JP2005279413A - Elution inhibiter for hazardous element and fly ash subjected to elution inhibiting treatment of hazardous element using the same - Google Patents

Elution inhibiter for hazardous element and fly ash subjected to elution inhibiting treatment of hazardous element using the same Download PDF

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JP2005279413A
JP2005279413A JP2004095902A JP2004095902A JP2005279413A JP 2005279413 A JP2005279413 A JP 2005279413A JP 2004095902 A JP2004095902 A JP 2004095902A JP 2004095902 A JP2004095902 A JP 2004095902A JP 2005279413 A JP2005279413 A JP 2005279413A
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fly ash
mass
hazardous element
elution inhibitor
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JP4431664B2 (en
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Hiroshi Hasegawa
浩 長谷川
Teruhisa Maki
輝弥 牧
Kazumasa Ueda
一正 上田
Yukihiro Sugimoto
行弘 杉本
Takuji Shimizu
拓治 清水
Makoto Ikezaki
真 池▲崎▼
Shin Hanada
慎 花田
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ALPHA GREEN KK
Kanazawa University NUC
Hokuriku Electric Power Co
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Kanazawa University NUC
Hokuriku Electric Power Co
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an elution inhibiter of a hazardous element capable of suppressing the elution amount of the hazardous element in a waste material to an environmental quality standard value or below and fly ash subjected to elution inhibiting treatment of the hazardous element using the same. <P>SOLUTION: The elution inhibiter of the hazardous element contains an iron powder, calcium oxide and aluminum oxide as essential components, and specifically contains calcium oxide of 50 to 500 pts. mass and aluminum oxide of 20 to 200 pts. mass to the iron powder of 100 pts. mass. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は有害元素の溶出抑制剤と、それを用いて有害元素の溶出抑制処理が施されたフライアッシュに関し、更に詳しくは、例えば平成14年5月29日に公布された土壌汚染対策法に列記されている土壌汚染物質(主として重金属類)が溶出することを有効に防止することができ、そして同法で定める環境基準値を達成することができる新規な有害元素の溶出抑制剤と、それを用いて有害元素の溶出抑制処理が施されたフライアッシュに関する。   The present invention relates to a toxic element elution inhibitor and fly ash subjected to toxic element elution suppression treatment using the toxic element elution inhibitor, and more specifically, for example, to the soil contamination countermeasure method promulgated on May 29, 2002. A novel harmful element elution inhibitor that can effectively prevent the listed soil pollutants (mainly heavy metals) from leaching and achieve the environmental standard value stipulated by the law, and This relates to fly ash that has been subjected to a leaching suppression treatment of harmful elements.

産業廃棄物、下水汚泥、生活廃棄物などの廃棄物には、多種多様な有害元素が含まれているので、これらをそのまま廃棄すると、有害元素が雨水などによって環境に溶出して深刻な土壌汚染や水質汚染などの環境汚染を引き起こし、人体機能にも悪影響を及ぼす。
そのために、従来から、これら廃棄物を一旦セメントなどで固化したのち廃棄処理したり、また焼却処理して灰化し、それを例えばセメントで固化して廃棄処理するなどの対策がとられている。
Wastes such as industrial waste, sewage sludge, and domestic waste contain a wide variety of harmful elements. If they are discarded as they are, the harmful elements are eluted into the environment by rainwater and other serious soil contamination. It causes environmental pollution such as water pollution and adverse effects on human functions.
For this reason, conventionally, measures such as temporarily solidifying these wastes with cement or the like and then disposing them, or incinerating them into ash and solidifying them with cement, for example, are disposed of.

しかしながら、上記した処理を施しても、例えばセメント原料そのものにも有害元素が含まれていることがあり、また例えば廃棄物の焼却灰にも有害元素がそのまま残存しているので、時間が経過するにつれて、やはりこれらの有害元素が溶出してきて環境汚染を引き起こす。
このようなことを考えると、廃棄物に混合するだけで、当該廃棄物中に含まれている有害元素の溶出を抑制または防止することができる薬剤は、廃棄物を事実上無害化するという点で有用である。
However, even if the above-described treatment is performed, for example, the cement raw material itself may contain harmful elements, and for example, the harmful elements remain in the incineration ash of the waste, so that time elapses. As a result, these harmful elements are also eluted and cause environmental pollution.
In consideration of this, a chemical that can suppress or prevent the elution of harmful elements contained in the waste by simply mixing it with the waste effectively detoxifies the waste. It is useful in.

ところで、産業廃棄物の1種として、主成分がSiO2とAl23であるフライアッシュが知られている。
このフライアッシュは石炭火力発電所から発生する石炭灰であって、球形微粒子であり、ポラゾン活性を有しているので、例えばコンクリートの混和材として用いると、コンクリートの流動性向上、強度の向上、水密性の向上など、優れた効果を発揮する。
By the way, fly ash whose main components are SiO 2 and Al 2 O 3 is known as one kind of industrial waste.
This fly ash is coal ash generated from a coal-fired power plant, is a spherical fine particle, and has a porazone activity.For example, when used as an admixture for concrete, it improves the fluidity of concrete, improves strength, Excellent effects such as improved watertightness.

しかしながら、このフライアッシュには、やはり重金属類などの有害元素が含まれており、しかも微粒子であるため表面活性が大きいこともあって、重金属類の溶出量は、例えばクリンカアッシュのような他の石炭灰に比べて多いという問題がある。そのため、フライアッシュは、土木資材としての有用な性質を備えているにもかかわらず、それらの多くは、セメント原材料における粘土代替品として利用されたり、また埋立処分されているのが現状である。   However, since this fly ash also contains harmful elements such as heavy metals, and because it is fine particles, its surface activity may be large, and the amount of elution of heavy metals is other than clinker ash, for example. There is a problem that it is more than coal ash. Therefore, although fly ash has useful properties as civil engineering materials, many of them are currently used as clay substitutes in cement raw materials or are disposed of in landfills.

したがって、このようなフライアッシュに混合することにより、当該フライアッシュ中の有害元素の溶出量を環境基準値以下に抑制することができる溶出抑制剤は、フライアッシュを無害化して、その有用な性質を発揮させ、有用資源として再生させるという点でその工業的な価値は大きいといえる。
いずれにしても、フライアッシュをもその1種とする産業廃棄物に混合するだけで産業廃棄物中の有害元素を溶出させないか、また溶出したとしてもその溶出量を環境基準値以下に抑制することができるという作用効果を発揮する溶出抑制(防止)剤の開発は、環境保全の点と資源の有効利用の点の両面から強く求められている。
Therefore, an elution inhibitor that can suppress the elution amount of harmful elements in the fly ash below the environmental standard value by mixing with such fly ash makes the fly ash harmless and has useful properties. It can be said that its industrial value is great in that it can be used as a useful resource.
In any case, just mixing fly ash with industrial waste that is one of those types will not elute harmful elements in industrial waste, or even if it is eluted, the amount of elution will be kept below the environmental standard value. Development of an elution inhibitor (prevention) that exhibits the effect of being able to be performed is strongly demanded from both the viewpoints of environmental conservation and effective use of resources.

このような要請に応える溶出抑制剤として、現在、硫酸アルミニウム、チオ硫酸ナトリウム、および鉄粉を必須成分とするものが開発されている(特許文献1を参照)。
この溶出抑制剤の場合、その溶出抑制機構はいまだ明確になっているわけではないが、水分の存在下において、鉄粉が有する還元作用に基づいて進む有害元素の還元と、硫酸アルミニウムの加水分解とその重縮合イオンの生成との複合作用で有害元素の固定・不溶化を実現しているものと考えられる。
特許第3246661号公報
As elution inhibitors that meet such demands, those containing aluminum sulfate, sodium thiosulfate, and iron powder as essential components are currently being developed (see Patent Document 1).
In the case of this elution inhibitor, the elution suppression mechanism is not yet clear, but in the presence of moisture, the reduction of harmful elements that proceed based on the reducing action of iron powder and the hydrolysis of aluminum sulfate It is thought that fixation and insolubilization of harmful elements has been realized by the combined action of and the formation of polycondensation ions.
Japanese Patent No. 3246661

対象廃棄物としてフライアッシュを選定し、また溶出抑制の対象元素としてAs,B,Cd,Cr,Pb,Se,Fの7種類を設定し、これら元素に対する上記溶出抑制剤の溶出抑制効果について研究を重ねたところ、B以外の元素はいずれも溶出量を環境基準値以下に抑制することは可能であった。すなわち、Bに対しては、確かに溶出量は低減するとはいえ、環境基準値以下に抑制することは可成り困難であった。   Select fly ash as the target waste, and set 7 types of As, B, Cd, Cr, Pb, Se, F as the target elements of elution suppression, and study the elution suppression effect of the above elution inhibitor on these elements As a result, it was possible to suppress the amount of elution of elements other than B below the environmental standard value. That is, for B, although the elution amount is certainly reduced, it has been quite difficult to suppress it below the environmental standard value.

本発明は上記した知見を踏まえて開発された溶出抑制剤であって、廃棄物中の有害元素の、とりわけBの溶出量を環境基準値以下に抑制することができる新規な有害元素の溶出抑制剤と、それを用いることにより有用な資源として再生されたフライアッシュの提供を目的とする。   The present invention is an elution inhibitor developed on the basis of the above-described knowledge, and it is a novel elution inhibitor that can suppress the elution amount of harmful elements in waste, especially B, to an environmental standard value or less. The purpose of the present invention is to provide an agent and fly ash regenerated as a useful resource by using the agent.

上記した目的を達成するために、本発明においては、鉄粉、酸化カルシウム、および酸化アルミニウムを必須成分として含むことを特徴とする有害元素の溶出抑制剤が提供され、具体的には、前記鉄粉100質量部に対し、酸化カルシウム50〜500質量部、酸化アルミニウム20〜200質量部が含有されている有害元素の溶出抑制剤が提供される。
また、本発明においては、前記した有害元素の溶出抑制剤との混合物であることを特徴とする、有害元素の溶出抑制処理が施されたフライアッシュが提供される。
In order to achieve the above object, in the present invention, a harmful element elution inhibitor characterized by containing iron powder, calcium oxide, and aluminum oxide as essential components is provided. A harmful element elution inhibitor containing 50 to 500 parts by mass of calcium oxide and 20 to 200 parts by mass of aluminum oxide with respect to 100 parts by mass of the powder is provided.
Moreover, in this invention, it is a mixture with the above-mentioned harmful element elution inhibitor, The fly ash by which the elution suppression process of the harmful element was given is provided.

この溶出抑制剤と廃棄物とを混合すると、廃棄物中の有害元素がイオン種となって環境に溶出しても、溶出抑制剤の上記した必須3成分の相互作用により、これらイオン種は水和酸化物、無電荷の錯体、フッ化物として不溶化され、固定されて、環境中への溶出量は抑制される。   When this elution inhibitor and waste are mixed, even if harmful elements in the waste become ionic species and elute into the environment, these ionic species are not dissolved due to the interaction of the above three essential components of the elution inhibitor. It is insolubilized and fixed as a hydrated oxide, uncharged complex, and fluoride, and the amount of elution into the environment is suppressed.

最初に、本発明の溶出抑制剤の開発に関する技術思想について説明する。
本発明者らは、新たな溶出抑制剤を開発するための研究を進めるに当たり、溶出抑制対象の有害元素としてAs,B,Cd,Cr,Pb,Se,Fの7種類を設定した。これら有害元素の土壌環境基準値は環境庁告示第46号に規定されていて、それは表1で示したとおりである。
First, the technical idea relating to the development of the dissolution inhibitor of the present invention will be described.
In carrying out research for developing a new elution inhibitor, the present inventors set seven types of As, B, Cd, Cr, Pb, Se, and F as harmful elements for elution suppression. The soil environment standard values of these harmful elements are stipulated in Environment Agency Notification No. 46, which is as shown in Table 1.

Figure 2005279413
Figure 2005279413

そして、表1の環境基準値を実現する溶出抑制剤の開発研究の過程で、本発明者らは、有害元素の溶出抑制、すなわち不溶化に関して次のような考察を行った。
(1)廃棄物中の有害元素の溶出抑制という問題は、一般に、水分と大気(酸素)が存在する環境を前提として考察し、またセメント固化を考えればアルカリ性の環境を前提として考察すればよいと思われる。
In the course of the development and research of an elution inhibitor that realizes the environmental standard values shown in Table 1, the present inventors made the following considerations regarding the suppression of harmful element elution, that is, insolubilization.
(1) In general, the problem of suppressing the elution of harmful elements in waste can be considered on the premise of an environment in which moisture and air (oxygen) exist, and if considering cement solidification, an alkaline environment should be considered. I think that the.

(2)有害元素が廃棄物から溶出するということは、上記した含水アルカリ性環境中に、当該有害元素が陽イオンまたは陰イオンの形態をとることであると考えてよい。
例えば表1の元素でいえば、Cd2+,CrO4 2-,Pb2+,SeO4 2-や、AsO4 3-,F-の形態をとるだろう。ただし、主たる溶出抑制の対象であるBは、BO3 3-(ホウ酸イオン)の形態をとるであろう。
(2) Elution of a harmful element from waste may be considered to mean that the harmful element takes the form of a cation or an anion in the hydrous alkaline environment described above.
For example, the elements in Table 1 may take the form of Cd 2+ , CrO 4 2− , Pb 2+ , SeO 4 2− , AsO 4 3− , F . However, B which is the main target of elution suppression will take the form of BO 3 3− (borate ion).

(3)したがって、イオンの形態で環境に溶出している有害元素を、何らかの手段で捕捉して不溶化(固定化)することができれば、測定される有害元素の溶出量を環境基準値以下に低減することができるであろう。
(4)その場合、全体の環境は含水アルカリ性である。水自体も解離していて、OH-が存在していると考えられる。そして、その環境下では、Cd2+はCd(OH)2の水酸化物となって沈殿可能であり、またCrO4 2-はCr3+に還元してやれば、結局、CrO4 2-をCr(OH)3の水和酸化物の形態で沈殿させることが可能である。
(3) Therefore, if harmful elements eluted in the environment in the form of ions can be captured and insolubilized (fixed) by some means, the amount of harmful elements that are measured will be reduced below the environmental standard value. Would be able to.
(4) In that case, the entire environment is hydrous alkaline. Water itself is also dissociated, and it is considered that OH - is present. Then, in its environment, Cd 2+ is capable precipitate a Cd (OH) 2 hydroxide, also do it CrO 4 2-is reduced to Cr 3+, after all, CrO 4 2-a Cr It is possible to precipitate in the form of a hydrated oxide of (OH) 3 .

また、主たる対象になっているBの場合、ホウ酸イオンはCa,Mgなどのアルカリ土類金属との間で無電荷の錯体を形成することが知られている。そしてその錯体はFe・Al水和酸化物に吸着されることも知られている。
(5)このような考察を踏まえて、本発明者らは新たな溶出抑制剤の開発に関して次のような設計思想をもって対処した。
In the case of B, which is the main target, borate ions are known to form uncharged complexes with alkaline earth metals such as Ca and Mg. It is also known that the complex is adsorbed on Fe • Al hydrated oxide.
(5) Based on such considerations, the present inventors dealt with the development of a new dissolution inhibitor with the following design concept.

まず、ホウ酸イオンとして存在するBの溶出抑制に関しては、それを無電荷の錯体に転化してFe・Al水和酸化物に吸着させる。そのためには、Fe・Al水和酸化物を生成させるためのFe源とAl源を配合する。Al源としてAl23を選択する。
また、CrO4 2-に関しては、これをCr3+に還元して水和酸化物にし、それを前記したFe・Al水和酸化物と共沈させる。そのためには、CrO4 2-→Cr3+の還元反応を進める資材としては、Fe・Al水和酸化物の素材にもなり得る鉄粉を用いることにする。
First, regarding the suppression of elution of B existing as borate ions, it is converted to an uncharged complex and adsorbed on the Fe · Al hydrated oxide. For that purpose, an Fe source and an Al source for producing an Fe.Al hydrated oxide are blended. Al 2 O 3 is selected as the Al source.
As for CrO 4 2−, it is reduced to Cr 3+ to form a hydrated oxide, which is coprecipitated with the aforementioned Fe · Al hydrated oxide. For this purpose, iron powder that can also be a material of Fe · Al hydrated oxide is used as a material that promotes the reduction reaction of CrO 4 2− → Cr 3+ .

更に、ホウ酸イオンの錯体化に関しては、Ca,Mgなどのアルカリ土類金属が必要であるが、F-との間でCaF2を生成してFを固定することができるということで、そのアルカリ土類金属としてはCaを選択する。その場合、環境中に陰イオンが多くなると、同じ陰イオンであるホウ酸イオンの無電荷錯体への生成は進行しにくいので、Ca源としてはCaOを用いることにする。 Furthermore, for complexation of borate ions, alkaline earth metals such as Ca and Mg are required, but the fact that F can be generated by fixing CaF 2 with F , Ca is selected as the alkaline earth metal. In that case, when the amount of anions in the environment increases, the formation of borate ions, which are the same anions, into an uncharged complex does not proceed easily, so CaO is used as the Ca source.

そして、このCaOは、含水分環境中で解離して環境のアルカリ性を確保するという点でも好適であろう。
以上の設計思想に基づき、更に種々の研究を重ねた結果、前記した組成を有する本発明の溶出抑制剤が開発されたのである。
すなわち、本発明の溶出抑制剤は、鉄粉、酸化アルミニウム、酸化カルシウムを必須分とした混合物である。
And this CaO will be suitable also at the point of dissociating in a moisture-containing environment and ensuring the alkalinity of an environment.
As a result of further various studies based on the above design philosophy, the elution inhibitor of the present invention having the above-described composition was developed.
That is, the elution inhibitor of the present invention is a mixture containing iron powder, aluminum oxide, and calcium oxide as essential components.

そしてその溶出抑制剤は、有害元素を含む各種の廃棄物、汚染土壌などの処理対象物に混合して使用される。その場合、この溶出抑制剤は含水分のアルカリ性環境下で使用される。
ここで、この溶出抑制剤の溶出抑制機構を図1に基づいて説明する。
(1)まず第1の必須成分である鉄粉は、含水アルカリ性環境に溶出してFe2+となり、ついで大気中の酸素によって酸化されてFe3+になる。そして、環境中のOH-と反応してFe(OH)3の水和酸化物になって不溶化し、沈殿する。
And the elution inhibitor is used by mixing with various kinds of waste containing harmful elements, treatment objects such as contaminated soil. In that case, this elution inhibitor is used in a moisture-containing alkaline environment.
Here, the elution suppression mechanism of this elution inhibitor will be described with reference to FIG.
(1) First, iron powder, which is the first essential component, is eluted into a hydrous alkaline environment to become Fe 2+ , and then oxidized by oxygen in the atmosphere to become Fe 3+ . Then, it reacts with OH in the environment to become a hydrated oxide of Fe (OH) 3 , insolubilizes and precipitates.

一方、鉄粉は環境中に溶出しているCrO4 2-を還元してCr3+にする。そしてこのCr3+は環境中のOH-と反応してCr(OH)3の水和酸化物になって不溶化し、Fe(OH)3と共沈する。
(2)第2の必須成分であるAl23は、その一部が解離してAl3+を生成する。そしてこのAl3+は、環境中のOH-と反応してAl(OH)3の水和酸化物になって不溶化し、沈殿する。
On the other hand, iron powder reduces CrO 4 2- eluted in the environment to Cr 3+ . This Cr 3+ reacts with OH in the environment to become a hydrated oxide of Cr (OH) 3 , becomes insoluble, and coprecipitates with Fe (OH) 3 .
(2) Al 2 O 3 as the second essential component is partially dissociated to produce Al 3+ . The Al 3+ reacts with OH in the environment to become a hydrated oxide of Al (OH) 3 and becomes insoluble and precipitates.

(3)第3の必須成分であるCaOは、その一部が解離してCa2+を生成する。そしてこのCa2+はBO3 3-として環境中に溶出しているBと反応して、不溶化した無電荷の錯体Ca3(BO3)2を生成する。この錯体は、前記したFe(OH)3やAl(OH)3に吸着されて共沈する。
また、Ca2+は、F-として存在するFと反応して不溶化したCaF2を生成する。このCaF2は、上記した各種の水和酸化物に吸着される。
(3) A part of the third essential component, CaO, is dissociated to generate Ca 2+ . This Ca 2+ reacts with B eluted in the environment as BO 3 3− to produce an insoluble, uncharged complex Ca 3 (BO 3 ) 2 . This complex is adsorbed on the Fe (OH) 3 and Al (OH) 3 and coprecipitated.
Ca 2+ reacts with F existing as F to produce insolubilized CaF 2 . This CaF 2 is adsorbed by the various hydrated oxides described above.

一方、CaOは、環境全体のアルカリ性を促進し、溶出しているCd2+とOH-の反応を進めることにより、不溶化したCd(OH)2の水酸化物を生成する。このCd(OH)2は各種の水和酸化物と吸着・共沈する。
(4)なお、As,Pb,Seなども、やはり水酸化物に転化し、Fe(OH)3、Al(OH)3に吸着された状態で共沈する。
On the other hand, CaO promotes the alkalinity of the entire environment, and promotes the reaction between the eluted Cd 2+ and OH to generate insolubilized hydroxide of Cd (OH) 2 . This Cd (OH) 2 is adsorbed and co-precipitated with various hydrated oxides.
(4) As, Pb, Se, etc. are also converted into hydroxides and coprecipitated while adsorbed on Fe (OH) 3 and Al (OH) 3 .

このように、廃棄物中の有害元素が環境中に溶出しても、本発明の溶出抑制剤における各必須成分の上記した働きにより、これら有害元素がいずれも不溶化した状態で例えば水和酸化物、無電荷の錯体、フッ化物の形態で環境中に固定されることになる。
本発明の溶出抑制剤における上記した3種類の必須成分の混合割合は、鉄粉100質量部に対し、酸化アルミニウム20〜200質量部、酸化カルシウム50〜500質量部に設定される。
Thus, even if harmful elements in the waste are eluted in the environment, for example, hydrated oxides in a state where all these harmful elements are insolubilized by the above-described action of each essential component in the elution inhibitor of the present invention. It will be fixed in the environment in the form of an uncharged complex, fluoride.
The mixing ratio of the above-described three essential components in the elution inhibitor of the present invention is set to 20 to 200 parts by mass of aluminum oxide and 50 to 500 parts by mass of calcium oxide with respect to 100 parts by mass of iron powder.

酸化アルミニウムが20質量部より少ない場合には、上記した溶出抑制機構において、Al(OH)3の水和酸化物の生成量が不足して、有害元素が充分に吸着・共沈しなくなるという問題が生じ、また200質量部より多くしても、有害元素の溶出抑制効果は飽和に達し、無駄になるからである。
また酸化カルシウムが50質量部より少ない場合は、BO3 3-やF-の固定を充分に行うことができず、例えばBの溶出量を確実に環境基準値以下にすることが困難となり、逆に500質量部より多い場合は、環境のアルカリ性が強くなって溶存するイオンの総量が多くなることにより、有害元素の脱着が進むというような不都合が生じてくるからである。
When the amount of aluminum oxide is less than 20 parts by mass, the above-described elution suppression mechanism has a problem in that the amount of hydrated oxide of Al (OH) 3 is insufficient, and harmful elements are not sufficiently adsorbed and co-precipitated. This is because, even if the amount exceeds 200 parts by mass, the elution suppressing effect of harmful elements reaches saturation and is wasted.
In addition, when the amount of calcium oxide is less than 50 parts by mass, BO 3 3− and F cannot be sufficiently fixed. For example, it becomes difficult to ensure that the elution amount of B is less than the environmental standard value. If the amount is more than 500 parts by mass, the environmental alkalinity becomes stronger and the total amount of dissolved ions increases, resulting in inconvenience that desorption of harmful elements proceeds.

なお、混合割合の基準になる鉄粉の使用量は、対象とする廃棄物における有害元素の含有量、主要にはCrの含有量を勘案して決めればよい。
また、鉄粉としては、例えばRDL−300(商品名、パウダーテック社製)、E−200(商品名、和光純薬社製)を使用することができる。そして、CrO4 2-の還元反応やFe水和酸化物の生成という問題からすると、粒子径が小さい方が有効である。具体的には80メッシュ(タイラー篩)下のものが好適である。
The amount of iron powder used as a standard for the mixing ratio may be determined in consideration of the content of harmful elements in the target waste, mainly the content of Cr.
As the iron powder, for example, RDL-300 (trade name, manufactured by Powdertech) or E-200 (trade name, manufactured by Wako Pure Chemical Industries, Ltd.) can be used. From the viewpoint of the reduction reaction of CrO 4 2− and the generation of Fe hydrated oxide, the smaller the particle diameter, the more effective. Specifically, those under 80 mesh (Tyler sieve) are suitable.

また、酸化アルミニウムとしては、例えばキシダ化学社製(特級)のものが好適であり、酸化カルシウムとしては例えば和光純薬社製(特級)のものが好適である。
本発明の溶出抑制剤は、上記した3成分を必須成分とするが、廃棄物の種類や、その中の有害物質の種類や量によっては、硫酸アルミニウム、硫酸カルシウム、活性炭、シリカゲル、ゼオライト、セメント、鉄鉱スラグ、微粉砕した天然鉱物(例えばカオリナイト、モンモリロナイトなど)の1種または2種以上が配合されていてもよい。
Further, as aluminum oxide, for example, those manufactured by Kishida Chemical Co. (special grade) are suitable, and as calcium oxide, for example, those manufactured by Wako Pure Chemical Industries (special grade) are suitable.
The elution inhibitor of the present invention comprises the above-mentioned three components as essential components, but depending on the type of waste and the type and amount of harmful substances therein, aluminum sulfate, calcium sulfate, activated carbon, silica gel, zeolite, cement In addition, one or more of iron ore slag and finely pulverized natural minerals (for example, kaolinite, montmorillonite, etc.) may be blended.

本発明では、上記した溶出抑制剤を用いて有害元素の溶出抑制処理が施されたフライアッシュが提供される。
具体的には、この溶出抑制剤とフライアッシュを混合して有害元素の溶出抑制処理が施されたフライアッシュが製造される。このときの混合割合は、フライアッシュにおける有害物質の種類や量によって適宜に選択されるが、概ね、フライアッシュ100質量部に対し、本発明の溶出抑制剤を0.5〜10質量部程度混合すればよい。
In this invention, the fly ash by which the elution suppression process of the harmful element was performed using the above-mentioned elution inhibitor is provided.
Specifically, the elution inhibitor and fly ash are mixed to produce fly ash that has been subjected to the elution suppression treatment of harmful elements. The mixing ratio at this time is appropriately selected depending on the type and amount of harmful substances in fly ash, but generally about 0.5 to 10 parts by mass of the elution inhibitor of the present invention is mixed with 100 parts by mass of fly ash. do it.

得られた混合物は、本発明の溶出抑制剤がフライアッシュ中の有害元素の溶出量を環境基準値以下にするので、有害元素の溶出が抑制されたフライアッシュになっている。
したがって、この有害元素の溶出抑制処理が施されたフライアッシュは、例えば地盤改良材、融雪材、土壌改良材に使用することにより、環境汚染を心配することなく、フライアッシュが有する優れた性質を発揮させることができる。
The obtained mixture is fly ash in which the elution of the harmful element is suppressed because the elution inhibitor of the present invention makes the elution amount of the harmful element in the fly ash less than the environmental standard value.
Therefore, the fly ash that has been subjected to the leaching control of harmful elements can be used, for example, as a ground improvement material, snow melting material, and soil improvement material, so that the excellent properties of fly ash can be obtained without worrying about environmental pollution. It can be demonstrated.

A火力発電所のフライアッシュA2.0gと超純水(pH5.8〜6.3)18mLをテフロン(登録商標)容器中で混合し、温度20℃において、毎分約200回の振とう回数、振とう幅4〜5cmの条件で2時間振とうし、その後、1日静置した。
ついで、上澄液を採取して試料水とし、その試料水におけるAs,B,Cd,Cr,Pb,Se,Fを表2で示した分析方法で定量した。結果を表2に示す。
A thermal power plant fly ash A2.0 g and ultrapure water (pH 5.8 to 6.3) 18 mL are mixed in a Teflon (registered trademark) container and shaken at a temperature of 20 ° C. about 200 times per minute. The mixture was shaken for 2 hours under conditions of a shaking width of 4 to 5 cm, and then allowed to stand for 1 day.
Next, the supernatant was sampled and used as sample water, and As, B, Cd, Cr, Pb, Se, and F in the sample water were quantified by the analysis method shown in Table 2. The results are shown in Table 2.

一方、RDL−300(鉄粉)20mg、酸化カルシウム粉50mg、酸化アルミニウム粉10mgを均一に混合して溶出抑制剤を調製した。
この溶出抑制剤とフライアッシュA2.0gと超純水18mLとをテフロン容器中で混合し、上記溶出試験と同様の条件の溶出試験を行い、各有害元素を定量した。結果を表2に示した。
On the other hand, 20 mg of RDL-300 (iron powder), 50 mg of calcium oxide powder, and 10 mg of aluminum oxide powder were uniformly mixed to prepare an elution inhibitor.
This elution inhibitor, 2.0 g of fly ash A, and 18 mL of ultrapure water were mixed in a Teflon container, and an elution test under the same conditions as the above elution test was performed to quantify each harmful element. The results are shown in Table 2.

Figure 2005279413
Figure 2005279413

表2から明らかなように、フライアッシュAに実施例の溶出抑制剤を混合すると、有害元素の溶出量は、全て環境基準値以下の値となっていて、実施例の溶出抑制剤の有用性は明白である。
また、フライアッシュAとこの溶出抑制剤の混合物からは、有害元素の溶出が抑制されるので、当該フライアッシュAは無害化しており、有用資源として再使用が可能な状態になっている。
As is apparent from Table 2, when the elution inhibitor of the example was mixed with fly ash A, the amount of harmful elements eluted was all below the environmental standard value, and the usefulness of the elution inhibitor of the example was Is obvious.
Further, since the elution of harmful elements is suppressed from the mixture of fly ash A and this elution inhibitor, the fly ash A is rendered harmless and is in a state that can be reused as a useful resource.

RDL−300(鉄粉)20mg、酸化カルシウム粉50mg、酸化アルミニウム粉30mgを混合して溶出抑制剤を調製した。
フライアッシュ2gと上記の溶出抑制剤100mgを混合し、ここに、塩酸でpH調整した検液を添加し、実施例1の条件で振とうし、各pH値におけるB、Cr、As、Cdの溶出量を測定した。
An elution inhibitor was prepared by mixing 20 mg of RDL-300 (iron powder), 50 mg of calcium oxide powder, and 30 mg of aluminum oxide powder.
2 g of fly ash and 100 mg of the above elution inhibitor are mixed, and a test solution adjusted to pH with hydrochloric acid is added thereto, shaken under the conditions of Example 1, and B, Cr, As, and Cd at each pH value are mixed. The amount of elution was measured.

その結果は以下のとおりであった。
主たる溶出抑制の対象元素であるBの場合は、pH12以下で環境基準値以上の溶出が認められた。Crの場合はpH4以下、Asの場合はpH9以下、そしてCdの場合はpH8以下で、それぞれ、環境基準値以上の溶出が認められた。
このことから、本発明の溶出抑制剤は、アルカリ性の環境下で使用すべきであることがわかる。その場合、溶出抑制対象の有害元素の種類に応じてpH値を調整することが好ましい。
The results were as follows.
In the case of B, which is the main element for suppressing elution, elution exceeding pH 12 was observed at pH 12 or lower. In the case of Cr, elution above the environmental standard value was observed at pH 4 or less, in the case of As, pH 9 or less, and in the case of Cd, pH 8 or less.
This shows that the elution inhibitor of the present invention should be used in an alkaline environment. In that case, it is preferable to adjust the pH value according to the type of harmful element to be suppressed.

本発明の溶出抑制剤は、例えばフライアッシュに混合して使用すると、当該フライアッシュに含まれている有害元素を不溶化してその溶出量を環境基準値以下に抑制することができる。またそのことにより、従来は産業廃棄物として廃棄されていたフライアッシュを再生し、有用資源としての利用を可能にする。   When the elution inhibitor of the present invention is used by mixing with fly ash, for example, the harmful elements contained in the fly ash can be insolubilized and the amount of elution can be suppressed below the environmental standard value. In addition, this makes it possible to regenerate fly ash, which has been discarded as industrial waste, and use it as a useful resource.

本発明の溶出抑制剤の溶出抑制機構を示す模式図である。It is a schematic diagram which shows the elution suppression mechanism of the elution inhibitor of this invention.

Claims (4)

鉄粉、酸化カルシウム、および酸化アルミニウムを必須成分として含むことを特徴とする有害元素の溶出抑制剤。   A toxic element elution inhibitor comprising iron powder, calcium oxide, and aluminum oxide as essential components. 前記鉄粉100質量部に対し、酸化カルシウム50〜500質量部、酸化アルミニウム20〜200質量部が含有されている請求項1の有害元素の溶出抑制剤。   The harmful element elution inhibitor according to claim 1, wherein 50 to 500 parts by mass of calcium oxide and 20 to 200 parts by mass of aluminum oxide are contained with respect to 100 parts by mass of the iron powder. 更に、硫酸アルミニウム、硫酸カルシウム、活性炭、シリカゲル、ゼオライト、セメント、鉄鉱スラグ、および微粉砕した天然鉱物の群から選ばれる少なくとも1種が含有されている請求項1または2の有害元素の溶出抑制剤。   The harmful element elution inhibitor according to claim 1 or 2, further comprising at least one selected from the group consisting of aluminum sulfate, calcium sulfate, activated carbon, silica gel, zeolite, cement, iron ore slag, and finely pulverized natural minerals. . 請求項1〜3のいずれかの有害元素の溶出抑制剤との混合物であることを特徴とする、有害元素の溶出抑制処理が施されたフライアッシュ。
A fly ash subjected to a toxic element elution suppression process, wherein the fly ash is a mixture with the toxic element elution inhibitor of any one of claims 1 to 3.
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