JP2011016120A - Removing agent of fluorine ion in wastewater and fluorine ion removing method using the same - Google Patents
Removing agent of fluorine ion in wastewater and fluorine ion removing method using the same Download PDFInfo
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- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 title claims abstract description 54
- 239000002351 wastewater Substances 0.000 title claims abstract description 54
- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims description 21
- 239000011737 fluorine Substances 0.000 claims abstract description 51
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 51
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 51
- 229910000514 dolomite Inorganic materials 0.000 claims abstract description 44
- 239000010459 dolomite Substances 0.000 claims abstract description 44
- -1 fluorine ions Chemical class 0.000 claims abstract description 44
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 37
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000000292 calcium oxide Substances 0.000 claims abstract description 27
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 24
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 17
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 8
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 8
- 235000011116 calcium hydroxide Nutrition 0.000 claims abstract description 8
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims description 14
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 230000002378 acidificating effect Effects 0.000 claims description 5
- 239000008187 granular material Substances 0.000 claims description 4
- 238000001354 calcination Methods 0.000 claims description 3
- 238000012423 maintenance Methods 0.000 claims description 3
- 235000010575 Pueraria lobata Nutrition 0.000 claims description 2
- 244000046146 Pueraria lobata Species 0.000 claims description 2
- 238000002347 injection Methods 0.000 claims description 2
- 239000007924 injection Substances 0.000 claims description 2
- 230000007613 environmental effect Effects 0.000 abstract description 7
- 238000004065 wastewater treatment Methods 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 3
- 235000012255 calcium oxide Nutrition 0.000 description 24
- 238000010304 firing Methods 0.000 description 13
- 239000007788 liquid Substances 0.000 description 13
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 8
- 239000004480 active ingredient Substances 0.000 description 6
- 238000006114 decarboxylation reaction Methods 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 5
- 235000011941 Tilia x europaea Nutrition 0.000 description 5
- 239000004571 lime Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 4
- 229910001634 calcium fluoride Inorganic materials 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 4
- 239000011775 sodium fluoride Substances 0.000 description 4
- 235000013024 sodium fluoride Nutrition 0.000 description 4
- 239000011575 calcium Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 159000000007 calcium salts Chemical class 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000002516 radical scavenger Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000007655 standard test method Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
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- Water Treatment By Sorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
Description
本発明は、半焼成ドロマイトを有効成分とし、フッ素イオンを含有する排水中のフッ素イオンを除去するための除去剤と、それを使用したフッ素イオンの除去方法に関する。本発明において「半焼成ドロマイト」とは、ドロマイト鉱石を６００〜９００℃の温度で焼成することにより、ドロマイト成分中の炭酸マグネシウムの大部分を脱炭酸させて酸化マグネシウムとする一方、炭酸カルシウムはほとんど脱炭酸させず、そのまま残すようにして得た焼成品を指す。 The present invention relates to a remover for removing fluorine ions in wastewater containing fluorine ions containing semi-baked dolomite as an active ingredient, and a fluorine ion removal method using the same. In the present invention, “semi-calcined dolomite” means calcining dolomite ore at a temperature of 600 to 900 ° C. to decarboxylate most of the magnesium carbonate in the dolomite component to make magnesium oxide, while calcium carbonate is mostly It refers to a fired product obtained by leaving it as it is without decarboxylation.
たとえば半導体の製造工場においては、その製造工程においてフッ酸を使用するため、どうしてもフッ素イオンを含有する排水が多量に排出される。この排水からフッ素イオンを除去し、無害化するためにとられている基本的な対策は、排水に水溶性のカルシウム塩を添加してフッ化カルシウムを生成させることによりフッ素イオンを不溶化し、分離することである。このとき生成するフッ化カルシウムの沈殿は、微細な粒子であるから、その分離を容易にするため、塩化第二鉄やポリ塩化アルミニウム（ＰＡＣ）のような無機凝集剤を添加するか、高分子凝集剤を添加してフッ化カルシウム凝集フロックを生成させ、生成したフロックを沈殿槽で沈殿させることが行なわれている。 For example, in a semiconductor manufacturing factory, since hydrofluoric acid is used in the manufacturing process, a large amount of waste water containing fluorine ions is inevitably discharged. The basic measures taken to remove and detoxify fluorine ions from this wastewater are to make the fluoride ions insoluble by adding water-soluble calcium salt to the wastewater to produce calcium fluoride. It is to be. The precipitates of calcium fluoride produced at this time are fine particles, so an inorganic flocculant such as ferric chloride or polyaluminum chloride (PAC) is added or polymer is added to facilitate the separation. A flocculant is added to produce calcium fluoride aggregated floc, and the generated floc is precipitated in a precipitation tank.
しかし、フッ化カルシウムの溶解度は比較的高く、単にカルシウム塩で処理しただけでは、排水中のフッ素イオンの濃度を、排水基準値である８mg／Ｌ以下にすることは困難である。そこで酸化マグネシウム系の化合物を使用するフッ素含有排水の処理方法が提案された（特許文献１）。その処理方法は、ＢＥＴ比表面積が１０ｍ2／ｇ以上で粒度が１０μm〜１０mmに調製した酸化マグネシウムをフッ素吸着剤として使用し、主としてこれをカラムに充填して通水するものである。 However, the solubility of calcium fluoride is relatively high, and it is difficult to reduce the fluorine ion concentration in the wastewater to 8 mg / L or less, which is the wastewater standard value, simply by treating with calcium salt. Then, the processing method of the fluorine-containing waste water which uses a magnesium oxide type compound was proposed (patent document 1). The treatment method uses magnesium oxide prepared with a BET specific surface area of 10 m 2 / g or more and a particle size of 10 μm to 10 mm as a fluorine adsorbent, which is mainly packed in a column and passed through.
酸化マグネシウムを利用して排水中のフッ素イオンを吸着除去する別の方法は、水酸化マグネシウムを７００〜１０００℃で焼成してＢＥＴ表面積４０〜２００ｍ2／ｇとした酸化マグネシウムを、フッ素イオンを含有するｐＨ４．０以下の排水に添加し、１０〜２５℃の温度で処理したのち、凝集剤を加えて固液分離することからなる（特許文献２）。 Another method for adsorbing and removing fluorine ions in wastewater using magnesium oxide is to fluorinate magnesium oxide by baking magnesium hydroxide at 700 to 1000 ° C. to a BET surface area of 40 to 200 m 2 / g, containing fluorine ions. It is added to wastewater having a pH of 4.0 or less, treated at a temperature of 10 to 25 ° C., and then solid-liquid separated by adding a flocculant (Patent Document 2).
フッ素イオン除去の性能を有する生石灰と酸化マグネシウムとを有利に併用することを意図して、焼成ドロマイトを使用する「フッ化物イオン捕捉材」が提案された（特許文献３）。この捕捉材は、「中程度の分解率のドロマイト」であって、温度６００〜８８０℃で焼成した、ＭｇＯ、ＣａＯおよびＣａＣＯ３を主要構成物とし、未分解二酸化炭素が１．５〜４７重量％であるものと規定され、排水に残留するフッ素イオン濃度を低減するためにも、またフッ素で汚染された土壌からの溶出量を低減するにも用いることができる。
発明者らは、このドロマイトを焼成してＭｇＯ、ＣａＯおよびＣａＣＯ３を主要構成成分としたものを排水中のフッ素イオンを除去するために使用する技術を深く研究し、排水基準値である８．０mg／Ｌを満たすとともに、水質汚濁に係る環境基準値である０．８mg／Ｌを確実に達成することを可能にする除去剤の限定としては、未分解二酸化炭素が１．５〜４７重量％の焼成ドロマイトというような、おおざっぱな限定では不完全であって、よりきめ細かく性状を限定する必要があることを経験した。限定すべき事項として発明者が見出したのは、半焼成ドロマイト中の遊離酸化カルシウムの量と遊離酸化マグネシウムの量とである。 The inventors have deeply researched a technique for firing this dolomite and using MgO, CaO, and CaCO 3 as main constituents to remove fluorine ions in the wastewater, which is the wastewater standard value. As a limitation of the removal agent that satisfies 0 mg / L and can reliably achieve the environmental standard value of 0.8 mg / L related to water pollution, undecomposed carbon dioxide is 1.5 to 47% by weight. I have experienced that the rough limitation, such as baked dolomite, is incomplete and the properties need to be more finely defined. What the inventors have found as matters to be limited are the amount of free calcium oxide and the amount of free magnesium oxide in the semi-baked dolomite.
本発明の目的は、上記した発明者らが得た知見を活用し、排水中のフッ素イオンを除去して環境基準値を満たすものとする上で確実な効果が得られるような半焼成ドロマイトからなるフッ素イオン除去剤を提供し、それによって効果的な排水処理の方法を実現することにある。 The purpose of the present invention is to make use of the knowledge obtained by the above-described inventors, from a semi-calcined dolomite that provides a certain effect in satisfying the environmental standard value by removing fluorine ions in the waste water. It is to provide a fluorine ion removing agent, thereby realizing an effective wastewater treatment method.
本発明に従う排水中のフッ素イオンの除去剤は、ドロマイトを焼成して得られ、遊離の酸化カルシウムの含有量が１．５重量％以下、好ましくは１．２重量％以下であって、遊離の酸化マグネシウムの含有量が７重量％、好ましくは１９重量％以上である半焼成ドロマイトを有効成分とする除去剤である。 The fluorine ion removing agent in the waste water according to the present invention is obtained by firing dolomite, and the content of free calcium oxide is 1.5% by weight or less, preferably 1.2% by weight or less. It is a remover containing semi-calcined dolomite having a magnesium oxide content of 7% by weight, preferably 19% by weight or more as an active ingredient.
本発明に従う排水中のフッ素イオンを除去する方法の基本的態様は、上記した半焼成ドロマイトを有効成分とするフッ素イオンの除去剤を、フッ素を含有する酸性の排水に接触させ、排水中のフッ素を除去することからなる。 The basic aspect of the method for removing fluorine ions in waste water according to the present invention is to bring a fluorine ion remover containing semi-calcined dolomite as an active ingredient into contact with acidic waste water containing fluorine, and It consists of removing.
本発明に従う排水中のフッ素イオンを除去する方法の変更態様は、フッ素を含有する酸性の排水に、まず消石灰を接触させてフッ素イオンの一部を除去し、フッ素イオンの濃度が低下したがなお環境基準値を満たすに至っていない排水に、本発明の半焼成ドロマイトを有効成分とする除去剤を接触させ、排水中のフッ素をさらに除去することからなる。 In the modified embodiment of the method for removing fluorine ions in the waste water according to the present invention, the slaked lime is first brought into contact with acidic waste water containing fluorine to remove a part of the fluorine ions, and the concentration of fluorine ions is reduced. The waste water that does not satisfy the environmental standard value is brought into contact with a removing agent containing the semi-baked dolomite of the present invention as an active ingredient, and fluorine in the waste water is further removed.
本発明のフッ素イオンの除去剤は、ドロマイトの半焼成により得られ、高いフッ素イオン吸着除去性能を示し、しかも排水と接触している間に崩壊し難いから、この除去材を固定床に充填し、それに排水を接触させることにより排水の処理をすることが可能である。 The fluorine ion remover of the present invention is obtained by semi-firing dolomite, exhibits high fluorine ion adsorption removal performance, and is difficult to disintegrate while in contact with waste water. It is possible to treat the waste water by bringing it into contact with the waste water.
本発明の方法により半焼成ドロマイトを有効成分とするフッ素イオン除去剤を使用して排水処理を行なえば、上記した基本的態様であれ、変更態様であれ、排水中のフッ素イオンを効果的に除去することができるから、その濃度を排水基準値である８．０mg／Ｌ以下に低減することが容易である。 If wastewater treatment is performed using a fluorine ion removing agent containing semi-baked dolomite as an active ingredient according to the method of the present invention, fluorine ions in the wastewater are effectively removed regardless of whether the basic mode or the modified mode described above. Therefore, it is easy to reduce the concentration to 8.0 mg / L or less which is the drainage standard value.
本発明の半焼成ドロマイト中に含まれる「遊離酸化カルシウム」の含有量は、日本石灰協会の「日本石灰協会標準試験方法（２００６）」に規定の「１１．有効石灰の定量方法」に従って分析される、ＣａＯおよびＣａ（ＯＨ）２を合計した量（重量％）である。一方、「遊離酸化マグネシウム」の含有量とは、ドロマイト中のＭｇＣＯ３が脱炭酸して生成したＭｇＯの量として算出される量をいう。その算出は、つぎの手順に従って行なう。
・まず、ＪＩＳ Ｒ９０１１の「石灰の分析方法」に規定された方法により、ＣａＯ，ＭｇＯおよびIg.loss（灼熱減量）を分析する。つぎに、分析によって得た遊離酸化カルシウムの量が１．５％に達しているか否かによって、下記のいずれかを選ぶ。
・遊離酸化カルシウムの量が１．５％以上のとき：分析で得たＭｇＯの値を、そのまま遊離酸化マグネシウムの量として採用する。
・遊離酸化カルシウムの量が１．５％未満のとき：遊離酸化マグネシウムの量は、分析で得たＭｇＯ％−ＭｇＣＯ３として存在するＭｇＯ％により算出する。ＭｇＣＯ３として存在するＭｇＯ％は、
｛Ig.loss％−（ＣａＯ％÷５６×４４）｝÷４４×４０
により求める。
The content of “free calcium oxide” contained in the semi-baked dolomite of the present invention is analyzed in accordance with “11. Method for Quantifying Effective Lime” defined in “Japan Lime Association Standard Test Method (2006)” of the Japan Lime Association. The total amount (% by weight) of CaO and Ca (OH) 2 . On the other hand, the content of “free magnesium oxide” refers to an amount calculated as the amount of MgO produced by decarboxylation of MgCO 3 in dolomite. The calculation is performed according to the following procedure.
First, CaO, MgO and Ig.loss (loss on ignition) are analyzed by the method defined in “Analyzing Method of Lime” in JIS R9011. Next, one of the following is selected depending on whether or not the amount of free calcium oxide obtained by analysis has reached 1.5%.
-When the amount of free calcium oxide is 1.5% or more: The value of MgO obtained by analysis is directly adopted as the amount of free magnesium oxide.
- when the amount of free calcium oxide is less than 1.5%: the amount of free magnesium oxide is calculated by MgO% present as MgO% MgCO 3 was obtained in the analysis. MgO% present as MgCO 3 is
{Ig.loss%-(CaO% ÷ 56 × 44)} ÷ 44 × 40
Ask for.
排水中のフッ素イオンを高度に除去するためには、遊離酸化カルシウムの含有量が低いことが望ましい。したがって、ドロマイトの半焼成に当たり、ＣａＣＯ３の脱炭酸はできるだけ抑制することが望ましい。その理由は、つぎのように説明される。すなわち、ＭｇＯによるフッ素イオン除去の反応機構は、
Ｍｇ２＋＋Ｆ−＋ＯＨ−＝［Ｍｇ（ＯＨ）２］Ｆ
と考えられるところ、Ｆ−との反応はＭｇＯよりもＣａＯの方が速いため、遊離酸化カルシウムの量が多いと、Ｆ−がＣａＯと反応して安定なＣａＦ２を形成し、それが除去剤の表面を覆ってしまい、ＭｇＯとの反応が妨げられる。その一方で、ＣａＦの溶解度は比較的高いから、溶液中のフッ素イオン濃度は、排水基準値以下にすることに困難がある。液性に関して見れば、フッ素イオンの除去にはｐＨが低い方が有利であるところ、ＣａＯが多量に存在するとｐＨが高くなって、不利に作用する。このようなわけで、遊離酸化カルシウム量は１．５重量％以下であることが必要であり、１．２重量％以下であることが好ましい。
In order to highly remove fluorine ions in the wastewater, it is desirable that the content of free calcium oxide is low. Therefore, it is desirable to suppress the decarboxylation of CaCO 3 as much as possible during the semi-firing of dolomite. The reason is explained as follows. That is, the reaction mechanism of fluorine ion removal by MgO is
Mg 2+ + F − + OH − = [Mg (OH) 2 ] F
Therefore, since the reaction with F − is faster in CaO than in MgO, when the amount of free calcium oxide is large, F − reacts with CaO to form stable CaF 2 , which is a remover. The reaction with MgO is hindered. On the other hand, since the solubility of CaF is relatively high, it is difficult to make the fluorine ion concentration in the solution below the drainage standard value. From the viewpoint of liquidity, a lower pH is advantageous for removing fluorine ions. However, if CaO is present in a large amount, the pH becomes higher and acts adversely. For this reason, the amount of free calcium oxide needs to be 1.5% by weight or less, and preferably 1.2% by weight or less.
遊離酸化マグネシウムは、フッ素イオン除去のための有効成分であるから、多量に含まれていることが必要であって、この含有量が低いと、同じ量のフッ素イオンを除去するのに、多量の半焼成ドロマイトを消費しなければならない。不相当に多量の半焼成ドロマイトを消費しないでフッ素イオンの除去を行なうには、半焼成ドロマイトが、少なくとも７重量％の遊離酸化マグネシウムを含有することが必要である。後記する実施例にみるとおり、遊離酸化マグネシウムの含有量は１９重量％以上あることが好ましい。原理的にいえば、遊離酸化マグネシウムの含有量は高いほど有利なわけであるが、その値を高めようとしてドロマイトの焼成を過度に進めると、製品の半焼成ドロマイト中の遊離酸化カルシウムの量が増大してしまい、フッ素イオン除去剤としての性能が、かえって低下する。実用上の遊離酸化マグネシウム量は、２０重量％を若干上回る程度、多くとも２５重量％が上限となる。 Since free magnesium oxide is an active ingredient for removing fluorine ions, it needs to be contained in a large amount. If this content is low, a large amount of fluorine ions can be removed to remove the same amount of fluorine ions. Semi-baked dolomite must be consumed. In order to remove fluorine ions without consuming a relatively large amount of semi-calcined dolomite, the semi-calcined dolomite needs to contain at least 7% by weight of free magnesium oxide. As seen in the examples described later, the content of free magnesium oxide is preferably 19% by weight or more. In principle, the higher the free magnesium oxide content, the more advantageous. However, excessive calcination of the dolomite to increase its value will reduce the amount of free calcium oxide in the semi-baked dolomite of the product. It increases, and the performance as a fluorine ion removing agent is rather lowered. The practical amount of free magnesium oxide is slightly higher than 20% by weight, and at most 25% by weight is the upper limit.
上述のような、排水中のフッ素イオン除去剤として有用な半焼成ドロマイト、すなわち、ＭｇＣＯ３の脱炭酸は十分に行なうが、その一方でＣａＣＯ３の脱炭酸はなるべく抑制した半焼成ドロマイトを得るには、ドロマイトの焼成条件の選択が肝要になる。周知のとおり、ドロマイト鉱石の性状は産地によって変動するので、それぞれの場合に最適な焼成条件は実験的に決定するほかないが、通常は、焼成温度は６００〜９００℃、時間は１〜４８時間の範囲内に見出されるであろう。栃木県葛生産のドロマイトを例にとれば、温度７００〜８００℃、時間２〜２４時間の焼成が適切である。 As described above, useful semi-sintered dolomite as a fluorine ion removal agent in waste water, i.e., the decarboxylation of MgCO 3 is sufficiently performed, but decarboxylation while CaCO 3 get half burnt dolomite was possible inhibition Therefore, selection of the dolomite firing conditions is essential. As is well known, since the properties of dolomite ore vary depending on the place of production, the optimum firing conditions in each case must be determined experimentally. Usually, the firing temperature is 600 to 900 ° C., and the time is 1 to 48 hours. Will be found within the scope of Taking dolomite produced in Tochigi Prefecture Kuzu as an example, baking at a temperature of 700 to 800 ° C. for 2 to 24 hours is appropriate.
ドロマイトの焼成温度および時間は、焼成の条件によって異なる。たとえば、ＣａＣＯ３の脱炭酸を防ぐ目的で、ドロマイトをＣＯ２雰囲気下で焼成する試みが報告されており（Journal of Solid Chemistry 33, 181, 1980）、ＣＯ２雰囲気下や加圧下の焼成であれば、焼成温度は当然に高くなる。熱力学的にいっても、このような条件下では炭酸塩の分解温度が、大気雰囲気の場合よりも高くなるからである。それと反対に、アルカリ土類金属の水酸化物、代表的にはＣａ（ＯＨ）２の焼成を減圧下に行なうことによって、その分解温度を低くする技術がある（特開２００４−３５４４１４、特開２００６−２１９４５）。炭酸塩に関しても同様で、減圧下に焼成すれば、分解温度を低下させることができる。このように、ドロマイトの焼成の結果は、焼成条件によって異なるが、要は、遊離酸化カルシウムおよび遊離酸化マグネシウムの量が、前記した範囲に入るような焼成を行なうことである。 The firing temperature and time of dolomite vary depending on the firing conditions. For example, there in order to prevent decarboxylation of CaCO 3, dolomite CO 2 is attempting to firing is reported in an atmosphere (Journal of Solid Chemistry 33, 181 , 1980), the firing of the CO 2 atmosphere and pressure In this case, the firing temperature is naturally high. This is because even under thermodynamic conditions, the decomposition temperature of the carbonate is higher than that in the air atmosphere under such conditions. On the other hand, there is a technique for lowering the decomposition temperature by firing an alkaline earth metal hydroxide, typically Ca (OH) 2 under reduced pressure (JP 2004-354414, JP 2006-21945). The same applies to carbonates, and the decomposition temperature can be lowered by baking under reduced pressure. Thus, although the result of baking of dolomite changes with baking conditions, the point is to perform baking so that the quantity of free calcium oxide and free magnesium oxide may enter into the above-mentioned range.
本発明の排水中のフッ素イオンを除去する方法は、本発明のフッ素イオンの除去剤をフッ素を含有する酸性の排水に接触させることからなるが、具体的にはさまざまな方法で実施することができる。そのひとつは、粉末状の除去剤を排水に投入して撹拌することにより、効率的にフッ素イオン除去剤の性能を発揮させることである。この目的には、フッ素イオン吸着後の排水からの除去剤粉末の固液分離に好都合なように、除去剤の粒度を適切に選ぶ必要がある。固液分離には適宜の凝集剤を使用するなど、排水処理の分野で確立された技術を利用することができる。 The method for removing fluorine ions in the wastewater of the present invention comprises contacting the fluorine ion removing agent of the present invention with acidic wastewater containing fluorine, and specifically, various methods can be used. it can. One of them is to efficiently exhibit the performance of the fluorine ion removing agent by putting the powdery removing agent into the waste water and stirring it. For this purpose, it is necessary to appropriately select the particle size of the removing agent so as to facilitate the solid-liquid separation of the removing agent powder from the waste water after adsorption of fluoride ions. For solid-liquid separation, techniques established in the field of wastewater treatment, such as using an appropriate flocculant, can be used.
いまひとつの、実施がより容易な態様は、除去剤を充填したカラムに排水を通す操作である。このためには、除去剤を、適宜の粒度であって、排水と除去剤との接触が十分である一方、フッ素イオンの吸着によっても崩壊することが少ないものにして使用することが必要である。具体的には、粒度を３〜７mmに調整したフッ素イオンの除去剤が好適である。この崩壊性を調べるには、前掲の特許文献３に記載された「注水顆粒維持率」試験法が有用である。その方法は、２〜５mmサイズの試料を２５個選び、５００ｍＬの常温の水中に投入して２４時間後に顆粒の形状を維持している粒子の数を数えることからなる。崩壊の割合は、５％以下であることが望ましい。
Another embodiment that is easier to implement is an operation of passing waste water through a column filled with a removing agent. For this purpose, it is necessary to use the removing agent having an appropriate particle size and sufficient contact between the waste water and the removing agent, but with little destruction due to adsorption of fluorine ions. . Specifically, a fluorine ion remover having a particle size adjusted to 3 to 7 mm is suitable. In order to investigate this disintegration property, the “water injection granule maintenance rate” test method described in
上述の使用の態様から理解されるように、本発明のフッ素イオン除去剤は、適切な粒度の粒子として使用すべきである。除去性能の観点からは、できるだけ微細な粉末、具体的には１mm通過が好ましく、一方で、排水処理に使用したときに固体状態を維持することを期待される場合、たとえば通水カラムに充填したり、河床に敷き詰めたりするものは、より大径の、具体的には３〜７mm程度の破砕片が適切である。 As will be understood from the above-described use mode, the fluoride ion removing agent of the present invention should be used as particles of an appropriate particle size. From the viewpoint of removal performance, it is preferable to pass as fine a powder as possible, specifically 1 mm. On the other hand, when it is expected to maintain a solid state when used for wastewater treatment, for example, it is packed in a water flow column. Or, those that are spread on the riverbed are suitably larger pieces, specifically about 3 to 7 mm.
表１に示す組成をもつドロマイトを原料として使用し、これを７００℃、７５０℃または８００℃において種々の時間焼成して、有効石灰量および遊離酸化マグネシウムの値が異なる半焼成ドロマイトを得た。得られた半焼成ドロマイトのＭｇＯ含有量および遊離酸化マグネシウム量を、焼成条件とともに表２に示す。この除去剤について、前掲の特許文献３に記載の「注水顆粒維持率」測定法に従って排水と接触させたときに崩壊する可能性を調べたところ、いずれの試料にも崩壊が認められず、形状を維持する特性が高いことがわかった。
（表２において、原石の遊離酸化カルシウム量が０．１重量％となっているのは、分析誤差である。）
Dolomite having the composition shown in Table 1 was used as a raw material and calcined at 700 ° C., 750 ° C. or 800 ° C. for various times to obtain semi-calcined dolomite having different effective lime content and free magnesium oxide values. Table 2 shows the MgO content and free magnesium oxide content of the obtained semi-baked dolomite together with the baking conditions. The removal agent was examined for the possibility of disintegration when contacted with drainage according to the method for measuring the “poured granule maintenance rate” described in
(In Table 2, it is an analysis error that the amount of free calcium oxide in the raw stone is 0.1% by weight.)
表１ 重量％
表２
フッ素イオン含有排水のシミュレート溶液として、フッ化ナトリウムＮａＦを水に溶解した、フッ素イオン濃度が２０mg／Ｌの水溶液を用意した。この溶液５００mLに対して上記の半焼成ドロマイト各２ｇを投入し、マグネチックスターラーで撹拌してフッ素イオンの除去を行なった。２４時間後の液のフッ素イオン濃度を測定して、表３に示す結果を得た。表３には、フッ素イオンの除去率を併せて示し、遊離ＭｇＯの値を再度掲げる。 As a simulated solution of fluorine ion-containing wastewater, an aqueous solution having a fluoride ion concentration of 20 mg / L in which sodium fluoride NaF was dissolved in water was prepared. 2 g each of the above-mentioned semi-baked dolomite was added to 500 mL of this solution and stirred with a magnetic stirrer to remove fluorine ions. The fluorine ion concentration of the liquid after 24 hours was measured, and the results shown in Table 3 were obtained. Table 3 also shows the removal rate of fluorine ions, and lists the value of free MgO again.
表３
フッ素イオン除去剤中に含まれる遊離酸化カルシウムの量と、２４時間後の液のフッ素イオン濃度との関係をプロットして、図１に示すグラフを得た。同様に、フッ素イオン除去剤中に含まれる遊離酸化マグネシウムの量と、２４時間後の液のフッ素イオン濃度との関係をプロットして、図２に示すグラフを得た。 The relationship between the amount of free calcium oxide contained in the fluorine ion removing agent and the fluorine ion concentration of the liquid after 24 hours was plotted to obtain the graph shown in FIG. Similarly, the relationship between the amount of free magnesium oxide contained in the fluorine ion removing agent and the fluorine ion concentration of the liquid after 24 hours was plotted to obtain the graph shown in FIG.
上記したところと同様にして、フッ素イオン濃度が２０mg／Ｌのフッ化ナトリウム水溶液を用意した。この溶液５００mLに消石灰２ｇを投入し、撹拌下に２４時間保ってＣａ（ＯＨ）２によるフッ素イオンの除去を行なった。その結果、液中のＦ−濃度は９．９mg／Ｌに減少した。この、消石灰によるフッ素イオンの一部除去を行なった溶液に、上のフッ素イオン除去試験で最もよい成績を収めた試料Ｎｏ．５の粉末を２ｇ投入し、撹拌状態に保って、２時間、４時間、８時間および２４時間後の液のフッ素イオン濃度を測定した。比較のため、同量の消石灰を使用して、同様にフッ素イオンの除去を行なった。結果は表４および図３に示すとおりで、消石灰で処理した場合、フッ素イオン濃度に変化がなく、それ以上のフッ素イオン除去はできなかった。これに対して、半焼成ドロマイトで処理したものは、濃度が、５．３mg／Ｌに減少して、排水基準を容易に満たすところになった。 In the same manner as described above, an aqueous sodium fluoride solution having a fluorine ion concentration of 20 mg / L was prepared. 2 g of slaked lime was added to 500 mL of this solution, and the fluorine ions were removed with Ca (OH) 2 while being kept under stirring for 24 hours. As a result, the F − concentration in the liquid decreased to 9.9 mg / L. In this solution in which a part of fluorine ions was removed by slaked lime, Sample No. 2 g of the powder of No. 5 was added and kept in a stirring state, and the fluorine ion concentration of the liquid after 2 hours, 4 hours, 8 hours and 24 hours was measured. For comparison, fluorine ions were similarly removed using the same amount of slaked lime. The results are as shown in Table 4 and FIG. 3, and when treated with slaked lime, there was no change in the fluorine ion concentration, and it was not possible to remove more fluorine ions. On the other hand, what was processed with the semi-baked dolomite reduced the concentration to 5.3 mg / L, and easily reached the drainage standard.
表４ フッ素イオン濃度（mg／Ｌ）の経時変化
フッ素イオン除去剤の試料Ｎｏ．５を破砕ないし粉砕して、粒度がそれぞれ、（Ａ）２〜１mm、（Ｂ）２〜０．５mm、（Ｃ）１〜０．５mm、（Ｄ）０．５〜０．２１２mmまたは（Ｅ）０．２１２mm以下の５種類の除去剤とした。フッ素イオン濃度が２０mg／Ｌのフッ化ナトリウム水溶液の各５００mLに、これら粒度の異なる除去剤を投入して撹拌し、２時間、４時間、８時間および２４時間経過したときの液のフッ素イオン濃度を測定した。結果は図４のグラフに示すとおりであって、粗粒の試料（Ａ）および（Ｂ）を用いた場合は、２４時間経過後の液のフッ素イオン濃度は３〜４mg／Ｌであって、排水基準値８．０mg／Ｌを満たすことはできたが、環境基準値である０．８mg／Ｌを達成することはできなかった。それに対し、細粒の試料（Ｃ）〜（Ｅ）を用いた場合は、２４時間経過後の液のフッ素イオン濃度は０．５〜０．７mg／Ｌであって、上記の環境基準値をも満たす結果が得られた。 Sample No. of fluorine ion removing agent 5 is crushed or crushed, and the particle sizes are (A) 2 to 1 mm, (B) 2 to 0.5 mm, (C) 1 to 0.5 mm, (D) 0.5 to 0.212 mm, or (E ) Five types of removal agents of 0.212 mm or less were used. Fluorine ion concentration of the liquid when 2 hours, 4 hours, 8 hours, and 24 hours have passed after adding and removing these different particle size removers to 500 mL each of a sodium fluoride aqueous solution having a fluorine ion concentration of 20 mg / L. Was measured. The results are as shown in the graph of FIG. 4, and when using coarse-grained samples (A) and (B), the fluorine ion concentration of the liquid after 24 hours was 3 to 4 mg / L, Although it was possible to satisfy the wastewater standard value of 8.0 mg / L, the environmental standard value of 0.8 mg / L could not be achieved. On the other hand, when fine-grained samples (C) to (E) were used, the fluorine ion concentration of the liquid after 24 hours was 0.5 to 0.7 mg / L, and the environmental standard value was The result which also satisfies is obtained.
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| JP2013248594A (en) * | 2012-06-04 | 2013-12-12 | Yoshizawa Lime Industry | Cesium trapping material, and method for manufacturing the same |
| CN103949203A (en) * | 2014-04-30 | 2014-07-30 | 明光市恒大棒粉厂 | Preparation method of novel compound wastewater treatment adsorbing agent |
| JP2017080722A (en) * | 2015-10-30 | 2017-05-18 | Ｊｘ金属株式会社 | Method of removing fluorine in aqueous solution |
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| JP2012157834A (en) * | 2011-02-01 | 2012-08-23 | Yoshizawa Lime Industry | Removing agent for harmful substances in wastewater and removal method using the same |
| JP2013248594A (en) * | 2012-06-04 | 2013-12-12 | Yoshizawa Lime Industry | Cesium trapping material, and method for manufacturing the same |
| CN103949203A (en) * | 2014-04-30 | 2014-07-30 | 明光市恒大棒粉厂 | Preparation method of novel compound wastewater treatment adsorbing agent |
| JP2017080722A (en) * | 2015-10-30 | 2017-05-18 | Ｊｘ金属株式会社 | Method of removing fluorine in aqueous solution |
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