JP3922676B2 - Incineration residue treatment method and method for producing aggregate and solidified material using incineration residue - Google Patents

Description

【００１８】
ダイオキシン類の許容値としては、オランダ、ドイツで設定されている土壌中のダイオキシン類の許容値が参考となる。オランダの場合を表２に、ドイツの場合を表３に示す。オランダでは、土壌の法的基準は設定されていないが、ガイドライン値として表２の値が１９８７年に提案された。ドイツでは、土壌中濃度の参考値が１９９１年に表３として提案されている。この参考値は強制的なものではないが、多くの州政府により実践されている。参考文献としては、環境庁が発行するダイオキシン排出抑制対策検討会報告（平成９年５月）がある。ここでＴＥＱは毒性等価換算値を指称する。
【００１９】
【表２】

【００２０】
【表３】

【００２１】
次に、本発明者等は、大型ストーカ式都市ごみ焼却炉の焼却灰を分析することにした。図１は都市ごみ焼却炉の要部構成図である。クレーン２により都市ごみをホッパー４内に投下し、都市ごみを矢印順に乾燥ストーカ６、燃焼ストーカ８、後燃焼ストーカ１０、灰出コンベア１２および灰出バンカ１４へと送る。
【００２２】
図１において、後燃焼ストーカ１０の排出口より焼却灰を採取し、また後燃焼ストーカ１０下のシュートからリドリング灰を採取した。焼却灰およびリドリング灰ともに、サンプルＡと、サンプルＢの２種類を採取した。従って、サンプルＡは焼却灰Ａとリドリング灰Ａからなり、サンプルＢは焼却灰Ｂとリドリング灰Ｂからなる。リドリンク灰は、灰の全量に対するリドリンク灰の量の割合を推定するために採取した。
【００２３】
サンプルＡおよびＢは、図２の分析フローに従って分析された。即ち、焼却灰サンプルは乾燥後、物理組成分析にかけられ、クリンカ、がれき、石、灰、ガラス、陶器、金属類の含有量が測定された。また、乾灰を５０ｍｍ角ふるいにかけて大型の不燃物、金属等を除去し、残った前処理灰を分析にかけた。
【００２４】
前処理灰をふるいにかけて粒径毎に分級する。即ち、２０ｍｍ以上の粗粒灰、５〜２０ｍｍの中粒灰、２〜５ｍｍの細粒灰、２ｍｍ以下の微粒灰の４粒径に分級し、各々についてダイオキシン類含有量、重金属類含有量、重金属類溶出量を分析した。重金属類溶出量については、環境庁告示第４６号溶出試験（環告４６号と略称する）が行なわれた。
【００２５】
表４に分析項目が一覧化されており、実施された試験に○が付されている。また、後述するように、必要な粒度に対しては固化強度テストまたは重金属安定化テストが行なわれた。
【００２６】
【表４】

【００２７】
図３にはサンプルの物理組成が示されている。例えば、サンプルＡはリドリング灰１２．４％と焼却灰８７．６％からなり、この焼却灰は４２．５％のガラ（５０ｍｍ角以上）と４５．１％の６種物理組成に分けられる。つまり、粗粒灰、中粒灰、細粒灰および微粒灰を合計したものの物理組成が前記の６種物理組成になる。サンプルＢも同様に考えてよい。
【００２８】
粗粒灰、中粒灰、細粒灰および微粒灰の分析結果が表５にまとめられている。サンプルＡおよびＢについて、粒度分布、ダイオキシン類分析、Ｐｂ分析、Ｃｄ分析、ｐＨ分析がなされた。
【００２９】
【表５】

【００３０】
表５の結果から明らかなように、粒度分布については粗粒灰と中粒灰の合計が過半数を占めている。また、ダイオキシン類については、その９０％以上が微粒灰に含まれており、粗粒灰・中粒灰・細粒灰では、表３のドイツ基準における０．００５ｎｇ−ＴＥＱ／ｇ以下であるから、土地利用に何ら制限のない安全な灰である。ドイツ基準では５ｎｇ−ＴＥＱ／ｋｇとなっており単位換算により上述の値になることを注意しておく。
【００３１】
重金属類については、細かい灰の方が含有量、溶出量ともに高い傾向がある。Ｐｂでは、粗粒灰および中粒灰の環告４６号の値は、表１の土壌環境基準値０．０１ｍｇ／ｌ以下である。また、Ｃｄでは、全ての灰で環告４６号の値は土壌環境基準値０．０１ｍｇ／ｌ未満である。ｐＨは細かい灰程高くなる傾向にある。
【００３２】
以上の結果をまとめると、粗粒灰および中粒灰はダイオキシン類および重金属類共に基準値以下である。細粒灰ではダイオキシン類は基準値以下だが、重金属類では基準値を越えている。微粒灰では、ダイオキシン類および重金属類共に基準値を越えていることが分った。
【００３３】
この分析結果が示すところは次の通りである。焼却灰を処理・処分・再利用する場合に、粗粒灰から微粒灰までの全てが含まれている焼却灰をそのまま、ダイオキシン分解処理や重金属固定処理を行うことは極めて不効率、不経済である。つまり、焼却灰を各粒度に分級し、各粒度のもつ特性に合わせて処理した方がより効果的・経済的であり、この点が本発明の中心思想である。
【００３４】
即ち、焼却灰の過半数を占める粗粒灰と中粒灰については、ダイオキシン類および重金属類が基準値以下に少ないので、加熱処理を施して無害化する必要もなく、粉砕処理も施さないで、そのまま例えば骨材として利用することができる。
【００３５】
細粒灰については、ダイオキシン類は基準値以下である一方、重金属類、特にＰｂが基準値を超える。従って、ダイオキシン類を除去するための高価な加熱処理を施す必要はないが、重金属類の溶出を防止するための適切な重金属固定処理剤を加えることが必要となる。更に、これに固化剤、例えばセメント系固化剤を加えて固化材処理をすると、軟弱土壌や浚渫土壌等の土壌固化材として利用することができる。
【００３６】
尚、細粒灰に重金属固定処理と固化材処理を施してこれを土壌固化材として利用する場合に、当該細粒灰に、前期粗粒灰と中粒灰の何れか一方又は両方に粉砕処理を施して細粒灰としたものを適宜量混合するようにしてもよい。
【００３７】
また、前記重金属処理と固化材処理を施した細粒灰に、粗粒灰と中粒灰の何れか一方又は両方を粉砕して細粒灰としたものを混合する場合に、後者の粉砕処理により形成した細粒灰に、予かじめ重金属処理と固化材処理の何れか一方又は両方を施しておくようにしてもよい。土壌固化材としての安全性がより一層向上するからである。
【００３８】
微粒灰については、ダイオキシン類が基準値を超え、且つ重金属類も基準値を超えるので、ダイオキシン類分解処理と重金属固定処理の両方を行う必要がある。ダイオキシン分解処理には溶融・焼成等の加熱処理や化学的分解法があり、重金属固定処理には重金属固定剤の投入処理等がある。
【００３９】
特に、溶融処理はダイオキシン類を分解すると同時に重金属類を固定化する作用も有するので、極めて効果的である。生成された溶融物は、例えば骨材などに利用することができる。溶融処理は設備費・ランニングコスト共に高価ではあるが、微粒灰の焼却灰に占める割合は２０％程度と低いので、焼却灰全部を溶融処理することに比し、設備費・ランニングコスト共に大幅に節約することができる。
【００４０】
【実施例】
以下に、本発明に係る焼却残渣処理方法および焼却残渣再利用品の実施例を図面とともに説明する。
【００４１】
［実施例１：焼却残渣処理方法］
図４は焼却灰を処理するフロー図である。このフロー図は大きく分けると、焼却灰排出Ｉ、前処理II、分級III およびダイオキシン分解IVの４工程からなり、その構成と動作を以下に説明する。
都市ごみ等を焼却炉２１で焼却すると、焼却灰と燃焼ガスが生成する。燃焼ガスはバグフィルタ２２および湿式有害ガス除去装置２３を通して浄化される。
【００４２】
一方、焼却灰はコンベア２４を経て、５０ｍｍのスクリーン２５ａにかけられ、粒径が５０ｍｍ以上の粗大物２５ｂは埋立処分に回される。次に補助スクリーン２５ｃと破砕装置２５ｄにより細かくして、磁選機２６により鉄２６ａを分離し、アルミ選別機２７によりアルミ２７ａを分離する。
【００４３】
鉄２６ａとアルミ２７ａを分離された焼却灰は、分級機２８に入り、ここで粒径が２０ｍｍ以上の粗粒灰、５〜２０ｍｍの中粒灰、２〜５ｍｍの細粒灰、２ｍｍ以下の微粒灰に分級される。
【００４４】
粗粒灰および中粒灰はそのまま骨材２９に利用される。細粒灰は重金属固定処理３０と固化材化処理３０ａにより固化材３０ｂとして有効利用される。
【００４５】
微粒灰は、局所集塵用バグフィルタ３１の集塵灰とともに、ダイオキシン分解装置３２に移送される。
ダイオキシン分解装置３２には、高温をかけて熱分解させる溶融炉等が使用される。
【００４６】
図５は総量１００の焼却灰が処理される場合の物質収支の一例である。○の中に書かれた数値が物質量を表わす。この例では、焼却灰総量１００は、粗大物２５ｂに４２、鉄２６ａに５、アルミ２７ａに５、骨材２９に３０、固化材３０ｂに９、ダイオキシン分解装置３２に９と流れる。粗大物２５ｂは埋立てに、鉄２６ａ・アルミ２７ａは売却もしくは埋立されるが、分級処理された残りはほとんど有効利用されることになる。この分級処理による有効利用は本発明により初めて可能となったものである。
【００４７】
［実施例２：細粒灰の土壌固化材への利用］
実施例１で分級された細粒灰に重金属固定剤を添加して重金属固定処理３０を行い、更にセメント系固化剤を添加して固化材化処理３０ａを行って土壌固化材を製造した。この土壌固化材を海底浚渫土および陸上軟弱土に各々加えて、ソイルミキサーを用いて３分間×２回混練し、φ５×１０ｃｍの供試体を成形した。詳細を表６に示す。
【００４８】
【表６】

【００４９】
細粒灰と土の比率は１：１０、１：３、１：１の３種類で、重金属固定剤の添加量は土の１０重量％である。また、セメント系固化剤の添加量は土壌固化材１ｍ³ 当りに、５２〜５８ｋｇである。
【００５０】
次に、これらの供試体の固化強度を測定するために、一軸圧縮強度試験を行った。材齢７日と２８日について試験を行ったが、２８日の方が７日より高くなり焼却残渣：海底浚渫土＝１：１０の１条件以外は材齢２８日の一軸圧宿強度は全て２ｋｇｆ／ｃｍ² 以上であり、土壌固化材として十分再利用できることが実証された。
【００５１】
更に、固化供試体に対し環告４６号による重金属溶出試験を行った。材齢７日、２８日の供試体について行ったがＰｂ溶出量およびＣｄ溶出量は全て０．０１ｍｇ／ｌ以下であった。従って、Ｐｂ、Ｃｄ共に表１の土壌環境基準を満足していることが証明された。
【００５２】
本発明は上記実施例に限定されるものではなく、本発明の技術的思想を逸脱しない範囲における種々の変形例、設計変更などをその技術的範囲内に包含するものである。
【００５３】
【発明の効果】
本発明によって、従来、焼却灰に含まれるダイオキシン類や重金属類の処理のため、焼却灰全体に高価な溶融処理を施したり、或いは多量の重金属固定剤を添加したりしていたのに対し、スクリーンという簡素な設備を附加するだけで、焼却灰を粗粒灰、中粒灰、細粒灰、微粒灰に分級し、それぞれをその粒度のもつ特性に合わせて処理し、再利用品に加工することができる。
【００５４】
また、本発明によって最終処分場への埋立量を低減することができ、高価でエネルギー消費の大きい溶融炉、焼成炉などの負荷を下げ、設備コストの低減、ランニングコストの低減を行うことができる。
従って、省エネルギーに役立ち、しかも焼却灰の再利用化を促進できる産業上有益な方法を実現した。
【図面の簡単な説明】
【図１】図１は本発明が適用される都市ごみ焼却炉の要部構成図である。
【図２】図２は本発明の分析フロー図である。
【図３】図３はサンプルの物理組成図である。
【図４】図４は実施例１の焼却灰処理フロー図である。
【図５】図５は実施例１における焼却灰の物質収支の一例である。
【符号の説明】
２はクレーン、４はホッパー、６は乾燥ストーカ、８は燃焼ストーカ、１０は後燃焼ストーカ、１２は灰出コンベア、１４は灰出バンカ、２１は焼却炉、２２はバグフィルタ、２３は湿式有害ガス除去装置、２４はコンベア、２５ａはスクリーン、２５ｂは粗大物、２５ｃは補助スクリーン、２５ｄは破砕装置、２６は磁選機、２６ａは鉄、２７はアルミ選別機、２７ａはアルミ、２８は分級機、２９は骨材、３０は重金属固定処理、３０ａは固化材化処理、３０ｂは固化剤、３１は局所集塵用バグフィルタ、３２はダイオキシン分解装置、Ｉは焼却灰排出、IIは前処理、III は分級、IVはダイオキシン分解である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating incineration residues discharged from an incinerator such as municipal waste and industrial waste. More specifically, the incineration residue is classified and processed for each particle size to increase the processing efficiency. In addition, the present invention relates to an incineration residue treatment method capable of effectively using a treated product, and an aggregate and a solidified material production method using the incineration residue.
[0002]
[Prior art]
Generally, municipal waste and industrial waste are reduced by incineration. Accordingly, a large amount of incineration residue (hereinafter also referred to as incineration ash) is discharged from the incinerator every day, and has been treated by landfill disposal methods for a long time.
However, the rapid increase in waste in recent years has led to a shortage of landfill sites, and the scattering of incinerated ash by wind has become a problem. In particular, the problem of environmental pollution such as extremely toxic dioxins contained in incineration ash and elution of heavy metals is extremely social, and various methods for replacing landfilling and effective methods have been studied.
[0003]
Among these methods, one that has attracted particular attention in recent years is a method for melting and solidifying incinerated ash, which has already been put into practical use. The volume of incinerated ash can be reduced to 1/2 to 1/3 by melting and solidifying. In addition, it is possible to prevent the elution of toxic substances such as heavy metals and to completely decompose dioxins. Since the molten slag can be reused as road material, concrete aggregate, etc., it has the effect of extending the life of the final landfill site.
However, in order to melt and solidify a large amount of incinerated ash, enormous heat energy is required, which not only increases equipment costs and running costs, but also has a problem from the viewpoint of energy saving.
[0004]
In addition, there is a method in which incinerated ash is put into a cement kiln as a part of cement raw material to make Portland cement. This method can be easily realized by commercial cement manufacturing technology, and the equipment cost is low.
However, the incineration plant and the cement factory have a locational restriction that they are considerably separated from each other, and the chlorine component present in the incineration ash has a disadvantage that it adversely affects cement quality. Therefore, it has been difficult to use incinerated ash for general-purpose Portland cement, and the use of cement has been limited.
[0005]
Further, as an inexpensive and effective method of using the incineration ash, there is a method in which the incineration ash is dried and pulverized, and an additive and cement are added thereto to form a solidifying agent. This solidifying agent can be used as a soil solidifying agent such as soft soil or sludge and can be sold at a relatively high price.
However, in this method, there is a risk that the contained heavy metals are eluted. For example, the solubility of lead has a pH dependency, and a considerable amount of lead is eluted when the pH condition is satisfied. In addition, dioxins remain without being thermally decomposed, and some dioxins are diffused into the atmosphere together with exhaust gas during dry pulverization.
[0006]
[Problems to be solved by the invention]
As described above, there are many problems in the conventional method for treating incineration residue or incineration ash. The landfill disposal method has a landfill problem, a heavy metal elution problem, and a dioxin problem, and the melt-solidification method has a large cost and energy consumption problem.
In addition, there is a problem of cement quality when used as a cement raw material, and lead elution and dioxin problems occur when used as a soil solidifying agent.
[0007]
[Means for Solving the Problems]
The present invention has been made to solve the above-mentioned drawbacks, and the incineration residue treatment method according to the invention of claim 1 includes a first step of removing large incombustibles and metals from incineration ash discharged from an incinerator. The second step of classifying the incinerated ash after removal into coarse ash having a particle size of 20 mm or more, medium ash of 5 to 20 mm, fine ash of 2 to 5 mm, and fine ash of 2 mm or less, and coarse ash, The medium ash is recovered as it is, the fine ash is recovered by a heavy metal fixing treatment, and the fine ash is composed of a third step of dioxin decomposition treatment.
[0008]
The incineration residue processing method according to the invention of claim 2 is characterized in that, in the third step of the invention of claim 1, the solidified material is subjected to solidification treatment in the fine ash.
[0009]
The method for producing a solidified material according to the invention of claim 3 is characterized in that the processed product of fine ash obtained in the third step of the invention of claim 1 or claim 2 is utilized as the solidified material. .
[0010]
According to a fourth aspect of the present invention, there is provided a method for producing a solidified material, comprising pulverizing either one or both of coarse ash and medium ash obtained in the second step of the first aspect of the invention into fine ash, It is characterized by being used by mixing with the solidifying material obtained in the invention of ( 3 ).
[0011]
According to a fifth aspect of the present invention, there is provided a method for producing a solidified material, comprising pulverizing one or both of coarse ash and medium ash obtained in the second step of the first aspect of the invention into fine ash. After either or both of heavy metal fixing treatment and solidification material treatment is applied to the granular ash, it is used by mixing with the solidification material obtained in the invention of claim 3 .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The disadvantage of the conventional method for treating incineration ash is that it has been determined that the properties of incineration ash are common to the entire incineration ash, and has been trying to process the entire incineration ash at once. Therefore, the present inventors have noticed that incinerated ash may have different properties depending on the particle size.
[0015]
Among the problems of conventional treatment methods, the elution of heavy metals and the release of dioxins are large, so we focused on the heavy metal content and dioxin content of incinerated ash, and decided to study the particle size dependence. .
That is, incineration ash is divided into coarse ash, medium ash, fine ash, and fine ash, and each heavy metal content and dioxin content is measured, and there is a significant difference for each particle size (also called particle size). If there is, it is to establish a processing method and effective use method suitable for the characteristic.
[0016]
Therefore, the standard heavy metal concentration and dioxin concentration must be determined. Since it is the mainstream to use the soil environment standard as the allowable value of the heavy metal concentration, this is shown in Table 1.
[0017]
[Table 1]

[0018]
As the permissible value of dioxins, the permissible value of dioxins in soil set in the Netherlands and Germany can be used as a reference. Table 2 shows the case of the Netherlands and Table 3 shows the case of Germany. In the Netherlands, there are no legal standards for soil, but the values in Table 2 were proposed in 1987 as guideline values. In Germany, reference values for soil concentrations were proposed in 1991 as Table 3. This reference is not compulsory, but is practiced by many state governments. As a reference, there is a dioxin emission control measure study report (May 1997) published by the Environment Agency. Here, TEQ refers to a toxicity equivalent conversion value.
[0019]
[Table 2]

[0020]
[Table 3]

[0021]
Next, the present inventors decided to analyze the incineration ash of a large stoker-type municipal waste incinerator. FIG. 1 is a configuration diagram of a main part of a municipal waste incinerator. The municipal waste is dropped into the hopper 4 by the crane 2, and the municipal waste is sent to the drying stoker 6, the combustion stoker 8, the post-combustion stoker 10, the ashing conveyor 12, and the ashing bunker 14 in the order of arrows.
[0022]
In FIG. 1, incineration ash was collected from the outlet of the post-combustion stoker 10, and ridling ash was collected from a chute under the post-combustion stoker 10. Two types of samples A and B were collected for both incineration ash and ridling ash. Therefore, sample A consists of incineration ash A and ridling ash A, and sample B consists of incineration ash B and ridling ash B. The liquor ash was collected in order to estimate the ratio of the amount of liquor ash to the total amount of ash.
[0023]
Samples A and B were analyzed according to the analysis flow of FIG. That is, the incinerated ash sample was dried and subjected to physical composition analysis, and the contents of clinker, debris, stone, ash, glass, earthenware, and metals were measured. Further, dry ash was passed through a 50 mm square sieve to remove large incombustibles, metals, etc., and the remaining pretreated ash was subjected to analysis.
[0024]
Sieve pretreated ash and classify by particle size. That is, it is classified into four particle sizes of coarse ash of 20 mm or more, medium ash of 5 to 20 mm, fine ash of 2 to 5 mm, fine ash of 2 mm or less, and dioxin content, heavy metal content for each, The elution amount of heavy metals was analyzed. Regarding the elution amount of heavy metals, the Environmental Agency Notification No. 46 dissolution test (abbreviated as Circular 46) was conducted.
[0025]
The analysis items are listed in Table 4, and the tests performed are marked with a circle. Further, as will be described later, a solidification strength test or a heavy metal stabilization test was performed for the required particle size.
[0026]
[Table 4]

[0027]
FIG. 3 shows the physical composition of the sample. For example, sample A is composed of 12.4% of ridling ash and 87.6% of incinerated ash, and this incinerated ash is divided into 42.5% of glass (50 mm square or more) and 45.1% of six physical compositions. That is, the physical composition of the sum of coarse ash, medium ash, fine ash, and fine ash is the above-described six physical compositions. Sample B may be considered similarly.
[0028]
Table 5 summarizes the analysis results of coarse ash, medium ash, fine ash and fine ash. Samples A and B were subjected to particle size distribution, dioxin analysis, Pb analysis, Cd analysis, and pH analysis.
[0029]
[Table 5]

[0030]
As is clear from the results in Table 5, with respect to the particle size distribution, the sum of coarse ash and medium ash accounts for the majority. In addition, about 90% or more of dioxins are contained in fine ash, and for coarse ash, medium ash, and fine ash, it is 0.005 ng-TEQ / g or less according to the German standard in Table 3. It is a safe ash with no restrictions on land use. It should be noted that the German standard is 5 ng-TEQ / kg, and the above value is obtained by unit conversion.
[0031]
For heavy metals, fine ash tends to be higher in both content and elution. In Pb, the value of notice 46 of coarse ash and medium ash is not more than the soil environment standard value of Table 1 of 0.01 mg / l. Moreover, in Cd, the value of Circular 46 is less than the soil environmental standard value of 0.01 mg / l for all ashes. The pH tends to be higher for fine ash.
[0032]
To summarize the above results, coarse ash and medium ash are below the standard value for both dioxins and heavy metals. For fine ash, dioxins are below the standard value, but for heavy metals, the standard value is exceeded. It was found that fine ash exceeded the standard value for both dioxins and heavy metals.
[0033]
The results of this analysis are as follows. When treating, disposing, and reusing incineration ash, it is extremely inefficient and uneconomical to carry out dioxin decomposition treatment and heavy metal fixation treatment as it is, including all of coarse ash to fine ash. is there. That is, it is more effective and economical to classify the incinerated ash into each particle size and treat it according to the characteristics of each particle size, and this is the central idea of the present invention.
[0034]
That is, for coarse ash and medium ash that account for the majority of incinerated ash, since dioxins and heavy metals are less than the standard value, there is no need to detoxify by heat treatment, without pulverization treatment, It can be used as it is, for example, as an aggregate.
[0035]
For fine ash, dioxins are below the standard value, while heavy metals, especially Pb, exceed the standard value. Therefore, it is not necessary to perform an expensive heat treatment for removing dioxins, but it is necessary to add an appropriate heavy metal fixing treatment agent for preventing elution of heavy metals. Furthermore, when a solidifying agent, for example, a cement-type solidifying agent is added thereto and treated with a solidifying material, it can be used as a soil solidifying material such as soft soil or dredged soil.
[0036]
When fine ash is subjected to heavy metal fixation treatment and solidification material treatment and used as soil solidification material, the fine ash is pulverized into either or both of the previous coarse ash and medium ash. The amount of fine ash that has been applied may be mixed as appropriate.
[0037]
In addition, when the fine ash that has been subjected to the heavy metal treatment and the solidifying material treatment is mixed with fine ash obtained by pulverizing one or both of coarse ash and medium ash, the latter pulverization treatment The fine ash formed by the above may be subjected to either one or both of heavy metal treatment and solidifying material treatment in advance. This is because the safety as a soil solidifying material is further improved.
[0038]
For fine ash, since dioxins exceed the standard value and heavy metals also exceed the standard value, it is necessary to perform both dioxin decomposition treatment and heavy metal fixing treatment. Dioxin decomposition treatment includes heat treatment such as melting and firing and chemical decomposition methods, and heavy metal fixation treatment includes input treatment of a heavy metal fixing agent.
[0039]
In particular, the melting treatment is extremely effective because it has an action of decomposing dioxins and fixing heavy metals at the same time. The generated melt can be used, for example, for aggregates. Although both the equipment cost and running cost are high in the melting treatment, the proportion of fine ash in the incineration ash is as low as about 20%, so both the equipment cost and running cost are significantly higher than the melting treatment of the entire incineration ash. Can be saved.
[0040]
【Example】
Hereinafter, examples of the incineration residue treatment method and the incineration residue reuse product according to the present invention will be described with reference to the drawings.
[0041]
[Example 1: Incineration residue treatment method]
FIG. 4 is a flowchart for processing incineration ash. This flow chart is roughly divided into four steps of incineration ash discharge I, pretreatment II, classification III, and dioxin decomposition IV, and its configuration and operation will be described below.
When municipal waste or the like is incinerated in the incinerator 21, incineration ash and combustion gas are generated. The combustion gas is purified through the bag filter 22 and the wet harmful gas removal device 23.
[0042]
On the other hand, the incinerated ash is passed through a conveyor 24 and applied to a 50 mm screen 25a, and a coarse product 25b having a particle size of 50 mm or more is sent to landfill. Next, the iron 26a is separated by the magnetic separator 26 and the aluminum 27a is separated by the aluminum sorter 27.
[0043]
The incinerated ash from which the iron 26a and the aluminum 27a are separated enters the classifier 28, where the coarse ash having a particle size of 20 mm or more, the medium ash of 5 to 20 mm, the fine ash of 2 to 5 mm, and the ash of 2 mm or less. Classified into fine ash.
[0044]
Coarse ash and medium ash are used for the aggregate 29 as they are. The fine ash is effectively used as the solidifying material 30b by the heavy metal fixing process 30 and the solidifying process 30a.
[0045]
The fine ash is transferred to the dioxin decomposition device 32 together with the dust ash from the local dust collection bag filter 31.
For the dioxin decomposition apparatus 32, a melting furnace or the like that is thermally decomposed at a high temperature is used.
[0046]
FIG. 5 is an example of a material balance when a total amount of incinerated ash is processed. The numerical value written in ○ represents the amount of substance. In this example, the total amount of incinerated ash 100 flows as 42 for the coarse product 25b, 5 for the iron 26a, 5 for the aluminum 27a, 30 for the aggregate 29, 9 for the solidified material 30b, and 9 for the dioxin decomposition device 32. The coarse material 25b is sold for landfill and the iron 26a / aluminum 27a is sold or landfilled, but the remainder of the classification treatment is almost effectively utilized. Effective use by this classification process is made possible for the first time by the present invention.
[0047]
[Example 2: Use of fine-grained ash as a soil-solidifying material]
A heavy metal fixing agent was added to the fine ash classified in Example 1 to perform heavy metal fixing treatment 30, and a cement-based solidifying agent was further added to perform solidification treatment 30a to produce a soil solidification material. This soil-solidifying material was added to each of the submarine dredged soil and the land soft soil, and kneaded twice for 3 minutes using a soil mixer to form a specimen having a diameter of 5 × 10 cm. Details are shown in Table 6.
[0048]
[Table 6]

[0049]
The ratio of fine ash and soil is three types of 1:10, 1: 3, and 1: 1, and the amount of heavy metal fixing agent added is 10% by weight of the soil. The amount of cement-based solidifying agent added is 52 to 58 kg per 1 m ³ of soil solidifying material.
[0050]
Next, in order to measure the solidification strength of these specimens, a uniaxial compressive strength test was performed. Tests were conducted for ages 7 and 28, but 28 days were higher than 7 days, and the incineration residue: submarine soil = 1: 10, except for one condition of uniaxial crushing strength of ages 28 days It was demonstrated that it is ² kgf / cm ² or more and can be sufficiently reused as a soil solidifying material.
[0051]
Furthermore, a heavy metal elution test according to Circular 46 was performed on the solidified specimen. The test was performed on specimens having a material age of 7 days and 28 days, but the Pb elution amount and the Cd elution amount were all 0.01 mg / l or less. Therefore, it was proved that both Pb and Cd satisfied the soil environmental standards shown in Table 1.
[0052]
The present invention is not limited to the above embodiments, and includes various modifications, design changes, and the like within the technical scope without departing from the technical idea of the present invention.
[0053]
【The invention's effect】
According to the present invention, for the treatment of dioxins and heavy metals contained in incineration ash, conventionally, the entire incineration ash was subjected to expensive melting treatment, or a large amount of heavy metal fixing agent was added, By simply adding a simple equipment called a screen, the incineration ash is classified into coarse ash, medium ash, fine ash, and fine ash, and each is processed according to the characteristics of the particle size and processed into reusable products. can do.
[0054]
Further, according to the present invention, the amount of landfill to the final disposal site can be reduced, and the load of a melting furnace and a baking furnace that is expensive and consumes a large amount of energy can be reduced, thereby reducing the equipment cost and the running cost. .
Therefore, an industrially useful method that can contribute to energy saving and promote the reuse of incinerated ash has been realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of a municipal waste incinerator to which the present invention is applied.
FIG. 2 is an analysis flow diagram of the present invention.
FIG. 3 is a physical composition diagram of a sample.
FIG. 4 is a flowchart of incineration ash treatment according to the first embodiment.
FIG. 5 is an example of the mass balance of incinerated ash in Example 1.
[Explanation of symbols]
2 is a crane, 4 is a hopper, 6 is a dry stoker, 8 is a combustion stoker, 10 is a post-combustion stoker, 12 is an ash conveyor, 14 is an ash bunker, 21 is an incinerator, 22 is a bag filter, and 23 is wet harmful Degassing device, 24 conveyor, 25a screen, 25b coarse, 25c auxiliary screen, 25d crushing device, 26 magnetic separator, 26a iron, 27 aluminum sorter, 27a aluminum, 28 classifier 29 is an aggregate, 30 is a heavy metal fixing process, 30a is a solidification process, 30b is a solidifying agent, 31 is a local dust collecting bag filter, 32 is a dioxin decomposition device, I is incinerated ash discharge, II is a pretreatment, III is classification and IV is dioxin decomposition.

Claims (5)

The first step of removing large incombustibles and metals from the incineration ash discharged from the incinerator, and the incineration ash after the removal of coarse ash having a particle size of 20 mm or more, 5 to 20 mm medium ash and 2 to 5 mm The second step of classifying fine ash and fine ash of 2 mm or less , coarse ash and medium ash are recovered as they are, fine ash is recovered by heavy metal fixing treatment, and fine ash is subjected to dioxin decomposition treatment An incineration residue treatment method comprising the third step.   The incineration residue treatment method according to claim 1, wherein the solidified material is treated together with the fine ash in the third step. A method for producing a solidified material, wherein the processed product of fine ash obtained in the third step of claim 1 or claim 2 is utilized as a solidified material. Either or both of coarse ash and medium ash obtained in the second step of claim 1 are pulverized into fine ash, and mixed with the solidified material obtained in claim 3 and utilized. A method for producing a solidified material. Either one or both of the coarse ash and the medium ash obtained in the second step of claim 1 are pulverized into fine ash, and either one of the heavy metal fixing treatment and the solidification treatment is applied to the fine ash, or A method for producing a solidified material, characterized in that after both are applied, the solidified material obtained in claim 3 is mixed and utilized.

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