 ml of water. The filter cake contained a large amount of moisture. The collected filtrate was 120 ml, and the unreacted phosphite ion remaining in the liquid was 85 g / l. Accordingly, the removal rate of phosphite ions was 73%.
[0030]
【The invention's effect】
As described above, according to the treatment method of the present invention, phosphite ions remaining in the phosphite-containing waste liquid can be efficiently separated and removed even at a high concentration and recovered as calcium phosphite. In addition, since the separated and recovered calcium phosphite can be reused as a new rust preventive pigment and the like, it can be expected to have great utility as an intensive treatment technique for waste liquid containing sodium phosphite, which will increase in the future.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27987495A JP3666612B2 (en) | 1995-10-04 | 1995-10-04 | Treatment method of phosphite-containing waste liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27987495A JP3666612B2 (en) | 1995-10-04 | 1995-10-04 | Treatment method of phosphite-containing waste liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09100107A JPH09100107A (en) | 1997-04-15 |
| JP3666612B2 true JP3666612B2 (en) | 2005-06-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP27987495A Expired - Fee Related JP3666612B2 (en) | 1995-10-04 | 1995-10-04 | Treatment method of phosphite-containing waste liquid |
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| Country | Link |
|---|---|
| JP (1) | JP3666612B2 (en) |
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1995
- 1995-10-04 JP JP27987495A patent/JP3666612B2/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| JPH09100107A (en) | 1997-04-15 |
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