JP3466646B2 - Method of treating water containing hydrogen fluoride and ammonium fluoride - Google Patents
Method of treating water containing hydrogen fluoride and ammonium fluorideInfo
- Publication number
- JP3466646B2 JP3466646B2 JP24862592A JP24862592A JP3466646B2 JP 3466646 B2 JP3466646 B2 JP 3466646B2 JP 24862592 A JP24862592 A JP 24862592A JP 24862592 A JP24862592 A JP 24862592A JP 3466646 B2 JP3466646 B2 JP 3466646B2
- Authority
- JP
- Japan
- Prior art keywords
- fluorine
- fluoride
- packed tower
- water
- calcium carbonate
- 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.)
- Expired - Lifetime
Links
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- Removal Of Specific Substances (AREA)
- Water Treatment By Sorption (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明はフッ素含有水の処理方法
の改良に関するものである。さらに詳しくいえば、本発
明は、フッ素含有水を、そのフッ素濃度が変動しても安
定して高度に処理することができ、水質の良好な処理水
が得られるとともに、フッ素を再資源化可能な高純度の
フッ化カルシウムとして効率よく回収するフッ素含有水
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 an improvement in a method for treating fluorine-containing water. More specifically, the present invention is capable of stably and highly treating fluorine-containing water even if the concentration of fluorine changes, so that treated water with good water quality can be obtained and fluorine can be recycled. The present invention relates to a method for treating fluorine-containing water, which efficiently recovers high-purity calcium fluoride.
【０００２】[0002]
【従来の技術】近年、半導体製造分野やその関連分野、
あるいは各種金属材料、単結晶材料、光学系材料などの
表面処理分野などにおいては、多量のエッチング剤が使
用されており、そして、このエッチング剤としては、主
にフッ化水素や、フッ化水素とフッ化アンモニウムを主
成分とするエッチング剤が用いられている。フッ化水素
を主成分とするエッチング剤は、通常フッ素をＨＦとし
て０.９重量％程度を含む薬剤であって大量に用いられ
ており、一方、フッ化水素及びフッ化アンモニウムを主
成分として含むエッチング剤（バッファードフッ酸）
は、その使用量は少ないものの、フッ素をＨＦとして通
常７重量％程度含有していることから、これらのエッチ
ング剤は廃水系統へ移行した際、高濃度フッ素含有廃液
となる。一方、エッチング途中やエッチング終了時に
は、これらのエッチング剤で処理された材料を大量の洗
浄水で洗浄するため、その洗浄工程からは、大量の低濃
度フッ素含有廃液が排出される。このようなフッ素含有
廃液は、一部分別排出されるところもあるが、一般的に
は総合排水中に流入されている。この総合排水のフッ素
の除去は、通常水酸化カルシウムや塩化カルシウムなど
のカルシウム化合物を添加して、フッ化カルシウムとし
て不溶化し、固液分離したのち、再度その処理液にアル
ミニウム塩やマグネシウム塩を添加し、その水酸化物へ
のフッ素吸着一固液分離を行ったり、あるいはフッ素吸
着樹脂でイオン交換分離するなど、高度処理を施して放
流する方法がとられている。しかしながら、このような
従来法においては、総合廃水中のフッ素濃度の変動が大
きいために、フッ素が排水基準値以下になるように処理
するためには、大過剰のカルシウム化合物の添加が必要
であり、フッ素はフッ化カルシウムとして回収される
が、不純物を多く含むので、再資源として利用するには
不適当であった。また、高度処理においては、水酸化ア
ルミニウムや水酸化マグネシウムのフッ素吸着量が少な
いためにフッ素をかなり含む液を生成し、十分に満足し
うる方法とはいえないという問題があった。また、フッ
素含有廃液を濃厚系廃液と希薄系廃液とに分別し、濃厚
系廃液を炭酸カルシウムで処理する方法も提案されてい
るが、既設工場の排出配管ラインを改造するには構造的
制限もあり、極めて困難であるのが実状である。2. Description of the Related Art In recent years, semiconductor manufacturing fields and related fields,
Alternatively, a large amount of etching agents are used in the field of surface treatment of various metal materials, single crystal materials, optical system materials, etc., and as the etching agents, hydrogen fluoride and hydrogen fluoride are mainly used. An etching agent whose main component is ammonium fluoride is used. An etching agent containing hydrogen fluoride as a main component is usually used in a large amount because it contains fluorine as HF in an amount of about 0.9% by weight, while it contains hydrogen fluoride and ammonium fluoride as main components. Etching agent (buffered hydrofluoric acid)
Although it is used in a small amount, since it normally contains about 7% by weight of fluorine as HF, these etching agents become a high-concentration fluorine-containing waste liquid when transferred to the wastewater system. On the other hand, during or after the etching, since the materials treated with these etching agents are washed with a large amount of washing water, a large amount of low concentration fluorine-containing waste liquid is discharged from the washing step. Although such a fluorine-containing waste liquid may be partially discharged, it is generally flowed into the integrated waste water. To remove the fluorine from this integrated wastewater, calcium compounds such as calcium hydroxide and calcium chloride are usually added to make it insoluble as calcium fluoride, and solid-liquid separation is performed, and then aluminum salts and magnesium salts are added to the treatment liquid again. Then, a method of performing advanced treatment such as fluorine-adsorption solid-liquid separation on the hydroxide, or ion exchange separation with a fluorine-adsorption resin, and discharging the solution are used. However, in such a conventional method, since the fluctuation of the fluorine concentration in the integrated wastewater is large, it is necessary to add a large excess of the calcium compound in order to treat the fluorine so as to be equal to or lower than the wastewater standard value. , Fluorine is recovered as calcium fluoride, but it is unsuitable for recycling as it contains many impurities. Further, in the advanced treatment, since the amount of fluorine adsorbed by aluminum hydroxide or magnesium hydroxide is small, a liquid containing a large amount of fluorine is produced, and there is a problem that it cannot be said to be a sufficiently satisfactory method. A method has also been proposed in which fluorine-containing waste liquid is separated into concentrated waste liquid and dilute waste liquid, and the concentrated waste liquid is treated with calcium carbonate, but there are structural restrictions to modify the exhaust piping line of an existing factory. Yes, and the reality is that it is extremely difficult.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、このような
事情のもとで、フッ素含有水をそのフッ素濃度が変動し
ても安定して高度に処理することができ、水質の良好な
処理水が得られるとともに、フッ素を再資源可能な高純
度のフッ化カルシウムとして効率よく回収することを目
的としてなされたものである。。Under the above circumstances, the present invention is capable of stably and highly treating fluorine-containing water even when the concentration of fluorine varies, and is a treatment of good water quality. It was made for the purpose of efficiently collecting fluorine as high-purity calcium fluoride that can be recycled as well as water. .
【０００４】[0004]
【課題を解決するための手段】本発明者らは、前記目的
を達成するために鋭意研究を重ねた結果、フッ素含有水
を粒状炭酸カルシウム充填層に通水し、さらにフッ素吸
着剤充填層に通水してフッ素含有水を処理するに際し、
該フッ素吸着剤充填層の再生廃液を原水に加えて処理す
ることにより、その目的を達成しうることを見い出し、
この知見に基づいて本発明を完成するに至った。すなわ
ち、本発明は、
（１）フッ化水素及びフッ化アンモニウム含有水を平均
粒径０.１〜０.５mmの粒状炭酸カルシウム充填塔に通水
したのち、フッ素イオンと錯化合物を形成しうる金属イ
オンを吸着した樹脂であるフッ素吸着剤充填塔に通水し
てフッ化水素及びフッ化アンモニウム含有水を処理する
工程において、該フッ素吸着剤充填塔に再生液を注入
し、該フッ素吸着剤充填塔から排出される再生廃液を粒
状炭酸カルシウム充填塔の前段のフッ素含有水に加え、
再資源として利用可能な高純度フッ化カルシウムを粒状
炭酸カルシウム充填塔から間欠的又は連続的に回収する
ことを特徴とするフッ化水素及びフッ化アンモニウム含
有水の処理方法、及び
（２）該粒状炭酸カルシウム充填塔に通水したのち、固
液分離して、該フッ素吸着剤充填塔に通水してフッ化水
素及びフッ化アンモニウム含有水を処理することを特徴
とする第１項記載のフッ化水素及びフッ化アンモニウム
含有水の処理方法、を提供するものである。Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention have passed fluorine-containing water through a granular calcium carbonate packed layer and further into a fluorine adsorbent packed layer. When passing water to treat fluorine-containing water,
It was found that the objective can be achieved by adding the treated waste liquid of the fluorine adsorbent-packed layer to raw water and treating it.
The present invention has been completed based on this finding. That is, according to the present invention, (1) hydrogen fluoride and ammonium fluoride-containing water can be passed through a granular calcium carbonate packed column having an average particle size of 0.1 to 0.5 mm and then form a complex compound with a fluorine ion. In the step of treating hydrogen fluoride and ammonium fluoride-containing water by passing it through a fluorine adsorbent packed tower, which is a resin that has adsorbed metal ions, a regeneration liquid is injected into the fluorine adsorbent packed tower, The recycled waste liquid discharged from the packed tower is added to the fluorine-containing water in the preceding stage of the granular calcium carbonate packed tower,
A method for treating water containing hydrogen fluoride and ammonium fluoride, characterized by intermittently or continuously recovering high-purity calcium fluoride that can be used as a recycle from a granular calcium carbonate packed tower, and (2) the granular After passing water through a calcium carbonate packed tower, solid-liquid separation is carried out, and water is passed through the fluorine adsorbent packed tower to treat hydrogen fluoride- and ammonium fluoride-containing water. A method for treating water containing hydrogen fluoride and ammonium fluoride is provided.
【０００５】以下、添付図面に従って本発明を詳細に説
明する。図１は本発明方法を実施するための１例の説明
図であって、まず、フッ素含有廃水１は原水槽２に貯留
され、原水槽２の廃水は原水ポンプ３によって粒状炭酸
カルシウム充填塔４に供給される。該フッ素含有廃水
は、必要に応じて酸、アルカリ剤の添加によるpH調整
や、濁質が多い場合には、沈澱法や膜により固液分離し
てから、粒状炭酸カルシウム充填塔４に供給してもよ
い。この充填塔４は上向流、下向流のいずれでもよい
が、通液工程でガスが発生することがあるので上向流が
望ましい。また、炭酸カルシウム剤はフッ化カルシウム
に変換するとフッ素との反応性が低下し、処理水のフッ
素濃度が高くなるので、それを防ぐために、あるいは炭
酸カルシウム剤を有効に利用するために、固定床の場合
は２塔以上の直列通水処理が望ましい。さらに設置面積
を少なくするために塔高の高い上向流多段流動床型を用
いるのが有利である。この充填塔４に充填される粒状炭
酸カルシウムの粒子径は０.１〜０.５mmの範囲にあるの
が望ましい。The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of an example for carrying out the method of the present invention. First, a fluorine-containing wastewater 1 is stored in a raw water tank 2, and the wastewater in the raw water tank 2 is charged by a raw water pump 3 into a granular calcium carbonate packed tower 4 Is supplied to. The fluorine-containing wastewater is supplied to the granular calcium carbonate packed tower 4 after pH adjustment by addition of an acid and an alkali agent, if necessary, and in the case of a large amount of suspended matter, solid-liquid separation by a precipitation method or a membrane. May be. The packed column 4 may be either an upward flow or a downward flow, but an upward flow is desirable because gas may be generated in the liquid passing step. Also, when a calcium carbonate agent is converted to calcium fluoride, its reactivity with fluorine decreases and the concentration of fluorine in treated water increases, so in order to prevent it or to effectively use the calcium carbonate agent, a fixed bed In the case of, it is desirable to use two or more towers in series. Further, in order to reduce the installation area, it is advantageous to use an upward flow multi-stage fluidized bed type with a high tower height. The particle size of the granular calcium carbonate packed in the packed tower 4 is preferably in the range of 0.1 to 0.5 mm.
【０００６】次に、この粒状炭酸カルシウム充填塔４を
出た処理水はフッ素吸着剤充填塔５へ供給される。該炭
酸カルシウム充填塔処理水は中性ないし弱アルカリ性に
なることが多いので、必要に応じてpH調整を行う。ま
た、該炭酸カルシウム充填塔から濁質が漏れることがあ
るので、固液分離を行ってからフッ素吸着剤充填塔５へ
通液するのが望ましい。フッ素吸着剤としては、例えば
セリウム、ハフニウム、チタン、ジルコニウム、鉄、ア
ルミニウム、ランタッドなどのフッ素イオンと錯化合物
を形成しうる金属イオンを吸着した樹脂、活性炭、活性
アルミナ、含水酸化チタン、ゼオライト、マグネシアな
どが挙げられる。Next, the treated water discharged from the granular calcium carbonate packed tower 4 is supplied to the fluorine adsorbent packed tower 5. Since the treated water in the calcium carbonate packed tower is often neutral or weakly alkaline, the pH is adjusted if necessary. Further, since the suspended matter may leak from the calcium carbonate packed tower, it is desirable to carry out the solid-liquid separation before passing the solution to the fluorine adsorbent packed tower 5. As the fluorine adsorbent, for example, cerium, hafnium, titanium, zirconium, iron, aluminum, resin adsorbing metal ions capable of forming a complex compound with fluorine ions such as lanthanum, activated carbon, activated alumina, hydrous titanium oxide, zeolite, magnesia. And so on.
【０００７】該フッ素吸着剤充填塔５は、適宜吸着処理
を停止して、再生液貯槽６からポンプ７により、再生剤
を通常下向流に通水して再生処理が行われる。再生剤と
しては、例えば水酸化カリウム、水酸化ナトリウム、炭
酸ナトリウム、塩酸、硫酸などの水溶液が用いられる。
フッ素含有再生廃液は再生廃液貯槽８に貯留されたの
ち、ポンプ９により、炭酸カルシウム充填塔４の前段、
例えば原水槽２に送液され、フッ素含有水と共に粒状炭
酸カルシウム充填塔４で処理されて、その中のフッ素の
大部分が除去される。該炭酸カルシウム充填塔４から、
生成したフッ化カルシウムを間欠的又は連続的に抜き出
し、新しい粒状炭酸カルシウムを充填する。抜き出した
フッ化カルシウムは脱水後、再資源として利用すること
ができる。In the fluorine adsorbent packed tower 5, the adsorption process is appropriately stopped, and the regenerant is normally passed in a downward flow from the regenerant liquid storage tank 6 by the pump 7 to perform the regeneration process. As the regenerant, for example, an aqueous solution of potassium hydroxide, sodium hydroxide, sodium carbonate, hydrochloric acid, sulfuric acid or the like is used.
The fluorine-containing regenerated waste liquid is stored in the regenerated waste liquid storage tank 8 and is then pumped by the pump 9 to the front stage of the calcium carbonate packed tower 4.
For example, the solution is sent to the raw water tank 2 and treated with the fluorine-containing water in the granular calcium carbonate packed tower 4 to remove most of the fluorine therein. From the calcium carbonate packed tower 4,
The produced calcium fluoride is intermittently or continuously extracted and filled with new granular calcium carbonate. The extracted calcium fluoride can be reused as a resource after dehydration.
【０００８】[0008]
【実施例】次に実施例により本発明をさらに詳細に説明
するが、本発明はこの例によってなんら限定されるもの
ではない。The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.
【０００９】実施例１
厚木市水に、試薬のフッ化水素及びフッ化アンモニウム
をそれぞれ１００mg・Ｆ／リットル及び５００mg・Ｆ／
リットルになるように溶解した原水を調製した。径０.
３２mmの炭酸カルシウム１００mlを充填したカラムに上
記原水を通水し、その処理液をさらにセリウム系フッ素
吸着剤［旭硝子(株)製、ＲＥＡＤ−Ｆ］１００mlを充填
したカラムに直列に５００ml／hrの流量で通水し、各処
理水のフッ素濃度を分析した。なお、０〜１０時間は原
水のフッ素濃度を２００mg／リットル、１０〜２０時間
は１０００mg／リットルとし、２０〜３０時間以降は元
の２００mg／リットルに戻した。また、７０時間目にフ
ッ素吸着剤を水酸化ナトリウム水溶液で再生し、得られ
た再生廃液（フッ素濃度１５００mg／リットル）５００
mlを５ml／hrずつ原水に戻した。結果を第１表に示す。Example 1 100 mg · F / liter and 500 mg · F / liter of hydrogen fluoride and ammonium fluoride as reagents were added to Atsugi city water, respectively.
Raw water was prepared by dissolving it so that it became liter. Diameter 0.
The raw water was passed through a column filled with 100 ml of 32 mm calcium carbonate, and the treatment liquid was further serially connected to a column filled with 100 ml of a cerium-based fluorine adsorbent [READ-F] manufactured by Asahi Glass Co., Ltd. at a rate of 500 ml / hr. Water was passed at a flow rate, and the fluorine concentration of each treated water was analyzed. The fluorine concentration in the raw water was set to 200 mg / liter for 0 to 10 hours, 1000 mg / liter for 10 to 20 hours, and the original 200 mg / liter was reset for 20 to 30 hours. Also, at the 70th hour, the fluorine adsorbent was regenerated with an aqueous sodium hydroxide solution to obtain a regenerated waste liquid (fluorine concentration 1500 mg / liter) 500.
ml was returned to the raw water by 5 ml / hr. The results are shown in Table 1.
【００１０】[0010]
【表１】 [Table 1]
【００１１】[0011]
【発明の効果】本発明方法によると、フッ素含有水を、
そのフッ素濃度が変動しても安定して高度に処理するこ
とができ、水質の良好な処理水が得られるとともに、フ
ッ素を再資源化可能な高純度のフッ化カルシウムとして
効率よく回収することができる。According to the method of the present invention, the water containing fluorine is
Even if the fluorine concentration fluctuates, it can be stably treated at a high level, and treated water with good water quality can be obtained, and fluorine can be efficiently recovered as high-purity calcium fluoride that can be recycled. it can.
【図１】図１は本発明方法を実施するための１例の説明
図である。FIG. 1 is an explanatory view of an example for carrying out the method of the present invention.
【符号の説明】 １ フッ素含有廃水 ２ 原水槽 ３ 原水ポンプ ４ 粒状炭酸カルシウム充填塔 ５ フッ素吸着剤充填塔 ６ 再生液貯槽 ７ ポンプ ８ 再生廃液貯槽 ９ ポンプ[Explanation of symbols] 1 Fluorine-containing wastewater 2 raw water tank 3 Raw water pump 4 Granular calcium carbonate packed tower 5 Fluorine adsorbent packing tower 6 Regeneration liquid storage tank 7 pumps 8 Recycled waste liquid storage tank 9 pumps
───────────────────────────────────────────────────── フロントページの続き (72)発明者 佐藤 伸 東京都新宿区西新宿３丁目４番７号 栗 田工業株式会社内 (72)発明者 高土居 忠 東京都新宿区西新宿３丁目４番７号 栗 田工業株式会社内 (72)発明者 三木 正博 大阪府大阪市阿倍野区帝塚山一丁目23番 14−521 (72)発明者 福留 敏郎 大阪府南河内郡千早赤阪村大字小吹68− 335 (72)発明者 前野 又五郎 大阪府和泉市光明台２−42−６ (56)参考文献 特開 昭50−127872（ＪＰ，Ａ) 特開 昭54−7762（ＪＰ，Ａ) 特開 昭50−10798（ＪＰ，Ａ) 特開 昭54−121561（ＪＰ，Ａ) 特開 昭60−166083（ＪＰ，Ａ) 特開 昭60−166084（ＪＰ，Ａ) 特開 昭60−48191（ＪＰ，Ａ) 特開 平３−118897（ＪＰ，Ａ) 特開 昭50−142496（ＪＰ，Ａ) 特開 昭60−102992（ＪＰ，Ａ) 特開 平２−99189（ＪＰ，Ａ) 米国特許3551332（ＵＳ，Ａ) ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Shin Sato Chestnuts 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Tako Co., Ltd. (72) Inventor Tadashi Takadoi Chestnuts 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Tako Co., Ltd. (72) Inventor Masahiro Miki 1-23, Tezukayama, Abeno-ku, Osaka-shi, Osaka Prefecture 14-521 (72) Inventor Toshiro Fukudome Osaka Prefecture Minamikawachi-gun Chihaya Akasaka-mura Obi 68- 335 (72) Inventor Magoro Maeno 2-42-6 Komitsudai, Izumi City, Osaka Prefecture (56) Reference JP-A-50-127872 (JP, A) JP 54-7762 (JP, A) Japanese Patent Laid-Open No. 50-10798 (JP, A) JP 54-121561 (JP, A) JP 60-166083 (JP, A) JP 60-166084 (JP, A) JP-A-60-48191 (JP, A) JP-A-3-118897 (JP, A) JP-A-50-142496 (JP, A) JP-A-60-102992 (JP, A) JP-A-2-99189 (JP, A) US Patent 3551332 (US, A)
Claims (2)
を平均粒径０.１〜０.５mmの粒状炭酸カルシウム充填塔
に通水したのち、フッ素イオンと錯化合物を形成しうる
金属イオンを吸着した樹脂であるフッ素吸着剤充填塔に
通水してフッ化水素及びフッ化アンモニウム含有水を処
理する工程において、該フッ素吸着剤充填塔に再生液を
注入し、該フッ素吸着剤充填塔から排出される再生廃液
を粒状炭酸カルシウム充填塔の前段のフッ素含有水に加
え、再資源として利用可能な高純度フッ化カルシウムを
粒状炭酸カルシウム充填塔から間欠的又は連続的に回収
することを特徴とするフッ化水素及びフッ化アンモニウ
ム含有水の処理方法。1. Water containing hydrogen fluoride and ammonium fluoride is passed through a granular calcium carbonate packed column having an average particle size of 0.1 to 0.5 mm, and then metal ions capable of forming a complex compound with fluorine ions are adsorbed. In the step of treating hydrogen fluoride and ammonium fluoride-containing water by passing the resin through a fluorine adsorbent packed tower, the regenerant is injected into the fluorine adsorbent packed tower and discharged from the fluorine adsorbent packed tower. Characterized in that the regenerated waste liquid is added to the fluorine-containing water in the preceding stage of the granular calcium carbonate packed tower, and high-purity calcium fluoride that can be used as a resource is intermittently or continuously recovered from the granular calcium carbonate packed tower. A method for treating water containing hydrogen fluoride and ammonium fluoride.
ち、固液分離して、該フッ素吸着剤充填塔に通水してフ
ッ化水素及びフッ化アンモニウム含有水を処理すること
を特徴とする請求項１記載のフッ化水素及びフッ化アン
モニウム含有水の処理方法。2. A method comprising: passing water through the granular calcium carbonate packed tower, then performing solid-liquid separation, and passing through the fluorine adsorbent packed tower to treat water containing hydrogen fluoride and ammonium fluoride. The method for treating water containing hydrogen fluoride and ammonium fluoride according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24862592A JP3466646B2 (en) | 1992-08-25 | 1992-08-25 | Method of treating water containing hydrogen fluoride and ammonium fluoride |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24862592A JP3466646B2 (en) | 1992-08-25 | 1992-08-25 | Method of treating water containing hydrogen fluoride and ammonium fluoride |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0663563A JPH0663563A (en) | 1994-03-08 |
| JP3466646B2 true JP3466646B2 (en) | 2003-11-17 |
Family
ID=17180902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24862592A Expired - Lifetime JP3466646B2 (en) | 1992-08-25 | 1992-08-25 | Method of treating water containing hydrogen fluoride and ammonium fluoride |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3466646B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6720437B2 (en) | 2001-02-07 | 2004-04-13 | E. I. Du Pont De Nemours And Company | Fluorinated carboxylic acid recovery and reuse |
| CN114605018B (en) * | 2022-02-04 | 2024-02-02 | 重庆大学 | Method for treating phosphorus-containing fluorine-containing high-salt organic wastewater and recovering salt |
-
1992
- 1992-08-25 JP JP24862592A patent/JP3466646B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0663563A (en) | 1994-03-08 |
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