JP2019181328A - Method for removing fluorine - Google Patents
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本発明は、例えば非鉄金属製錬工程から生じる硫酸イオン及びマグネシウムを含むフッ素含有排水からのフッ素除去方法に関する。 The present invention relates to a method for removing fluorine from fluorine-containing wastewater containing sulfate ions and magnesium, for example, generated from a nonferrous metal smelting process.
銅や鉛等の非鉄金属の製錬工程では、原料鉱石を炉に投入して熔解し、不純物をスラグとして、又は硫黄を亜硫酸ガスとして分離し、目的とする金属を精製する。原料鉱石にはフッ素が含有されることがあるが、このフッ素は鉱石が熔解される際に揮発し、亜硫酸ガスと共に排ガスとしてスクラバー等に集められ、アルカリ性の洗浄液中に捕集される。 In the smelting process of non-ferrous metals such as copper and lead, raw ore is put into a furnace and melted, and impurities are separated as slag or sulfur as sulfurous acid gas to purify the target metal. The raw ore may contain fluorine, but the fluorine volatilizes when the ore is melted, and is collected together with sulfurous acid gas as an exhaust gas in a scrubber or the like and collected in an alkaline cleaning liquid.
スクラバー等で排ガスを捕集した洗浄液は、洗浄廃液として順次取り出されて処理され、フッ素が分離回収される。フッ素を除去した後の洗浄廃液は、引き続いて排水処理施設に送られ、一般の排水と共に中和、酸化、還元等の方法によって、重金属や有機物等を分離し、無害化された後に排出される。 The cleaning liquid in which the exhaust gas is collected by a scrubber or the like is sequentially taken out and processed as cleaning waste liquid, and fluorine is separated and recovered. The cleaning waste liquid after the removal of fluorine is subsequently sent to a wastewater treatment facility, where it is neutralized, oxidized, reduced, etc. along with general wastewater, separated from heavy metals and organic matter, and discharged after detoxification. .
排水等の水溶液中に含まれるフッ素を除去する一般的な方法としては、フッ素沈澱剤として消石灰や塩化カルシウムや硫酸カルシウム等のカルシウム化合物を添加し、フッ素を難溶性のフッ化カルシウムとして沈澱させる方法が知られている。 As a general method for removing fluorine contained in an aqueous solution such as waste water, a method of adding calcium compounds such as slaked lime, calcium chloride, and calcium sulfate as a fluorine precipitating agent to precipitate fluorine as poorly soluble calcium fluoride. It has been known.
例えば特許文献１には、フッ素含有排水中の硫酸イオン濃度を調整する硫酸イオン濃度調整工程と、フッ素含有排水中のフッ素を沈澱として分離除去するフッ素沈澱除去工程とを含むフッ素含有排水中のフッ素をフッ化カルシウムとして沈澱させて分離除去するフッ素含有排水からのフッ素分離方法が記載されている。 For example, Patent Document 1 discloses fluorine in fluorine-containing wastewater including a sulfate ion concentration adjusting step for adjusting the sulfate ion concentration in fluorine-containing wastewater, and a fluorine precipitation removing step for separating and removing fluorine in the fluorine-containing wastewater as a precipitate. Describes a method for separating fluorine from fluorine-containing wastewater by precipitating and separating it as calcium fluoride.
しかし、特許文献１に記載の方法によれば、硫酸イオン濃度を調整するために、フッ素含有排水に多量の塩化カルシウムを添加する必要があり、コストアップにつながっていた。また、フッ素含有排水中のマグネシウム濃度が大きい場合はマグネシウム濃度調整工程が必要であり、コストアップにつながっていた。また、マグネシウム濃度調整工程及びフッ素沈澱除去工程では硫酸カルシウムを含むスラッジが発生するため、スラッジ処理のコストアップにつながっていた。 However, according to the method described in Patent Document 1, in order to adjust the sulfate ion concentration, it is necessary to add a large amount of calcium chloride to the fluorine-containing waste water, leading to an increase in cost. In addition, when the concentration of magnesium in the fluorine-containing wastewater is large, a magnesium concentration adjustment step is necessary, leading to an increase in cost. Further, in the magnesium concentration adjusting step and the fluorine precipitation removing step, sludge containing calcium sulfate is generated, leading to an increase in the cost of sludge treatment.
本発明は、上述した従来の事情に鑑みて提案されたものであり、非鉄金属製錬工程から生じるフッ素含有排水から簡単且つ低コストで効率よくフッ素を分離除去することができ、しかも、硫酸イオン濃度及びマグネシウム濃度を調整することなく、常に安定して確実なフッ素の分離除去が可能な方法を提供することを目的とする。 The present invention has been proposed in view of the above-mentioned conventional circumstances, and can separate and remove fluorine easily and at low cost from fluorine-containing wastewater generated from a nonferrous metal smelting process. It is an object of the present invention to provide a method capable of always and stably separating and removing fluorine without adjusting the concentration and the magnesium concentration.
本発明者等は、硫酸イオン及びマグネシウムを含む、非鉄金属製錬工程から生じるフッ素含有排水中（以下、「フッ素含有排水」とも言う）において、硫酸イオンの溶解度を安定させ排水中のフッ素を低減する処理方法について検討を重ね、フッ素含有排水にリン酸を一定の範囲の割合で添加した後に消石灰を一定の範囲の割合で添加することで、フッ素が安定的に分離されることを見出し、本発明を完成させるに至った。 The present inventors stabilize sulfate ion solubility and reduce fluorine in wastewater in fluorine-containing wastewater containing non-ferrous metal smelting process containing sulfate ions and magnesium (hereinafter also referred to as “fluorine-containing wastewater”). The treatment method was repeated, and it was found that fluorine was stably separated by adding phosphoric acid to the fluorine-containing wastewater in a certain range and then adding slaked lime in a certain range. The invention has been completed.
即ち、上記目的を達成するための本発明の一態様は、非鉄金属製錬工程から生じる硫酸イオン及びマグネシウムを含むフッ素含有排水からのフッ素除去方法であって、前記フッ素含有排水にリン酸を添加するリン酸添加工程と、前記リン酸添加工程後のフッ素含有排水に消石灰を添加して、生成したフッ素含有沈澱物を分離除去するフッ素沈澱除去工程とを有することを特徴とする。 That is, one aspect of the present invention for achieving the above object is a method for removing fluorine from fluorine-containing wastewater containing sulfate ions and magnesium generated from a non-ferrous metal smelting process, wherein phosphoric acid is added to the fluorine-containing wastewater. And adding a slaked lime to the fluorine-containing waste water after the phosphoric acid addition step to separate and remove the generated fluorine-containing precipitate.
このようにすれば、フッ素含有排水中の硫酸イオン濃度及びマグネシウム濃度を調整することなく、常に安定して確実にフッ素を分離除去することができる。また、非鉄金属製錬工程から生じる硫酸イオン及びマグネシウムを含むフッ素含有排水から簡単且つ低コストで効率よくフッ素を分離除去することができる。 In this way, it is possible to always and stably separate and remove fluorine without adjusting the sulfate ion concentration and the magnesium concentration in the fluorine-containing waste water. Further, fluorine can be separated and removed easily and at low cost from fluorine-containing wastewater containing sulfate ions and magnesium generated from the nonferrous metal smelting process.
また、本発明の一態様では、前記フッ素含有沈澱物はフッ化アパタイトを含有してもよい。 In one embodiment of the present invention, the fluorine-containing precipitate may contain fluorinated apatite.
このようにすれば、フッ素含有排水中の硫酸イオン濃度及びマグネシウム濃度を調整することなく、常に安定して確実にフッ素を分離除去することができる。 In this way, it is possible to always and stably separate and remove fluorine without adjusting the sulfate ion concentration and the magnesium concentration in the fluorine-containing waste water.
また、本発明の一態様では、前記リン酸の添加量を、前記フッ素含有排水中のフッ素（Ｆ）に対する前記リン酸中のリン（Ｐ）のモル比（Ｐ／Ｆ）が０．２以上５．０以下となるように調整してもよい。 In one embodiment of the present invention, the addition amount of the phosphoric acid is such that the molar ratio (P / F) of phosphorus (P) in the phosphoric acid to fluorine (F) in the fluorine-containing wastewater is 0.2 or more. You may adjust so that it may be 5.0 or less.
このようにすれば、フッ素含有排水に添加するリン酸のコストを抑えつつ、フッ素の沈澱量を増加させることができる。 If it does in this way, the amount of precipitation of fluorine can be increased, suppressing the cost of phosphoric acid added to fluorine content drainage.
また、本発明の一態様では、前記消石灰の添加量を、前記フッ素含有排水中のリン（Ｐ）に対する該消石灰中のカルシウム（Ｃａ）のモル比（Ｃａ／Ｐ）が１．６７以上、２．００以下となるように調整してもよい。 Moreover, in 1 aspect of this invention, the molar ratio (Ca / P) of the calcium (Ca) in this slaked lime with respect to the phosphorus (P) in the said fluorine-containing waste water is 1.67 or more. You may adjust so that it may become 0.00 or less.
このようにすれば、フッ素含有排水からフッ素を除去したフッ素除去排水中のリン濃度の上昇による環境への悪影響を抑えつつ、フッ素の除去効果を高くすることができる。 If it does in this way, the removal effect of fluorine can be heightened, suppressing the bad influence to the environment by the raise of the phosphorus concentration in the fluorine removal waste_water | drain which removed the fluorine from fluorine-containing waste_water | drain.
本発明によれば、非鉄金属製錬工程から生じる硫酸イオン及びマグネシウムを含むフッ素含有排水から簡単且つ低コストで効率よくフッ素を分離除去することができ、しかも硫酸イオン濃度及びマグネシウム濃度を調整することなく、常に安定して確実にフッ素を分離除去することができる。 According to the present invention, fluorine can be easily and efficiently separated and removed from fluorine-containing wastewater containing sulfate ions and magnesium generated from a nonferrous metal smelting process, and the sulfate ion concentration and the magnesium concentration can be adjusted. Therefore, fluorine can be separated and removed constantly and reliably.
本発明を適用した具体的な実施の形態（以下、「本実施の形態」という。）について、以下の順序で図面を参照して詳細に説明する。なお、本発明は、以下の実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々の変更を加えることが可能である。 A specific embodiment to which the present invention is applied (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings in the following order. Note that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention.
１．フッ素含有排水からのフッ素除去方法
１−１．フッ素除去方法の概要
１−２．各工程の概略
１−３．リン酸添加工程
１−４．フッ素沈澱除去工程
1. Method for removing fluorine from fluorine-containing waste water 1-1. Outline of fluorine removal method 1-2. Outline of each process 1-3. Phosphoric acid addition process 1-4. Fluorine precipitation removal process
［１．フッ素含有排水からのフッ素除去方法］
（１−１．フッ素除去方法の概要）
本実施の形態に係るフッ素含有排水からのフッ素除去方法（以下、「フッ素除去方法」という。）は、銅や鉛等の非鉄金属の製錬工程（非鉄金属製錬工程）から生じる排水中に含まれている原料鉱石由来のフッ素を除去する方法である。
[1. Method of removing fluorine from fluorine-containing wastewater]
(1-1. Overview of fluorine removal method)
The fluorine removal method (hereinafter referred to as “fluorine removal method”) from fluorine-containing wastewater according to the present embodiment is used in wastewater generated from a smelting process (nonferrous metal smelting process) of nonferrous metals such as copper and lead. This is a method for removing fluorine derived from the raw material ore included.
非鉄金属の製錬においては、原料鉱石の熔解時に発生する排ガス中に含まれているフッ素や亜硫酸ガスをスクラバーで捕集して処理を行う。排ガス中のフッ素をスクラバーで捕集するとフッ素含有排水が得られる。 In the smelting of non-ferrous metals, the scrubber collects fluorine and sulfurous acid gas contained in the exhaust gas generated during melting of the raw ore. When fluorine in exhaust gas is collected with a scrubber, fluorine-containing wastewater is obtained.
また、排ガス中の亜硫酸ガスをスクラバーで捕集すると硫酸イオンが得られるため、フッ素含有排水中には硫酸イオンが含まれている。この硫酸イオン（ＳＯ４ ２−）は、フッ素含有排水にフッ素沈澱剤としてカルシウム化合物（例えばＣａＳＯ４）を添加してフッ化カルシウム（ＣａＦ２）の沈澱を生成させる方法において、フッ化カルシウムの沈澱形成を妨害してしまう。その妨害の理由は、硫酸イオンの存在下では、下記化学式１に示す反応が右側に進行し、フッ化物イオン（Ｆ−）の形成が促進されるためである。 In addition, when sulfurous acid gas in the exhaust gas is collected with a scrubber, sulfate ions are obtained, and therefore the fluorine-containing wastewater contains sulfate ions. This sulfate ion (SO 4 2− ) is produced by adding calcium compound (for example, CaSO 4 ) as a fluorine precipitating agent to fluorine-containing waste water to form calcium fluoride (CaF 2 ) precipitate. It will interfere with formation. The reason for the interference is that in the presence of sulfate ions, the reaction shown in the following chemical formula 1 proceeds to the right side and the formation of fluoride ions (F − ) is promoted.
ＣａＦ２＋ＳＯ４ ２−＝ＣａＳＯ４＋２Ｆ−・・・（化学式１） CaF 2 + SO 4 2− = CaSO 4 + 2F − (Chemical Formula 1)
これに対し本フッ素除去方法では、フッ素含有排水にリン酸を添加後、消石灰を添加してフッ素含有沈澱物を生成させることで、フッ素含有排水中の硫酸イオン濃度に影響を受けず、フッ素含有排水中のフッ素を安定して取り除くことができる。 In contrast, in this fluorine removal method, phosphoric acid is added to the fluorine-containing wastewater, and then slaked lime is added to produce a fluorine-containing precipitate, so that it is not affected by the sulfate ion concentration in the fluorine-containing wastewater. Fluorine in waste water can be removed stably.
また、マグネシウムは、フッ素含有排水にフッ素沈澱剤としてカルシウム化合物（例えばＣａＳＯ４）を添加してフッ化カルシウム（ＣａＦ２）の沈澱を生成させる方法において、硫酸イオンの存在時にフッ素の除去を妨害するという性質を有している。具体的には、フッ素含有排水中のマグネシウム及び硫酸イオンにより生成する硫酸マグネシウムによって、沈澱したフッ化カルシウムからのフッ素の再溶解が助長される。また、硫酸マグネシウム濃度の上昇に伴って排水中のフッ素濃度が上昇してフッ素の分離が不完全になる。そのため、特許文献１に記載のように、従来、マグネシウム濃度調整工程が必要であった。 Magnesium impedes the removal of fluorine in the presence of sulfate ions in a method in which a calcium compound (for example, CaSO 4 ) is added as a fluorine precipitating agent to fluorine-containing wastewater to form a precipitate of calcium fluoride (CaF 2 ). It has the property of Specifically, magnesium sulfate generated by magnesium and sulfate ions in the fluorine-containing wastewater promotes re-dissolution of fluorine from precipitated calcium fluoride. In addition, as the magnesium sulfate concentration increases, the fluorine concentration in the wastewater increases, resulting in incomplete fluorine separation. Therefore, as described in Patent Document 1, a magnesium concentration adjustment process has been conventionally required.
これに対し本フッ素除去方法では、フッ素含有排水にリン酸を添加後、消石灰を添加してフッ素含有沈澱物を生成させることで、フッ素含有排水中のマグネシウム濃度に影響を受けず、フッ素含有排水中のフッ素を安定して取り除くことができる。 In contrast, in this fluorine removal method, after adding phosphoric acid to fluorine-containing wastewater, slaked lime is added to produce a fluorine-containing precipitate, so that the fluorine-containing wastewater is not affected by the magnesium concentration in the fluorine-containing wastewater. The fluorine inside can be removed stably.
（１−２．各工程の概略）
本発明の一実施形態に係るフッ素除去方法は、図１に示すように、フッ素含有排水にリン酸を添加する工程（以下、「リン酸添加工程Ｓ１１」という。）の後に、フッ素含有排水中のフッ素を沈澱として分離除去する工程（以下、「フッ素沈澱除去工程Ｓ１２」という。）を行うものである。
(1-2. Outline of each process)
As shown in FIG. 1, the fluorine removal method according to one embodiment of the present invention is in the fluorine-containing wastewater after the step of adding phosphoric acid to the fluorine-containing wastewater (hereinafter referred to as “phosphoric acid addition step S11”). The step of separating and removing the fluorine as a precipitate (hereinafter referred to as “fluorine precipitation removing step S12”) is performed.
（１−３．リン酸添加工程）
図１に示すリン酸添加工程Ｓ１１では、リン酸をフッ素含有排水に添加する。ここで、フッ素含有排水は硫酸イオンを含むため、リン酸の添加前に消石灰をフッ素含有排水に添加、又はリン酸と消石灰を同時にフッ素含有排水に添加すると、硫酸イオンと消石灰が反応して硫酸カルシウムとして沈澱する。硫酸カルシウムの沈澱はスラッジとして処理されるため、沈澱の増加はスラッジ処理のコストアップとなり好ましくない。これに対し、本実施形態では消石灰の添加前にリン酸添加工程を行うことで、予めフッ素含有排水中にリン酸を添加する。これにより硫酸カルシウムを含むスラッジの生成を抑えることができ、低コストでフッ素を分離除去することができる。
(1-3. Phosphoric acid addition step)
In phosphoric acid addition process S11 shown in FIG. 1, phosphoric acid is added to fluorine-containing waste water. Here, since the fluorine-containing wastewater contains sulfate ions, if slaked lime is added to the fluorine-containing wastewater before the addition of phosphoric acid, or phosphoric acid and slaked lime are added to the fluorine-containing wastewater at the same time, the sulfate ions react with the slaked lime. Precipitate as calcium. Since precipitation of calcium sulfate is treated as sludge, an increase in precipitation is not preferable because it increases the cost of sludge treatment. On the other hand, in this embodiment, phosphoric acid is added in advance to the fluorine-containing wastewater by performing a phosphoric acid addition step before the addition of slaked lime. Thereby, generation of sludge containing calcium sulfate can be suppressed, and fluorine can be separated and removed at low cost.
また、リン酸添加工程を行わず、消石灰をフッ素含有排水に添加してフッ化カルシウムを沈澱させた場合、上述したように硫酸カルシウムのスラッジが生成するため処理コストの点で好ましくない。本実施形態では消石灰の添加前にリン酸添加工程を行うことで、硫酸カルシウムを含むスラッジの生成を抑えることができ、低コストでフッ素を分離除去することができる。 In addition, when calcium fluoride is precipitated by adding slaked lime to fluorine-containing wastewater without performing the phosphoric acid addition step, calcium sulfate sludge is generated as described above, which is not preferable in terms of processing costs. In this embodiment, by performing the phosphoric acid addition step before the addition of slaked lime, generation of sludge containing calcium sulfate can be suppressed, and fluorine can be separated and removed at low cost.
リン酸の添加量は、フッ素含有排水中の総フッ素量に対しリン酸中のリンの量が０．２倍以上５．０倍以下の物質量（モル量）となるよう調整するのが望ましく、０．２倍以上３．０倍以下の物質量（モル量）となるよう調整するのがさらに望ましい。リン酸中のリンの量がフッ素含有排水中の総フッ素量の０．２倍未満では、十分にフッ素を除去することができなくなってしまう。リン酸中のリンの量がフッ素含有排水中の総フッ素量の５．０倍を超えると、リン酸の添加量を増やしても生成する澱物量が大きくなり澱物廃棄のコストが大きくなってしまう。リン酸の添加量を、リン酸中のリンの量がフッ素含有排水中の総フッ素量の０．２倍以上５．０倍以下となるよう調整することで、リン酸のコストを抑えつつ、フッ素の沈澱量を増加することができる。 The addition amount of phosphoric acid is preferably adjusted so that the amount of phosphorus in phosphoric acid is 0.2 to 5.0 times the amount of substance (molar amount) with respect to the total fluorine amount in fluorine-containing wastewater. It is more desirable to adjust the substance amount (molar amount) to be 0.2 times or more and 3.0 times or less. If the amount of phosphorus in phosphoric acid is less than 0.2 times the total amount of fluorine in the fluorine-containing wastewater, fluorine cannot be removed sufficiently. If the amount of phosphorus in phosphoric acid exceeds 5.0 times the total fluorine content in fluorine-containing wastewater, the amount of starch produced will increase even if the amount of phosphoric acid added is increased, and the cost of starch disposal will increase. End up. By adjusting the amount of phosphoric acid added so that the amount of phosphorus in phosphoric acid is 0.2 to 5.0 times the total fluorine amount in the fluorine-containing wastewater, while suppressing the cost of phosphoric acid, Fluorine precipitation can be increased.
（１−４．フッ素沈澱除去工程）
図１に示すフッ素沈澱除去工程Ｓ１２では、リン酸添加工程Ｓ１１後のフッ素含有排水に消石灰を添加してフッ素を除去する。フッ素沈澱除去工程Ｓ１２では、リン酸添加工程Ｓ１１後のフッ素含有排水に消石灰を添加してフッ素含有沈澱物を生成させる。その後、固液分離によりフッ素除去排水及びフッ素含有沈澱物を分離する。
(1-4. Fluorine Precipitation Removal Step)
In the fluorine precipitation removal step S12 shown in FIG. 1, slaked lime is added to the fluorine-containing wastewater after the phosphoric acid addition step S11 to remove fluorine. In the fluorine precipitation removing step S12, slaked lime is added to the fluorine-containing wastewater after the phosphoric acid addition step S11 to generate a fluorine-containing precipitate. Thereafter, the fluorine-removed waste water and the fluorine-containing precipitate are separated by solid-liquid separation.
フッ素沈澱除去工程Ｓ１２では、フッ素含有排水中のフッ素を、フッ化アパタイトの生成により除去していると考えられる。具体的には、リン酸添加工程Ｓ１１で添加したリン酸と、フッ素沈澱除去工程Ｓ１２で添加する消石灰により、下記化学式２に示す反応が右側に進行し、フッ化アパタイト（Ｃａ５（ＰＯ４）３Ｆ）が生成し、フッ素が共沈すると考えられる。なお、フッ素含有沈澱物にはフッ化アパタイトのみでなく、例えばＭｇＦ２等も含有される。 In the fluorine precipitation removing step S12, it is considered that the fluorine in the fluorine-containing waste water is removed by the production of fluorinated apatite. Specifically, the reaction shown in the following chemical formula 2 proceeds to the right side by the phosphoric acid added in the phosphoric acid addition step S11 and the slaked lime added in the fluorine precipitation removal step S12, and fluorinated apatite (Ca 5 (PO 4 )). 3 F) is produced and fluorine is co-precipitated. Note that the fluorine-containing precipitate contains not only fluorinated apatite but also MgF 2 , for example.
３Ｈ３ＰＯ４＋５Ｃａ（ＯＨ）２＋Ｆ−→Ｃａ５（ＰＯ４）３Ｆ＋９Ｈ２Ｏ＋ＯＨ−・・・・（化学式２） 3H 3 PO 4 + 5Ca (OH) 2 + F − → Ca 5 (PO 4 ) 3 F + 9H 2 O + OH − (Chemical Formula 2)
ここで、化学式２に示すフッ化アパタイト（Ｃａ５（ＰＯ４）３Ｆ）の生成反応は、化学式１に示すフッ化カルシウムの生成反応と異なり、硫酸イオンの濃度に依存しない。このため、本発明の一実施の形態に係るフッ素沈澱除去工程では、フッ素含有排水中の硫酸イオン濃度に影響を受けず、フッ素含有排水中のフッ素を安定して取り除くことができると考えられる。 Here, the formation reaction of fluorinated apatite (Ca 5 (PO 4 ) 3 F) represented by Chemical Formula 2 does not depend on the concentration of sulfate ions, unlike the formation reaction of calcium fluoride represented by Chemical Formula 1. For this reason, in the fluorine precipitation removal process which concerns on one embodiment of this invention, it is thought that it is not influenced by the sulfate ion concentration in fluorine-containing wastewater, and can remove fluorine in fluorine-containing wastewater stably.
また、フッ化アパタイトの溶解度は石膏などの硫酸化合物の溶解度よりも小さく、そして、フッ化アパタイトは石膏などの硫酸化合物よりも安定である。このため、フッ素含有排水中のマグネシウム及び硫酸イオンによって、フッ化アパタイト沈澱物からフッ素が再溶解してフッ素含有排水中のフッ素濃度が上昇することは考えにくい。このため、本発明の一実施の形態に係るフッ素沈澱除去工程では、フッ素含有排水中のマグネシウムイオン濃度に影響を受けず、フッ素含有排水中のフッ素を安定して取り除くことができると考えられる。 Further, the solubility of fluorapatite is smaller than the solubility of sulfate compounds such as gypsum, and fluorapatite is more stable than sulfate compounds such as gypsum. For this reason, it is unlikely that the fluorine concentration in the fluorine-containing wastewater increases due to the redissolution of fluorine from the fluorinated apatite precipitate due to magnesium and sulfate ions in the fluorine-containing wastewater. For this reason, in the fluorine precipitation removal process which concerns on one embodiment of this invention, it is thought that it is not influenced by the magnesium ion concentration in fluorine-containing wastewater, and can remove fluorine in fluorine-containing wastewater stably.
フッ素沈澱除去工程Ｓ１２において、消石灰の添加量を、フッ素含有排水中のリンに対する、消石灰中のカルシウムのモル比（以下「Ｃａ／Ｐ」という）が、１．６７となるよう調整することが好ましい。フッ化アパタイトはＣａ５（ＰＯ４）３Ｆで表されＣａ／Ｐ＝５／３≒１．６７である。Ｃａ／Ｐモル比が２.００より大きくなると、澱物が不安定となりフッ素の除去効果が小さくなるため好ましくない。一方、Ｃａ／Ｐモル比が１．６７より小さくなると排水中のリン濃度が高まり環境に悪影響を及ぼすため好ましくない。 In the fluorine precipitation removing step S12, the amount of slaked lime added is preferably adjusted so that the molar ratio of calcium in slaked lime to phosphorus in the fluorine-containing wastewater (hereinafter referred to as “Ca / P”) is 1.67. . The fluorapatite is expressed by Ca 5 (PO 4 ) 3 F, and Ca / P = 5 / 3≈1.67. When the Ca / P molar ratio is larger than 2.00, the starch becomes unstable and the effect of removing fluorine becomes small, which is not preferable. On the other hand, if the Ca / P molar ratio is smaller than 1.67, the phosphorus concentration in the wastewater is increased, which is not preferable because it adversely affects the environment.
フッ素沈澱除去工程Ｓ１２では、消石灰を添加したフッ素含有排水に、濾過処理を施してフッ素を分離除去し、フッ素除去排水が得られる。このフッ素除去排水は、引き続いて排水処理施設に送られ、一般の排水と共に中和や酸化還元等の方法によって、重金属や有機物等を分離し、無害化された後に排出される。 In the fluorine precipitation removing step S12, the fluorine-containing wastewater to which slaked lime is added is subjected to a filtration treatment to separate and remove fluorine, thereby obtaining a fluorine-removed wastewater. This fluorine-removed wastewater is subsequently sent to a wastewater treatment facility, and together with general wastewater, heavy metals, organic substances, and the like are separated and made harmless by methods such as neutralization and oxidation / reduction, and then discharged.
以下に示す実施例及び比較例によって本発明を更に詳細に説明するが、本発明は、これらの実施例及び比較例によって何ら限定されるものではない。 The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples and comparative examples.
（実施例１）
実施例１では、フッ素濃度８００ｍｇ／Ｌ、硫酸３０ｇ／Ｌ、マグネシウム５ｇ／Ｌである非鉄金属製錬工程の排水（始液）を１００ｍＬのビーカーに入れ、リン酸を０．５９ｇ添加した。次に、前記リン酸を添加したフッ素含有排水のビーカーに、Ｃａ／Ｐモル比が１．６７となるよう、粉末状の消石灰を０．７４ｇ添加し、スターラーで１時間撹拌し、固液分離した。フッ素濃度は、蒸留分離吸光光度法を用いて分析した。ろ液（フッ素除去排水）のフッ素濃度は９１ｍｇ／Ｌであり、始液のフッ素を十分に除去することができた。
Example 1
In Example 1, the non-ferrous metal smelting process wastewater (starting liquid) having a fluorine concentration of 800 mg / L, sulfuric acid of 30 g / L, and magnesium of 5 g / L was placed in a 100 mL beaker, and 0.59 g of phosphoric acid was added. Next, 0.74 g of powdered slaked lime is added to the beaker of the fluorine-containing wastewater to which the phosphoric acid has been added so that the Ca / P molar ratio is 1.67, and the mixture is stirred for 1 hour with a stirrer and solid-liquid separated did. The fluorine concentration was analyzed using distillation separation spectrophotometry. The fluorine concentration of the filtrate (fluorine-removed waste water) was 91 mg / L, and the fluorine in the starting liquid could be sufficiently removed.
（実施例２）
実施例２では、消石灰添加量を０．８８ｇとした以外は、実施例１と同様の処理を行った。ろ液のフッ素濃度は１００ｍｇ／Ｌであり、始液のフッ素を十分に除去することができた。
(Example 2)
In Example 2, the process similar to Example 1 was performed except the amount of slaked lime addition having been 0.88g. The fluorine concentration in the filtrate was 100 mg / L, and the fluorine in the starting solution could be removed sufficiently.
（比較例１）
比較例１では、消石灰添加量を１．１ｇとした以外は、実施例１と同様の処理を行った。ろ液のフッ素濃度は１８０ｍｇ／Ｌであり、始液のフッ素を十分に除去することができなかった。
(Comparative Example 1)
In Comparative Example 1, the same treatment as in Example 1 was performed except that the amount of slaked lime added was 1.1 g. The fluorine concentration of the filtrate was 180 mg / L, and the fluorine in the starting solution could not be removed sufficiently.
（比較例２）
比較例２では、リン酸添加を省いた以外は、実施例１と同様の処理を行った。ろ液のフッ素量は３３０ｍｇ／Ｌであり、始液のフッ素を十分に除去することができなかった。
(Comparative Example 2)
In Comparative Example 2, the same treatment as in Example 1 was performed except that phosphoric acid addition was omitted. The amount of fluorine in the filtrate was 330 mg / L, and the fluorine in the starting solution could not be removed sufficiently.
以下の表１に、ろ液のフッ素濃度の分析結果を示す。 Table 1 below shows the analysis results of the fluorine concentration of the filtrate.
表１に示す結果から、実施例１では、固液分離により得られたろ液（フッ素除去排水）のフッ素濃度は９１ｍｇ／Ｌ、実施例２では１００ｍｇ／Ｌと、始液のフッ素濃度を低減することができた。 From the results shown in Table 1, in Example 1, the fluorine concentration of the filtrate (fluorine removal wastewater) obtained by solid-liquid separation is 91 mg / L, and in Example 2, the fluorine concentration of the starting liquid is reduced to 100 mg / L. I was able to.
一方、比較例１では、消石灰添加量を１．１ｇとした以外は、実施例１と同様の処理を行った。その結果、比較例１では、固液分離により得られたろ液のフッ素濃度は１８０ｍｇ／Ｌと、始液のフッ素濃度を十分に低減することが出来なかった。これは、消石灰の添加量のＣａ／Ｐモル比が、２．５と増加したため、澱物が不安定となりフッ素の除去効果が小さくなるためと考えられる。 On the other hand, in the comparative example 1, the process similar to Example 1 was performed except the slaked lime addition amount having been 1.1 g. As a result, in Comparative Example 1, the fluorine concentration of the filtrate obtained by solid-liquid separation was 180 mg / L, and the fluorine concentration of the starting liquid could not be sufficiently reduced. This is probably because the Ca / P molar ratio of the added amount of slaked lime increased to 2.5, so that the starch became unstable and the effect of removing fluorine was reduced.
一方、比較例２では、リン酸添加を省いた以外は、実施例１と同様の処理を行った。その結果、比較例２では、固液分離により得られたろ液のフッ素濃度は、３３０ｍｇ／Ｌであり、始液のフッ素を十分に除去することができなかった。これは、硫酸イオンが存在するために、フッ化カルシウムの沈澱形成を妨害されてしまうためと考えられる。 On the other hand, in Comparative Example 2, the same treatment as in Example 1 was performed except that phosphoric acid addition was omitted. As a result, in Comparative Example 2, the fluorine concentration of the filtrate obtained by solid-liquid separation was 330 mg / L, and the fluorine in the starting liquid could not be sufficiently removed. This is presumably because the presence of sulfate ions hinders the formation of calcium fluoride precipitates.
以上の結果から、硫酸イオンとマグネシウムを含むフッ素含有排水に対して、リン酸と消石灰の添加により、フッ素含有排水から簡単且つ低コストで効率よくフッ素を分離除去することができ、しかも硫酸イオン濃度を調整することなく、常に安定して確実にフッ素を分離除去することができることがわかる。 From the above results, fluorine can be easily separated and removed from fluorine-containing wastewater efficiently and at low cost by adding phosphoric acid and slaked lime to fluorine-containing wastewater containing sulfate ions and magnesium. It can be seen that fluorine can always be separated and removed stably and reliably without adjusting.
なお、上記のように本発明の各実施形態及び各実施例について詳細に説明したが、本発明の新規事項及び効果から実体的に逸脱しない多くの変形が可能であることは、当業者には、容易に理解できるであろう。従って、このような変形例は、全て本発明の範囲に含まれるものとする。 Although the embodiments and examples of the present invention have been described in detail as described above, it will be understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. It will be easy to understand. Therefore, all such modifications are included in the scope of the present invention.
例えば、明細書又は図面において、少なくとも一度、より広義又は同義な異なる用語と共に記載された用語は、明細書又は図面のいかなる箇所においても、その異なる用語に置き換えることができる。また、フッ素除去方法の構成、動作も本発明の各実施形態及び各実施例で説明したものに限定されず、種々の変形実施が可能である。 For example, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. The configuration and operation of the fluorine removal method are not limited to those described in the embodiments and examples of the present invention, and various modifications can be made.
Ｓ１１ リン酸添加工程、Ｓ１２ フッ素沈澱除去工程 S11 Phosphoric acid addition process, S12 Fluorine precipitation removal process
Claims (4)
前記フッ素含有排水にリン酸を添加するリン酸添加工程と、
前記リン酸添加工程後のフッ素含有排水に消石灰を添加して、生成したフッ素含有沈澱物を分離除去するフッ素沈澱除去工程とを有することを特徴とするフッ素除去方法。 A method for removing fluorine from fluorine-containing wastewater containing sulfate ions and magnesium produced from a non-ferrous metal smelting process,
A phosphoric acid addition step of adding phosphoric acid to the fluorine-containing waste water;
A fluorine removal method comprising: adding a slaked lime to the fluorine-containing wastewater after the phosphoric acid addition step to separate and remove the generated fluorine-containing precipitate.
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| JP7388949B2 (en) | 2020-02-28 | 2023-11-29 | 太平洋セメント株式会社 | Waste liquid treatment method |
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