JP4874880B2 - Manufacturing method for earthwork materials - Google Patents
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- JP4874880B2 JP4874880B2 JP2007169458A JP2007169458A JP4874880B2 JP 4874880 B2 JP4874880 B2 JP 4874880B2 JP 2007169458 A JP2007169458 A JP 2007169458A JP 2007169458 A JP2007169458 A JP 2007169458A JP 4874880 B2 JP4874880 B2 JP 4874880B2
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Description
本発明は、土壌環境基準を超える量の重金属類を溶出し易い土壌、スラッジ、汚泥、焼却灰など土壌環境基準を満足しない重金属類含有物（本発明においては、これらを総称して『土壌環境基準不適合物』と言う。）を資源として有効利用した土工資材の製造方法に関するものである。
The present invention includes heavy metals that do not satisfy soil environmental standards such as soil, sludge, sludge, incinerated ash, etc. that easily elute heavy metals in amounts exceeding soil environmental standards. refers to the reference non-conforming product. ") in which about the earth moving method of manufacturing materials that effectively utilize the resources.
現在、汚染土壌、スラッジ、汚泥、焼却灰と言った重金属類含有物の多くは、そのまま地中に埋めたりセメントや樹脂を用いて固化するなどして、廃棄物として埋め立て処分されている。しかし、これらの焼却灰などには、鉛（Ｐｂ），砒素（Ａｓ），六価クロム（Ｃｒ6+）などに代表される人体に有害な重金属類が多く含まれており、これらの重金属類が、埋め立て処分後に溶出する可能性がある。そのため、これらの重金属類の溶出防止処理が必要になる。 Currently, many heavy metal-containing materials such as contaminated soil, sludge, sludge, and incinerated ash are landfilled as waste by being buried in the ground as they are or solidified with cement or resin. However, these incineration ash and the like contain a lot of heavy metals harmful to the human body represented by lead (Pb), arsenic (As), hexavalent chromium (Cr 6+ ), and the like. May elute after landfill disposal. Therefore, the elution prevention process of these heavy metals is needed.
また、近年、焼却灰などの重金属類含有物を単に廃棄物として埋め立て処分するのではなく、資源として有効に利用しようとする技術も開発されつつあるが、このような焼却灰などの資源化においては、廃棄物処理法の埋立基準より数倍厳しい環境庁告示の土壌環境基準を守ることが要求され、六価クロムなどの重金属類の資源化物からの溶出防止技術はさらに重要である。 In addition, in recent years, technologies are being developed to effectively use heavy metal-containing materials such as incineration ash as landfills instead of simply landfilling them as waste. Therefore, it is required to observe the soil environmental standards announced by the Environment Agency, which is several times stricter than the landfill standards of the Waste Management Law, and technology for preventing elution from resources of heavy metals such as hexavalent chromium is even more important.
上記のように廃棄物として埋め立て処分をするにしろ、資源化を図るにしろ、重金属類の溶出防止は避けて通れない重要な事項であることから、様々な研究がなされている。
例えば、重金属類を溶出するおそれのある重金属類含有汚染土壌又は汚泥に対し、鉄鋼スラグを散布することにより、又は混合することにより、汚染土壌又は汚泥中の重金属類を安定化する技術が特許文献１に開示されている。
Regardless of whether it is disposed of in landfill as a waste or as a resource as described above, prevention of elution of heavy metals is an unavoidable important matter, and various studies have been conducted.
For example, a technique for stabilizing heavy metals in contaminated soil or sludge by spraying or mixing steel slag to contaminated soil or sludge containing heavy metals that may elute heavy metals 1 is disclosed.
また、資源化物を得る際の重金属類の溶出防止技術としては、例えば、焼却灰をベントナイトなどと混合、攪拌、焼成した後、電磁波の照射或いはオゾン処理することにより、ベントナイトなどの部分に重金属類を吸着・担持させる作用を強化し、重金属類の溶出防止を図った人工骨材・軽量骨材等の製造方法が特許文献２に開示されている。また、焼却灰に粘結材と組成調整材とを混合し、さらに還元剤として石炭又はコークスを加え、得られた混合物を粉砕、成形、要すれば乾燥し、次いで焼成することにより、焼成物中に炭素を一定量（０．２〜０．５重量％）残存させ、焼成物中のクロムを三価に保持し、六価クロムの溶出防止を図った技術が特許文献３に開示されている。さらに、焼却炉又は溶融炉より発生する飛灰が有する重金属を不溶化処理するにおいて、該飛灰にＣａＯ，ＳｉＯ2 ，Ａｌ2 Ｏ3 を主成分とする電気炉鉱滓より副生される還元期スラグを添加するとともに、りん酸を添加し混練する技術が特許文献４に開示されている。 In addition, as a technique for preventing the elution of heavy metals when obtaining resources, for example, after mixing incinerated ash with bentonite, stirring, and firing, irradiation with electromagnetic waves or ozone treatment makes heavy metals in parts such as bentonite. Patent Document 2 discloses a method for producing artificial aggregates, lightweight aggregates, etc., in which the action of adsorbing and supporting the steel is strengthened and the elution of heavy metals is prevented. Moreover, a caking material is obtained by mixing a caking agent and a composition adjusting material with incineration ash, adding coal or coke as a reducing agent, pulverizing, shaping, drying if necessary, and then firing. Patent Document 3 discloses a technique in which a certain amount (0.2 to 0.5% by weight) of carbon is left therein, chromium in the fired product is kept trivalent and elution of hexavalent chromium is prevented. Yes. Furthermore, in the insolubilization treatment of heavy metals in fly ash generated from incinerators or melting furnaces, reduction slag produced as a by-product from electric furnace slag containing CaO, SiO 2 , Al 2 O 3 as main components in the fly ash Patent Document 4 discloses a technique in which phosphoric acid is added and kneaded together with the addition of.
しかしながら、先ず上記特許文献１に開示された鉄鋼スラグを散布、或いは混合する技術にあっては、広範囲又は大量の汚染土壌などに対して簡易に実施できる技術ではあるが、その重金属類の溶出防止効果にはバラツキがあり、処理後の汚染土壌などを資源として有効に利用しようとする際には、環境庁告示の土壌環境基準を満足し得ない場合もあり、改善の余地があった。 However, first, in the technique of spraying or mixing the steel slag disclosed in the above-mentioned Patent Document 1, although it is a technique that can be easily carried out over a wide area or a large amount of contaminated soil, prevention of elution of the heavy metals There are variations in the effects, and when trying to effectively use contaminated soil after treatment as a resource, there are cases in which the soil environment standards announced by the Environment Agency may not be satisfied, and there is room for improvement.
また、上記特許文献２に開示された電磁波の照射やオゾン処理を行う方法にあっては、重金属類の溶出防止効果は十分と考えられ、焼却灰などの資源化が可能となるものの、処理のための特別な装置が必要であり、コスト面において課題を有するものであった。また、大量の焼成物に対して万遍なく電磁波の照射やオゾン処理を行うことは困難であり、実施面においても課題を有するものであった。 In addition, in the method of performing electromagnetic wave irradiation and ozone treatment disclosed in Patent Document 2, it is considered that the effect of preventing elution of heavy metals is sufficient, and resources such as incineration ash can be recycled, For this reason, a special device is required, and there is a problem in cost. In addition, it is difficult to uniformly irradiate a large quantity of the fired product with electromagnetic wave irradiation or ozone treatment, and there is a problem in terms of implementation.
さらに、上記特許文献３に開示された焼却灰などの原料に還元剤として石炭又はコークスを加え、還元雰囲気下で焼成を行うことにより６価クロムなどの溶出を防止する技術にあっては、焼成物中に残存する炭素それ自体は強力な還元力を有するものではないため、焼成物からの重金属類の溶出防止効果を長期に渡って維持する面では未だ十分な技術ではなく、また工程も複雑であることから、やはりコスト面において課題を有するものであった。 Furthermore, in the technique for preventing elution of hexavalent chromium and the like by adding coal or coke as a reducing agent to a raw material such as incinerated ash disclosed in Patent Document 3 and firing in a reducing atmosphere, Since the carbon remaining in the product itself does not have a strong reducing power, it is not yet a sufficient technique for maintaining the effect of preventing the elution of heavy metals from the fired product over a long period of time, and the process is complicated. Therefore, it still has a problem in cost.
また、上記特許文献４に開示された飛灰に対して還元期スラグ及びりん酸を添加し混練する技術にあっては、上記特許文献１と同様に、重金属類の溶出防止効果にバラツキがあり、処理後の飛灰などを資源として有効に利用しようとする際には、環境庁告示の土壌環境基準を満足し得ない場合もあり、やはり改善の余地があった。 In addition, in the technique of adding and reducing kneaded slag and phosphoric acid to the fly ash disclosed in Patent Document 4, there is variation in the effect of preventing the elution of heavy metals as in Patent Document 1. When trying to use fly ash after treatment effectively as a resource, there may be cases where the soil environment standards announced by the Environment Agency may not be satisfied, and there is still room for improvement.
上記したように、重金属類を溶出する土壌環境基準不適合物の資源化を図るに際して、重金属類の溶出防止技術として、簡便でかつ効果的な方法は未だ見出されていないのが現状である。
また、埋め立て処分をするにしろ、資源化を図るにしろ、前記土壌環境基準不適合物である焼却灰中でも焼却飛灰、キルンダストと言ったダスト類は、処理中に微粒子が飛散し易く、ハンドリング性も悪いことから取り扱いに苦慮していた。
As described above, there is no simple yet effective method for preventing the elution of heavy metals when resources for non-conforming soil environment standards that elute heavy metals have been found.
In addition, whether it is disposed of in landfills or recycled, dust such as incineration fly ash and kiln dust, which are incompatible with the soil environmental standards, easily disperses fine particles during processing, and is easy to handle. It was difficult to handle because it was bad.
一方、スラグ、石炭灰、再生骨材副生物などの産業副産物の発生を抑制し、或いは産業副産物を有効利用することにより、廃棄物として処理しなければならない産業副産物を減容し、環境問題解決に貢献するという観点も重要である。
このような産業副産物の一つとして、鉄スクラップから鋼を製造する際に大量に発生する電気炉スラグがある。電気炉スラグには、生成過程の違いにより酸化スラグと還元スラグとがあり、酸化スラグは溶鋼中に酸素を吹き込んで不要な成分を酸化させる酸化精錬時に生成されるスラグであり、還元スラグは酸化精錬終了後のスラグを排出し、新たに還元剤や石灰などを装入し、溶鋼中の酸素を除去する還元精錬時に生成されるスラグである。
On the other hand, by suppressing the generation of industrial by-products such as slag, coal ash and recycled aggregate by-products, or by effectively using industrial by-products, the volume of industrial by-products that must be treated as waste is reduced, and environmental problems are solved. It is also important to contribute to
One such industrial by-product is electric furnace slag that is generated in large quantities when steel is produced from iron scrap. There are two types of electric furnace slag: oxidized slag and reduced slag due to differences in the production process. Oxidized slag is slag produced during oxidation refining by blowing oxygen into molten steel to oxidize unnecessary components, and reduced slag is oxidized. This slag is produced during reductive refining, in which slag after refining is discharged, and a reducing agent or lime is newly added to remove oxygen in the molten steel.
全国では、電気炉酸化スラグが年間約２００万トン、還元スラグが約１００万トン発生しており、その内、電気炉酸化スラグは化学的に安定で、水に溶解したり、崩壊したりすることがないので、その一部が路盤材やコンクリート骨材などとして利用されているが、電気炉還元スラグは多量の遊離ＣａＯを含有し、これが水和反応を起すときに体積膨脹を起して崩壊する、いわゆる「アトフケ」現象がみられるため用途が少なく、その大部分が廃棄物として埋め立て処分されているが現状であり、有効な利用技術の開発が強く望まれている。 Nationwide, about 2 million tons of electric furnace oxidation slag and about 1 million tons of reduction slag are generated annually. Of these, electric furnace oxidation slag is chemically stable and dissolves or disintegrates in water. Some of them are used as roadbed materials, concrete aggregates, etc., but the electric furnace reducing slag contains a large amount of free CaO, which causes volume expansion when it causes a hydration reaction. Since the so-called “Atofuke” phenomenon that collapses is seen, there are few uses, and most of them are landfilled as waste, but at present, development of effective utilization techniques is strongly desired.
本発明は、上述した背景技術に鑑み成されたものであって、その目的は、産業副産物である電気炉還元スラグの特性を活かしてその有効利用を図るとともに、土壌環境基準不適合物を資源として用いた重金属類、特に六価クロムが溶出し難い土工資材の製造方法を提供することにある。
The present invention has been made in view of the background art described above, and its purpose is to make effective use of the characteristics of electric furnace reducing slag, which is an industrial by-product, and to use non-conforming material as a resource for soil environment standards. An object of the present invention is to provide a method for producing earthwork materials in which the heavy metals used, particularly hexavalent chromium, are difficult to elute.
本発明者等は、上記した目的を達成すべく鋭意研究を進めた結果、所定粒径以下に粉砕した特定の鉱物組成の電気炉還元スラグはその水硬性及び還元性が飛躍的に向上したものとなり、該電気炉還元スラグの粉砕物を土壌環境基準不適合物に混合することにより該土壌環境基準不適合物（特にダスト類）のハンドリング性が改善されるとともに、重金属類の溶出を長期に渡って防止（著しく低減）できることを見出し、本発明を完成させた。
As a result of earnest research to achieve the above-mentioned object, the inventors of the present invention have dramatically improved the hydraulic properties and reducibility of electric furnace reduced slag having a specific mineral composition pulverized to a predetermined particle size or less. By mixing the pulverized material of the electric furnace reducing slag with the non-conforming material of the soil environment standard, the handling property of the non-conforming material (especially dusts) of the soil environment is improved, and elution of heavy metals over a long period of time. It was found that it can be prevented (remarkably reduced), and the present invention has been completed.
即ち、本発明に係る土工資材の製造方法は、次のものである。
〔１〕 電気炉還元スラグが、構成鉱物として少なくともマイエナイトを５０重量％以上、オルダマイトを５重量％以上含有することと、該電気炉還元スラグを、最大粒径１００μｍ以下に粉砕することと、該電気炉還元スラグ粉砕物と土壌環境基準不適合物と水との混合物を、造粒或いは成形することを特徴とする、土工資材の製造方法。
〔２〕 上記混合物中における電気炉還元スラグ粉砕物と土壌環境基準不適合物との割合が、重量比で１：５〜１：１であることを特徴とする、〔１〕に記載の土工資材の製造方法。
〔３〕 上記混合物中に含まれる水の量が、１５〜２５重量％であることを特徴とする、〔１〕又は〔２〕に記載の土工資材の製造方法。
なお、本明細書において『最大粒径』とは、篩の残分が５重量％以内となる目開き寸法をいう。
That is, the method for manufacturing an earthwork material according to the present invention is as follows.
[1] The electric furnace reduced slag contains at least 50% by weight of mayenite and 5% by weight or more of alumite as constituent minerals, the electric furnace reduced slag is pulverized to a maximum particle size of 100 μm or less, A method for producing an earthwork material, comprising granulating or molding a mixture of ground slag of electric furnace reduced slag, non-conformity with soil environmental standards, and water .
[2] The earthwork material according to [1], wherein the ratio of the pulverized electric furnace reduced slag and the nonconformity with the soil environment standard in the mixture is 1: 5 to 1: 1 by weight. Manufacturing method.
[3] The method for producing an earthwork material according to [1] or [2], wherein the amount of water contained in the mixture is 15 to 25% by weight .
In the present specification, the “maximum particle size” refers to an opening size with which the remainder of the sieve is within 5% by weight.
上記した本発明によれば、産業副産物である電気炉還元スラグの有効利用を図ることができるとともに、土壌環境基準不適合物を資源として用いた重金属類、特に六価クロムが溶出し難い土工資材を提供することができる。
より具体的には、本発明によれば、特定の鉱物組成、即ち少なくともマイエナイトを５０重量％以上、オルダマイトを５重量％以上含有する電気炉還元スラグを最大粒径（篩の残分が５重量％以内となる目開き寸法）１００μｍ以下に粉砕して用いるため、該電気炉還元スラグ中に存在する水硬性を有するマイエナイト、還元性を有するオルダマイトがそれぞれ有効にその機能を発揮するものとなり、該粉砕された電気炉還元スラグを混合した土壌環境基準不適合物の固化によるハンドリング性が改善された造粒或いは成形と、六価クロムなどの重金属類の還元による無害化による有害な重金属類の溶出防止（著しい低減）を合わせて行うことができ、また混合された余剰の（すぐに重金属類の還元に消費されなかった）還元性を有する電気炉還元スラグ中のオルダマイトは、造粒物或いは成形物自体に還元の余力を持たせることとなり、該造粒物或いは成形物中に残存する重金属類、特に六価クロムの溶出を長期に渡って防止することができる。また、本発明の実施は容易であり、得られる造粒物や成形物はサンドコンパクション、路盤材、盛り土材、埋め戻し材などの土工資材として有効に利用することができる。この重金属の溶出を防止し安全な土工資材を提供する方法は、土壌環境基準不適合物が胚胎する現地に、電気炉還元スラグを持ち込み、簡易プラントなどにより実施することが可能であることから、現地での土壌浄化にも容易に適用できる。この際、電気炉還元スラグを粉砕しないままにしておけば、保管も可能である。
According to the present invention described above, it is possible to effectively use the electric furnace reducing slag, which is an industrial by-product, and to use an earthwork material that is difficult to elute heavy metals, particularly hexavalent chromium, using a non-conforming material of soil environmental standards as a resource. Can be provided.
More specifically, according to the present invention, an electric furnace reduced slag containing a specific mineral composition, that is, at least 50% by weight of mayenite and 5% by weight or more of oldite, has a maximum particle size ( the balance of the sieve is 5% by weight). %) (Mesh size within 100%) pulverized to 100 μm or less, so that the mayenite having hydraulic properties and the alumite having reducibility present in the electric furnace reducing slag effectively exhibit their functions, Granulation or molding with improved handling by solidifying non-conforming soil environment standards mixed with pulverized electric furnace reducing slag, and prevention of harmful heavy metals from elution by detoxification by reducing heavy metals such as hexavalent chromium (Significant reduction) can be performed together, and the mixed surplus electricity (which was not immediately consumed by the reduction of heavy metals) has reducibility Oldite in the reduced slag will give the granulated product or molded product itself a reduction capacity, and prevent elution of heavy metals remaining in the granulated product or molded product, particularly hexavalent chromium, over a long period of time. can do. In addition, the present invention is easy to implement, and the resulting granulated product and molded product can be effectively used as earthwork materials such as sand compaction, roadbed material, embankment material, and backfill material. This method of preventing the elution of heavy metals and providing safe earthwork materials can be carried out by using a simple plant, etc., by bringing electric furnace reducing slag to the site where non-conformity with soil environmental standards occurs. It can be easily applied to soil remediation. At this time, if the electric furnace reducing slag is not crushed, it can be stored.
以下、上記した本発明に係る土工資材の製造方法の実施の形態を、詳細に説明する。
Hereinafter, an embodiment of a method for manufacturing an earthwork material according to the present invention will be described in detail.
本発明による土工資材の製造方法は、電気炉還元スラグが、構成鉱物として少なくともマイエナイトを５０重量％以上、オルダマイトを５重量％以上含有することと、該電気炉還元スラグを、最大粒径１００μｍ以下に粉砕することと、該電気炉還元スラグ粉砕物と土壌環境基準不適合物と水との混合物を、造粒或いは成形するものである。より具体的には、上記特定の鉱物組成の電気炉還元スラグと土壌環境基準不適合物とを湿式で最大粒径１００μｍ以下に混合粉砕し、該混合粉砕物を造粒或いは成形する、或いは、上記特定の鉱物組成の電気炉還元スラグと土壌環境基準不適合物とを最大粒径１００μｍ以下に混合粉砕した後に加水し、該加水した混合粉砕物を造粒或いは成形する、或いは、上記特定の鉱物組成の電気炉還元スラグを最大粒径１００μｍ以下に粉砕し、該電気炉還元スラグ粉砕物と土壌環境基準不適合物とを湿式で混合し、該混合物を造粒或いは成形する、或いは、上記特定の鉱物組成の電気炉還元スラグを最大粒径１００μｍ以下に粉砕し、該電気炉還元スラグ粉砕物と土壌環境基準不適合物とを混合した後に加水し、該加水した混合物を造粒或いは成形するものである。
なお、本明細書においていう上記『最大粒径』とは、先にも記載したように、篩の残分が５重量％以内となる目開き寸法をいう。
In the method for producing an earthwork material according to the present invention, the electric furnace reduced slag contains at least 50% by weight of mayenite and 5% by weight or more of alumite as constituent minerals, and the electric furnace reduced slag has a maximum particle size of 100 μm or less. And a mixture of the electric furnace reduced slag pulverized product, the soil environment standard nonconforming material, and water is granulated or molded. More specifically, the electric furnace reduction slag and soil environment standard incompatibility of the specific mineral composition were mixed and pulverized to less than or equal to the maximum particle size 100μm wet, granulated or molding the ground mixture or the Electric furnace reduced slag having a specific mineral composition and non-conformity with soil environmental standards are mixed and pulverized to a maximum particle size of 100 μm or less, and then the mixed pulverized product is granulated or molded, or the above specific mineral composition The electric furnace reduced slag is pulverized to a maximum particle size of 100 μm or less, and the pulverized electric furnace reduced slag and the non-conforming material of the soil environment standard are wet mixed, and the mixture is granulated or molded, or the specific mineral electric furnace reduction slag composition was pulverized to less than or equal to the maximum particle size 100 [mu] m, adding water after mixing the electric furnace reduction slag pulverized product and soil environment standard incompatible, mixtures granulated or molded to that the pressurized water It is intended.
The “maximum particle size” referred to in the present specification refers to the opening size that makes the remainder of the sieve within 5% by weight, as described above.
本発明において使用する上記土壌環境基準不適合物には、環境庁告示の土壌環境基準〔鉛（Ｐｂ）０．０１ｍｇ／Ｌ以下，砒素（Ａｓ）０．０１ｍｇ／Ｌ以下，六価クロム（Ｃｒ6+）０．０５ｍｇ／Ｌ以下等〕を超える量の重金属類が溶出する虞のある汚染土壌、スラッジ、汚泥、焼却灰などが広く含まれる。具体的には、汚染土壌としては、廃棄物の焼却処理施設の周辺や、化学工業、冶金関連の工場跡地などから掘削された土壌などが挙げられ、土壌自体の種類は特には限定されず、粘土質、砂質、火山灰などのいずれでもよい。また、スラッジとしては、製紙スラッジ、アルミナスラッジなどが挙げられ、汚泥としては、建設汚泥、建設発生土（水比の高いもの）などが挙げられる。また、焼却灰としては、火力発電所や石炭焚きボイラーなどから発生する石炭灰、都市ごみ焼却炉から排出される焼却主灰や焼却飛灰、更には種々の焼成炉から発生するキルンダストなどが典型的な例であるが、重金属類を含む焼却灰であれば、これらに限定されない。
上記の中でも、本発明において特に対象となる土壌環境基準不適合物は、ハンドリング性の悪い焼却飛灰、キルンダストなどのダスト類である。
The above-mentioned nonconformity with the soil environment standard used in the present invention includes soil environment standards (lead (Pb) 0.01 mg / L or less, arsenic (As) 0.01 mg / L or less, hexavalent chromium (Cr 6 + ) 0.05 mg / L or less etc.] are widely included in contaminated soil, sludge, sludge, incinerated ash and the like that may cause heavy metals to be eluted. Specific examples of contaminated soil include soil excavated from the vicinity of waste incineration facilities, chemical industry, metallurgical factory sites, etc. The type of soil itself is not particularly limited, Any of clay, sand and volcanic ash may be used. Examples of the sludge include papermaking sludge and alumina sludge. Examples of the sludge include construction sludge and construction generated soil (having a high water ratio). Incineration ash typically includes coal ash generated from thermal power plants and coal-fired boilers, main ash and incineration fly ash discharged from municipal waste incinerators, and kiln dust generated from various calcination furnaces. Although it is a specific example, if it is incineration ash containing heavy metals, it will not be limited to these.
Among the above, the soil environment standard nonconformity which is particularly targeted in the present invention is dusts such as incineration fly ash and kiln dust having poor handling properties.
一方、電気炉還元スラグは、通常その化学組成は、ＣａＯを４５〜６０重量％、Ａｌ2Ｏ3を３０〜４０重量％、ＳＯ3を５〜１０重量％、ＭｇＯを５〜１０重量％、ＳｉＯ2を１〜１０重量％、Ｆｅ2Ｏ3を０．５〜２．５重量％、Ｃｒ2Ｏ3を０．１〜０．５重量％程度含むものであるが、本発明において用いる電気炉還元スラグは、特に構成鉱物として少なくともマイエナイトを５０重量％以上、オルダマイトを５重量％以上含有するものである。これは、マイエナイトは水硬性を有する鉱物であり、該マイエナイトの含有量が５０重量％に満たない場合には、ハンドリング性が良好な程度にまで固化した造粒物或いは成形物が得られ難いためである。一方、オルダマイトは還元剤として機能するものであり、該オルダマイトの含有量が少ない電気炉還元スラグでは、還元による重金属類の溶出防止効果が十分に発揮されないためである。かかる観点から、マイエナイトを６０重量％以上、オルダマイトを１０重量％以上含有する電気炉還元スラグであることが特に好ましい。なお、マイエナイト（Mayenite）は１２ＣａＯ・７Ａｌ2Ｏ3で示される急硬性のある鉱物である。オルダマイト（Oldhamite ）は（Ｃａ，Ｍｇ）Ｓで示される還元性を有する鉱物であり、天然には隕石のような極度に還元状態で生成した岩石にしか確認されていないものである。 On the other hand, the electric furnace reduction slag, usually its chemical composition, the CaO 45 to 60 wt%, the Al 2 O 3 30 to 40 wt%, SO 3 and 5-10 wt%, the MgO 5-10% by weight, the SiO 2 1 to 10 wt%, the Fe 2 O 3 0.5 to 2.5 wt%, but the Cr 2 O 3 are those containing about 0.1 to 0.5 wt%, an electric furnace reduction used in the present invention slag, in particular at least mayenite 50 wt% or more minerals are those containing Orudamaito 5 wt% or more. This is because mayenite is a mineral having hydraulic properties, and when the content of the mayenite is less than 50% by weight, it is difficult to obtain a granulated product or a molded product solidified to a good handling property. It is . Meanwhile, Orudamaito is intended to function as a reducing agent, in an electric furnace reduction slag containing a small amount of the Orudamaito, elution preventing effect of heavy metals by reduction is due not be sufficiently exhibited. From this viewpoint, an electric furnace reducing slag containing 60% by weight or more of mayenite and 10% by weight or more of alumite is particularly preferable. In addition, mayenite (Mayenite) is a rapid-hardening mineral represented by 12CaO · 7Al 2 O 3 . Oldhamite is a mineral having a reducing property represented by (Ca, Mg) S, and is naturally only found in rocks produced in an extremely reduced state, such as meteorites.
本発明においては、上記電気炉還元スラグ中のマイエナイトの水硬性、或いはオルダマイトの還元性を十分に発揮させる観点、また土壌環境基準不適合物との混合性及びハンドリング性の改善などの観点から、該電気炉還元スラグを最大粒径１００μｍ以下、好ましくは７５μｍ以下に粉砕する。この電気炉還元スラグの粉砕は、上記したように土壌環境基準不適合物との湿式或いは乾式混合粉砕により行ってもよく、また電気炉還元スラグ単独で行ってもよい。混合粉砕する場合には、混合粉砕物の最大粒径が１００μｍ以下となるようにする。この場合も混合粉砕物中に粒径１００μｍ以下の電気炉還元スラグが多く存在することとなるので、前記水硬性や還元性は発揮される。 In the present invention, from the viewpoint of fully exhibiting the hydraulic properties of the mayenite in the electric furnace reducing slag, or the reducing ability of the alumite, and the improvement of the mixability and handling properties with non-conformants with soil environment standards, The electric furnace reducing slag is pulverized to a maximum particle size of 100 μm or less, preferably 75 μm or less. The pulverization of the electric furnace reduced slag may be performed by wet or dry mixed pulverization with a soil environment standard nonconforming material as described above, or may be performed solely by the electric furnace reduced slag. When mixing and pulverizing, the maximum particle size of the mixed and pulverized product is set to 100 μm or less. In this case as well, since a large amount of electric furnace reducing slag having a particle size of 100 μm or less is present in the mixed pulverized product, the hydraulic properties and reducing properties are exhibited.
上記電気炉還元スラグの粉砕は、湿式で行うか乾式で行うか、また土壌環境基準不適合物との混合粉砕で行うか単独粉砕で行うかにより、公知の種々の粉砕機、例えばボールミル、振動ミル、媒体攪拌ミル、ジェットミルなどの装置の中から適宜選択して用いればよく、これらの装置を単独で使用してもよく、また多段に構成して使用してもよい。 The electric furnace reducing slag is pulverized by a wet pulverization method, a dry pulverization method, a mixed pulverization method with a non-conforming material or a single pulverization method. In addition, a device such as a medium stirring mill or a jet mill may be appropriately selected and used, and these devices may be used alone or in a multistage configuration.
土壌環境基準不適合物については、その種類によって事前に別途予備粉砕が必要であるものと必要でないものとが存在する。例えば土壌環境基準不適合物として焼却飛灰、キルンダストなどのダスト類を用いる場合には、微粉であるために事前の予備粉砕の必要はなく、そのまま電気炉還元スラグとの混合粉砕を行ってもよく、また、別途粉砕された電気炉還元スラグにそのまま混合してもよい。混合は湿式でも乾式でもよい。一方、土壌環境基準不適合物として焼成クリンカなどを用いる場合には、電気炉還元スラグとの混合性、また粉砕機の物理的制約の観点から、少なくとも最大粒径２０ｍｍ以下程度に単独粉砕しておくことが好ましい。粉砕機としては、上記した電気炉還元スラグの粉砕機として先に例示したものの中から適宜選択して用いればよい。 As for the non-conforming material of soil environment standard, there are some that need to be preliminarily pulverized in advance and some that are not necessary. For example, when dust such as incineration fly ash or kiln dust is used as a nonconforming material for soil environmental standards, it is fine powder, so there is no need for preliminary pulverization in advance, and mixing pulverization with electric furnace reducing slag may be performed as it is. Moreover, you may mix as it is in the electric furnace reduction | restoration slag pulverized separately. Mixing may be wet or dry. On the other hand, when a baked clinker or the like is used as a nonconforming material for soil environmental standards, it is pulverized separately to at least a maximum particle size of about 20 mm or less from the viewpoint of miscibility with electric furnace reducing slag and physical restrictions of the pulverizer. It is preferable. The pulverizer may be appropriately selected from those exemplified above as the pulverizer for the electric furnace reducing slag.
本発明においては、電気炉還元スラグと土壌環境基準不適合物とを混合粉砕或いは混合する。この電気炉還元スラグと土壌環境基準不適合物との混合割合は、重量比で、電気炉還元スラグ：土壌環境基準不適合物の比が１：５〜１：１が好ましい。これは、上記重量比よりも電気炉還元スラグの割合が少ない場合には、ハンドリング性が良好な程度にまで固化した造粒物或いは成形物が得られ難いとともに、還元による重金属類の溶出防止効果が十分に発揮されないために好ましくない。一方、土壌環境基準不適合物の混合割合が上記重量比よりも少ない場合には、効率的な土壌環境基準不適合物の資源としての利用が図れない。かかる観点から、電気炉還元スラグ：土壌環境基準不適合物の混合重量比は、１：３〜１：１がさらに好ましい。 In the present invention, the electric furnace reducing slag and the soil environment standard nonconforming material are mixed and ground or mixed. The mixing ratio of the electric furnace reduced slag and the soil environment standard nonconforming material is preferably a weight ratio of 1: 5 to 1: 1. This is because, when the ratio of electric furnace reducing slag is smaller than the above weight ratio, it is difficult to obtain a granulated product or molded product solidified to a good handling property, and the effect of preventing elution of heavy metals by reduction Is not preferable because it is not sufficiently exhibited. On the other hand, when the mixing ratio of the soil environment standard non-conformity is less than the above weight ratio, efficient use of the soil environment standard non-conformity as a resource cannot be achieved. From this viewpoint, the mixing weight ratio of the electric furnace reducing slag: the non-conformity with the soil environment standard is more preferably 1: 3 to 1: 1.
上記電気炉還元スラグと土壌環境基準不適合物との混合は、電気炉還元スラグの粉砕と同時に混合する混合粉砕の形で行ってもよく、また別途粉砕した電気炉還元スラグと土壌環境基準不適合物とを混合してもよい。また、この混合粉砕或いは混合は、それぞれ湿式で行っても乾式で行ってもよい。混合装置としては、混合粉砕で行う場合には上記したボールミル、振動ミル、媒体攪拌ミル、ジェットミルなどの装置から適宜選択して用いればよい。また粉砕した電気炉還元スラグと土壌環境基準不適合物とを単に混合する場合には、パグミキサー、リボンミキサーなどの混合装置から適宜選択して用いればよい。 The mixing of the electric furnace reduced slag and the non-conforming material with the soil environment standard may be performed in the form of mixed pulverization mixed simultaneously with the pulverization of the electric furnace reducing slag. And may be mixed. Further, the mixing and pulverization or mixing may be performed either wet or dry. As the mixing device, when performing mixing and pulverization, the above-described devices such as a ball mill, a vibration mill, a medium stirring mill, and a jet mill may be appropriately selected and used. In addition, when the pulverized electric furnace reducing slag and the non-conforming material for soil environmental standards are simply mixed, they may be appropriately selected from a mixing apparatus such as a pug mixer and a ribbon mixer.
また、本発明においては、上記電気炉還元スラグと土壌環境基準不適合物との混合粉砕物或いは混合物は、造粒或いは成形して土工資材として用いる。この造粒或いは成形する混合粉砕物或いは混合物中に含まれる水の量は、１５〜２５重量％が好ましい。これは、水の含有量が少な過ぎる場合には水和反応が遅く造粒或いは成形が困難なものとなる。逆に水の含有量が多過ぎる場合には流動化するために好ましくない。かかる観点から、水の含有量は１７〜２３重量％がより好ましい。上記混合粉砕物或いは混合物中の水の含有量の調整は、水量が不足する場合は加水することにより行えばよく、湿式処理して水量が多過ぎる場合は適宜蒸発させることにより行えばよい。これらの水分調整は、従来の方法によればよい。 In the present invention, the mixed pulverized product or mixture of the electric furnace reducing slag and the non-conforming material of the soil environment standard is granulated or molded and used as an earthwork material. The amount of water contained in the granulated or molded mixed pulverized product or mixture is preferably 15 to 25% by weight. If the water content is too small, the hydration reaction is slow and granulation or molding becomes difficult. On the other hand, when the content of water is too large, it is not preferable because it fluidizes. From this viewpoint, the water content is more preferably 17 to 23% by weight. The water content in the mixed pulverized product or the mixture may be adjusted by adding water when the amount of water is insufficient, and may be appropriately evaporated when wet processing is performed and the amount of water is excessive. These moisture adjustments may be performed by a conventional method.
得られた電気炉還元スラグと土壌環境基準不適合物との混合粉砕物或いは混合物は、適量の水分が存在することにより電気炉還元スラグ中に存在する水硬性を有するマイエナイトの作用によって固化し塊状化する。したがって、この塊状化に際して、用途に応じて該混合粉砕物或いは混合物をパンペレタイザーのような造粒機に入れて造粒してもよく、またブリケッタのような成形機により成形してもよい。造粒物或いは成形物の形や大きさは、使用目的に合わせて種々の形態を選択できるが、例えば路盤材として用いる場合は、直径数ｍｍ〜数ｃｍの造粒物或いは成形物とすることができる。
また、必要に応じて、細骨材、シリカヒューム等の混和材、繊維状物、減水剤や増粘剤、無機塩等の本発明の目的を阻害するものでなければ、第三成分としてこれらを添加混合した後、造粒或いは成形を行ってもよい。
The resulting mixed pulverized product or mixture of electric furnace reduced slag and non-conforming soil environment standards is solidified and agglomerated by the action of the mayenite having hydraulic properties in the electric furnace reduced slag due to the presence of an appropriate amount of moisture. To do. Therefore, at the time of this agglomeration, the mixed pulverized product or mixture may be granulated by putting it in a granulator such as a pan pelletizer, or may be molded by a molding machine such as a briquetter. The shape and size of the granulated product or molded product can be selected from various forms according to the purpose of use. For example, when it is used as a roadbed material, it should be a granulated product or molded product having a diameter of several mm to several cm. Can do.
If necessary, these may be used as a third component if they do not impair the object of the present invention, such as fine aggregates, admixtures such as silica fume, fibrous materials, water reducing agents, thickeners, and inorganic salts. After adding and mixing, granulation or molding may be performed.
得られた造粒物或いは成形物は、固化によって重金属類が溶出し難いものとなるとともに、該造粒物或いは成形物中に存在する還元性を有するオルダマイトの作用によって重金属類が還元され、有害な重金属類の溶出が防止（著しく低減）される。
例えば、六価クロムは、下記の（１）式の反応により生成したＨ2 Ｓにより無害な三価クロムに還元され、有害な六価クロムの溶出が防止されると解釈される。
ＣａＳ ＋ ２Ｈ2 Ｏ → Ｃａ（ＯＨ）2 ＋ Ｈ2 Ｓ〔還元剤〕 ・・・（１）
また、造粒物或いは成形物中に残存した余剰の（すぐに重金属類の還元に消費されなかった）還元性を有するオルダマイトは、造粒物或いは成形物自体に還元の余力を持たせることとなり、該造粒物或いは成形物中に残存する重金属類、特に六価クロムの溶出を長期に渡って防止することができる。
The obtained granulated product or molded product is hard to elute heavy metals due to solidification, and heavy metals are reduced by the action of reducing alumite present in the granulated product or molded product. Of heavy metals is prevented (remarkably reduced).
For example, it is interpreted that hexavalent chromium is reduced to harmless trivalent chromium by H 2 S produced by the reaction of the following formula (1) and elution of harmful hexavalent chromium is prevented.
CaS + 2H 2 O → Ca (OH) 2 + H 2 S [reducing agent] (1)
Further, surplus reductive oldite remaining in the granulated product or molded product (which was not immediately consumed by the reduction of heavy metals) gives the granulated product or molded product itself a reduction capacity. Further, elution of heavy metals remaining in the granulated product or molded product, particularly hexavalent chromium, can be prevented over a long period of time.
上記のようにして得られた造粒物或いは成形物は、有害な重金属類の溶出が少なく、また固化によって適度の強度を有するハンドリング性が良好なものとなるため、サンドコンパクション、路盤材、盛り土材、埋め戻し材などの土工資材として好適に用いることができる。 The granulated product or molded product obtained as described above has little elution of harmful heavy metals and has good handling properties with appropriate strength by solidification, so that it is possible to obtain sand compaction, roadbed material, embankment. It can be suitably used as earthwork materials such as wood and backfill materials.
次に、本発明を見出した試験例を記載する。
−使用材料−
・『電気炉還元スラグ』
（Ａ） Ｔ１社の電気炉還元スラグ（マイエナイト含有量５０重量％，オルダマイト含有量５重量％，最大粒径３００μｍ）
使用した電気炉還元スラグ（Ａ）の主な化学組成を表１にスラグ（Ａ）として示す。
（Ｂ） Ｔ２社の電気炉還元スラグ（マイエナイト含有量６０重量％，オルダマイト含有量７重量％，最大粒径３００μｍ）
使用した電気炉還元スラグ（Ｂ）の主な化学組成を表１にスラグ（Ｂ）として示す。
（Ｃ） Ｔ３社の電気炉還元スラグ（マイエナイト含有量４６重量％，オルダマイト含有量３重量％，最大粒径３００μｍ）
使用した電気炉還元スラグ（Ｃ）の主な化学組成を表１にスラグ（Ｃ）として示す。
（ａ） 人工軽量骨材の粉砕品〔砒素（Ａｓ）０．０３ｍｇ／Ｌ溶出，最大粒径５００μｍ〕
使用した土壌環境基準不適合物（ａ）の主な化学組成を表２に示す。
（ｂ） キルンダスト〔六価クロム（Ｃｒ6+）０．０７ｍｇ／Ｌ，最大粒径１００μｍ〕
使用した土壌環境基準不適合物（ｂ）の主な化学組成を表３に示す。
-Materials used-
・ Electric furnace reduction slag
(A) Electric furnace reducing slag of T1 company (mayenite content 50% by weight, alumite content 5% by weight, maximum particle size 300 μm)
The main chemical composition of the used electric furnace reducing slag (A) is shown in Table 1 as slag (A).
(B) Electric furnace reducing slag of company T2 (mayenite content 60% by weight, alumite content 7% by weight, maximum particle size 300 μm)
The main chemical composition of the used electric furnace reducing slag (B) is shown in Table 1 as slag (B).
(C) Electric furnace reducing slag of T3 company (mayenite content 46% by weight, alumite content 3% by weight, maximum particle size 300 μm)
The main chemical composition of the electric furnace reducing slag (C) used is shown in Table 1 as slag (C).
(A) Artificial lightweight aggregate pulverized product (arsenic (As) 0.03 mg / L elution, maximum particle size 500 μm)
Table 2 shows the main chemical composition of the soil environment standard nonconformity (a) used.
(B) Kiln dust [hexavalent chromium (Cr 6+ ) 0.07 mg / L, maximum particle size 100 μm]
Table 3 shows the main chemical composition of the non-conforming material (b).
−試験例−
〔試験例１〕
上記電気炉還元スラグ（Ａ）１０ｇと、土壌環境基準不適合物（ａ）５０ｇとをディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて湿式混合粉砕し、最大粒径（篩の残分が４重量％となった目開き寸法）１００μｍの混合粉砕試料のスラリーを得た。得られたスラリーを直ちに乾燥機に入れ水分を蒸発させ、水の含有量を２３重量％に調整した試料を作製した。
〔試験例２〕
上記電気炉還元スラグ（Ｂ）１５ｇと、土壌環境基準不適合物（ｂ）５０ｇとをディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて乾式混合粉砕し、最大粒径（篩の残分が５重量％となった目開き寸法）１００μｍの混合粉砕試料を得た。得られた混合粉砕試料に２０ｇの水道水を添加混合し、水の含有量を２３重量％に調整した試料を作製した。
〔試験例３〕
上記電気炉還元スラグ（Ｂ）をディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて最大粒径（篩の残分が３重量％となった目開き寸法）１００μｍに粉砕した。続いて、上記土壌環境基準不適合物（ａ）５０ｇに、前記粉砕した電気炉還元スラグ（Ｂ）１０ｇ、水道水１８ｇそれぞれ添加し、湿式混合（ビニール袋で５分程シェイク）し、水の含有量を２３重量％に調整した試料を作製した。
〔試験例４〕
上記電気炉還元スラグ（Ａ）をディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて最大粒径（篩の残分が５重量％となった目開き寸法）８０μｍに粉砕し、次いで、上記土壌環境基準不適合物（ｂ）５０ｇに、前記粉砕した電気炉還元スラグ（Ａ）１５ｇを混合（ビニール袋で３分程シェイク）した。その後、該混合試料に２０ｇの水道水を添加混合し、水の含有量を２３重量％に調整した試料を作製した。
〔試験例５〕
上記電気炉還元スラグ（Ｂ）１０ｇと、土壌環境基準不適合物（ｂ）５０ｇとをディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて乾式混合粉砕し、最大粒径（篩の残分が３重量％となった目開き寸法）１５０μｍの混合粉砕試料を得た。得られた混合粉砕試料に１８ｇの水道水を添加混合し、水の含有量を２３重量％に調整した試料を作製した。
〔試験例６〕
上記土壌環境基準不適合物（ａ）５０ｇに、上記電気炉還元スラグ（Ａ）を粉砕することなく最大粒径３００μｍのまま１０ｇ混合（ビニール袋で３分程シェイク）した後、該混合試料に１８ｇの水道水を添加混合し、水の含有量を２３重量％に調整した試料を作製した。
〔試験例７〕
上記電気炉還元スラグ（Ｃ）１０ｇと、土壌環境基準不適合物（ａ）５０ｇとをディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて湿式混合粉砕し、最大粒径（篩の残分が４重量％となった目開き寸法）１００μｍの混合粉砕試料のスラリーを得た。得られたスラリーを直ちに乾燥機に入れ水分を蒸発させ、水の含有量を２３重量％に調整した試料を作製した。
〔試験例８〕
上記電気炉還元スラグ（Ｃ）をディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて最大粒径（篩の残分が５重量％となった目開き寸法）１００μｍに粉砕した。続いて、上記土壌環境基準不適合物（ｂ）５０ｇに、前記粉砕した電気炉還元スラグ（Ｃ）１０ｇ、水道水１８ｇそれぞれ添加し、湿式混合（ビニール袋で５分程シェイク）し、水の含有量を２３重量％に調整した試料を作製した。
〔試験例９〕
上記電気炉還元スラグ（Ａ）７ｇと、土壌環境基準不適合物（ａ）５０ｇとをディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて湿式混合粉砕し、最大粒径（篩の残分が３重量％となった目開き寸法）１００μｍの混合粉砕試料のスラリーを得た。得られたスラリーを直ちに乾燥機に入れ水分を蒸発させ、水の含有量を２３重量％に調整した試料を作製した。
〔試験例１０〕
上記電気炉還元スラグ（Ｂ）をディスク型振動ミル（川崎重工業社製；Ｔ−１００）を用いて最大粒径（篩の残分が４重量％となった目開き寸法）１００μｍに粉砕した。続いて、上記土壌環境基準不適合物（ｂ）５０ｇに、前記粉砕した電気炉還元スラグ（Ｂ）１０ｇ、水道水７ｇそれぞれ添加し、湿式混合（ビニール袋で５分程シェイク）し、水の含有量を１０重量％に調整した試料を作製した。
-Test example-
[Test Example 1]
The electric furnace reducing slag (A) 10 g and the soil environment standard nonconformity (a) 50 g were wet-mixed and pulverized using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100), and the maximum particle size (of the sieve A slurry of a mixed pulverized sample having an opening size of 100 μm with a balance of 4% by weight was obtained. The obtained slurry was immediately put into a drier to evaporate water, and a sample was prepared in which the water content was adjusted to 23% by weight.
[Test Example 2]
The electric furnace reducing slag (B) 15 g and the soil environment standard nonconformity (b) 50 g were dry-mixed and crushed using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100), and the maximum particle size (sieving A mixed pulverized sample having an opening size of 100 μm with a remaining amount of 5% by weight was obtained. A sample in which 20 g of tap water was added to and mixed with the obtained mixed and ground sample to adjust the water content to 23% by weight was prepared.
[Test Example 3]
The electric furnace reducing slag (B) was pulverized to 100 μm using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100) to a maximum particle size (aperture size where the balance of the sieve was 3% by weight). Subsequently, 10 g of the pulverized electric furnace reducing slag (B) and 18 g of tap water are added to 50 g of the soil environment standard nonconforming material (a), respectively, and wet mixing (shaking for about 5 minutes with a plastic bag) is performed. A sample with the amount adjusted to 23% by weight was prepared.
[Test Example 4]
The electric furnace reducing slag (A) was pulverized to 80 μm using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100) to a maximum particle size (aperture size with a sieve residue of 5% by weight), Next, 15 g of the pulverized electric furnace reducing slag (A) was mixed with 50 g of the soil environment standard nonconforming material (b) (shaking for about 3 minutes with a plastic bag). Thereafter, 20 g of tap water was added to the mixed sample and mixed to prepare a sample in which the water content was adjusted to 23% by weight.
[Test Example 5]
The electric furnace reducing slag (B) 10 g and the soil environment standard nonconformity (b) 50 g were dry-mixed and pulverized using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100), and the maximum particle size (of sieve A mixed pulverized sample having a mesh size of 150 μm was obtained. 18 g of tap water was added to and mixed with the obtained mixed pulverized sample to prepare a sample in which the water content was adjusted to 23% by weight.
[Test Example 6]
50 g of the soil environment standard nonconforming material (a) was mixed with 10 g of the electric furnace reducing slag (A) with a maximum particle size of 300 μm without pulverization (shake for 3 minutes with a plastic bag), and then 18 g of the mixed sample was added. Was added and mixed to prepare a sample in which the water content was adjusted to 23% by weight.
[Test Example 7]
10 g of the electric furnace reducing slag (C) and 50 g of the soil environment standard nonconformity (a) were wet mixed and pulverized using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100), and the maximum particle size (of the sieve A slurry of a mixed pulverized sample having an opening size of 100 μm with a balance of 4% by weight was obtained. The obtained slurry was immediately put into a drier to evaporate water, and a sample was prepared in which the water content was adjusted to 23% by weight.
[Test Example 8]
The electric furnace reducing slag (C) was pulverized to 100 μm using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100) to a maximum particle size (aperture size where the balance of the sieve was 5% by weight). Subsequently, 10 g of the pulverized electric furnace reducing slag (C) and 18 g of tap water are added to 50 g of the soil environment standard nonconforming material (b), respectively, and wet mixed (shaking for about 5 minutes with a plastic bag) to contain water. A sample with the amount adjusted to 23% by weight was prepared.
[Test Example 9]
7 g of the electric furnace reducing slag (A) and 50 g of soil environment standard nonconforming material (a) were wet-mixed and pulverized using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100), and the maximum particle size (of the sieve A slurry of a mixed pulverized sample having an opening size of 100 μm with a balance of 3% by weight was obtained. The obtained slurry was immediately put into a drier to evaporate water, and a sample was prepared in which the water content was adjusted to 23% by weight.
[Test Example 10]
The electric furnace reducing slag (B) was pulverized to 100 μm using a disk-type vibration mill (manufactured by Kawasaki Heavy Industries, Ltd .; T-100) with a maximum particle size (aperture size where the balance of the sieve was 4% by weight). Subsequently, 10 g of the pulverized electric furnace reducing slag (B) and 7 g of tap water are added to 50 g of the soil environment standard nonconforming material (b), respectively, and wet mixed (shaking for about 5 minutes with a plastic bag) to contain water. A sample was prepared with the amount adjusted to 10% by weight.
−重金属類の溶出試験−
得られた各試料を２４時間放置した後、固化物を解砕し、該解砕物からの重金属類の溶出量を測定した。なお、各重金属類の溶出量は、上記したＪＩＳ Ｋ ０１０２（１９９８）に準拠してそれぞれ測定した。
測定結果を表４に記載する。
After each sample obtained was allowed to stand for 24 hours, the solidified product was crushed, and the elution amount of heavy metals from the crushed product was measured. The amount of elution of each heavy metal was measured in accordance with the above-described JIS K 0102 (1998).
The measurement results are shown in Table 4.
−結 果−
上記の試験より、電気炉還元スラグを焼却灰などの土壌環境基準不適合物に混合することにより、該混合物からの重金属類の溶出を低減できることがわかる。この際、少なくとも電気炉還元スラグを最大粒径１００μｍ以下に粉砕したものを用いる必要があることがわかる。また、混合する電気炉還元スラグは、構成鉱物として少なくともマイエナイトを５０重量％以上、オルダマイトを５重量％以上含有するものであることが好ましく、また、電気炉還元スラグと土壌環境基準不適合物との混合割合は、重量比で、電気炉還元スラグ：土壌環境基準不適合物の比が１：５以上であることが好ましいことがわかる。
-Result-
From the above test, it can be understood that elution of heavy metals from the mixture can be reduced by mixing the electric furnace reducing slag with a soil environment standard nonconforming material such as incineration ash. At this time, it is understood that at least electric furnace reducing slag needs to be pulverized to a maximum particle size of 100 μm or less. Moreover, it is preferable that the electric furnace reduced slag to be mixed contains at least 50% by weight of mayenite and 5% by weight or more of alumite as constituent minerals. It can be seen that the mixing ratio is preferably a weight ratio, and the ratio of electric furnace reducing slag: soil environment standard nonconformity is 1: 5 or more.
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