JP2020138131A - Solidification insolubilization method - Google Patents
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Abstract
Description
本発明は、固化不溶化方法に関する。 The present invention relates to a solidification insolubilization method.
火力発電所で発生する石炭灰等の焼却灰を、盛土材、埋戻し材、地盤改質材等の土工資材として有効利用する方法が検討されている。
しかし、石炭灰等の焼却灰には、カドミウム、六価クロム、シアン、水銀、セレン、鉛、ひ素、フッ素、又は、ホウ素（以下、「重金属等」ともいう。）等が含まれている場合がある。このため、焼却灰から重金属等が溶出し、土壌が重金属等で汚染されるという問題がある。
石炭灰中の重金属等の溶出を抑制する方法として、特許文献１には、石炭灰に対し、硫酸第一鉄及び高炉セメントＢ種を添加し、さらにスラリー化する量の水を添加して混練することを特徴とする、石炭灰中の重金属不溶化方法が記載されている。
また、焼却灰中のフッ素、又は、ホウ素の溶出を防止する方法として、特許文献２には、フッ素あるいはホウ素が溶出する土壌又はフッ素あるいはホウ素が溶出する焼却灰に水硬性結合材を添加、混合することを特徴とする土壌又は焼却灰中のフッ素又はホウ素の固化不溶化方法が記載されている。
また、焼却灰中の重金属類の溶出が抑制された固化不溶化体として、特許文献３には、重金属類を含む焼却灰、酸化マグネシウム含有物質、鉄化合物、及び水を含むことを特徴とする固化不溶化体が記載されている。
A method of effectively utilizing incineration ash such as coal ash generated at a thermal power plant as an earthwork material such as an embankment material, a backfill material, and a ground modifier is being studied.
However, when incineration ash such as coal ash contains cadmium, hexavalent chromium, cyanide, mercury, selenium, lead, arsenic, fluorine, or boron (hereinafter, also referred to as "heavy metal"). There is. Therefore, there is a problem that heavy metals and the like are eluted from the incineration ash and the soil is contaminated with the heavy metals and the like.
As a method for suppressing elution of heavy metals and the like in coal ash, Patent Document 1 states that ferrous sulfate and blast furnace cement type B are added to coal ash, and water in an amount to be slurried is added and kneaded. A method for insolubilizing heavy metals in coal ash is described.
Further, as a method for preventing the elution of fluorine or boron in the incineration ash, Patent Document 2 includes adding and mixing a water-hard binder to the soil in which fluorine or boron is eluted or the incineration ash in which fluorine or boron is eluted. A method for solidifying and insolubilizing fluorine or boron in soil or incineration ash is described.
Further, as a solidified insolubilizer in which the elution of heavy metals in the incinerated ash is suppressed, Patent Document 3 contains incinerated ash containing heavy metals, a magnesium oxide-containing substance, an iron compound, and water. Insolubilized products are listed.
本発明の目的は、重金属類を含む焼却灰を含むにもかかわらず、重金属類の溶出が抑制された固化不溶化体を製造することができる方法を提供することである。 An object of the present invention is to provide a method capable of producing a solidified insolubilized product in which elution of heavy metals is suppressed even though it contains incineration ash containing heavy metals.
本発明者は、上記課題を解決するために鋭意検討した結果、鉄化合物と水を混合して鉄化合物水溶液を得た後、該鉄化合物水溶液と、重金属類を含む焼却灰と、酸化マグネシウム含有物質を同時に混合して固化不溶化体を得る方法であって、鉄化合物等の量が特定の値である方法によれば、上記目的を達成できることを見出し、本発明を完成した。
すなわち、本発明は、以下の［１］〜［３］を提供するものである。
［１］ 鉄化合物と水を混合して鉄化合物水溶液を得る第一の混合工程と、上記鉄化合物水溶液と、重金属類を含む焼却灰と、酸化マグネシウム含有物質を同時に混合して、固化不溶化体を得る第二の混合工程、を含む固化不溶化方法であって、上記焼成灰１００質量部に対して、上記鉄化合物と上記酸化マグネシウム含有物質の合計量が３５〜１００質量部、上記水の量が１５〜１００質量部であり、上記鉄化合物及び上記酸化マグネシウム含有物質の少なくともいずれか一方の量が、上記焼却灰１００質量部に対して、２０質量部を超えるものであることを特徴とする固化不溶化方法。
［２］ 上記第一の混合工程における、上記鉄化合物と上記水の質量比（鉄化合物／水）が、４．０以下である前記［１］に記載の固化不溶化方法。
［３］ 上記鉄化合物が、塩化第一鉄、塩化第二鉄、硫酸第一鉄、硫酸第二鉄、及びポリ硫酸第二鉄からなる群より選ばれる少なくとも１種である前記［１］又は［２］に記載の固化不溶化方法。
As a result of diligent studies to solve the above problems, the present inventor has obtained an iron compound aqueous solution by mixing an iron compound and water, and then contains the iron compound aqueous solution, incineration ash containing heavy metals, and magnesium oxide. The present invention has been completed by finding that the above object can be achieved by a method of simultaneously mixing substances to obtain a solidified insolubilized product in which the amount of an iron compound or the like is a specific value.
That is, the present invention provides the following [1] to [3].
[1] A solidified insolubilized product by simultaneously mixing the first mixing step of mixing an iron compound and water to obtain an iron compound aqueous solution, the above iron compound aqueous solution, incineration ash containing heavy metals, and a magnesium oxide-containing substance. The solidification and insolubilization method including the second mixing step of obtaining the above, wherein the total amount of the iron compound and the magnesium oxide-containing substance is 35 to 100 parts by mass and the amount of water is 100 parts by mass of the fired ash. Is 15 to 100 parts by mass, and the amount of at least one of the iron compound and the magnesium oxide-containing substance exceeds 20 parts by mass with respect to 100 parts by mass of the incinerated ash. Solidification and insolubilization method.
[2] The solidification and insolubilization method according to the above [1], wherein the mass ratio (iron compound / water) of the iron compound to the water in the first mixing step is 4.0 or less.
[3] The iron compound is at least one selected from the group consisting of ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate. The solidification and insolubilization method according to [2].
本発明の固化不溶化方法によれば、重金属類を含む焼却灰を含むにもかかわらず、重金属類の溶出量の低い固化不溶化体を得ることができる。このため、得られた固化不溶化材を、盛土材、埋戻し材及び地盤改質材等の土工資材等として使用しても、土壌が重金属類によって汚染されるおそれがない。 According to the solidification insolubilization method of the present invention, a solidification insolubilizer having a low elution amount of heavy metals can be obtained even though it contains incineration ash containing heavy metals. Therefore, even if the obtained solidified insolubilizing material is used as an earthwork material such as an embankment material, a backfill material, and a ground modifier, there is no possibility that the soil will be contaminated by heavy metals.
本発明の固化不溶化方法は、鉄化合物と水を混合して鉄化合物水溶液を得る第一の混合工程と、鉄化合物水溶液と、重金属類を含む焼却灰と、酸化マグネシウム含有物質を同時に混合して、固化不溶化体を得る第二の混合工程を含む固化不溶化方法であって、焼成灰１００質量部に対して、鉄化合物と酸化マグネシウム含有物質の合計量が３５〜１００質量部、水の量が１５〜１００質量部であり、鉄化合物及び酸化マグネシウム含有物質の少なくともいずれか一方の量が、焼却灰１００質量部に対して、２０質量部を超えるものである。
以下、本発明を工程ごとに詳細に説明する。
In the solidification and insolubilization method of the present invention, the first mixing step of mixing an iron compound and water to obtain an iron compound aqueous solution, an iron compound aqueous solution, incineration ash containing heavy metals, and a magnesium oxide-containing substance are simultaneously mixed. A solidification and insolubilization method including a second mixing step of obtaining a solidified insolubilized substance, wherein the total amount of the iron compound and the magnesium oxide-containing substance is 35 to 100 parts by mass and the amount of water is 100 parts by mass of the fired ash. It is 15 to 100 parts by mass, and the amount of at least one of the iron compound and the magnesium oxide-containing substance exceeds 20 parts by mass with respect to 100 parts by mass of the incinerated ash.
Hereinafter, the present invention will be described in detail for each step.
［第一の混合工程］
本工程は、鉄化合物と水を混合して鉄化合物水溶液を得る工程である。
本発明において用いられる鉄化合物の例としては、塩化第一鉄、塩化第二鉄、硫酸第一鉄、硫酸第二鉄、及びポリ硫酸第二鉄等が挙げられる。これらは一種を単独で用いてもよく、二種以上を組み合わせて用いてもよい。中でも、重金属類の溶出をより抑制する観点からは、塩化第一鉄が好ましい。また、鉄化合物にかかるコスト低減の観点からは、塩化第二鉄が好ましい。
本発明において、重金属類を含む焼却灰１００質量部に対する、鉄化合物の量は、好ましくは１０〜５０質量部、より好ましくは１５〜４５質量部、さらに好ましくは２０質量部を超え、４０質量部以下、さらに好ましくは２１〜３５質量部、特に好ましくは２２〜３５質量部である。該量が１０質量部以上であれば、重金属類の溶出をより抑制することができる。また、大量の焼却灰の固化不溶化処理を行う場合であっても、第一の混合工程及び第二の混合工程の混合において、鉄化合物が、鉄化合物水溶液及び固化不溶化体中に十分に分散されるため、鉄化合物がばらつく（偏在する）ことによる重金属類の溶出抑制効果の低下がより起こりにくくなる。該量が５０質量部以下であれば、鉄化合物にかかるコストの過度の上昇や固化不溶化処理後に発生する固化不溶化体の量が過度に増大することを防ぐことができる。
[First mixing step]
This step is a step of mixing an iron compound and water to obtain an aqueous iron compound solution.
Examples of the iron compound used in the present invention include ferric chloride, ferric chloride, ferrous sulfate, ferric sulfate, polyferric sulfate and the like. These may be used alone or in combination of two or more. Of these, ferrous chloride is preferable from the viewpoint of further suppressing the elution of heavy metals. Further, ferric chloride is preferable from the viewpoint of cost reduction of iron compounds.
In the present invention, the amount of the iron compound is preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, still more preferably more than 20 parts by mass and 40 parts by mass with respect to 100 parts by mass of incinerated ash containing heavy metals. Hereinafter, it is more preferably 21 to 35 parts by mass, and particularly preferably 22 to 35 parts by mass. When the amount is 10 parts by mass or more, elution of heavy metals can be further suppressed. Further, even when a large amount of incineration ash is solidified and insolubilized, the iron compound is sufficiently dispersed in the iron compound aqueous solution and the solidified insolubilized material in the mixing of the first mixing step and the second mixing step. Therefore, the effect of suppressing the elution of heavy metals due to the dispersion (uneven distribution) of the iron compounds is less likely to occur. When the amount is 50 parts by mass or less, it is possible to prevent an excessive increase in the cost of the iron compound and an excessive increase in the amount of the solidified insolubilized material generated after the solidified insolubilized treatment.
本発明において、重金属類を含む焼却灰１００質量部に対する、水の量は、好ましくは１５〜１００質量部、より好ましくは２５〜９５質量部、さらに好ましくは４０〜９０質量部、さらに好ましくは６０〜８５質量部、特に好ましくは７０〜８５質量部である。該量が１５質量部以上であれば、第一の混合工程及び第二の混合工程の混合において、鉄化合物のばらつき（偏在）が抑えられ、重金属類の溶出をより抑制することができる。該量が１００質量部以下であれば、固化不溶化体の保管や運搬がより容易となる。
本工程において、鉄化合物と混合される水は、次工程で得られる固化不溶化体に含まれることとなる水の全部であっても一部であってもよい。本工程において、鉄化合物と、固化不溶化体に含まれることとなる水の一部を混合した場合、残りの水は、次工程である第二の混合工程において、他の材料（重金属類等を含む焼却灰等）と共に混合される。
本工程で用いられる水の量は、本工程と次工程との合計の水の量（１００質量％中）に対して、好ましくは７０質量％以上、より好ましくは８０質量％以上、さらに好ましくは９０質量％以上、特に好ましくは１００質量％である。
本工程における、鉄化合物と水の質量比（鉄化合物／水）は、好ましくは４．０以下、より好ましくは３．０以下、さらに好ましくは２．０以下、さらに好ましくは１．５以下、特に好ましくは０．８以下である。該比が４．０以下であれば、鉄化合物を十分に水に溶解させることができ、重金属類の溶出をより抑制することができる。該比の下限値は、固化不溶化体の保管や運搬がより容易となる等の観点から、好ましくは０．１以上、より好ましくは０．２以上、特に好ましくは０．４以上である。
In the present invention, the amount of water is preferably 15 to 100 parts by mass, more preferably 25 to 95 parts by mass, still more preferably 40 to 90 parts by mass, still more preferably 60 parts by mass with respect to 100 parts by mass of incineration ash containing heavy metals. It is ~ 85 parts by mass, particularly preferably 70 to 85 parts by mass. When the amount is 15 parts by mass or more, the variation (uneven distribution) of the iron compound can be suppressed in the mixing of the first mixing step and the second mixing step, and the elution of heavy metals can be further suppressed. When the amount is 100 parts by mass or less, the solidified insolubilized material can be easily stored and transported.
In this step, the water mixed with the iron compound may be all or part of the water to be contained in the solidified insolubilized material obtained in the next step. When the iron compound and a part of the water to be contained in the solidified insolubilizer are mixed in this step, the remaining water is used for other materials (heavy metals, etc.) in the second mixing step, which is the next step. It is mixed with incineration ash, etc.).
The amount of water used in this step is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 80% by mass or more, based on the total amount of water (in 100% by mass) of this step and the next step. It is 90% by mass or more, particularly preferably 100% by mass.
The mass ratio of iron compound to water (iron compound / water) in this step is preferably 4.0 or less, more preferably 3.0 or less, still more preferably 2.0 or less, still more preferably 1.5 or less. Particularly preferably, it is 0.8 or less. When the ratio is 4.0 or less, the iron compound can be sufficiently dissolved in water, and the elution of heavy metals can be further suppressed. The lower limit of the ratio is preferably 0.1 or more, more preferably 0.2 or more, and particularly preferably 0.4 or more, from the viewpoint of facilitating storage and transportation of the solidified insolubilized material.
第一の混合工程における混合時間は、各材料の合計量やミキサ等の混合手段によっても異なるが、重金属類の溶出量をより小さくする観点から、好ましくは１分間以上、より好ましくは４分間以上である。 The mixing time in the first mixing step varies depending on the total amount of each material and the mixing means such as a mixer, but from the viewpoint of reducing the elution amount of heavy metals, it is preferably 1 minute or longer, more preferably 4 minutes or longer. Is.
［第二の混合工程］
本工程は、前工程で得られた鉄化合物水溶液と、重金属類を含む焼却灰と、酸化マグネシウム含有物質を同時に混合して、固化不溶化体を得る工程である。
重金属類としては、カドミウム及びその化合物、六価クロム化合物、シアン、水銀及びその化合物、セレン及びその化合物、鉛及びその化合物、ひ素及びその化合物、フッ素及びその化合物、及び、ホウ素及びその化合物（土壌汚染対策法（平成１５年）において第二種特定有害物質として挙げられているもの）が挙げられる。中でも、従来は不溶化が難しかった重金属類の不溶化を図ることができるという観点から、セレン及びひ素が好ましく、セレンがより好ましい。
本発明の固化不溶化方法の対象物である、重金属類を含む焼却灰の例としては、石炭灰、都市ごみ焼却灰、ペーパースラッジ焼却灰、炉清掃排出物、コークス灰、及び、重油燃焼灰等が挙げられる。
[Second mixing step]
This step is a step of simultaneously mixing the iron compound aqueous solution obtained in the previous step, the incineration ash containing heavy metals, and the magnesium oxide-containing substance to obtain a solidified insolubilized product.
Heavy metals include cadmium and its compounds, hexavalent chromium compounds, cyanide, mercury and its compounds, selenium and its compounds, lead and its compounds, arsenic and its compounds, fluorine and its compounds, and boron and its compounds (soil). Those listed as Class 2 Specified Hazardous Substances in the Pollution Control Law (2003) are listed. Of these, selenium and arsenic are preferable, and selenium is more preferable, from the viewpoint of being able to insolubilize heavy metals that have been difficult to insolubilize in the past.
Examples of incineration ash containing heavy metals, which are the objects of the solidification insolubilization method of the present invention, include coal ash, municipal waste incineration ash, paper sludge incineration ash, furnace cleaning waste, coke ash, and heavy oil combustion ash. Can be mentioned.
本発明で用いられる酸化マグネシウム含有物質中の酸化マグネシウムの含有率は、好ましくは２０質量％以上、より好ましくは５０質量％以上、さらに好ましくは８０質量％以上、特に好ましくは９０質量％以上である。該含有率が２０質量％以上であれば、重金属類の溶出をより抑制することができる。
酸化マグネシウム含有物質の例としては、軽焼マグネシア、軽焼マグネシアの部分水和物、軽焼ドロマイト、又は、軽焼ドロマイトの部分水和物を含むもの等が挙げられる。中でも、重金属類（特に、セレン）の溶出をより抑制することができ、不純物の含有量が少なく、かつ、入手の容易性の観点から、軽焼マグネシアが好ましい。
軽焼マグネシアの例としては、炭酸マグネシウムと水酸化マグネシウムのいずれか一方または両方を含む原料を、好ましくは６００〜１，３００℃の温度で焼成することによって得られるものが挙げられる。
軽焼ドロマイトとしては、例えば、ドロマイトを、好ましくは６５０〜１，１００℃の温度で焼成することによって得られるものが挙げられる。
The content of magnesium oxide in the magnesium oxide-containing substance used in the present invention is preferably 20% by mass or more, more preferably 50% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. .. When the content is 20% by mass or more, elution of heavy metals can be further suppressed.
Examples of magnesium oxide-containing substances include light-baked magnesia, light-burned magnesia partial hydrate, light-burned dolomite, and light-burned dolomite partially hydrated. Among them, light-baked magnesia is preferable from the viewpoint of being able to further suppress the elution of heavy metals (particularly selenium), having a low impurity content, and being easily available.
Examples of light-baked magnesia include those obtained by firing a raw material containing either or both of magnesium carbonate and magnesium hydroxide, preferably at a temperature of 600 to 1,300 ° C.
Examples of the lightly baked dolomite include those obtained by firing dolomite at a temperature of preferably 650 to 1,100 ° C.
軽焼マグネシアまたは軽焼ドロマイトの部分水和物は、軽焼マグネシアまたは軽焼ドロマイトを粉砕した後、当該粉砕物に水を添加して撹拌し混合するか、または、当該粉砕物を相対湿度８０％以上の雰囲気下に１週間以上保持して、軽焼マグネシアまたは軽焼ドロマイトを部分的に水和させることによって得ることができる。 The partial hydrate of light-baked magnesia or light-baked dolomite is obtained by crushing light-baked magnesia or light-baked dolomite and then adding water to the crushed product and stirring and mixing, or the crushed product having a relative humidity of 80. It can be obtained by partially hydrating light-baked dolomite or light-baked dolomite by holding it in an atmosphere of% or more for 1 week or longer.
本発明において、重金属類を含む焼却灰１００質量部に対する、酸化マグネシウム含有物質の量は、好ましくは１０〜５０質量部、より好ましくは１５〜４５質量部、さらに好ましくは２０質量部を超え、４０質量部以下、さらに好ましくは２１〜３５質量％、特に好ましくは２２〜３５質量部である。該量が１０質量部以上であれば、重金属類の溶出をより抑制することができる。また、固化不溶化処理後に発生する固化不溶化体の強度が過度に大きくなることを防ぐことができる。さらに、大量の焼却灰の固化不溶化処理を行う場合であっても、第二の混合工程の混合において、酸化マグネシウム含有物質が、固化不溶化体中に十分に分散されるため、酸化マグネシウム含有物質がばらつく（偏在する）ことによる重金属類の溶出抑制効果の低下がより起こりにくくなる。該量が５０質量部以下であれば、固化不溶化体のｐＨが過度に高くなる（例えば、ｐＨ１２．０以上）ことを防ぐことができる。また、固化不溶化処理後に発生する固化不溶化体の量の過度に増大することを防ぐことができる。 In the present invention, the amount of the magnesium oxide-containing substance is preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, still more preferably more than 20 parts by mass, 40 parts by mass with respect to 100 parts by mass of incinerated ash containing heavy metals. It is less than or equal to parts by mass, more preferably 21 to 35 parts by mass, and particularly preferably 22 to 35 parts by mass. When the amount is 10 parts by mass or more, elution of heavy metals can be further suppressed. In addition, it is possible to prevent the strength of the solidified insolubilized body generated after the solidified insolubilized treatment from becoming excessively high. Further, even when a large amount of incinerated ash is solidified and insolubilized, the magnesium oxide-containing substance is sufficiently dispersed in the solidified insolubilized substance in the mixing of the second mixing step, so that the magnesium oxide-containing substance is contained. The effect of suppressing the elution of heavy metals due to variation (uneven distribution) is less likely to occur. When the amount is 50 parts by mass or less, it is possible to prevent the pH of the solidified insolubilized product from becoming excessively high (for example, pH 12.0 or more). In addition, it is possible to prevent an excessive increase in the amount of the solidified insolubilized body generated after the solidified insolubilized treatment.
本発明において、鉄化合物及び酸化マグネシウム含有物質の少なくともいずれか一方の量は、焼却灰１００質量部に対して、２０質量部を超える、好ましくは２１質量部以上、より好ましくは２２質量部以上のものである。鉄化合物及び酸化マグネシウム含有物質の各々の量が、焼却灰１００質量部に対して、２０質量部以下であると、重金属類の溶出の抑制効果が低下する。特に、大量の焼却灰の固化不溶化処理を行う場合において、該抑制効果は低下する。
また、本発明において、重金属類を含む焼却灰１００質量部に対する、鉄化合物と酸化マグネシウム含有物質の合計量は、好ましくは４０質量部を超え、１００質量部以下、より好ましくは４２〜９０質量部、特に好ましくは４４〜８０質量部である。上記合計量が４０質量部を超えるものであれば、重金属類の溶出をより抑制することができる。上記合計量が１００質量部以下であれば、鉄化合物及び酸化マグネシウム含有物質にかかるコストの過度の上昇や固化不溶化処理後に発生する固化不溶化体の量の過度の増大を防ぐことができる。
また、酸化マグネシウム含有物質の量と、酸化マグネシウム含有物質及び鉄化合物の合計量の質量比（酸化マグネシウム含有物質／（酸化マグネシウム含有物質＋鉄化合物）は、重金属類の溶出をより抑制する観点から、好ましくは０．２〜０．８、より好ましくは０．２５〜０．７５、特に好ましくは０．３〜０．７である。
In the present invention, the amount of at least one of the iron compound and the magnesium oxide-containing substance exceeds 20 parts by mass, preferably 21 parts by mass or more, and more preferably 22 parts by mass or more with respect to 100 parts by mass of the incinerated ash. It is a thing. When the amounts of the iron compound and the magnesium oxide-containing substance are 20 parts by mass or less with respect to 100 parts by mass of the incinerated ash, the effect of suppressing the elution of heavy metals is reduced. In particular, when a large amount of incineration ash is solidified and insolubilized, the suppressing effect is reduced.
Further, in the present invention, the total amount of the iron compound and the magnesium oxide-containing substance is preferably more than 40 parts by mass, 100 parts by mass or less, more preferably 42 to 90 parts by mass with respect to 100 parts by mass of incinerated ash containing heavy metals. , Particularly preferably 44 to 80 parts by mass. If the total amount exceeds 40 parts by mass, the elution of heavy metals can be further suppressed. When the total amount is 100 parts by mass or less, it is possible to prevent an excessive increase in the cost of the iron compound and the magnesium oxide-containing substance and an excessive increase in the amount of the solidified insolubilized material generated after the solidified insolubilized treatment.
The mass ratio of the amount of the magnesium oxide-containing substance to the total amount of the magnesium oxide-containing substance and the iron compound (magnesium oxide-containing substance / (magnesium oxide-containing substance + iron compound) is from the viewpoint of further suppressing the elution of heavy metals. It is preferably 0.2 to 0.8, more preferably 0.25 to 0.75, and particularly preferably 0.3 to 0.7.
第二の混合工程において、鉄化合物と水を混合してなる鉄化合物水溶液と、重金属類を含む焼却灰と、酸化マグネシウム含有物質を同時に混合することで、他の混合方法（例えば、鉄化合物、水、重金属類を含む焼却灰、及び酸化マグネシウム含有物質を同時に混合する方法等）と比較して、固化不溶化体からの重金属類の溶出をより抑制することができる。
第二の混合工程における混合時間は、各材料の合計量やミキサ等の混合手段によっても異なるが、重金属類の溶出量をより小さくする観点から、好ましくは１分間以上、より好ましくは４分間以上、特に好ましくは８分間以上である。
In the second mixing step, another mixing method (for example, iron compound, for example, by simultaneously mixing an aqueous iron compound solution obtained by mixing an iron compound and water, incineration ash containing heavy metals, and a magnesium oxide-containing substance, is used. Compared with water, incineration ash containing heavy metals, and a method of simultaneously mixing a magnesium oxide-containing substance, etc.), elution of heavy metals from the solidified insolubilizer can be further suppressed.
The mixing time in the second mixing step varies depending on the total amount of each material and the mixing means such as a mixer, but from the viewpoint of reducing the elution amount of heavy metals, it is preferably 1 minute or longer, more preferably 4 minutes or longer. , Especially preferably for 8 minutes or longer.
本発明の固化不溶化体は、必要に応じて助材を含んでいてもよい。焼却灰に含まれる重金属類の種類を考慮して、適宜選択した種類及び量の助材を用いることで、重金属類等の溶出をより抑制することができる。 The solidified insolubilized body of the present invention may contain an auxiliary material, if necessary. By considering the type of heavy metals contained in the incineration ash and using an appropriately selected type and amount of auxiliary material, elution of heavy metals and the like can be further suppressed.
以下、本発明を実施例により具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
［使用材料］
（１）鉄化合物ａ：塩化第二鉄（和光純薬工業社製、濃度４０％、試薬１級）
（２）鉄化合物ｂ：塩化第一鉄（タイキ薬品工業社製、濃度３２％）
（３）鉄化合物ｃ：ポリ硫酸第二鉄（南海化学社製、Ｆｅ３＋：１１％以上）
（４）鉄化合物ｄ：硫酸第一鉄１水塩（富士チタン工業社製、商品名：ＦＤ）
（５）酸化マグネシウム含有物質ａ：軽焼マグネシア（太平洋セメント社製、酸化マグネシウムの含有率：９２質量％以上、マグネサイトを１，０００℃で３時間焼成したもの）
（６）酸化マグネシウム含有物質ｂ：ドロマイトを、電気炉を用いて７００℃で３０分間焼成した軽焼ドロマイト（酸化マグネシウムの含有率；２３質量％以上）
（７）酸化マグネシウム含有物質ｃ：海水中のマグネシウム成分から得られた水酸化マグネシウムを焼成してなる軽焼マグネシア（タテホ化学工業社製、商品名「ＴＡＴＥＨＯＭＡＧ」、酸化マグネシウムの含有率；９９質量％以上）
（８）重金属類を含む焼却灰：石炭灰１〜３
なお、表１中、酸化マグネシウム含有物質を「ＭｇＯ含有物質」、重金属類を含む焼却灰を「焼却灰」と示す。
Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.
[Material used]
(1) Iron compound a: ferric chloride (manufactured by Wako Pure Chemical Industries, Ltd., concentration 40%, reagent first grade)
(2) Iron compound b: ferrous chloride (manufactured by Taiki Yakuhin Kogyo Co., Ltd., concentration 32%)
(3) Iron compound c: Ferric polysulfate (manufactured by Nankai Chemical Co., Ltd., Fe 3+ : 11% or more)
(4) Iron compound d: ferrous sulfate monohydrate (manufactured by Fuji Titanium Industry Co., Ltd., trade name: FD)
(5) Magnesium oxide-containing substance a: Lightly fired magnesia (manufactured by Pacific Cement Co., Ltd., magnesium oxide content: 92% by mass or more, magnesite fired at 1,000 ° C. for 3 hours)
(6) Magnesium oxide-containing substance b: Light-baked dolomite obtained by calcining dolomite at 700 ° C. for 30 minutes using an electric furnace (magnesium oxide content; 23% by mass or more).
(7) Magnesium oxide-containing substance c: Light-baked magnesia (manufactured by Tateho Chemical Industries, Ltd., trade name "TATEHOMAG", magnesium oxide content; 99 mass) formed by firing magnesium hydroxide obtained from a magnesium component in seawater. %that's all)
(8) Incineration ash containing heavy metals: coal ash 1-3
In Table 1, magnesium oxide-containing substances are referred to as “MgO-containing substances”, and incineration ash containing heavy metals is referred to as “incineration ash”.
石炭灰１〜３について、表２に示す種類の重金属類の溶出量を、環境庁告示第１８号「土壌溶出量調査に係る測定方法を定める件」に記載されている方法に準拠して検液作成を行い、「ＪＩＳ Ｋ ０１０２：２０１３（工場排水試験方法）」に準拠して測定した。また、重金属類の溶出量の測定に用いられた検液のｐＨを、ｐＨメーター（堀場製作所社製、商品名「Ｆ−５２」）およびｐＨ電極（堀場製作所社製、商品名「９６１５−１０Ｄ」）を用いて測定した。
結果を表２に示す。
For coal ash 1-3, the elution amount of heavy metals of the types shown in Table 2 is inspected in accordance with the method described in Notification No. 18 of the Environment Agency "Matters for determining the measurement method for soil elution amount survey". A liquid was prepared and measured in accordance with "JIS K 0102: 2013 (factory wastewater test method)". In addition, the pH of the test solution used to measure the elution amount of heavy metals is measured by a pH meter (manufactured by HORIBA, Ltd., trade name "F-52") and a pH electrode (manufactured by HORIBA, Ltd., trade name "9615-10D"). ”) Was measured.
The results are shown in Table 2.
［実施例１〜１５］
第一の混合工程（表１中、「第一工程」と示す。）として、表１に示す種類及び配合量の鉄化合物及び水をソイルミキサーに投入した後、表１に示す時間混合して、鉄化合物水溶液を得た。
次いで、第二の混合工程（表２中、第二工程）と示す。）として、上記鉄化合物水溶液に、表１に示す種類及び配合量の、重金属類を含む焼却灰および酸化マグネシウム含有物質を投入した後、表１に示す時間混合して、固化不溶化体を得た。 得られた固化不溶化体を、２０℃の恒温室で３日間密封養生した。養生後の固化不溶化体について、表２に示す種類の重金属類の溶出量、及び、重金属類の溶出量の測定に用いられた検液のｐＨを、上記石炭灰と同様にして測定した。結果を表２に示す。
[Examples 1 to 15]
As the first mixing step (referred to as “first step” in Table 1), the iron compounds and water of the types and blending amounts shown in Table 1 are added to the soil mixer and then mixed for the time shown in Table 1. , An aqueous iron compound solution was obtained.
Next, it is shown as a second mixing step (second step in Table 2). ), Incineration ash containing heavy metals and magnesium oxide-containing substances of the types and amounts shown in Table 1 were added to the aqueous iron compound solution, and then mixed for the time shown in Table 1 to obtain a solidified insolubilized product. .. The obtained solidified insolubilized product was hermetically cured in a constant temperature room at 20 ° C. for 3 days. With respect to the solidified insolubilized material after curing, the elution amount of heavy metals of the types shown in Table 2 and the pH of the test solution used for measuring the elution amount of heavy metals were measured in the same manner as in the above coal ash. The results are shown in Table 2.
［比較例１〜２］
表１に示す種類及び量の、重金属類を含む焼却灰、酸化マグネシウム含有物質、鉄化合物、及び水をソイルミキサーに投入した後、５分間混合し、固化不溶化体を得た。
得られた固化不溶化体について、実施例１と同様にして、重金属類の溶出量、及び、検液のｐＨを測定した。
結果を表２に示す。
[Comparative Examples 1-2]
Incineration ash containing heavy metals, magnesium oxide-containing substances, iron compounds, and water of the types and amounts shown in Table 1 were added to a soil mixer and then mixed for 5 minutes to obtain a solidified insolubilized product.
With respect to the obtained solidified insolubilized material, the elution amount of heavy metals and the pH of the test solution were measured in the same manner as in Example 1.
The results are shown in Table 2.
表２から、実施例１〜５、１２〜１３と比較例１（すべての材料を同時に混合したもの）を比較すると、実施例１〜５、１２〜１３における固化不溶化体からのセレンの溶出量（０．００２〜０．００８ｍｇ／リットル）は、比較例１における固化不溶化体からのセレンの溶出量（０．０２５ｍｇ／リットル）よりも小さいことがわかる。
また、実施例６〜７と比較例２（すべての材料を同時に混合したもの）を比較すると、実施例６〜７における固化不溶化体からのひ素の溶出量（０．００１ｍｇ／リットルよりも小さい）は、比較例１における固化不溶化体からのひ素の溶出量（０．０２１ｍｇ／リットル）よりも小さいことがわかる。
さらに、実施例１〜１５における固化不溶化体からの重金属類の溶出量は、重金属類を含む焼却灰からの重金属類の溶出量よりも小さく、さらに、土壌汚染対策法における指定基準を満たしていることがわかる。
なお、土壌汚染対策法における指定基準（溶出試験）は、以下のとおりである。
セレン：０．０１ｍｇ／リットル、ひ素：０．０１ｍｇ／リットル、ホウ素：１ｍｇ／リットル、フッ素：０．８ｍｇ／リットル、六価クロム：０．０５ｍｇ／リットル
また、実施例１〜３の比較、実施例８〜９の比較、実施例１０〜１１の比較、実施例１２〜１３の比較、実施例１４〜１５の比較から、水の配合量が大きくなると、固化不溶化体からの重金属類の溶出量が小さくなることがわかる。
Comparing Examples 1 to 5, 12 to 13 and Comparative Example 1 (a mixture of all materials at the same time) from Table 2, the amount of selenium eluted from the solidified insolubilized material in Examples 1 to 5, 12 to 13. It can be seen that (0.002 to 0.008 mg / liter) is smaller than the elution amount of selenium (0.025 mg / liter) from the solidified insolubilized product in Comparative Example 1.
Comparing Examples 6 to 7 and Comparative Example 2 (a mixture of all the materials at the same time), the amount of arsenic eluted from the solidified insolubilized material in Examples 6 to 7 (smaller than 0.001 mg / liter). Is smaller than the amount of arsenic eluted from the solidified insolubilized product (0.021 mg / liter) in Comparative Example 1.
Further, the elution amount of heavy metals from the solidified insolubilized material in Examples 1 to 15 is smaller than the elution amount of heavy metals from incineration ash containing heavy metals, and further satisfies the designated criteria in the Soil Contamination Countermeasures Law. You can see that.
The designated criteria (dissolution test) in the Soil Contamination Countermeasures Law are as follows.
Selenium: 0.01 mg / liter, arsenic: 0.01 mg / liter, boron: 1 mg / liter, fluorine: 0.8 mg / liter, hexavalent chromium: 0.05 mg / liter Further, comparison and implementation of Examples 1 to 3 From the comparison of Examples 8 to 9, the comparison of Examples 10 to 11, the comparison of Examples 12 to 13, and the comparison of Examples 14 to 15, the amount of heavy metals eluted from the solidified insolubilizer increases as the amount of water blended increases. It can be seen that
Claims (3)
上記鉄化合物水溶液と、重金属類を含む焼却灰と、酸化マグネシウム含有物質を同時に混合して、固化不溶化体を得る第二の混合工程、を含む固化不溶化方法であって、
上記焼成灰１００質量部に対して、上記鉄化合物と上記酸化マグネシウム含有物質の合計量が３５〜１００質量部、上記水の量が１５〜１００質量部であり、
上記鉄化合物及び上記酸化マグネシウム含有物質の少なくともいずれか一方の量が、上記焼却灰１００質量部に対して、２０質量部を超えるものであることを特徴とする固化不溶化方法。 The first mixing step of mixing an iron compound and water to obtain an aqueous iron compound solution,
A solidification-insolubilization method comprising the second mixing step of simultaneously mixing the above-mentioned iron compound aqueous solution, incineration ash containing heavy metals, and a magnesium oxide-containing substance to obtain a solidification insolubilizer.
The total amount of the iron compound and the magnesium oxide-containing substance is 35 to 100 parts by mass, and the amount of water is 15 to 100 parts by mass with respect to 100 parts by mass of the calcined ash.
A solidification and insolubilization method, wherein the amount of at least one of the iron compound and the magnesium oxide-containing substance exceeds 20 parts by mass with respect to 100 parts by mass of the incinerated ash.
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