JP4745955B2 - Hexavalent chromium elution inhibitor - Google Patents
Hexavalent chromium elution inhibitor Download PDFInfo
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- JP4745955B2 JP4745955B2 JP2006345313A JP2006345313A JP4745955B2 JP 4745955 B2 JP4745955 B2 JP 4745955B2 JP 2006345313 A JP2006345313 A JP 2006345313A JP 2006345313 A JP2006345313 A JP 2006345313A JP 4745955 B2 JP4745955 B2 JP 4745955B2
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- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 title claims description 62
- 238000010828 elution Methods 0.000 title claims description 53
- 239000003112 inhibitor Substances 0.000 title claims description 10
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 30
- 239000000395 magnesium oxide Substances 0.000 claims description 26
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 26
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 26
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 14
- RCIVOBGSMSSVTR-UHFFFAOYSA-L stannous sulfate Chemical compound [SnH2+2].[O-]S([O-])(=O)=O RCIVOBGSMSSVTR-UHFFFAOYSA-L 0.000 claims description 12
- 229910000375 tin(II) sulfate Inorganic materials 0.000 claims description 12
- 230000001629 suppression Effects 0.000 claims description 7
- 239000002689 soil Substances 0.000 description 39
- 238000000034 method Methods 0.000 description 19
- 238000002156 mixing Methods 0.000 description 18
- 239000000463 material Substances 0.000 description 16
- 239000000843 powder Substances 0.000 description 15
- 235000010216 calcium carbonate Nutrition 0.000 description 14
- 230000000694 effects Effects 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 239000002245 particle Substances 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000007711 solidification Methods 0.000 description 6
- 230000008023 solidification Effects 0.000 description 6
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 5
- 239000001095 magnesium carbonate Substances 0.000 description 5
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 5
- 235000019738 Limestone Nutrition 0.000 description 4
- 239000003153 chemical reaction reagent Substances 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
- 239000006028 limestone Substances 0.000 description 4
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 4
- 239000000347 magnesium hydroxide Substances 0.000 description 4
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 238000012669 compression test Methods 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 229940031958 magnesium carbonate hydroxide Drugs 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000012790 confirmation Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241000242757 Anthozoa Species 0.000 description 1
- 235000014653 Carica parviflora Nutrition 0.000 description 1
- KSPIHGBHKVISFI-UHFFFAOYSA-N Diphenylcarbazide Chemical compound C=1C=CC=CC=1NNC(=O)NNC1=CC=CC=C1 KSPIHGBHKVISFI-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 210000004556 brain Anatomy 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000005802 health problem Effects 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 238000013008 moisture curing Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- FAKFSJNVVCGEEI-UHFFFAOYSA-J tin(4+);disulfate Chemical compound [Sn+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O FAKFSJNVVCGEEI-UHFFFAOYSA-J 0.000 description 1
Description
本発明は、酸化マグネシウム及び硫酸第一錫を含む６価クロムの溶出抑制材に関する。 The present invention relates to the elution suppressor hexavalent chromium containing magnesium oxide and stannous sulfate.
近年、工場・事業所や産業廃棄物処理場などの跡地の土壌が６価クロムで汚染されていることがしばしば報告されている。土壌が６価クロムで汚染されると、地下水も汚染されて、人体に影響を及ぼすという安全衛生上の問題のみならず、汚染濃度が環境基準値を超える場合には、跡地をそのまま利用できなくなり、土地の有効利用の妨げとなる。土壌 に６価クロムが含まれている跡地を有効活用するためにも、土壌から６価クロムが溶出するのを抑制・防止する方法が望まれている。 In recent years, it has often been reported that soils of former sites such as factories / business establishments and industrial waste treatment plants are contaminated with hexavalent chromium. When soil is contaminated with hexavalent chromium, groundwater is also contaminated, causing not only safety and health problems that affect the human body, but if the contamination concentration exceeds the environmental standard value, the site cannot be used as it is. This hinders effective use of land. In order to effectively utilize the site where hexavalent chromium is contained in the soil, a method for suppressing / preventing the elution of hexavalent chromium from the soil is desired.
従来、６価クロムに汚染された土壌に、酸化マグネシウムを添加して、６価クロムの溶出を抑制する方法が提案されている（特許文献１、２）。
また、６価クロムに汚染された土壌に、酸化カルシウム、酸化マグネシウム及びそれらの前駆物質からなる群から選ばれた少なくとも一種のアルカリ性物質を添加した後に、これを酸素含有率2.5％以下の雰囲気ガスと接触させながら500〜1000℃の範囲内の処理温度で処理し、６価クロムを無害化する方法も提案されている（特許文献３）。
Further, after adding at least one alkaline substance selected from the group consisting of calcium oxide, magnesium oxide and their precursors to the soil contaminated with hexavalent chromium, this is added to an atmospheric gas having an oxygen content of 2.5% or less. A method of detoxifying hexavalent chromium by treating at a treatment temperature within a range of 500 to 1000 ° C. while being brought into contact therewith has also been proposed (Patent Document 3).
上記特許文献１、２に記載されるように、６価クロムに汚染された土壌に、酸化マグネシウムを添加する方法では、６価クロム溶出量が比較的少ない土壌に関しては、６価クロムの溶出を抑制することは可能であるが、６価クロム溶出量が多い土壌に関しては、６価クロムの溶出を抑制するために添加量が増加し、コストが高くなるとともに混合後のボリュームも増加することで副次的な対策が必要となる場合がある。
上記特許文献３に記載される方法では、６価クロム溶出量が多い土壌に関しても無害化することは可能であるが、酸素含有率2.5％以下の雰囲気ガスと接触させながら500〜1000℃の範囲で加熱処理する必要があるので、土壌を原位置で処理することは不可能であるという問題がある。
As described in Patent Documents 1 and 2 above, in the method of adding magnesium oxide to soil contaminated with hexavalent chromium, elution of hexavalent chromium is performed on soil with a relatively small amount of hexavalent chromium elution. It is possible to suppress, but for soil with a large amount of hexavalent chromium elution, the amount added increases to suppress the elution of hexavalent chromium, which increases costs and increases the volume after mixing. Secondary measures may be required.
In the method described in Patent Document 3, it is possible to detoxify soil with a large amount of hexavalent chromium elution, but it is in the range of 500 to 1000 ° C. while contacting with atmospheric gas having an oxygen content of 2.5% or less. There is a problem that it is impossible to treat the soil in-situ because it is necessary to heat-treat it.
従って、本発明の目的は、６価クロム溶出量が多い土壌に関しても原位置で処理することが可能で、かつ、６価クロムの溶出を抑制することができる６価クロムの溶出抑制材を提供することにある。 Accordingly, an object of the present invention is to provide a hexavalent chromium elution suppressing material that can be processed in situ even for soil with a large amount of hexavalent chromium elution, and can suppress the elution of hexavalent chromium. There is to do.
本発明者等は、上記課題を解決するために鋭意研究した結果、酸化マグネシウムと硫酸第一錫を組み合わせることによって、上記課題を解決できることを見出し、本発明を完成した。
すなわち、本発明は、酸化マグネシウム及び硫酸第一錫を含むことを特徴とする６価クロムの溶出抑制材である（請求項１）。
また、本発明においては、上記材料に加えて、さらに炭酸カルシウムを含むことが好ましい（請求項２）。
The present inventors have carried out an extensive study to solve the above problems, by combining magnesium oxide and stannous sulfate, can solve the above problems, and completed the present invention.
That is, the present invention is a dissolution suppressor of hexavalent chromium, which comprises a magnesium oxide and stannous sulfate (claim 1).
Further, in the present invention, it is preferable that calcium carbonate is further contained in addition to the above materials (claim 2).
本発明の６価クロムの溶出抑制材を用いることにより、６価クロム溶出量が多い土壌に関しても原位置で処理でき、また、６価クロムの溶出を抑制することができる。また、本発明の６価クロムの溶出抑制材は、実用上十分な固化強度を発現することができる。 By using the hexavalent chromium elution suppressing material of the present invention, soil with a large amount of hexavalent chromium elution can be treated in situ, and elution of hexavalent chromium can be suppressed. In addition, the hexavalent chromium elution suppressing material of the present invention can exhibit practically sufficient solidification strength.
以下、本発明を詳細に説明する。
本発明で使用する酸化マグネシウムとしては、炭酸マグネシウムを焼成して得たものや水酸化マグネシウムを焼成して得たもの等が挙げられ、なかでも炭酸マグネシウム又は水酸化マグネシウムを主要原料として、好ましくは650〜900℃、より好ましくは750〜900℃、特に好ましくは800〜900℃で焼成して得た酸化マグネシウムを使用することが好ましい。炭酸マグネシウム又は水酸化マグネシウムを主要原料として前記温度で焼成して得た酸化マグネシウムは、土壌に添加・混合した場合に優れた６価クロムの溶出抑制効果を発揮するとともに、実用上十分な固化強度を発現することができる。
なお、酸化マグネシウムの原料である炭酸マグネシウム又は水酸化マグネシウムは、６価クロムの溶出抑制効果の観点からは不純物含有量が少ない原料を使用することが好ましく、焼成後の酸化マグネシウム量が85質量％以上（より好ましくは90質量％以上）となる原料を使用することが好ましい。
Hereinafter, the present invention will be described in detail.
Examples of the magnesium oxide used in the present invention include those obtained by firing magnesium carbonate and those obtained by firing magnesium hydroxide. Among them, magnesium carbonate or magnesium hydroxide is preferably used as a main raw material, It is preferable to use magnesium oxide obtained by firing at 650 to 900 ° C, more preferably 750 to 900 ° C, particularly preferably 800 to 900 ° C. Magnesium oxide obtained by calcining magnesium carbonate or magnesium hydroxide as the main raw material at the above temperature exhibits an excellent hexavalent chromium elution suppression effect when added to and mixed with soil, and has practically sufficient solidification strength. Can be expressed.
In addition, it is preferable to use the raw material with few impurities content from the viewpoint of the elution suppression effect of hexavalent chromium, and the magnesium oxide amount after baking is 85 mass% for the magnesium carbonate or magnesium hydroxide which is the raw material of magnesium oxide. It is preferable to use a raw material that makes the above (more preferably 90% by mass or more).
酸化マグネシウムの平均粒径（粒径加積曲線における通過質量百分率50％の時の粒径）は、10〜30μｍであることが好ましく、10〜20μｍであることがより好ましい。酸化マグネシウムの平均粒径が10μｍより小さいものは入手が困難であるうえ、サイロ等への保管にいたってはシュート詰まり等のトラブルを引き起こしやすくなり、コストも高くなるので好ましくない。一方、酸化マグネシウムの平均粒径が30μｍより大きいと６価クロムの溶出抑制効果が低減するとともに、実用上十分な固化強度を発現することも困難となるので好ましくない。
なお、酸化マグネシウムの密度は、3.0〜3.6g/cm3であることが好ましく、3.3〜3.6g/cm3であることがより好ましい。密度が前記範囲にある酸化マグネシウムは、風化によって受けた劣化が小さいことから水和活性度が高く、６価クロムの溶出抑制効果に優れるうえ、固化強度の発現にも優れる。
The average particle size of magnesium oxide (particle size when the passing mass percentage is 50% in the particle size accumulation curve) is preferably 10 to 30 μm, and more preferably 10 to 20 μm. Magnesium oxide having an average particle size smaller than 10 μm is not preferred because it is difficult to obtain, and storage in a silo tends to cause troubles such as clogging of shoots and increases costs. On the other hand, if the average particle diameter of magnesium oxide is larger than 30 μm, the effect of suppressing the elution of hexavalent chromium will be reduced, and it will also be difficult to achieve practically sufficient solidification strength, which is not preferable.
The density of the magnesium oxide is preferably 3.0~3.6g / cm 3, more preferably 3.3~3.6g / cm 3. Magnesium oxide having a density in the above-mentioned range has high hydration activity due to small deterioration caused by weathering, and is excellent in the effect of inhibiting elution of hexavalent chromium, and is also excellent in expression of solidification strength.
本発明で使用する硫酸第一錫としては、例えば、工業用硫酸第一錫粉末や試薬の硫酸第一錫粉末等を使用することができる。 Stannous sulfate for use in the present invention, for example, can be used for industrial stannous powder or reagent stannous powder etc. sulfate.
本発明において、酸化マグネシウムと硫酸第一錫の配合割合は、酸化マグネシウム100質量部に対して、硫酸第一錫が0.1〜10質量部であることが好ましく、0.5〜８質量部がより好ましく、１〜６質量部が特に好ましい。酸化マグネシウム100質量部に対して、硫酸第一錫が0.1質量部未満では、６価クロム溶出量が多い土壌に対しての６価クロムの溶出抑制効果が低減することがあるので好ましくない。一方、酸化マグネシウム100質量部に対して、硫酸第一錫が10質量部を越えると、コスト高になるうえ、固化強度の発現性も低下することがあるので好ましくない。
なお、本発明において「６価クロム溶出量が多い土壌」とは、土壌からの６価クロムの溶出量が0.2mg/L以上である土壌を意味する。
In the present invention, the mixing ratio of the magnesium oxide and stannous sulfate, with respect to magnesium oxide 100 parts by weight, preferably stannous sulfate is from 0.1 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, 1 to 6 parts by mass is particularly preferable. Unfavorable with respect to magnesium oxide 100 parts by weight, since the first less than stannous 0.1 parts by weight sulfuric acid, may be the effect of suppressing the elution of hexavalent chromium against hexavalent chromium elution amount is large soil is reduced. On the other hand, with respect to magnesium oxide to 100 parts by mass, when stannous sulfate is more than 10 parts by mass, after which increases the cost, since the expression of the solidified strength may be reduced undesirably.
In the present invention, “soil having a large amount of hexavalent chromium elution” means soil having an elution amount of hexavalent chromium from the soil of 0.2 mg / L or more.
本発明の６価クロムの溶出抑制材においては、上記酸化マグネシウムと硫酸第一錫に加えて、炭酸カルシウムを含むことが好ましい。炭酸カルシウムを含むことにより、例えば、６価クロムを含む酸性土壌においては、酸性土壌のｐＨの緩衝作用により、酸化マグネシウムによる溶出抑制効果を高めることが可能である。 The hexavalent chromium elution inhibitor of the present invention preferably contains calcium carbonate in addition to the magnesium oxide and stannous sulfate. By containing calcium carbonate, for example, in acidic soil containing hexavalent chromium, it is possible to enhance the elution suppression effect by magnesium oxide by the buffering action of the pH of the acidic soil.
炭酸カルシウムとしては、例えば、工業用炭酸カルシウム粉末、試薬の炭酸カルシウム粉末や石灰石粉末等を使用することができるが、石灰石粉末を使用するのが安価であり好ましい。石灰石粉末は、天然原料である石灰石を粉砕して（必要に応じて、乾燥・分級を行って）製造されるものである。また、その他の炭酸カルシウムとして、炭酸カルシウムを主成分とする貝殻、サンゴ等の粉砕物又はその加工物を使用することもできる。 As calcium carbonate, for example, industrial calcium carbonate powder, reagent calcium carbonate powder, limestone powder, and the like can be used, but it is inexpensive and preferable to use limestone powder. Limestone powder is produced by pulverizing limestone, which is a natural raw material (by performing drying and classification as necessary). In addition, as other calcium carbonates, crushed materials such as shells and corals mainly composed of calcium carbonate, or processed products thereof can be used.
炭酸カルシウムのブレーン比表面積は、2000〜10000cm2/gであることが好ましく、3000〜9000cm2/gであることがより好ましく、3500〜8000cm2/gであることが特に好ましい。ブレーン比表面積が2000cm2/g未満では、炭酸カルシウムの反応性が小さく、上記効果が得られない。一方、ブレーン比表面積が10000cm2/gを超えるものは入手が困難であるので好ましくない。 Blaine specific surface area of calcium carbonate is preferably 2000~10000cm 2 / g, more preferably 3000~9000cm 2 / g, particularly preferably 3500~8000cm 2 / g. When the Blaine specific surface area is less than 2000 cm 2 / g, the reactivity of calcium carbonate is small, and the above effect cannot be obtained. On the other hand, those having a Blaine specific surface area exceeding 10000 cm 2 / g are not preferred because they are difficult to obtain.
炭酸カルシウムの配合割合は、酸化マグネシウムと硫酸第一錫の合計量100質量部に対して、50質量部以下であることが好ましく、0.5〜45質量部がより好ましく、１〜40質量部が特に好ましい。炭酸カルシウムの配合割合が、酸化マグネシウムと硫酸第一錫の合計量100質量部に対して、50質量部を越えると、６価クロム溶出量が多い土壌等に対しての６価クロムの溶出抑制効果が低減するとともに強度発現性が低下することがあるので好ましくない。
The blending ratio of calcium carbonate is preferably 50 parts by mass or less, more preferably 0.5 to 45 parts by mass, particularly 1 to 40 parts by mass with respect to 100 parts by mass of the total amount of magnesium oxide and stannous sulfate . preferable. When the blending ratio of calcium carbonate exceeds 50 parts by mass with respect to 100 parts by mass of the total amount of magnesium oxide and stannous sulfate, the elution of hexavalent chromium to the soil with a large amount of hexavalent chromium elution is suppressed. This is not preferable because the effect is reduced and the strength development property may be lowered.
本発明の６価クロムの溶出抑制材の土壌への添加方法は、粉体又はスラリーいずれの添加でもよく、簡便性を重視した場合は粉体で添加し、粉塵の発生抑制や土壌との混合性を考慮した場合はスラリーにした態様で添加する等、適宜選択できる。粉体で添加する場合は、各材料を予め混合しておいても良いし、別々に添加しても良い。スラリーで添加する場合は、スラリーの水粉体比は100〜400質量％であることが好ましい。
溶出抑制材と土壌との混合方法は土壌の改良深さによって異なり、改良深さが２〜３ｍ程度まではスタビライザや特殊バックホウ等の混合機械を用いた原位置混合方式又はプラントで連続的に混合する事前混合方式が採用できる。一方、改良深さが３ｍ以上の場合には機械攪拌翼方式若しくは噴射攪拌方式を用いる深層混合処理工法又は柱列式若しくは等厚壁式を用いるソイルセメント地中連続壁工法がよい。
The addition method of the hexavalent chromium elution inhibitor of the present invention to the soil may be either powder or slurry. If importance is placed on simplicity, it is added as a powder to suppress the generation of dust or mix with the soil. In consideration of the properties, it can be selected as appropriate, for example, in the form of a slurry. When adding by powder, each material may be mixed previously and may be added separately. When added as a slurry, the water-powder ratio of the slurry is preferably 100 to 400% by mass.
The mixing method of the elution control material and the soil varies depending on the soil improvement depth, and until the improvement depth is about 2 to 3 m, it is continuously mixed in the in-situ mixing system or plant using a mixing machine such as a stabilizer or special backhoe. The pre-mixing method can be adopted. On the other hand, when the improved depth is 3 m or more, a deep layer mixed processing method using a mechanical stirring blade method or a jet stirring method, or a soil cement underground continuous wall method using a column array method or an equal thickness wall method is preferable.
本発明の６価クロムの溶出抑制材は、６価クロムに汚染された土壌に対して好適に用いられるものであるが、土壌以外の対象物（例えば、６価クロムを含有する焼却灰、飛灰等）に使用することは差し支えない。 The hexavalent chromium elution suppressing material of the present invention is preferably used for soil contaminated with hexavalent chromium, but it is an object other than soil (for example, incinerated ash containing hexavalent chromium, flying Ash etc.) can be used.
本発明の６価クロムの溶出抑制材を土壌以外の対象物に対して使用する場合、該対象物への添加方法は、粉体又はスラリーいずれの添加でもよく、混合容易性を重視した場合は粉体で添加し、粉塵の発生抑制や対象物との混合性を考慮した場合はスラリーにした態様で添加する等、適宜選択できる。粉体で添加する場合は、各材料を予め混合しておいても良いし、別々に添加しても良い。スラリーで添加する場合は、スラリーの水粉体比は100〜400質量％であることが好ましい。
溶出抑制材と対象物との混合方法は、浅層改良に用いる混合機械（例えば、スタビライザや特殊バックホウ等）を用いて混合する方法や、プラントで連続的に混合する事前混合方式が採用できる。
When the hexavalent chromium elution inhibitor of the present invention is used for an object other than soil, the addition method to the object may be either addition of powder or slurry, and when emphasis is placed on ease of mixing. When added in powder form and considering the dust generation suppression and mixing with the object, it can be selected as appropriate, for example, in the form of a slurry. When adding by powder, each material may be mixed previously and may be added separately. When added as a slurry, the water-powder ratio of the slurry is preferably 100 to 400% by mass.
As a method for mixing the elution inhibitor and the object, a method of mixing using a mixing machine (for example, a stabilizer or a special backhoe) used for shallow layer improvement, or a pre-mixing method of continuously mixing in a plant can be adopted.
以下、実施例により本発明を具体的に説明するが、本発明は下記の実施例に何ら限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following Example at all.
１．模擬汚染土壌からの６価クロム溶出低減効果の確認
（１）６価クロムの溶出抑制材の調製
以下の材料を表１に示す配合割合で混合して、６価クロムの溶出抑制材を調製した。
1)酸化マグネシウム:炭酸マグネシウムを850℃で焼成後、平均粒径13μｍに粉砕したもの
2)硫酸錫：硫酸第一錫(関東化学製試薬特級)
3)炭酸カルシウム：奥多摩工業製炭酸カルシウム(ブレーン比表面積5000cm2/g)
1. Confirmation of Hexavalent Chromium Elution Reduction Effect from Simulated Contaminated Soil (1) Preparation of Hexavalent Chromium Elution Control Material The following materials were mixed at the blending ratio shown in Table 1 to prepare a hexavalent chromium elution suppression material. .
1) Magnesium oxide: Magnesium carbonate calcined at 850 ° C and then ground to an average particle size of 13μm
2) Tin sulfate: Stannous sulfate (special grade reagent manufactured by Kanto Chemical)
3) Calcium carbonate: Calcium carbonate manufactured by Okutama Kogyo (Brain specific surface area 5000cm 2 / g)
（２）模擬汚染土壌の調製
粘性土(含水比118％)にニクロム酸カリウム(試薬特級)を添加・混合後、24時間静置して、６価クロム含有量250mg/kg、６価クロム溶出量25mg/Lの模擬汚染土壌を調製した。
(2) Preparation of simulated contaminated soil Potassium dichromate (special grade reagent) was added to and mixed with clay soil (water content: 118%) and allowed to stand for 24 hours, with hexavalent chromium content of 250 mg / kg and hexavalent chromium elution. A simulated contaminated soil with an amount of 25 mg / L was prepared.
（３）評価
上記模擬汚染土壌に、表１の各溶出抑制材を表２に示す量となるように添加し、ホバートミキサで３分間混合して、JGS 0821「安定処理土の締固めをしない供試体作製」に準じて直径3.5cm×高さ7cmの供試体を作製した。作製した供試体は20℃にて湿空養生を行い、材齢７日および28日において一軸圧縮試験を実施した。また、圧縮試験後の供試体を使用して、６価クロムの溶出量を環境庁告示46号法に準じて、ジフェニルカルバジド吸光光度法で測定した。
その結果を表２に示す。
(3) Evaluation Add to the simulated contaminated soil each elution inhibitor shown in Table 1 to the amount shown in Table 2 and mix for 3 minutes with a Hobart mixer. JGS 0821 “Do not compact stabilized soil. A specimen having a diameter of 3.5 cm and a height of 7 cm was prepared according to “Preparation of Specimen”. The prepared specimens were subjected to moisture curing at 20 ° C., and uniaxial compression tests were carried out at the age of 7 and 28 days. Moreover, the elution amount of hexavalent chromium was measured by the diphenylcarbazide absorptiometric method according to the Environmental Agency Notification No.46 method using the specimen after the compression test.
The results are shown in Table 2.
表２から、本発明の６価クロムの溶出抑制材は、模擬汚染土壌からの６価クロムの溶出量を大幅に低減できることが分かる。また、本発明の６価クロムの溶出抑制材は、実用上十分な固化強度を発現できることも分かる。 From Table 2, it can be seen that the hexavalent chromium elution inhibitor of the present invention can greatly reduce the elution amount of hexavalent chromium from the simulated contaminated soil. It can also be seen that the hexavalent chromium elution inhibitor of the present invention can exhibit practically sufficient solidification strength.
２．６価クロム汚染土壌からの６価クロム溶出低減効果の確認
（１）６価クロムの溶出抑制材の調製
上記の材料を表３に示す配合割合で混合して、６価クロムの溶出抑制材を調製した。
2. Confirmation of hexavalent chromium elution reduction effect from hexavalent chromium contaminated soil (1) Preparation of hexavalent chromium elution suppression material Mixing the above materials in the blending ratio shown in Table 3 to suppress elution of hexavalent chromium A material was prepared.
（２）評価
６価クロム汚染土壌（６価クロム含有量7.5mg/kg、６価クロム溶出量0.98mg/L、含水比142％）に、表３の各溶出抑制材を表４に示す量となるように添加して、実施例１と同様にして一軸圧縮試験及び６価クロムの溶出量を測定した。
その結果を表４に示す。
(2) Evaluation The amount of each elution inhibitor shown in Table 3 in hexavalent chromium-contaminated soil (hexavalent chromium content 7.5 mg / kg, hexavalent chromium elution amount 0.98 mg / L, water content 142%) In the same manner as in Example 1, the uniaxial compression test and the elution amount of hexavalent chromium were measured.
The results are shown in Table 4.
表４から、本発明の６価クロムの溶出抑制材は、６価クロム溶出量が多い土壌からの６価クロムの溶出量を大幅に低減できることが分かる。また、実用上十分な固化強度を発現できることも分かる。 From Table 4, it can be seen that the hexavalent chromium elution suppressing material of the present invention can greatly reduce the elution amount of hexavalent chromium from soil having a large amount of hexavalent chromium elution. Moreover, it turns out that practically sufficient solidification strength can be expressed.
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| JP2003117538A (en) * | 2001-10-15 | 2003-04-22 | Nippon Kankyo System:Kk | Treating method and treating equipment for soil, or the like, contaminated with hexavalent chromium |
| JP2003225640A (en) * | 2001-11-30 | 2003-08-12 | Matsuda Giken Kogyo Kk | Solidifying and insolubilizing agent for contaminated soil |
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| JPH03205331A (en) * | 1989-06-13 | 1991-09-06 | Hitoshi Hatano | Cement admixture |
| JP2001527465A (en) * | 1997-05-29 | 2001-12-25 | ペリクラセ プロプライエタリー リミテッド | How to encapsulate hazardous waste |
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