JP2007196177A - Method for treating fluorine-containing liquid waste - Google Patents

Method for treating fluorine-containing liquid waste Download PDF

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JP2007196177A
JP2007196177A JP2006019997A JP2006019997A JP2007196177A JP 2007196177 A JP2007196177 A JP 2007196177A JP 2006019997 A JP2006019997 A JP 2006019997A JP 2006019997 A JP2006019997 A JP 2006019997A JP 2007196177 A JP2007196177 A JP 2007196177A
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fluorine
calcium fluoride
based particles
calcium
heavy metal
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JP5005225B2 (en
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Ryuji Nakao
隆二 中尾
Nobuyoshi Yoshimizu
信義 吉水
Nobuyuki Ono
信行 小野
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Nippon Steel Stainless Steel Corp
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Nippon Steel and Sumikin Stainless Steel Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating fluorine-containing liquid waste, in which calcium fluoride and metal hydroxide, which are precipitated at a step of neutralizing fluorine-containing liquid waste containing a fluorine ion and a heavy metal ion, are separated from each other and the former is used satisfactorily in the iron industry as a slag formation promoting agent or an alternative raw material of fluorite being a raw material of hydrofluoric acid and the latter is used satisfactorily in the iron industry as a raw material for stainless steel. <P>SOLUTION: The method for treating fluorine-containing liquid waste comprises the steps of: adding a calcium-containing substance to the fluorine-containing liquid waste containing the fluorine ion and the heavy metal ion to precipitate calcium fluoride-based particles (a particle precipitation step); adding a polymer flocculant to the calcium fluoride-based particle-precipitated liquid to produce flocks of calcium fluoride-based particles; and subjecting the flock-produced liquid to solid-liquid separation to recover calcium fluoride-based particles as a solid portion. A part of the recovered solid portion is returned at the particle precipitation step to further precipitate calcium fluoride on the precipitated calcium fluoride-based particles and increase the particle size thereof and the calcium fluoride-based particles having the increased particle size are recovered as the solid portion by the solid-liquid separation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、ステンレス製造過程や半導体製造過程から排出される弗素イオン及び重金属イオンを含んだ弗素含有廃液から弗素成分、又は弗素成分及び重金属成分を分離する技術に関する。   The present invention relates to a technique for separating a fluorine component or a fluorine component and a heavy metal component from a fluorine-containing waste liquid containing fluorine ions and heavy metal ions discharged from a stainless steel manufacturing process or a semiconductor manufacturing process.

一般に、ステンレス鋼板などの製造工程では、表面光沢、耐食性、加工性などを向上させるため、熱間圧延あるいは冷間圧延後の鋼板に連続焼鈍および酸洗が施される。この酸洗には、硝酸と弗酸を混合した酸洗液が使用されることが多い。酸洗を継続して行なうと、酸洗液中の金属イオン濃度が上昇し、酸洗効力が劣化する。そのため、酸洗効力の劣化した酸洗液の一部を抜き出すとともに、新しい酸洗液を補充して酸洗効力を維持する必要がある。この抜き出した弗素イオン含有廃液中には、金属分（主に、Ｆｅ、Ｃｒ、Ｎｉ）および弗素イオンが多く含まれており、環境保全上、この弗素イオン含有廃液をそのまま処理系外に放出することができない。   In general, in the manufacturing process of a stainless steel plate or the like, continuous annealing and pickling are performed on a hot-rolled or cold-rolled steel plate in order to improve surface gloss, corrosion resistance, workability, and the like. In this pickling, a pickling solution in which nitric acid and hydrofluoric acid are mixed is often used. If pickling is continued, the metal ion concentration in the pickling solution increases and the pickling efficiency deteriorates. Therefore, it is necessary to extract a part of the pickling solution having deteriorated pickling efficiency and to replenish a new pickling solution to maintain the pickling effect. The extracted fluorine ion-containing waste liquid contains a large amount of metal components (mainly Fe, Cr, Ni) and fluorine ions, and this fluorine ion-containing waste liquid is directly discharged out of the treatment system for environmental conservation. I can't.

したがって、この弗素イオン含有廃液は、従来、カルシウム系中和剤で中和し、ｐＨ８〜９に調整し、金属分は水酸化金属として、弗素イオンは弗化カルシウムとして同時に析出させ、それに凝集剤を加え、沈殿槽で沈降分離し、処理水は放流し、沈降した水酸化金属や弗化カルシウムからなる汚泥は脱水機などで脱水し、その脱水汚泥を廃棄物として最終処分していた。   Accordingly, this fluorine ion-containing waste liquid is conventionally neutralized with a calcium-based neutralizing agent and adjusted to pH 8-9, the metal content is simultaneously precipitated as metal hydroxide, and the fluorine ions are simultaneously precipitated as calcium fluoride. And settled in a sedimentation tank, the treated water was discharged, and the sludge composed of precipitated metal hydroxide or calcium fluoride was dehydrated with a dehydrator or the like, and the dehydrated sludge was finally disposed as waste.

また、半導体製造工程においても、エッチングの際、弗化水素酸が使用されるため、弗素イオンを含有した弗素イオン含有廃液が排出される。この弗素イオン含有廃液も、従来、カルシウム系中和剤で中和し、ｐＨ８〜９に調整し、弗素イオンは微細な弗化カルシウムとして析出させ、それにポリ塩化アルミニウム、硫酸バンド、硫酸アルミニウムや塩化鉄などの無機凝集剤および高分子凝集剤を加え、フロックを形成させ沈降しやすくし、沈殿槽で沈降分離し、処理水は放流し、弗化カルシウムと無機凝集材である水酸化アルミニウムや水酸化鉄などを含んだ汚泥は脱水機などで脱水し、その脱水汚泥を廃棄物として最終処分していた。   Also in the semiconductor manufacturing process, since hydrofluoric acid is used during etching, a fluorine ion-containing waste liquid containing fluorine ions is discharged. Conventionally, this fluorine ion-containing waste liquid is also neutralized with a calcium-based neutralizing agent and adjusted to pH 8-9, and fluorine ions are precipitated as fine calcium fluoride, and then polyaluminum chloride, sulfate band, aluminum sulfate and chloride. Adds an inorganic flocculant such as iron and a polymer flocculant to form flocs, facilitates sedimentation, settles and separates in a settling tank, discharges treated water, and discharges calcium fluoride and inorganic flocculants such as aluminum hydroxide and water Sludge containing iron oxide etc. was dehydrated with a dehydrator, and the dehydrated sludge was finally disposed of as waste.

このような状況に対し、弗素イオン含有廃液にＮａＯＨまたはＫＯＨを添加して、弗素イオン含有廃液のｐＨを上昇させて、金属分を水酸化物として沈殿させ、さらに、水酸化物を沈殿除去した上澄液に、そのｐＨが７±１の範囲内になるまでＣａＣｌ2またはＭｇＣｌ2を添加し、弗素イオンを弗化物として沈殿させる方法が、特開平１１−３２２３０４号公報（特許文献１）で開示されている。しかしながら、この技術では、高価な中和剤であるＮａＯＨやＫＯＨや、高価なカルシウム源やマグネシウム源であるＣａＣｌ2またはＭｇＣｌ2を使用するため、金属成分と弗素分を分離することができるものの、非常に処理費が高くなる。
特開平１１−３２２３０４号公報 In response to this situation, NaOH or KOH was added to the fluorine ion-containing waste liquid to raise the pH of the fluorine ion-containing waste liquid, to precipitate the metal component as a hydroxide, and further to remove the hydroxide by precipitation. Japanese Patent Laid-Open No. 11-322304 (Patent Document 1) discloses a method in which CaCl 2 or MgCl 2 is added to the supernatant until the pH falls within a range of 7 ± 1 to precipitate fluorine ions as fluoride. It is disclosed. However, this technology uses expensive neutralizers such as NaOH and KOH, and expensive calcium and magnesium sources such as CaCl 2 or MgCl 2 , so that the metal component and fluorine content can be separated. Processing costs are very high.
JP 11-322304 A

これに対し、本発明はかかる事情に鑑みてなされたもので、弗素イオンと重金属イオンを含有する弗素含有廃液から、弗化カルシウム主体の粒子、又は弗化カルシウム主体の粒子と重金属主体の粒子を安価に分離回収可能で、かつ、回収した粒子の粒子径を大きくして含水率を低下させることが容易である弗素含有廃液の処理方法を提供することを第一の目的とする。また、分離した重金属主体の粒子はステンレス原料等として再使用し、分離した弗化物（弗化カルシウム）は蛍石代替等として再使用できるような、弗素含有廃液の処理方法を提供することを第二の目的とする。   On the other hand, the present invention has been made in view of such circumstances. From a fluorine-containing waste liquid containing fluorine ions and heavy metal ions, calcium fluoride-based particles, or calcium fluoride-based particles and heavy metal-based particles are obtained. It is a first object of the present invention to provide a method for treating a fluorine-containing waste liquid that can be separated and recovered at low cost and that can easily reduce the water content by increasing the particle diameter of the recovered particles. In addition, the present invention provides a method for treating a fluorine-containing waste liquid in which separated heavy metal-based particles can be reused as a raw material for stainless steel, and separated fluoride (calcium fluoride) can be reused as a substitute for fluorite. Second purpose.

本発明者は、上記課題を解決するために、鋭意検討した結果、以下のことを見出した。まず、弗化カルシウム主体の粒子を析出させる弗化カルシウム析出槽内の弗素イオン含有廃液に、廃液中でカルシウムイオンを生じる物質を連続的に投入すると、弗素イオンは弗化カルシウムとなり析出する。その析出した弗化カルシウムからなる超微細な粒子（０．１μｍ以下）は、ブラウン運動領域であり、そのままでは沈殿しないため、凝集剤を添加するなどの手段により沈降しやすくし、沈降分離などの固液分離操作により液体部と分離し、弗化カルシウムからなる粒子を、再度、弗化カルシウム析出槽内に戻した状態にすると、弗化カルシウムからなる粒子は、０．１μｍ以下の超微細な粒子から０．３〜２００μｍ程度の粒子に成長する。粒子径が大きくなることで、かつ、凝集剤の添加などにより、フロックを形成するため、より沈降しやすくなる。また、粒子径を大きくすることで、脱水した際のケーキ水分を低減することができる。   As a result of intensive studies in order to solve the above problems, the present inventors have found the following. First, when a substance that generates calcium ions in a waste liquid is continuously added to a fluorine ion-containing waste liquid in a calcium fluoride precipitation tank in which particles mainly composed of calcium fluoride are precipitated, the fluorine ions are precipitated as calcium fluoride. The ultrafine particles (0.1 μm or less) of the precipitated calcium fluoride are in the Brownian motion region and do not precipitate as they are, so they are easily settled by means such as adding a flocculant, When the particles made of calcium fluoride are separated from the liquid part by solid-liquid separation operation and returned to the calcium fluoride precipitation tank, the particles made of calcium fluoride are ultrafine particles of 0.1 μm or less. Grows into particles of about 0.3 to 200 μm from the particles. Since the flocs are formed by increasing the particle size and adding a flocculant, the particles are more likely to settle. Moreover, the cake water | moisture content at the time of spin-dry | dehydrating can be reduced by enlarging a particle diameter.

次に、弗素イオンと、鉄イオン、クロムイオン、ニッケルイオンなどの重金属イオンを含む弗素イオン含有廃液から、弗素イオンを分離する場合、鉄イオン、クロムイオン、ニッケルイオンはｐＨによってそれらの溶解度が異なり、３価の鉄イオンはｐＨ４以上で、２価の鉄イオンはｐＨ８以上で、３価のクロムイオンはｐＨ６以上で、ニッケルイオンはｐＨ９以上で水酸化物として析出する。
一方、弗素イオンは弗化カルシウムとして析出するため、弗素イオンとカルシウムイオンの溶解度積（ｋｓ）に達しているかどうかで析出するかが決まる。弗素イオンとカルシウムイオンの溶解度積も酸性側になると大きくなる傾向があり、酸性側で弗素イオンを弗化カルシウムとして析出する場合、カルシウムイオンを生じる物質をより多く投入する必要がある。 Next, when separating fluorine ions from fluorine ion-containing waste liquid containing heavy metal ions such as iron ions, chromium ions and nickel ions, the solubility of iron ions, chromium ions and nickel ions varies depending on the pH. Trivalent iron ions are precipitated as hydroxide at pH 4 or higher, divalent iron ions are pH 8 or higher, trivalent chromium ions are pH 6 or higher, and nickel ions are pH 9 or higher.
On the other hand, since fluorine ions are precipitated as calcium fluoride, whether they are precipitated is determined by whether the solubility product (ks) of fluorine ions and calcium ions has been reached. The solubility product of fluorine ions and calcium ions also tends to increase as they become acidic, and when fluorine ions are precipitated as calcium fluoride on the acidic side, it is necessary to add more substances that generate calcium ions.

後述する理由により、カルシウムイオンを生じる物質（カルシウムを含む物質と呼称する）としては、酸化カルシウム、水酸化カルシウム、炭酸カルシウムのうちの１種または2種以上が適当であるが、これらは、中和作用があり、弗化カルシウム析出槽内のｐＨを上昇させる。すなわち、結果的に弗化カルシウムの溶解度がｐＨ上昇に伴って変化すると考えることができる。３価の鉄イオン、２価の鉄イオン、３価のクロムイオン、ニッケルイオンのうち、もっとも低ｐＨで析出するのが、３価の鉄イオンであり、３価の鉄イオンと弗素イオンの分離が重要なポイントとなる。   For reasons described later, one or more of calcium oxide, calcium hydroxide, and calcium carbonate are suitable as a substance that generates calcium ions (referred to as a substance containing calcium). It has a summing action and raises the pH in the calcium fluoride precipitation tank. That is, as a result, it can be considered that the solubility of calcium fluoride changes as the pH increases. Of the trivalent iron ions, divalent iron ions, trivalent chromium ions, and nickel ions, the one that precipitates at the lowest pH is the trivalent iron ion, which separates the trivalent iron ion and the fluorine ion. Is an important point.

ステンレス製造工程から排出される、弗素イオン、３価の鉄イオン、３価のクロムイオン、２価のニッケルイオンを含有する酸性の排水では、カルシウムを含む物質を投入すると、ｐＨ３．７以下の領域で、好ましくはｐＨ３．０以下の領域で、弗化カルシウムと水酸化金属との間の溶解度差により、弗化カルシウムが主体に析出し、３価のクロムイオンおよび２価のニッケルイオンは析出が少なく、３価の鉄イオンの析出をある程度抑制することができ、弗化カルシウム分５０質量％以上の成分を有する析出物となることを見出した。   In acidic wastewater containing fluorine ions, trivalent iron ions, trivalent chromium ions, and divalent nickel ions discharged from the stainless steel manufacturing process, when a substance containing calcium is added, the pH is below 3.7 Preferably, in the region of pH 3.0 or less, calcium fluoride is mainly precipitated due to the difference in solubility between calcium fluoride and metal hydroxide, and trivalent chromium ions and divalent nickel ions are precipitated. It has been found that the precipitation of trivalent iron ions can be suppressed to some extent, and a precipitate having a component having a calcium fluoride content of 50% by mass or more is obtained.

また、回収した弗化カルシウム主体の粒子からなる固体部の一部を前記弗化カルシウム主体の粒子を析出させる工程に投入することで、固体部中の弗化カルシウム主体の粒子に、更に弗化カルシウムを析出させて粒子径を増大化し、濾過性や脱水性が向上し、かつ、弗素イオンと重金属イオンとに効率的に分離できることを見出した。そのためには、定常状態となった弗化カルシウム析出槽内の固形物量をＡ（ｋｇ）とし、弗素イオンと重金属イオンを含有する弗素含有廃液に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子が新たに析出する量をＢ（ｋｇ／日）としたとき、つまり、
Ａ（ｋｇ）＝弗化カルシウム析出槽容量（ｍ3 ）×弗化カルシウム析出槽内ＳＳ濃度（ｋｇ／ｍ3）
Ｂ（ｋｇ／日）＝弗素含有廃液処理水量（ｍ3 ／日）×（弗素含有廃液中の弗素イオン濃度（ｋｇ／ｍ3 ）―弗化カルシウム析出後の液体部の弗素イオン濃度（ｋｇ／ｍ3 ）÷弗化カルシウム析出槽内析出物中弗素含有量（質量％）、
ここで、弗素イオン濃度は、弗素イオン電極による分析（イオン電極法）が好ましい。 In addition, a part of the solid portion composed of the recovered calcium fluoride-based particles is put into the step of precipitating the calcium fluoride-based particles, whereby the calcium fluoride-based particles in the solid portion are further fluorinated. It has been found that calcium is deposited to increase the particle size, filterability and dehydration are improved, and fluorine ions and heavy metal ions can be efficiently separated. For that purpose, the amount of solids in the calcium fluoride precipitation tank in a steady state is set to A (kg), a substance containing calcium is added to a fluorine-containing waste liquid containing fluorine ions and heavy metal ions, and calcium fluoride is added. When the amount of the main particles newly precipitated is B (kg / day), that is,
A (kg) = calcium fluoride precipitation tank capacity (m 3 ) × SS concentration in calcium fluoride precipitation tank (kg / m 3 )
B (kg / day) = Amount of treated water containing fluorine (m 3 / day) × (fluorine ion concentration in fluorine containing waste liquid (kg / m 3 ) −fluorine ion concentration in the liquid part after precipitation of calcium fluoride (kg / m 3 ) ÷ fluorine content (mass%) in the precipitate in the calcium fluoride precipitation tank,
Here, the fluorine ion concentration is preferably analyzed by a fluorine ion electrode (ion electrode method).

Ａ÷Ｂを０．０５（日）以上、１．０（日）以下となるように、反応槽内の大きさおよび回収した弗化カルシウム主体の粒子からなる固体部の一部を前記弗化カルシウム主体の粒子を析出させる工程へ投入する量を調整することが重要で、０．０５（日）未満であれば、新たに析出する弗化カルシウム分が既に発生している弗化カルシウム主体の粒子表面へ析出せずに、超微細な（０．１μｍ以下）新たな粒子を形成し、その結果、粒子径が増大せずに、濾過性や脱水性を十分に高めることができないばかりか、超微細な粒子が多量に存在するため、高分子凝集材を多量に使用しなければならない。一方、１．０（日）より大きくしても、さらなる濾過性や脱水性の向上あまり見込めず、反応槽容量が過大となり攪拌動力を多く必要となり、もしくは、回収した弗化カルシウム主体の粒子の一部を析出させる工程へ投入する量が過大となりポンプ動力を多く必要となり、経済的でない。   A part of the solid portion made of the recovered calcium fluoride-based particles is fluorinated so that A ÷ B is 0.05 (day) or more and 1.0 (day) or less. It is important to adjust the amount of calcium-based particles to be deposited in the step of precipitation, and if it is less than 0.05 (day), the newly precipitated calcium fluoride content is already generated. Not only does it precipitate on the surface of the particles, but it forms new ultrafine (0.1 μm or less) new particles. As a result, the particle diameter does not increase and the filterability and dewaterability cannot be sufficiently enhanced. Since there are a large amount of ultrafine particles, a large amount of polymer aggregate must be used. On the other hand, even if it is larger than 1.0 (day), further improvement in filterability and dehydrability cannot be expected so much, the reaction tank capacity becomes excessive and a large amount of stirring power is required, or the recovered particles of calcium fluoride-based particles The amount to be introduced into the process of depositing a part becomes excessive, and a lot of pump power is required, which is not economical.

また、ステンレス酸洗廃液や半導体廃液のように、弗素イオン濃度が異なる２種類以上の弗素含有廃液が存在し、かつ、それぞれが濃度変動を伴う場合、従来よりよく行われる一定量混合では、濃度変動が大きく、前記の弗化カルシウム主体の粒子の増大化が適切に行われず、超微細な粒子が多量に発生する。その結果、濾過性や脱水性を十分に高めることができないばかりか、超微細な粒子が多量に存在するため、高分子凝集材を多量に使用しなければならない。そこで、弗素イオン濃度を一定にするように制御することが重要である。この際、弗素イオン濃度の制御値は高い方が、前記の弗素イオンと重金属イオンとの分離性が向上する。弗素イオン濃度が低いと、弗化カルシウム析出後の液体部の弗素イオン濃度をより低く抑えることが必要となり、溶解度積の関係から、より多くのカルシウムイオンを投入する必要があり、経済的でなくなるためである。   In addition, when there are two or more types of fluorine-containing waste liquids with different fluorine ion concentrations, such as stainless steel pickling waste liquid and semiconductor waste liquid, and each is accompanied by concentration fluctuation, Fluctuation is large, and the increase of the above-mentioned calcium fluoride-based particles is not appropriately performed, and a large amount of ultrafine particles are generated. As a result, not only can filterability and dewaterability be sufficiently improved, but a large amount of ultrafine particles exist, so that a large amount of polymer agglomerate must be used. Therefore, it is important to control the fluorine ion concentration to be constant. At this time, the higher the control value of the fluorine ion concentration, the better the separation between the fluorine ions and the heavy metal ions. If the fluorine ion concentration is low, it is necessary to keep the fluorine ion concentration in the liquid part after calcium fluoride precipitation lower, and it is necessary to input more calcium ions due to the solubility product, which is not economical. Because.

すなわち、本発明は、上記知見に基づいてなされたものであり、その要旨は以下のとおりである。
（１）弗素イオンと重金属イオンを含有する弗素含有廃液に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子を析出させる工程と、前記工程の処理液に高分子凝集剤を添加して、弗化カルシウム主体の粒子の凝集体を生成する工程と、前記凝集体を生成する工程の処理液を固液分離して、弗化カルシウム主体の粒子を固体部として回収する工程とを有し、前記回収した固体部の一部を前記弗化カルシウム主体の粒子を析出させる工程に投入し、固体部中の弗化カルシウム主体の粒子に、更に弗化カルシウムを析出させて粒子径を増大化し、当該増大化した弗化カルシウム主体の粒子を前記固液分離により固体部として回収することを特徴とする弗素含有廃液の処理方法。 That is, the present invention has been made based on the above findings, and the gist thereof is as follows.
(1) adding a substance containing calcium to a fluorine-containing waste liquid containing fluorine ions and heavy metal ions to precipitate calcium fluoride-based particles, and adding a polymer flocculant to the treatment liquid of the above process And a step of producing an aggregate of calcium fluoride-based particles and a step of recovering the calcium fluoride-based particles as a solid part by solid-liquid separation of the treatment liquid in the step of producing the aggregates. Then, a part of the collected solid part is put into the step of precipitating the calcium fluoride-based particles, and further calcium fluoride is precipitated on the calcium fluoride-based particles in the solid part to increase the particle diameter. And treating the increased calcium fluoride-based particles as a solid part by the solid-liquid separation.

（２）前記回収した弗化カルシウム主体の粒子からなる固体部の一部を前記弗化カルシウム主体の粒子を析出させる工程に投入する際に、弗化カルシウム主体の粒子を析出させる工程内の固形物量をＡ（ｋｇ）とし、弗素イオンと重金属イオンを含有する弗素含有廃液に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子が新たに析出する量をＢ（ｋｇ／日）としたとき、
Ａ÷Ｂを０．０５（日）以上、１．０（日）以下にすることを特徴とする前記（１）記載の弗素含有廃液の処理方法。 (2) When a part of the recovered solid portion composed of calcium fluoride-based particles is added to the step of precipitating calcium fluoride-based particles, the solids in the step of precipitating calcium fluoride-based particles Let A (kg) be the amount of substance, add a substance containing calcium to the fluorine-containing waste liquid containing fluorine ions and heavy metal ions, and let B (kg / day) be the amount of newly precipitated calcium fluoride-based particles. When
The method for treating a fluorine-containing waste liquid according to the above (1), wherein A ÷ B is set to 0.05 (day) or more and 1.0 (day) or less.

（３）前記固液分離によって固体部と分離される重金属イオンを含む液体部を、ｐＨ６超１０以下に調整して重金属主体の粒子を析出させる工程と、当該重金属主体の粒子を析出させる工程の処理液に高分子凝集剤を添加して、重金属主体の粒子の凝集体を生成する工程と、当該重金属主体の凝集体を生成する工程の処理液を固液分離によって重金属主体の粒子を固体部として回収する工程とを更に有することを特徴とする前記（１）または（２）に記載の弗素含有廃液の処理方法。 (3) a step of adjusting the liquid part containing heavy metal ions separated from the solid part by solid-liquid separation to a pH of more than 6 to 10 and precipitating heavy metal-based particles, and a step of precipitating the heavy metal-based particles A polymer flocculant is added to the treatment liquid to produce an aggregate of heavy metal-based particles, and the treatment liquid of the step of producing the heavy metal-based aggregate is separated into solid parts by solid-liquid separation. The method for treating a fluorine-containing waste liquid according to (1) or (2), further comprising:

（４）前記金属イオンにＣｒ3+、Ｎｉ2+の少なくともいずれかを含む場合、前記弗化カルシウム主体の粒子を析出させる際のｐＨ調整をｐＨ３．８以上６以下とすることを特徴とする前記（１）または（２）に記載の弗素含有廃液の処理方法。
（５）前記金属イオンにＦｅ3+を含む場合、前記弗化カルシウム主体の粒子を析出させる際のｐＨ調整をｐＨ２．０以上３．７以下とすることを特徴とする前記（１）または（２）に記載の弗素含有廃液の処理方法。 (4) When the metal ion contains at least one of Cr 3+ and Ni 2+ , pH adjustment when precipitating the particles mainly composed of calcium fluoride is pH 3.8 or more and 6 or less. The method for treating a fluorine-containing waste liquid according to the above (1) or (2).
(5) In the case where Fe 3+ is contained in the metal ion, the pH adjustment when the calcium fluoride-based particles are precipitated is adjusted to pH 2.0 or more and 3.7 or less, (1) or ( The method for treating a fluorine-containing waste liquid as described in 2).

（６）前記回収した重金属主体の固体部の一部を前記重金属主体の粒子を析出させる工程に投入し、固体部中の重金属主体の粒子に、更に重金属イオンを接触させて粒子径を増大化し、当該増大化した重金属主体の粒子を固液分離により回収することを特徴とする前記（１）〜（５）のいずれか１つに記載の弗素含有廃液の処理方法。
（７）弗素イオンと重金属イオンを含有する弗素濃度の異なる２種類以上の弗素含有廃液を混合して処理する場合、弗素イオン電極を用いて、混合後の弗素含有廃液中に含まれる弗素イオン濃度の変動幅を±５０％以内に制御することを特徴とする前記（１）〜（６）のいずれか１つに記載の弗素含有廃液の処理方法。 (6) A part of the recovered heavy metal-based solid part is put into the step of precipitating the heavy metal-based particles, and the heavy metal ions are further brought into contact with the heavy metal-based particles in the solid part to increase the particle diameter. The method for treating a fluorine-containing waste liquid according to any one of (1) to (5), wherein the increased heavy metal-based particles are recovered by solid-liquid separation.
(7) When two or more kinds of fluorine-containing waste liquids containing fluorine ions and heavy metal ions having different concentrations are mixed and treated, the fluorine ion concentration in the fluorine-containing waste liquid after mixing is obtained using a fluorine ion electrode. The method of treating a fluorine-containing waste liquid according to any one of the above (1) to (6), wherein the fluctuation range is controlled within ± 50%.

（８）弗化カルシウム主体の粒子の凝集体を生成する工程での処理液を、固液分離した後の液体部の弗素イオン濃度を連続又は間欠に測定し、当該測定濃度に応じて弗化カルシウム主体の粒子を析出させる工程へ投入するカルシウムを含む物質の投入量を制御することで、その弗素イオン濃度の変動幅を±５０％以内に制御することを特徴とする前記（１）〜（７）のいずれか１つに記載の弗素含有廃液の処理方法。
（９）前記固液分離して固体部として回収した弗化カルシウム主体の粒子を、金属精錬過程のスラグの滓化促進剤、又は弗化水素酸の原料である蛍石の代替物として使用することを特徴とする前記（１）〜（８）のいずれか１つに記載の弗素含有廃液の処理方法。 (8) Measure the fluoride ion concentration in the liquid part after solid-liquid separation of the treatment liquid in the step of forming the aggregate of calcium fluoride-based particles, and fluorinate according to the measured concentration (1) to (1) above, wherein the fluctuation range of the fluorine ion concentration is controlled within ± 50% by controlling the amount of calcium-containing substance to be introduced into the step of precipitating calcium-based particles. The method for treating a fluorine-containing waste liquid according to any one of 7).
(9) The calcium fluoride-based particles recovered as a solid part after the solid-liquid separation are used as a slag hatching accelerator in the metal refining process or as a substitute for fluorite, which is a raw material of hydrofluoric acid. The method for treating a fluorine-containing waste liquid according to any one of (1) to (8), wherein:

（１０）前記固液分離して固体部として回収した重金属主体の粒子を、ステンレス原料、又は合金鉄原料として使用することを特徴とする前記（３）〜（９）のいずれか１つに記載の弗素含有廃液の処理方法。
（１１）前記添加するカルシウムを含む物質が、酸化カルシウム、水酸化カルシウム、炭酸カルシウムのうちの１種又は２種以上であることを特徴とする前記（１）〜（１０）のいずれか１つに記載の弗素含有廃液の処理方法にある。 (10) The heavy metal-based particles recovered as a solid part after the solid-liquid separation are used as a stainless steel raw material or an alloy iron raw material, as described in any one of (3) to (9) above Method for treating fluorine-containing waste liquid.
(11) Any one of (1) to (10), wherein the substance containing calcium to be added is one or more of calcium oxide, calcium hydroxide, and calcium carbonate. The method for treating a fluorine-containing waste liquid described in 1.

以上述べたように、本発明により、弗素イオンと重金属イオンを含有する弗素含有廃液から、弗化カルシウム、又は弗化カルシウムと鉄・クロム・ニッケルなどからなる水酸化金属とに分離し、安価に回収することができる。また、製鉄業における滓化促進剤や弗化水素酸の蛍石代替原料と、ステンレス原料として有効利用することができる。   As described above, according to the present invention, a fluorine-containing waste liquid containing fluorine ions and heavy metal ions is separated into calcium fluoride or a metal hydroxide composed of calcium fluoride and iron, chromium, nickel, etc. It can be recovered. Moreover, it can be effectively used as a hatching accelerator in the steel industry, a fluorite substitute raw material for hydrofluoric acid, and a stainless steel raw material.

以下、本発明を更に詳細に説明する。
本発明に係わる弗素イオン含有廃液の処理方法は、弗素イオンと重金属イオンを含む弗素含有廃液をその処理対象とする。弗化カルシウム析出槽に、弗素イオンと重金属イオンを含む弗素含有廃液を投入した後、又は、投入すると共に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子を析出させた（粒子径０．１μｍ以下）後、高分子凝集材を加え、沈殿法などの固液分離により弗化カルシウム主体の粒子を回収することができる。 Hereinafter, the present invention will be described in more detail.
The method for treating a fluorine ion-containing waste liquid according to the present invention targets a fluorine-containing waste liquid containing fluorine ions and heavy metal ions. Fluorine-containing waste liquid containing fluorine ions and heavy metal ions was added to the calcium fluoride precipitation tank, or at the same time, a substance containing calcium was added to precipitate calcium fluoride-based particles (particle size After 0.1 μm or less, the polymer agglomerate is added, and the calcium fluoride-based particles can be recovered by solid-liquid separation such as precipitation.

しかしながら、そのようにして作成した粒子径は小さく、脱水性が悪い。そこで、さらに、析出した弗化カルシウム主体の粒子に、弗素イオンとカルシウムイオンを接触させることで、粒子径を増大化することができ、直径０．１μｍ以下の粒子を０．３〜２００μｍの緻密な粒子にすることができ、高分子凝集材を加え、沈殿法などの固液分離により脱水性が改善された弗化カルシウム主体の粒子を回収することができる。
カルシウムを含む物質としては、炭酸カルシウム、酸化カルシウム、水酸化カルシウム、塩化カルシウム、石膏、硝酸カルシウムなどがある。塩化カルシウム、石膏、硝酸カルシウムは価格が相対的に高く、石膏は反応性が悪く、実用性に乏しい。よって、酸化カルシウム、水酸化カルシウム、炭酸カルシウムがカルシウム源として実用的である。 However, the particle size thus prepared is small and the dehydration property is poor. Therefore, the particle diameter can be increased by bringing fluorine ions and calcium ions into contact with the precipitated calcium fluoride-based particles, and particles having a diameter of 0.1 μm or less can be made dense with a density of 0.3 to 200 μm. It is possible to collect the particles mainly composed of calcium fluoride having improved dehydrating property by solid-liquid separation such as precipitation method by adding a polymer aggregate.
Examples of the substance containing calcium include calcium carbonate, calcium oxide, calcium hydroxide, calcium chloride, gypsum, and calcium nitrate. Calcium chloride, gypsum, and calcium nitrate are relatively expensive, and gypsum has poor reactivity and is not practical. Therefore, calcium oxide, calcium hydroxide, and calcium carbonate are practical as calcium sources.

更に、酸化カルシウムおよび水酸化カルシウムはスラリー化するとｐＨ１２程度の高アルカリであり、炭酸カルシウムはｐＨ９程度の弱アルカリであるため、ｐＨを調整するアルカリ剤としても使用できる。これらのアルカリ剤を弗素含有廃液に投入すると、アルカリ剤の粒子近傍は高アルカリ状態となり、その粒子近傍領域では重金属イオンが水酸化金属として析出する。一度、析出した水酸化金属は、再溶解するのに時間がかかる。よって、重金属イオンと弗素イオンを分離する際には、ｐＨ制御が重要であるため、炭酸カルシウムがより好ましい。   Further, when calcium oxide and calcium hydroxide are slurried, they are highly alkaline with a pH of about 12, and calcium carbonate is a weak alkali with a pH of about 9, so that it can be used as an alkaline agent for adjusting the pH. When these alkali agents are added to the fluorine-containing waste liquid, the vicinity of the alkali agent particles becomes highly alkaline, and heavy metal ions are precipitated as metal hydroxide in the vicinity of the particles. Once precipitated, the metal hydroxide takes time to redissolve. Therefore, when separating heavy metal ions and fluorine ions, since pH control is important, calcium carbonate is more preferable.

次に、弗化水素酸を含む酸洗液でステンレス鋼板を酸洗する際に発生する、弗素イオンに加え、鉄イオン、クロムイオン、ニッケルイオンを含有した弗素イオン含有廃液を処理する場合、ｐＨ操作によって弗化カルシウム主体の析出物と重金属を主体に含む析出物とに分離することができる。弗化カルシウムの析出は、弗素イオンとカルシウムイオンの溶解度積（ｋｓ）で決まるが、ｐＨに対する溶解度積は、図１に示すように、酸性側になると大きくなる。つまり、酸性側で弗素イオンが弗化カルシウムとして析出する場合、カルシウムイオンをより多く投入する必要がある。   Next, in the case of treating a fluorine ion-containing waste liquid containing iron ions, chromium ions, nickel ions in addition to fluorine ions, which is generated when pickling a stainless steel plate with a pickling solution containing hydrofluoric acid, pH By the operation, it can be separated into a precipitate mainly composed of calcium fluoride and a precipitate mainly composed of heavy metals. The precipitation of calcium fluoride is determined by the solubility product (ks) of fluorine ions and calcium ions, but the solubility product with respect to pH increases as it becomes acidic as shown in FIG. That is, when fluorine ions are precipitated as calcium fluoride on the acidic side, it is necessary to add more calcium ions.

前述のようにアルカリ剤でもある酸化カルシウム、水酸化カルシウム、炭酸カルシウムのうちの１種又は２種以上をカルシウム源として使用し、重金属イオンと弗素イオンを分離する場合、弗素イオン析出に必要なカルシウム源を投入すると、ｐＨが３．７以上となり、重金属イオンとして３価の鉄イオン（Ｆｅ3+）を含む場合に、３価の鉄イオンと分離できなくなることがある。このような場合、カルシウム源として、塩化カルシウム、石膏、硝酸カルシウムのような投入してもｐＨの上昇がほとんど起こらない塩を使用することができる。あるいは、弗化水素酸を含有する酸洗液、もしくは、弗化カルシウム析出槽に、塩酸、硝酸などの酸もしくはそれらを含む廃酸を投入し、弗化カルシウム析出槽内のｐＨを２．０〜３．７、好ましくはｐＨを２．０〜３．０にすることで、３価の鉄イオンとの分離を促進することができる。 As described above, when one or more of calcium oxide, calcium hydroxide, and calcium carbonate, which is also an alkali agent, is used as a calcium source and heavy metal ions and fluorine ions are separated, calcium necessary for precipitation of fluorine ions When the source is added, the pH becomes 3.7 or more, and when heavy metal ions contain trivalent iron ions (Fe 3+ ), they may not be separated from trivalent iron ions. In such a case, a salt that hardly raises the pH even when added, such as calcium chloride, gypsum, and calcium nitrate, can be used as the calcium source. Alternatively, a pickling solution containing hydrofluoric acid or an acid such as hydrochloric acid or nitric acid or a waste acid containing them is put into a calcium fluoride precipitation tank, and the pH in the calcium fluoride precipitation tank is set to 2.0. Separation from trivalent iron ions can be promoted by setting the pH to 2.0 to 3.0, preferably 2.0 to 3.0.

重金属イオンとしてクロムイオン（Ｃｒ3+）とニッケルイオン（Ｎｉ2+）を含む場合、例えば、弗素イオンと３価の鉄イオンを分離せず、クロムイオンとニッケルイオンを弗素イオンから分離するケースでは、弗化カルシウム析出槽のｐＨは３．８〜６にすればよく、前記のような塩、酸もしくは廃酸を投入する必要性は少なくなる。重金属イオン混入量が少なく重金属イオンと分離する必要がない場合（例：半導体製造過程から排出される弗素イオンを含んだ酸排水）では、弗化カルシウム析出槽のｐＨを６超１０以下、好ましくは７〜９に制御することで、排水中より弗素イオンを弗化カルシウムとして析出することができる。 When chromium ions (Cr 3+ ) and nickel ions (Ni 2+ ) are included as heavy metal ions, for example, in the case of separating chromium ions and nickel ions from fluorine ions without separating fluorine ions and trivalent iron ions. The pH of the calcium fluoride precipitation tank may be 3.8 to 6, and the necessity of introducing the salt, acid or waste acid as described above is reduced. When the amount of heavy metal ions is small and it is not necessary to separate heavy metal ions (eg, acid wastewater containing fluorine ions discharged from the semiconductor manufacturing process), the pH of the calcium fluoride precipitation tank is more than 6 and less than 10, preferably By controlling to 7 to 9, fluorine ions can be precipitated as calcium fluoride from the waste water.

弗素含有廃液として、弗素濃度が異なる２種類以上の弗素含有廃液があり、かつ、その弗素イオン濃度が著しく変化する場合（通常、これに伴って、重金属イオン濃度も変化する）、弗化カルシウム析出槽中での析出量が不安定になり、かつ、微細粒子が多く発生し、高分子凝集材の量が不足し、フロック化が不十分となり、安定的な固液分離操作が難しくなる。また、弗素イオン濃度の変化が激しいと、弗素含有廃液中の重金属イオン濃度も伴って変化するが、水酸化金属の溶解度はあるｐＨに対して一定であるので、各重金属イオンの大部分が析出するｐＨが変化し、弗化カルシウム析出槽で弗化カルシウム主体の粒子を析出するための最適なｐＨは常に変化してしまい、安定的な分離率を得ることはできない。これに対し、弗素イオン濃度を連続的に測定しながら、弗素イオン濃度を一定に調整するよう弗素イオン濃度の異なる２種類以上の弗素含有廃液を混合することにより、弗素イオンと重金属イオンとの分離率を安定的に維持することができる。   As fluorine-containing waste liquid, there are two or more types of fluorine-containing waste liquids with different fluorine concentrations, and when the fluorine ion concentration changes significantly (usually, the heavy metal ion concentration also changes), calcium fluoride precipitation The amount of precipitation in the tank becomes unstable, a large amount of fine particles are generated, the amount of the polymer agglomerate is insufficient, the flocculation becomes insufficient, and stable solid-liquid separation operation becomes difficult. In addition, if the concentration of fluorine ions changes drastically, the concentration of heavy metal ions in the fluorine-containing waste liquid also changes. However, since the solubility of metal hydroxide is constant at a certain pH, most of each heavy metal ion is precipitated. The optimum pH for precipitating calcium fluoride-based particles in the calcium fluoride precipitation tank always changes, and a stable separation rate cannot be obtained. On the other hand, separation of fluorine ions and heavy metal ions is performed by mixing two or more types of fluorine-containing waste liquids having different fluorine ion concentrations so as to adjust the fluorine ion concentration to a constant while continuously measuring the fluorine ion concentration. The rate can be maintained stably.

前記の析出した弗化カルシウム主体の粒子は高分子凝集剤投入後、沈澱槽、遠心分離機そして濾過装置などで分離することができる。分離した一部の弗化カルシウム主体の粒子を再度弗化カルシウム析出槽に投入することにより、弗化カルシウム主体の粒子に、さらに、弗素イオンとカルシウムイオンを接触させて粒子径を増大化することができ、直径０．１μｍ以下の粒子を０．３〜２００μｍの緻密な粒子にすることができる（粒子径測定方法：レーザー回折・散乱法）。   The precipitated calcium fluoride-based particles can be separated with a precipitation tank, a centrifuge, a filtration device, etc. after charging the polymer flocculant. By introducing a part of the separated calcium fluoride-based particles into the calcium fluoride precipitation tank again, the particle size can be increased by bringing fluorine ions and calcium ions into contact with the calcium fluoride-based particles. The particles having a diameter of 0.1 μm or less can be made into fine particles having a diameter of 0.3 to 200 μm (particle diameter measuring method: laser diffraction / scattering method).

この場合、弗化カルシウム主体の粒子を析出させる反応槽内の固形物量をＡ（ｋｇ）とし、弗素イオンと重金属イオンを含有する弗素含有廃液に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子が新たに析出する量をＢ（ｋｇ／日）としたとき、
Ａ÷Ｂを０．０５（日）以上、１．０（日）以下にするのがよい。
具体的には、沈殿槽で分離、もしくは、濾過装置で分離した弗化カルシウム主体の粒子からなるスラリー濃度を適宜測定しながら、弗化カルシウム析出槽内に投入するスラリー量を決定したり、あるいは、弗化カルシウム析出槽内のスラリー濃度を連続測定することで、弗化カルシウム析出槽内のスラリー濃度を一定にする。このようにして粒子径を増大化した粒子を含むスラリーは、一部、引抜かれ、脱水機により脱水されケーキ（弗化カルシウム系脱水ケーキともいう）となる。 In this case, the amount of solid matter in the reaction vessel in which the particles mainly composed of calcium fluoride are precipitated is A (kg), and a calcium-containing substance is added to a fluorine-containing waste liquid containing fluorine ions and heavy metal ions. When the amount of newly precipitated main particles is B (kg / day),
A ÷ B is preferably 0.05 (day) or more and 1.0 (day) or less.
Specifically, the amount of slurry to be introduced into the calcium fluoride precipitation tank is determined while appropriately measuring the slurry concentration consisting of calcium fluoride-based particles separated by a precipitation tank or separated by a filtration device, or The slurry concentration in the calcium fluoride precipitation tank is made constant by continuously measuring the slurry concentration in the calcium fluoride precipitation tank. The slurry containing particles whose particle diameter has been increased in this way is partially drawn out and dehydrated by a dehydrator to form a cake (also referred to as a calcium fluoride-based dehydrated cake).

弗素イオンを分離した後の３価の鉄イオン、クロムイオン、ニッケルイオンなどの重金属イオンを含む廃液は、アルカリ剤を投入して、ｐＨ６以上１０以下にすることで、水酸化物として析出する。これらの水酸化物からなる粒子は、高分子凝集剤投入後、沈澱槽で分離したり、または、濾過装置により分離することができる。分離された重金属主体の粒子を含むスラリーは、引抜かれ、脱水機により脱水されケーキ（重金属系脱水ケーキ）となる。   Waste liquids containing heavy metal ions such as trivalent iron ions, chromium ions, nickel ions, etc. after separating fluorine ions are precipitated as hydroxides by introducing an alkali agent to pH 6 or more and 10 or less. The particles composed of these hydroxides can be separated in a precipitation tank after the polymer flocculant has been added, or separated by a filtration device. The separated slurry containing heavy metal-based particles is drawn out and dehydrated by a dehydrator to form a cake (heavy metal dehydrated cake).

また、重金属系脱水ケーキを、ステンレスあるいは合金鉄原料として利用する場合、他原料との混合比に大きく左右されるが、弗素含有量をおおよそ２０質量％（ドライ換算）以下、好ましくは１０質量％（ドライ換算）以下にする必要がある。弗素含有量が２０質量％超（弗化カルシウム換算で４１．１％超）のような弗化カルシウムを多量に含んだ脱水ケーキをステンレス原料もしくは合金鉄原料として使用した場合、下記（１）式の反応により弗化水素（ＨＦ）が生成し、ステンレス原料中の弗素含有量が高いと（１）式はより顕著となる。この弗化水素は該精錬炉の排ガス系や排ガス処理水系等の設備を腐食させてしまう。
ＣａＦ2＋Ｈ2Ｏ→ＣａＯ＋２ＨＦ ・・・（１） Further, when the heavy metal dehydrated cake is used as a raw material for stainless steel or alloy iron, the fluorine content is approximately 20% by mass (dry conversion) or less, preferably 10% by mass, although it depends greatly on the mixing ratio with other raw materials. (Dry conversion) Must be below. When a dehydrated cake containing a large amount of calcium fluoride with a fluorine content of more than 20% by mass (more than 41.1% in terms of calcium fluoride) is used as a stainless steel material or an alloyed iron material, the following formula (1) The hydrogen fluoride (HF) is generated by the reaction of (1), and the formula (1) becomes more remarkable when the fluorine content in the stainless steel raw material is high. This hydrogen fluoride corrodes equipment such as the exhaust gas system and exhaust gas treatment water system of the smelting furnace.
CaF 2 + H 2 O → CaO + 2HF (1)

よって、重金属析出槽内で析出する金属鉄主体の粒子中の弗素含有量をおおよそ２０質量％（ドライ換算）以下にするためには、弗化カルシウム析出槽から排出される処理水中の弗素イオン濃度を測定し、弗素イオン濃度を制御する必要がある。
具体的には、弗素イオン濃度を手分析、好ましくはイオン電極を用いた連続分析（イオン電極法）で把握し、その弗素イオン濃度値が制御値より高い場合には、弗化カルシウム析出槽中にカルシウムを含む物質を入れ、弗化カルシウムを析出させ、弗化カルシウム析出槽からの処理水中の弗素イオン濃度を制御値まで下げるようにする。 Therefore, in order to reduce the fluorine content in the particles mainly composed of metallic iron deposited in the heavy metal precipitation tank to about 20% by mass (dry conversion) or less, the concentration of fluorine ions in the treated water discharged from the calcium fluoride precipitation tank It is necessary to measure the fluorine ion concentration.
Specifically, the fluorine ion concentration is grasped by manual analysis, preferably continuous analysis using an ion electrode (ion electrode method), and if the fluorine ion concentration value is higher than the control value, A substance containing calcium is put into the container to precipitate calcium fluoride so that the fluorine ion concentration in the treated water from the calcium fluoride precipitation tank is lowered to a control value.

制御値としては、重金属析出槽内で析出する金属鉄主体の粒子中の弗素含有量をおおよそ２０質量％（ドライ換算）以下にするように、金属鉄主体の粒子中の成分を随時測定しながら決定する。また、ステンレス鋼板を酸洗した場合に発生する弗素含有廃液としては、通常、鋼板の酸洗した後の濃厚な酸廃液と、鋼板の表面に残存した酸を水で洗い流す際に発生するリンズ廃液がある。リンズ廃液中の弗素イオン濃度は１００〜３０００ｍｇ／Ｌと低濃度であるが、濃厚な酸廃液中の弗素イオン濃度は８０〜３００ｇ／Ｌ程度と高濃度であり、濃度差が非常に大きく、かつ、それぞれ大きく変動する。   As a control value, while measuring the components in the metal iron-based particles as occasion demands so that the fluorine content in the metal iron-based particles deposited in the heavy metal precipitation tank is approximately 20% by mass (dry conversion) or less. decide. In addition, the fluorine-containing waste liquid that is generated when pickling stainless steel sheets is usually concentrated acid waste liquid after pickling the steel sheet and rinse waste liquid that is generated when the acid remaining on the surface of the steel sheet is washed away with water. There is. The fluorine ion concentration in the Linds waste liquid is as low as 100 to 3000 mg / L, but the fluorine ion concentration in the concentrated acid waste liquid is as high as about 80 to 300 g / L, and the difference in concentration is very large. , Each varies greatly.

このような濃度変化が激しい弗素含有廃液を混合して処理すると、弗化カルシウム析出槽中での析出量が不安定になり、安定的な固液分離操作が難しくなる。また、弗素イオン濃度の変化が激しいと、弗素含有廃液中の金属イオン濃度も伴って変化するが、水酸化金属の溶解度はあるｐＨに対して一定であるので、金属イオンが析出するｐＨが変化し、弗化カルシウム析出槽で弗化カルシウム主体の粒子を析出するための最適なｐＨは常に変化してしまい、安定的な分離率を得ることはできない。   When such a fluorine-containing waste liquid having a drastic change in concentration is mixed and processed, the amount of precipitation in the calcium fluoride precipitation tank becomes unstable, and stable solid-liquid separation operation becomes difficult. In addition, if the fluorine ion concentration changes drastically, the metal ion concentration in the fluorine-containing waste liquid also changes. However, since the solubility of metal hydroxide is constant with respect to a certain pH, the pH at which metal ions precipitate changes. However, the optimum pH for precipitating calcium fluoride-based particles in the calcium fluoride precipitation tank always changes, and a stable separation rate cannot be obtained.

これに対し、弗素イオン濃度の低いリンズ廃液に、弗素イオン濃度の高い酸廃液を少量ずつ一定量投入し弗素濃度変動の平準化を行うことが有効となる。より好ましくは、弗素イオン濃度の低いリンズ廃液と弗素イオン濃度の高い酸廃液を混合する原水調整槽において、弗素イオン濃度を弗素イオン電極にて連続的に測定しながら、弗素イオン濃度の高い酸廃液の投入量を制御し、弗素イオン濃度を一定に調整することがより有効である。または、弗素イオン濃度の低いリンズ廃液と弗素イオン濃度の高い酸廃液を、それぞれ弗素イオン電極にて連続測定を行い、それぞれの濃度から各廃液の混合比を決定することが有効である。   On the other hand, it is effective to equalize the fluorine concentration fluctuation by introducing a small amount of acid waste solution having a high fluorine ion concentration into the Linds waste solution having a low fluorine ion concentration little by little. More preferably, in a raw water adjustment tank in which a phosphorus waste solution having a low fluorine ion concentration and an acid waste solution having a high fluorine ion concentration are mixed, while measuring the fluorine ion concentration continuously with a fluorine ion electrode, the acid waste solution having a high fluorine ion concentration. It is more effective to control the amount of ion added to adjust the fluorine ion concentration to a constant value. Alternatively, it is effective to continuously measure the rinse waste liquid having a low fluorine ion concentration and the acid waste liquid having a high fluorine ion concentration with a fluorine ion electrode, and determining the mixing ratio of each waste liquid from the respective concentrations.

弗素濃度が著しく変化する３種類以上の弗素含有廃液を混合する場合においても、原水調製槽において、弗素イオン濃度を弗素イオン電極にて連続的に測定しながら、１つの弗素含有廃液の投入量を制御し、弗素イオン濃度を一定に調整することが有効である。または、それぞれの弗素含有廃液を、それぞれ弗素イオン電極にて連続測定を行い、それぞれの濃度から各廃液の混合比を決定することが有効である。   Even when mixing three or more types of fluorine-containing waste liquids with significant changes in the fluorine concentration, the amount of one fluorine-containing waste liquid to be fed is measured while continuously measuring the fluorine ion concentration at the fluorine ion electrode in the raw water preparation tank. It is effective to control and adjust the fluorine ion concentration to be constant. Alternatively, it is effective to continuously measure each fluorine-containing waste liquid at each fluorine ion electrode and determine the mixing ratio of each waste liquid from each concentration.

弗素イオン濃度が著しく変化する複数の弗素含有廃液を混合した混合液中の弗素イオン濃度を一定に制御しても、弗素イオン濃度に対する３価の鉄イオン濃度の比が変化すると、弗化カルシウム析出槽内のｐＨをある値に制御していても、弗化カルシウム主体の粒子の凝集体を含有するスラリーを固液分離によって生じる液体部の弗素イオン濃度も変化し、所定の弗素分離能力を安定的に維持できない。例えば、弗酸を含む酸でステンレス材を酸洗していくと、徐々に酸洗液中の３価の鉄イオン濃度が上昇する場合に起こる現象に相当する。   When the ratio of the trivalent iron ion concentration to the fluorine ion concentration changes even if the fluorine ion concentration in the mixed liquid in which a plurality of fluorine-containing waste liquids whose fluorine ion concentration changes remarkably is constant, the calcium fluoride precipitates. Even if the pH in the tank is controlled to a certain value, the fluorine ion concentration in the liquid part produced by solid-liquid separation of the slurry containing agglomerates of calcium fluoride-based particles also changes, stabilizing the prescribed fluorine separation ability Cannot be maintained. For example, when a stainless steel material is pickled with an acid containing hydrofluoric acid, this corresponds to a phenomenon that occurs when the concentration of trivalent iron ions in the pickling solution gradually increases.

これに対して、弗化カルシウム主体の粒子の凝集体を含有するスラリーを固液分離によって生じる液体部の弗素イオン濃度を連続又は間欠に測定し、その弗素イオン濃度の変動幅を±５０％以内に制御することが重要になる。制御方法としては、固液分離によって生じる液体部の弗素イオン濃度を弗素イオン電極にて連続又は間欠に測定し、カルシウムを含む物質の投入量を制御するのが良い。   On the other hand, the fluorine ion concentration in the liquid part produced by solid-liquid separation of the slurry containing the aggregate of calcium fluoride-based particles is measured continuously or intermittently, and the fluctuation range of the fluorine ion concentration is within ± 50%. It becomes important to control. As a control method, it is preferable to measure the concentration of fluorine ions in the liquid portion generated by solid-liquid separation continuously or intermittently with a fluorine ion electrode, and to control the amount of substance containing calcium.

制御時間間隔は、カルシウムを含む物質を投入する弗化カルシウム析出槽から液体部を得る固液分離までの水理学的滞留時間（通常１〜３時間）の１倍から３倍とするのが良い。具体的には、固液分離によって生じる液体部の弗素イオン濃度が設定値に対して差異がある場合、数時間から１０時間毎に、弗化カルシウム槽のｐＨを０．０５から０．５程度ずつ微調整を行うか、前記の酸の投入量を段階的に変化させるか、または、塩化カルシウム、石膏、硝酸カルシウムなどのカルシウムを含む塩の投入量を段階的に変化させるかが良い。このようにすることで、固液分離によって生じる液体部の弗素イオン濃度の変動幅を±５０％以内に制御することができる。   The control time interval is preferably 1 to 3 times the hydraulic residence time (usually 1 to 3 hours) from the calcium fluoride precipitation tank into which the substance containing calcium is charged to the solid-liquid separation to obtain the liquid part. . Specifically, when the fluorine ion concentration in the liquid portion generated by the solid-liquid separation is different from the set value, the pH of the calcium fluoride bath is about 0.05 to 0.5 every several hours to 10 hours. It may be finely adjusted each time, or the amount of acid input may be changed stepwise, or the amount of salt containing calcium such as calcium chloride, gypsum, calcium nitrate may be changed stepwise. By doing so, it is possible to control the fluctuation range of the fluorine ion concentration in the liquid portion caused by the solid-liquid separation within ± 50%.

カルシウムを含む物質が炭酸カルシウム、酸化カルシウム、水酸化カルシウムなどのアルカリ剤である場合には、酸もしくは廃酸を添加し、３価の鉄イオンが廃液中に存在しない場合、または、３価の鉄イオンが混入してもよい場合は、弗化カルシウム析出槽のｐＨを６以下に調整し、３価の鉄イオンの混入を低下させる場合は、ｐＨを３．７以下、より好ましくはｐＨ３．０以下にすることで、重金属イオンが析出するのを抑制することができる。酸としては、硫酸、塩酸、硝酸、酢酸などがあげられるが、石膏析出を伴う、硫酸の適用はあまり好ましくない。   When the substance containing calcium is an alkaline agent such as calcium carbonate, calcium oxide, calcium hydroxide, an acid or a waste acid is added, and when trivalent iron ions are not present in the waste liquid, or In the case where iron ions may be mixed, the pH of the calcium fluoride precipitation tank is adjusted to 6 or less, and in the case of reducing the mixing of trivalent iron ions, the pH is 3.7 or less, more preferably pH 3. By setting it to 0 or less, precipitation of heavy metal ions can be suppressed. Examples of the acid include sulfuric acid, hydrochloric acid, nitric acid, acetic acid, etc., but application of sulfuric acid with gypsum precipitation is not preferable.

弗化カルシウム析出槽で析出する弗化カルシウム主体の粒子の粒子径は、２００μｍ以下であり、粉砕した蛍石（例えば、０．３μｍ〜１ｍｍ）と比べ、粒子径が小さく比表面積が大きい。このため、弗化カルシウム析出槽で析出する弗化カルシウム主体の粒子は、蛍石と主成分が同じ弗化カルシウムであるため、金属精錬過程のスラグの滓化促進剤、あるいは、弗化水素酸の原料である蛍石の代替物として使用することができ、しかも、粉砕した蛍石より比表面積が大きいことより、反応性が良く、スラグの滓化時間の短縮や弗化水素酸の生成速度を上昇させることができる。   The particle size of the calcium fluoride-based particles deposited in the calcium fluoride precipitation tank is 200 μm or less, and the particle size is small and the specific surface area is large compared to pulverized fluorite (for example, 0.3 μm to 1 mm). For this reason, the calcium fluoride-based particles deposited in the calcium fluoride precipitation tank are the same calcium fluoride as the main component of fluorite. Therefore, the slag hatching accelerator in the metal refining process or hydrofluoric acid It can be used as a substitute for fluorite, which is a raw material of slag, and has a higher specific surface area than pulverized fluorite, so it has good reactivity, shortens the slag incubation time, and generates hydrofluoric acid Can be raised.

続いて、本発明を具体化した実施の形態について説明する。
図２には、本発明の弗素含有廃液の処理方法に係る処理装置の一例を示す。図２に示すように、本発明の一実施の形態に係る弗素含有廃液の処理方法に適用される処理装置１は、（１）原水調整工程、（２）弗素イオン析出工程、（３）重金属イオン析出工程、の３工程からなる。
まず、原水調整工程は、弗素イオン濃度の低いリンズ廃液２の投入量を制御するレベル計７とバルブ４と、弗素イオン濃度の高い濃厚な酸廃液３の投入量を制御する弗素イオン電極８とバルブ５と、原水調整槽６内を攪拌する攪拌機１０と、原水調整槽６内のｐＨを測定するｐＨ計９と、原水調整槽６内の弗素含有廃液を弗化カルシウム析出槽１２（弗素イオン析出工程）へ送るポンプ１１からなる。 Next, an embodiment embodying the present invention will be described.
In FIG. 2, an example of the processing apparatus which concerns on the processing method of the fluorine-containing waste liquid of this invention is shown. As shown in FIG. 2, the treatment apparatus 1 applied to the method for treating a fluorine-containing waste liquid according to an embodiment of the present invention includes (1) raw water adjustment step, (2) fluorine ion precipitation step, and (3) heavy metal. It consists of three steps, an ion precipitation step.
First, in the raw water adjustment step, a level meter 7 and a valve 4 for controlling the input amount of the phosphorus waste liquid 2 having a low fluorine ion concentration, and a fluorine ion electrode 8 for controlling the input amount of the concentrated acid waste liquid 3 having a high fluorine ion concentration A valve 5, a stirrer 10 for stirring the raw water adjustment tank 6, a pH meter 9 for measuring the pH in the raw water adjustment tank 6, and a fluorine-containing waste liquid in the raw water adjustment tank 6 are converted into a calcium fluoride precipitation tank 12 (fluorine ion The pump 11 is sent to the deposition step.

次の弗素イオン析出工程は、原水調整工程からの処理水を受け入れる弗化カルシウム析出槽１２と、弗化カルシウム析出槽１２内を循環する攪拌装置１３と、弗化カルシウム析出槽内のｐＨと弗素イオン濃度を測定するｐＨ計１５と、原水調整工程からの処理水中の弗素イオンを弗化カルシウムとするためにカルシウム源となるカルシウム剤を投入するバルブ１６と、弗化カルシウム析出槽内のｐＨを制御するｐＨ調整剤を投入するバルブ１７と、弗化カルシウム析出槽１２からのスラリーを受け入れ、凝集剤１９と混合する凝集槽１８と、凝集槽１８からのスラリーから液体部を分離する沈澱槽２０と、沈澱槽２０で分離した液体部中の弗素イオン濃度を測定する弗素イオン電極１４と、沈澱槽２０で回収した沈澱スラリーを弗化カルシウム析出槽１２へ送液するポンプ２１とからなる。沈殿槽２０で分離された液体は、次の金属析出工程へは自然流下で移送される。   The next fluorine ion precipitation step includes a calcium fluoride precipitation tank 12 that receives the treated water from the raw water adjustment step, a stirring device 13 that circulates in the calcium fluoride precipitation tank 12, and the pH and fluorine in the calcium fluoride precipitation tank. A pH meter 15 for measuring the ion concentration, a valve 16 for introducing a calcium agent as a calcium source in order to convert the fluoride ion in the treated water from the raw water adjustment step into calcium fluoride, and the pH in the calcium fluoride precipitation tank A valve 17 for introducing a pH adjusting agent to be controlled, a slurry from the calcium fluoride precipitation tank 12 and receiving a slurry from the calcium fluoride precipitation tank 12, and a precipitation tank 20 for separating the liquid part from the slurry from the aggregation tank 18. A fluorine ion electrode 14 for measuring the concentration of fluorine ions in the liquid portion separated in the precipitation tank 20, and the precipitate slurry recovered in the precipitation tank 20 as calcium fluoride. It consists pump 21 for feeding into the precipitation tank 12. The liquid separated in the precipitation tank 20 is transferred under natural flow to the next metal precipitation step.

最後の重金属析出工程は、弗素イオン析出工程からの処理水を受け入れる重金属析出槽２３と、重金属析出槽２３内を攪拌する攪拌装置２４と、重金属析出槽２３内のｐＨを測定するｐＨ計２５と、弗素イオン析出工程からの処理水のｐＨを制御するためのアルカリ剤を投入するバルブ２６と、重金属析出槽２３からのスラリーを受け入れ、凝集剤２７と混合する凝集槽２８と、凝集槽２８からのスラリーから液体部を分離する沈澱槽２９と、沈澱槽２９で回収した沈澱スラリーを重金属析出槽２３へ送液するポンプ３２とからなる。沈殿槽２９で分離された液体（処理水）は、配管３１により排水される。   The final heavy metal precipitation step includes a heavy metal precipitation vessel 23 that receives the treated water from the fluorine ion precipitation step, a stirring device 24 that stirs the heavy metal precipitation vessel 23, and a pH meter 25 that measures the pH in the heavy metal precipitation vessel 23. From the valve 26 for introducing an alkaline agent for controlling the pH of the treated water from the fluorine ion deposition step, the slurry from the heavy metal deposition tank 23 and receiving the slurry with the flocculant 27, and the aggregation tank 28 A precipitation tank 29 for separating the liquid portion from the slurry, and a pump 32 for feeding the precipitation slurry recovered in the precipitation tank 29 to the heavy metal precipitation tank 23. The liquid (treated water) separated in the settling tank 29 is drained through the pipe 31.

次に、図２に基づいて、本発明である弗素含有廃液の処理方法の一実施形態について説明する。
ステンレス鋼板を酸洗した際や、半導体製造工程のエッチング工程などで発生する弗化水素酸を含有した酸性液で、弗素イオン濃度の低いリンズ廃液２をバルブ４により、弗素イオン濃度の高い濃厚な酸廃液３をバルブ５により、原水調整槽６に投入する。原水調整槽６内のｐＨ計９および弗素イオン濃度計８でｐＨ値および弗素イオン濃度を連続して測定する。 Next, based on FIG. 2, one Embodiment of the processing method of the fluorine-containing waste liquid which is this invention is described.
An acid liquid containing hydrofluoric acid generated during pickling of stainless steel plates or etching processes in the semiconductor manufacturing process, and a rinse waste liquid 2 having a low fluorine ion concentration is concentrated with a high concentration of fluorine ions through a valve 4. The acid waste liquid 3 is put into the raw water adjustment tank 6 through a valve 5. The pH value and the fluorine ion concentration are continuously measured by the pH meter 9 and the fluorine ion concentration meter 8 in the raw water adjustment tank 6.

ステンレス鋼板を酸洗した際に発生する弗素イオン含有廃液は、ｐＨ１〜３で、弗素イオンを０．１〜３００ｇ／Ｌ含み、Ｆｅ、Ｃｒ、Ｎｉ等の金属を総量で１〜１００ｇ／Ｌ溶解しており、これらの金属のほとんどは金属イオンとして溶解して存在している。半導体製造工程のエッチング工程から排出される弗素イオン含有廃液は、ｐＨ１〜３で、弗素イオンを０．１〜３００ｇ／Ｌ含み、Ｓｉなどの元素を微量に含んでいる。   Fluorine ion-containing waste liquid generated when pickling stainless steel sheet is pH 1-3, contains 0.1-300 g / L of fluorine ions, and dissolves 1-100 g / L in total of metals such as Fe, Cr, Ni Most of these metals exist as dissolved metal ions. The fluorine ion-containing waste liquid discharged from the etching process of the semiconductor manufacturing process has a pH of 1 to 3, contains 0.1 to 300 g / L of fluorine ions, and contains trace amounts of elements such as Si.

ステンレス鋼板を酸洗した際に発生する弗素イオン含有廃液としては、通常、鋼板の酸洗した後の濃厚な酸廃液と、鋼板の表面に残存した酸を水で洗い流す際に発生するリンズ廃液がある。リンズ廃液中の弗素イオン濃度は１００〜３０００ｍｇ／Ｌで低濃度であるが、濃厚な酸廃液中の弗素イオン濃度は８０〜３００ｇ／Ｌ程度で高濃度であり、濃度差が非常に大きい。弗素イオン析出工程での弗素イオン除去率を一定にするためには、原水調整工程での弗素イオン濃度の平準化が重要であり、弗素イオン濃度の平均値に対する変動幅を±５０％以下、より好ましくは±２０％以下に平準化することが重要である。   Fluorine ion-containing waste liquid generated when pickling stainless steel sheets is usually concentrated acid waste liquid after pickling the steel sheet and rins waste liquid generated when the acid remaining on the steel sheet surface is washed away with water. is there. The concentration of fluorine ions in the waste liquor is 100 to 3000 mg / L, which is low, but the concentration of fluorine ions in the concentrated acid waste liquor is as high as about 80 to 300 g / L, and the concentration difference is very large. In order to make the fluorine ion removal rate constant in the fluorine ion precipitation step, it is important to level the fluorine ion concentration in the raw water adjustment step, and the fluctuation range with respect to the average value of the fluorine ion concentration is less than ± 50%. It is important that the leveling is preferably ± 20% or less.

そこで、弗素イオン濃度の低いリンズ廃液２に弗素イオン濃度の高い濃厚な酸廃液３をバルブ５を操作して少量切り出しにより投入したり、原水調整槽６内に設置している弗素イオン濃度計８の測定値で弗素イオン濃度の高い濃厚な酸廃液３の投入量をバルブ５で制御したりすることで、原水調整工程での弗素イオン濃度の平準化が可能である。   Accordingly, a concentrated acid waste liquid 3 having a high fluorine ion concentration is introduced into the Linds waste liquid 2 having a low fluorine ion concentration by operating the valve 5 to cut out a small amount, or a fluorine ion concentration meter 8 installed in the raw water adjustment tank 6. It is possible to level the fluorine ion concentration in the raw water adjustment step by controlling the amount of the concentrated acid waste liquid 3 having a high fluorine ion concentration with the valve 5 by the valve 5.

次に、原水調整槽６に連結したポンプ１１を作動して、原水調整槽６内の弗素イオン含有廃液を弗化カルシウム析出槽１２に投入する。沈澱槽２０からの処理水中の弗素イオン濃度を弗素イオン濃度計により、連続もしくは間欠に測定しながら、バルブ１６により弗化カルシウムとするためにカルシウム源となるカルシウム剤の投入量を制御し、弗素イオンを弗化カルシウムとして析出させる。また、弗化カルシウム析出槽内に塩酸、硫酸、硝酸、酢酸などの酸およびこれらを含む廃酸からなるｐＨ調整剤をバルブ１７により投入し、ｐＨを２．０〜３．７に制御することで、好ましくはｐＨを２．０〜３．０に制御することで、３価の鉄イオンを含む重金属イオンとの分離を促進することができる。   Next, the pump 11 connected to the raw water adjustment tank 6 is operated, and the fluorine ion-containing waste liquid in the raw water adjustment tank 6 is put into the calcium fluoride precipitation tank 12. While the fluorine ion concentration in the treated water from the precipitation tank 20 is continuously or intermittently measured with a fluorine ion concentration meter, the amount of calcium agent used as a calcium source is controlled by the valve 16 to obtain calcium fluoride. Ions are deposited as calcium fluoride. In addition, a pH adjusting agent made of acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid and waste acid containing these is introduced into the calcium fluoride precipitation tank through the valve 17 to control the pH to 2.0 to 3.7. Thus, preferably, by controlling the pH to 2.0 to 3.0, separation from heavy metal ions including trivalent iron ions can be promoted.

制御時間間隔は、カルシウムを含む物質を投入する弗化カルシウム析出槽から液体部を得る固液分離までの水理学的滞留時間（通常１〜３時間）の１倍から３倍とし、具体的には、数時間から１０時間毎に、弗化カルシウム槽のｐＨを０．０５から０．５程度ずつ微調整を行うか、あるいは、前記の酸の投入量を段階的に変化させるか、あるいは、塩化カルシウム、石膏、硝酸カルシウムなどのカルシウムを含む塩の投入量を段階的に変化させるかが良い。   The control time interval is 1 to 3 times the hydraulic residence time (usually 1 to 3 hours) from the calcium fluoride precipitation tank into which the substance containing calcium is charged to the solid-liquid separation to obtain the liquid part. Finely adjust the pH of the calcium fluoride bath by about 0.05 to 0.5 every few hours to 10 hours, or change the input amount of the acid stepwise, or The amount of salt containing calcium such as calcium chloride, gypsum, and calcium nitrate may be changed stepwise.

なお、弗化カルシウム析出槽内の水理学的滞留時間は５分〜６０分程度が妥当である。弗素イオンと３価の鉄イオンを分離せず、クロムイオンとニッケルイオンを弗素イオンから分離する場合、弗化カルシウム析出槽のｐＨは３．８〜６にする。析出した弗化カルシウムを含むスラリーは、弗化カルシウム析出槽１２から凝集槽１８に投入され、そこで、高分子凝集剤１９（アニオン系高分子凝集剤）を添加することにより凝集体を形成し、そのスラリーは沈澱槽２０に導き弗化カルシウムを主に含む粒子群は固体部として沈降し、液体部と固液分離を行う。   In addition, the hydraulic residence time in the calcium fluoride precipitation tank is appropriately about 5 to 60 minutes. In the case where chromium ions and nickel ions are separated from fluorine ions without separating fluorine ions and trivalent iron ions, the pH of the calcium fluoride precipitation tank is set to 3.8-6. The precipitated slurry containing calcium fluoride is charged into the agglomeration tank 18 from the calcium fluoride precipitation tank 12, where a polymer flocculant 19 (anionic polymer flocculant) is added to form an aggregate, The slurry is guided to the precipitation tank 20 and the particle group mainly containing calcium fluoride is settled as a solid part, and is separated from the liquid part.

沈降して固体部として分離した弗化カルシウムを主に含む粒子群をスラリーとしてポンプ２１によって弗化カルシウム析出槽１２に投入し、弗化カルシウム主体の粒子に、さらに、弗素イオンとカルシウムイオンを接触させて粒子径を増大化することができ、凝集体中の１つ１つの粒子は、当初、直径０．１μｍ以下の粒子であるが、０．３〜２００μｍの粒子にすることができる。なお、凝集槽の水理学的滞留時間は５〜１５分程度が妥当であり、沈澱槽のＯＦＲ（水表面積負荷）は、通常、２０〜１００ｍ／Ｄ程度が妥当である。   A particle group mainly containing calcium fluoride which has settled and separated as a solid part is put as slurry into a calcium fluoride precipitation tank 12 by a pump 21, and further, fluorine ions and calcium ions are brought into contact with calcium fluoride-based particles. The particle diameter can be increased, and each particle in the aggregate is initially a particle having a diameter of 0.1 μm or less, but can be a particle having a diameter of 0.3 to 200 μm. In addition, about 5 to 15 minutes is appropriate for the hydraulic residence time of the coagulation tank, and about 20 to 100 m / D is usually appropriate for the OFR (water surface area load) of the precipitation tank.

粒子径を大きくするには、弗化カルシウム析出槽、凝集槽、沈殿槽の容量にもよるが、ＳＲＴ（汚泥滞留時間）で数時間から数日程度かかる。沈澱槽２０から引抜かれるスラリーの一部を図示していない脱水機（フィルタープレス脱水機、真空脱水機、遠心分離機など)に投入し、脱水を行い、弗化カルシウム主体の脱水ケーキ作り、それを乾燥させて蛍石代替として利用する。また、重金属イオン混入量が少なく重金属イオンと分離する必要がない場合（例：半導体製造過程から排出される弗素イオンを含んだ排水）では、弗化カルシウム析出槽のｐＨを７〜９に制御することで、弗素イオンを含んだ排水中より弗素イオンを弗化カルシウムとして析出することができる。   To increase the particle size, depending on the capacity of the calcium fluoride precipitation tank, the coagulation tank, and the precipitation tank, it takes several hours to several days in SRT (sludge retention time). Part of the slurry withdrawn from the settling tank 20 is put into a dehydrator (not shown) (filter press dehydrator, vacuum dehydrator, centrifuge, etc.) and dehydrated to make a dehydrated cake mainly composed of calcium fluoride. Is used as a substitute for fluorite. In addition, when the amount of heavy metal ions is small and it is not necessary to separate heavy metal ions (eg, wastewater containing fluorine ions discharged from the semiconductor manufacturing process), the pH of the calcium fluoride precipitation tank is controlled to 7-9. Thus, fluorine ions can be precipitated as calcium fluoride from the waste water containing fluorine ions.

次に、重金属析出槽２３内には、沈澱槽２０で分離された液体部を連続して供給するとともに、第２回目の中和処理として、バルブ２６を作動して、苛性ソーダ、生石灰、消石灰、水酸化マグネシウムののうちの１種又は２種以上からなるアルカリ剤の水溶液又はスラリーを添加して、ｐＨを６以上１０以下の範囲に調整する。重金属析出槽２３内に設置している攪拌装置２４により重金属析出槽２３内を攪拌し、３価鉄イオンは水酸化鉄（ＩＩＩ）、３価のクロムイオンは水酸化クロム、ニッケルイオンは水酸化ニッケルとして析出し、水酸化金属主体の粒子になる。   Next, while continuously supplying the liquid portion separated in the precipitation tank 20 into the heavy metal precipitation tank 23, the valve 26 is operated as a second neutralization treatment, and caustic soda, quicklime, slaked lime, An aqueous solution or slurry of an alkaline agent composed of one or more of magnesium hydroxide is added to adjust the pH to a range of 6 to 10. The inside of the heavy metal precipitation tank 23 is stirred by a stirrer 24 installed in the heavy metal precipitation tank 23, the trivalent iron ion is iron (III) hydroxide, the trivalent chromium ion is chromium hydroxide, and the nickel ion is hydroxylated. It precipitates as nickel and becomes particles mainly composed of metal hydroxide.

重金属析出槽２３から排出された水酸化金属主体の粒子を含有するスラリーは、凝集槽２８において高分子凝集剤２７（アニオン系高分子凝集剤）によりフロックを形成し、その後、沈澱槽２９で液体部と固形部に分離され、液体部は放流される。固形部を再度、重金属析出槽２３に戻し、３価鉄イオンと３価クロムイオンおよび２価ニッケルイオンは、重金属析出槽２３に戻された固形部表面で析出し、水酸化金属主体の粒子は大きくなる。粒子径を大きくするには、重金属析出槽、凝集槽、沈殿槽の容量にもよるが、数時間から数日程度かかる。大きくなった水酸化金属主体の粒子を含むスラリーは、沈澱槽２９で分離し、一部、脱水機（フィルタープレス脱水機、真空脱水機、遠心分離機など）によって脱水し、弗素分が少ない水酸化金属主体の脱水ケーキを製造する。   The slurry containing the metal hydroxide-based particles discharged from the heavy metal precipitation tank 23 forms flocs with the polymer flocculant 27 (anionic polymer flocculant) in the coagulation tank 28, and then liquid in the precipitation tank 29. And the liquid part is discharged. The solid part is returned to the heavy metal precipitation tank 23 again, and trivalent iron ions, trivalent chromium ions and divalent nickel ions are precipitated on the surface of the solid part returned to the heavy metal precipitation tank 23. growing. To increase the particle size, depending on the capacity of the heavy metal precipitation tank, coagulation tank, and precipitation tank, it takes several hours to several days. The large slurry containing metal hydroxide-based particles is separated in the sedimentation tank 29 and partially dehydrated by a dehydrator (filter press dehydrator, vacuum dehydrator, centrifuge, etc.), and water containing less fluorine. Manufactures dehydrated cake mainly composed of metal oxide.

以下、実施例により本発明を詳細に説明する。
弗素イオン含有廃液であるリンズ廃液と濃厚な酸廃液として、表１に示すように、弗素イオン、３価鉄イオン、クロムイオン、ニッケルイオンを含み、大きく時間的に濃度変動がある弗素含有廃液を使用し、図２の処理装置を用いて、この弗素イオン含有廃液の処理を行った。原水調整槽、弗化カルシウム析出槽、重金属析出槽の容量はそれぞれ、３０Ｌ、６０Ｌ、６０Ｌであり、沈澱槽２０、２９の直径は６０ｃｍである。 Hereinafter, the present invention will be described in detail by way of examples.
As shown in Table 1, a fluorine-containing waste liquid containing fluorine ions, trivalent iron ions, chromium ions, nickel ions and having a large concentration fluctuation as shown in Table 1 as a phosphorus waste liquid and a concentrated acid waste liquid. The fluorine ion-containing waste liquid was treated using the treatment apparatus of FIG. The capacities of the raw water adjustment tank, calcium fluoride precipitation tank, and heavy metal precipitation tank are 30 L, 60 L, and 60 L, respectively, and the diameters of the precipitation tanks 20 and 29 are 60 cm.

Figure 2007196177
Figure 2007196177

原水調整槽６内に設置したレベル計７によってバルブ４を開閉し、リンズ廃液２を原水調整槽６に間欠に供給した。原水調整槽内６内に設置した弗素イオン電極８によって、原水調整槽６内の弗素イオン濃度が１２５０ｍｇ／Ｌになるように、バルブ５を開閉し、濃厚な酸廃液３を原水調整槽６に間欠に供給し、攪拌機１０によってリンズ廃液２と混合し、均一化した。ポンプ１１によって、原水調整槽６内の弗素含有廃液を弗化カルシウム析出槽１２に連続的に投入（２Ｌ／分）するとともに、弗化カルシウム析出槽内のｐＨを一定に３．０になるように、バルブ１７を操作し、酸化カルシウムスラリー（１００ｇ／Ｌ）を弗化カルシウム析出槽１２内に断続的に添加し、攪拌機１３で弗化カルシウム析出槽１２内を攪拌して弗素イオンを弗化カルシウムとして析出させながら、重金属類の析出を抑制した。   The valve 4 was opened and closed by a level meter 7 installed in the raw water adjustment tank 6, and the Linds waste liquid 2 was intermittently supplied to the raw water adjustment tank 6. The valve 5 is opened and closed by the fluorine ion electrode 8 installed in the raw water adjustment tank 6 so that the fluorine ion concentration in the raw water adjustment tank 6 becomes 1250 mg / L, and the concentrated acid waste liquid 3 is supplied to the raw water adjustment tank 6. It was supplied intermittently and mixed with the rinse waste liquid 2 by the stirrer 10 to make it uniform. The pump 11 continuously supplies the fluorine-containing waste liquid in the raw water adjustment tank 6 to the calcium fluoride precipitation tank 12 (2 L / min), and the pH in the calcium fluoride precipitation tank is kept constant at 3.0. In addition, the valve 17 is operated, and calcium oxide slurry (100 g / L) is intermittently added to the calcium fluoride precipitation tank 12, and the inside of the calcium fluoride precipitation tank 12 is stirred by the stirrer 13 to fluorinate fluorine ions. While precipitating as calcium, precipitation of heavy metals was suppressed.

弗化カルシウム析出槽１２からでるスラリーに高分子凝集剤１９（アニオン系高分子凝集材）を凝集槽１８で添加しフロックとした後、沈澱槽２０で固液分離を行った。沈澱したスラリーはポンプ２１によって、再度、弗化カルシウム析出槽１２へ５００ｍｌ／分（スラリー濃度２７０〜３３０ｇ／Ｌ）で戻し、析出する弗化カルシウムを主体に含む粒子の粒子径を増大化した。この際、弗化カルシウム主体の粒子の凝集体を生成する弗化カルシウム析出槽内の固形物量をＡ（ｋｇ）とし、新たに析出した弗化カルシウム主体の固形物量をＢ（ｋｇ／日）としたとき、
Ａ÷Ｂは０．５〜０．６（日）となった。 A polymer flocculant 19 (anionic polymer flocculant) was added to the slurry from the calcium fluoride precipitation tank 12 in a flocculent tank 18 to form a floc, and solid-liquid separation was performed in the precipitation tank 20. The precipitated slurry was returned again by the pump 21 to the calcium fluoride precipitation tank 12 at 500 ml / min (slurry concentration 270 to 330 g / L), and the particle size of the particles mainly containing precipitated calcium fluoride was increased. At this time, the amount of solids in the calcium fluoride precipitation tank that generates aggregates of calcium fluoride-based particles is A (kg), and the amount of newly precipitated calcium fluoride-based solids is B (kg / day). When
A ÷ B was 0.5 to 0.6 (day).

間欠的に、沈澱槽２０で回収したスラリーの一部を配管２２から抜き出し、０．５ＭＰａの加圧力を有するフィルタープレス脱水機で脱水して、脱水ケーキ（弗化カルシウム系ケーキ）とした。沈澱槽２０からの処理水を一部採水し、弗素イオン電極１４によって連続測定し、弗素イオン濃度が１９０ｍｇ／Ｌとなるように、弗化カルシウム析出槽１２に希塩酸を連続投入した。希塩酸の投入量の変化は、弗化カルシウム析出槽１２から沈澱槽２０までのタイムラグである６時間ごとに微調整した。   Intermittently, a part of the slurry collected in the precipitation tank 20 was extracted from the pipe 22 and dehydrated with a filter press dehydrator having a pressure of 0.5 MPa to obtain a dehydrated cake (calcium fluoride-based cake). A portion of the treated water from the precipitation tank 20 was sampled and continuously measured with the fluorine ion electrode 14, and dilute hydrochloric acid was continuously added to the calcium fluoride precipitation tank 12 so that the fluorine ion concentration was 190 mg / L. The change in the amount of dilute hydrochloric acid was finely adjusted every 6 hours, which is the time lag from the calcium fluoride precipitation tank 12 to the precipitation tank 20.

沈澱槽２０で分離した処理水（液体部）を、自然流下で重金属析出槽２３に投入し、バルブ２６を操作することによって酸化カルシウムスラリー（１００ｇ／Ｌ）を投入し、重金属析出槽内のｐＨを８に維持した。重金属析出槽２３内は攪拌装置２４により攪拌している。重金属析出槽２３内からのスラリーに高分子凝集剤２７を凝集槽２８で添加しフロックとした後、沈澱槽２９で固液分離を行った。沈澱したスラリーはポンプ３２によって、再度、重金属析出槽４０へ５００ｍｌ／分(スラリー濃度２３０〜２８５ｇ／Ｌ）で戻して、析出する水酸化金属を主体に含む粒子の粒子径を増大化した。   The treated water (liquid part) separated in the precipitation tank 20 is charged into the heavy metal precipitation tank 23 under a natural flow, and the calcium oxide slurry (100 g / L) is charged by operating the valve 26 to adjust the pH in the heavy metal precipitation tank. Was maintained at 8. The heavy metal precipitation tank 23 is stirred by a stirring device 24. Polymer flocculant 27 was added to the slurry from inside heavy metal precipitation tank 23 in flocculent tank 28 to form a floc, and solid-liquid separation was performed in precipitation tank 29. The precipitated slurry was returned again to the heavy metal precipitation tank 40 by the pump 32 at 500 ml / min (slurry concentration 230 to 285 g / L), and the particle diameter of particles mainly containing precipitated metal hydroxide was increased.

この際、水酸化金属主体の粒子の凝集体を生成する重金属析出槽内の固形物量をＡ（ｋｇ）とし、新たに析出した水酸化金属主体の固形物量をＢ（ｋｇ／日）としたとき、
Ａ÷Ｂは０．９〜１．１（日）となった。
間欠的に、沈澱槽２９で回収したスラリーの一部を配管３０から抜き出し、０．５ＭＰａ（ゲージ圧）の加圧力を有するフィルタープレス脱水機で脱水して、脱水ケーキ（水酸化金属系ケーキ）とした。この際の原水調整槽６からの処理水質、弗化カルシウム析出工程の沈澱槽２０からの処理水質、重金属析出工程の沈澱槽２９からの処理水質を表２に、弗化カルシウム系ケーキと水酸化金属系ケーキの成分を表３に示す。 At this time, when the amount of solids in the heavy metal precipitation tank that generates aggregates of metal hydroxide-based particles is A (kg) and the amount of newly precipitated metal hydroxide-based solids is B (kg / day) ,
A / B was 0.9 to 1.1 (days).
Intermittently, a part of the slurry collected in the precipitation tank 29 is extracted from the pipe 30 and dehydrated with a filter press dehydrator having a pressure of 0.5 MPa (gauge pressure) to obtain a dehydrated cake (metal hydroxide type cake) It was. Table 2 shows the quality of the treated water from the raw water adjustment tank 6, the quality of the treated water from the precipitation tank 20 in the calcium fluoride precipitation process, and the quality of the treated water from the precipitation tank 29 in the heavy metal precipitation process. Table 3 shows the components of the metal cake.

原水調整槽６からの処理水中の弗素濃度の平均値に対する変動率は約±１５％に抑制し、それに伴い、重金属濃度の変動も抑制でき、その結果、沈殿槽２０からの処理水のＳＳ（浮遊物質濃度）を１０〜２０ｍｇ／Ｌと抑制でき、かつ、弗化カルシウム析出槽１２において、原水調整槽６からの処理水中の弗素イオン、３価の鉄イオン、クロムイオン、ニッケルイオンは、それぞれ、おおよそ８５％、２０％、４％、２％析出し、鉄の析出を抑制しながら弗素イオンを分離することができた。弗化カルシウム系ケーキ中の弗化カルシウム量は約９５％になり、重金属系脱水ケーキ中の弗素濃度は低下し、重金属濃度が相対的に増加し、ステンレス原料として利用できる成分組成になった。また、弗化カルシウム析出槽および重金属析出槽中の粒子径は、それぞれ１〜８５μｍ、１〜２７μｍであり増大化した。その結果、脱水後の水分は低下した。   The fluctuation rate with respect to the average value of the fluorine concentration in the treated water from the raw water adjustment tank 6 is suppressed to about ± 15%, and accordingly, the fluctuation of the heavy metal concentration can also be suppressed. As a result, the SS ( (Floating substance concentration) can be suppressed to 10 to 20 mg / L, and in the calcium fluoride precipitation tank 12, fluorine ions, trivalent iron ions, chromium ions and nickel ions in the treated water from the raw water adjustment tank 6 are respectively About 85%, 20%, 4%, and 2% were precipitated, and fluorine ions could be separated while suppressing the precipitation of iron. The amount of calcium fluoride in the calcium fluoride cake was about 95%, the fluorine concentration in the heavy metal dehydrated cake was lowered, the heavy metal concentration was relatively increased, and a component composition that can be used as a stainless steel raw material was obtained. The particle sizes in the calcium fluoride precipitation tank and the heavy metal precipitation tank were 1 to 85 μm and 1 to 27 μm, respectively, and increased. As a result, the water content after dehydration decreased.

Figure 2007196177
Figure 2007196177

Figure 2007196177
Figure 2007196177

原水調整槽６内で弗素イオン濃度制御を実施せずに、リンズ廃液に濃厚な酸廃液を少量ずつ切り出して混合した場合、原水調整槽６からの処理水中の弗素濃度は大きく振れ、弗素濃度の平均値に対する変動率は約１２０％にも達し、それに伴い、重金属濃度の変動も抑制できず、その結果、沈殿槽２０からの処理水のＳＳは３００〜５００ｍｇ／Ｌと高くなり、重金属系ケーキ中（固形物成分）の弗素成分およびカルシウム成分はそれぞれ２４％、２６％にもなり、原水調整槽６における弗素イオン濃度制御の重要性が証明できた。   If the concentrated acid waste solution is cut out and mixed with the Linds waste solution little by little without controlling the fluorine ion concentration in the raw water adjustment tank 6, the fluorine concentration in the treated water from the raw water adjustment tank 6 fluctuates greatly. The fluctuation rate with respect to the average value reaches about 120%, and accordingly, the fluctuation of the heavy metal concentration cannot be suppressed. As a result, the SS of the treated water from the precipitation tank 20 becomes as high as 300 to 500 mg / L, and the heavy metal cake The fluorine component and calcium component in the middle (solid component) were 24% and 26%, respectively, demonstrating the importance of controlling the fluorine ion concentration in the raw water adjustment tank 6.

ｐＨと弗化カルシウムの溶解度積の関係を示す図である。It is a figure which shows the relationship between pH and the solubility product of calcium fluoride. 弗素含有排水の処理方法に供する装置の１例を示す図である。It is a figure which shows one example of the apparatus used for the processing method of fluorine-containing waste_water | drain.

符号の説明Explanation of symbols

１ 弗素含有廃液の処理装置
２ リンズ廃液
３ 濃厚な酸廃液
４ バルブ（リンズ廃液投入用）
５ バルブ（濃厚な酸廃液投入用）
６ 原水調整槽
７ レベル計
８ 弗素イオン電極
９ ｐＨ計
１０ 攪拌機
１１ ポンプ
１２ 弗化カルシウム析出槽
１３ 攪拌機
１４ 弗素イオン電極
１５ ｐＨ計
１６ バルブ（ｐＨ調整剤投入量）
１７ バルブ（カルシウム源投入用）
１８ 凝集槽
１９ 高分子凝集剤
２０ 沈澱槽
２１ ポンプ
２２ 配管
２３ 重金属析出槽
２４ 攪拌装置
２５ ｐＨ計
２６ バルブ（アルカリ剤投入用）
２７ 高分子凝集剤
２８ 凝集槽
２９ 沈澱槽
３０ 配管
３１ 処理水
３２ ポンプ


特許出願人 新日鐵住金ステンレス株式会社
代理人 弁理士 椎 名 彊 他１名


1 Fluorine-containing waste liquid treatment equipment 2 Linds waste liquid 3 Concentrated acid waste liquid 4 Valve (for Linds waste liquid input)
5 Valve (for charging thick acid waste liquid)
6 Raw water adjustment tank 7 Level meter 8 Fluorine ion electrode 9 pH meter 10 Stirrer 11 Pump 12 Calcium fluoride precipitation tank 13 Stirrer 14 Fluorine ion electrode 15 pH meter 16 Valve (pH adjuster input amount)
17 Valve (for calcium source input)
18 Coagulation tank 19 Polymer flocculant 20 Precipitation tank 21 Pump 22 Piping 23 Heavy metal precipitation tank 24 Stirrer 25 pH meter 26 Valve (for adding alkali agent)
27 Polymer flocculant 28 Coagulation tank 29 Precipitation tank 30 Piping 31 Treated water 32 Pump


Patent Applicant Nippon Steel & Sumikin Stainless Steel Corporation
Attorney Attorney Shiina and one other


Claims (11)

弗素イオンと重金属イオンを含有する弗素含有廃液に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子を析出させる工程と、前記工程の処理液に高分子凝集剤を添加して、弗化カルシウム主体の粒子の凝集体を生成する工程と、前記凝集体を生成する工程の処理液を固液分離して、弗化カルシウム主体の粒子を固体部として回収する工程とを有し、前記回収した固体部の一部を前記弗化カルシウム主体の粒子を析出させる工程に投入し、固体部中の弗化カルシウム主体の粒子に、更に弗化カルシウムを析出させて粒子径を増大化し、当該増大化した弗化カルシウム主体の粒子を前記固液分離により固体部として回収することを特徴とする弗素含有廃液の処理方法。   Adding a substance containing calcium to a fluorine-containing waste liquid containing fluorine ions and heavy metal ions to precipitate calcium fluoride-based particles; and adding a polymer flocculant to the treatment liquid of the above-mentioned process; A step of generating an aggregate of calcium fluoride-based particles, and a step of solid-liquid separation of the treatment liquid of the step of generating the aggregate to recover the calcium fluoride-based particles as a solid part, A portion of the recovered solid portion is put into the step of precipitating the calcium fluoride-based particles, and calcium fluoride is further precipitated on the calcium fluoride-based particles in the solid portion to increase the particle diameter. A method for treating a fluorine-containing waste liquid, wherein the increased calcium fluoride-based particles are recovered as a solid part by the solid-liquid separation. 前記回収した弗化カルシウム主体の粒子からなる固体部の一部を前記弗化カルシウム主体の粒子を析出させる工程に投入する際に、弗化カルシウム主体の粒子を析出させる工程内の固形物量をＡ（ｋｇ）とし、弗素イオンと重金属イオンを含有する弗素含有廃液に、カルシウムを含む物質を添加して、弗化カルシウム主体の粒子が新たに析出する量をＢ（ｋｇ／日）としたとき、Ａ÷Ｂを０．０５（日）以上、１．０（日）以下にすることを特徴とする請求項１記載の弗素含有廃液の処理方法。   When a part of the collected solid portion composed of calcium fluoride-based particles is added to the step of precipitating calcium fluoride-based particles, the amount of solids in the step of precipitating calcium fluoride-based particles is defined as A (Kg), when a substance containing calcium is added to a fluorine-containing waste liquid containing fluorine ions and heavy metal ions, and the amount of newly precipitated calcium fluoride-based particles is B (kg / day), 2. The method for treating a fluorine-containing waste liquid according to claim 1, wherein A / B is 0.05 (day) or more and 1.0 (day) or less. 前記固液分離によって固体部と分離される重金属イオンを含む液体部を、ｐＨ６超１０以下に調整して重金属主体の粒子を析出させる工程と、当該重金属主体の粒子を析出させる工程の処理液に高分子凝集剤を添加して、重金属主体の粒子の凝集体を生成する工程と、当該重金属主体の凝集体を生成する工程の処理液を固液分離によって重金属主体の粒子を固体部として回収する工程とを更に有することを特徴とする請求項１または２に記載の弗素含有廃液の処理方法。   The liquid part containing heavy metal ions separated from the solid part by the solid-liquid separation is adjusted to pH 6 to 10 or less to precipitate heavy metal-based particles, and the treatment liquid of the heavy metal-based particles is precipitated. The heavy metal-based particles are recovered as a solid part by solid-liquid separation of the treatment liquid of the step of adding a polymer flocculant to generate aggregates of heavy metal-based particles and the step of generating the heavy metal-based aggregates. The method for treating a fluorine-containing waste liquid according to claim 1 or 2, further comprising a step. 前記金属イオンにＣｒ3+、Ｎｉ2+の少なくともいずれかを含む場合、前記弗化カルシウム主体の粒子を析出させる際のｐＨ調整をｐＨ３．８以上６以下とすることを特徴とする請求項１または２に記載の弗素含有廃液の処理方法。 2. When the metal ion contains at least one of Cr 3+ and Ni 2+ , pH adjustment when the calcium fluoride-based particles are precipitated is adjusted to pH 3.8 or more and 6 or less. Or the processing method of the fluorine-containing waste liquid of 2. 前記金属イオンにＦｅ3+を含む場合、前記弗化カルシウム主体の粒子を析出させる際のｐＨ調整をｐＨ２．０以上３．７以下とすることを特徴とする請求項１または２に記載の弗素含有廃液の処理方法。 3. The fluorine according to claim 1, wherein, when Fe 3+ is contained in the metal ion, the pH adjustment when the calcium fluoride-based particles are precipitated is set to pH 2.0 or more and 3.7 or less. Treatment method for waste liquid. 前記回収した重金属主体の固体部の一部を前記重金属主体の粒子を析出させる工程に投入し、固体部中の重金属主体の粒子に、更に重金属イオンを接触させて粒子径を増大化し、当該増大化した重金属主体の粒子を固液分離により回収することを特徴とする請求項１〜５のいずれか１項に記載の弗素含有廃液の処理方法。   Part of the recovered heavy metal-based solid part is added to the step of precipitating the heavy metal-based particles, and the heavy metal ions in the solid part are further brought into contact with heavy metal ions to increase the particle size. 6. The method for treating a fluorine-containing waste liquid according to any one of claims 1 to 5, wherein the converted heavy metal-based particles are recovered by solid-liquid separation. 弗素イオンと重金属イオンを含有する弗素濃度の異なる２種類以上の弗素含有廃液を混合して処理する場合、弗素イオン電極を用いて、混合後の弗素含有廃液中に含まれる弗素イオン濃度の変動幅を±５０％以内に制御することを特徴とする請求項１〜６のいずれか１項に記載の弗素含有廃液の処理方法。   When two or more types of fluorine-containing waste liquids containing fluorine ions and heavy metal ions with different concentrations are mixed and processed, using a fluorine ion electrode, the fluctuation range of the fluorine ion concentration contained in the fluorine-containing waste liquid after mixing The fluorine-containing waste liquid treatment method according to any one of claims 1 to 6, wherein: 弗化カルシウム主体の粒子の凝集体を生成する工程での処理液を、固液分離した後の液体部の弗素イオン濃度を連続又は間欠に測定し、当該測定濃度に応じて弗化カルシウム主体の粒子を析出させる工程へ投入するカルシウムを含む物質の投入量を制御することで、その弗素イオン濃度の変動幅を±５０％以内に制御することを特徴とする請求項１〜７のいずれか１項に記載の弗素含有廃液の処理方法。   Measure the fluorine ion concentration in the liquid part after solid-liquid separation of the treatment liquid in the step of forming the aggregate of calcium fluoride-based particles, and measure the concentration of fluorine ions based on the measured concentration. 8. The fluctuation range of the fluorine ion concentration is controlled within ± 50% by controlling the amount of the substance containing calcium to be introduced into the step of precipitating the particles. A method for treating a fluorine-containing waste liquid as described in the above item. 前記固液分離して固体部として回収した弗化カルシウム主体の粒子を、金属精錬過程のスラグの滓化促進剤、又は弗化水素酸の原料である蛍石の代替物として使用することを特徴とする請求項１〜８のいずれか１項に記載の弗素含有廃液の処理方法。   The calcium fluoride-based particles recovered as a solid part after the solid-liquid separation are used as a slag hatching accelerator in a metal refining process or as a substitute for fluorite, which is a raw material of hydrofluoric acid. The method for treating a fluorine-containing waste liquid according to any one of claims 1 to 8. 前記固液分離して固体部として回収した重金属主体の粒子を、ステンレス原料、又は合金鉄原料として使用することを特徴とする請求項３〜９のいずれか１項に記載の弗素含有廃液の処理方法。   The treatment of a fluorine-containing waste liquid according to any one of claims 3 to 9, wherein the heavy metal-based particles recovered as a solid part by solid-liquid separation are used as a stainless steel raw material or an iron alloy raw material. Method. 前記添加するカルシウムを含む物質が、酸化カルシウム、水酸化カルシウム、炭酸カルシウムのうちの１種又は２種以上であることを特徴とする請求項１〜１０のいずれか１項に記載の弗素含有廃液の処理方法。   The fluorine-containing waste liquid according to any one of claims 1 to 10, wherein the substance containing calcium to be added is one or more of calcium oxide, calcium hydroxide, and calcium carbonate. Processing method.
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Cited By (11)

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