JP2005186057A - Cleaning method for contaminated soil - Google Patents

Cleaning method for contaminated soil Download PDF

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JP2005186057A
JP2005186057A JP2004196242A JP2004196242A JP2005186057A JP 2005186057 A JP2005186057 A JP 2005186057A JP 2004196242 A JP2004196242 A JP 2004196242A JP 2004196242 A JP2004196242 A JP 2004196242A JP 2005186057 A JP2005186057 A JP 2005186057A
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soil
water
slurry
carbide
contaminated soil
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Masayuki Kusuda
雅之 楠田
Noriyuki Honma
憲之 本間
Kosuke Kimoto
浩介 木本
Kazuo Abe
一雄 阿部
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Mitsui Engineering and Shipbuilding Co Ltd
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Mitsui Engineering and Shipbuilding Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning soil by efficiently separating an oily substance from the soil contaminated with the oily substance. <P>SOLUTION: The cleaning method for the contaminated soil for cleaning the soil by separating the oily substance from the contaminated soil mixed with the oily substance is constituted such that it includes a water washing step for adding water to the contaminated soil, stirring it and separating the floated up oil content from the soil with water; a slurrying step for preparing a slurry by adding water and fine powdery carbonized matter to the soil after washed with water; and a carbonized matter recovery step for recovering the fine powdery carbonized matter in the slurry by floatation. If necessary, a stirring step with high shearing force can be provided before the carbonized matter recovery step. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、汚染土壌の浄化方法に関し、詳細には油状物質で汚染された土壌を浄化する方法に関する。   The present invention relates to a method for purifying contaminated soil, and more particularly to a method for purifying soil contaminated with oily substances.

原油採掘現場や石油精製現場などにおいては、石油系油分などによる土壌汚染が問題になっており、その対策が求められている。このため、タールやオイルなどの有機物で汚染された土壌から炭化水素を回収する方法として、水スラリー化した汚染土壌に微粉砕石炭を加えるか、あるいは微粉砕石炭と水のスラリー中に汚染土壌を加えた後、混転、篩い分け、浮遊選別を行う方法が提案されている（例えば、特許文献１参照）。   In crude oil mining sites and oil refining sites, soil contamination due to petroleum-based oils is a problem, and countermeasures are required. For this reason, as a method of recovering hydrocarbons from soil contaminated with organic matter such as tar and oil, finely ground coal is added to the water-slurried contaminated soil, or contaminated soil is added to the finely ground coal and water slurry. After the addition, a method of tumbling, sieving, and floating selection has been proposed (see, for example, Patent Document 1).

特許第２８４６４６２号公報（特許請求の範囲など）Japanese Patent No. 2846462 (claims, etc.)

前記特許文献１の方法では、汚染土壌に含まれるタール分やオイル分の全量を微粉砕石炭に付着させねばならないため、大量の微粉砕石炭を必要とし、処理コストが高くなるという問題がある。また、微粉砕石炭に吸着したタールやオイルと、無機物である土壌とを分離するためには、混転装置および高せん断攪拌機を用いて、それぞれ数分〜十数分程度の比較的長い時間をかけて混転や攪拌を実施する必要がある。さらに、混転や攪拌に長い時間を要すると、大量の汚染土壌を処理する場合に混転装置や攪拌装置を大型化しなければならず、この点も実用性を高める上での隘路となっている。   The method of Patent Document 1 has a problem in that a large amount of finely pulverized coal is required because the entire amount of tar and oil contained in the contaminated soil must be adhered to the finely pulverized coal, which increases the processing cost. In addition, in order to separate tar and oil adsorbed on finely pulverized coal and inorganic soil, using a tumble device and a high shear stirrer, a relatively long time of about several minutes to several tens of minutes is used. It is necessary to carry out tumbling and stirring. Furthermore, if a long time is required for the tumbling and stirring, the tumbling device and the stirring device must be enlarged when treating a large amount of contaminated soil, and this is also a bottleneck in enhancing practicality. Yes.

また、油に汚染された土壌を浄化する場合、大きな比表面積を持つ微細な土壌粒子と油状物質との分離を、いかに効率良く行えるか、が最大の課題となる。   In addition, when purifying soil contaminated with oil, the most important issue is how to efficiently separate fine soil particles having a large specific surface area from oily substances.

従って、本発明の目的は、油状物質で汚染された土壌から、該油状物質を効率よく分離し、土壌を浄化する方法を提供することにある。   Accordingly, an object of the present invention is to provide a method for efficiently separating an oily substance from soil contaminated with the oily substance and purifying the soil.

上記課題を解決するため、本発明の第１の態様は、油状物質で汚染された土壌から該油状物質を分離して土壌を浄化する汚染土壌の浄化方法であって、汚染土壌に水を加えて攪拌し、浮上する油分を水とともに土壌から分離する水洗浄工程と、水洗浄後の土壌に水と微粉状炭化物を加えてスラリーを調製するスラリー化工程と、前記スラリー中の微粉状炭化物を浮選によって回収する炭化物回収工程と、を含むことを特徴とする、汚染土壌の浄化方法である。   In order to solve the above problems, a first aspect of the present invention is a method for purifying contaminated soil in which the oily substance is separated from the soil contaminated with the oily substance to purify the soil, and water is added to the contaminated soil. A water washing step of separating the floating oil from the soil together with water, a slurrying step of preparing a slurry by adding water and fine powdered carbide to the water-washed soil, and a fine powdered carbide in the slurry It is a purification method of contaminated soil characterized by including the carbide recovery process collected by flotation.

第１の態様では、スラリー化に先だって水洗浄工程を設け、汚染土壌中の油状物質の中で浮上分離可能な油分を水とともに分離する。これにより、油状物質の量を大幅に減らすことが可能になる。従って、その後のスラリー化工程で添加する微粉状炭化物の量も少なくてすみ、処理コストを抑制できる。また、残りの油状物質は浮選により微粉状炭化物に同伴して土壌と分離することができるので、高い浄化性能が得られる。   In the first aspect, a water washing step is provided prior to slurrying, and oil components that can be floated and separated in the oily substance in the contaminated soil are separated together with water. This makes it possible to greatly reduce the amount of oily substance. Therefore, the amount of fine powder carbide added in the subsequent slurrying process can be reduced, and the processing cost can be suppressed. Further, since the remaining oily substance can be separated from the soil by flotation with the fine powdered carbide, high purification performance can be obtained.

また、本発明の第２の態様は、第１の態様において、前記炭化物回収工程の前に、前記スラリーにせん断力を加えて攪拌する攪拌工程を設けたことを特徴とする、汚染土壌の浄化方法である。   Further, the second aspect of the present invention is the purification of contaminated soil according to the first aspect, characterized in that, before the carbide recovery step, a stirring step of applying a shearing force to the slurry and stirring is provided. Is the method.

第２の態様では、前記スラリーを高せん断力下で攪拌する。これによって、微粉状炭化物の粒子と油状物質にせん断活性面が形成され、このせん断活性面の発生により、過渡的現象として表面エネルギーが相対的に上昇し、微粉状炭化物の表面に油状物質の薄膜が形成される。このように表面改質された微粉状炭化物には、油状物質が薄膜状に添着した状態で同伴される上、スラリー中の遊離油状物質も融合一体化しやすくなるので、浮選における分離効率が大幅に向上する。つまり、第２の態様では、第１の態様と同様の作用効果に加え、汚染土壌に対してさらに高度な浄化処理が可能になる。   In the second aspect, the slurry is stirred under a high shear force. As a result, a shear active surface is formed on the finely divided carbide particles and the oily substance, and the generation of this shear active surface relatively increases the surface energy as a transient phenomenon, and the oily substance thin film is formed on the surface of the finely divided carbide. Is formed. The surface-modified fine powdered carbide is accompanied by an oily substance attached in a thin film, and the free oily substance in the slurry is easily fused and integrated. To improve. That is, in the second mode, in addition to the same effects as those in the first mode, it is possible to perform a further advanced purification process on the contaminated soil.

また、本発明の第３の態様は、第１の態様または第２の態様において、前記スラリー化工程は、水洗浄後の土壌に微粉状炭化物を加えて混練した後、水を加えてスラリー化するものであることを特徴とする、汚染土壌の浄化方法である。   In addition, according to a third aspect of the present invention, in the first aspect or the second aspect, the slurrying step includes adding fine powdered carbides to the soil after washing with water and kneading, and then adding water to make a slurry. This is a method for remediating contaminated soil.

第３の態様では、水洗浄後の土壌をスラリー化する際に、まず微粉状炭化物を添加して混練を実施し、油状物質と微粉状炭化物を十分に接触させる。この混練を行うことにより、その後のスラリー中で土壌粒子に付着した油状物質の乖離と親油性の微粉状炭化物への移行が速やかに進行するため、土壌粒子と油状物質との分離を短時間で効率良く行うことができる。   In the third aspect, when the soil after washing with water is slurried, the fine powdered carbide is first added and kneaded to sufficiently contact the oily substance and the fine powdered carbide. By performing this kneading, the separation of the oily substance adhering to the soil particles in the subsequent slurry and the transition to the lipophilic fine powdered carbide proceed quickly, so that the separation of the soil particles and the oily substance can be performed in a short time. It can be done efficiently.

また、本発明の第４の態様は、第１の態様乃至第３の態様のいずれかにおいて、前記水洗浄工程は５０℃以上の温水を使用することを特徴とする汚染土壌の浄化方法である。
第４の態様では、前記水洗浄工程は、５０℃以上の温水を使用することで、油状物質の粘性を低下させ、土壌粒子からの分離を促すことができる。 According to a fourth aspect of the present invention, there is provided the method for purifying contaminated soil according to any one of the first to third aspects, wherein the water washing step uses hot water of 50 ° C. or higher. .
In the fourth aspect, the water washing step can use hot water of 50 ° C. or higher to reduce the viscosity of the oily substance and promote separation from soil particles.

また、本発明の第５の態様は、第１の態様乃至第４の態様のいずれかにおいて、前記スラリー化工程でスラリー化に用いる水は５０℃以上の温水を使用することを特徴とする、汚染土壌の浄化方法である。
このように、前記スラリー化工程で温水を使用することにより、油状物質の粘性が低下し、土壌粒子から遊離しやすくなる。 Further, a fifth aspect of the present invention is characterized in that in any one of the first aspect to the fourth aspect, the water used for the slurrying in the slurrying step uses hot water of 50 ° C. or more. It is a purification method for contaminated soil.
Thus, by using warm water in the slurrying step, the viscosity of the oily substance is lowered and is easily released from the soil particles.

また、本発明の第６の態様は、第２の態様乃至第５の態様のいずれかにおいて、前記撹拌工程はスラリー温度を５０℃以上に維持した状態で行うことを特徴とする、汚染土壌の浄化方法である。
第６の態様では、前記撹拌工程はスラリー温度を５０℃以上に維持した状態で行うことで、微粉状炭化物の粒子と油状物質へのせん断活性面の形成が効果的となる。 Further, a sixth aspect of the present invention is the contaminated soil according to any one of the second to fifth aspects, characterized in that the stirring step is performed in a state where the slurry temperature is maintained at 50 ° C. or higher. It is a purification method.
In the sixth aspect, the agitation step is performed in a state where the slurry temperature is maintained at 50 ° C. or more, so that formation of a shear active surface on the finely divided carbide particles and the oily substance becomes effective.

また、本発明の第７の態様は、第２の態様乃至第６の態様のいずれかにおいて、前記撹拌工程はスラリーに分級処理をして選別された平均粒径が０．５ｍｍ以下のスラリー区分に対して行うことを特徴とする、汚染土壌の浄化方法である。   Further, according to a seventh aspect of the present invention, in any one of the second aspect to the sixth aspect, the stirring step is a slurry classification in which an average particle size selected by classifying the slurry is 0.5 mm or less. A method for purifying contaminated soil, characterized in that

一般に、平均粒径が０.５ｍｍを超える土壌粒子は、微細粒子に比べて相対的に比表面積が小さくなり、油分が分離しやすい傾向がある。このため、乾式混練と温水スラリー化によって油分が除去されていることが多い。すなわち、高せん断力下での撹拌を行わなくても、分級すればそのまま水洗浄を施すだけで浄化できる場合が多い。
第７の態様では、高せん断力下での撹拌を行う対象土壌を粒径の大きな土壌部分は除いた残りの平均粒径が０．５ｍｍ以下の土壌としたので、撹拌処理量が少量化され、撹拌機を小型化することができる。 In general, soil particles having an average particle size exceeding 0.5 mm have a relatively small specific surface area compared to fine particles, and oil components tend to be separated. For this reason, oil is often removed by dry kneading and hot water slurrying. That is, even if stirring is not performed under a high shearing force, it can often be purified by simply washing with water if classified.
In the seventh aspect, the target soil to be agitated under high shear force is the soil having a remaining average particle size of 0.5 mm or less excluding the soil portion having a large particle size, so that the amount of agitation treatment is reduced. The agitator can be reduced in size.

本発明方法によれば、石油系油分などの油状物質で汚染された土壌から油状物質を効率よく分離し、土壌を浄化できる。   According to the method of the present invention, the oily substance can be efficiently separated from the soil contaminated with the oily substance such as petroleum oil, and the soil can be purified.

以下、適宜図面を参照しながら本発明の実施の形態について説明する。
図１は、本発明方法の基本的な工程を示すフロー図である。本発明による汚染土壌の浄化方法は、水洗浄工程１１と、スラリー化工程１２と、炭化物回収工程１４とを含む一連の工程により実施される。また、必要に応じて、前記炭化物回収工程の前に、図１中、破線で示す攪拌工程１３を設けることができる。 Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate.
FIG. 1 is a flowchart showing the basic steps of the method of the present invention. The method for purifying contaminated soil according to the present invention is carried out by a series of steps including a water washing step 11, a slurrying step 12, and a carbide recovery step 14. Moreover, the stirring process 13 shown with a broken line in FIG. 1 can be provided before the said carbide | carbonized_material collection | recovery process as needed.

本発明の浄化方法で処理対象となる汚染土壌としては、油状物質が混在した油汚染土壌であれば特に制限はない。ここで、汚染原因である油状物質は、特に限定されるものではなく、例えば、タール状またはオイル状の液状油などに代表される石油系の油分や炭化水素類のほか、食品廃油などの植物性の油や、工業廃油等が対象となる。なお、油状物質とともに、親油性の有害物質としてダイオキシン類やＰＣＢ類に代表される芳香族有機ハロゲン化合物、残留農薬などが存在する汚染土壌についても適用可能である。   The contaminated soil to be treated by the purification method of the present invention is not particularly limited as long as it is oil-contaminated soil mixed with oily substances. Here, the oily substance that causes contamination is not particularly limited. For example, in addition to petroleum-based oils and hydrocarbons represented by tar-like or oil-like liquid oil, plants such as food waste oil are used. Natural oil, industrial waste oil, and the like. In addition to oily substances, the present invention can also be applied to contaminated soil in which aromatic organic halogen compounds typified by dioxins and PCBs, residual agricultural chemicals, and the like exist as lipophilic harmful substances.

水洗浄工程１１では、汚染土壌に水を加えて攪拌し、浮上する油分を水とともに土壌から分離する。洗浄に際しては、攪拌装置などを用いて１〜５分間程度土壌と水を充分に混合し、油分の分離を促す。この操作により、油状物質の中で浮上し易いタール分やオイル分などを浮上せしめ、水とともに土壌から分離できる。その結果、後のスラリー化工程１２で添加する微粉状炭化物の量を減らすことが可能となり、処理効率が向上するとともにプロセスの経済性も高まる。   In the water washing step 11, water is added to the contaminated soil and stirred, and the oil component that rises is separated from the soil together with water. At the time of washing, the soil and water are sufficiently mixed for about 1 to 5 minutes using a stirrer or the like to promote separation of oil. By this operation, tar and oil that easily float in the oily substance can be lifted and separated from the soil together with water. As a result, it is possible to reduce the amount of finely divided carbide added in the subsequent slurrying step 12, improving the processing efficiency and increasing the economics of the process.

洗浄に用いる水は、汚染土壌の量に対して大過剰に使用することが好ましく、また、例えば５０℃〜９０℃程度の範囲の温水を使用することが好ましい。温水を使用することにより、油状物質の粘性が低下し、土壌粒子から遊離しやすくなる。   The water used for washing is preferably used in a large excess with respect to the amount of contaminated soil, and for example, warm water in the range of about 50 ° C. to 90 ° C. is preferably used. By using warm water, the viscosity of the oily substance is reduced and it is easily released from the soil particles.

浮上した油分を含む水は、必要に応じて油水分離装置などを使用して油分を分離回収した後、排水処理等を施すことによって放流できる。また、油分を分離後の水を洗浄水として水洗浄工程１１において循環利用することも可能である。   The water containing the floating oil component can be discharged by performing drainage treatment or the like after separating and recovering the oil component using an oil / water separator as required. It is also possible to circulate and use the water after separating the oil in the water washing step 11 as washing water.

スラリー化工程１２は、水洗浄した土壌に微粉状炭化物と水を加えてスラリーを調製する工程である。好ましくは、前記汚染土壌と微粉状炭化物と水を混合し、攪拌機などを用いて１〜５分間程度混合攪拌を実施する。ここで添加する微粉状炭化物は、炭化物を微粉砕等して得られる微細粒子である。炭化物としては、例えば、石炭や、木材チップなどのバイオマス由来の炭化物、熱分解カーボン、活性炭などが挙げられる。炭化物は、完全に炭化が進行したものよりも、炭化の程度が低く、少なくとも表面の物性として疎水性を有する炭化物が好ましい。この目的のため、例えばバイオマスを原料とする炭化物では、その調製に際し、５００℃前後の低温で炭化させたものが好ましい。また、任意的な物性として、炭化物はある程度の吸着性能も併せ持つことが好ましい。   The slurrying step 12 is a step of preparing a slurry by adding fine powdered carbide and water to the water-washed soil. Preferably, the contaminated soil, fine powdered carbide, and water are mixed and mixed and stirred for about 1 to 5 minutes using a stirrer or the like. The fine powder carbide added here is fine particles obtained by finely pulverizing the carbide. Examples of the carbide include coal and biomass-derived carbides such as wood chips, pyrolytic carbon, and activated carbon. The carbide is preferably a carbide having a lower degree of carbonization and at least a hydrophobic surface property than that in which carbonization has completely progressed. For this purpose, for example, a carbide using biomass as a raw material is preferably carbonized at a low temperature of around 500 ° C. in the preparation. Further, as an optional physical property, it is preferable that the carbide also has a certain degree of adsorption performance.

微粉状炭化物の平均粒径は、以下の範囲に限定されるものではないが、例えば０．５ｍｍ以下が好ましく、０．０５〜０．１５ｍｍの範囲がより好ましい。０．５ｍｍ以下に微粉砕した炭化物を用いることにより、一般の土壌粒子と同等以上の表面積を持つことになり、油状物質の添着性能が良好になる。   The average particle size of the fine powdered carbide is not limited to the following range, but is preferably 0.5 mm or less, and more preferably 0.05 to 0.15 mm. By using the carbide finely pulverized to 0.5 mm or less, it has a surface area equal to or larger than that of general soil particles, and the oily substance can be attached with better performance.

スラリー化工程１２における微粉状炭化物と水との添加順序は特に問われないが、微粉状炭化物を先に添加して混練などの操作を行った後で水を添加する場合、油状物質が土壌粒子から分離され易くなる効果が期待できる。すなわち、水が少ない又はほとんど存在しない状態では、汚染土壌中の油状物質と微粉状炭化物との接触が十分に起こり、その後のスラリー中で土壌粒子に付着した油状物質の乖離と親油性の微粉状炭化物への添着を速やかに進行させ得る。   The order of addition of the fine powdered carbide and water in the slurrying step 12 is not particularly limited. However, when water is added after the operation such as kneading by adding the fine powdered carbide first, the oily substance becomes soil particles. The effect which becomes easy to isolate | separate from can be expected. That is, in a state where there is little or almost no water, the contact between the oily substance in the contaminated soil and the fine powdered carbide occurs sufficiently, and the separation of the oily substance adhering to the soil particles and the lipophilic fine powdery form in the subsequent slurry. The attachment to the carbide can proceed promptly.

水スラリーにおける固形分濃度は、例えば３〜５０重量％程度、好ましくは２０〜３０％に調整する。水スラリー中の固形分濃度が少なすぎると、後段の攪拌工程で炭化物に十分なせん断力を与えることができず、逆に固形分濃度が多すぎると、攪拌が困難になる場合がある。   The solid content concentration in the water slurry is adjusted to, for example, about 3 to 50% by weight, preferably 20 to 30%. If the solid content concentration in the water slurry is too small, sufficient shearing force cannot be applied to the carbide in the subsequent stirring step. Conversely, if the solid content concentration is too high, stirring may be difficult.

スラリー化によって、水中に土壌粒子、油状物質および微粉状炭化物が分散した系が成立する。ここで、土壌粒子は無機物からなる親水性物質であり、微粉状炭化物は、前記したように疎水性（親油性）の表面物性を持つ。このため、油状物質は土壌粒子から、該土壌粒子よりも親和性の高い微粉状炭化物の方へ移行しやすくなる。   Slurry forms a system in which soil particles, oily substances and fine powdered carbides are dispersed in water. Here, the soil particles are a hydrophilic substance made of an inorganic substance, and the fine powdered carbide has a hydrophobic (lipophilic) surface property as described above. For this reason, the oily substance is easily transferred from the soil particles to fine powdered carbide having higher affinity than the soil particles.

スラリー化に用いる水は、例えば５０℃〜９０℃程度の範囲の温水を使用することが好ましい。温水を使用することにより、油状物質の粘性が低下し、土壌粒子から遊離しやすくなる。   The water used for slurrying is preferably warm water in the range of about 50 ° C. to 90 ° C., for example. By using warm water, the viscosity of the oily substance is reduced and it is easily released from the soil particles.

本発明方法の好ましい実施形態では、図１において破線で示すように、炭化物回収工程１４の前に攪拌工程１３を設けることができる。攪拌工程１３では、水スラリーに高せん断力を付与しながら攪拌を行う。この攪拌工程１３を設けることによって、土壌粒子と油状物質との分離を確実ならしめ、汚染土壌を高度に浄化することが可能になる。   In a preferred embodiment of the method of the present invention, a stirring step 13 can be provided before the carbide recovery step 14 as indicated by a broken line in FIG. In the stirring step 13, stirring is performed while applying a high shearing force to the water slurry. By providing this stirring step 13, it is possible to ensure separation of soil particles and oily substances and to highly purify contaminated soil.

攪拌工程１３では、スラリー化工程１２で得られるスラリーに、例えば２０〜２００ｋＷ／ｍ３程度（好ましくは３０〜８０ｋＷ／ｍ３程度）のせん断力が、３０秒〜５分程度（好ましくは３０秒〜９０秒程度）加わるようにすることが好ましい。せん断力が上記範囲よりも大き過ぎる場合、または上記範囲のせん断力でも攪拌時間が長すぎる場合には、高せん断攪拌機の大型化が必要となり、消費エネルギーも増大するが、それに見合うだけの効果の上昇は期待できないため、主として効率面で好ましくない。また、せん断力が上記範囲よりも小さ過ぎる場合、または上記範囲のせん断力でも攪拌時間が短すぎる場合には、微粉状炭化物への油状物質の添着（後述）が不十分となり、土壌浄化効果が低下する場合がある。 In the stirring step 13, the slurry obtained in the slurrying step 12 has a shearing force of, for example, about 20 to 200 kW / m 3 (preferably about 30 to 80 kW / m 3 ) for about 30 seconds to 5 minutes (preferably 30 seconds). It is preferable to add about 90 seconds). If the shearing force is too large than the above range, or if the stirring time is too long even in the above range, it is necessary to increase the size of the high shear stirrer and the energy consumption increases, but the effect is just enough to meet that. Since an increase cannot be expected, it is not preferable mainly in terms of efficiency. In addition, when the shearing force is too smaller than the above range, or when the stirring time is too short even with the shearing force within the above range, the oily substance is not sufficiently attached to the finely divided carbide (described later), and the soil purification effect is improved. May decrease.

また、高せん断力下での攪拌は、スラリー温度を前記と同様に５０℃〜９０℃程度に維持した状態で行うことが好ましい。これにより、微粉状炭化物の粒子と油状物質へのせん断活性面の形成が効果的となる。   Moreover, it is preferable to perform stirring under high shear force in a state where the slurry temperature is maintained at about 50 ° C. to 90 ° C. as described above. Thereby, the formation of the shear active surface on the finely divided carbide particles and the oily substance becomes effective.

攪拌工程１３で高せん断力を与える意義は、主として微粉状炭化物に表面改質（油添着）を起こさせることにある。ここで、攪拌工程１３における表面改質の機構について、図２を参照しながら詳説する。図２は、水スラリーの状態を模式的に示す図であり、同図（Ａ）は、前記したように水４中に土壌粒子１と油状物質２と微粉状炭化物３とが分散した状態を示している。なお、この段階では、汚染土壌中で土壌粒子１に付着していた油状物質２のすべてが油滴として遊離しているわけではない。   The significance of giving a high shearing force in the stirring step 13 is mainly to cause surface modification (oil addition) to fine powdered carbides. Here, the mechanism of surface modification in the stirring step 13 will be described in detail with reference to FIG. FIG. 2 is a diagram schematically showing the state of the water slurry. FIG. 2A shows the state in which the soil particles 1, the oily substance 2 and the finely divided carbide 3 are dispersed in the water 4 as described above. Show. At this stage, not all of the oily substance 2 attached to the soil particles 1 in the contaminated soil is released as oil droplets.

図２（Ａ）の状態の水スラリーにせん断力が加わると、同図（Ｂ）に示すように、水４中に油滴状態で遊離した油状物質２は、親水性の無機物質である土壌粒子１に比べ、より強い親和性を持つ親油性の微粉状炭化物３と会合し、その表面に薄膜状に添着する。この過程では、微粉状炭化物３の粒子と油状物質２にせん断活性面が形成され、このせん断活性面の発生により、過渡的現象として表面エネルギーの相対的上昇が起こり、微粉状炭化物３の表面に油状物質２の薄膜が形成されるものと考えられる。また、高せん断力攪拌によって、土壌粒子に付着していた油状物質２も次第に遊離し、親油性の微粉状炭化物３表面に移行していく。このようにして、一旦表面改質された微粉状炭化物３は、スラリー中に遊離してくる油状物質２をさらに引きつけ、これらをも融合させるように作用する。従って、汚染土壌中に、極めて微細な土壌粒子１（例えば平均粒径４５μｍ以下の土壌粒子１）が含まれている場合でも、油状物質２の分離が確実に行われる。   When a shearing force is applied to the water slurry in the state of FIG. 2A, the oily substance 2 released in the form of oil droplets in the water 4 is a soil that is a hydrophilic inorganic substance, as shown in FIG. It associates with the lipophilic fine powdered carbide 3 having a stronger affinity than the particles 1 and adheres to its surface in a thin film shape. In this process, a shear active surface is formed on the particles of finely divided carbide 3 and the oily substance 2, and the generation of this shear active surface causes a relative increase in surface energy as a transient phenomenon. It is thought that a thin film of oily substance 2 is formed. Moreover, the oily substance 2 adhering to the soil particles is gradually released by high shearing force stirring, and moves to the surface of the lipophilic fine powdered carbide 3. In this way, the finely powdered carbide 3 once surface-modified acts to further attract the oily substance 2 liberated in the slurry and fuse them together. Therefore, even when extremely fine soil particles 1 (for example, soil particles 1 having an average particle size of 45 μm or less) are contained in the contaminated soil, the oily substance 2 is reliably separated.

同図（Ｃ）は、後述する炭化物回収工程１４の状態を示しており、浮選を行うことにより、油状物質２は微粉状炭化物３の表面に付着した状態で気泡５とともに同伴し、土壌粒子１および水４から分離される。油添着された微粉状炭化物３は、疎水性がさらに強まり、気泡と同伴しやすい状態にあるから、土壌粒子１および水４との分離性能も格段に向上したものとなる。   FIG. 4C shows a state of a carbide recovery step 14 to be described later. By performing flotation, the oily substance 2 is accompanied with bubbles 5 in a state of adhering to the surface of the fine powdered carbide 3, and soil particles 1 and water 4. The oil-impregnated fine powdered carbide 3 is more hydrophobic and is likely to accompany bubbles, so that the separation performance from the soil particles 1 and water 4 is also greatly improved.

炭化物回収工程１４は、前記スラリー化工程１２または攪拌工程１３の後で実施され、浮選法によって炭化物の回収を行う工程である。浮選法は、選炭や選鉱などにおいて公知の方法であり、スラリー中に起泡剤を添加してバブリングを行い、微粉状炭化物を泡とともに浮上せしめ、フロスとして回収する。ここで起抱剤としては、例えばＭＩＢＣ（４−メチル−２−ペンタノール）、パイン油、テルピネオール、ポリオキシプロピレンアルキルエーテル、高級アルコールなどを用いることが可能であるが、これらの中でもＭＩＢＣが好ましい。   The carbide recovery step 14 is a step that is performed after the slurrying step 12 or the stirring step 13 and recovers the carbide by a flotation method. The flotation method is a well-known method in coal preparation, mineral processing, and the like, and a foaming agent is added to the slurry to perform bubbling, so that fine powdered carbides are floated together with bubbles and recovered as floss. Here, for example, MIBC (4-methyl-2-pentanol), pine oil, terpineol, polyoxypropylene alkyl ether, higher alcohol, and the like can be used, and among these, MIBC is preferable. .

浮選によって、気泡とともに浮上選別される微粉状炭化物には、油状物質が同伴するため、これを回収することによって、土壌および水から分離される。なお、乾式混練工程で油分を添加した場合には、該油分および有害物質も微粉状炭化物とともに土壌と分離されることになる。   Oily substances are entrained in fine powdered carbides that are floated and sorted together with bubbles by flotation, so that they are separated from soil and water by collecting them. When oil is added in the dry kneading process, the oil and harmful substances are separated from the soil together with the fine powdered carbide.

以上のようにして油状物質が分離された土壌粒子は、浮上せずに水中に残留することになる。この土壌を脱水処理することによって、浄化土壌が得られる。なお、浄化の度合いに応じ、土壌粒子中の粗粒分と細粒分とを分別し、細粒分についてはさらなる浄化処理を施すことも可能である。   The soil particles from which the oily substance is separated as described above remain in the water without floating. Purified soil can be obtained by dehydrating the soil. In addition, according to the degree of purification | cleaning, the coarse particle part and fine particle part in a soil particle can be fractionated, and it is also possible to perform a further purification process about a fine particle part.

図３は、本発明に係る汚染土壌の浄化方法を実施するためのシステムフローの典型例を示す図である。
まず、汚染土壌と温水を洗浄タンク２１に投入し、攪拌混合して洗浄を行う（水洗浄工程１１）。ここで油状物質中の浮上しやすい油分の大半が分離されるので、以降の処理において、例えば微粉状炭化物の添加量を節減したり、浮選処理の時間を短縮できるなど、プロセスへの負荷を大幅に低下できる。 FIG. 3 is a diagram showing a typical example of a system flow for carrying out the contaminated soil purification method according to the present invention.
First, contaminated soil and warm water are put into the washing tank 21 and mixed and stirred for washing (water washing step 11). Since most of the oil component that easily floats in the oily substance is separated here, in the subsequent processing, for example, the amount of finely divided carbide added can be reduced or the flotation processing time can be shortened. Can be greatly reduced.

洗浄タンク２１から排出された浮上油を含む洗浄水は、油水分離装置２３に移され、ここで水相と油相とに分離され、油分が回収される。水相は、排水処理を施すことにより放流するか、あるいは洗浄水として洗浄タンク２１へ循環させることが可能である。   The wash water containing the floating oil discharged from the wash tank 21 is transferred to the oil / water separator 23, where it is separated into a water phase and an oil phase, and the oil is recovered. The aqueous phase can be discharged by performing wastewater treatment or can be circulated to the cleaning tank 21 as cleaning water.

次に、洗浄後の土壌をスラリー調整槽２２に移し、ここで微粉状炭化物を添加するとともに、必要に応じて温水を追加して水スラリーを調製する（スラリー化工程１２）。その後、水スラリーを分級機２５にかけて篩い分けを行う。この篩い分け工程は任意である。一般に平均粒径が０.５ｍｍを超える土壌粒子は、微細粒子に比べて相対的に比表面積が小さくなり、油分が分離しやすい傾向がある。このため、水洗浄工程１１とスラリー化工程１２によって油分が除去されていることも多く、分級すればそのまま水洗浄を施すだけで浄化できる場合がある。   Next, the soil after washing is transferred to the slurry adjusting tank 22, where fine powdered carbide is added, and hot water is added as necessary to prepare a water slurry (slurry step 12). Thereafter, the water slurry is passed through a classifier 25 and sieved. This sieving step is optional. In general, soil particles having an average particle size exceeding 0.5 mm have a relatively small specific surface area as compared with fine particles, and oil tends to be easily separated. For this reason, the oil component is often removed by the water washing step 11 and the slurrying step 12, and if it is classified, it may be purified by simply washing with water.

篩い分けにより選別された０.５ｍｍ以下のスラリー区分（微細な土壌粒子と微粉状炭化物および油状物質を含む）は表面改質機２７に導入され、前記した条件で高せん断力下で攪拌が行われる（攪拌工程１３）。攪拌後のスラリーは一時的に調整槽２９に貯留され、ここで水分量の調整（水の添加）と起泡剤の添加が行われ、引き続き浮選機３１に移される。   Slurry sections of 0.5 mm or less (including fine soil particles, finely divided carbides and oily substances) selected by sieving are introduced into the surface reformer 27 and stirred under high shear force under the conditions described above. (Stirring step 13). The slurry after agitation is temporarily stored in the adjustment tank 29, where the amount of water is adjusted (addition of water) and the foaming agent is added, and subsequently transferred to the flotation machine 31.

浮選機３１では、浮選法による炭化物の選別がなされ、油状物質を吸着した炭化物はフロスとして分離される（炭化物回収工程１４）。このフロスは、必要に応じて脱水装置３３、乾燥装置３５で脱水処理、乾燥処理が施され、油状物質を吸着した状態の回収炭化物となる。   In the flotation machine 31, the carbide is selected by the flotation method, and the carbide adsorbing the oily substance is separated as floss (carbide recovery step 14). The floss is dehydrated and dried by a dehydrating device 33 and a drying device 35 as necessary, and becomes a recovered carbide in a state where an oily substance is adsorbed.

一方、浮選によって微粉状炭化物と油状物質が除去された土壌粒子のスラリーは、必要に応じて分級機４１において、例えば４５μｍ超の粒子と４５μｍ以下の粒子に区分される。篩い分けられた４５μｍ超の土壌粒子は、そのまま浄化土壌とすることができる。
４５μｍ以下の微細な土壌粒子は、水中に懸濁状態にあるため、シックナー４３において静置し、上清と沈澱物とに分離される。上清は、排水処理装置４５により排水処理が施され、放流される。沈澱物は脱水装置４７において脱水された後、油状物質の残留の有無を測定し、残留がなければ浄化土壌として回収される。 On the other hand, the slurry of the soil particles from which fine powdered carbides and oily substances have been removed by flotation is classified into particles of, for example, more than 45 μm and particles of less than 45 μm in the classifier 41 as necessary. The sieved soil particles of more than 45 μm can be used as purified soil as they are.
Since fine soil particles of 45 μm or less are in a suspended state in water, they are allowed to stand in the thickener 43 and separated into a supernatant and a precipitate. The supernatant is subjected to wastewater treatment by the wastewater treatment device 45 and discharged. After the precipitate is dehydrated in the dehydrator 47, the presence or absence of the oily substance is measured, and if there is no residue, it is recovered as purified soil.

以上において、分級機４１以後の操作は任意である。一般的に、微細な土壌粒子になるほど油状物質の分離が困難であることに鑑み、確認的にこの分別操作を行うことにより、浄化処理に確実を期することができる。   In the above, the operation after the classifier 41 is arbitrary. In general, in view of the fact that the separation of oily substances becomes more difficult as the soil particles become finer, it is possible to ensure the purification treatment by confirming this separation operation.

以下、実施例を挙げ、本発明をさらに詳しく説明するが、本発明はこれにより何ら制約されるものではない。
実施例１
以下の方法で汚染土壌の浄化を実施した。
汚染土壌１６０ｇ（含水率（湿潤土壌の水の質量／湿潤土の質量）：４０％以下）に８０℃の温水４００ｍｌを加えて撹拌し、浮上する油分を水と共に土壌から分離して水洗浄を行った。水洗浄工程後、油混じりの汚染土壌と微粉炭（平均粒径０．５ｍｍ以下）３０ｇを共にステンレス製容器内に投入し、約５分間混練した。混練の際、ステンレス製容器を約８０℃の湯せんによって外部から加温した。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by this.
Example 1
The contaminated soil was purified by the following method.
Add 400 ml of 80 ° C warm water to 160 g of contaminated soil (moisture content (mass of wet soil water / wet soil mass): 40% or less) and stir to separate the floating oil from the soil with water and wash it with water. went. After the water washing step, both contaminated soil mixed with oil and 30 g of pulverized coal (average particle size of 0.5 mm or less) were put into a stainless steel container and kneaded for about 5 minutes. During the kneading, the stainless steel container was heated from the outside with a hot water bath of about 80 ° C.

混練終了後、約８０℃の温水４００ｍｌを加え、スラリー化した。このスラリーを表面改質機Ｍ−ＣＯＬ（登録商標；三井造船株式会社製）に投入して、スラリー中の微粉炭および油状物質の表面を改質するために、高せん断力場での攪拌を１分間行った。攪拌中は、表面改質機内の温度が低下しないように外部ヒーターを使用して加温した（設定温度８０℃）。   After the kneading, 400 ml of warm water at about 80 ° C. was added to make a slurry. In order to modify the surface of the pulverized coal and oily substance in the slurry by introducing this slurry into a surface reformer M-COL (registered trademark; manufactured by Mitsui Engineering & Shipbuilding Co., Ltd.), stirring in a high shear force field is performed. For 1 minute. During stirring, heating was performed using an external heater so that the temperature inside the surface reformer did not decrease (set temperature: 80 ° C.).

次に、表面改質機の内容物をステンレス製容器に取り出し、水２２００ｍｌを加えてスラリー濃度を調整した後、起泡剤ＭＩＢＣを２滴添加し、浮選機に移した。浮選機では浮選法により微細空気とともに浮上してくるフロス（油状物質を吸着した炭化物）を約８分間掻き取り機で回収し、分離回収した。   Next, the contents of the surface reformer were taken out into a stainless steel container, and after adding 2200 ml of water to adjust the slurry concentration, two drops of the foaming agent MIBC were added and transferred to a flotation machine. In the flotation machine, floss (carbide adsorbed with oily substances) that floats with fine air by the flotation method was collected with a scraper for about 8 minutes and separated and collected.

浮選機中に残された土壌成分を（ア）０.５ｍｍ超、（イ）０．０４５ｍｍ超〜０.５ｍｍ以下、（ウ）０.０４５ｍｍ以下、の３区分に分級し、浄化土壌とした。各区分の浄化土壌について、ＴＰＨ（総石油炭化水素）含有量を測定した。また、温水洗浄のみを施した汚染土壌についても参考のため油除去率を測定した。これらの結果を表１に示す。   The soil components left in the flotation machine are classified into three categories: (A) over 0.5 mm, (I) over 0.045 mm to 0.5 mm or less, and (c) 0.045 mm or less. did. About the purified soil of each division, TPH (total petroleum hydrocarbon) content was measured. The oil removal rate was also measured for reference in contaminated soil that had been washed with warm water only. These results are shown in Table 1.

Figure 2005186057
表１から、いずれの粒径区分においても油除去率は９９％を超え、実用上極めて優れた浄化性能が得られることが確認された。なお、温水洗浄を施しただけの汚染土壌でも、油除去率は８０％を超える結果が示された。このことから、水洗浄工程を設け油の一部を除去しておくことによって、引き続く各工程における負荷が大幅に軽減され、粒径にかかわらず高い浄化性能が得られたものと考えられる。
Figure 2005186057
 From Table 1, it was confirmed that the oil removal rate exceeded 99% in any particle size classification, and extremely excellent purification performance was obtained in practical use. In addition, the result of oil removal rate exceeding 80% was shown even in the contaminated soil that was just washed with warm water. From this, it is considered that by providing a water washing step and removing part of the oil, the load in each subsequent step is greatly reduced, and high purification performance is obtained regardless of the particle size.

実施例２
本実施例は表面改質機Ｍ−ＣＯＬを使用しない場合についてのものである。以下の方法で汚染土壌の浄化を実施した。
汚染土壌１６０ｇ（含水率（湿潤土壌の水の質量／湿潤土の質量）：４０％以下）に８０℃の温水４００ｍｌを加えて撹拌し、浮上する油分を水と共に土壌から分離して水洗浄を行った。水洗浄工程後、油混じりの汚染土壌と微粉炭（平均粒径０．５ｍｍ以下）３０ｇを共にステンレス製容器内に投入し、約５分間混練した。混練の際、ステンレス製容器を約８０℃の湯せんによって外部から加温した。 Example 2
In this embodiment, the surface reformer M-COL is not used. The contaminated soil was purified by the following method.
Add 400 ml of 80 ° C warm water to 160 g of contaminated soil (moisture content (mass of wet soil water / wet soil mass): 40% or less) and stir to separate the floating oil from the soil with water and wash it with water. went. After the water washing step, both contaminated soil mixed with oil and 30 g of pulverized coal (average particle size of 0.5 mm or less) were put into a stainless steel container and kneaded for about 5 minutes. During the kneading, the stainless steel container was heated from the outside with a hot water bath of about 80 ° C.

混練終了後、約８０℃の温水４００ｍｌを加え、スラリー化した。このスラリーを高せん断力場にならない撹拌力の撹拌装置で攪拌を１分間行った。攪拌中は、撹拌装置内の温度が低下しないように外部ヒーターを使用して加温した（設定温度８０℃）。   After the kneading, 400 ml of warm water at about 80 ° C. was added to make a slurry. The slurry was stirred for 1 minute with a stirring device having a stirring force that did not result in a high shear force field. During stirring, heating was performed using an external heater so that the temperature in the stirring device did not decrease (set temperature 80 ° C.).

次に、撹拌装置の内容物をステンレス製容器に取り出し、水２２００ｍｌを加えてスラリー濃度を調整した後、起泡剤ＭＩＢＣを２滴添加し、浮選機に移した。浮選機では浮選法により微細空気とともに浮上してくるフロス（油状物質を吸着した炭化物）を約８分間掻き取り機で回収し、分離回収した。   Next, the content of the stirring device was taken out into a stainless steel container, and after adding 2200 ml of water to adjust the slurry concentration, 2 drops of foaming agent MIBC was added and transferred to a flotation machine. In the flotation machine, floss (carbide adsorbed with oily substances) that floats with fine air by the flotation method was collected with a scraper for about 8 minutes and separated and collected.

浮選機中に残された土壌成分を粒径で（ア）０.５ｍｍ超、（イ）０．０４５ｍｍ超〜０.５ｍｍ以下、（ウ）０.０４５ｍｍ以下、の３区分に分級し、浄化土壌とした。各区分の浄化土壌について、ＴＰＨ含有量を測定した。また、温水洗浄のみを施した汚染土壌についても参考のため油除去率を測定した。これらの結果を表２に示す。   The soil components left in the flotation machine are classified into three categories: (a) greater than 0.5 mm, (b) greater than 0.045 mm to less than 0.5 mm, and (c) less than 0.045 mm. Purified soil. About the purified soil of each division, TPH content was measured. The oil removal rate was also measured for reference in contaminated soil that had been washed with warm water only. These results are shown in Table 2.

Figure 2005186057
本発明における水洗浄工程を経ることで、高せん断力場での攪拌を行わなくても、粒径０．０４５ｍｍ以上の土壌に対して、実用上十分な浄化性能が得られることが確認された。実施例１との対比から、粒径０．０４５ｍｍ以下の土壌については、表面改質機Ｍ−ＣＯＬによって高せん断力撹拌を行うことで、十分な浄化が行えることが理解できる。この粒径の土壌だけを分級して選別し、それを上記表面改質機Ｍ−ＣＯＬで高せん断力撹拌処理することで、当該改質機の容量を小規模化することが可能になる。
Figure 2005186057
 Through the water washing step in the present invention, it was confirmed that practically sufficient purification performance could be obtained for soil having a particle size of 0.045 mm or more without stirring in a high shear force field. . From comparison with Example 1, it can be understood that the soil having a particle size of 0.045 mm or less can be sufficiently purified by stirring with a high shear force by the surface reformer M-COL. Only the soil with this particle size is classified and selected, and it is subjected to a high shearing force stirring process with the surface reformer M-COL, whereby the capacity of the reformer can be reduced.

比較例１
比較例１は、従来技術である特許第２８４６４６号公報に記載されている処理方法と同様の場合についてのものである。具体的には以下の方法で汚染土壌の浄化を実施した。
原油採掘現場で採取された汚染土壌１６０ｇ（含水率：４０％以下）に温水（温度６０℃）を４００ｍｌ加え、スラリー化した。スラリー化後、微粉炭（平均粒径０．５ｍｍ以下）３０ｇと共に混転機に投入して、５分間混転した。混転終了後、（ア）０．５ｍｍ超の粒径のもののみ分級した。 Comparative Example 1
Comparative Example 1 is for the case similar to the processing method described in Japanese Patent No. 284646, which is a prior art. Specifically, the contaminated soil was purified by the following method.
400 ml of warm water (temperature 60 ° C.) was added to 160 g of contaminated soil (water content: 40% or less) collected at a crude oil mining site to form a slurry. After slurrying, 30 g of pulverized coal (average particle size of 0.5 mm or less) was added to the mixer and tumbled for 5 minutes. After completion of the tumbling, (a) only those having a particle size of more than 0.5 mm were classified.

０．５ｍｍ以下の土壌については高せん断力攪拌機で、２分間高せん断力撹拌を行った。攪拌中は、高せん断力攪拌機内の温度が低下しないように、外部ヒーターを使用して加温した（設定温度６０℃）。   About the soil of 0.5 mm or less, high shear force stirring was performed for 2 minutes with the high shear force stirrer. During stirring, heating was performed using an external heater so that the temperature in the high shearing stirrer did not decrease (set temperature 60 ° C.).

次に、高せん断力攪拌機の内容物をステンレス製容器に取り出し、水２２００ｍｌを加えてスラリー濃度を調整した後、起泡剤ＭＩＢＣを２滴添加し、浮選機に移した。浮選機では浮選法により微細空気とともに浮上してくるフロス（油状物質を吸着した炭化物）を約８分間掻き取り機で回収し、分離回収した。   Next, the contents of the high shearing stirrer were taken out into a stainless steel container, and after adding 2200 ml of water to adjust the slurry concentration, 2 drops of foaming agent MIBC were added and transferred to a flotation machine. In the flotation machine, floss (carbide adsorbed with oily substances) that floats with fine air by the flotation method was collected with a scraper for about 8 minutes and separated and collected.

浮選機中に残された土壌成分を、（イ）０．０４５ｍｍ超〜０.５ｍｍ以下、（ウ）０.０４５ｍｍ以下、の２区分に分級した。各区分の浄化土壌について、ＴＰＨ含有量を測定した。その結果を表３に示す。   The soil components left in the flotation machine were classified into two categories: (ii) greater than 0.045 mm to 0.5 mm or less, and (iii) 0.045 mm or less. About the purified soil of each division, TPH content was measured. The results are shown in Table 3.

Figure 2005186057
比較例１では、本発明における水洗浄工程を経ないため、十分な浄化性能が得られない。表３において、浄化後の粒径０．５ｍｍ超のＴＰＨ濃度が浄化前のＴＰＨ濃度より高い理由は以下の通りである。
一般的に、粗粒土壌に比べて細粒土壌に油状物質が高濃度に吸着している。水洗後及び高せん断力撹拌によって前記土壌から油状物質が遊離し、微粉状炭化物に添着及びスラリー中の遊離油状物質も融合一体化するが、微粉状炭化物よりも大きい土壌粒子については、微粉状炭化物との接触回数が少なく、かつ微粉状炭化物の接触回数が少ないためスラリー中に遊離した油状物質が当該土壌粒子に吸着し、浄化前よりも汚染濃度が高くなったと考えられる。
Figure 2005186057
 In Comparative Example 1, since the water washing process in the present invention is not performed, sufficient purification performance cannot be obtained. In Table 3, the reason why the TPH concentration with a particle size of more than 0.5 mm after purification is higher than the TPH concentration before purification is as follows.
In general, oily substances are adsorbed at a higher concentration in fine-grained soil than in coarse-grained soil. After washing with water and stirring with high shear force, oily substances are released from the soil, and the oily substances attached to the slurry and the free oily substances in the slurry are fused and integrated. However, for soil particles larger than the fine powdered carbides, It is considered that the oily substance released in the slurry was adsorbed on the soil particles and the contamination concentration was higher than before the purification because the number of contact with the soil was small and the number of contact with the fine powdered carbide was small.

実施例３
実施例３はダイオキシン類で汚染された土壌に対する浄化実験である。
（１）先ず、ダイオキシン物質については、ダイオキシン類を直接使用することは難しいため、ダイオキシン類と似たような疎水性を有するジベンゾフランを代替物質として使用し、当該実験を行った。
（２）模擬汚染土壌として、園芸で使用されている川砂と黒砂を６：４の割合で混ぜて、土壌量を１５０ｇに調整した。そして、ジベンゾフラン０．５ｇを無水エタノール１０ｍｌに溶解し、それを前記土壌と混合し、振とう後、風化させ模擬汚染土壌とした。 Example 3
Example 3 is a purification experiment on soil contaminated with dioxins.
(1) First, for dioxin substances, since dioxins are difficult to use directly, dibenzofuran having hydrophobicity similar to that of dioxins was used as an alternative substance, and the experiment was conducted.
(2) As simulated contaminated soil, river sand and black sand used in horticulture were mixed at a ratio of 6: 4 to adjust the amount of soil to 150 g. Then, 0.5 g of dibenzofuran was dissolved in 10 ml of absolute ethanol, mixed with the soil, shaken and weathered to obtain simulated contaminated soil.

（３）実験方法
前記模擬汚染土壌に水１００ｍｌとＣ重油５ｍｌを加えて、汚染土壌の撹拌洗浄を５分間実施した。更に浮上する油分を分離した。その後、それに微粉炭（平均粒径０．５ｍｍ以下）を２５ｇ加えて、更に５分間撹拌した。
撹拌後、スラリー濃度を調整するために水３００ｍｌを加え、表面改質機Ｍ−ＣＯＬに投入して、スラリー中の微粉炭および油状物質の表面を改質するために、高せん断力場での撹拌を３０秒間行った。
次に、表面改質機の内容物をステンレス製容器に取り出し、水２２００ｍｌを加えてスラリー濃度を調整した後、起泡剤ＭＩＢＣを２滴添加して、浮選機に移した。浮選機では浮選法により微細空気とともに浮上してくるフロス（ダイオキシン代替物質を吸着した炭化物）を１０分間掻き取り機で回収し、分離回収した。
浮選機中に残された土壌成分を粒径で（ア）０.５ｍｍ超、（イ）０．０７４ｍｍ超〜０.５ｍｍ以下、（ウ）０.０７４ｍｍ以下、の３区分に分級した。各区分の土壌について、ジベンゾフラン含有量を測定した。その結果を表４に示す。 (3) Experimental method 100 ml of water and 5 ml of C heavy oil were added to the simulated contaminated soil, and the contaminated soil was stirred and washed for 5 minutes. Further, the floating oil was separated. Thereafter, 25 g of pulverized coal (average particle size of 0.5 mm or less) was added thereto and further stirred for 5 minutes.
After stirring, 300 ml of water is added to adjust the slurry concentration, and it is put into the surface reformer M-COL to improve the surface of the pulverized coal and oily substance in the slurry. Stirring was performed for 30 seconds.
Next, the contents of the surface reformer were taken out into a stainless steel container, and after adding 2200 ml of water to adjust the slurry concentration, 2 drops of foaming agent MIBC was added and transferred to a flotation machine. In the flotation machine, floss (carbide adsorbing a dioxin substitute substance) that floated with fine air by the flotation method was recovered with a scraper for 10 minutes and separated and recovered.
The soil components left in the flotation machine were classified into three categories: (a) more than 0.5 mm, (b) more than 0.074 mm to 0.5 mm or less, and (c) 0.074 mm or less. Dibenzofuran content was measured for each category of soil. The results are shown in Table 4.

Figure 2005186057
親油性の有害物質であるダイオキシン類に代表される芳香族有機ハロゲン化合物による汚染土壌に対しても、当該プロセスは有効であることが確認された。
Figure 2005186057
 It was confirmed that the process is effective even for soil contaminated with aromatic organic halogen compounds represented by dioxins, which are lipophilic harmful substances.

以上、本発明を種々の実施形態に関して述べたが、本発明は上記実施形態に制約されるものではなく、特許請求の範囲に記載された発明の範囲内で、他の実施形態についても適用可能である。   The present invention has been described above with reference to various embodiments. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments within the scope of the invention described in the claims. It is.

本発明方法は、石油系油状物質などに汚染された土壌の浄化に利用できる。   The method of the present invention can be used for purification of soil contaminated with petroleum oily substances.

本発明に係る土壌の浄化方法の概要を示すフロー図である。It is a flowchart which shows the outline | summary of the purification method of the soil which concerns on this invention. 微粉状炭化物の表面改質の説明に供する原理図である。It is a principle figure with which it uses for description of surface modification of a fine powder carbide. 本発明方法を実施するための代表的なシステムフロー図である。FIG. 2 is a typical system flow diagram for carrying out the method of the present invention.

符号の説明Explanation of symbols

１ 土壌粒子
２ 油状物質
３ 微粉状石炭
４ 水
５ 気泡
１１ 水洗浄工程
１２ スラリー化工程
１３ 攪拌工程
１４ 炭化物回収工程
２１ 洗浄タンク
２２ スラリー調整槽
２３ 油水分離装置
２５ 分級機
２７ 表面改質機
２９ 調整槽
３１ 浮選機
３３ 脱水装置
３５ 乾燥装置
４１ 分級機
４３ シックナー
４５ 排水処理装置
４７ 脱水装置 DESCRIPTION OF SYMBOLS 1 Soil particle 2 Oily substance 3 Fine powder coal 4 Water 5 Bubble 11 Water washing process 12 Slurry process 13 Stirring process 14 Carbide recovery process 21 Washing tank 22 Slurry adjustment tank 23 Oil water separator 25 Classifier 27 Surface reformer 29 Adjustment Tank 31 Flotation machine 33 Dehydrating device 35 Drying device 41 Classifier 43 Thickener 45 Wastewater treatment device 47 Dehydrating device

Claims (7)

油状物質で汚染された土壌から該油状物質を分離して土壌を浄化する汚染土壌の浄化方法であって、
汚染土壌に水を加えて攪拌し、浮上する油分を水とともに土壌から分離する水洗浄工程と、
水洗浄後の土壌に水と微粉状炭化物を加えてスラリーを調製するスラリー化工程と、
前記スラリー中の微粉状炭化物を浮選によって回収する炭化物回収工程と、
を含むことを特徴とする、汚染土壌の浄化方法。 A method for purifying contaminated soil, wherein the soil is purified by separating the oily substance from soil contaminated with the oily substance,
Water washing step of adding water to the contaminated soil, stirring, separating the floating oil from the soil with water,
A slurrying step of preparing a slurry by adding water and fine powdered carbide to the soil after water washing;
A carbide recovery step of recovering fine powdered carbide in the slurry by flotation;
A method for purifying contaminated soil, comprising: 請求項１において、前記炭化物回収工程の前に、前記スラリーにせん断力を加えて攪拌する攪拌工程を設けたことを特徴とする、汚染土壌の浄化方法。   2. The method for purifying contaminated soil according to claim 1, further comprising a stirring step in which a shearing force is applied to the slurry to stir the slurry before the carbide recovery step. 請求項１または請求項２において、前記スラリー化工程は、水洗浄後の土壌に微粉状炭化物を加えて混練した後、水を加えてスラリー化するものであることを特徴とする、汚染土壌の浄化方法。   3. The contaminated soil according to claim 1, wherein in the slurrying step, the finely ground carbide is added to the soil after washing with water and kneaded, and then water is added to form a slurry. Purification method. 請求項１から３のいずれか１項において、前記水洗浄工程は、５０℃以上の温水を使用することを特徴とする、汚染土壌の浄化方法。   The method for purifying contaminated soil according to any one of claims 1 to 3, wherein the water washing step uses hot water of 50 ° C or higher. 請求項１から４のいずれか１項において、前記スラリー化工程でスラリー化に用いる水は５０℃以上の温水を使用することを特徴とする、汚染土壌の浄化方法。   5. The method for purifying contaminated soil according to claim 1, wherein the water used for slurrying in the slurrying step is warm water of 50 ° C. or higher. 請求項２から５のいずれか１項において、前記撹拌工程はスラリー温度を５０℃以上に維持した状態で行うことを特徴とする、汚染土壌の浄化方法。   The method for purifying contaminated soil according to any one of claims 2 to 5, wherein the stirring step is performed in a state where the slurry temperature is maintained at 50 ° C or higher. 請求項２から６のいずれか１項において、前記撹拌工程はスラリーに分級処理をして選別された平均粒径が０．５ｍｍ以下のスラリー区分に対して行うことを特徴とする、汚染土壌の浄化方法。   7. The contaminated soil according to claim 2, wherein the agitation step is performed on a slurry section having an average particle size of 0.5 mm or less selected by classifying the slurry. Purification method.
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