JP3653921B2 - Fluorine-containing water treatment method - Google Patents
Fluorine-containing water treatment method Download PDFInfo
- Publication number
- JP3653921B2 JP3653921B2 JP06081797A JP6081797A JP3653921B2 JP 3653921 B2 JP3653921 B2 JP 3653921B2 JP 06081797 A JP06081797 A JP 06081797A JP 6081797 A JP6081797 A JP 6081797A JP 3653921 B2 JP3653921 B2 JP 3653921B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- fluorine
- circulation tank
- contact
- circulation
- 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 - Fee Related
Links
Images
Landscapes
- Removal Of Specific Substances (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明はフッ素含有水の処理方法に係り、特にフッ素含有水を炭酸カルシウム（ＣａＣＯ３）粒子と接触させて、フッ素（Ｆ）をフッ化カルシウム（ＣａＦ２）として固定する方法において、ＣａＣＯ３粒子の崩壊を防止して、低Ｆ濃度で濁度の低い高水質処理水を得る方法に関する。
【０００２】
【従来の技術】
半導体製造分野やその関連分野、各種金属材料、単結晶材料、光学系材料等の表面処理分野では、フッ化水素（ＨＦ）やフッ化アンモニウム（ＮＨ４Ｆ）を主成分とするエッチング剤が多量に使用され、フッ素を含む排水が排出される。
【０００３】
このようなフッ素含有水の処理方法として、フッ素含有水をＣａＣＯ３充填塔に通水し、ＦをＣａＦ２として除去ないし回収する方法がある。また、この方法において、処理水水質の向上及び回収ＣａＦ２純度の向上を目的として、図２に示す如く、複数のＣａＣＯ３充填塔１１，１２，１３…を多段に配置し、各充填塔毎に流出水を循環させて順次後段のＣａＣＯ３充填塔に通水する方法が提案されている。
【０００４】
即ち、図２の方法において、原水槽１０内の原水をポンプＰ１により第１循環槽２１に送り、該第１循環槽２１内の原水を第１充填塔１１に循環通水する。第１循環槽２１のオーバーフロー水を第２循環槽２２に移流させ、この第２循環槽２２内の水を第２充填塔１２に循環通水する。この第２循環槽２２のオーバーフロー水を第３循環槽２３に移流させ、この第３循環槽２３内の水を第３充填塔１３に循環通水し、この最後段の循環槽２３のオーバーフロー水を処理水とする。
【０００５】
また、このような方法において、濾材（ＣａＣＯ３粒子）の崩壊による処理水の濁度の増加を防止する目的で、次のような改良法が提案されている。
<1> 原水のα値（Ｆ濃度に対する全酸濃度の当量比。この値が低いほど酸性度が高い 。）が所定の範囲となるように調整する方法（特開平７−９６２８５号公報）
<2> 循環槽で曝気を行って、濁度発生の原因となるＣＯ２を空気中に放出させる方法 （特開平７−１３６６６７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>，<2>の方法によっても、ＣａＣＯ３粒子の崩壊は十分には防止できない。
【０００７】
即ち、上記<1>の方法では、濁度が殆ど発生しないようにするために多量のアルカリを添加する必要があるが、アルカリを多量に添加するとＦ除去率が低下して処理水のＦ濃度が高くなるため、アルカリ添加量には制限があり、濁度の低減にも制約がある。
【０００８】
<2>の方法では、ｐＨ領域が中性付近の場合、水中のＣＯ２成分の多くは炭酸イオンとなっているためＣＯ２を十分に除去することはできず、やはり、濁度を十分に低減することはできない。
【０００９】
本発明は上記従来の問題点を解決し、フッ素含有水をＣａＣＯ３粒子と接触させてＦをＣａＦ２として固定する方法において、Ｆ濃度及び濁度が共にきわめて低い高水質処理水を得る方法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
本発明のフッ素含有水の処理方法は、循環タンク及び該循環タンクから水が循環通水される複数の接触塔を有した処理装置によって、所定量のフッ素含有水を炭酸カルシウム粒子と接触させてフッ素をフッ化カルシウムとして固定するフッ素含有水の処理方法において、接触開始時のｐＨを４以下とすると共に、接触開始時の炭酸カルシウム粒子の量を、通水されるフッ素含有水の総量中のフッ素量の１〜２当量とし、次の (i) 〜 (iv) よりなる第１バッチ処理工程
(i) 所定量のフッ素含有水を該循環タンクに導入する工程、
(ii) 一部の接触塔に炭酸カルシウム粒子を、該炭酸カルシウム粒子の全体量がこ の導入された水に含まれるフッ素量の１〜２当量となるように供給する工程、
(iii) 該一部の接触塔への循環タンク内の水の循環通水を開始すると共に、この 循環通水の間に他の接触塔内から反応済の粒子を取り出す工程、及び
(iv) 循環通水後に処理水を取り出す工程、
を行い、次いで次の (v) 〜 (viii) よりなる第２バッチ処理工程
(v) 所定量のフッ素含有水を該循環タンクに導入する工程、
(vi) 前記他の接触塔に炭酸カルシウム粒子を、該炭酸カルシウム粒子の全体量が この導入された水に含まれるフッ素量の１〜２当量となるように供給する工程 、
(vii) 該他の接触塔への循環タンク内の水の循環通水を開始すると共に、この循 環通水の間に前記一部の接触塔内から反応済の粒子を取り出す工程、及び
(viii) 循環通水後に処理水を取り出す工程、
を行い、その後該第１バッチ処理工程と、第２バッチ処理工程とを繰り返すフッ素含有水の処理方法であって、
前記第１又は第２バッチ処理工程後に第２又は第１バッチ処理工程を行う場合、新たに循環槽に導入されたフッ素含有水を新たに炭酸カルシウム粒子が供給された接触塔に通水開始するに先立って、まだ反応済の粒子が取り出されていない接触塔に該循環槽内のフッ素含有水を所定時間循環通水し、その後、この循環槽内の水を該新たに炭酸カルシウム粒子が供給された接触塔に通水開始することを特徴とする。
【００１１】
本発明者は、前記<1>，<2>の方法においてＣａＣＯ３濾材の崩壊による濁度増加を十分には防止し得ないのは、排水中のｐＨが不適切（中性ないしアルカリ域）であると共に、ＣａＣＯ３量が全負荷Ｆ量よりも大過剰であるためであるとの知見を得た。
【００１２】
即ち、従来においては、ＣａＣＯ３充填塔に大過剰当量のＣａＣＯ３が充填されているため、下記(I)式のＣａＣＯ３とＦとの反応（酸を消費する。）が急速に進行し、通水される被処理水のｐＨが中性ないしアルカリ性となる。このため、ＣａＣＯ３とＦとの反応（下記(I)式）で発生するＣＯ２は直ちにＣａＣＯ３粒子表面付近で下記(II)式の如く電離する。
ＣａＣＯ３＋２Ｆ−＋２Ｈ＋→ ＣａＦ２＋ＣＯ２＋Ｈ２Ｏ …… (I)
ＣＯ２＋Ｈ２Ｏ → Ｈ＋＋ＨＣＯ３ − …… (II)
【００１３】
このＣＯ２の電離で生成するＨ＋＋ＨＣＯ３ −が濾材のＣａＣＯ３の一部を溶解させ、溶解したＣａ２＋は水中のＦ−と液相中で反応してＣａＦ２を生成する。この液相中で生成したＣａＦ２が濁度成分となって、処理水の濁度を高める。
【００１４】
そこで、本発明では、接触開始時のｐＨを４以下とすると共に、ＣａＣＯ３粒子をフッ素含有水中のＦの１〜２当量と少なくする。
【００１５】
このようにＣａＣＯ３とＦとの反応を低ｐＨ領域で開始させ、且つＣａＣＯ３当量をＦと当量ないし小過剰量にすることにより、上記(I) 式の反応速度が小さくなり、ＣＯ２生成速度が小さくなると共に、Ｈ＋の消費速度が小さくなり、被処理水のｐＨが長期にわたって酸性に維持されるようになる。このようにして、ＣＯ２の生成量が少なくなると共にＣＯ２の電離も著しく抑制されるようになり、ＣａＣＯ３とＦとの反応で発生したＣＯ２は、発生と同時にＣＯ２ガスとして空気中に放出される。このため、ＣａＣＯ３の溶解によるＣａ２＋とＦ−との液相での反応が抑制され、濁度成分の生成が抑制される。
【００１６】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態を説明する。
【００１７】
図１は本発明のフッ素含有水の処理方法の実施の形態を示す系統図である。
【００１８】
図示の方法では、２個の接触塔を用い、次のように第１バッチ処理工程と第２バッチ処理工程とを交互に繰り返して処理を行う。
【００１９】
［第１バッチ処理工程］
(1)まず、原水槽１内の原水の所定量（Ｖ１）を循環タンク２に移送する。
(2)ポンプＰで循環タンク２内の水を第１接触塔３に導入し、第１接触塔３と循環タンク ２の循環系路に循環させる。
(3)Ｆ計（フッ素濃度計）２Ａで循環タンク２内の水のＦ濃度（ｃ１）を測定し、Ｖ１× ｃ１で求まる総Ｆ量の１〜２当量相当のＣａＣＯ３粒子をＣａＣＯ３添加手段５より第 １接触塔３に投入し、その後原水を所定時間循環させた後、循環タンク２に戻す。
(4)循環タンク２内の水を処理水として系外へ排出する。
［第２バッチ処理工程］
(5)再び原水槽１内の原水を所定量（Ｖ２）循環タンク２に移送し、上記(2) と同様に第 １接触塔３〜循環タンク２に所定時間循環させた後、循環タンク２に戻し循環を停止す る。この操作で第１接触塔３内においてＣａＣＯ３とＦとの反応で生成するＣａＦ２の 純度を高めることができる。
(6)循環タンク２内の水をポンプＰで第２接触塔４に導入し、第２接触塔４と循環タンク ２の循環系路に循環させる。
(7)Ｆ計２Ａで循環タンク２内の水のＦ濃度（ｃ２）を測定し、Ｖ２×ｃ２で求まる総Ｆ 量の１〜２当量相当のＣａＣＯ３粒子をＣａＣＯ３添加手段５より第２接触塔４に投 入し、その後更に所定時間循環させた後、循環タンク２に戻す。
（上記(6),(7)の間に第１接触塔３内のＣａＦ２粒子を抜き出す。）
(8)循環タンク２内の水を処理水として系外へ排出する。
［再度の第１バッチ処理工程］
(9)再度原水槽１内の原水を循環タンク２に移送し、上記(5) と同様に第２接触塔４〜循 環タンク２に所定時間循環させた後、循環を停止する。この操作で第２接触塔４内にお いてＣａＣＯ３とＦとの反応で生成するＣａＦ２の純度を高めることができる。
(10)循環タンク２内の水をポンプＰで第１接触塔３に導入し、上記(2) と同様に第１接触 塔３〜循環タンク２に循環させ、上記(3) と同様にＦ濃度測定、ＣａＣＯ３粒子添加を 行い、所定時間循環後停止する。
【００２０】
この間に第２接触塔４内のＣａＦ２粒子を抜き出し、以後同様に再度の第２バッチ処理工程と再度の第１バッチ処理工程とを繰り返し、第１接触塔３、第２接触塔４で交互に処理を行う。
【００２１】
本発明において、ＣａＣＯ３粒子との接触開始時のフッ素含有水のｐＨが４を超えると、ｐＨが高過ぎるため反応で生成したＣＯ２が効率的に空気中に放出されず、濾材の崩壊で濁度が発生する。従って、被処理フッ素含有水のｐＨが４を超える場合には、硫酸・塩酸等の酸を添加してｐＨを４以下好ましくは１．５〜４とくに１．０〜３．０に調整する。
【００２２】
なお、反応系のｐＨは、反応の進行に伴い高くなっていくが、本発明では、接触開始から３時間後までの反応初期において、ｐＨを５．０以下、好ましくは４．０〜４．５に維持するのが好ましい。
【００２３】
また、ＣａＣＯ３粒子の割合がフッ素含有水中のＦの２当量を超えると反応系内が中性〜アルカリ側となり、ＣＯ２が電離することにより濁度成分（液相中で生成するＣａＦ２）が発生するおそれがある。一方、ＣａＣＯ３粒子の割合がフッ素含有水中のＦの１当量未満であると当然ながら排水中のＦ除去が不十分となる。従って、ＣａＣＯ３粒子はフッ素含有水中のＦに対して１〜２当量好ましくは１．３〜１．５当量となるようにする。
【００２４】
なお、このＣａＣＯ３粒子の平均粒径は、反応効率や取り扱い性の面から０．１〜１．０ｍｍとくに０．２〜０．３ｍｍであることが好ましい。
【００２５】
この実施の形態に係る方法によれば、濁度の発生を著しく低く抑えることができると共に、高純度のＣａＦ２を回収することができる。また、ＣａＣＯ３の添加量が少ないため、ＣａＣＯ３粒子の圧密化による粒子同士の固着も防止され、効率的な処理を行える。
【００２６】
水中にＨＦ以外の酸（酢酸や硝酸など）を含まない場合には、前記<1>の方法のようにα値の調整も不要である。そして、アルカリの添加が不要であることによって、処理水のＦ濃度はより一層低減される。
【００２７】
なお、排水の分別を高度に行ってＦ濃度の高い原水を処理するようにすることにより、装置をコンパクト化することができる。
【００２８】
図１に示す方法は本発明の実施に好適な方法の一例であって、本発明は何ら図示の方法に限定されるものではない。例えば、接触塔は３塔以上の複数配置して行うことも可能である。接触塔は充填塔であっても良く、流動床などであっても良い。
【００２９】
【実施例】
以下に実験例、実施例及び比較例を挙げて本発明をより具体的に説明する。なお、この実験例、実施例及び比較例で用いたＣａＣＯ３
粒子は石灰石粒子である。
【００３０】
実験例１
容器にＦ濃度２０００ｍｇ／Ｌ、ｐＨ２．５のＨＦ水溶液１００Ｌを入れ、撹拌しながら、粒径０．３ｍｍのＣａＣＯ３粒子をＦに対して１．５、２．０、３．０又は１０当量（０．７９、１．０５、１．５８又は５．２６ｋｇ）添加した。０．５，１，３又は６時間経過する毎に撹拌を一時止めて静置し、３０秒後に上澄水をサンプリングしてそのＦ濃度、ｐＨ、濁度を測定し、結果を表１に示した。
【００３１】
【表１】
表１より次のことが明らかである。
【００３３】
ＣａＣＯ３をＦに対して１．５又は２当量添加したＮｏ．１，２の場合では、長時間にわたり反応が低ｐＨ領域で進み、濁度は極めて低い。これに対して、Ｎｏ．３，４では、大過剰のＣａＣＯ３が存在し、反応当初からｐＨが高い領域で反応が進み、反応当初から濁度が極めて高い。
【００３４】
実施例１
図１に示す装置により、下記の手順でＨＦ水溶液（Ｆ濃度２０００ｍｇ／Ｌ，ｐＨ２．５）の処理を行った。
【００３５】
(1)原水槽１内の原水２００Ｌを循環タンク２に移送した。
(2)ポンプＰで循環タンク２内の水を第１接触塔（２０Ｌ容量）３〜循環タンク２に循環
させた。
(3)Ｆ計２Ａで循環タンク２内の水のＦ濃度を測定したところ２０００ｍｇ／Ｌのままで あるので、Ｆ量の１．５当量相当の１．５８ｋｇのＣａＣＯ３粒子（平均粒径０．３ｍ ｍ）をＣａＣＯ３添加手段５より第１接触塔３に投入し、更に６ｈｒ循環させた後、循 環を停止した。
(4)循環タンク２内の水を処理水として排出した。
(5)再び原水槽１内の原水２００Ｌを循環タンク２に移送し、第１接触塔３〜循環タンク ２に６ｈｒ循環させた後、循環を停止した。
(6)循環タンク２内の水をポンプＰで第２接触塔（２０Ｌ容量）４〜循環タンク２に循環 させた。なお、この水のｐＨは３．４であった。
(7)Ｆ計２Ａで循環タンク２内の水のＦ濃度を測定したところ１１００ｍｇ／Ｌであった ので、Ｆ量の１．５当量相当の０．８７ｋｇのＣａＣＯ３粒子をＣａＣＯ３添加手段 ５より第２接触塔４に投入し、更に６ｈｒ循環させた後、循環を停止した。
（上記(6)，(7)の間に第１接触塔３内のＣａＦ２粒子を抜き出した。）
(8)循環タンク２内の水を処理水として排出した。
(9)再度原水槽１内の原水２００Ｌを循環タンク２に移送し、第２接触塔４〜循環タンク ２に６ｈｒ循環させた後、循環を停止した。
(10)循環タンク２内の水をポンプＰで第１接触塔３〜循環タンク２に循環させた。
(11)上記(3)と同様にＦ濃度を測定したところ１６００ｍｇ／Ｌであったので、１．５ 当量（１．２６ｋｇ）のＣａＣＯ３粒子添加を行い、６ｈｒ循環後停止した。この間に 第２接触塔４内のＣａＦ２粒子を抜き出し、以後同様の操作を繰り返し、第１接触塔３ ，第２接触塔４で交互に処理を行った。
【００３６】
このようにして原水２０００Ｌを処理したときの処理水の平均水質（Ｆ濃度，ｐＨ，濁度）を調べ、結果を表２に示した。また、抜き出したＣａＦ２粒子のＣａＦ２純度を調べ、結果を表２に示した。
【００３７】
比較例１
図２に示す従来法で実施例１の原水と同様のＨＦ水溶液（Ｆ濃度２０００ｍｇ／Ｌ，ｐＨ２．５）を原水として処理を行った。
【００３８】
各充填塔（２０Ｌ容量）１１〜１３には、各々、ＣａＣＯ３粒子（粒径０．３ｍｍ）を５ｋｇ充填した。また、各循環槽（２０Ｌ容量）２１〜２３では散気管により曝気を行った。原水処理量は２０ｍＬ／ｈｒとし、各々循環槽２１〜２３と充填塔１１〜１３とを２０ｍＬ／ｍｉｎで循環させて処理を行い、各々の循環槽のオーバーフロー水を後段の循環槽に送り、循環槽２３のオーバーフロー水を処理水として得た。
【００３９】
このようにして原水２０００Ｌを処理したときの処理水の平均水質（Ｆ濃度，ｐＨ，濁度）を調べ、結果を表２に示した。また、抜き出したＣａＦ２粒子のＣａＦ２純度を調べ、結果を表２に示した。
【００４０】
比較例２
比較例１において、原水にＮａＯＨをＨＦの０．３当量分添加したこと以外は同様に処理を行い、得られた処理水の水質及びＣａＦ２粒子の純度を表２に示した。
【００４１】
【表２】
表２より明らかなように、本発明の方法によれば、Ｆ濃度が低く濁度も著しく低い高水質処理水を得ることができ、ＣａＦ２の回収純度も高い。これに対して、原水にアルカリを添加した比較例２では、Ｆ濃度、濁度共に高く、循環水の曝気のみを行った比較例１では、Ｆ濃度は低いが濁度が高過ぎて後処理が煩雑となる。
【００４３】
【発明の効果】
以上詳述した通り、本発明のフッ素含有水の処理方法によれば、Ｆ濃度が低く、しかも濁度が著しく低い高水質処理水を得ることができる。このため、本発明によれば、後段の処理を軽減することができる。
【図面の簡単な説明】
【図１】 本発明のフッ素含有水の処理方法の実施の形態を示す系統図である。
【図２】 従来法を示す系統図である。
【符号の説明】
１ 原水槽
２ 循環タンク
３ 第１接触塔
４ 第２接触塔
５ ＣａＣＯ３添加手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of treating fluorine-containing water, in particular a fluorine-containing water calcium carbonate (CaCO 3) is contacted with particles, fluorine (F) in the method of fixing as calcium fluoride (CaF 2), CaCO 3 particles It is related with the method of obtaining the high-quality treated water with a low F concentration and low turbidity by preventing the collapse of water.
[0002]
[Prior art]
In the field of semiconductor manufacturing and related fields, various metal materials, single crystal materials, optical system materials, etc., surface treatment fields such as hydrogen fluoride (HF) and ammonium fluoride (NH 4 F) are used in large quantities. Wastewater containing fluorine is discharged.
[0003]
As a method for treating such fluorine-containing water, there is a method in which fluorine-containing water is passed through a CaCO 3 packed tower and F is removed or recovered as CaF 2 . In this method, for the purpose of improving the quality of treated water and improving the purity of recovered CaF 2 , a plurality of CaCO 3 packed
[0004]
That is, in the method of FIG. 2, the raw water in the raw water tank 10 is sent to the
[0005]
Moreover, in such a method, the following improved methods have been proposed for the purpose of preventing an increase in the turbidity of treated water due to the collapse of the filter medium (CaCO 3 particles).
<1> Method for adjusting the α value of raw water (equivalent ratio of total acid concentration to F concentration; the lower the value, the higher the acidity) to be within a predetermined range (Japanese Patent Laid-Open No. 7-96285)
<2> A method in which aeration is performed in a circulation tank and CO 2 causing turbidity is released into the air (Japanese Patent Laid-Open No. 7-136667)
[0006]
[Problems to be solved by the invention]
However, even by the methods <1> and <2> , the collapse of CaCO 3 particles cannot be sufficiently prevented.
[0007]
That is, in the above method <1> , it is necessary to add a large amount of alkali so that turbidity hardly occurs. However, if a large amount of alkali is added, the F removal rate decreases and the F concentration of treated water is reduced. Therefore, there is a limit to the amount of alkali added, and there is a limit to the reduction of turbidity.
[0008]
In the method <2> , when the pH region is near neutral, most of the CO 2 components in the water are carbonate ions, so CO 2 cannot be removed sufficiently. It cannot be reduced.
[0009]
The present invention solves the above-mentioned conventional problems, and in a method of fixing fluorine as CaF 2 by bringing fluorine-containing water into contact with CaCO 3 particles, a method for obtaining high-quality water having both extremely low F concentration and turbidity. The purpose is to provide.
[0010]
[Means for Solving the Problems]
In the method for treating fluorine-containing water of the present invention , a predetermined amount of fluorine-containing water is brought into contact with calcium carbonate particles by a treatment device having a circulation tank and a plurality of contact towers through which water is circulated. In the method for treating fluorine-containing water in which fluorine is fixed as calcium fluoride, the pH at the start of contact is set to 4 or less, and the amount of calcium carbonate particles at the start of contact is determined based on the total amount of fluorine-containing water to be passed. The first batch processing step consisting of the following (i) to (iv) with 1 to 2 equivalents of fluorine amount
(i) introducing a predetermined amount of fluorine-containing water into the circulation tank;
(ii) a portion of the calcium carbonate particles in contact column, feeding as the total amount of the calcium carbonate particles is 1-2 equivalent of the fluorine content in the water introduced in this,
(iii) starting circulation of water in the circulation tank to the partial contact tower , and taking out reacted particles from the other contact tower during the circulation water; and
(iv) a step of removing treated water after circulating water;
And then the second batch processing step comprising the following (v) to (viii)
(v) introducing a predetermined amount of fluorine-containing water into the circulation tank;
(vi) supplying the calcium carbonate particles to the other contact tower so that the total amount of the calcium carbonate particles is 1 to 2 equivalents of the amount of fluorine contained in the introduced water ;
(vii) steps taken starts the circulation water passage of the water in the circulation tank to said other contact tower, the reaction completion particles from the part of the contact tower during the circulation water flow and,
(viii) a step of removing treated water after circulating water;
And then processing the fluorine-containing water by repeating the first batch processing step and the second batch processing step,
When the second or first batch processing step is performed after the first or second batch processing step, the fluorine-containing water newly introduced into the circulation tank is started to flow into the contact tower newly supplied with calcium carbonate particles. Prior to this, the fluorine-containing water in the circulation tank is circulated for a predetermined time to the contact tower from which the reacted particles have not yet been taken out, and then the water in the circulation tank is supplied by the new calcium carbonate particles. It is characterized by starting water flow through the contact tower .
[0011]
The present inventor cannot prevent the increase in turbidity due to the collapse of the CaCO 3 filter medium in the above methods <1> and <2> because the pH in the wastewater is inappropriate (neutral or alkaline range). In addition, the present inventors have found that the amount of CaCO 3 is larger than the total load F amount.
[0012]
That is, conventionally, since a large excess equivalent amount of CaCO 3 is packed in the CaCO 3 packed column, the reaction (causing acid) of CaCO 3 and F of the following formula (I) proceeds rapidly, The pH of the water to be treated to be passed becomes neutral or alkaline. For this reason, CO 2 generated by the reaction between CaCO 3 and F (the following formula (I)) is immediately ionized near the surface of the CaCO 3 particles as shown in the following formula (II).
CaCO 3 + 2F − + 2H + → CaF 2 + CO 2 + H 2 O (I)
CO 2 + H 2 O → H + + HCO 3 − (II)
[0013]
The H + + HCO 3 − generated by the ionization of CO 2 dissolves a part of the filter medium CaCO 3 , and the dissolved Ca 2+ reacts with F − in water in the liquid phase to generate CaF 2 . CaF 2 generated in the liquid phase becomes a turbidity component, increasing the turbidity of the treated water.
[0014]
Therefore, in the present invention, the pH at the start of contact is set to 4 or less, and the CaCO 3 particles are reduced to 1 to 2 equivalents of F in the fluorine-containing water.
[0015]
Thus, by starting the reaction between CaCO 3 and F in a low pH region and making CaCO 3 equivalents equivalent to F or a small excess, the reaction rate of the above formula (I) is reduced, and CO 2 production is reduced. As the rate decreases, the consumption rate of H + decreases, and the pH of the water to be treated is maintained acidic over a long period of time. In this way, the amount of CO 2 produced is reduced and the ionization of CO 2 is remarkably suppressed, and CO 2 generated by the reaction of CaCO 3 and F is simultaneously generated as CO 2 gas in the air. To be released. Thus, Ca 2+ and F due to the dissolution of CaCO 3 - reaction between the liquid phase is suppressed, generation of turbidity component is suppressed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
FIG. 1 is a system diagram showing an embodiment of a method for treating fluorine-containing water according to the present invention.
[0018]
In the illustrated method, two contact towers are used, and processing is performed by alternately repeating the first batch processing step and the second batch processing step as follows.
[0019]
[First batch processing step]
(1) First, a predetermined amount (V 1 ) of raw water in the raw water tank 1 is transferred to the circulation tank 2.
(2) The water in the circulation tank 2 is introduced into the first contact tower 3 by the pump P and is circulated through the circulation path between the first contact tower 3 and the circulation tank 2.
(3) The F concentration (c 1 ) of the water in the circulation tank 2 is measured with an F meter (fluorine concentration meter) 2A, and CaCO 3 particles corresponding to 1 to 2 equivalents of the total F amount obtained by V 1 × c 1 are obtained. The CaCO 3 addition means 5 is charged into the first contact tower 3 and then the raw water is circulated for a predetermined time and then returned to the circulation tank 2.
(4) The water in the circulation tank 2 is discharged out of the system as treated water.
[Second batch processing step]
(5) The raw water in the raw water tank 1 is again transferred to the predetermined amount (V 2 ) circulation tank 2 and circulated through the first contact tower 3 to the circulation tank 2 for a predetermined time in the same manner as (2) above. Return to 2 to stop circulation. By this operation, the purity of CaF 2 produced by the reaction between CaCO 3 and F in the first contact tower 3 can be increased.
(6) Water in the circulation tank 2 is introduced into the second contact tower 4 by the pump P and is circulated through the circulation system path of the second contact tower 4 and the circulation tank 2.
(7) The F concentration (c 2 ) of the water in the circulation tank 2 is measured with the
(CaF 2 particles in the first contact tower 3 are extracted between the above (6) and (7).)
(8) The water in the circulation tank 2 is discharged out of the system as treated water.
[First batch processing step again]
(9) The raw water in the raw water tank 1 is transferred again to the circulation tank 2 and is circulated through the second contact tower 4 to the circulation tank 2 for a predetermined time in the same manner as ( 5 ) above, and then the circulation is stopped. By this operation, the purity of CaF 2 produced by the reaction between CaCO 3 and F in the second contact tower 4 can be increased.
(10) Water in the circulation tank 2 is introduced into the first contact tower 3 by the pump P and circulated to the first contact tower 3 to the circulation tank 2 in the same manner as (2) above, and F in the same manner as in (3) above. Concentration measurement, addition of CaCO 3 particles, and stop after circulation for a predetermined time.
[0020]
During this time, the CaF 2 particles in the second contact tower 4 are extracted, and thereafter the second batch treatment step and the first batch treatment step are repeated in the same manner, and alternately in the first contact tower 3 and the second contact tower 4. To process.
[0021]
In the present invention, when the pH of the fluorine-containing water at the start of contact with the CaCO 3 particles exceeds 4, the pH is too high, so that the CO 2 produced by the reaction is not efficiently released into the air, and the filter medium collapses. Turbidity occurs. Accordingly, when the pH of the fluorine-containing water to be treated exceeds 4, an acid such as sulfuric acid / hydrochloric acid is added to adjust the pH to 4 or less, preferably 1.5 to 4, particularly 1.0 to 3.0.
[0022]
The pH of the reaction system increases with the progress of the reaction, but in the present invention, the pH is 5.0 or less, preferably 4.0-4. 5 is preferably maintained.
[0023]
Further, when the ratio of CaCO 3 particles exceeds 2 equivalents of F in fluorine-containing water, the reaction system becomes neutral to alkali side, and CO 2 is ionized to cause turbidity components (CaF 2 generated in the liquid phase). May occur. On the other hand, if the proportion of CaCO 3 particles is less than 1 equivalent of F in fluorine-containing water, naturally, removal of F in the wastewater will be insufficient. Accordingly, the CaCO 3 particles are adjusted to 1 to 2 equivalents, preferably 1.3 to 1.5 equivalents, with respect to F in the fluorine-containing water.
[0024]
In addition, the average particle diameter of the CaCO 3 particles is preferably 0.1 to 1.0 mm, particularly preferably 0.2 to 0.3 mm from the viewpoint of reaction efficiency and handleability.
[0025]
According to the method according to this embodiment, the occurrence of turbidity can be remarkably reduced, and high-purity CaF 2 can be recovered. Further, since the amount of CaCO 3 added is small, the particles are prevented from sticking together due to consolidation of CaCO 3 particles, and an efficient treatment can be performed.
[0026]
When no acid other than HF (acetic acid, nitric acid, etc.) is contained in water, it is not necessary to adjust the α value as in the method <1> . And since the addition of an alkali is unnecessary, the F density | concentration of treated water is reduced further.
[0027]
Note that the apparatus can be made compact by performing high-level wastewater separation to treat raw water having a high F concentration.
[0028]
The method shown in FIG. 1 is an example of a method suitable for carrying out the present invention, and the present invention is not limited to the illustrated method. For example, the contact tower is also possible to perform a plurality arrangement of three or more towers. The contact tower may be a packed tower or a fluidized bed .
[0029]
【Example】
Hereinafter, the present invention will be described in more detail with reference to experimental examples, examples and comparative examples. In addition, CaCO3 used in these experimental examples, examples and comparative examples
The particles are limestone particles.
[0030]
Experimental example 1
In a container, 100 L of an HF aqueous solution having an F concentration of 2000 mg / L and a pH of 2.5 is added, and while stirring, CaCO 3 particles having a particle size of 0.3 mm are 1.5, 2.0, 3.0, or 10 equivalents to F. (0.79, 1.05, 1.58 or 5.26 kg) was added. Stirring is temporarily stopped every 0.5, 1, 3 or 6 hours, and after standing for 30 seconds, the supernatant water is sampled and its F concentration, pH and turbidity are measured, and the results are shown in Table 1. It was.
[0031]
[Table 1]
From Table 1, the following is clear.
[0033]
No. in which 1.5 or 2 equivalent of CaCO 3 was added to F. In the case of 1 and 2, the reaction proceeds in a low pH region over a long time, and the turbidity is extremely low. In contrast, no . In 3 and 4 , there is a large excess of CaCO 3 , the reaction proceeds in the region where the pH is high from the beginning of the reaction, and the turbidity is extremely high from the beginning of the reaction.
[0034]
Example 1
The apparatus shown in FIG. 1 was used to treat an HF aqueous solution (F concentration 2000 mg / L, pH 2.5) according to the following procedure.
[0035]
(1) 200 L of raw water in the raw water tank 1 was transferred to the circulation tank 2.
(2) The water in the circulation tank 2 was circulated to the first contact tower (20 L capacity) 3 to the circulation tank 2 by the pump P.
(3) When the F concentration of the water in the circulation tank 2 was measured with the
(4) The water in the circulation tank 2 was discharged as treated water.
(5) 200 L of raw water in the raw water tank 1 was again transferred to the circulation tank 2 and circulated through the first contact tower 3 to the circulation tank 2 for 6 hours, and then the circulation was stopped.
(6) The water in the circulation tank 2 was circulated by the pump P from the second contact tower (20 L capacity) 4 to the circulation tank 2. The pH of this water was 3.4.
(7) When the F concentration of water in the circulation tank 2 was measured with the
(CaF 2 particles in the first contact tower 3 were extracted between the above (6) and (7).)
(8) The water in the circulation tank 2 was discharged as treated water.
(9) 200 L of raw water in the raw water tank 1 was transferred again to the circulation tank 2 and circulated through the second contact tower 4 to the circulation tank 2 for 6 hours, and then the circulation was stopped.
(10) The water in the circulation tank 2 was circulated by the pump P to the first contact tower 3 to the circulation tank 2.
(11) When the F concentration was measured in the same manner as in (3) above, it was 1600 mg / L. Therefore, 1.5 equivalent (1.26 kg) of CaCO 3 particles was added, and the mixture was stopped after circulating for 6 hours. During this time, CaF 2 particles in the second contact tower 4 were extracted, and thereafter the same operation was repeated, and the first contact tower 3 and the second contact tower 4 were alternately processed.
[0036]
Thus, the average water quality (F density | concentration, pH, turbidity) at the time of processing 2000L of raw | natural water was investigated, and the result was shown in Table 2. Further, the CaF 2 purity of the extracted CaF 2 particles was examined, and the results are shown in Table 2.
[0037]
Comparative Example 1
The HF aqueous solution (F concentration 2000 mg / L, pH 2.5) similar to the raw water of Example 1 was treated using the conventional method shown in FIG. 2 as the raw water.
[0038]
Each packed tower (20 L capacity) 11 to 13 was filled with 5 kg of CaCO 3 particles (particle size 0.3 mm). Moreover, in each circulation tank (20L capacity | capacitance) 21-23, it aerated with the diffuser. The raw water treatment amount is 20 mL / hr, each of the
[0039]
The average water quality (F concentration, pH, turbidity) of the treated water when 2000 L of raw water was treated in this manner was examined, and the results are shown in Table 2. Further, the CaF 2 purity of the extracted CaF 2 particles was examined, and the results are shown in Table 2.
[0040]
Comparative Example 2
In Comparative Example 1, performs the same procedure except that the NaOH was 0.3 added an equivalent amount of HF in the raw water, the purity of water and CaF 2 particles treated water thus obtained are shown in Table 2.
[0041]
[Table 2]
As is clear from Table 2, according to the method of the present invention, high-quality water having a low F concentration and a remarkably low turbidity can be obtained, and the recovery purity of CaF 2 is also high. On the other hand, in Comparative Example 2 in which alkali was added to the raw water, both F concentration and turbidity were high, and in Comparative Example 1 in which only aeration of circulating water was performed, the F concentration was low but the turbidity was too high, and post-treatment Becomes complicated.
[0043]
【The invention's effect】
As described above in detail, according to the method for treating fluorine-containing water of the present invention, it is possible to obtain high-quality treated water having a low F concentration and extremely low turbidity. For this reason, according to the present invention, subsequent processing can be reduced.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a method for treating fluorine-containing water according to the present invention.
FIG. 2 is a system diagram showing a conventional method.
[Explanation of symbols]
1 raw water tank 2 circulation tank 3 first contact column 4 second contact column 5 CaCO 3 addition means
Claims (1)
接触開始時のｐＨを４以下とすると共に、接触開始時の炭酸カルシウム粒子の量を、通水されるフッ素含有水の総量中のフッ素量の１〜２当量とし、
次の (i) 〜 (iv) よりなる第１バッチ処理工程
(i) 所定量のフッ素含有水を該循環タンクに導入する工程、
(ii) 一部の接触塔に炭酸カルシウム粒子を、該炭酸カルシウム粒子の全体量がこ の導入された水に含まれるフッ素量の１〜２当量となるように供給する工程、
(iii) 該一部の接触塔への循環タンク内の水の循環通水を開始すると共に、この 循環通水の間に他の接触塔内から反応済の粒子を取り出す工程、及び
(iv) 循環通水後に処理水を取り出す工程、
を行い、次いで次の (v) 〜 (viii) よりなる第２バッチ処理工程
(v) 所定量のフッ素含有水を該循環タンクに導入する工程、
(vi) 前記他の接触塔に炭酸カルシウム粒子を、該炭酸カルシウム粒子の全体量が この導入された水に含まれるフッ素量の１〜２当量となるように供給する工程
、
(vii) 該他の接触塔への循環タンク内の水の循環通水を開始すると共に、この循 環通水の間に前記一部の接触塔内から反応済の粒子を取り出す工程、及び
(viii) 循環通水後に処理水を取り出す工程、
を行い、その後該第１バッチ処理工程と、第２バッチ処理工程とを繰り返すフッ素含有水の処理方法であって、
前記第１又は第２バッチ処理工程後に第２又は第１バッチ処理工程を行う場合、
新たに循環槽に導入されたフッ素含有水を新たに炭酸カルシウム粒子が供給された接触塔に通水開始するに先立って、まだ反応済の粒子が取り出されていない接触塔に該循環槽内のフッ素含有水を所定時間循環通水し、その後、この循環槽内の水を該新たに炭酸カルシウム粒子が供給された接触塔に通水開始することを特徴とするフッ素含有水の処理方法。Fluorine-containing water in which a predetermined amount of fluorine-containing water is brought into contact with calcium carbonate particles to fix fluorine as calcium fluoride by a treatment device having a circulation tank and a plurality of contact towers through which water is circulated from the circulation tank In the processing method of
The pH at the start of contact is 4 or less, and the amount of calcium carbonate particles at the start of contact is set to 1 to 2 equivalents of the amount of fluorine in the total amount of fluorine-containing water to be passed ,
The first batch processing step consisting of the following (i) to (iv)
(i) introducing a predetermined amount of fluorine-containing water into the circulation tank;
(ii) a portion of the calcium carbonate particles in contact column, feeding as the total amount of the calcium carbonate particles is 1-2 equivalent of the fluorine content in the water introduced in this,
(iii) starting circulation of water in the circulation tank to the partial contact tower , and taking out reacted particles from the other contact tower during the circulation water; and
(iv) a step of removing treated water after circulating water;
And then the second batch processing step comprising the following (v) to (viii)
(v) introducing a predetermined amount of fluorine-containing water into the circulation tank;
(vi) supplying the calcium carbonate particles to the other contact tower so that the total amount of the calcium carbonate particles is 1 to 2 equivalents of the amount of fluorine contained in the introduced water.
,
(vii) steps taken starts the circulation water passage of the water in the circulation tank to said other contact tower, the reaction completion particles from the part of the contact tower during the circulation water flow and,
(viii) a step of removing treated water after circulating water;
And then processing the fluorine-containing water by repeating the first batch processing step and the second batch processing step,
When performing the second or first batch processing step after the first or second batch processing step,
Prior to the start of passing the fluorine-containing water newly introduced into the circulation tank into the contact tower to which calcium carbonate particles have been newly supplied, the contact tower in which the reacted particles have not yet been removed is put into the circulation tank. A method for treating fluorine-containing water, wherein the fluorine-containing water is circulated for a predetermined time, and then the water in the circulation tank is started to pass through the contact tower to which calcium carbonate particles are newly supplied .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06081797A JP3653921B2 (en) | 1997-03-14 | 1997-03-14 | Fluorine-containing water treatment method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06081797A JP3653921B2 (en) | 1997-03-14 | 1997-03-14 | Fluorine-containing water treatment method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10249361A JPH10249361A (en) | 1998-09-22 |
| JP3653921B2 true JP3653921B2 (en) | 2005-06-02 |
Family
ID=13153294
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06081797A Expired - Fee Related JP3653921B2 (en) | 1997-03-14 | 1997-03-14 | Fluorine-containing water treatment method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3653921B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5440095B2 (en) * | 2009-10-22 | 2014-03-12 | 栗田工業株式会社 | Method and apparatus for treating fluorine-containing water |
-
1997
- 1997-03-14 JP JP06081797A patent/JP3653921B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10249361A (en) | 1998-09-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5275691A (en) | Method for treating a surface of an aluminum substrate for a printing plate | |
| JP3653921B2 (en) | Fluorine-containing water treatment method | |
| JP3334142B2 (en) | Treatment method for fluorine-containing water | |
| JPH1157773A (en) | Biological dephosphorizing device | |
| JP3483482B2 (en) | Fluorine-containing water treatment method | |
| JP4169996B2 (en) | Method and apparatus for treating fluorine-containing wastewater | |
| JP3238745B2 (en) | Method of treating ammonium fluoride-containing water | |
| JP3175445B2 (en) | Fluorine-containing water treatment method | |
| JP3697800B2 (en) | Wastewater treatment method | |
| EP0783461B1 (en) | Method for processing acid effluents | |
| JP3266309B2 (en) | Treatment method for acidic fluorine-containing water | |
| JPH0975925A (en) | Treatment of flue gas desulfurization waste water | |
| JP3175283B2 (en) | Fluorine-containing water treatment method | |
| JP3429018B2 (en) | Treatment of acidic fluorine-containing water | |
| JP4021688B2 (en) | Method and apparatus for treatment of wastewater containing fluorine and silicon | |
| JPH0839059A (en) | Recovery of semiconductor washing waste water containing organic alkali | |
| JP4487492B2 (en) | Treatment method for fluorine-containing wastewater | |
| JP3257063B2 (en) | Treatment method for fluorine-containing water | |
| JPH0663561A (en) | Fluorine-containing watert treating device | |
| TWI642631B (en) | Fluorine-containing water treatment method and treatment device | |
| JPH078971A (en) | Treatment of ammonium fluoride-containing water | |
| JP4378906B2 (en) | Method and apparatus for treating fluorine-containing water | |
| JP2600569B2 (en) | Treatment method for fluorine-containing water | |
| JP3304400B2 (en) | Treatment method for acidic fluorine-containing water | |
| WO2012014582A1 (en) | Method for treating fluorine-containing water |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20040914 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20041101 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20050208 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20050221 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080311 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090311 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090311 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100311 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110311 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110311 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120311 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120311 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130311 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130311 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140311 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |