JP2018103133A - Soil treatment material and purification method of heavy metal contaminated soil - Google Patents
Soil treatment material and purification method of heavy metal contaminated soil Download PDFInfo
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本発明は、重金属汚染土壌から重金属を分離して土壌を浄化するために有用な土壌処理材に関する。 The present invention relates to a soil treatment material useful for purifying soil by separating heavy metal from soil contaminated with heavy metal.
揮発性有機化合物や重金属などの有害物質で汚染された土壌は、人体に健康被害を与える可能性があることから、特定有害物質を一定基準値以上に含有する土壌区域は指定され、何等かの土壌汚染対策を実施することが義務付けられている。重金属で汚染された土壌の場合、土壌溶出量基準として、例えば鉛やヒ素は0.01mg/L以下である。 Since soil contaminated with toxic substances such as volatile organic compounds and heavy metals may cause human health damage, a soil area containing specified hazardous substances above a certain standard value is designated. It is obliged to implement soil pollution countermeasures. In the case of soil contaminated with heavy metals, for example, lead and arsenic are 0.01 mg / L or less as the soil elution standard.
汚染土壌対策としては、廃棄物処理場での廃棄処理、不溶化処理、分別浄化、洗浄、加熱処理など各種の手法があるが、重金属汚染土壌の場合、廃棄処理や不溶化処理される場合が多い。しかし、重金属汚染土壌を運搬して廃棄物処理場で廃棄したり、不溶化処理しても、汚染土壌が残存し続けるため、土地又は土壌の有効利用が制限されることになる。 As countermeasures against contaminated soil, there are various methods such as disposal at a waste disposal site, insolubilization, separation purification, washing, and heat treatment, but in the case of heavy metal contaminated soil, disposal and insolubilization are often performed. However, even if heavy metal-contaminated soil is transported and discarded at a waste disposal site or insolubilized, contaminated soil continues to remain, which limits the effective use of land or soil.
そのため、重金属汚染土壌を効率的に浄化する方策について、種々の提案がなされており、鉄粉に重金属を吸着させる手法も知られている。 For this reason, various proposals have been made for measures for efficiently purifying heavy metal-contaminated soil, and techniques for adsorbing heavy metals on iron powder are also known.
特許文献１は、シアン化合物と重金属が鉄分と共存して磁着可能な形態で含有される土壌を磁選機に供給して土壌中のシアン化合物、重金属と鉄分の共存物を磁着、分離することにより処理対象物を減量する汚染土壌の浄化方法を開示する。しかし、積極的に鉄分を添加することは教えない。 In Patent Document 1, a soil containing cyanide and heavy metal coexisting with iron and magnetized is supplied to a magnetic separator to magnetize and separate the cyanide, heavy metal and iron coexisting material in the soil. The purification method of the contaminated soil which reduces a process target object by this is disclosed. However, it does not teach that iron is actively added.
特許文献２は、フッ素とヒ素の複合汚染土壌を浄化するために、金属鉄粉又は酸化鉄粉と、水酸化マグネシウム又は酸化マグネシウムと、pH調整剤とをバインダーで造粒してなる浄化材を開示する。特許文献３は、複合汚染土壌を浄化するために、金属鉄粉表面に希土類元素の水酸化物又は酸化物を付着した浄化材を開示する。しかし、これらの方法は、簡便さや、コストの点で実用的とは言えない。 Patent Document 2 discloses a purifying material obtained by granulating metallic iron powder or iron oxide powder, magnesium hydroxide or magnesium oxide, and a pH adjuster with a binder in order to purify the combined contaminated soil of fluorine and arsenic. Disclose. Patent Document 3 discloses a purification material in which a rare earth element hydroxide or oxide is attached to the surface of metallic iron powder in order to purify composite contaminated soil. However, these methods are not practical in terms of simplicity and cost.
特許文献４は、α鉄-酸化鉄複合化物粉末と鉄酸化物粉末との混合物を用いた重金属処理材を開示する。しかし、この手法は、重金属を不溶化処理するものであり、分離浄化するものではない。 Patent Document 4 discloses a heavy metal treatment material using a mixture of α-iron-iron oxide composite powder and iron oxide powder. However, this method insolubilizes heavy metals and does not separate and purify them.
特許文献5は、重金属等で汚染された汚染土壌に鉄粉のような金属鉄を加え、攪拌混合して汚染物を鉄に吸着又は結合させたのち、それを必要により乾燥させて、乾式で磁力分離して、汚染物を吸着又は結合した鉄と、処理土に分離する方法を開示する。この方法では、汚染物の移動速度を向上させるため、硫酸や塩酸等の酸を鉄粉と同時に添加している。
また、鉄粉自体は、重金属等の汚染物の吸着又は結合する能力が低いので、これを活性化することが望まれる。そのためにも、酸を添加することは有効であるが、トンネル工事現場や掘削現場等に近接して設けられる土壌処理現場において、濃硫酸のような危険な劇物を使用することは望ましいとは言えない。
In Patent Document 5, metal iron such as iron powder is added to contaminated soil contaminated with heavy metals, etc., and mixed by stirring to adsorb or bind the contaminants to the iron, then drying it as necessary, Disclosed is a method of separating magnetically separated iron into which soil is adsorbed or bound and treated soil. In this method, an acid such as sulfuric acid or hydrochloric acid is added simultaneously with the iron powder in order to improve the moving speed of contaminants.
Moreover, since iron powder itself has a low ability to adsorb or bind contaminants such as heavy metals, it is desired to activate it. For this purpose, it is effective to add acid, but it is desirable to use dangerous deleterious substances such as concentrated sulfuric acid at the soil treatment site provided close to the tunnel construction site or excavation site. I can not say.
本発明の目的は、硫酸のような酸を現場で使用することなく、鉄粉の表面を活性化して重金属を吸着でき、重金属汚染土壌から重金属を分離浄化するために有用な土壌処理材を提供することにある。更に、本発明は乾式による鉄粉を利用した重金属汚染の土壌浄化を安全かつ効率的に行う方法を提供する。 The object of the present invention is to provide a soil treatment material useful for separating and purifying heavy metals from heavy metal contaminated soil by activating the surface of iron powder and adsorbing heavy metals without using an acid such as sulfuric acid in the field. There is to do. Furthermore, the present invention provides a method for safely and efficiently performing soil remediation of heavy metal contamination using dry iron powder.
本発明は、重金属汚染土壌を浄化する処理材であって、表面に凹凸又は空隙を有する鉄粉に、水中で酸性を示す金属塩を担持していることを特徴とする土壌処理材である。 The present invention is a treatment material for purifying heavy metal-contaminated soil, characterized in that a metal salt showing acidity in water is supported on iron powder having irregularities or voids on the surface.
本発明の土壌処理材は、次のいずれか１つ以上を満足することが望ましい。
１）鉄粉が、アトマイズ鉄粉、還元鉄粉、又は銑ダライであること。
２）金属塩が、酸性硫酸金属塩、例えば酸性硫酸マグネシウム、酸性硫酸アルミニウムであること。
The soil treatment material of the present invention preferably satisfies any one or more of the following.
1) The iron powder is atomized iron powder, reduced iron powder, or rice bran.
2) The metal salt is an acidic metal sulfate such as acidic magnesium sulfate or acidic aluminum sulfate.
また、本発明は、重金属汚染土壌を浄化する方法であって、上記の土壌処理材を、重金属汚染土壌中に添加、撹拌、混合し、土壌中の重金属を土壌処理材に吸着させる添加、混合工程、及び磁力選別法により重金属を吸着した土壌処理材を土壌中から分離、回収する磁選工程を備えることを特徴とする重金属汚染土壌の浄化方法である。
上記添加、混合工程においては、酸が添加されないことが好ましく、上記磁選工程においては、乾式の磁力選別法により行われることが好ましい。
また、重金属汚染土壌中に、水を添加することなく、土壌処理材を混合攪拌し、乾式で磁力選別することが有効である。
Further, the present invention is a method for purifying heavy metal-contaminated soil, wherein the above-mentioned soil treatment material is added to, agitated and mixed with the heavy metal-contaminated soil, and the addition and mixing for adsorbing the heavy metal in the soil to the soil treatment material A method for purifying heavy metal-contaminated soil, comprising a magnetic separation step for separating and recovering a soil treatment material adsorbing heavy metals by a step and a magnetic separation method.
In the addition and mixing steps, it is preferable that no acid is added, and in the magnetic separation step, it is preferable to carry out by a dry magnetic separation method.
In addition, it is effective to mix and agitate the soil treatment material in the heavy metal contaminated soil without adding water and perform magnetic separation with a dry method.
本発明の土壌処理材は、鉄粉の表面又は空隙に水中で酸性を示す酸性金属塩を担持していることから、施工現場において硫酸等の薬品を添加する必要がない。重金属を吸着した土壌処理材は、磁力により土壌と分離、回収が可能であるため、簡易に汚染土壌を浄化できる。また、重金属は土壌処理材と一緒に分離されるため、処理された土壌中の重金属含有量が低下して、浄化土壌としてこれを有効に利用することができる。 Since the soil treatment material of the present invention carries an acidic metal salt that shows acidity in water on the surface or voids of iron powder, it is not necessary to add chemicals such as sulfuric acid at the construction site. Since the soil treatment material adsorbing heavy metals can be separated from the soil by magnetic force and recovered, the contaminated soil can be easily purified. Moreover, since a heavy metal is isolate | separated with a soil treatment material, heavy metal content in the processed soil falls and this can be utilized effectively as a purification | cleaning soil.
本発明の土壌処理材は、表面に微細な空隙や凹凸を有する鉄粉に水中で酸性を示す酸金属塩を担持している。 The soil treatment material of the present invention carries an acid metal salt that shows acidity in water on iron powder having fine voids and irregularities on the surface.
鉄粉としては、表面に微細な空隙又は凹凸を有するものを使用する。鉄粉の平均粒径は特に限定されないが、平均粒径（d50）は、例えば１０〜１０００μｍの範囲が好ましく、より好ましくは３０〜３００μｍ、更に好ましくは５０〜２００μｍであることができる。
このような鉄粉としては、アトマイズ鉄粉、還元鉄粉、又は銑ダライ粉が挙げられる。アトマイズ鉄粉、還元鉄粉は、製鉄工程で高圧水や副原料による還元を利用して得られる鉄粉であり、銑ダライ粉は、鋳鉄を切削、旋削した際に発生する屑である。これらの鉄粉は土壌処理用として市販されているものが適するが、その他の用途、例えば懐炉用や脱酸素材用の鉄粉であっても差し支えない。
As the iron powder, one having fine voids or irregularities on the surface is used. The average particle diameter of the iron powder is not particularly limited, but the average particle diameter (d50) is preferably in the range of, for example, 10 to 1000 μm, more preferably 30 to 300 μm, and further preferably 50 to 200 μm.
Examples of such iron powder include atomized iron powder, reduced iron powder, and rice bran powder. Atomized iron powder and reduced iron powder are iron powders obtained by using reduction with high-pressure water or auxiliary materials in the iron making process, and paddy powder is waste generated when cast iron is cut and turned. Those iron powders that are commercially available for soil treatment are suitable, but iron powders for other uses, for example, for squirrels and deoxidizing materials may be used.
鉄粉に担持される金属塩としては、水溶性で、水中で酸性を示す常温固体の金属塩が好ましく、酸性硫酸金属塩がより好ましい。水中で酸性を示す金属塩としては、強塩基を与えない金属と強酸との塩がある。かかる塩としては、硫酸鉄、硫酸アルミニウム等がある。この金属や強酸としては、それ自体が有害物質となる可能性がある重金属類やハロゲン含有酸等は望ましくない。また、アルカリ金属やアルカリ土類金属と強酸の塩は、一般に中性であるが、これを中和するに足る量以上の酸を使用すれば、酸性塩となって、水中で酸性を示すものとなる。アルカリ金属やアルカリ土類金属以外の金属であっても、酸性塩とすることにより、効果が増大する。好ましい酸性塩としては、酸性硫酸マグネシウム、酸性硫酸アルミニウムがある。 The metal salt supported on the iron powder is preferably a solid metal salt that is water-soluble and shows acidity in water, and more preferably an acidic metal sulfate. As a metal salt which shows acidity in water, there is a salt of a metal and a strong acid that does not give a strong base. Such salts include iron sulfate, aluminum sulfate and the like. As the metal and strong acid, heavy metals and halogen-containing acids that may be harmful substances are not desirable. Alkali metal or alkaline earth metal and strong acid salts are generally neutral, but if they use more acid than is sufficient to neutralize them, they become acidic and show acidity in water. It becomes. Even if it is a metal other than an alkali metal or an alkaline earth metal, the effect is increased by using an acid salt. Preferred acidic salts include acidic magnesium sulfate and acidic aluminum sulfate.
例えば、酸性硫酸マグネシウム、酸性硫酸アルミニウムは、MgOやAlやAl(OH)3等の金属又は金属化合物に対して、これを中和するに必要な量より過剰の硫酸を反応させることにより得ることができる。例えば、無水の硫酸マグネシウムはMgOとして約33％含むが、Mg(HSO4)2のような形態をとると考えた場合はMgOとして約18％含むことになる。したがって、MgOの含有率から酸性硫酸マグネシウムにおける理論量より過剰の酸の量が計算可能である。 For example, acidic magnesium sulfate and acidic aluminum sulfate are obtained by reacting a metal or metal compound such as MgO, Al or Al (OH) 3 with an excess of sulfuric acid in an amount necessary to neutralize it. Can do. For example, anhydrous magnesium sulfate contains about 33% as MgO, but when it is considered to take a form such as Mg (HSO 4 ) 2 , it contains about 18% as MgO. Therefore, the amount of acid in excess of the theoretical amount in acidic magnesium sulfate can be calculated from the MgO content.
水中で酸性を示す金属塩を与える金属としては、アルカリ金属、アルカリ土類金属、アルミニウム、鉄等の無害で、金属塩を形成するものを挙げることができる。酸としては、硫酸、リン酸等の無害で、酸性塩を形成するものを挙げることができるが硫酸が適する。
特に、酸性硫酸マグネシウム、及び酸性硫酸アルミニウムは市販品があるので、入手も容易である。また、硫酸鉄や硫酸アルミニウムも水中で酸性を示し、入手が容易であるので金属塩として適する。
Examples of the metal that gives a metal salt that is acidic in water include alkali metals, alkaline earth metals, aluminum, iron, and the like that form harmless metal salts. Examples of the acid include those that are harmless, such as sulfuric acid and phosphoric acid, and form acid salts, but sulfuric acid is suitable.
In particular, since acidic magnesium sulfate and acidic aluminum sulfate are commercially available, they are easily available. Iron sulfate and aluminum sulfate are also suitable as metal salts because they are acidic in water and are readily available.
金属塩は、通常粉末状であり、無水物、水和物のいずれでもよい。酸性金属塩は、水中に溶解した際、酸性を示し、これによって鉄粉と反応し、鉄粉表面を活性化し、更に土壌中の重金属の移動を促進して効果的に吸着することができる。
土壌処理材10ｇを100mlの水中に投入し攪拌したときのpHは、1〜５程度がよい。
The metal salt is usually in a powder form and may be either an anhydride or a hydrate. The acidic metal salt exhibits acidity when dissolved in water, thereby reacting with the iron powder, activating the iron powder surface, and further promoting the movement of heavy metal in the soil and effectively adsorbing it.
The pH when the soil treatment material 10 g is put into 100 ml of water and stirred is preferably about 1 to 5.
酸性金属塩の担持量は、処理すべき土壌の性状によっても相違するが、土壌処理材の０．５〜７５重量％であることがよく、好ましくは１〜３０重量％、より好ましくは２〜２５重量％である。 The amount of the acidic metal salt supported varies depending on the properties of the soil to be treated, but is preferably 0.5 to 75% by weight of the soil treatment material, preferably 1 to 30% by weight, more preferably 2 to 2%. 25% by weight.
磁選法による鉄粉を使用した重金属汚染土壌の処理方法としては、水を添加して土壌をスラリー化する湿式法と乾式法があるが、いずれにも適用可能である。乾式磁選法では、汚染土壌中に土壌処理材を混入することによって、土壌中の水分を利用して酸性イオンが土壌中に溶け出し、鉄や重金属と反応し、重金属を効率よく吸着することができる。 As a method for treating heavy metal-contaminated soil using iron powder by magnetic separation, there are a wet method and a dry method in which water is added to slurry the soil, and any method can be applied. In dry magnetic separation, by mixing soil treatment material into contaminated soil, acid ions dissolve into the soil using moisture in the soil, react with iron and heavy metals, and efficiently adsorb heavy metals. it can.
本発明の土壌処理材は、重金属、例えば鉛、ヒ素、カドミウム、水銀などを吸着分離するのに有効であるが、特に鉛、ヒ素を吸着分離するのに好適である。また、本発明の土壌処理材は、シアン、セレン、フッ素、ホウ素等の重金属以外の有害物質を除去する機能が期待される。鉄粉が水分の存在下で、酸性金属塩中の酸成分や土壌中の酸素や水分と反応し、これらの重金属を吸着して捕捉することができる。ここで、重金属の吸着とは、物理的な吸着だけでなく、鉄粉から生じる酸化鉄、水酸化鉄、シュベルトマナイト等の化合物と重金属が反応して不溶性の化合物として結合することを含む。このような反応は主に鉄粉の表面で生じるので、磁力により鉄粉に吸着した状態で分離される。 The soil treatment material of the present invention is effective for adsorbing and separating heavy metals such as lead, arsenic, cadmium, and mercury, but is particularly suitable for adsorbing and separating lead and arsenic. The soil treatment material of the present invention is expected to have a function of removing harmful substances other than heavy metals such as cyan, selenium, fluorine and boron. In the presence of moisture, iron powder reacts with acid components in acidic metal salts, oxygen and moisture in soil, and can adsorb and capture these heavy metals. Here, the adsorption of heavy metal includes not only physical adsorption but also a reaction between a compound such as iron oxide, iron hydroxide, and Schwermanite generated from iron powder and binding as an insoluble compound. Since such a reaction mainly occurs on the surface of the iron powder, it is separated while adsorbed to the iron powder by magnetic force.
本発明の土壌処理材の使用量は、処理すべき汚染土壌の性状等によって異なるが、土壌１ｍ３に対して、例えば１〜２００ｋｇ、好ましくは２〜１００ｋｇの範囲が適する。そして、処理後の土壌中に含まれる重金属が、土壌環境基準に適合する量に低減できるように使用する。なお、使用にあたり、土壌処理材は、汚染土壌中に混合攪拌される。これによって、汚染土壌中に土壌処理材が均一に分散され、土壌中の水分で酸性を示す酸性金属塩によって鉄粉が活性化され、土壌中に含まれる重金属を十分に吸着することができる。なお、本発明の土壌処理材を使用しても、硫酸イオンはシュベルトマナイト等の鉄化合物となって不溶化され、また土壌は弱酸性〜弱アルカリであり、その緩衝作用があることから、土壌が強酸性になることはない。 The amount of soil treatment material of the present invention varies depending properties such contaminated soil to be treated, with respect to the soil 1 m 3, for example 1～200Kg, preferably suitably in the range of 2～100Kg. And it uses so that the heavy metal contained in the soil after a process can be reduced to the quantity which conforms to a soil environmental standard. In use, the soil treatment material is mixed and stirred into the contaminated soil. As a result, the soil treatment material is uniformly dispersed in the contaminated soil, the iron powder is activated by the acidic metal salt that shows acidity with the moisture in the soil, and the heavy metal contained in the soil can be sufficiently adsorbed. Even if the soil treatment material of the present invention is used, sulfate ions are insolubilized as iron compounds such as schbertmanite, and the soil is weakly acidic to weakly alkaline and has a buffering action. Does not become strongly acidic.
土壌処理材と汚染土壌を均一に混合するためには、汚染土壌が細粒にばらけやすいことが望ましい。そのため、水分量を調整することがよい。乾式法での適切な水分量は、５〜６０重量％、好ましくは１０〜５０重量％の範囲であるが、水分量が少ないと酸性金属塩の溶出や反応が生じにくくなる。しかし、酸又は酸水溶液は添加しないことがよい。 In order to uniformly mix the soil treatment material and the contaminated soil, it is desirable that the contaminated soil be easily dispersed into fine particles. Therefore, it is better to adjust the moisture content. The appropriate amount of water in the dry method is in the range of 5 to 60% by weight, preferably 10 to 50% by weight. However, if the amount of water is small, elution of the acidic metal salt and reaction hardly occur. However, it is preferable not to add an acid or an aqueous acid solution.
汚染土壌の処理は、土壌処理材を汚染土壌に添加し、これをドラムミキサー等で均一に攪拌、混合し、所定時間、攪拌、放置して、反応を行うことがよい。 The treatment of contaminated soil is preferably performed by adding a soil treatment material to the contaminated soil, stirring and mixing the mixture uniformly with a drum mixer or the like, and stirring and leaving for a predetermined time.
添加、攪拌、混合工程を終了した後は、磁選工程において、磁力により鉄粉を含む土壌処理材を、土壌から分離する。これは、公知の磁石を備えた分離装置で行うことができる。これにより、土壌中の重金属を吸着した土壌処理材と、重金属が除去された浄化土壌とに分離される。
浄化土壌は、通常の土壌としての利用が可能であり、有用な資源となる。一方、重金属を吸着した土壌処理材は、重金属の濃度は高いとしても、少量であるから、無害化処理や固化処理、廃棄処理等が容易である。
After completing the addition, stirring, and mixing steps, the soil treatment material containing iron powder is separated from the soil by magnetic force in the magnetic separation step. This can be done with a separation device equipped with a known magnet. Thereby, it isolate | separates into the soil treatment material which adsorb | sucked the heavy metal in soil, and the purification | cleaning soil from which the heavy metal was removed.
The purified soil can be used as normal soil and is a useful resource. On the other hand, even if the concentration of heavy metals is high, the soil treatment material that adsorbs heavy metals is easy to be detoxified, solidified, discarded, and the like.
本発明の土壌処理材は、トンネル工事や掘削工事で発生する重金属汚染土壌の処理に有用である。特に、乾式で磁力選別を行う処理に適する。また、重金属汚染土壌は、鉱山・精錬施設、都市部の工場跡地などの他、自然由来による場合もあり、これらの重金属汚染土壌を処理することによって、重金属を環境基準値以下に低減することに有効である。 The soil treatment material of the present invention is useful for treating heavy metal contaminated soil generated in tunnel construction and excavation construction. In particular, it is suitable for a dry type magnetic separation process. In addition, heavy metal contaminated soil may be derived from natural sources in addition to mines and smelting facilities, factory sites in urban areas, etc., and by treating these heavy metal contaminated soil, the heavy metals will be reduced below the environmental standard value. It is valid.
以下、本発明を、実施例によって具体的に説明するが、これらによって限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, it is not limited by these.
実施例１〜６
市販の還元鉄粉（JFEスチール社製、金属鉄９７．５5％、見掛密度２．７３g/cm3、流動度２３．０、粒度分布（150〜106メッシュ；５９．０％））と、酸性硫酸マグネシウム（MgO含有量＝２７〜２８wt%、pH３、営口豊達硼製品有限公司社製）を、表１に示す割合でスーパーミキサーを使用して混合攪拌し、土壌処理材１〜７を作製した。
Examples 1-6
Commercially available reduced iron powder (manufactured by JFE Steel, 97.55% metallic iron, apparent density 2.73 g / cm 3 , fluidity 23.0, particle size distribution (150 to 106 mesh; 59.0%)), Acid magnesium sulfate (MgO content = 27 to 28 wt%, pH 3, Yingkou Toyoda Boron Products Co., Ltd.) was mixed and stirred using a super mixer at the ratio shown in Table 1, and soil treatment materials 1 to 7 were mixed. Produced.
実施例８〜１４
ヒ素含有岩石の浸出水（ヒ素濃度１．６０mg/L）１００mL中に、実施例１〜７で得た土壌処理材１〜７をそれぞれ０．５g添加し、２５℃で６時間攪拌し、接触させた。２４時間後、溶液をミリポアフィルターでろ過し、ろ液中のヒ素濃度を公定法により測定した。また、溶液の状態を目視により観察するとともに、ｐＨを測定した。その結果を表２〜３に示す。
なお、溶液の状態が黄褐色懸濁（YBS）である場合、鉄粉表面が活性化し、ヒ素を捕捉し、水酸化鉄として懸濁していることを示す。一方、溶液の状態が無色透明（CLT）である場合、鉄粉が不動態化し、ヒ素が捕捉されていないことを示す。表中、溶液の状態において、YBTは黄褐色透明を、YTは黄色透明を意味する。
Examples 8-14
0.5 g of each of the soil treatment materials 1 to 7 obtained in Examples 1 to 7 was added to 100 mL of leachate of arsenic-containing rock (arsenic concentration 1.60 mg / L), stirred at 25 ° C. for 6 hours, and contacted. I let you. After 24 hours, the solution was filtered through a Millipore filter, and the arsenic concentration in the filtrate was measured by an official method. Moreover, while observing the state of a solution visually, pH was measured. The results are shown in Tables 2-3.
In addition, when the state of a solution is yellowish brown suspension (YBS), the iron powder surface is activated, it shows that arsenic is captured and suspended as iron hydroxide. On the other hand, when the state of the solution is colorless and transparent (CLT), the iron powder is passivated, indicating that arsenic is not captured. In the table, YBT means yellowish brown and YT means yellowish transparent in the solution state.
比較例１〜２
実施例１で使用したと同じ還元鉄粉及び酸性硫酸マグネシウムをそれぞれ単独で使用して、土壌処理材H1（還元鉄粉100％）、土壌処理材H2（酸性硫酸マグネシウム100％）とした。
この土壌処理材H1及びH2を、実施例８〜１４と同様にヒ素含有岩石の浸出水に添加し、評価した。その結果を表３に示す。
本発明の土壌処理材は、ヒ素の除去能力が高いことが示された。
Comparative Examples 1-2
The same reduced iron powder and acidic magnesium sulfate as used in Example 1 were used alone to obtain soil treatment material H1 (reduced iron powder 100%) and soil treatment material H2 (acidic magnesium sulfate 100%).
The soil treatment materials H1 and H2 were added to the leachate of the arsenic-containing rock in the same manner as in Examples 8 to 14, and evaluated. The results are shown in Table 3.
It was shown that the soil treatment material of the present invention has a high ability to remove arsenic.
実施例１５〜１６、比較例３〜４
市販の還元鉄粉の代わりに市販のアトマイズ鉄粉（JFEスチール社製）又は銑ダライ（同社製）を用いた他は、実施例１と同様にして土壌処理材８、及び９を作製した。また、上記アトマイズ鉄粉又は銑ダライを単独で用いて土壌処理材H３〜H４とした。土壌処理材を表４に示す。
実施例８〜１４で使用したと同じヒ素含有岩石の浸出水（ヒ素濃度１．６０mg/L）１００mL中に、土壌処理材８〜９、H３〜H４をそれぞれ０．５g添加し、２５℃で６時間攪拌し、接触させた。２４時間後、溶液をミリポアフィルターでろ過し、ろ液中のヒ素濃度を公定法により測定した。また、溶液の状態を目視により観察するとともに、ｐＨを測定した。その結果を表５に示す。
Examples 15-16, Comparative Examples 3-4
Soil treatment materials 8 and 9 were prepared in the same manner as in Example 1 except that a commercially available atomized iron powder (manufactured by JFE Steel) or Kada Dalai (manufactured by the same company) was used instead of the commercially available reduced iron powder. Moreover, it was set as the soil treatment materials H3-H4 using the said atomized iron powder or rice bran alone. Table 4 shows the soil treatment materials.
In 100 mL of leached water (arsenic concentration 1.60 mg / L) of the same arsenic-containing rock used in Examples 8 to 14, 0.5 g of soil treatment materials 8 to 9 and H3 to H4 were added, respectively, at 25 ° C. Stir for 6 hours and contact. After 24 hours, the solution was filtered through a Millipore filter, and the arsenic concentration in the filtrate was measured by an official method. Moreover, while observing the state of a solution visually, pH was measured. The results are shown in Table 5.
実施例１７〜１８
実施例１〜６で使用したと同じ鉄粉と、硫酸第一鉄（粉末状工業用薬品；石原産業社製）、硫酸アルミニウム（粉末状工業用薬品；大明化学社製）を使用し、表６に示す混合比率でスーパーミキサーを使用して混合攪拌し、土壌処理材１０、１１を作製した。
Examples 17-18
Using the same iron powder as used in Examples 1 to 6, ferrous sulfate (powdered industrial chemical; manufactured by Ishihara Sangyo Co., Ltd.), aluminum sulfate (powdered industrial chemical; manufactured by Daimei Chemical Co., Ltd.), The soil treatment materials 10 and 11 were produced by mixing and stirring using a super mixer at a mixing ratio shown in FIG.
実施例１９〜２１
重金属含有土壌として、化学工場跡地から発生したヒ素汚染土壌（含水率２６％）を使用した（汚染土壌１）。この汚染土壌に土壌処理材１０、１１及び３を、表７に示す量で添加し、卓上ミキサーで10分間攪拌、混合した。得られた処理土壌について溶出量試験（環境省告示第１８号）を実施した。結果を表７に示す。参考例は、土壌処理材を添加しない例であり、基準となる。
Examples 19-21
As the heavy metal-containing soil, arsenic-contaminated soil (water content 26%) generated from the site of the chemical factory was used (contaminated soil 1). Soil treatment materials 10, 11 and 3 were added to the contaminated soil in the amounts shown in Table 7, and the mixture was stirred and mixed for 10 minutes with a desktop mixer. An elution amount test (Ministry of the Environment Notification No. 18) was conducted on the obtained treated soil. The results are shown in Table 7. The reference example is an example in which no soil treatment material is added, and serves as a reference.
比較例５〜７
実施例１９で使用したと同じ汚染土壌１に、土壌処理材H１を表１０に示す量で添加し、卓上ミキサーで10分間混合した。得られた処理土壌について溶出量試験を実施した。結果を表８に示す。
Comparative Examples 5-7
Soil treatment material H1 was added to the same contaminated soil 1 used in Example 19 in the amount shown in Table 10, and mixed for 10 minutes with a desktop mixer. An elution amount test was performed on the obtained treated soil. The results are shown in Table 8.
比較例８〜１０
汚染土壌１に、土壌処理材H１と、濃硫酸（比重１．８４；和光純薬工業(株)製）を表１０に示す量で添加し、卓上ミキサーで10分間混合した。得られた処理土壌について溶出量試験を実施した。結果を表８に示す。
Comparative Examples 8-10
Soil treatment material H1 and concentrated sulfuric acid (specific gravity 1.84; manufactured by Wako Pure Chemical Industries, Ltd.) were added to the contaminated soil 1 in the amounts shown in Table 10, and mixed for 10 minutes with a desktop mixer. An elution amount test was performed on the obtained treated soil. The results are shown in Table 8.
実施例２２〜２４
実施例１９で使用したと同じ汚染土壌１に、実施例１９〜２１で使用したと同じ土壌処理材１０、１１及び３を、表９に示す量で添加し、卓上ミキサーで10分間混合した。得られた処理土壌を、樹脂性トレイに開けて薄く敷均し、ポリ袋中に挿入した４０ｍｍ×２５ｍｍ×厚さ１５ｍｍで、表面磁束密度３９２．９ｍＴのネオジム磁石を満遍なく処理土壌と接触させて、磁着物粒子を磁性分離除去し、処理土壌について溶出量試験（環境省告示第１８号）を実施した。結果を表９に示す。磁性分離除去後重量（wt%）は、磁性分離前を100 wt%として計算された値である。なお、磁着物粒子量（wt%）は、100−磁性分離除去後重量（wt%）で計算される。
本発明による土壌処理材の添加と磁着物粒子の磁性分離除去により、汚染物質溶出量が低下することが示された。
Examples 22-24
To the same contaminated soil 1 as used in Example 19, the same soil treatment materials 10, 11 and 3 as used in Examples 19 to 21 were added in the amounts shown in Table 9, and mixed for 10 minutes with a tabletop mixer. The obtained treated soil was opened thinly on a resin tray, spread thinly, and a neodymium magnet having a surface magnetic flux density of 392.9 mT, which was inserted into a plastic bag with a size of 40 mm × 25 mm × 15 mm, was evenly contacted with the treated soil. The magnetic deposit particles were separated and removed, and the treated soil was subjected to an elution amount test (Ministry of the Environment Notification No. 18). The results are shown in Table 9. The weight after magnetic separation removal (wt%) is a value calculated with 100 wt% before magnetic separation. The amount of magnetized particles (wt%) is calculated as 100−weight after magnetic separation (wt%).
It was shown that the amount of pollutant elution is reduced by the addition of the soil treatment material and the magnetic separation and removal of the magnetic deposit particles according to the present invention.
比較例１１〜１３
実施例１９で使用したと同じ汚染土壌１に土壌処理材H1を、表１０に示す量（重量％）で添加し、卓上ミキサーで10分間混合した。得られた処理土壌を、樹脂性トレイに開けて薄く敷均し、ポリ袋中に挿入した４０ｍｍ×２５ｍｍ×厚さ１５ｍｍで、表面磁束密度３９２．９ｍＴのネオジム磁石を満遍なく処理土壌と接触させて、磁着物粒子を磁性分離除去し、処理土壌について溶出量試験を実施した。結果を表１０に示す。
Comparative Examples 11-13
Soil treatment material H1 was added to the same contaminated soil 1 used in Example 19 in the amount (% by weight) shown in Table 10, and mixed for 10 minutes with a desktop mixer. The obtained treated soil was opened thinly on a resin tray, spread thinly, and a neodymium magnet having a surface magnetic flux density of 392.9 mT, which was inserted into a plastic bag with a size of 40 mm × 25 mm × 15 mm, was evenly contacted with the treated soil. The magnetic deposit particles were separated and removed, and the treated soil was subjected to an elution amount test. The results are shown in Table 10.
比較例１４〜１６
汚染土壌１に土壌処理材H1と、濃硫酸を表１０に示す量で添加し、卓上ミキサーで10分間混合した。得られた処理土壌を、樹脂性トレイに開けて薄く敷均し、ポリ袋中に挿入した４０ｍｍ×２５ｍｍ×厚さ１５ｍｍで、表面磁束密度３９２．９ｍＴのネオジム磁石を満遍なく処理土壌と接触させて、磁着物粒子を磁性分離除去し、処理土壌について溶出量試験を実施した。結果を表１０に示す。
Comparative Examples 14-16
Soil treatment material H1 and concentrated sulfuric acid were added to the contaminated soil 1 in the amounts shown in Table 10, and mixed for 10 minutes with a desktop mixer. The obtained treated soil was opened thinly on a resin tray, spread thinly, and a neodymium magnet having a surface magnetic flux density of 392.9 mT, which was inserted into a plastic bag with a size of 40 mm × 25 mm × 15 mm, was evenly contacted with the treated soil. The magnetic deposit particles were separated and removed, and the treated soil was subjected to an elution amount test. The results are shown in Table 10.
実施例２５〜２８
重金属含有土壌として、化学工場跡地から発生した汚染土壌（含水率２５％）を使用した（汚染土壌２）。この汚染土壌に実施例３の土壌処理材３を、表１１に示す量で添加し、混合機で10分間混合した。得られた処理土壌を、樹脂性トレイに開けて薄く敷均し、ポリ袋中に挿入した３０ｍｍ×４０ｍｍ×厚さ１０ｍｍのネオジウム磁石を満遍なく処理土壌と接触させて、磁着物粒子を磁性分離除去し、処理土壌について溶出量試験を実施した。結果を表１１に示す。
Examples 25-28
As heavy metal-containing soil, contaminated soil (water content 25%) generated from the former site of the chemical factory was used (contaminated soil 2). To this contaminated soil, the soil treatment material 3 of Example 3 was added in the amount shown in Table 11, and mixed for 10 minutes with a mixer. The treated soil obtained is opened on a resin tray, spread thinly, and a 30 mm x 40 mm x 10 mm thick neodymium magnet inserted in a plastic bag is brought into contact with the treated soil evenly to separate and remove magnetic deposit particles. Then, an elution amount test was performed on the treated soil. The results are shown in Table 11.
実施例２９〜３１
重金属含有土壌として、化学工場跡地から発生した汚染土壌（含水率２７％）を使用した（汚染土壌３）。この汚染土壌に実施例１７の土壌処理材１０を、表１２に示す量で添加し、混合機で10分間混合した。得られた処理土壌を、樹脂性トレイに開けて薄く敷均し、ポリ袋中に挿入した３０ｍｍ×４０ｍｍ×厚さ１０ｍｍのネオジウム磁石を満遍なく処理土壌と接触させて、磁着物粒子を磁性分離除去し、処理土壌について溶出量試験を実施した。結果を表１２に示す。
Examples 29-31
As the heavy metal-containing soil, contaminated soil (water content 27%) generated from the site of the chemical factory was used (contaminated soil 3). To this contaminated soil, the soil treatment material 10 of Example 17 was added in the amount shown in Table 12, and mixed for 10 minutes with a mixer. The treated soil obtained is opened on a resin tray, spread thinly, and a 30 mm x 40 mm x 10 mm thick neodymium magnet inserted in a plastic bag is brought into contact with the treated soil evenly to separate and remove magnetic deposit particles. Then, an elution amount test was performed on the treated soil. The results are shown in Table 12.
実施例３２〜３４
重金属含有土壌として、化学工場跡地から発生した流動性を有する汚染土壌（含水率３０％）を使用した（汚染土壌４）。この汚染土壌に実施例１８の土壌処理材１１を、表１３に示す量で添加し、混合機で10分間混合した。得られた処理土壌は、流動性が解消し磁力選別が可能な状態となったため、樹脂性トレイに開けて薄く敷均し、ポリ袋中に挿入した３０ｍｍ×４０ｍｍ×厚さ１０ｍｍのネオジウム磁石を満遍なく処理土壌と接触させて、磁着物粒子を磁性分離除去し、処理土壌について溶出量試験を実施した。結果を表１３に示す。本発明による土壌処理材の添加と磁着物粒子の磁性分離除去により、汚染物質溶出量が低下することが示された。また、含水率が高く流動性を有する汚染土壌に対して、通常では添加される中性固化材の使用なしでも、磁性分離が比較的しやすく、中性固化材の添加は不要であった。
Examples 32-34
As the heavy metal-containing soil, the contaminated soil having a fluidity (water content 30%) generated from the site of the chemical factory was used (contaminated soil 4). To this contaminated soil, the soil treatment material 11 of Example 18 was added in the amount shown in Table 13, and mixed for 10 minutes with a mixer. Since the treated soil thus obtained is in a state where the fluidity is eliminated and magnetic selection is possible, the neodymium magnet having a size of 30 mm × 40 mm × thickness 10 mm inserted in a plastic bag is opened by opening on a resin tray and thinly placed. The magnetic deposit particles were separated and removed by contact with the treated soil evenly, and an elution amount test was performed on the treated soil. The results are shown in Table 13. It was shown that the amount of pollutant elution is reduced by the addition of the soil treatment material and the magnetic separation and removal of the magnetic deposit particles according to the present invention. Moreover, magnetic separation is relatively easy without using a neutral solidifying material that is normally added to contaminated soil having a high water content and fluidity, and the addition of a neutral solidifying material is unnecessary.
Claims (7)
The method for purifying heavy metal-contaminated soil according to claim 5 or 6, wherein the magnetic separation step is performed by a dry magnetic separation method.
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