JP5187376B2 - Removal agent for heavy metal ions in waste water and method for removing heavy metal ions using the same - Google Patents

Removal agent for heavy metal ions in waste water and method for removing heavy metal ions using the same Download PDF

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JP5187376B2
JP5187376B2 JP2010253320A JP2010253320A JP5187376B2 JP 5187376 B2 JP5187376 B2 JP 5187376B2 JP 2010253320 A JP2010253320 A JP 2010253320A JP 2010253320 A JP2010253320 A JP 2010253320A JP 5187376 B2 JP5187376 B2 JP 5187376B2
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heavy metal
metal ions
dolomite
waste water
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JP2011240325A (en
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辰郎 成瀬
陽一 赤堀
俊治 村樫
正道 辻
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Yoshizawa Lime Industry Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
    • B01J20/041—Oxides or hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
    • B01J20/043—Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28004—Sorbent size or size distribution, e.g. particle size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3021—Milling, crushing or grinding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00—Aspects relating to sorbent materials
    • B01J2220/50—Aspects relating to the use of sorbent or filter aid materials
    • B01J2220/58—Use in a single column
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Hydrology & Water Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Water Treatment By Sorption (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Removal Of Specific Substances (AREA)

Description

本発明は、半焼成ドロマイトを有効成分とし、排水中の重金属イオンを除去するための除去剤と、それを使用した重金属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で、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 removing agent for removing heavy metal ions in waste water, using semi-baked dolomite as an active ingredient, and a method for removing heavy metal ions 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 form magnesium oxide, while calcium carbonate 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やメッキ工場などから排出される排水には、フッ素イオンや、さまざまな重金属が主としてイオンの形で含有されている。また、工場跡地などの土壌が重金属で汚染されていることもある。工場排水からフッ素および重金属を除去して無害化する方法は種々検討されており、その中で石灰を利用する方法を挙げれば、フッ素に関しては消石灰を添加してフッ化カルシウムに変えて除去する方法があり、重金属類に関しては消石灰と無機系凝集剤を加え、凝集沈殿法により除去する方法がある。 For example, wastewater discharged from semiconductor manufacturing plants, plating plants, and the like contains fluorine ions and various heavy metals mainly in the form of ions. In addition, soil such as factory sites may be contaminated with heavy metals. Various methods of detoxification by removing fluorine and heavy metals from industrial wastewater have been studied. Among them, the method of using lime is a method of adding slaked lime and replacing it with calcium fluoride. As for heavy metals, there is a method in which slaked lime and an inorganic flocculant are added and removed by a coagulation precipitation method.

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、この点を改善するため、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。 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, by simply treating with calcium salt. Therefore, in order to improve this point, a method for treating fluorine-containing wastewater using a magnesium oxide compound has been 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比表面積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 waste water using magnesium oxide is to magnify magnesium oxide with a BET specific surface area of 40 to 200 m 2 / g by baking magnesium hydroxide at 700 to 1000 ° C. After adding to the wastewater of pH 4.0 or less to contain and processing at the temperature of 10-25 degreeC, it consists of adding a flocculant and carrying out solid-liquid separation (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。 A “fluoride ion scavenger” using calcined dolomite has been proposed with the intention of advantageously using quick lime having the ability to remove fluoride ions and magnesium oxide (Patent Document 3). This trapping material is a “moderate decomposition rate dolomite”, which is mainly composed of MgO, CaO and CaCO 3 baked at a temperature of 600 to 880 ° C., and 1.5 to 47 wt.% Of undecomposed carbon dioxide. % And can be used to reduce the concentration of fluorine ions remaining in the wastewater and also to reduce the amount of elution from soil contaminated with fluorine.

一方、重金属の処理に関しては、やはり消石灰で排水のｐＨを高めて、重金属を水酸化物として分離する方法があるが、鉛のような両性金属は高いｐＨで水酸化物が再溶解してしまうので、処理できる対象が限定される。汚染土壌やゴミ焼却灰中の重金属の固定化処理には、キレート剤が使用されるが、キレート剤は高価であるから、使用できる場面は限定される。そこで、吸着剤としてゼオライトを利用し、その細孔内に有害重金属を取り込んだ上でゼオライトを加熱して細孔の開口部を閉鎖し、有害物質を封入した形で安定化する技術が開示された（特許文献４）。別の方法としては、水酸化鉄（III）の沈殿を含む溶液にアルギン酸ナトリウムを添加し、その溶液をカルシウム塩溶液で固定して得たゲル状体を使用し、ヒ素や鉛のような有害な重金属を除去する技術もある（特許文献５）。 On the other hand, with regard to the treatment of heavy metals, there is also a method of separating the heavy metals as hydroxides by increasing the pH of the wastewater with slaked lime, but the amphoteric metals such as lead are dissolved again at a high pH. Therefore, the object which can be processed is limited. A chelating agent is used for immobilizing heavy metals in contaminated soil and garbage incineration ash, but the chelating agent is expensive, so the scenes that can be used are limited. Therefore, a technique is disclosed in which zeolite is used as an adsorbent, toxic heavy metals are taken into the pores, the zeolite is heated, the pore openings are closed, and toxic substances are enclosed. (Patent Document 4). Another method is to use a gel-like material obtained by adding sodium alginate to a solution containing iron (III) hydroxide precipitate and fixing the solution with a calcium salt solution. There is also a technique for removing heavy metals (Patent Document 5).

発明者らの一部は、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が１．５重量％以下であることと、遊離酸化マグネシウムの量が７重量％以上であることの２点である。この排水中のフッ素イオンを除去する技術は、すでに提案した（特許文献６）。
特開２００５−３４２５７８ 特開２００７−１３６４２４ 特開２００８−０８０２２３ 特開２００１−２３８９８０ 特開２００１−３４０８７３ 特願２００９−１６４２９１ Some of the inventors have researched a technique that uses dolomite calcined and 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 8.0 mg / L and can reliably achieve 0.8 mg / L, which is an environmental standard value related to water pollution, “undecomposed carbon dioxide is 1.5 to We have experienced that the rough limitation such as “47% by weight baked dolomite” is incomplete, and the properties need to be more finely defined. The inventors found as a matter to be limited that the amount of free calcium oxide in the half-baked dolomite is 1.5% by weight or less and the amount of free magnesium oxide is 7% by weight or more. Is a point. A technique for removing fluorine ions in the waste water has already been proposed (Patent Document 6).
JP-A-2005-342578 JP2007-136424 JP2008-080223 JP2001-238980 JP2001-340873 Japanese Patent Application No. 2009-164291

研究を続けた発明者らは、上記の排水中のフッ素イオンを除去するのに適した半焼成ドロマイトが、排水中の重金属イオンの除去に対しても有用であることを見出した。 The inventors who have continued research have found that the above-mentioned semi-calcined dolomite suitable for removing fluorine ions in waste water is also useful for removing heavy metal ions in waste water.

本発明の目的は、上記した発明者らが得た新しい知見を活用し、排水中の重金属イオンを除去して、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重金属除去剤を提供し、それによって効果的な排水処理を実現することにある。実用面からいえば、本発明の目的は、排水中に重金属イオンが含まれている場合に、それらを除去する排水処理の技術を提供することが主たる目的であり、重金属で汚染された土壌を浄化する技術を提供することが従たる目的である。 The purpose of the present invention is to make use of the new knowledge obtained by the above-mentioned inventors, remove heavy metal ions in waste water, and achieve a certain effect in satisfying the environmental standard value. The object is to provide a heavy metal removal agent comprising dolomite, thereby realizing an effective waste water treatment. From a practical point of view, the object of the present invention is to provide wastewater treatment technology for removing heavy metal ions in the case where heavy metal ions are contained in the wastewater. It is a secondary objective to provide technology for purification.

本発明に従う排水中の重金属イオンの除去剤は、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１．２重量％以下であって、遊離の酸化マグネシウムの含有量が８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 removal agent for heavy metal ions in waste water according to the present invention is obtained by baking dolomite, the content of free calcium oxide is 1.2% by weight or less, and the content of free magnesium oxide is 8% by weight. Preferably, the remover contains semi-calcined dolomite that is 19% by weight or more as an active ingredient.

本発明に従う排水中の重金属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除去剤を、重金属イオンを含有する排水に接触させることからなる。汚染土壌中の重金属を除去する場合は、半焼成ドロマイトを有効成分とする除去剤を、汚染土壌と混和して、その中の重金属を固定化することからなる。 The basic aspect of the method for removing heavy metal ions in waste water according to the present invention comprises contacting a removing agent containing semi-calcined dolomite as an active ingredient with waste water containing heavy metal ions. When removing heavy metals in the contaminated soil, a removal agent containing semi-baked dolomite as an active ingredient is mixed with the contaminated soil to immobilize the heavy metals therein.

別の態様は、上記した半焼成ドロマイトを有効成分とする除去剤を管に充填して通液性のあるカラムを形成し、このカラムに重金属イオンを含有する排水を通過させて、その中の重金属を除去することからなる。 In another aspect, the removal agent containing the above-mentioned semi-baked dolomite as an active ingredient is filled into a tube to form a liquid-permeable column, and waste water containing heavy metal ions is passed through the column. Consisting of removing heavy metals.

本発明の重金属イオンの除去剤は、ドロマイトの半焼成により得られ、高い重金属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 heavy metal ion removal agent of the present invention is obtained by semi-firing dolomite, exhibits high heavy metal 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.

本発明の方法に従い、半焼成ドロマイトを有効成分とする重金属イオン除去剤を使用して排水処理を行なえば、排水中の重金属イオンを効果的に除去することができるから、各種の重金属イオンの濃度を、のぞましい限度以下に、すなわち、ヒ素、カドミウム、鉛およびセレンについては、健康項目として０．０１mg／Ｌ、亜鉛については「水生生物の保全に係る環境基準」として定められた、０．０３mg／Ｌの限度以下に低減することが可能である。 According to the method of the present invention, if wastewater treatment is performed using a heavy metal ion remover containing semi-baked dolomite as an active ingredient, heavy metal ions in the wastewater can be effectively removed, so the concentration of various heavy metal ions Is less than the recommended limit, that is, 0.01 mg / L as a health item for arsenic, cadmium, lead and selenium, and 0.03 mg / L as defined as “Environmental standards for the conservation of aquatic organisms” It can be reduced below the limit of L.

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（重量％）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重量％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重量％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重量％未満のとき：遊離酸化マグネシウムの量は、［分析で得たＭｇＯ重量％−ＭｇＣＯ３として存在するＭｇＯ重量％］によって算出する。ＭｇＣＯ３として存在するＭｇＯ重量％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 “The 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 (% by weight) 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% by weight.
When the amount of free calcium oxide is 1.5% by weight or more: The value of MgO obtained by analysis is adopted as the amount of free magnesium oxide as it is.
When the amount of free calcium oxide is less than 1.5% by weight: The amount of free magnesium oxide is calculated by [MgO wt% obtained by analysis−MgO wt% present as MgCO 3 ]. MgO wt% present as MgCO 3 is
{Ig.loss%-(CaO% ÷ 56 × 44)} ÷ 44 × 40
Ask for.

排水中の重金属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。従って、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、重金属イオンの除去に適切なｐＨを実現しやすいことにある。すなわち、ＣａＣＯ３の脱炭酸が進んでＣａＯが多量に生成すると、半焼成ドロマイトを添加した液のｐＨが上昇しすぎてしまい、両性金属である亜鉛や鉛の再溶出が起こってしまう。一般に、これらの金属水酸化物の溶解度が最も低いｐＨは９〜１０であるといわれている。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 heavy metal 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 that it is easy to achieve a pH suitable for removing heavy metal ions. That is, if the decarboxylation of CaCO 3 proceeds and a large amount of CaO is produced, the pH of the liquid to which the semi-baked dolomite is added rises too much and re-elution of the amphoteric metals zinc and lead occurs. In general, the pH at which the solubility of these metal hydroxides is lowest is said to be 9-10. 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、生成量が少ないと、半焼成ドロマイトを添加した液のｐＨが中性付近に止まって重金属の除去が実現できない。さきに開示したように、フッ素イオンの除去を、不相当に多量の半焼成ドロマイトを消費しないで行なうには、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った。遊離酸化マグネシウムの量が１０重量％あれば、半焼成ドロマイトを添加した液のｐＨは９程度になり、重金属の除去に効果的である。後記する実施例で用いた半焼成ドロマイトは、遊離酸化マグネシウムを２０重量％程度含有し、液のｐＨが１０となって、十分である。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、かえって好ましくない。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。 If the amount of free magnesium oxide produced is small, the pH of the liquid to which semi-baked dolomite is added stops near neutral, and removal of heavy metals cannot be realized. As previously disclosed, in order to remove fluorine ions without consuming a relatively large amount of semi-calcined dolomite, it was necessary that the semi-calcined dolomite contained at least 7% by weight free magnesium oxide. It was. If the amount of free magnesium oxide is 10% by weight, the pH of the solution to which semi-baked dolomite is added is about 9, which is effective for removing heavy metals. The semi-baked dolomite used in the examples described later contains about 20% by weight of free magnesium oxide, and the pH of the solution is 10, which is sufficient. In principle, the higher the content of free magnesium oxide, the more advantageous. However, if calcination of dolomite is excessively advanced in order to increase the value, the amount of free calcium oxide in the semi-calcined dolomite of the product is reduced. However, it is unfavorable. 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、排水中の重金属イオンの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。 A semi-calcined dolomite useful as a removal agent for heavy metal ions in waste water as described above, that is, a semi-calcined dolomite in which MgCO 3 is sufficiently decarboxylated while CaCO 3 is decarboxylated as much as possible is obtained. For this, selection of 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.

ドロマイトの焼成に適切な温度および時間は、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。焼成が適切であるか否かを知る一つの方法は、半焼成ドロマイトの粉末を水に分散させ、得られた液のｐＨを測定することであって、後記する実施例にみるように、ｐＨがおおよそ１０〜１２の範囲にあるものが、重金属イオンの除去にとって適切である。 The appropriate temperature and time for dolomite firing depend 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 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. One way of knowing if firing is appropriate is to disperse the semi-fired dolomite powder in water and measure the pH of the resulting liquid, as seen in the examples below. In the range of approximately 10-12 is suitable for removal of heavy metal ions.

本発明の排水中の重金属イオンを除去する方法は、本発明の除去剤を、重金属イオンを含有する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、効率的に除去剤の性能を発揮させることである。この目的には、重金属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。 Although the method for removing heavy metal ions in the waste water of the present invention comprises contacting the removing agent of the present invention with waste water containing heavy metal ions, specifically, it can be carried out by various methods. One of them is to efficiently exhibit the performance of the removing agent by introducing the powdered 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 heavy metal 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、重金属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０．５〜７mmに調整した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 degradation due to adsorption of heavy metal ions. . Specifically, a remover having a particle size adjusted to 0.5 to 7 mm is suitable. In order to investigate this disintegration property, the “water injection granule maintenance rate” test method described in Patent Document 3 is useful. The method consists of selecting 25 samples having a size of 2 to 5 mm, putting them in 500 mL of room temperature water, and counting the number of particles maintaining the shape of the granules after 24 hours. The rate of collapse is desirably 5% or less.

上述の使用の態様から理解されるように、本発明の重金属イオン除去剤は、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以下が好ましく、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するものは、０．５〜３ｍｍ程度が適切であり、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 can be understood from the above-described use modes, the heavy metal ion removing agent of the present invention should be used as particles of an appropriate particle size. From the viewpoint of removal performance, a powder as fine as possible, specifically 1 mm or less is preferable. 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. As for the thing, about 0.5-3 mm is suitable, and the thing laid on the riverbed is a larger diameter, specifically, about 3-7 mm.

重金属イオンの除去方法としては、さきに挙げた特許文献に記載のようなさまざまな処理方法があるが、鉛やカドミウムのような水中でカチオンの形態をとって存在するものは、水溶液のｐＨをアルカリ側にすることによって、水酸化物として沈殿させることができる。ただし、鉛のような両性元素は、強アルカリ性にしてｐＨが高くなると、再び溶解してしまう。しかし、本発明によって半焼成ドロマイトと水溶液を接触させれば、両性元素も高い率で除去することができる。 There are various methods for removing heavy metal ions as described in the above-mentioned patent documents, but those existing in the form of cations in water, such as lead and cadmium, can be adjusted to a pH of an aqueous solution. By setting it to the alkali side, it can precipitate as a hydroxide. However, amphoteric elements such as lead are dissolved again when the pH is increased by making them strongly alkaline. However, if the semi-baked dolomite is brought into contact with the aqueous solution according to the present invention, the amphoteric elements can also be removed at a high rate.

［製造例］
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℃、
８００℃または９００℃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。各半焼成ドロマイトを粉砕して、粒径２１２μｍ以下の粗粉末にした。それら粗粉末状の半焼成ドロマイト５ｇを２００ｍＬの水に分散させた液のｐＨを測定した。結果を表２にあわせて示す。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。 [Production example]
Dolomite having the composition shown in Table 1 is used as a raw material, and this is used at 700 ° C, 750 ° C,
By calcining at 800 ° C. or 900 ° C. for various times, semi-calcined dolomite with different amounts of effective lime and free magnesium oxide was obtained. Table 2 shows the MgO content and free magnesium oxide content of the obtained semi-baked dolomite together with the baking conditions. Each semi-baked dolomite was pulverized into a coarse powder having a particle size of 212 μm or less. The pH of a solution obtained by dispersing 5 g of these coarsely powdered semi-baked dolomite in 200 mL of water was measured. The results are shown in Table 2. 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 Patent Document 3 described above. It was found that the characteristics of maintaining the

表１ 原料ドロマイトの分析値 重量％

Figure 0005187376
Table 1 Analysis value of raw dolomite Weight%
Figure 0005187376

表２ 半焼成ドロマイトの分析値とｐＨ

Figure 0005187376
（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。）
Table 2 Analytical values and pH of semi-baked dolomite
Figure 0005187376
(In Table 2, it is an analysis error that the amount of free calcium oxide in the raw stone is 0.1% by weight.)

実施例１，２および比較例１〜４
［重金属イオン含有廃フッ酸液の処理］
フッ素イオンとともに種々の重金属イオンを含有する排水をシミュレートした溶液として、フッ化水素酸を水に溶解した液と、原子吸光分析用重金属標準液を希釈した液を使用して、
・フッ酸１５％、および
・ヒ素、セレン、亜鉛、鉛およびカドミウムを、いずれも２５mg／Ｌ
の濃度で含有する水溶液を用意した。 Examples 1 and 2 and Comparative Examples 1 to 4
[Treatment of waste metal hydrofluoric acid solution containing heavy metal ions]
Using a solution in which hydrofluoric acid is dissolved in water and a solution obtained by diluting a heavy metal standard solution for atomic absorption analysis as a solution simulating wastewater containing various heavy metal ions together with fluorine ions,
・ 15% hydrofluoric acid, and ・ Arsenic, selenium, zinc, lead and cadmium, 25mg / L
An aqueous solution containing a concentration of was prepared.

このシミュレーション溶液３００ｇに対して、上記の半焼成ドロマイト（試料番号１〜６）を、フッ素イオンに対して等倍量となるように投入し、マグネチックスターラーで撹拌して、フッ素イオンおよび重金属イオンの除去を行なった。２４時間経過後に液を採取し、濾過して、得られた濾液について、それぞれ下記の分析法により、各種イオンの濃度を測定した。
フッ素イオン：イオンクロマトグラフィー
カドミウム、亜鉛および鉛：ＩＣＰ−ＡＥＳ
ヒ素およびセレン：水素化物発生原子吸光法
表３に示す結果を得た。表３には、表２のｐＨの値を再掲する。 With respect to 300 g of this simulation solution, the above-mentioned semi-baked dolomite (sample numbers 1 to 6) is added so as to have an equal volume with respect to fluorine ions, and stirred with a magnetic stirrer to obtain fluorine ions and heavy metal ions Was removed. After 24 hours, the liquid was collected and filtered, and the concentration of various ions was measured for each of the obtained filtrates by the following analytical methods.
Fluorine ion: ion chromatography Cadmium, zinc and lead: ICP-AES
Arsenic and selenium: hydride generation atomic absorption method The results shown in Table 3 were obtained. Table 3 shows the pH values in Table 2 again.

表３ 実施例１，２および比較例１〜４の結果

Figure 0005187376
イオンの濃度はｍｇ／Ｌ
Table 3 Results of Examples 1 and 2 and Comparative Examples 1 to 4
Figure 0005187376
Ion concentration is mg / L

実施例３〜６および比較例５，６
上記の結果によれば、実施例Ｎｏ．２すなわち試料番号４の半焼成ドロマイトを使用した場合の成績が最良であったので、以下、この試料を使用することとした。前記のシミュレーション溶液３００ｇに対して、半焼成ドロマイト（試料番号４）を、フッ素イオンに対して、当量（１．０倍）、１．５倍、１．７倍または２．０倍に相当する量投入し、同様に、マグネチックスターラーで撹拌してフッ素イオンおよび重金属イオンの除去を行なった。比較のため、ＪＩＳ ９００１規定の「工特消石灰」、「特号軽焼ドロマイト」を、それぞれフッ素イオンに対して当量加えた場合も試験した。ここで、「当量」とは、フッ素２モルに、カルシウム１モルとマグネシウム１モルを合わせたものが対応すると考え、Ｆの１モルに対してＣａ＋Ｍｇが０．５モル存在するとき、当量（１．０倍）関係にある、と定めた語である。 Examples 3 to 6 and Comparative Examples 5 and 6
According to the above results, Example No. 2, that is, the result when the semi-baked dolomite of sample number 4 was used was the best, so this sample was used hereinafter. Semi-calcined dolomite (sample number 4) corresponds to equivalent (1.0 times), 1.5 times, 1.7 times, or 2.0 times with respect to fluorine ions with respect to 300 g of the simulation solution. In the same manner, fluorine ions and heavy metal ions were removed by stirring with a magnetic stirrer. For comparison, a test was also conducted in the case where “Especial slaked lime” and “Special light burnt dolomite” defined in JIS 9001 were added in an equivalent amount to fluorine ions. Here, it is considered that “equivalent” corresponds to 2 mol of fluorine plus 1 mol of calcium and 1 mol of magnesium, and when 0.5 mol of Ca + Mg is present per 1 mol of F, the equivalent (1 .0 times) is a word that is related.

２４時間経過後に液を採取し、濾過して、得られた濾液について、下記の分析法により、各種イオンの濃度を測定した。
フッ素イオン：イオンクロマトグラフィー
カドミウム、亜鉛および鉛：ＩＣＰ−ＡＥＳ
ヒ素およびセレン：水素化物発生原子吸光法
表４に示す結果を得た。 After 24 hours, the liquid was collected and filtered, and the concentration of various ions was measured for the obtained filtrate by the following analysis method.
Fluorine ion: ion chromatography Cadmium, zinc and lead: ICP-AES
Arsenic and selenium: hydride generation atomic absorption method The results shown in Table 4 were obtained.

表４ 重金属イオンの除去

Figure 0005187376
重金属の濃度はｍｇ／Ｌ
Table 4 Removal of heavy metal ions
Figure 0005187376
Heavy metal concentration is mg / L

表４にみるように、本発明の半焼成ドロマイトを使用すれば、既知の軽焼ドロマイトや消石灰を使用した場合に比べ、有害な重金属イオンを効果的に除去することができる。半焼成ドロマイトの添加量は、フッ素イオンに対して当量の１．５倍以上とすることが望ましいことがわかった。 As shown in Table 4, when the semi-baked dolomite of the present invention is used, harmful heavy metal ions can be effectively removed as compared with the case where known light-burned dolomite or slaked lime is used. It was found that the amount of semi-baked dolomite added is desirably 1.5 times or more equivalent to fluorine ions.

前記した「当量」の定め方においては、フッ素に対してＣａとＭｇとを対等な存在として扱ったが、実際のフッ酸と半焼成ドロマイトとの反応においては、フッ素とＣａ化合物との反応が支配的であってＭｇＯとの反応はあまり進まないこと、つまり、フッ素イオンの大部分はＣａＦ２として固定され、ＭｇＦ２の生成はわずかであることが、生成物のＸ線回折分析によりわかっている。ＭｇＯの作用としては、Ｍｇ(ＯＨ)２を形成して、それがフッ素イオンを吸着するという機構が考えられるが、発明者らは確認するに至っていない。とはいえ、半焼成ドロマイトによる処理は、上記のデータが示すように、消石灰や軽焼ドロマイトを使用したときよりも、フッ素イオンや重金属の溶存濃度を低くすることができ、この理由は、半焼成ドロマイトを水中に投入したときのｐＨが低いことと、Ｍｇの補助的な役割とが効果的に働いているためと考えられる。 In the method of determining the “equivalent”, Ca and Mg are treated as being equal to fluorine, but in the actual reaction between hydrofluoric acid and semi-baked dolomite, the reaction between fluorine and the Ca compound occurs. dominant was that the reaction between the MgO does not proceed too much and, in other words, most of the fluoride ions are fixed as CaF 2, that the production of MgF 2 is slightly, found by X-ray diffraction analysis of the product Yes. As the action of MgO, a mechanism in which Mg (OH) 2 is formed and adsorbs fluorine ions can be considered, but the inventors have not confirmed it. However, the treatment with semi-calcined dolomite can lower the dissolved concentration of fluoride ions and heavy metals than when using slaked lime or light calcined dolomite, as shown in the above data. This is probably because the pH when the calcined dolomite is put into water is low and the auxiliary role of Mg works effectively.

実施例７
［フッ素イオンと重金属イオンの完全除去］
上記の実施例５の試験で得た濾液１００ｇに対して、本発明の半焼成ドロマイト（試料番号４）をそれぞれ０．４ｇ、０．８ｇ、１．０ｇまたは１．２ｇ添加し、撹拌下に２４時間置いた後、残存するフッ素イオン濃度を測定した。結果は表５のとおりであって、濾液１００ｇに対して半焼成ドロマイトを１．０ｇ添加したＮｏ．３の場合、フッ素イオン濃度を排水基準値である８．０mg／Ｌより低くすることができた。 Example 7
[Complete removal of fluorine ions and heavy metal ions]
0.4 g, 0.8 g, 1.0 g or 1.2 g of the semi-baked dolomite of the present invention (sample No. 4) is added to 100 g of the filtrate obtained in the test of Example 5 above, and the mixture is stirred. After 24 hours, the remaining fluorine ion concentration was measured. The results are as shown in Table 5. No. obtained by adding 1.0 g of semi-baked dolomite to 100 g of the filtrate. In the case of 3, the fluorine ion concentration could be made lower than the wastewater standard value of 8.0 mg / L.

表５ 実施例７におけるフッ素イオンの除去

Figure 0005187376
Table 5 Removal of fluorine ions in Example 7
Figure 0005187376

表５のＮｏ．３の処理水中の重金属イオンの濃度を測定したところ、いずれも環境基準値以下である０．０１mg／Ｌに達しない濃度に低減されていた。 No. in Table 5 When the concentration of heavy metal ions in the treated water of No. 3 was measured, all were reduced to a concentration not reaching 0.01 mg / L, which is below the environmental standard value.

このように、重金属イオン含有廃フッ酸液をいったん半焼成ドロマイトで処理してから、その濾液に対して再度半焼成ドロマイトを作用させるという二段処理を行なった場合、すぐれたフッ素イオン除去効果が得られる理由としては、二段目の処理において、前述したＭｇ(ＯＨ)２の生成による吸着作用が役立っていると考えられる。消石灰を作用させる処理ではＣａＦ２が生成するだけであって、この物質は溶解度が比較的高いため、フッ素イオン処理の効果にはおのずから限界があるが、半焼成ドロマイトを用いた二段処理では、二段目において一段目と異なる機構がはたらいて、高い成績が得られるわけである。 In this way, when the waste metal hydrofluoric acid solution containing heavy metal ions is once treated with semi-calcined dolomite and then subjected to the semi-calcined dolomite again on the filtrate, excellent fluorine ion removal effect is obtained. The reason for this is considered that the adsorption action by the above-described production of Mg (OH) 2 is useful in the second stage treatment. In the treatment with slaked lime, only CaF 2 is produced, and since this substance has a relatively high solubility, the effect of the fluorine ion treatment is naturally limited, but in the two-stage treatment using semi-baked dolomite, A mechanism different from the first stage works in the second stage, and high results are obtained.

実施例８，９および比較例７
［重金属イオンの除去］
半焼成ドロマイトによる重金属イオンの除去能力を評価するため、カドミウム、鉛、亜鉛、ヒ素およびセレンを、０．８６〜０．８９mg／Ｌの範囲で含有する模擬溶液を用意した。それぞれの溶液模擬溶液２５０ｍＬに、本発明の半焼成ドロマイト（試料番号４）を２ｇまたは１０ｇ投入して、１時間撹拌した。その後、液を濾過し、濾液中の各重金属の濃度を測定した。比較例３として、上記の各溶液と同じ溶液に水酸化ナトリウムを加え、溶液のｐＨを１０．５としたものをも用意した。１０．５というｐＨは、半焼成ドロマイトを２ｇ添加した溶液が呈するｐＨの値である。これについても１時間撹拌したのち液を濾過し、濾液中の各重金属の濃度を測定した。 Examples 8 and 9 and Comparative Example 7
[Removal of heavy metal ions]
In order to evaluate the ability to remove heavy metal ions by semi-baked dolomite, a simulated solution containing cadmium, lead, zinc, arsenic and selenium in the range of 0.86 to 0.89 mg / L was prepared. 2 g or 10 g of the semi-baked dolomite of the present invention (Sample No. 4) was added to 250 mL of each solution simulation solution and stirred for 1 hour. Thereafter, the liquid was filtered, and the concentration of each heavy metal in the filtrate was measured. As Comparative Example 3, a solution in which sodium hydroxide was added to the same solution as the above solutions to adjust the pH of the solution to 10.5 was also prepared. A pH of 10.5 is a pH value exhibited by a solution to which 2 g of semi-baked dolomite is added. Also for this, after stirring for 1 hour, the liquid was filtered, and the concentration of each heavy metal in the filtrate was measured.

測定値は表６に示すとおりであって、半焼成ドロマイトの２ｇの投入（実施例８）で、カチオン形態の重金属がいずれも除去され、１０ｇ投入したとき（実施例９）は、アニオン形態の重金属の濃度をも、環境基準値以下にすることができた。とくに注目すべきは、実施例８および９のどちらにおいても、両性元素とりわけＰｂの溶存濃度が０．０１ｍｇ／Ｌを下回っていることであって、ＮａＯＨの添加により同等のｐＨにしても達成できない重金属イオンの除去が、半焼成ドロマイトを用いた、１時間の処理によって実現する。 The measured values are as shown in Table 6. When 2 g of semi-baked dolomite was charged (Example 8), all heavy metals in the cation form were removed, and when 10 g was charged (Example 9), The concentration of heavy metals could also be reduced below the environmental standard value. Of particular note is that, in both Examples 8 and 9, the dissolved concentration of amphoteric elements, particularly Pb, is below 0.01 mg / L, which cannot be achieved even with the addition of NaOH. Removal of heavy metal ions is achieved by a one hour treatment using semi-baked dolomite.

表６ 実施例８，９および比較例７における重金属イオンの除去

Figure 0005187376
濃度はｍｇ／Ｌ
Table 6 Removal of heavy metal ions in Examples 8 and 9 and Comparative Example 7
Figure 0005187376
Concentration is mg / L

実施例１０〜１３
［重金属含有溶液のカラム吸着試験］
半焼成ドロマイト（試料番号４）を破砕ないし粉砕し、粒径分布がそれぞれ下記の範囲である、４種の粒状物とした。
粗粒：２．０〜３．０ｍｍ
中粒：１．０〜２．０ｍｍ
細粒：０．５〜１．０ｍｍ
混粒：０．５〜２．０ｍｍ Examples 10-13
[Column adsorption test of heavy metal-containing solution]
Semi-baked dolomite (Sample No. 4) was crushed or pulverized to obtain 4 types of granular materials each having a particle size distribution within the following range.
Coarse grain: 2.0-3.0mm
Medium grain: 1.0-2.0mm
Fine grain: 0.5-1.0mm
Mixed grain: 0.5-2.0mm

内径が２０ｍｍで長さが３００ｍｍの管内に、上記４種の半焼成ドロマイト粒状物を充填して、吸着カラムを形成した。実施例８および９で使用した模擬溶液、すなわち、カドミウム、亜鉛、鉛、セレンおよびヒ素をそれぞれ０．５mg／Ｌ含有する模擬溶液を、これらのカラムに上方から下方に向かって流下させ、通水速度（ＳＶ値）が１０となるように通水して、流下した模擬溶液に含有される重金属イオンの濃度を測定した。結果は表７に記載のとおりであって、吸着剤となる半焼成ドロマイトとして細粒の形態のものを用いれば、もっとも効果的に重金属イオンを除去することができることがわかった。しかし、通水量の確保や生産性の点からは、混粒の方が有利である。粗粒は、上記の通水条件では除去効果が不十分であった。 The above four kinds of semi-baked dolomite granular materials were filled in a tube having an inner diameter of 20 mm and a length of 300 mm to form an adsorption column. The simulated solutions used in Examples 8 and 9, ie, simulated solutions each containing 0.5 mg / L of cadmium, zinc, lead, selenium and arsenic were allowed to flow downward from above to these columns, Water was passed so that the speed (SV value) was 10, and the concentration of heavy metal ions contained in the simulated solution was measured. The results are as shown in Table 7. It was found that heavy metal ions can be most effectively removed by using finely baked dolomite serving as an adsorbent. However, mixed grains are more advantageous from the viewpoint of securing the water flow rate and productivity. The effect of removing the coarse particles was insufficient under the above water flow conditions.

表７ 実施例１０〜１３における重金属イオンの除去

Figure 0005187376
濃度はｍｇ／Ｌ Table 7 Removal of heavy metal ions in Examples 10-13
Figure 0005187376
Concentration is mg / L

Claims (8)

ドロマイトを焼成して得られた、遊離酸化カルシウムの含有量が１．２重量％以下であって、遊離酸化マグネシウムの含有量が８重量％以上である半焼成ドロマイトを有効成分とする排水中の重金属イオンの除去剤。 In the wastewater containing semi-calcined dolomite having an active ingredient content of 1.2% by weight or less and a free magnesium oxide content of 8% by weight or more, obtained by firing dolomite. Heavy metal ion remover. ドロマイトを、温度６００〜９００℃に０．５〜４８時間焼成し、破砕または粉砕してなる請求項１の排水中の重金属イオンの除去剤。 The remover of heavy metal ions in waste water according to claim 1, wherein the dolomite is calcined at a temperature of 600 to 900 ° C for 0.5 to 48 hours, crushed or pulverized. 葛生産のドロマイトを温度７００〜８００℃に２〜２４時間焼成し、破砕または粉砕してなる請求項２の排水中の重金属イオンの除去剤。 The remover of heavy metal ions in waste water according to claim 2, wherein the dolomite produced by Kuzu is calcined at a temperature of 700 to 800 ° C for 2 to 24 hours, crushed or pulverized. 粉砕して粒径１mm以下に調整してなる、請求項１ないし３のいずれかの排水中の重金属イオンの除去剤。 The agent for removing heavy metal ions in waste water according to any one of claims 1 to 3, which is pulverized and adjusted to a particle size of 1 mm or less. 粉砕して粒径分布を０．５〜３mmの範囲に調整してなる、請求項１ないし３のいずれかの排水中の重金属イオンの除去剤。 The agent for removing heavy metal ions in waste water according to any one of claims 1 to 3, which is pulverized to adjust the particle size distribution to a range of 0.5 to 3 mm. 請求項４に記載した除去剤を、重金属イオンを含有する排水中に投入して撹拌することにより接触させることからなる排水中の重金属イオンの除去方法。 A method for removing heavy metal ions in wastewater, comprising bringing the removing agent according to claim 4 into contact with wastewater containing heavy metal ions by stirring. 請求項５に記載した除去剤を管に充填して通液性のあるカラムを形成し、このカラムに重金属イオンを含有する排水を通過させることからなる排水中の重金属イオンの除去方法。 A method for removing heavy metal ions in waste water, comprising filling a tube with the removing agent according to claim 5 to form a liquid-permeable column, and allowing waste water containing heavy metal ions to pass through the column. 除去すべき重金属イオンが、亜鉛、鉛、セレン、カドミウムおよびヒ素の１種または２種以上である請求項６または７の排水中の重金属イオンの除去方法。 The method for removing heavy metal ions in waste water according to claim 6 or 7, wherein the heavy metal ions to be removed are one or more of zinc, lead, selenium, cadmium and arsenic.
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