JP3617405B2 - Water bottom structure and bottom / water purification method - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、広くは水域整備技術に属し、特に岩礁域の生物の棲息環境に適する水底構造および底泥が堆積した水底の底質・水質の浄化法に関する。
【０００２】
【従来の技術】
底質・水質の浄化技術としては、従来から底泥に覆砂したり、底泥を浚渫したりする方法などが知られている。
【０００３】
ここで用いられる覆砂材としては、海砂や山砂など化学反応をともなわずに底泥を覆う効果のみを有する材料や、石灰のように底泥中の燐の一部を化学反応により除去できる材料が用いられている。海砂や山砂の場合には、覆砂後の海底を砂質域に棲息する貝類や魚類などの棲息場造成も同時になされている事もある。また、築磯効果を期待して天然石を用いる場合もある。
【０００４】
しかし、化学反応による底質・水質の浄化作用を有しない海砂や山砂などの天然砂を覆砂材として用いる場合は、例えば、夏期の海水停滞期や生物の活動が活発な時期には、ヘドロが堆積していない状態でも間隙水中で硫酸還元菌の作用により数ｐｐｍのＨ２Ｓが生成してしまうという問題がある。また、石灰を用いる場合は、費用が高価となることや、水質が高アルカリになる場合があること、石灰が水底で板状になってしまう等の問題がある。天然石を単独で用いる場合は、天然石への海藻の付着繁殖は行われるものの、底泥からの栄養塩類の溶出を防止する効果はほとんどなく、ヘドロの堆積が問題となっている水域へ適用しても底質・水質の改善効果は十分なものではない。さらに、天然石や山砂は山を切り崩して採取する必要があり、近年の環境問題から、その確保が難しくなりつつある。
【０００５】
上記のような問題に対し、特開平３−４９８８号公報には粒状の製鋼スラグを覆砂材として用いる技術が開示されている。具体的には、粒状の製鋼スラグとして粒径が１ｍｍ程度の転炉スラグを用いることにより、その覆砂効果と転炉スラグ中のＣａＯやＦｅ２Ｏ３成分によるＨ２ＳやＰＯ４ ３−の化学的除去効果により底質・水質の浄化が図られることが報告されている。
【０００６】
【発明が解決しようとする課題】
しかしながら、底質・水質の浄化が必要な水域は汚染された浮泥の流入が多いために、特開平３−４９８８号公報に記載されている粒径が１ｍｍ程度の転炉スラグを用いると、覆砂初期には底質・水質の浄化効果を有するが、次第に転炉スラグが固結するため、生物相の回復が遅く生物による底泥の分解効果が期待できない。さらに、粒径が１ｍｍ程度と細かいため、岩礁域に棲息する生物にとって適するものとはいえず、別に岩礁域を造成する必要がある。
【０００７】
このような問題に対しては、粒径の大きい製鋼スラグを直接底泥の上に敷設する方法も考えられるが、この場合、製鋼スラグが底泥の中に沈み込んでしまい、特にヘドロが５０ｃｍ以上堆積しているような水底では、敷設した製鋼スラグを有効に底質・水質浄化材として作用させるためには、製鋼スラグを底泥の厚さ以上に敷設しなければならず、スラグの敷設量が非常に多くなってしまう。
【０００８】
また、高炉水砕スラグを覆砂材として用いる技術が特開平４−２１５９００号公報に開示されている。しかし、高炉水砕スラグだけでは、水底の底泥からのＳの発生量が多い場合、Ｓの吸着効果が短期間で無くなってしまうという問題がある。さらに、高炉水砕スラグは潜在水硬性を有するため、特に底泥と直接接する場合は、高炉水砕スラグが固結してしまい、岩礁域の生物にとって適当な棲息場でない。
【０００９】
本発明はこのような問題を解決するためになされたもので、長期的な底質・水質浄化の効果を有し、Ｈ２Ｓの発生を抑制し、かつ岩礁域の生物の棲息環境に適する水底構造および底泥が堆積した水底の底質・水質の浄化法を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記の課題は次の発明により解決される。第１の発明は、内部摩擦角が３５°以上の粉粒物からなる下部層と、その上に製鋼スラグを含有する上部層とを有する水底構造である。第２の発明は、高炉水砕スラグからなる下部層と、その上に製鋼スラグを含有する上部層とを有する水底構造である。
【００１１】
第３の発明は、内部摩擦角が２５°以上の粉粒物からなる下部層と、その上に製鋼スラグを含有する上部層とを有し、前記下部層の平均厚さが１０ｃｍ以上であり、前記上部層の平均厚さが５ｃｍ以上であることを特徴とする水底構造である。第４の発明は、第１の発明乃至第３の発明のいずれかにおいて製鋼スラグが、粒径１０ｍｍ以上のものを８５質量％以上含んでいるものであることを特徴とする請求項１乃至３のいずれかに記載の水底構造である。
【００１２】
第５の発明は、内部摩擦角が３５°以上の粉粒物からなる下部層を形成し、その上に製鋼スラグを含有する上部層を形成することを特徴とする底質・水質浄化法である。第６の発明は、高炉水砕スラグからなる下部層を形成し、その上に製鋼スラグを含有する上部層を形成することを特徴とする底質・水質浄化法である。
【００１３】
第７の発明は、内部摩擦角が２５°以上の粉粒物からなる下部層を形成し、その上に製鋼スラグを含有する上部層を形成する底質・水質浄化法であって、前記下部層の平均厚さを１０ｃｍ以上とし、前記上部層の平均厚さを５ｃｍ以上とすることを特徴とする底質・水質浄化法である。第８の発明は、第５の発明乃至第７の発明のいずれかにおいて、製鋼スラグに、粒径１０ｍｍ以上のものを８５質量％以上含んでいるものを使用することを特徴とする請求項５乃至７のいずれかに記載の底質・水質浄化法である。
【００１４】
【発明の実施の形態】
以下、本発明に係る実施形態の一例について説明する。なお、以下の説明において「％」は質量百分率を示すものとする。
【００１５】
本発明に係る水底構造は、底泥上に形成される内部摩擦角が高い粉粒物からなる下部層と、製鋼スラグを含有する上部層との２層からなるものである。
【００１６】
ここで、前記内部摩擦角が高い粉粒物としては、内部摩擦角が２５°以上の粉粒物であり、好ましくは３０°以上、さらに好ましくは３５°以上のものである。このような粉粒物として、砂（内部摩擦角約３０°）あるいは高炉水砕スラグ（内部摩擦角約３５°〜４０°）などの１種又は２種以上を用いることができる。
【００１７】
高炉水砕スラグは、製鋼スラグと同様に底泥からのＨ２Ｓ発生を抑制する効果を有し、さらに嵩比重が１．１〜１．３程度と軽くしかも角張った粒子形状のため、高炉水砕スラグ同士のかみ合わせが良く、このため底泥の中に沈み込まず、かつ上部に重量物が積載されても内部摩擦角が低い粉粒物のように流動せずに重量物をささえる性質を有する。従って、下部層を高炉水砕スラグで形成することにより下部層及び上部層ともに底泥の中に沈み込まず、上部層の特性を最大限に引き出すことが可能となるため好ましい。
【００１８】
ここで、前記製鋼スラグを含有する上部層としては、製鋼スラグを５０％以上、好ましくは８０％以上含有しているものが好ましい。なお、製鋼スラグとしては、転炉、電気炉、混銑車などで発生したスラグのみならず、脱珪スラグ、脱硫スラグ、脱燐スラグなどの溶銑予備処理スラグなどを用いることもできる。
【００１９】
また、前記製鋼スラグは、粒径１０ｍｍ以上のものを８５％以上含んでいるものが好ましく、粒径２０ｍｍ以上のものを９０％以上含んでいるものがさらに好ましい。ここで、製鋼スラグの粒度調整方法としては、溶融スラグを冷却固化後、重機等またはクラッシングプラントなどにより破砕し、例えば１０ｍｍ以上のふるい目のふるいを用いて選別する方法、水洗又は風力分級による方法などを用いることができる。
【００２０】
上部層の主たる材料である製鋼スラグが粒径１０ｍｍ以上のものを８５％以上含むことにより、製鋼スラグ間の固結が防止されるので、上部層での間隙が大きく空き、浮泥がその間隙に沈降することにより製鋼スラグの表面がヘドロで覆われることがなくなり、その結果底質・水質の浄化効果が長期間維持される。また、上部層における間隙は、付着性の珪藻やごかい、えびなどの岩礁域の生物の好適な住処となり、生物相が早期に付着回復し、付着生物による底泥の分解も行われ、この点からも底質・水質の浄化効果が長期間維持される。さらに、前記製鋼スラグが粒径２０ｍｍ以上のものを９０％以上含むことにより、上部層での間隙がより大きくなり、底質・水質の浄化効果の持続性が向上し、かつハゼ、アナゴ、ウナギなどの魚類の住処としても有効となる。
【００２１】
なお、製鋼スラグにはＣａＯが含有されているため、長期にわたり水と接すると、ＣａＯ＋Ｈ２Ｏ→Ｃａ（ＯＨ）２の反応により製鋼スラグが崩壊し、小さな粒が生成し、この生成した小さな粒が製鋼スラグの間隙に入り込んで底質・水質の浄化効果を低減させるという懸念もあるが、上部層の主たる材料である製鋼スラグが粒径１０ｍｍ以上を８５％以上含むことにより、粒径が１ｍｍ程度の製鋼スラグを用いた場合と比較して長期的な底質・水質の浄化効果を有する。なお、製鋼スラグの崩壊を防ぐ方法として、大気、蒸気、オートクレーブ、炭酸ガスなどでエージング処理した製鋼スラグを用いることも有効である。
【００２２】
ここで、前記製鋼スラグを含有する上部層における製鋼スラグ以外の部分は、天然石、コンクリート材、コンクリート廃材、陶板、鉄骨、鉄筋などを用いることができる。
【００２３】
さらに、本発明に係る水底構造は、内部摩擦角が高い粉粒物からなる下部層の平均厚さが１０ｃｍ以上であり、製鋼スラグを含有する上部層の平均厚さが５ｃｍ以上であることが好ましい。なお、下部層及び上部層の厚さの上限については特に限定されないが、工業性あるいは形成性などを考慮して決定することが好ましく、下部層の平均厚さとしては２ｍ以下、上部層の平均厚さとしては５ｍ以下が好ましい。特に、下部層の平均厚みを２ｍより厚くしても、下部層が上部層を支持する効果が変わらないばかりか、費用が掛かってしまい工業的でない。
【００２４】
前記内部摩擦角が高い粉粒物からなる下部層の平均厚さを１０ｃｍ以上とすることにより、粉粒物同士のかみ合わせが安定し、上部層を支えるための効果がより向上する。また、前記製鋼スラグを含有する上部層平均厚さを５ｃｍ以上とすることにより、上部層での間隙が十分に確保され、より安定して長期的な底質・水質の浄化効果が得られる。なお、ここで、下部層及び上部層の厚さを平均厚さで規定しているが、これは敷設方法により形成層の厚さに多少のバラツキが起こる場合があるためである。
【００２５】
本発明に係る水底構造を用いた底質・水質浄化法は、内部摩擦角が高い粉粒物からなる下部層を形成した後、その上に製鋼スラグを含有する上部層を形成するものである。
【００２６】
さらに、内部摩擦角が高い粉粒物からなる下部層の平均厚さを１０ｃｍ以上とし、製鋼スラグを含有する上部層の平均厚さを５ｃｍ以上とすることが好ましい。
【００２７】
内部摩擦角が高い粉粒物からなる下部層は、粉粒物同士のかみ合わせが良く、このため底泥の中に沈み込まず、かつ上部に重量物が積載されても内部摩擦角が低い粉粒物のように流動せずに重量物をささえる性質を有する。従って、下部層を内部摩擦角が高い粉粒物で形成することにより下部層及び上部層ともに底泥の中に沈み込まず、上部層の特性を最大限に引き出すことが可能となる。さらに、製鋼スラグを含有する上部層が底泥と直接接触しないため、製鋼スラグと底泥との反応による固結が軽減され、製鋼スラグの間隙が岩礁域の生物の好適な住処となる。
【００２８】
なお、内部摩擦角の大きい粉粒物からなる下部層と製鋼スラグを含有する上部層の水底への敷設は、ガット船等を用いた方法で行うことができる。
【００２９】
また、水底の岩などにより水底構造が局所的に凸部となっているような場所では、下部層又は下部層と上部層の厚さが局所的にゼロとなることもあり得るが本発明の効果が損なわれることはない。
【００３０】
【実施例】
（実施例１）
浮泥の流入が多い海底の底泥上に、平均厚さ２ｃｍ〜５０ｃｍの範囲で高炉水砕スラグからなる下部層を形成し、さらにその上に粒径２０ｍｍ以上を９５％含む転炉スラグからなる上部層を平均厚さ２０ｃｍ及び５０ｃｍで形成し、底泥への上部層の沈み込みを調査した。その結果をそれぞれの層の平均厚さとともに表１に示す。
【００３１】
【表１】
表１に示されるように、転炉スラグの厚さが２０ｃｍの場合、高炉水砕スラグの厚さが５ｃｍ以上で転炉スラグの底泥への沈み込みが防止できた。また、転炉スラグの厚さが５０ｃｍの場合は、高炉水砕スラグの厚さが１０ｃｍ以上で転炉スラグの底泥への沈み込みが防止できた。
【００３３】
（実施例２）
浮泥の流入が多い海底の底泥上に、高炉水砕スラグからなる下部層を２０ｃｍの厚さで形成し、さらにその上に表２に示す種々の粒度に調整した転炉スラグからなる上部層を１０ｃｍの厚さで形成した。目視による上部層での間隙と珪藻類の着生の有無を経時的に観察した結果を表２に示す。
【００３４】
【表２】
いずれの条件においても転炉スラグの底泥への沈み込みは見られず高炉水砕スラグを下部層として形成した効果が認められた。上部層の転炉スラグの粒径を１０ｍｍ以上８５％以上とした条件では、形成３年経過後でも上部層に間隙が観察され、長期的な底質・水質の浄化効果が確認された。また、転炉スラグの表面に珪藻の着生も確認され、生物相が早期に付着回復していることが確認された。
【００３６】
（実施例３）
浮泥の流入が多い海底の底泥上に、高炉水砕スラグからなる下部層を３０ｃｍの厚さで形成し、さらにその上に表３に示す種々の粒度に調整した転炉スラグからなる上部層を１５ｃｍの厚さで形成した。目視による上部層での間隙と珪藻類の着生の有無を経時的に観察した結果を表３に示す。
【００３７】
【表３】
いずれの条件においても転炉スラグの底泥への沈み込みは見られず高炉水砕スラグを下部層として形成した効果が認められた。上部層の転炉スラグの粒径を２０ｍｍ以上９０％以上（１０ｍｍ以上９５％以上）とした条件では、形成５年経過後でも上部層に間隙が観察され、長期的な底質・水質の浄化効果が確認された。また、転炉スラグの表面に珪藻の着生も確認され、生物相が早期に付着回復していることが確認された。さらに、上部層での間隙にハゼなどの魚類が棲息していることも観察された。
【００３９】
（実施例４）
浮泥の流入が多い海底の底泥上に、高炉水砕スラグからなる下部層を１０ｃｍの厚さで形成し、さらにその上に表４に示す種々の粒度に調整した転炉スラグからなる上部層を５ｃｍの厚さで形成した。また、それぞれの粒度毎に蒸気によりエージングを行ったものと行わなかったものについて比較した。目視による上部層での間隙と珪藻類の着生の有無を経時的に観察した結果を表４に示す。
【００４０】
【表４】
いずれの条件においても転炉スラグの底泥への沈み込みは見られず高炉水砕スラグを下部層として形成した効果が認められた。上部層の転炉スラグをエージング処理したものを用い、その粒径を２０ｍｍ以上７５％以上（１０ｍｍ以上８５％以上）とした条件では、形成３年経過後でも上部層に間隙が観察され、長期的な底質・水質の浄化効果が確認された。また、転炉スラグの表面に珪藻の着生も確認され、生物相が早期に付着回復していることが確認された。
【００４２】
また、上部層の転炉スラグの粒径を大きくすることによって、上部層に間隙が観察されなくなるまでの期間は長期化し、しかもエージング処理した転炉スラグの方が上部層での間隙が長期に渡って観察された。
【００４３】
【発明の効果】
以上説明したように本発明によれば、長期的な底質・水質浄化の効果を有し、Ｈ２Ｓの発生を抑制し、かつ岩礁域の生物の棲息環境に適する水底構造および底泥が堆積した水底の底質・水質の浄化法が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention generally relates to water area maintenance technology, and particularly relates to a bottom structure suitable for the habitat environment of organisms in reef areas, and a method for purifying bottom sediment / water quality of bottom sediment where sediment has accumulated.
[0002]
[Prior art]
Conventionally known methods for purifying the bottom and water quality include a method of covering the bottom mud with sand and dripping the bottom mud.
[0003]
The sand-capping material used here is a material that only covers the bottom mud without chemical reaction, such as sea sand and mountain sand, and some of the phosphorus in the bottom mud is removed by chemical reaction, such as lime. Materials that can be used are used. In the case of sea sand and mountain sand, a habitat for shellfish and fish that inhabit the sandy area of the seabed after covering is sometimes created. In some cases, natural stone is used in anticipation of the construction effect.
[0004]
However, when using natural sand such as sea sand or mountain sand that does not have a bottom-and-water purification effect by chemical reaction as a sand-capping material, for example, in the summer seawater stagnation period or when biological activities are active Even when sludge is not deposited, there is a problem that several ppm of H 2 S is generated by the action of sulfate-reducing bacteria in the pore water. Moreover, when using lime, there exist problems, such as expense becoming expensive, a water quality becoming high alkali, and lime becoming plate shape with a water bottom. When natural stone is used alone, seaweed adheres to and propagates on natural stone, but it has little effect on preventing the elution of nutrients from the bottom mud. However, the effect of improving the bottom and water quality is not sufficient. Furthermore, natural stones and mountain sands need to be cut and collected, and due to environmental problems in recent years, it is becoming difficult to secure them.
[0005]
To solve the above problems, Japanese Patent Laid-Open No. 3-4988 discloses a technique using granular steelmaking slag as a sand covering material. Specifically, by using a converter slag having a particle size of about 1 mm as the granular steelmaking slag, its sand-capping effect and H 2 S or PO 4 3− due to CaO or Fe 2 O 3 component in the converter slag. It has been reported that purification of sediment and water can be achieved by the chemical removal effect of.
[0006]
[Problems to be solved by the invention]
However, since the water area that requires purification of the bottom sediment and water quality has a large inflow of contaminated floating mud, using a converter slag having a particle size of about 1 mm described in JP-A-3-4988, Although it has an effect of purifying sediment and water in the early stage of sand-capping, since the converter slag gradually solidifies, the recovery of the biota is slow and the bottom mud decomposition effect by organisms cannot be expected. Furthermore, since the particle size is as small as about 1 mm, it cannot be said that it is suitable for organisms living in the reef area, and it is necessary to create a separate reef area.
[0007]
For such a problem, a method of laying a steelmaking slag having a large particle size directly on the bottom mud is also conceivable. However, in this case, the steelmaking slag sinks into the bottom mud, and the sludge is particularly 50 cm. In order to allow the steelmaking slag that has been deposited to act effectively as a bottom and water purification material, the steelmaking slag must be laid more than the thickness of the bottom mud. The amount becomes very large.
[0008]
Further, a technique using blast furnace granulated slag as a sand covering material is disclosed in Japanese Patent Laid-Open No. 4-215900. However, the blast furnace granulated slag alone has a problem that the adsorption effect of S is lost in a short period of time when the amount of S generated from the bottom mud is large. Furthermore, since granulated blast furnace slag has latent hydraulic properties, especially when it comes into direct contact with the bottom mud, the granulated blast furnace slag is consolidated, and is not a suitable habitat for living organisms in reef areas.
[0009]
The present invention has been made to solve such a problem, has a long-term effect of purifying sediment / water quality, suppresses the generation of H 2 S, and is suitable for the habitat environment of organisms in rocky areas. The purpose is to provide a method for purifying the bottom and water quality of the bottom where the bottom structure and bottom mud are accumulated.
[0010]
[Means for Solving the Problems]
The above problems are solved by the following invention. 1st invention is a bottom structure which has the lower layer which consists of a granular material whose internal friction angle is 35 degrees or more, and the upper layer which contains steelmaking slag on it. 2nd invention is a water bottom structure which has the lower layer which consists of granulated blast furnace slag, and the upper layer which contains steelmaking slag on it.
[0011]
In the third invention includes a lower layer which is internal friction angle consisting granular material above 25 °, and an upper layer containing steelmaking slag thereon, the average thickness of the lower layer is more than 10cm There, the average thickness of the upper layer is a water bottom structure, characterized in that at 5cm or more. A fourth invention is characterized in that the steelmaking slag according to any one of the first to third inventions contains 85 mass% or more of a steel having a particle diameter of 10 mm or more. The water bottom structure according to any one of the above.
[0012]
The fifth invention is a bottom / water purification method characterized in that a lower layer made of a granular material having an internal friction angle of 35 ° or more is formed, and an upper layer containing steelmaking slag is formed thereon. is there. A sixth invention is a bottom / water purification method characterized by forming a lower layer made of granulated blast furnace slag and forming an upper layer containing steelmaking slag thereon.
[0013]
The seventh invention is a bottom / water purification method in which a lower layer made of a granular material having an internal friction angle of 25 ° or more is formed, and an upper layer containing steelmaking slag is formed on the lower layer. An average thickness of the layer is 10 cm or more, and an average thickness of the upper layer is 5 cm or more. The eighth invention is characterized in that, in any one of the fifth to seventh inventions, the steelmaking slag contains 85% by mass or more of a particle size of 10 mm or more. The bottom sediment / water purification method according to any one of 1 to 7.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment according to the present invention will be described. In the following description, “%” indicates a mass percentage.
[0015]
The water bottom structure according to the present invention consists of two layers, a lower layer made of a granular material having a high internal friction angle formed on the bottom mud and an upper layer containing steelmaking slag.
[0016]
In this case, the granular material having a high internal friction angle is a granular material having an internal friction angle of 25 ° or more, preferably 30 ° or more, and more preferably 35 ° or more. As such a granular material, 1 type (s) or 2 or more types, such as sand (internal friction angle about 30 degrees) or blast furnace granulated slag (internal friction angle about 35 degrees-40 degrees), can be used.
[0017]
The blast furnace granulated slag has the effect of suppressing the generation of H 2 S from the bottom mud as in the case of steelmaking slag, and further has a bulk specific gravity of about 1.1 to 1.3 and a square particle shape. Granulated slag is well meshed, so it doesn't sink into the bottom mud, and even when a heavy object is loaded on top, it can hold a heavy object without flowing like a granular material with a low internal friction angle Have Therefore, it is preferable to form the lower layer with granulated blast furnace slag because neither the lower layer nor the upper layer sinks into the bottom mud, and the characteristics of the upper layer can be maximized.
[0018]
Here, the upper layer containing the steelmaking slag preferably contains 50% or more, preferably 80% or more of the steelmaking slag. As steelmaking slag, not only slag generated in converters, electric furnaces, kneading vehicles, etc., but also hot metal pretreatment slag such as desiliconized slag, desulfurized slag, and dephosphorized slag can be used.
[0019]
The steelmaking slag preferably contains 85% or more of particles having a particle size of 10 mm or more, and more preferably contains 90% or more of particles having a particle size of 20 mm or more. Here, as a method of adjusting the particle size of the steelmaking slag, after the molten slag is cooled and solidified, the molten slag is crushed by a heavy machine or a crushing plant, and sorted using a sieve having a sieve size of 10 mm or more, by water washing or air classification A method or the like can be used.
[0020]
Since the steelmaking slag, which is the main material of the upper layer, contains 85% or more of particles having a particle size of 10 mm or more, solidification between the steelmaking slags is prevented. As a result, the surface of the steelmaking slag is not covered with sludge, and as a result, the effect of purifying the bottom and water is maintained for a long time. In addition, the gap in the upper layer becomes a suitable place for living organisms in the reef area such as adherent diatoms, sea bream, shrimp, etc., the biota attaches and recovers early, and the bottom mud is decomposed by the attached organisms. Therefore, the purification effect of the bottom and water quality is maintained for a long time. Furthermore, by containing 90% or more of the steelmaking slag having a particle size of 20 mm or more, the gap in the upper layer becomes larger, the sustainability of the purification effect of the bottom sediment and water quality is improved, and goby, anago, eel It is also effective as a place to live fish.
[0021]
Since steelmaking slag contains CaO, when it comes into contact with water for a long period of time, the steelmaking slag collapses due to the reaction of CaO + H 2 O → Ca (OH) 2 , producing small grains, and these produced small grains However, the steelmaking slag, which is the main material of the upper layer, contains 85% or more of a particle size of 10 mm or more, so that the particle size is 1 mm. Compared to the case of using steelmaking slag of a certain degree, it has a long-term purification effect of bottom and water quality. As a method for preventing the collapse of steelmaking slag, it is also effective to use steelmaking slag that has been aged with air, steam, autoclave, carbon dioxide, or the like.
[0022]
Here, natural stone, a concrete material, a concrete waste material, a ceramic plate, a steel frame, a reinforcing bar, etc. can be used for parts other than the steelmaking slag in the upper layer containing the steelmaking slag.
[0023]
Further, in the water bottom structure according to the present invention, the average thickness of the lower layer made of a granular material having a high internal friction angle is 10 cm or more, and the average thickness of the upper layer containing the steelmaking slag is 5 cm or more. preferable. In addition, although it does not specifically limit about the upper limit of the thickness of a lower layer and an upper layer, It is preferable to determine in consideration of industrial property or formability, etc., as average thickness of a lower layer, 2 m or less, the average of an upper layer The thickness is preferably 5 m or less. In particular, even if the average thickness of the lower layer is greater than 2 m, the effect of the lower layer supporting the upper layer is not changed, and costs are increased, which is not industrial.
[0024]
By setting the average thickness of the lower layer made of the granular material having a high internal friction angle to 10 cm or more, the meshing between the granular materials is stabilized, and the effect for supporting the upper layer is further improved. Further, by setting the average thickness of the upper layer containing the steelmaking slag to 5 cm or more, a sufficient gap in the upper layer is ensured, and a more stable and long-term purification effect of bottom sediment / water quality can be obtained. Here, the thicknesses of the lower layer and the upper layer are defined by the average thickness, which is because there may be some variation in the thickness of the formation layer depending on the laying method.
[0025]
In the bottom sediment / water purification method using the bottom structure according to the present invention, after forming a lower layer made of a granular material having a high internal friction angle, an upper layer containing steelmaking slag is formed thereon. .
[0026]
Furthermore, it is preferable that the average thickness of the lower layer made of a granular material having a high internal friction angle is 10 cm or more, and the average thickness of the upper layer containing the steelmaking slag is 5 cm or more.
[0027]
The lower layer made of granular material with a high internal friction angle is good in meshing between the granular materials, so that it does not sink into the bottom mud and has a low internal friction angle even when heavy objects are loaded on the upper part. It has the property of supporting heavy objects without flowing like grains. Therefore, by forming the lower layer with a granular material having a high internal friction angle, neither the lower layer nor the upper layer is submerged in the bottom mud, and the characteristics of the upper layer can be maximized. Furthermore, since the upper layer containing the steelmaking slag does not come into direct contact with the bottom mud, consolidation due to the reaction between the steelmaking slag and the bottom mud is reduced, and the gap between the steelmaking slag becomes a suitable place for living organisms in the reef area.
[0028]
In addition, laying on the water bottom of the lower layer which consists of a granular material with a large internal friction angle, and the upper layer containing steelmaking slag can be performed by the method using a gut ship etc.
[0029]
In addition, in places where the bottom structure is locally convex due to rocks in the bottom, the thickness of the lower layer or the lower layer and the upper layer may be locally zero. The effect is not impaired.
[0030]
【Example】
Example 1
From a converter slag containing 95% of a particle size of 20 mm or more on a bottom layer made of granulated blast furnace slag with an average thickness ranging from 2 cm to 50 cm on the bottom mud of the seabed where a large amount of floating mud flows. The upper layer was formed with an average thickness of 20 cm and 50 cm, and the subduction of the upper layer into the bottom mud was investigated. The results are shown in Table 1 together with the average thickness of each layer.
[0031]
[Table 1]
As shown in Table 1, when the thickness of the converter slag was 20 cm, the blast furnace granulated slag had a thickness of 5 cm or more and the converter slag could be prevented from sinking into the bottom mud. Moreover, when the thickness of the converter slag was 50 cm, the thickness of the granulated blast furnace slag was 10 cm or more, and the converter slag could be prevented from sinking into the bottom mud.
[0033]
(Example 2)
A bottom layer of blast furnace granulated slag is formed on the bottom mud of the seabed where inflow of floating mud is 20cm thick, and the upper part of the converter slag adjusted to various particle sizes shown in Table 2 on it. The layer was formed with a thickness of 10 cm. Table 2 shows the results of observing the gaps in the upper layer visually and the presence or absence of diatoms over time.
[0034]
[Table 2]
Under all conditions, the converter slag did not sink into the bottom mud, and the effect of forming granulated blast furnace slag as the lower layer was recognized. Under the condition that the grain size of the converter slag in the upper layer was 10 mm or more and 85% or more, a gap was observed in the upper layer even after 3 years of formation, and a long-term purification effect on the bottom and water was confirmed. In addition, diatom deposition was confirmed on the surface of the converter slag, and it was confirmed that the biota was attached and recovered early.
[0036]
(Example 3)
A lower layer of granulated blast furnace slag with a thickness of 30 cm is formed on the bottom mud of the seabed where a large amount of floating mud flows, and the upper part of the converter slag adjusted to the various particle sizes shown in Table 3 above. The layer was formed with a thickness of 15 cm. Table 3 shows the results of observation of the gaps in the upper layer and the presence or absence of diatom growth over time.
[0037]
[Table 3]
Under all conditions, the converter slag did not sink into the bottom mud, and the effect of forming granulated blast furnace slag as the lower layer was recognized. Under the condition that the particle size of the converter slag in the upper layer is 20 mm or more and 90% or more (10 mm or more and 95% or more), a gap is observed in the upper layer even after 5 years of formation, and long-term purification of bottom sediment and water quality The effect was confirmed. In addition, diatom deposition was confirmed on the surface of the converter slag, and it was confirmed that the biota was attached and recovered early. It was also observed that fish such as goby lived in the gaps in the upper layer.
[0039]
Example 4
A bottom layer made of granulated blast furnace slag with a thickness of 10 cm is formed on the bottom mud of the seabed where a large amount of floating mud flows, and an upper part made of converter slag adjusted to various particle sizes as shown in Table 4 above. The layer was formed with a thickness of 5 cm. Moreover, it compared with what did not perform what aged with steam for every particle size. Table 4 shows the results of observing the gaps in the upper layer and the presence or absence of diatoms over time by visual observation.
[0040]
[Table 4]
Under all conditions, the converter slag did not sink into the bottom mud, and the effect of forming granulated blast furnace slag as the lower layer was recognized. Under the condition that the converter slag of the upper layer is aged and the particle size is 20 mm or more and 75% or more (10 mm or more and 85% or more), a gap is observed in the upper layer even after 3 years of formation. The effect of purifying bottom sediment and water quality was confirmed. In addition, diatom deposition was confirmed on the surface of the converter slag, and it was confirmed that the biota was attached and recovered early.
[0042]
In addition, by increasing the grain size of the converter slag in the upper layer, the period until the gap is not observed in the upper layer is lengthened, and the gap in the upper layer is longer in the slag converter slag. Observed across.
[0043]
【The invention's effect】
As described above, according to the present invention, there is provided a bottom structure and bottom mud that have a long-term bottom sediment / water purification effect, suppress the generation of H 2 S, and are suitable for the habitat environment of organisms in rocky areas. A method to purify the sediment and water quality of the accumulated water bottom is provided.
Claims (8)
前記下部層の平均厚さが１０ｃｍ以上であり、前記上部層の平均厚さが５ｃｍ以上であることを特徴とする水底構造。A lower layer made of a granular material having an internal friction angle of 25 ° or more, and an upper layer containing steelmaking slag thereon,
An average thickness of the lower layer is 10 cm or more, and an average thickness of the upper layer is 5 cm or more.
前記下部層の平均厚さを１０ｃｍ以上とし、前記上部層の平均厚さを５ｃｍ以上とすることを特徴とする底質・水質浄化法。A bottom layer / water purification method in which a lower layer made of a granular material having an internal friction angle of 25 ° or more is formed, and an upper layer containing steelmaking slag is formed thereon,
The bottom layer / water purification method, wherein the average thickness of the lower layer is 10 cm or more and the average thickness of the upper layer is 5 cm or more.
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| JP4945742B2 (en) * | 2004-08-06 | 2012-06-06 | 国立大学法人広島大学 | Bottom quality improving material and bottom quality improving method using the same |
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| JP4904791B2 (en) * | 2005-11-30 | 2012-03-28 | Ｊｆｅスチール株式会社 | Artificial submarine base for aquatic animal settlement / growth or farmland bottom purification |
| JP5135533B2 (en) * | 2007-01-19 | 2013-02-06 | 新日鐵住金株式会社 | Method for suppressing phosphorus elution from marine sediment |
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| US10786591B2 (en) | 2015-09-10 | 2020-09-29 | Samsung Heavy Industries Co., Ltd. | Contaminant reducing device |
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