JP2010069391A - Decontamination method and decontaminating apparatus for contaminated soil - Google Patents
Decontamination method and decontaminating apparatus for contaminated soil Download PDFInfo
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- 238000005202 decontamination Methods 0.000 title abstract 3
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- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
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Abstract
Description
本発明は、ベンゼンなどの有機ハロゲン化合物およびシアン化合物を分離除去するとともに、六価クロム、水銀、砒素、鉛、カドミウムまたはセレン等の有害重金属、あるいはフッ素、ホウ素等の有害金属（以下、これらを総称して「重金属」という）で汚染された土壌からの重金属を分離除去する汚染土壌の浄化方法および浄化装置に関する。 The present invention separates and removes organic halogen compounds such as benzene and cyanide compounds, and harmful heavy metals such as hexavalent chromium, mercury, arsenic, lead, cadmium and selenium, or harmful metals such as fluorine and boron (hereinafter referred to as these). The present invention relates to a method and an apparatus for purifying contaminated soil that separates and removes heavy metals from soil contaminated with “heavy metal”.
近年、環境に対する関心が高まり法的整備が行なわれ産業活動も環境への配慮が求められるようになった。しかしながら、過去において環境への十分な配慮なしに行われた産業活動の結果、当該産業の跡地には、しばしば、人体に有害な物質で汚染された土壌が残されていることがある。例えば、都市ガス工場跡地では、石炭を原料として都市ガスの製造を行った際、石炭に含有されていた有害物質、製造工程で生成されたものが石炭炉のあった場所に蓄積されたりして、土壌が汚染されていることが多い。具体的な汚染物質としては、ベンゼン、シアン化合物、ひ素、鉛、水銀、六価クロム、カドミウムなどが想定される。このように汚染物質を含む土壌で覆われた工場跡地などを再開発するにあたっては、汚染された土壌のままでは新規事業用途への土地再開発ができないので、汚染土壌の対策が必要になる。 In recent years, interest in the environment has increased, legal development has been carried out, and industrial activities have come to require consideration for the environment. However, as a result of industrial activities carried out in the past without sufficient consideration for the environment, soils contaminated with substances harmful to human bodies are often left in the former site of the industry. For example, at the city gas factory site, when city gas is produced using coal as a raw material, harmful substances contained in the coal and those produced in the production process are accumulated in the place where the coal furnace was located. Often, the soil is contaminated. Specific pollutants include benzene, cyanide, arsenic, lead, mercury, hexavalent chromium and cadmium. When redeveloping a factory site covered with soil containing pollutants in this way, it is necessary to take measures against contaminated soil because the redevelopment of land for new business use cannot be made with contaminated soil.
これら汚染物質には、人の健康を保護し、生活環境を保全する上で維持されることが望ましいとされる環境基準が設けられており、土壌１ｋｇあたりの含有量基準でいえば、カドミウム、鉛、砒素は１５０ｍｇ以下、六価クロムは２５０ｍｇ以下、水銀は１５ｍｇ以下、フッ素およびほう素は４０００ｍｇ以下である。また、ダイオキシン類は、土壌１ｇに対し、１０００ｐｇ−ＴＥＱ（毒性等価量）以下である。 These pollutants are provided with environmental standards that are desirable to protect human health and preserve the living environment. The content standards per kg of soil are cadmium, Lead and arsenic are 150 mg or less, hexavalent chromium is 250 mg or less, mercury is 15 mg or less, and fluorine and boron are 4000 mg or less. Moreover, dioxins are below 1000pg-TEQ (toxic equivalent amount) with respect to 1g of soil.
このように産業廃液などにより汚染された土壌から汚染物質を分解除去する方法として、先ず、熱による方法がある。例えば特許文献１に示すように、掘り出された汚染土壌を予備乾燥した後、８００〜１０００℃ の温度で加熱して有害物質を気相に移行させ、当該有害物質を含んだ排ガスをサイクロンで粉塵を除去し、こうして粉塵が除去された排ガスを二次燃焼させるという土壌処理方法が記載されている。 As a method for decomposing and removing pollutants from soil contaminated with industrial waste liquid or the like, there is a method using heat. For example, as shown in Patent Document 1, after excavated contaminated soil is preliminarily dried, it is heated at a temperature of 800 to 1000 ° C. to transfer the harmful substance to the gas phase, and the exhaust gas containing the harmful substance is removed with a cyclone. A soil treatment method is described in which dust is removed and the exhaust gas from which the dust is thus removed is subjected to secondary combustion.
また、特許文献２には、揮発性有機物質を含む土壌にキャリアー空気を供給しつつ当該土壌を間接加熱方式で加熱し、加熱する温度をその揮発物質の沸点を超える温度にすることが記載され、上記沸点＋５０℃以内が望ましいと記載されている。また、特許文献３では、汚染物質を採掘し、篩い分けし、油汚染された土壌では回転式加熱炉にて２５０℃以上の温度で５分加熱する方法が、シアン化合物では３００℃以上の温度で５分以上加熱する方法が提案されている。これは全て、熱源としてガス、油などの燃焼または電気ヒータを用いることとなるが、エネルギーの多用は炭酸ガスの発生につながるため環境対策の観点から好ましくない。これに対し、熱源になるとともに、対象物質に対して選択的に作用するマイクロ波をアプリケータを被せた汚染土壌に照射して汚染土壌を昇温して汚染土壌の無害化を図ることが特許文献４に記載されている。
Patent Document 2 describes that the soil is heated by an indirect heating method while supplying carrier air to the soil containing the volatile organic substance, and the heating temperature is set to a temperature exceeding the boiling point of the volatile substance. The above boiling point + 50 ° C. is desirable. Further, in
また、浄化剤を用いた例として、特許文献５には、金属鉄− マグネタイト混合粒子による有機ハロゲン化合物の分解処理が紹介されている。これは、発明者によれば、金属鉄−マグネタイト混合粒子中の金属鉄粒子が、金属鉄粒子と水との反応によって活性水素を生成させ、生成した活性水素によって近傍にあるマグネタイト粒子表面を還元して、活性化し、生成した活性水素の一部は、金属鉄粒子表面に吸着した有機ハロゲン化合物を水素化脱ハロゲンして無害化する一方、活性化したマグネタイト粒子は粒子表面に吸着した有機ハロゲン化合物に対し水素化脱ハロゲン反応を進行させ無害化するものと説明されている。 Further, as an example using a purifying agent, Patent Document 5 introduces a decomposition treatment of an organic halogen compound with metallic iron-magnetite mixed particles. According to the inventors, the metal iron particles in the metal iron-magnetite mixed particles generate active hydrogen by the reaction between the metal iron particles and water, and reduce the nearby magnetite particle surface by the generated active hydrogen. Then, a part of the activated active hydrogen generated and activated is detoxified by hydrodehalogenating the organic halogen compound adsorbed on the surface of the metal iron particles, while the activated magnetite particles are adsorbed on the surface of the particle. It is described that a compound undergoes a hydrodehalogenation reaction to make it harmless.
上記の汚染土壌対策は、いずれも、有機化合物に対しては有効であるが、土壌汚染対策法施行規則で第二種特定有害物質に分類される、カドミウム、水銀、鉛、六価クロムなどの重金属の対策には上記とは異なる方法が提案されている。例えば、特許文献６には、ポルトランドセメント、高炉スラグ、石膏を含むセメント系処理剤を混合・攪拌することで、汚染土壌を固化不溶化することが開示されている。
上記に説明した従来の汚染土壌対策は、汚染物質に応じて対応が取られていてそれぞれ最適化されているが統一的な方法が存在しないことが分かる。また熱を用いる方法では、炭酸ガスの発生を抑えるという環境への配慮も必要であり、省エネ化を図ることも求められる。さらに、汚染土壌を処分場へ移動しての処分は、汚染土壌の移動に伴う費用が掛かるとともに汚染物質の所在地を変更するだけのメリーゴーランド現象を招くおそれもあるので、汚染土壌のある現場での処分が望ましい。 It can be seen that the conventional countermeasures against contaminated soil described above are taken according to the pollutants and optimized respectively, but there is no unified method. In addition, in the method using heat, it is necessary to consider the environment to suppress the generation of carbon dioxide, and energy saving is also required. In addition, disposal of contaminated soil to a disposal site is costly with the movement of contaminated soil and may cause a merry-go-round phenomenon that only changes the location of the contaminant. Disposal is desirable.
上記課題を解決するべく、本発明は省エネルギーを考慮した汚染物質の種類によらない統一的な汚染土壌の浄化方法および浄化装置を提供すること、併せて、環境負荷の少ない汚染土壌の浄化方法および浄化装置を提供することを目的とする。 In order to solve the above-mentioned problems, the present invention provides a unified contaminated soil purification method and purification device that does not depend on the type of pollutant in consideration of energy saving. An object is to provide a purification device.
上記課題を解決するために、発明者は鋭意研究を重ねた結果、省エネルギーの観点から熱源としてマイクロ波の優位性に着目し、マイクロ波に強く反応して昇温するマグネタイトを汚染土壌に混ぜて、マイクロ波を照射することが大変有効なことを見出した。さらに、マグネタイトに水素を反応させて得た酸素欠陥マグネタイトと炭酸ガスを反応させてマグネタイトの表面に炭素を析出させた炭素付着活性化マグネタイトが、マイクロ波の照射と組み合わせることで熱源としても、還元剤としても大変有効なことを見出した。
以下に、本発明の内容を説明する。
In order to solve the above-mentioned problems, the inventor has conducted intensive research and has focused on the superiority of microwaves as a heat source from the viewpoint of energy saving, and mixed magnetite that reacts strongly with microwaves and raises temperature to contaminated soil. It was found that irradiation with microwaves was very effective. In addition, carbon-attached activated magnetite, in which carbon is deposited on the surface of magnetite by reacting oxygen-deficient magnetite obtained by reacting hydrogen with magnetite and carbon dioxide, can be reduced as a heat source by combining with microwave irradiation. It was found to be very effective as an agent.
The contents of the present invention will be described below.
請求項１に記載された発明は、有毒な物質により汚染された汚染土壌に、マグネタイトを混ぜ、マイクロ波を照射することを特徴とする汚染土壌の浄化方法である。マグネタイトはマイクロ波を有効に吸収して発熱し周囲の汚染土壌の温度を上昇させる。 The invention described in claim 1 is a method for purifying contaminated soil, characterized in that magnetite is mixed in contaminated soil contaminated with a toxic substance and irradiated with microwaves. Magnetite effectively absorbs microwaves and generates heat, raising the temperature of the surrounding contaminated soil.
請求項２に記載された発明は、前記マグネタイトが、マグネタイトの表面に炭素の付着した炭素付着マグネタイトであることを特徴とする請求項１に記載の汚染土壌の浄化方法である。マイクロ波を吸収することで温度の上昇した炭素は常温時にくらべさらに活性化して汚染物質を還元するとともに自らも酸化燃焼して周囲の温度を更に上昇させる。 The invention described in claim 2 is the method for purifying contaminated soil according to claim 1, wherein the magnetite is carbon-attached magnetite in which carbon is attached to the surface of magnetite. By absorbing microwaves, the carbon that has risen in temperature is more activated than normal temperature to reduce pollutants and oxidize and burn itself to further raise the ambient temperature.
請求項３に記載された発明は、前記炭素付着マグネタイトが、マグネタイトに水素を反応させて得た酸素欠陥マグネタイトに、さらに炭酸ガスを反応させてマグネタイトの表面に炭素を生成した炭素付着活性化マグネタイトであることを特徴とする請求項２に記載の汚染土壌の浄化方法である。酸素欠陥マグネタイトの表面で還元された炭酸ガスから生成される活性度の高い炭素は周辺の重金属などと化合物を生成する。 According to a third aspect of the present invention, there is provided the carbon-attached activated magnetite in which the carbon-attached magnetite is produced by reacting carbon deficient gas with oxygen-deficient magnetite obtained by reacting hydrogen with magnetite, and generating carbon on the surface of the magnetite The method for purifying contaminated soil according to claim 2, wherein: Highly active carbon produced from carbon dioxide gas reduced on the surface of oxygen-deficient magnetite produces compounds such as surrounding heavy metals.
請求項４に記載された発明は、前記汚染土壌が攪拌されながらマイクロ波を照射されることを特徴とする請求項1乃至３いずれか1項に記載の汚染土壌の浄化方法である。汚染土壌中に分散したマイクロ波を照射されて昇温しているマグネタイトは汚染土壌とともに攪拌されることで満遍なく汚染土壌に接触して汚染物質を包摂する。 The invention described in claim 4 is the method for purifying contaminated soil according to any one of claims 1 to 3, wherein the contaminated soil is irradiated with microwaves while being agitated. Magnetite heated by being irradiated with microwaves dispersed in the contaminated soil is stirred together with the contaminated soil and uniformly contacts the contaminated soil to include the contaminant.
請求項５に記載された発明は、マイクロ波の照射により温度が上昇する汚染土壌の処理温度が、揮発性有機物が気化する温度帯と、重金属がマグネタイトに包摂される温度帯とに分けられて汚染土壌が処理されることを特徴とする請求項1乃至４いずれか1項に記載の汚染土壌の浄化方法である。主に、揮発性有機物質と重金属で汚染された土壌は、まず、マイクロ波の照射により揮発性有機物が気化する温度帯に保たれて揮発性有機物が気化されて回収され、さらに、その後の汚染土壌へのマイクロ波照射により汚染土壌はさらに昇温されてマグネタイトに重金属が包摂される温度帯で重金属が処理される。 In the invention described in claim 5, the treatment temperature of the contaminated soil whose temperature rises due to microwave irradiation is divided into a temperature zone where volatile organic substances are vaporized and a temperature zone where heavy metals are included in magnetite. The method for purifying contaminated soil according to any one of claims 1 to 4, wherein the contaminated soil is treated. Mainly, soil contaminated with volatile organic substances and heavy metals is first kept in a temperature zone where volatile organic substances are vaporized by microwave irradiation, and volatile organic substances are vaporized and recovered. The contaminated soil is further heated by microwave irradiation to the soil, and the heavy metal is treated in a temperature range in which the heavy metal is included in the magnetite.
請求項６に記載された発明は、重金属を包摂したマグネタイトを磁気的に分離回収することを特徴とする請求項1乃至５いずれか1項に記載の汚染土壌の浄化方法である。重金属を包摂したマグネタイトは磁場に反応するので容易に磁気的に分離されて回収される。 The invention described in claim 6 is the method for purifying contaminated soil according to any one of claims 1 to 5, wherein magnetite including heavy metal is magnetically separated and recovered. Magnetite containing heavy metal reacts with a magnetic field and is easily magnetically separated and recovered.
請求項７に記載された発明は、請求項1乃至６いずれか1項に記載の汚染土壌の浄化方法を用いる汚染土壌の浄化装置である。請求項1乃至６に記載の汚染土壌の浄化方法は比較的小型の装置として稼動させることが可能であり、汚染土壌を他所へ移動させずに、その場所に浄化装置を設けて汚染土壌の浄化を行うことができる。 The invention described in claim 7 is a contaminated soil purification apparatus using the method for purifying contaminated soil according to any one of claims 1 to 6. The method for purifying contaminated soil according to any one of claims 1 to 6 can be operated as a relatively small device, and the contaminated soil is purified by providing a purification device at the place without moving the contaminated soil to another place. It can be performed.
請求項１に記載された発明によれば、有毒な物質により汚染された汚染土壌に、マグネタイトを混ぜ、マイクロ波を照射するので、マイクロ波に選択的に反応するマグネタイトが効率的に昇温され周囲の汚染土壌を昇温し、汚染土壌中の揮発性有機物質が気化されて汚染土壌から放出され、さらに昇温された汚染土壌の重金属がマグネタイトに包摂されてマグネタイトに固定され取り込まれる。気化した揮発性有機物質およびマグネタイトに包摂された重金属はそれぞれ汚染土壌から容易に分離することができるので、請求項１に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 According to the invention described in claim 1, since magnetite is mixed with the contaminated soil contaminated with the toxic substance and irradiated with the microwave, the magnetite that selectively reacts with the microwave is efficiently heated. The surrounding contaminated soil is heated, the volatile organic substances in the contaminated soil are vaporized and released from the contaminated soil, and the heavy metal of the heated contaminated soil is included in the magnetite, fixed to the magnetite and taken in. Since the vaporized volatile organic substance and the heavy metal encapsulated in the magnetite can be easily separated from the contaminated soil, respectively, the invention described in claim 1 can be used to purify the contaminated soil with low cost and high thermal efficiency and low environmental load. A method can be provided.
請求項２に記載された発明によれば、前記マグネタイトが、マグネタイトの表面に炭素の付着した炭素付着マグネタイトであるので、マグネタイトおよび炭素がマイクロ波を吸収して昇温するとともに炭素は自らも酸化燃焼して周囲の温度を更に上昇させることで汚染土壌の昇温が効率的に行われる。また温度の上昇した炭素は常温時にくらべ活性化して汚染物質を還元するとともにマグネタイトへの汚染物質の包摂をより効率的に行う。したがって、汚染土壌中の揮発性有機物質の気化による汚染土壌からの放出と、さらに昇温された汚染土壌の重金属がマグネタイトに包摂されてマグネタイトに固定される取り込みがより効率的に行なわれる。気化した揮発性有機物質およびマグネタイトに包摂された重金属はそれぞれ汚染土壌から容易に分離することができるので、請求項２に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 According to the second aspect of the present invention, since the magnetite is a carbon-attached magnetite in which carbon is attached to the surface of the magnetite, the temperature of the magnetite and carbon is increased by absorbing the microwave and the carbon itself is oxidized. By raising the ambient temperature further by burning, the temperature of the contaminated soil is efficiently increased. Carbon at an elevated temperature is activated at room temperature to reduce pollutants and more efficiently contain pollutants in magnetite. Therefore, the release from the contaminated soil due to the vaporization of the volatile organic substances in the contaminated soil, and the uptake of the heavy metal of the heated contaminated soil being included in the magnetite and fixed to the magnetite are performed more efficiently. Since the vaporized volatile organic substance and the heavy metal encapsulated in the magnetite can be easily separated from the contaminated soil, respectively, the invention described in claim 2 purifies the contaminated soil with low cost and high thermal efficiency and low environmental load. A method can be provided.
請求項３に記載された発明によれば、前記炭素付着マグネタイトが、マグネタイトに水素を反応させて得た酸素欠陥マグネタイトに、さらに炭酸ガスを反応させて、マグネタイトの表面に炭素を生成した炭素付着活性化マグネタイトであるので、活性度の高いマグネタイトに付着した炭素は周辺の重金属などと容易に化合物を生成してマグネタイトに重金属を固定する。マグネタイトに固定された重金属は汚染土壌から容易に分離することができるので、請求項３に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。
According to the invention described in
請求項４に記載された発明によれば、前記汚染土壌が攪拌されながらマイクロ波を照射されるので、汚染土壌中に分散したマグネタイトは汚染土壌とともに攪拌されることで満遍なく汚染土壌にへの接触が促進され、昇温している汚染物質を効果的に包摂する。マグネタイトに固定された重金属は汚染土壌から容易に分離することができるので、請求項４に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 According to the invention described in claim 4, since the contaminated soil is irradiated with microwaves while being agitated, the magnetite dispersed in the contaminated soil is evenly contacted with the contaminated soil by being agitated together with the contaminated soil. Is effectively promoted and effectively includes the pollutants that are heated. Since the heavy metal fixed to the magnetite can be easily separated from the contaminated soil, the invention described in claim 4 can provide a method for purifying the contaminated soil at a low cost and with high thermal efficiency and low environmental load.
請求項５に記載された発明によれば、マイクロ波の照射に伴う汚染土壌の上昇温度が、揮発性有機物が気化する温度帯と、重金属がマグネタイトに包摂される温度帯とに分けられて処理されるので、揮発性有機物質と重金属で汚染された土壌は、まず、揮発性有機物が気化する温度帯に保たれて揮発性有機物が気化されて回収され、その後の汚染土壌へのマイクロ波照射により汚染土壌はさらに昇温されて、マグネタイトに重金属が包摂される温度帯で重金属が処理されることとなり、請求項５に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 According to the invention described in claim 5, the rising temperature of the contaminated soil accompanying microwave irradiation is divided into a temperature zone where volatile organic substances are vaporized and a temperature zone where heavy metals are included in magnetite. Therefore, soil contaminated with volatile organic substances and heavy metals is first maintained at a temperature range where volatile organic substances are vaporized, and volatile organic substances are vaporized and recovered, and then microwave irradiation is applied to the contaminated soil. As a result, the contaminated soil is further heated, and the heavy metal is processed in a temperature range in which the heavy metal is included in the magnetite. According to the invention described in claim 5, the contaminated soil with low environmental impact and high thermal efficiency is obtained. A purification method can be provided.
請求項６に記載された発明によれば、重金属を包摂したマグネタイトを磁気的に分離回収するので、磁場に反応するマグネタイトに包摂された重金属がマグネタイトともに容易に磁気的に分離されて回収され、重金属を資源として再利用することで経済性を高めることもできることから、請求項６に記載された発明によって、経済性の高い熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 According to the invention described in claim 6, since the magnetite enclosing the heavy metal is magnetically separated and recovered, the heavy metal included in the magnetite that reacts to the magnetic field is easily magnetically separated and recovered together with the magnetite. Since it is possible to improve economy by reusing heavy metal as a resource, the invention described in claim 6 can provide a method for purifying contaminated soil with high economic efficiency and high environmental efficiency and low environmental load. .
請求項７に記載された発明によれば、請求項1乃至６いずれか1項に記載の汚染土壌の浄化方法を用いる汚染土壌の浄化装置であるので、前記の汚染土壌の浄化方法の原理が簡単であることから、請求項７に記載された発明によって、比較的小型の土壌浄化装置として稼動させることが可能であり、汚染土壌を他所へ移動させずに、その場所に浄化装置を設けて汚染土壌の浄化を行うことができるという大きな効果を奏する。 According to the invention described in claim 7, since it is a contaminated soil purification apparatus using the method for purifying contaminated soil according to any one of claims 1 to 6, the principle of the method for purifying contaminated soil is as follows. Since it is simple, it can be operated as a relatively small soil purification device by the invention described in claim 7, and the purification device is provided at that place without moving the contaminated soil to another place. It has a great effect that the contaminated soil can be purified.
本発明の汚染土壌の浄化方法は、図1の原理図に示すように、有毒な物質により汚染された汚染土壌に、マグネタイトを混ぜ、マイクロ波を照射することが特徴である。マイクロ波による加熱は、過熱時間が短い、均一な加熱が可能である、熱効率が高い、加熱時の温度制御が容易などの特徴がある。マイクロ波の周波数は問わないが、マイクロ波源として入手しやすいマグネトロンを使い、周波数2.45GHZ付近が好ましい。このマイクロ波加熱の特徴を最大限に引き出すには、マイクロ波に選択的に反応するマグネタイトを汚染土壌中に混ぜ込んで充分に分散させて、マイクロ波照射を行なうことが好ましい。汚染土壌中に分散したマグネタイトは、照射されたマイクロ波に選択的に反応して温度が上昇する。周囲の土壌も土壌中の水分がマイクロ波に反応して温度が上昇するが、マグネタイトは効率的に昇温するのでマグネタイトの周辺は特に温度上昇が大きくなる。マグネタイトが周囲環境と反応するためには比表面積を大きくすることが好ましいのでマグネタイトの粒径は小さいことが好ましい。具体的には、0.5μm〜1.1μmが好ましい。比表面積を増やすには中空形状のマグネタイトを用いることもできる。中空形状のマグネタイトは、加水分解性鉄塩の水溶液中にコアとなる、粒子径が０．０１〜１４０μmの球状重合体を分散せしめ、加水分解反応により該球状重合体粒子上に酸化鉄層をもうけ、球状重合体−酸化鉄複合粒子を得、さらに、上記球状重合体−酸化 鉄複合粒子を水素雰囲気下、例えば１５０℃以上、好ましくは２５０℃以上、または空気中、例えば１５０℃以上、好ましくは３００℃以上で処理しさらに必要 に応じ還元し、部分的に還元することにより、球状マグネタイト中空粒子を得ることができる。また、コアとなる粒子径が０．０１〜１４０μm の不飽和芳香族類、ビニルエステル類などからなる球状重合体粒子とシェルとなる粒子径がその１／５以下である酸化鉄粒子を気流中で高速攪拌することにより球状重合体−酸化鉄複合粒子を得、次いで上記と 同様の熱処理操作によりマグネタイト中空粒子を得る。上記で得られたマグネタイト中空粒子の粒子径は０．０１〜１５０μm であり、粒子径に対する内部空孔径の比は０．３〜０．９５である。 As shown in the principle diagram of FIG. 1, the method for purifying contaminated soil of the present invention is characterized by mixing magnetite and irradiating microwaves to contaminated soil contaminated with a toxic substance. Microwave heating has features such as a short overheating time, uniform heating, high thermal efficiency, and easy temperature control during heating. The frequency of the microwave is not limited, but a magnetron that is easily available as a microwave source is used, and a frequency around 2.45 GHz is preferable. In order to maximize the characteristics of the microwave heating, it is preferable to perform microwave irradiation by mixing magnetite that selectively reacts with microwaves into the contaminated soil and sufficiently dispersing it. The magnetite dispersed in the contaminated soil selectively reacts with the irradiated microwave and the temperature rises. The surrounding soil also rises in temperature due to the moisture in the soil reacting to the microwave, but the temperature rises particularly in the vicinity of the magnetite because the temperature rises efficiently. In order for magnetite to react with the surrounding environment, it is preferable to increase the specific surface area, so that the particle size of magnetite is preferably small. Specifically, 0.5 μm to 1.1 μm is preferable. In order to increase the specific surface area, hollow magnetite can also be used. The hollow-shaped magnetite is obtained by dispersing a spherical polymer having a particle size of 0.01 to 140 μm as a core in an aqueous solution of a hydrolyzable iron salt, and forming an iron oxide layer on the spherical polymer particles by a hydrolysis reaction. Further, spherical polymer-iron oxide composite particles are obtained, and the spherical polymer-iron oxide composite particles are further obtained in a hydrogen atmosphere, for example, 150 ° C or higher, preferably 250 ° C or higher, or in air, for example, 150 ° C or higher, preferably The spherical magnetite hollow particles can be obtained by treating at 300 ° C. or higher, further reducing if necessary, and partially reducing. In addition, spherical polymer particles made of unsaturated aromatics, vinyl esters, etc. having a core particle size of 0.01 to 140 μm and iron oxide particles having a shell particle size of 1/5 or less in the air stream. Then, spherical polymer-iron oxide composite particles are obtained by stirring at a high speed, and then magnetite hollow particles are obtained by the same heat treatment operation as described above. The particle diameter of the magnetite hollow particles obtained above is 0.01 to 150 μm, and the ratio of the internal pore diameter to the particle diameter is 0.3 to 0.95.
また、マグネタイトを無機系多孔質粒子の表面に付着したものも反応性が高いので好ましい。表面にマグネタイトを付着した無機系多孔質粒子を得るには、鉄塩溶液中に無機系多孔質粒子を浸漬する浸漬工程と、前記浸漬工程を経た後、無機系多孔質粒子を焼成する焼成工程を用いる。 Also, magnetite attached to the surface of inorganic porous particles is preferable because of its high reactivity. In order to obtain inorganic porous particles having magnetite attached to the surface, an immersion step of immersing the inorganic porous particles in an iron salt solution, and a firing step of firing the inorganic porous particles after the immersion step Is used.
上記いずれのマグネタイトであっても、また、他の形態のマグネタイトであっても、汚染土壌中のマグネタイトはマイクロ波を照射されると、マグネタイトがマイクロ波に選択的に反応するので、マグネタイトが効率的に昇温され周囲の汚染土壌を昇温し、汚染土壌中の揮発性有機物質が気化されて汚染土壌から放出され、さらに昇温された汚染土壌の重金属がマグネタイトに包摂されてマグネタイトに固定され取り込まれる。気化した揮発性有機物質およびマグネタイトに包摂された重金属はそれぞれ汚染土壌から容易に分離することができることから、請求項１に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 Regardless of the magnetite mentioned above, or any other form of magnetite, the magnetite in the contaminated soil will react selectively with the microwave when irradiated with microwave, so the magnetite is efficient. The temperature of the contaminated soil is raised and the surrounding volatile organic substances are vaporized and released from the contaminated soil, and the heavy metals of the heated contaminated soil are included in the magnetite and fixed to the magnetite. And captured. Since the vaporized volatile organic substance and the heavy metal contained in the magnetite can be easily separated from the contaminated soil, respectively, the invention described in claim 1 can be used to purify the contaminated soil at a low cost and with high thermal efficiency and low environmental load. A method can be provided.
本発明の汚染土壌の浄化方法においては、前記マグネタイトがマグネタイトの表面に炭素の付着した炭素付着マグネタイトであることが好ましい。マグネタイトの表面に炭素を付着させるには炭素粉末とマグネタイト粉末を攪拌する物理的な方法とマグネタイトの表面に炭素化合物を付着させてから炭素化合物を還元処理するという化学的な方法でもよい。 In the method for purifying contaminated soil of the present invention, the magnetite is preferably carbon-adhered magnetite in which carbon is attached to the surface of magnetite. Carbon may be attached to the surface of the magnetite by a physical method of stirring the carbon powder and the magnetite powder or a chemical method of reducing the carbon compound after attaching the carbon compound to the surface of the magnetite.
マグネタイトの空孔内を含む表面に炭素が付着した炭素付着マグネタイトにおいては、マグネタイトおよび炭素がマイクロ波を吸収して昇温するとともに炭素は自らも酸化燃焼して周囲の温度を更に上昇させることで汚染土壌の昇温が効率的に行われる。また温度の上昇した炭素は常温時にくらべ活性化して汚染物質を還元するとともにマグネタイトへの汚染物質の包摂をより効率的に行う。したがって、汚染土壌中の揮発性有機物質の気化による汚染土壌からの放出と、さらに昇温された汚染土壌の重金属がマグネタイトに包摂されてマグネタイトに固定される取り込みがより効率的に行なわれる。気化した揮発性有機物質およびマグネタイトに包摂された重金属はそれぞれ汚染土壌から容易に分離することができるので、請求項２に記載された発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 In the carbon-attached magnetite where carbon is attached to the surface including the inside of the magnetite vacancy, the temperature of the magnetite and carbon absorbs microwaves, and the carbon itself oxidizes and burns to raise the ambient temperature further. The temperature of the contaminated soil is efficiently increased. Carbon at an elevated temperature is activated at room temperature to reduce pollutants and more efficiently contain pollutants in magnetite. Therefore, the release from the contaminated soil due to the vaporization of the volatile organic substances in the contaminated soil, and the uptake of the heavy metal of the heated contaminated soil being included in the magnetite and fixed to the magnetite are performed more efficiently. Since the vaporized volatile organic substance and the heavy metal encapsulated in the magnetite can be easily separated from the contaminated soil, respectively, the invention described in claim 2 purifies the contaminated soil with low cost and high thermal efficiency and low environmental load. A method can be provided.
本発明の汚染土壌の浄化方法においては、前記炭素付着マグネタイトが、マグネタイトに水素を反応させて得た酸素欠陥マグネタイトに炭酸ガスを反応させて、マグネタイトの表面に炭素を生成した炭素付着活性化マグネタイトであることが好ましい。炭素付着活性化マグネタイトは、以下の方法で得られる。先ず、湿式法により合成したマグネタイト（１〜５ｇ：粒径１００〜２００ｎｍ）を反応セル内に入れ、水素ガスを１〜４時間、２８０〜３００℃で通じると、反応セル内にマグネタイト中の格子酸素が水となって除去されて活性化する。マグネタイトは結晶学的に、スピネル型構造を有し、酸素が立方最密充填しており、その隙間（Ａｓｉｔｅ，Ｂｓｉｔｅ）に、Ｆｅ2+ ，Ｆｅ3+ が１：２の割合で詰まっているこのマグネタイトは３００℃付近で水素ガスを通じることによって、スピネル構造中の酸素イオンが抜けてＦｅ3 Ｏ4- δで示される酸素欠陥マグネタイトに代わるものと推定される。その後、３５０℃でＣＯ2 と反応させ、表面にＣを生成させることにより炭素付着活性化マグネタイトを得られる。 In the method for purifying contaminated soil according to the present invention, the carbon-attached magnetite is a carbon-attached activated magnetite that generates carbon on the surface of magnetite by reacting carbon dioxide with oxygen-deficient magnetite obtained by reacting hydrogen with magnetite. It is preferable that Carbon adhesion activated magnetite is obtained by the following method. First, magnetite (1-5 g: particle size 100-200 nm) synthesized by a wet method is put in a reaction cell, and hydrogen gas is passed at 280-300 ° C. for 1-4 hours. Oxygen is removed as water and activated. Magnetite has a spinel structure crystallographically, oxygen is closely packed in cubic, and the gaps (Asite, Bsite) are filled with Fe2 + and Fe3 + at a ratio of 1: 2, 300 It is presumed that oxygen ions in the spinel structure are removed by passing hydrogen gas at around 0 ° C., replacing oxygen-deficient magnetite represented by Fe3 O4-δ. Thereafter, the carbon adhesion activated magnetite is obtained by reacting with CO2 at 350 DEG C. to produce C on the surface.
マグネタイトに付着した活性度の高い炭素は周辺の重金属などと容易に化合物を生成してマグネタイトに重金属を固定する。マグネタイトに固定された重金属は汚染土壌から容易に分離することができるので、本発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 Carbon with high activity attached to magnetite easily forms a compound with surrounding heavy metals and fixes heavy metals to magnetite. Since the heavy metal fixed to the magnetite can be easily separated from the contaminated soil, the present invention can provide a method for purifying the contaminated soil at a low cost and with high thermal efficiency and low environmental load.
本発明の汚染土壌の浄化方法においては、前記汚染土壌が攪拌されながらマイクロ波を照射されることが好ましい。攪拌とマイクロ波照射を時間を分けてバッチ処理することもできるが、作業の効率を考えると、前記汚染土壌が攪拌されながらマイクロ波を照射されることが好ましい。汚染土壌中に分散したマグネタイトは汚染土壌とともに攪拌されることで満遍なく汚染土壌にへの接触が促進され、昇温している汚染物質を効果的に包摂する。マグネタイトに固定された重金属は汚染土壌から容易に分離することができるので、本発明によって、安価で熱効率の高い環境負荷の少ない効率的な汚染土壌の浄化方法を提供することができる。 In the contaminated soil purification method of the present invention, it is preferable that the contaminated soil is irradiated with microwaves while being agitated. Stirring and microwave irradiation can be batch-processed by dividing the time, but considering the efficiency of work, it is preferable that the contaminated soil is irradiated with microwaves while stirring. The magnetite dispersed in the contaminated soil is stirred together with the contaminated soil, so that the contact with the contaminated soil is promoted uniformly, and the pollutants whose temperature is increased are effectively included. Since the heavy metal fixed to the magnetite can be easily separated from the contaminated soil, the present invention can provide an efficient method for purifying the contaminated soil at a low cost and with high thermal efficiency and low environmental load.
本発明の汚染土壌の浄化方法においては、マイクロ波の照射に伴う汚染土壌の上昇温度が、揮発性有機物が気化する温度帯と、重金属がマグネタイトに包摂される温度帯とに分けられて処理されることが好ましい。図２に模式的に示すように、汚染土壌の入った各キルンをそれぞれのマイクロ波源により供給されるマイクロ波を照射して温度の上昇を図る。汚染土壌をキルンで揮発性有機物質と重金属で汚染された土壌は、まず、揮発性有機物が気化する温度帯、具体的には80度C〜100度C程度に保たれて揮発性有機物が気化されて回収され、その後の汚染土壌へのマイクロ波照射により汚染土壌はさらに昇温されて、温度６００度C〜７００度Cで、鉛、カドミウム、砒素などの低融点金属がマグネタイトに包摂され、温度９００度C〜１３００度Cでニッケル、マンガンなどがの重金属がマグネタイトに包摂されて処理され、マグネタイトに包摂された重金属は容易に汚染土壌から分離されることとなり、本発明によって、安価で熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 In the method for purifying contaminated soil of the present invention, the rising temperature of the contaminated soil due to microwave irradiation is divided into a temperature range where volatile organic substances are vaporized and a temperature range where heavy metals are included in magnetite. It is preferable. As schematically shown in FIG. 2, each kiln containing contaminated soil is irradiated with microwaves supplied from the respective microwave sources to increase the temperature. The soil contaminated with volatile organic substances and heavy metals in the kiln is first kept in a temperature range where volatile organic substances are vaporized, specifically about 80 degrees C to 100 degrees C, and volatile organic substances are vaporized. Then, the contaminated soil is further heated by microwave irradiation to the contaminated soil, and a low melting point metal such as lead, cadmium, and arsenic is included in the magnetite at a temperature of 600 ° C to 700 ° C. Heavy metals such as nickel and manganese are included in the magnetite and processed at a temperature of 900 ° C. to 1300 ° C., and the heavy metal included in the magnetite is easily separated from the contaminated soil. It is possible to provide a purification method for contaminated soil with a high environmental load and a low environmental impact.
本発明の汚染土壌の浄化方法においては、重金属を包摂したマグネタイトを磁気的に分離回収することが好ましい。図３にイメージ図で示すように、マグネタイトに包摂された重金属は磁場に反応するマグネタイトとともに磁石を用いて容易に磁気的に分離されて回収され、重金属を資源として再利用することで経済性を高めることもできることから、本発明によって、経済性の高い熱効率の高い環境負荷の少ない汚染土壌の浄化方法を提供することができる。 In the method for purifying contaminated soil of the present invention, it is preferable to magnetically separate and recover magnetite including heavy metals. As shown in the image diagram in FIG. 3, the heavy metal included in the magnetite is easily separated magnetically using a magnet together with the magnetite that reacts to the magnetic field and recovered, and the economy is improved by reusing the heavy metal as a resource. Therefore, according to the present invention, it is possible to provide a method for purifying contaminated soil with high economic efficiency, high thermal efficiency and low environmental load.
本発明の汚染土壌の浄化装置には、上記の汚染土壌浄化方法を用いることが好ましい。前記の汚染土壌浄化方法の原理が簡単であることから、本発明の汚染土壌の浄化装置は、比較的小型の土壌浄化装置として稼動させることが可能であり、汚染土壌を他所へ移動させずに、その場所に浄化装置を設けて汚染土壌の浄化を行うことができるという大きな効果を奏する。 The contaminated soil purification apparatus of the present invention preferably uses the above-described contaminated soil purification method. Since the principle of the contaminated soil purification method is simple, the contaminated soil purification apparatus of the present invention can be operated as a relatively small soil purification apparatus without moving the contaminated soil to another place. And, there is a great effect that the contaminated soil can be purified by providing a purification device at the place.
本発明を適用した汚染土壌の浄化装置について図４を用いて説明する。汚染土壌の分布する場所を作業がしやすい適当な大きさに区切り、予め調査した土壌が汚染されている深さまで掘り進めて、堀上げられた汚染土壌を、ベルトコンベアー（５）で、汚染土壌処理装置のホッパー（６）まで移動させる。ホッパーから円筒状ドラム（１２）の内部に攪拌用の回転するスクリュー（９）を備えたマイクロ波により昇温されるキルン内で、先ず、マグネタイト粒子を水に分散させたスラリーを汚染土壌に対してマグネタイトが１〜３重両％程度になるようにドラム中の汚染土壌に加える。回転するスクリューで十分攪拌されて、汚染土壌中にマグネタイトがほぼ均一に分布した状態でマイクロ波を照射する。スクリューの回転で移動しながら汚染土壌はマイクロ波を照射された温度が上昇する。 A contaminated soil purification apparatus to which the present invention is applied will be described with reference to FIG. The site where the contaminated soil is distributed is divided into suitable sizes that are easy to work with, and the soil that has been investigated in advance is dug up to a depth where the soil is contaminated. The excavated contaminated soil is contaminated with the belt conveyor (5). Move to the hopper (6) of the processor. In a kiln heated by a microwave equipped with a rotating screw (9) for stirring inside a cylindrical drum (12) from a hopper, first, a slurry in which magnetite particles are dispersed in water is applied to contaminated soil. The magnetite is added to the contaminated soil in the drum so that the concentration is about 1 to 3%. It is sufficiently agitated with a rotating screw and irradiated with microwaves in a state where magnetite is almost uniformly distributed in the contaminated soil. While moving by the rotation of the screw, the temperature of the contaminated soil irradiated with microwaves rises.
ここで、マイクロ波による土壌の昇温について検討すると、マイクロ波が地盤中の１立方メートル（１０6ｃｍ3）の土を分解反応が開始される最低温度である８０℃以上の温度域にさせるのに要する熱量、電力及び所要時間等の理論的数値は次のとおりである。
（１）土質：砂質土、含水比：３０％、湿潤密度：１.７０ｇ／ｃｍ3
（２）土の熱容量：１.８０Ｊ／Ｋ・ｇ
（砂、水の熱容量が夫々０.８Ｊ／Ｋ・ｇ、４.２Ｊ／Ｋ・ｇから推定）
温度勾配：０（地盤温度１５℃と仮定）、熱効率１００％（無放熱）
（１）、（２）の条件のもとに
１.８０Ｊ／Ｋ・ｇ×１.７０ｇ／ｃｍ3×１０6ｃｍ3＝３.０６×１０6Ｊ／Ｋ
３.０６×１０6Ｊ／Ｋ×（８０−１５）℃（Ｋ）＝１９.８９×１０7Ｊ
１Ｗを１秒間投入したものが１Jであるから、１９.８９×１０7Ｊを与えるには、
１００ｋｗ＝１００.０×１０3 Ｗのマイクロ波が砂に１００％吸収されるとすれば
１９.８９×１０7Ｊ÷１００.０×１０3 Ｗ／秒＝３３分となる。
Here, when examining the temperature rise of the soil by microwaves, microwaves bring the soil of 1 cubic meter (10 6 cm 3 ) in the ground to a temperature range of 80 ° C. or more, which is the lowest temperature at which the decomposition reaction starts. Theoretical numerical values such as the amount of heat, power and time required for the following are as follows.
(1) Soil: Sandy soil, moisture content: 30%, wet density: 1.70 g / cm 3
(2) Heat capacity of soil: 1.80 J / K · g
(The heat capacities of sand and water are estimated from 0.8 J / K · g and 4.2 J / K · g, respectively)
Temperature gradient: 0 (assuming a ground temperature of 15 ° C), thermal efficiency of 100% (no heat dissipation)
1.80 J / K · g × 1.70 g / cm 3 × 10 6 cm 3 = 3.06 × 10 6 J / K under the conditions of (1) and (2)
3.06 × 10 6 J / K × (80-15) ° C. (K) = 19.89 × 10 7 J
To give 19.89 × 10 7 J, 1W is 1J for 1 second.
If 100 kw = 10.0 × 10 3 W microwave is absorbed by sand 100%, 19.89 × 10 7 J ÷ 100.0 × 10 3 W / sec = 33 minutes.
攪拌と、昇温に必要な時間の関係、すなわち土壌の移動速度の関係を満たすために、スクリューは、その速度を調節し必要に応じて逆回転させることもある。 In order to satisfy the relationship between agitation and the time required for temperature increase, that is, the relationship between the moving speed of the soil, the screw may be rotated in the reverse direction as necessary by adjusting the speed.
開口１（１１A）からマイクロ波を照射されて、汚染土壌の温度は、80度C〜100度Cに昇温され、汚染土壌中の揮発性有機物質が気化して、ガス吸着槽へ導かれる。ガス吸着槽には石炭灰、セメント又は石灰、塩化カリウム、塩化マグネシウム、塩化コバルト、塩化第二鉄等の無機塩類で構成された無機系吸着剤が使用される。 The microwave is irradiated from the opening 1 (11A), and the temperature of the contaminated soil is raised to 80 ° C. to 100 ° C., and the volatile organic substance in the contaminated soil is vaporized and guided to the gas adsorption tank. . In the gas adsorption tank, an inorganic adsorbent composed of inorganic salts such as coal ash, cement or lime, potassium chloride, magnesium chloride, cobalt chloride, and ferric chloride is used.
揮発性有機化合物が十分気化した汚染土壌は、開口２（１１B）からさらにマイクロ波を照射されてその温度が温度６００度C〜７００度Cまで昇温し、この温度帯で、鉛・カドミウム・砒素などの低融点金属がマグネタイトに包摂され、さらに、開口3（１１C）からのマイクロ波を照射されて温度９００度C〜１３００度Cまで昇温した汚染土壌中では、マグネタイトにニッケル、マンガンなどの高融点の金属が包摂される。 Contaminated soil in which volatile organic compounds are sufficiently vaporized is further irradiated with microwaves from the opening 2 (11B), and the temperature rises to 600 ° C to 700 ° C. In this temperature range, lead, cadmium, In a contaminated soil in which a low melting point metal such as arsenic is included in magnetite and is heated to 900 ° C to 1300 ° C by being irradiated with microwaves from opening 3 (11C), nickel, manganese, etc. Of high melting point metals.
マグネタイトに包摂された重金属は、キルンから外へ出て、磁気分離装置（１５）へ入る。磁気分離装置では、キルンから出てきたマグネタイトに包摂された重金属を含む土壌に強力な磁界を与え、磁気に反応するマグネタイトを土壌から分離選別する。分離選別されたマグネタイトに包摂された重金属は重金属貯留槽（１６）に蓄えられ、トラックなどで、場外の重金属回収施設へ送られ、そこで、重金属が回収される。 The heavy metal included in the magnetite goes out of the kiln and enters the magnetic separation device (15). In the magnetic separation device, a strong magnetic field is applied to the soil containing the heavy metal included in the magnetite that comes out of the kiln, and the magnetite that reacts to magnetism is separated and selected from the soil. The heavy metal included in the separated and sorted magnetite is stored in the heavy metal storage tank (16) and sent to a heavy metal recovery facility off-site by a truck or the like, where the heavy metal is recovered.
本発明による処理方法においては、熱消費量がストーカー型溶融炉に比較して、1/20〜1/100以下であるので、省エネ、および環境対策としても好ましいことが分かる。また、薬剤を注入する方法に比べマグネタイトは磁気的にほぼ完全に回収されるので、残留薬剤による２次汚染などの環境負荷も少ない。 In the treatment method according to the present invention, the heat consumption is 1/20 to 1/100 or less as compared with the stalker type melting furnace, so that it can be seen that it is preferable as an energy saving and environmental measure. Moreover, since magnetite is almost completely recovered magnetically compared with the method of injecting the drug, the environmental load such as secondary contamination by the residual drug is small.
本発明は、汚染土壌を他所へ移動させることなく、オンサイトで処理することが可能な方法及び装置であるので十分な産業上の利用可能性を有する。 The present invention has sufficient industrial applicability because it is a method and apparatus that can be treated on-site without moving contaminated soil to another place.
１A〜１C キルン1〜キルン３
２A〜２C マイクロ波源
３ 磁石
４ 汚染土壌
５ ベルトコンベア
６ ホッパー
７ スラリー槽
８ スクリュー駆動用モータ
９ スクリュー
１０ マイクロ波源
１１A〜１１C 開口１〜開口３
１２ ドラム
１３ ガス吸着槽
１４ ガス貯留槽
１５ 磁気分離装置
１６ 重金属貯留槽
1A ~ 1C kiln 1 ~
2A to
12
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013088361A (en) * | 2011-10-20 | 2013-05-13 | Toshiba Corp | Soil purification system |
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| JP2013242300A (en) * | 2013-04-15 | 2013-12-05 | Prefectural Univ Of Hiroshima | Method and device for treating radioactive substance contaminant |
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