JP2008272591A - Method for treating ashes containing heavy metal - Google Patents
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本発明は重金属含有灰の処理方法に係り、特に、重金属含有灰を硫酸バンド、鉄塩及びリン酸系重金属固定化剤で処理して、処理物からの重金属の溶出を抑制する方法に関する。 The present invention relates to a method for treating heavy metal-containing ash, and more particularly to a method for treating heavy metal-containing ash with a sulfate band, an iron salt and a phosphate-based heavy metal immobilizing agent to suppress elution of heavy metal from the treated product.
一般家庭ごみや産業廃棄物を焼却炉で焼却した際や、直接溶融又はガス化溶融した際、焼却残渣を溶融又は焼成した際や製鋼電気炉の操業の際には、排ガスに同伴して煤塵（以下、これを「重金属含有灰」と称す。）が発生する。排ガス中には、揮散された鉛やカドミウム等の重金属を含むダストや塩化水素（ＨＣｌ）、硫黄酸化物（ＳＯＸ）等の強酸性のガスが含まれている。このため、排ガスは、これらを除去した後、大気中に放出される。飛灰とはこの排ガスの処理後に集塵器によって捕捉されて排出されるダスト分であり、その組成は排ガスに施した処理によって異なり、各々、処理法毎に下記２種に大別できる。 When general household waste or industrial waste is incinerated in an incinerator, directly or gasified and melted, when incineration residue is melted or fired, or when operating a steelmaking electric furnace, dust is accompanied by exhaust gas. (Hereinafter, this is referred to as “heavy metal-containing ash”). The exhaust gas contains dust containing heavy metals such as volatilized lead and cadmium, and strongly acidic gas such as hydrogen chloride (HCl) and sulfur oxide (SO X ). For this reason, after removing these, exhaust gas is discharged | emitted in air | atmosphere. Fly ash is dust that is captured and discharged by the dust collector after the treatment of the exhaust gas, and its composition varies depending on the treatment applied to the exhaust gas, and can be roughly classified into the following two types for each treatment method.
一つは、排ガス中のＨＣｌやＳＯＸ等の強酸性ガスを、消石灰等のアルカリ粉末を加えて中和した後、集塵器によって捕捉されて排出される飛灰であり、この飛灰は、焼却炉で揮散された重金属と中和反応生成物の他に、未反応（過剰分）の消石灰等のアルカリ粉末が含まれているので、強アルカリ性を示し、アルカリ飛灰と呼ばれている。 One is fly ash that is neutralized by adding alkaline powder such as slaked lime to strong acid gas such as HCl and SO X in the exhaust gas, and is then captured and discharged by a dust collector. In addition to heavy metals volatilized in the incinerator and neutralization reaction products, alkali powder such as unreacted (excess) slaked lime is included, so it shows strong alkalinity and is called alkali fly ash .
もう一つは、排ガス中のダストを第１集塵器で除去した後に、苛性ソーダ等のアルカリ水溶液で洗浄したり、第２集塵器上流にアルカリ剤粉末を吹き込むことによって、酸性ガスを中和（吸収）除去する方法で、第１集塵器から排出される飛灰であり、この飛灰はほぼ中性ないし弱酸性を示し、中性飛灰ないし酸性飛灰と呼ばれている。 The other is to neutralize the acid gas by removing dust in the exhaust gas with the first dust collector and then washing with alkaline aqueous solution such as caustic soda or blowing alkaline agent powder upstream of the second dust collector. It is fly ash discharged from the first dust collector by a method of (absorption) removal, and this fly ash exhibits almost neutral or weak acidity and is called neutral fly ash or acidic fly ash.
これらの重金属含有灰は、埋立て、地盤工事等に有効利用されるか、或いは廃棄処分されるが、重金属を含むことから、重金属含有灰の有効利用又は廃棄に当っては、含有される重金属の溶出を防止する処理を施す必要がある。 These heavy metal-containing ash is effectively used for land reclamation, ground construction, etc., or is disposed of, but since it contains heavy metal, heavy metal contained in the effective use or disposal of heavy metal-containing ash It is necessary to carry out a treatment to prevent elution of.
特に、アルカリ飛灰は未反応の消石灰等のアルカリも多く含むため、溶出液のｐＨが高く、鉛などが溶出し易い。このため、アルカリ飛灰については、特に、重金属の溶出防止処理が重要となる。 In particular, alkaline fly ash contains a large amount of alkali such as unreacted slaked lime, so that the pH of the eluate is high and lead and the like are easily eluted. For this reason, with regard to alkaline fly ash, in particular, a heavy metal elution prevention treatment is important.
従来、このような重金属含有灰の処理方法として、キレート系重金属固定化剤を主体として添加する方法が多く採用されており、この際、中和剤を添加することも行われているが、キレート剤が空気酸化により、劣化して長期にわたる溶出抑制ができない恐れがある。 Conventionally, as a method for treating such heavy metal-containing ash, a method of mainly adding a chelating heavy metal fixing agent has been adopted, and at this time, a neutralizing agent has also been added. The agent may deteriorate due to air oxidation and may not be able to suppress elution over a long period of time.
特開平９−１４１２２６号では重金属含有灰に硫酸バンド及びリン酸系重金属固定化剤を加えて混練している。硫酸バンドはアルカリ成分を中和する作用を奏する。 In JP-A-9-141226, a sulfate band and a phosphate heavy metal fixing agent are added to a heavy metal-containing ash and kneaded. The sulfuric acid band acts to neutralize the alkali component.
同号には、硫酸バンド及びリン酸系重金属固定化剤は水と共に同時に灰に添加されてもよく、水溶液として添加されてもよいと記載されている。 In the same publication, it is described that the sulfate band and the phosphate heavy metal fixing agent may be added to the ash together with water or may be added as an aqueous solution.
特開平９−２９９９０５号には硫酸バンド、リン酸塩、キレート系重金属固定化剤及び還元性鉄塩を重金属含有灰に添加する方法が記載されている。同号では、硫酸バンド及びリン酸塩は粉末として使用してもよく水分散状態で使用してもよいと記載されている。 Japanese Patent Application Laid-Open No. 9-299905 describes a method of adding a sulfuric acid band, a phosphate, a chelate heavy metal fixing agent and a reducing iron salt to heavy metal-containing ash. In the same publication, it is described that the sulfate band and phosphate may be used as a powder or in an aqueous dispersion state.
特開２００４−２０９３７２号には、還元性鉄塩及び硫酸バンドの水溶液よりなる重金属固定化剤が記載されている。 Japanese Patent Application Laid-Open No. 2004-209372 describes a heavy metal immobilizing agent comprising an aqueous solution of a reducing iron salt and a sulfuric acid band.
特開２００５−５８９４２号には、好ましくはそれぞれ液状のリン酸系重金属固定化剤とキレート系重金属固定化剤とを重金属含有灰に添加する方法が記載されている。しかし、液状重金属固定化剤のみでは、添加量が多い場合、混練物がスラリー状になり、取扱いが困難になるため、十分な重金属の固定機能が得られないという問題がある。
本発明は、液状の重金属固定化剤や中和剤のみを重金属含有灰に添加する場合よりも長期にわたって重金属の溶出を抑制することができる重金属含有灰の処理方法を提供することを目的とする。 An object of the present invention is to provide a method for treating heavy metal-containing ash that can suppress elution of heavy metal over a longer period of time than when only a liquid heavy metal fixing agent or neutralizing agent is added to heavy metal-containing ash. .
本発明の重金属含有灰の処理方法は、重金属含有灰に、粉状重金属固定化剤と液状重金属固定化剤と水とを添加して混練する重金属含有灰の処理方法であって、該粉状重金属固定化剤が硫酸バンド、或いは硫酸バンド及び鉄系薬剤を含み、該液状重金属固定化剤が硫酸バンド及びリン酸系重金属固定化剤を含むことを特徴とするものである。 The method for treating heavy metal-containing ash of the present invention is a method for treating heavy metal-containing ash by adding and kneading a powdery heavy metal fixing agent, a liquid heavy metal fixing agent, and water to the heavy metal-containing ash, The heavy metal immobilizing agent includes a sulfuric acid band, or a sulfuric acid band and an iron-based chemical, and the liquid heavy metal immobilizing agent includes a sulfuric acid band and a phosphoric acid-based heavy metal immobilizing agent.
本発明では、重金属含有灰に粉状重金属固定化剤と液状重金属固定化剤とを添加するようにしており、重金属の溶出を長期にわたって十分に抑制することができる。これは、液状重金属固定化剤が重金属固定に速効性を有しており、一方、処理物中の粉状重金属固定化剤は重金属固定に遅効的であるためと推察される。 In the present invention, the powdery heavy metal fixing agent and the liquid heavy metal fixing agent are added to the heavy metal-containing ash, and elution of heavy metals can be sufficiently suppressed over a long period of time. This is presumably because the liquid heavy metal immobilizing agent has a rapid effect on immobilizing heavy metals, while the powdered heavy metal immobilizing agent in the treated product is slow in immobilizing heavy metals.
また、粉状硫酸バンド及び液状硫酸バンドを併用することによりアルカリ性重金属含有灰を中和する作用が十分に奏され、重金属の固定が安定する。 In addition, the combined use of the powdered sulfuric acid band and the liquid sulfuric acid band has a sufficient effect of neutralizing the alkaline heavy metal-containing ash, and the fixing of the heavy metal is stabilized.
以下、本発明についてさらに詳細に説明する。 Hereinafter, the present invention will be described in more detail.
本発明は、各種の重金属含有灰の処理に適用可能であり、上記背景技術に記載のいずれの飛灰にも適用できるが、アルカリ飛灰など、環境庁告示１３号試験によるｐＨが１２以上の重金属含有灰の処理に好適である。 The present invention can be applied to the treatment of various heavy metal-containing ash, and can be applied to any fly ash described in the background art above, but the pH by the Environmental Agency Notification No. 13 test such as alkali fly ash is 12 or more. Suitable for treatment of heavy metal-containing ash.
本発明では、重金属含有灰に、硫酸バンド、或いは、硫酸バンド及び鉄系薬剤を含む粉状重金属固定化剤と、硫酸バンド及びリン酸系重金属固定化剤を含む液状重金属固定化剤とを添加する。 In the present invention, a heavy metal-containing ash is added with a sulfuric acid band, or a powdery heavy metal immobilizing agent containing a sulfuric acid band and an iron-based chemical, and a liquid heavy metal immobilizing agent containing a sulfuric acid band and a phosphoric acid-based heavy metal immobilizing agent. To do.
この鉄系薬剤としては、硫酸第一鉄、塩化第一鉄などの還元性鉄塩や、ポリ硫酸鉄、鉄粉が挙げられるが、硫酸第一鉄などの還元性鉄塩が好ましい。 Examples of the iron-based drug include reducible iron salts such as ferrous sulfate and ferrous chloride, polyiron sulfate, and iron powder. Reductive iron salts such as ferrous sulfate are preferable.
粉状重金属固定化剤としては、硫酸バンドを純分で１０〜１００％特に２０〜８０％及び還元性鉄塩を純分で１０〜９０％特に２０〜８０％を含むことが好ましい。なお、本明細書において％は重量％を示す。 The powdery heavy metal immobilizing agent preferably contains 10 to 100%, particularly 20 to 80%, and 10 to 90%, particularly 20 to 80%, pure iron of the reducing iron salt, and pure iron. In the present specification, “%” represents “% by weight”.
粉状重金属固定化剤は、重金属含有灰１００重量部に対し０．５〜３０重量部特に１〜１５重量部添加されることが好ましい。 The powdery heavy metal fixing agent is preferably added in an amount of 0.5 to 30 parts by weight, particularly 1 to 15 parts by weight, based on 100 parts by weight of the heavy metal-containing ash.
液状重金属固定化剤は、上記の通り、硫酸バンドとリン酸系重金属固定化剤とを含む。このリン酸系重金属固定化剤としては、リン酸又はその塩が用いられ、このうち、リン酸としては正リン酸や次亜リン酸、メタ亜リン酸、ピロ亜リン酸、正亜リン酸、次リン酸、メタリン酸、ピロリン酸、三リン酸、縮合リン酸が挙げられ、リン酸塩としては、これらのリン酸の塩、第１リン酸塩、第２リン酸塩が挙げられる。 As described above, the liquid heavy metal immobilizing agent includes a sulfuric acid band and a phosphate heavy metal immobilizing agent. As the phosphoric acid heavy metal immobilizing agent, phosphoric acid or a salt thereof is used. Among these, phosphoric acid includes orthophosphoric acid, hypophosphorous acid, metaphosphorous acid, pyrophosphorous acid, orthophosphorous acid. Hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and condensed phosphoric acid. Examples of the phosphate include salts of these phosphoric acids, primary phosphates, and secondary phosphates.
これらの中でも、特に正リン酸（Ｈ3ＰＯ4）、リン酸二水素一ナトリウム（ＮａＨ2ＰＯ4）、リン酸一水素二ナトリウム（Ｎａ2ＨＰＯ4）、縮合リン酸等を好適に使用することができる。 Among these, orthophosphoric acid (H 3 PO 4 ), monosodium dihydrogen phosphate (NaH 2 PO 4 ), disodium monohydrogen phosphate (Na 2 HPO 4 ), condensed phosphoric acid and the like are preferably used. be able to.
液状重金属固定化剤としては、硫酸バンドを純分で１〜５０％特に５〜３０％及びリン酸系重金属固定化剤を純分で１〜７５％特に２〜６０％を含む水溶液又は分散液が好ましい。 The liquid heavy metal immobilizing agent is an aqueous solution or dispersion containing 1 to 50%, particularly 5 to 30%, and 1 to 75%, especially 2 to 60%, of a phosphoric acid heavy metal immobilizing agent. Is preferred.
液状重金属固定化剤の重金属含有灰への添加量は、液状重金属固定化剤の硫酸バンド及びリン酸系重金属固定化剤の純分の合計として、重金属含有灰１００重量部に対し０．５〜５０重量部特に３〜３０重量部程度が好ましい。 The amount of the liquid heavy metal fixing agent added to the heavy metal-containing ash is 0.5 to 100 parts by weight of the heavy metal-containing ash as a total of the sulfuric acid band and the phosphate-based heavy metal fixing agent of the liquid heavy metal fixing agent. 50 parts by weight, particularly about 3 to 30 parts by weight, is preferable.
本発明では、重金属含有灰に対しさらにキレート剤を含む重金属固定化剤（以下キレート系重金属固定化剤という）を添加してもよく、これにより、キレートとの結合が強いＨｇ等の重金属の溶出をさらに抑制することができる。キレート系重金属固定化剤としては、ジチオカルバミン酸系重金属固定化剤が挙げられ、具体的には、ジエチルジチオカルバミン酸及びその塩類（例えばナトリウム塩等）、ピペラジンジチオカルバミン酸及びその塩類、ポリアミンジチオカルバミン酸及びその塩類などがある。これらのキレート系重金属固定化剤は１種を単独で用いても、２種以上を併用しても良い。この中でも、取り扱い性の面から、液体としてのジチオカルバミン酸塩水溶液が好適に用いられる。 In the present invention, a heavy metal immobilizing agent further containing a chelating agent (hereinafter referred to as a chelating heavy metal immobilizing agent) may be added to the heavy metal-containing ash, thereby elution of heavy metals such as Hg having strong binding to the chelate. Can be further suppressed. Examples of chelate heavy metal immobilizing agents include dithiocarbamic acid based heavy metal immobilizing agents. Specifically, diethyl dithiocarbamic acid and its salts (for example, sodium salt), piperazine dithiocarbamic acid and its salts, polyamine dithiocarbamic acid and its There is salt. These chelate heavy metal immobilizing agents may be used alone or in combination of two or more. Among these, from the viewpoint of handleability, a dithiocarbamate aqueous solution as a liquid is preferably used.
このようなジチオカルバミン酸系重金属固定化剤の添加量は、重金属含有灰１００重量部に対し固形分として３重量部以下、例えば０．００１〜３重量部程度が好適であり、好ましくは２０〜６０重量％濃度の水溶液として添加して混練される。 The addition amount of such a dithiocarbamic acid heavy metal fixing agent is preferably 3 parts by weight or less, for example, about 0.001 to 3 parts by weight, preferably 20 to 60 parts by weight as solid content with respect to 100 parts by weight of heavy metal-containing ash. It is added and kneaded as an aqueous solution having a concentration by weight.
本発明では、重金属含有灰に対しまず粉状重金属固定化剤を添加して混合した後、液状重金属固定化剤を添加して混練することが好ましい。キレート系重金属固定化剤を添加する場合、液状重金属固定化剤を添加してから添加するのが好ましいが、それよりも前であってよく、同時であってもよい。キレート系重金属固定化剤と液状重金属固定化剤とを混合して添加してもよい。 In the present invention, it is preferable to first add and mix the powdery heavy metal fixing agent to the heavy metal-containing ash, and then add and knead the liquid heavy metal fixing agent. When the chelating heavy metal immobilizing agent is added, it is preferably added after the liquid heavy metal immobilizing agent is added, but it may be earlier or simultaneously. A chelate heavy metal fixing agent and a liquid heavy metal fixing agent may be mixed and added.
粉状重金属固定化剤を液状重金属固定化剤よりも先に添加するのは、粉状重金属固定化剤と重金属含有灰は粉状であり、水分が添加されると均一に混合できなくなるため、水分が添加される前に粉状重金属固定化剤と重金属含有灰を粉状同士で先に混合し、混練成型機投入前に均一化した状態にするためである。そのため、重金属含有灰を液状重金属固定化剤と混練するための混練成型機に移送する搬送コンベア等の移送手段において、重金属含有灰に粉状重金属固定化剤を添加することが、粉状同士の混合が良好になる点で好ましい。 The powdered heavy metal fixing agent is added before the liquid heavy metal fixing agent because the powdered heavy metal fixing agent and the heavy metal-containing ash are powdery and cannot be mixed uniformly when moisture is added. This is because the powdery heavy metal immobilizing agent and the heavy metal-containing ash are first mixed together in powder form before moisture is added, and the mixture is made uniform before being added to the kneading machine. Therefore, in a transfer means such as a transporting conveyor for transferring heavy metal-containing ash to a liquid heavy metal fixing agent, adding a powdered heavy metal fixing agent to the heavy metal-containing ash, This is preferable in that the mixing becomes good.
本発明では、上記の混練に際し、さらに水を加えてもよい。液状重金属固定化剤やキレート系重金属固定化剤に含まれる水と、別途添加される水との合量は、重金属含有灰１００重量部に対し１０〜８０重量部程度が好ましく、１５〜４０重量部程度がより好ましい。 In the present invention, water may be further added during the kneading. The total amount of water contained in the liquid heavy metal immobilizing agent or chelate heavy metal immobilizing agent and separately added water is preferably about 10 to 80 parts by weight with respect to 100 parts by weight of the heavy metal-containing ash. More preferred are parts.
本発明は、各種の重金属含有灰の処理に適用可能であるが、環境庁告示１３号試験によるｐＨが１１．５以上である重金属含有灰に対して特に有効な処理方法である。また、処理物である混練処理灰の環境庁告示１３号試験によるｐＨ（１３号ｐＨ）が８．５〜１１．５の範囲内好ましくは９．５〜１１．０の範囲内となるように、粉状重金属固定化剤と液状重金属固定化剤、更には液状のキレート系重金属固定化剤を添加することにより、硫酸バンドがｐＨ緩衝性を持つことや、リン酸が鉛を固定する能力が高いことも相まって良好に重金属の溶出を抑制することが可能である。上記１３号ｐＨが８．５よりも小さいとカドミウムが溶出しやすくなり、１１．５よりも大きいと鉛が溶出しやすくなる。 The present invention is applicable to the treatment of various heavy metal-containing ash, but is a particularly effective treatment method for heavy metal-containing ash having a pH of 11.5 or more according to the Environmental Agency Notification No. 13 test. Further, the pH (No. 13 pH) according to the Environmental Agency Notification No. 13 test of the kneaded ash which is the treated product is in the range of 8.5 to 11.5, preferably in the range of 9.5 to 11.0. By adding powdery heavy metal immobilizing agent and liquid heavy metal immobilizing agent, as well as liquid chelating heavy metal immobilizing agent, sulfuric acid band has pH buffering ability, and phosphoric acid has the ability to immobilize lead. Combined with the high value, it is possible to suppress elution of heavy metals well. If the pH of No. 13 is less than 8.5, cadmium is easily eluted, and if it is greater than 11.5, lead is easily eluted.
本発明においては、混練処理灰に水を添加して、水と混練処理灰の比（Ｌ／Ｓ）を２００以上、例えば２００〜１０００とし、１０分程度撹拌したスラリーのｐＨを測定する現場簡易測定方法によっても混練処理灰の適正なｐＨを確認することが可能である。この現場簡易測定方法での上記スラリーのｐＨ（現場簡易測定ｐＨ）が８．５〜１１．１の範囲内好ましくは９．０〜１１．０の範囲内となるように、粉状重金属固定化剤と液状重金属固定化剤、更には液状のキレート系重金属固定化剤の添加量を制御して処理することにより、重金属含有灰の性状が変化した場合も良好に重金属を固定化することができる。上記現場簡易測定ｐＨが８．５よりも小さいとカドミウムが溶出しやすくなり、１１．１よりも大きいと鉛が溶出しやすくなる。 In the present invention, water is added to the kneaded ash so that the ratio of water to the kneaded ash (L / S) is 200 or more, for example, 200 to 1000, and the pH of the slurry stirred for about 10 minutes is measured. The proper pH of the kneaded ash can be confirmed also by the measurement method. Immobilization of powdered heavy metal so that the pH of the slurry in this on-site simple measurement method (on-site simple measurement pH) is in the range of 8.5 to 11.1, preferably in the range of 9.0 to 11.0. By controlling the addition amount of the agent and the liquid heavy metal fixing agent, and also the liquid chelate heavy metal fixing agent, the heavy metal can be fixed well even when the properties of the heavy metal-containing ash change. . When the above-mentioned simple measurement pH is less than 8.5, cadmium is easily eluted, and when it is greater than 11.1, lead is easily eluted.
本発明では、このようにして得られる混練処理物を数時間〜３日程度静置し、養生させることにより、重金属固定効果を高めることができる。 In the present invention, the effect of fixing heavy metals can be enhanced by allowing the kneaded product obtained in this way to stand for several hours to 3 days and curing.
本発明においては、上記リン酸系重金属固定化剤、キレート系重金属固定化剤に加えて、更に、活性白土のような粘土鉱物重金属固定化剤、澱粉のような高分子系重金属固定化剤、セメント系重金属固定化剤、硫酸のような酸性溶液系重金属固定化剤のような他の重金属固定化剤を併用することができる。 In the present invention, in addition to the phosphate heavy metal fixing agent and chelate heavy metal fixing agent, clay mineral heavy metal fixing agent such as activated clay, polymer heavy metal fixing agent such as starch, Other heavy metal fixing agents such as cement heavy metal fixing agents and acidic solution heavy metal fixing agents such as sulfuric acid can be used in combination.
以下に実施例及び比較例を挙げて本発明をより具体的に説明するが、本発明はその要旨を超えない限り、以下の実施例により何ら限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
以下の実施例および比較例では、重金属含有灰として次の飛灰Ａ，Ｂ，Ｃについて処理を行った。
（１）都市ごみ灰溶融施設（灰溶融炉）から発生した溶融飛灰Ａ
（２）産業廃棄物焼却施設から発生した焼却飛灰Ｂ
（３）都市ごみガス化溶融施設から発生した溶融飛灰Ｃ
（４）都市ごみ灰溶融施設（灰溶融炉）から発生した溶融飛灰Ｄ
飛灰Ａ，Ｂ，Ｃ，Ｄの主要成分含有量を表１に示す。
In the following examples and comparative examples, the following fly ash A, B, and C were processed as heavy metal-containing ash.
(1) Molten fly ash A generated from municipal waste ash melting facility (ash melting furnace)
(2) Incineration fly ash B generated from industrial waste incineration facilities
(3) Molten fly ash C generated from municipal waste gasification melting facility
(4) Molten fly ash D generated from municipal waste ash melting facility (ash melting furnace)
Table 1 shows the main component contents of fly ash A, B, C, and D.
各飛灰はバグフィルタによって捕集され、サイロに一旦貯蔵された後、コンベヤによって混練機に供給した。薬剤１はサイロから混練機に向うコンベヤにて添加した。薬剤２及び薬剤３は混練機内に添加した。 Each fly ash was collected by a bag filter, temporarily stored in a silo, and then supplied to a kneader by a conveyor. Drug 1 was added on a conveyor from the silo to the kneader. Drug 2 and drug 3 were added to the kneader.
実施例１〜６、比較例１〜１３で用いた薬剤１、薬剤２、薬剤３は次の表２の通りである。 The drugs 1, 2 and 3 used in Examples 1 to 6 and Comparative Examples 1 to 13 are as shown in Table 2 below.
なお、ジチオカルバミン酸系キレート剤としては栗田工業株式会社製「アッシュナイトＳ−８０３」を用いた。これはジチオカルバミン酸ナトリウムを主成分とする。 In addition, “Ashnite S-803” manufactured by Kurita Kogyo Co., Ltd. was used as the dithiocarbamic acid chelating agent. This is based on sodium dithiocarbamate.
混練機としては、本田鐵工株式会社製の二軸同方向回転型混練成型機を用いた。混練機では、加湿のため重金属含有灰１００重量部に対し２０重量部の水を添加して混練を行った。 As the kneading machine, a biaxial co-rotating kneading molding machine manufactured by Honda Seiko Co., Ltd. was used. In the kneader, kneading was performed by adding 20 parts by weight of water to 100 parts by weight of heavy metal-containing ash for humidification.
混練物について３日間大気中で養生した後、環境庁告示第１３号法に準拠して重金属の溶出試験を行うと共に、溶出液のｐＨを測定した。結果を表３〜８に示す。 The kneaded product was cured in the atmosphere for 3 days, and then a heavy metal dissolution test was performed in accordance with the Environmental Agency Notification No. 13 and the pH of the eluate was measured. The results are shown in Tables 3-8.
表３〜８の通り、本発明によると重金属の溶出を長期にわたって十分に低くすることができる。また、本発明によると、溶出液のｐＨも全体的に適正域に制御される。 As shown in Tables 3-8, according to the present invention, the elution of heavy metals can be sufficiently reduced over a long period of time. Further, according to the present invention, the pH of the eluate is also controlled to an appropriate range as a whole.
実施例６として、飛灰Ｄに硫酸バンド３３％及び硫酸第一鉄２７％を含んだ混合粉を飛灰１００重量部に対して３、５又は７重量部添加して混合した後、正リン酸濃度３％及び硫酸バンド濃度２７％の水溶液を添加量を変えながら添加して混練し、重金属固定化剤の添加量の異なる複数の混練処理灰を得た。また、比較例１３として、飛灰Ｄに塩化第一鉄３３％水溶液を添加量を変えながら添加して混練し、添加量の異なる複数の混練処理灰を得た。 As Example 6, mixed powder containing 33% sulfuric acid band and 27% ferrous sulfate in Fly Ash D was added to 3, 5 or 7 parts by weight with respect to 100 parts by weight of Fly Ash and mixed. An aqueous solution having an acid concentration of 3% and a sulfuric acid band concentration of 27% was added and kneaded while changing the addition amount to obtain a plurality of kneaded ashes with different addition amounts of the heavy metal fixing agent. Moreover, as Comparative Example 13, a 33% ferrous chloride aqueous solution was added to fly ash D while changing the addition amount, and kneaded to obtain a plurality of kneaded ashes with different addition amounts.
実施例６と比較例１３の混練処理灰のそれぞれについて、混練処理灰１２ｇを水３Ｌとともに５Ｌの撹拌槽に投入し（Ｌ／Ｓ＝２５０）、１０分間撹拌した。撹拌後のスラリー溶液のｐＨを測定した結果（現場簡易測定ｐＨ）を横軸に、同じ混練処理灰を環境庁告示第１３号法に準拠した溶出試験を行なった際の溶出液のｐＨ測定結果（１３号ｐＨ）を縦軸にした際の相関を図１に示す。 For each of the kneaded ash of Example 6 and Comparative Example 13, 12 g of the kneaded ash was placed in a 5 L stirring tank together with 3 L of water (L / S = 250) and stirred for 10 minutes. PH measurement result of the eluate when the same kneaded ash was subjected to the dissolution test based on the Environmental Agency Notification No. 13 with the horizontal axis as the result of measuring the pH of the slurry solution after stirring (on-site simple measurement pH) The correlation when (No. 13 pH) is plotted on the vertical axis is shown in FIG.
図１の通り、実施例６では、現場簡易測定ｐＨと１３号ｐＨに強い相関があり、現場簡易測定方法により簡易に短時間で重金属固定剤の添加量が適正であるかを判定することができる。この理由は定かではないが、固体状重金属固定化剤と液体状重金属固定化剤の両方に含まれる硫酸バンドがｐＨを即時に安定させる効果があるためであると考えられる。一方、比較例１３では、現場簡易測定ｐＨと１３号ｐＨの相関は弱く、現場簡易測定方法では重金属固定剤の添加量が適正であるか否かを判定することはできないため、長時間を要する環境庁告示第１３号法に準拠した溶出試験を行う必要がある。 As shown in FIG. 1, in Example 6, there is a strong correlation between the on-site simple measurement pH and the No. 13 pH, and it is possible to easily determine whether the addition amount of the heavy metal fixing agent is appropriate in a short time by the on-site simple measurement method. it can. Although this reason is not certain, it is thought that the sulfuric acid band contained in both the solid heavy metal immobilizing agent and the liquid heavy metal immobilizing agent has an effect of immediately stabilizing the pH. On the other hand, in Comparative Example 13, the correlation between the on-site simple measurement pH and the No. 13 pH is weak, and it cannot be determined whether or not the addition amount of the heavy metal fixing agent is appropriate by the on-site simple measurement method. It is necessary to conduct a dissolution test in accordance with the Environmental Agency Notification No.13.
実施例６において、現場簡易測定ｐＨが８．５〜１１．１となるように重金属固定化剤を添加した場合には、重金属固定効果が良好であった。本発明によれば、重金属の溶出を長期にわたって十分に抑制することができるとともに、簡易かつ短時間で重金属固定化剤の添加量が適正であるかを判定して重金属固定化剤の添加量を調節することができる。 In Example 6, the heavy metal fixing effect was good when the heavy metal fixing agent was added so that the on-site simple measurement pH was 8.5 to 11.1. According to the present invention, elution of heavy metals can be sufficiently suppressed over a long period of time, and the amount of heavy metal fixing agent added can be determined simply and in a short time by determining whether the amount of heavy metal fixing agent is appropriate. Can be adjusted.
Claims (7)
該粉状重金属固定化剤が硫酸バンド、或いは硫酸バンド及び鉄系薬剤を含み、
該液状重金属固定化剤が硫酸バンド及びリン酸系重金属固定化剤を含むことを特徴とする重金属含有灰の処理方法。 A method for treating heavy metal-containing ash, which comprises adding a powdered heavy metal fixing agent, a liquid heavy metal fixing agent, and water to a heavy metal-containing ash and kneading them,
The powdery heavy metal immobilizing agent contains a sulfate band, or a sulfate band and an iron-based drug,
The method for treating heavy metal-containing ash, wherein the liquid heavy metal immobilizing agent comprises a sulfate band and a phosphoric acid heavy metal immobilizing agent.
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| CN104162533A (en) * | 2014-04-20 | 2014-11-26 | 四川大学 | Harmless processing method of wastes containing heavy metals |
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