JP2004008845A

JP2004008845A - Method of eliminating polychlorinated aromatic compound from pyrolysate polluted with polychlorinated aromatic compound

Info

Publication number: JP2004008845A
Application number: JP2002162644A
Authority: JP
Inventors: Masayuki Ono; 大野　正之; Naoshi Kaneda; 金田　尚士
Original assignee: Kansai Tech Corp
Current assignee: Kansai Tech Corp
Priority date: 2002-06-04
Filing date: 2002-06-04
Publication date: 2004-01-15
Anticipated expiration: 2022-06-04
Also published as: JP4010878B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of eliminating polychlorinated aromatic compounds from pyrolysates polluted with the polychlorinated aromatic compounds as byproducts in the process of treating a substance polluted with the polychlorinated aromatic compounds in a vacuum heating separation equipment. <P>SOLUTION: The method of eliminating polychlorinated aromatic compounds is carried out as follows. In the process of separating polychlorinated aromatic compounds from the substance polluted with polychlorinated aromatic compounds in a vacuum heating separator, wood tar in a resin state at normal temperature in the pyrolysates polluted with the byproduct polychlorinated aromatic compounds is preliminarily heated to accelerate the pyrolysis to obtain a solid substance, which is then treated in a vacuum heat treating apparatus, while a wood vinegar liquid is extracted with a hydrocarbon-based solvent. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、環境汚染物質である多塩素化芳香族化合物、たとえば多塩素化ビフェニルを含有する多塩素化ビフェニル汚染物からの多塩素化ビフェニルの除去方法及び分解処理方法に関するものである。
【０００２】
【従来の技術】
現在、多塩素化ビフェニル汚染物から多塩素化ビフェニルを除去する方法として法律上認められている方法としては、溶剤による洗浄方法及び真空加熱分離設備による分離方法がある。真空加熱分離設備により多塩素化ビフェニルに汚染された紙、木くず、等を分離する場合、分離回収した多塩素化芳香族化合物とともに、紙、木くず等の熱分解生成物が発生する。この熱分解生成物には常温で液状の一般に木酢液といわれるものと、常温で樹脂状の一般に木タールといわれるものがある。これらの熱分解生成物は高濃度の多塩素化ビフェニルに汚染された状態にある。回収した液状多塩素化ビフェニルはすでに公知の技術、たとえば、アルカリ金属ターシャリーブトキシドを用いた分解処理方法（特開平８−１０３５２号）、パラジウムカーボン触媒の存在下で水素化脱塩素反応による分解処理方法（特開平９−１９４４０１号）等で無害化処理が可能である。一方、多塩素化ビフェニルに汚染された熱分解生成物は、有機酸、フルフラール、アルコール類などからなる複雑な組成の親水性液体であり、このままでは上記の公知の技術での無害化処理は困難である。
【０００３】
【発明が解決しようとする課題】
このような状況下、多塩素化ビフェニルの処理を推進するためには、真空加熱分離設備から発生する多塩素化ビフェニルに汚染された熱分解生成物中に含まれる多塩素化ビフェニルを最終的に無害なものに処理する必要がある。
本発明は、こうした多塩素化芳香族化合物で汚染された熱分解生成物から多塩素化芳香族化合物を除去する方法を提供することを目的とするものである。
【０００４】
【課題を解決するための手段】
本発明者らは、鋭意検討した結果、真空加熱分離設備から副生する熱分解生成物（この熱分解生成物について本明細書中においては以下単に熱分解生成物ともいう）を木タールと木酢液とに分離してそれぞれについて多塩素化芳香族化合物を除去することが、特に木タールについては予備的に炭化することが効果的であることを見出すとともに、これらの熱分解生成物から除去・回収した多塩素化芳香族化合物については公知の無害化処理技術を適用して無害化が可能となることを見出し、本発明に至った。
【０００５】
すなわち、本発明は、
（１）多塩素化芳香族化合物汚染物から真空加熱分離装置で多塩素化芳香族化合物を分離する際に、副生する多塩素化芳香族化合物に汚染された熱分解生成物から多塩素化芳香族化合物を除去する方法において、前記多塩素化芳香族化合物に汚染された熱分解生成物である常温で樹脂状の木タールを常圧条件下、不活性ガス気流中で１２０℃〜４００℃に加熱し、あらかじめ熱分解を促進して予備炭化した固形物とし、次いで該固形物を真空加熱処理することを特徴とする木タールから多塩素化芳香族化合物を除去する方法。
（２）多塩素化芳香族化合物汚染物から真空加熱分離装置で多塩素化芳香族化合物を分離する際に、副生する多塩素化芳香族化合物に汚染された熱分解生成物から多塩素化芳香族化合物を除去する方法において、前記多塩素化芳香族化合物に汚染された熱分解生成物である常温で液状の木酢液を炭化水素系溶媒と混合し、多塩素化芳香族化合物を抽出することを特徴とする木酢液から多塩素化芳香族化合物を除去する方法。
（３）多塩素化芳香族化合物汚染物から真空加熱分離装置で多塩素化芳香族化合物を分離する際に、副生する多塩素化芳香族化合物に汚染された熱分解生成物から多塩素化芳香族化合物を除去する方法において、前記多塩素化芳香族化合物に汚染された熱分解生成物を常温で樹脂状の木タールと常温で液状の木酢液とに分離し、該木タールについては常圧条件下、不活性ガス気流中で１２０℃〜４００℃に加熱し、あらかじめ熱分解を促進して予備炭化した固形物とし、次いで該固形物を真空加熱処理して多塩素化芳香族化合物を除去し、又該常温で液状の木酢液については炭化水素系溶媒と混合し、多塩素化芳香族化合物を抽出することを特徴とする多塩素化芳香族化合物を除去する方法。
（４）前記（２）、（３）記載の多塩素化芳香族化合物を除去する方法において、更に抽出溶剤中に移行した多塩素化芳香族化合物を脱塩素化処理することを特徴とする多塩素化芳香族化合物を除去する方法。
（５）抽出溶剤中の多塩素化芳香族化合物の脱塩素化処理が水素化脱塩素化反応であることを特徴とする前記（４）記載の多塩素化芳香族化合物を除去する方法。
（６）抽出溶剤中の多塩素化芳香族化合物の脱塩素化処理が金属アルコラートによる脱塩素化反応であることを特徴とする前記（４）記載の多塩素化芳香族化合物を除去する方法。
（７）多塩素化芳香族化合物汚染物が多塩素化芳香族化合物を含んだ鉱油系電気絶縁油が充填されていた変圧器あるいはその解体物、多塩素化芳香族化合物が充填されていたコンデンサ、変圧器あるいはそれらの解体物である前記（１）〜（６）のいずれかに記載の多塩素化芳香族化合物を除去する方法に関する。
【０００６】
本発明において多塩素化芳香族化合物汚染物を真空加熱分離装置で処理すると回収多塩素化芳香族化合物と副生する熱分解生成物である木タールと木酢液が発生する。これらは３層混合物として得られるので、この混合物から通常の分離操作で回収多塩素化芳香族化合物と木タールと木酢液を個々に回収することができる。
本発明の多塩素化芳香族化合物の除去法の全体のシステムについてその概要を述べると、
（１）上記のように、多塩素化芳香族化合物と副生する木タールと木酢液を個々に回収する。
（２）回収した木タールは、これが系外に留出しないように常圧条件下で、不活性ガス気流中で加熱し、熱分解を進行させて予備的に炭化した固形物にする。この条件下では、系外に留出するものは液状熱分解生成物（木酢液）と回収多塩素化芳香族化合物であり、これらは前記３層混合物に戻す。
（３）木タールを予備炭化して得た固形物は通常の真空加熱分離操作により、多塩素化芳香族化合物と木酢液を分離するとともに予備炭化物は完全に炭化させて無害化される。
（４）分離回収した木酢液は、これに炭化水素系溶剤を加えて常温下攪拌混合して、木酢液に含有されている多塩素化芳香族化合物を炭化水素系溶剤により抽出する。次いで、多塩素化芳香族化合物が除去された液状熱分解生成物（木酢液）層を分離回収する。
（５）このようにして、無害化した熱分解生成物は一般の廃棄物として廃棄処理ができ、また回収した多塩素化芳香族化合物については公知の処理法を適用して脱塩素化処理することができる。
【０００７】
次に上記の操作をより具体的に述べる。
前記木タールの予備炭化処理は、凝縮装置を備えた加熱容器で不活性ガス気流中常圧条件下で１２０℃〜４００℃好ましくは２００〜２５０℃に加熱することにより行われる。この処理により、熱分解が進行し固形物とすることができる。次いでこの固形物は、公知の真空加熱分離操作によりＰＣＢ等多塩素化芳香族化合物を含まない炭化物にすることができる。すなわち、通常の廃棄物としての処分が可能となる。また、常圧条件下での熱分解であるため、木タールの系外への留出はなく、熱分解の過程で上記固形物以外の生成物は凝縮操作により回収されるが、木酢液がほとんどであり、木タールの生成はほとんど見られない。木酢液は前記３層混合物に戻すことができる。木タールが生成するとその処理のために再び固形化が必要となり、それだけ操作が煩雑になり効率を害することとなるので、好ましくない。
【０００８】
本発明において、回収した木酢液から多塩素化芳香族化合物を炭化水素系溶剤により抽出する際の好ましい温度は、常温〜１００℃であり、この温度条件下で攪拌、混合を行い、木酢液中に含まれる多塩素化芳香族化合物を炭化水素系溶剤により抽出する。次いで、抽出混合物を静置、分離する。この静置分離により炭化水素系溶剤層と木酢液層に分離することができる。
【０００９】
上記操作により、木酢液中の多塩素化芳香族化合物は、炭化水素系溶剤層に移行し、木酢液から効率的に除去されるので、必要に応じてその操作を繰り返すことにより、例えば、多塩素化芳香族化合物が多塩素化ビフェニル（ＰＣＢ）である場合には、木酢液中の多塩素化ビフェニル濃度は多塩素化ビフェニル汚染物の判定基準値以下の値となる。すなわち、本発明の処理法を行った結果、木酢液はもはや多塩素化芳香族化合物の汚染物ではなくなるので、これについては特別な処分法を要せずに通常の廃棄物としての処分が可能となる。
【００１０】
一方、抽出操作により、多塩素化芳香族化合物が移行した炭化水素溶剤は、公知の技術での無害化処理が可能である。例えば、アルカリ金属ターシャリーブトキシドを用いた分解処理方法（特開平８−１０３５２号）、パラジウムカーボン触媒の存在下での水素化脱塩素化反応による分解処理方法（特開平９−１９４４０１号）等を利用して無害化することが可能である。
【００１１】
本発明の対象となる多塩素化芳香族化合物に汚染された熱分解生成物とは、代表的には多塩素化ビフェニル変圧器（多塩素化ビフェニルを含む鉱油系電気絶縁油が充填されていた変圧器を含む）、多塩素化ビフェニルコンデンサ、多塩素化ビフェニル汚染紙くず、多塩素化ビフェニル汚染木くずを真空加熱分離設備で分離処理した際に、副生し、回収される多塩素化ビフェニルに汚染された熱分解生成物等である。この熱分解生成物には常温で液状の木酢液と樹脂状の木タールがあるが、本発明の方法は、いずれの熱分解生成物にも適用できる。
【００１２】
本発明に用いる抽出溶媒の炭化水素系溶剤は特に限定されず鎖式又は環式等の分子構造のものを広く用いることができる。本発明では鎖式炭化水素として直鎖状のものと炭素鎖に枝のある分枝状のものが含まれる。炭素数ｎは溶媒として用い得る範囲のものであればよいが、操作上ｎ＝５以上であり、上限は加温加圧下で液状となるものまで広く用いることができる。この中でｎ＝６（へキサン）以上のものが好ましく、ｎ＝１０（デカン）以上のものがより好ましく、ｎ＝１４（テトラデカン）以上のものがさらに好ましい。また、流動パラフィンのような炭化水素系混合物を用いることができる。
【００１３】
環式炭化水素としては１個の環を有する単環式炭化水素、又はこれらの鎖式炭化水素誘導体、２個以上の環を有する多環式炭化水素、縮合環式炭化水素又はこれらの鎖式炭化水素誘導体が含まれる。又、不飽和炭化水素の水素化物、例えば水素化ナフタレン、水素化インダセン、水素化フルオレン等も用いることができる。
【００１４】
抽出溶媒として用いる炭化水素の量は特に制限されるものではないが、熱分解生成物中の多塩素化芳香族化合物濃度に応じて、適切な量及び抽出回数を選定することが好ましい。又、多段向流抽出操作を行うことで抽出溶媒の使用量を低減させると共に、熱分解生成物中の残存多塩素化芳香物化合物を低減させることもできる。
【００１５】
【実施例】
以下に、本発明を実施例で説明するが、実施例は本発明の範囲を限定するものではない。
【００１６】
実施例１
オイルバス内に設置した温度計、凝縮液回収冷却器、窒素通気管を備えた５００ｍｌのステンレス製セパラブルフラスコに真空加熱装置で発生したＰＣＢ汚染樹脂状熱分解生成物（木タール）２０２．６ｇを加え、１００ｍｌ毎分の流速で窒素を通気しながら２２０℃にまで加熱した。加熱の過程で発生した低沸点成分のガスはリービッヒ冷却器（水道水）で凝縮し回収した。
【００１７】
フラスコ内の熱分解生成物は固形状に変化しており、重量は１５４．９ｇであった。凝縮回収した低沸点生成物は液状であり、重量は３５．２ｇであった。
凝縮装置を備えた鉄製容器に前記の固形状熱分解生成物（１５４．９ｇ）を入れ、４００℃、１８０〜３００Ｐａで１時間真空加熱分離操作を行った。
真空加熱分離後の容器内の熱分解生成物は完全に炭化しており、重量は７５．４ｇであった。
【００１８】
炭化物をブレンダーで粉砕した後、５３．９ｇに蒸留水５００ｍｌを加え、７時間振とう抽出した後、ろ液をｎ−ヘキサンで抽出しＥＣＤ検出器付ガスクロマトグラフ分析装置で分析した。分析の結果、抽出水中のＰＣＢ濃度は０．０００８ｍｇ／Ｌであった。
真空加熱分離操作の過程で凝縮装置に回収されたものは液状であり、重量は５６．４ｇであった。
【００１９】
実施例２
攪拌装置、温度計を備えた５００ｍｌのガラス製セパラブルフラスコにＰＣＢ汚染液状熱分解生成物（木酢液）１５０ｇ、炭化水素系抽出溶剤（沸点範囲２７７〜３９６℃、平均分子量２６４の流動パラフィン）１００ｇを加え、常温条件下で３０分攪拌を行い抽出操作を行った。抽出操作終了後、分液ロートで３０分間静置した後、上層の炭化水素系抽出溶剤と下層の木酢液を分離した。
【００２０】
前記、抽出操作後の炭化水素系抽出溶剤の１ｇを分析試料として採取し、これをｎ−ヘキサンで１０ｍｌとし、フロリジル／シリカゲル二層カラムでクリンナップした後、ＥＣＤ検出器付ガスクロマトグラフで定量分析を行った。
分析の結果、炭化水素系抽出溶剤中の多塩素化ビフェニル濃度は３．１ｍｇ／ｋｇであった。
前記、抽出操作後の木酢液１４６ｇを分析試料として採取し、ｎ−ヘキサン１００ｍｌで３回抽出を行った。
ヘキサン抽出層を無水シリカゲルカラムでクリンナップした後、フロリジル／シリカゲル二層カラム及び硫酸シリカゲルカラムでクリンナップした後、ＥＣＤ検出器付ガスクロマトグラフで定量分析を行った。
分析の結果、抽出操作後の木酢液中の多塩素化ビフェニル濃度は０．０００７ｍｇ／ｋｇであった。
【００２１】
攪拌装置、還流冷却管、温度計を備えた５００ｍｌのステンレス製セパラブル四つ口フラスコに前記、抽出操作後の炭化水素系溶剤（多塩素化ビフェニル濃度は３．１ｍｇ／ｋｇ）８０ｇ及びカリウムターシャリーブトキシド０．４ｇを加え、反応温度２５０℃にて１０分間窒素バブリングしながら攪拌下で多塩素化ビフェニルの脱塩素化反応を行った。
反応終了後次に示す手順で多塩素化ビフェニルの定量分析を行った。
反応混合物を常温にまで冷却した後、水１００ｍｌを加え分液ロートで振とう静置後、油層と水層に分離した。
【００２２】
反応後の炭化水素系抽出溶剤中の多塩素化ビフェニルを分析するために、油層から１ｇを採取し、これをｎ−ヘキサンで１０ｍｌとし、フロリジル／シリカゲル二層カラムでクリンナップした後、ＥＣＤ検出器付ガスクロマトグラフで定量分析を行った。
分析の結果、反応後の炭化水素系溶剤中の多塩素化ビフェニル濃度は０．５ｍｇ／ｋｇ以下であった。
【００２３】
【発明の効果】
以上述べた通り、本発明は環境汚染物質である多塩素化芳香族化合物で汚染された汚染物質からの同化合物の除去に有効であり、例えば多塩素化芳香族化合物に汚染された親水性の熱分解生成物から効果的に多塩素化芳香族化合物を除去することができる。特に該熱分解生成物である常温で樹脂状の木タールを特定の条件下で予備的に加熱して予め熱分解を促進して固形物とすることにより一層効率的な除去が可能となる。さらには、親水性熱分解生成物から多塩素化芳香族化合物を除去するために使用する炭化水素系抽出溶剤には多塩素化芳香族化合物が含有されているが、公知の多塩素化芳香族化合物の分解処理技術で好適に多塩素化芳香族化合物を脱塩素化処理し、無害化することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for removing polychlorinated biphenyl from a polychlorinated biphenyl contaminant containing a polychlorinated aromatic compound which is an environmental pollutant, for example, polychlorinated biphenyl, and a decomposition treatment method.
[0002]
[Prior art]
Currently, methods that are legally recognized as methods for removing polychlorinated biphenyl from polychlorinated biphenyl contaminants include a washing method using a solvent and a separation method using a vacuum heating separation facility. When paper, wood chips, etc. contaminated with polychlorinated biphenyls are separated by vacuum heating separation equipment, thermal decomposition products such as paper, wood chips, etc. are generated together with the separated and recovered polychlorinated aromatic compounds. The pyrolysis products include those which are generally called wood vinegar liquid at room temperature and those which are generally resinous at room temperature and called wood tar. These pyrolysis products are contaminated with high concentrations of polychlorinated biphenyl. The recovered liquid polychlorinated biphenyl can be decomposed by a known technique, for example, a decomposition method using an alkali metal tertiary butoxide (JP-A-8-10352), a hydrodechlorination reaction in the presence of a palladium carbon catalyst. Detoxification treatment can be performed by a method (Japanese Patent Laid-Open No. 9-194401) or the like. On the other hand, the pyrolysis product contaminated with polychlorinated biphenyl is a hydrophilic liquid having a complicated composition composed of organic acids, furfural, alcohols, and the like, and it is difficult to make the detoxification treatment by the above-described known technique as it is. It is.
[0003]
[Problems to be solved by the invention]
Under such circumstances, in order to promote the treatment of polychlorinated biphenyl, the polychlorinated biphenyl contained in the pyrolysis product contaminated with polychlorinated biphenyl generated from the vacuum heating separation equipment is finally It needs to be treated to something harmless.
An object of the present invention is to provide a method for removing a polychlorinated aromatic compound from a pyrolysis product contaminated with such a polychlorinated aromatic compound.
[0004]
[Means for Solving the Problems]
The present inventors have conducted intensive studies and as a result, have found that pyrolysis products by-produced from the vacuum heating separation equipment (hereinafter, these pyrolysis products are also simply referred to as pyrolysis products in the present specification) are wood tar and wood vinegar. It has been found that it is effective to separate polychlorinated aromatic compounds by separating them into liquids, and it is especially effective to preliminarily carbonize wood tar. It has been found that the recovered polychlorinated aromatic compounds can be rendered harmless by applying a known detoxification treatment technique, and the present invention has been accomplished.
[0005]
That is, the present invention
(1) When a polychlorinated aromatic compound is separated from a polychlorinated aromatic compound contaminant by a vacuum heating separation apparatus, polychlorination is performed from a pyrolysis product contaminated by the by-product polychlorinated aromatic compound. In the method for removing an aromatic compound, a resinous wood tar which is a pyrolysis product contaminated by the polychlorinated aromatic compound at normal temperature is subjected to a normal pressure condition under an inert gas stream at 120 ° C to 400 ° C. A method for removing polychlorinated aromatic compounds from wood tar, wherein the solid is heated in advance to promote thermal decomposition to obtain a pre-carbonized solid, and then the solid is subjected to a vacuum heat treatment.
(2) When a polychlorinated aromatic compound is separated from a polychlorinated aromatic compound contaminant by a vacuum heating separation device, polychlorination is performed from a pyrolysis product contaminated by the by-product polychlorinated aromatic compound. In the method for removing an aromatic compound, a woody vinegar liquid which is liquid at room temperature, which is a pyrolysis product contaminated with the polychlorinated aromatic compound, is mixed with a hydrocarbon solvent to extract the polychlorinated aromatic compound. A method for removing a polychlorinated aromatic compound from a wood vinegar solution, comprising:
(3) When a polychlorinated aromatic compound is separated from a polychlorinated aromatic compound contaminant by a vacuum heating separation device, polychlorination is performed from a pyrolysis product contaminated by the by-product polychlorinated aromatic compound. In the method for removing an aromatic compound, a pyrolysis product contaminated with the polychlorinated aromatic compound is separated into a resinous wood tar at room temperature and a liquid wood vinegar at room temperature, and the wood tar is constantly separated. Under pressure conditions, the mixture is heated to 120 ° C. to 400 ° C. in an inert gas stream to promote thermal decomposition in advance to obtain a pre-carbonized solid, and then the solid is subjected to vacuum heat treatment to convert the polychlorinated aromatic compound. A method for removing polychlorinated aromatic compounds, comprising removing the wood vinegar liquid at room temperature with a hydrocarbon solvent to extract the polychlorinated aromatic compounds.
(4) The method for removing a polychlorinated aromatic compound according to the above (2) or (3), wherein the polychlorinated aromatic compound transferred into the extraction solvent is further dechlorinated. A method for removing chlorinated aromatic compounds.
(5) The method for removing a polychlorinated aromatic compound according to the above (4), wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a hydrodechlorination reaction.
(6) The method for removing a polychlorinated aromatic compound according to the above (4), wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a dechlorination reaction with a metal alcoholate.
(7) Transformers or disassembled transformers filled with mineral oil-based electric insulating oil containing polychlorinated aromatic compounds containing polychlorinated aromatic compounds, and capacitors packed with polychlorinated aromatic compounds And a method for removing a polychlorinated aromatic compound according to any one of the above (1) to (6), which is a transformer or a disassembled product thereof.
[0006]
In the present invention, when the polychlorinated aromatic compound contaminant is treated by the vacuum heating separation device, wood tar and wood vinegar, which are the by-products of thermal decomposition produced as a recovered polychlorinated aromatic compound, are generated. Since these are obtained as a three-layer mixture, the recovered polychlorinated aromatic compound, wood tar and wood vinegar can be individually recovered from the mixture by a usual separation operation.
An overview of the overall system of the method for removing polychlorinated aromatic compounds of the present invention is given below.
(1) As described above, the polychlorinated aromatic compound, wood tar and by-product vinegar are separately collected.
(2) The collected wood tar is heated in an inert gas stream under normal pressure conditions so that it does not distill out of the system, and is thermally decomposed to be a preliminarily carbonized solid. Under these conditions, what distills out of the system are liquid pyrolysis products (wood vinegar) and recovered polychlorinated aromatic compounds, which are returned to the three-layer mixture.
(3) The solids obtained by pre-carbonizing the wood tar are separated into polychlorinated aromatic compounds and wood vinegar by a usual vacuum heating separation operation, and the pre-carbonized material is completely carbonized to be harmless.
(4) The wood vinegar separated and recovered is mixed with a hydrocarbon solvent at room temperature and stirred and mixed, and the polychlorinated aromatic compound contained in the wood vinegar is extracted with the hydrocarbon solvent. Next, a liquid pyrolysis product (wood vinegar) layer from which the polychlorinated aromatic compound has been removed is separated and recovered.
(5) The detoxified thermal decomposition product can be disposed of as general waste, and the recovered polychlorinated aromatic compound is dechlorinated by applying a known treatment method. be able to.
[0007]
Next, the above operation will be described more specifically.
The pre-carbonization treatment of the wood tar is performed by heating in a heating vessel equipped with a condensing device in an inert gas stream at normal pressure under a condition of 120 ° C. to 400 ° C., preferably 200 ° C. to 250 ° C. By this treatment, thermal decomposition proceeds and a solid can be obtained. Next, this solid can be converted into a carbide free of polychlorinated aromatic compounds such as PCB by a known vacuum heating separation operation. That is, it can be disposed of as ordinary waste. In addition, since the thermal decomposition is carried out under normal pressure conditions, there is no distillation of wood tar out of the system, and the products other than the solids are recovered by a condensation operation in the process of thermal decomposition, but the wood vinegar is Mostly, there is almost no production of wood tar. The wood vinegar can be returned to the three-layer mixture. When wood tar is produced, solidification is required again for the treatment, which makes the operation complicated and impairs efficiency, which is not preferable.
[0008]
In the present invention, the preferred temperature for extracting the polychlorinated aromatic compound from the collected wood vinegar with a hydrocarbon solvent is from room temperature to 100 ° C., and stirring and mixing are performed under these temperature conditions. Is extracted with a hydrocarbon solvent. Then, the extraction mixture is left to stand and separated. This stationary separation allows separation into a hydrocarbon solvent layer and a wood vinegar liquid layer.
[0009]
By the above-mentioned operation, the polychlorinated aromatic compound in the wood vinegar moves to the hydrocarbon-based solvent layer and is efficiently removed from the wood vinegar. Therefore, by repeating the operation as needed, for example, When the chlorinated aromatic compound is polychlorinated biphenyl (PCB), the concentration of polychlorinated biphenyl in the wood vinegar is a value equal to or less than the determination reference value for polychlorinated biphenyl contaminants. That is, as a result of performing the treatment method of the present invention, the wood vinegar solution is no longer a contaminant of the polychlorinated aromatic compound, and thus can be disposed of as ordinary waste without a special disposal method. It becomes.
[0010]
On the other hand, the hydrocarbon solvent to which the polychlorinated aromatic compound has been transferred by the extraction operation can be detoxified by a known technique. For example, a decomposition treatment method using an alkali metal tertiary butoxide (JP-A-8-10352), a decomposition treatment method by a hydrodechlorination reaction in the presence of a palladium carbon catalyst (JP-A-9-194401), and the like are described. It can be used to make it harmless.
[0011]
The pyrolysis product contaminated with the polychlorinated aromatic compound which is the object of the present invention is typically a polychlorinated biphenyl transformer (mineral oil-based electrical insulating oil containing polychlorinated biphenyl was filled. Transformers), polychlorinated biphenyl capacitors, polychlorinated biphenyl-contaminated paper waste, and polychlorinated biphenyl-contaminated wood waste when separated by vacuum heating and separation equipment. Thermal decomposition products. The pyrolysis products include wood vinegar liquid and resinous wood tar at room temperature, and the method of the present invention can be applied to any pyrolysis products.
[0012]
The hydrocarbon solvent of the extraction solvent used in the present invention is not particularly limited, and those having a molecular structure such as a chain type or a cyclic type can be widely used. In the present invention, the chain hydrocarbon includes a straight chain hydrocarbon and a branched hydrocarbon having a branch in the carbon chain. The number of carbon atoms n may be in a range that can be used as a solvent, but n is 5 or more in terms of operation, and the upper limit can be widely used as long as it becomes a liquid under heating and pressure. Among them, those having n = 6 (hexane) or more are preferable, those having n = 10 (decane) or more are more preferable, and those having n = 14 (tetradecane) are more preferable. Further, a hydrocarbon-based mixture such as liquid paraffin can be used.
[0013]
As the cyclic hydrocarbon, a monocyclic hydrocarbon having one ring, or a chain hydrocarbon derivative thereof, a polycyclic hydrocarbon having two or more rings, a condensed hydrocarbon or a chain hydrocarbon thereof Includes hydrocarbon derivatives. Also, hydrides of unsaturated hydrocarbons, for example, naphthalene hydride, indacene hydride, fluorene hydride and the like can be used.
[0014]
The amount of the hydrocarbon used as the extraction solvent is not particularly limited, but it is preferable to select an appropriate amount and the number of extractions according to the concentration of the polychlorinated aromatic compound in the pyrolysis product. Further, by performing the multi-stage countercurrent extraction operation, the amount of the extraction solvent used can be reduced, and the residual polychlorinated aromatic compound in the pyrolysis product can also be reduced.
[0015]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the examples do not limit the scope of the present invention.
[0016]
Example 1
202.6 g of PCB-contaminated resinous pyrolysis products (wood tar) generated by a vacuum heating device in a 500 ml stainless steel separable flask equipped with a thermometer, a condensate recovery cooler, and a nitrogen vent tube installed in an oil bath. And heated to 220 ° C. while bubbling nitrogen through at a flow rate of 100 ml per minute. The low-boiling component gas generated during the heating process was condensed and recovered in a Liebig condenser (tap water).
[0017]
The pyrolysis product in the flask changed to a solid state, and weighed 154.9 g. The low-boiling product condensed and recovered was liquid and weighed 35.2 g.
The solid pyrolysis product (154.9 g) was placed in an iron container equipped with a condenser, and subjected to vacuum heating separation at 400 ° C. and 180 to 300 Pa for 1 hour.
The thermally decomposed product in the container after the vacuum heating separation was completely carbonized and weighed 75.4 g.
[0018]
After pulverizing the carbide with a blender, 500 ml of distilled water was added to 53.9 g, and the mixture was extracted with shaking for 7 hours. The filtrate was extracted with n-hexane and analyzed with a gas chromatograph equipped with an ECD detector. As a result of the analysis, the PCB concentration in the extraction water was 0.0008 mg / L.
What was collected in the condenser during the vacuum heating separation operation was liquid and weighed 56.4 g.
[0019]
Example 2
In a 500 ml glass separable flask equipped with a stirrer and a thermometer, 150 g of a PCB-contaminated liquid pyrolysis product (wood vinegar) and 100 g of a hydrocarbon-based extraction solvent (liquid paraffin having a boiling point range of 277 to 396 ° C. and an average molecular weight of 264). , And the mixture was stirred for 30 minutes at room temperature to perform an extraction operation. After the completion of the extraction operation, the mixture was allowed to stand for 30 minutes using a separating funnel, and then the hydrocarbon-based extraction solvent in the upper layer and the wood vinegar in the lower layer were separated.
[0020]
1 g of the above-mentioned hydrocarbon-based extraction solvent after the extraction operation was collected as an analytical sample, made up to 10 ml with n-hexane, cleaned up with a florisil / silica gel two-layer column, and subjected to quantitative analysis with a gas chromatograph equipped with an ECD detector. went.
As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 3.1 mg / kg.
146 g of the above-mentioned wood vinegar solution after the extraction operation was collected as an analysis sample, and extracted three times with 100 ml of n-hexane.
After the hexane extract layer was cleaned up with an anhydrous silica gel column, it was cleaned up with a florisil / silica gel two-layer column and a sulfuric acid silica gel column, and quantitative analysis was performed with a gas chromatograph equipped with an ECD detector.
As a result of the analysis, the concentration of polychlorinated biphenyl in the wood vinegar solution after the extraction operation was 0.0007 mg / kg.
[0021]
In a 500 ml stainless steel separable four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 80 g of the hydrocarbon-based solvent (polychlorinated biphenyl concentration is 3.1 mg / kg) and potassium tertiary after the extraction operation. Butoxide was added in an amount of 0.4 g, and a dechlorination reaction of polychlorinated biphenyl was performed with stirring at a reaction temperature of 250 ° C. for 10 minutes while bubbling with nitrogen.
After the reaction was completed, quantitative analysis of polychlorinated biphenyl was performed by the following procedure.
After the reaction mixture was cooled to room temperature, 100 ml of water was added, and the mixture was left to shake with a separating funnel and then separated into an oil layer and an aqueous layer.
[0022]
In order to analyze polychlorinated biphenyl in the hydrocarbon-based extraction solvent after the reaction, 1 g was collected from the oil layer, made up to 10 ml with n-hexane, and cleaned up with a Florisil / silica gel two-layer column, and then subjected to an ECD detector. Quantitative analysis was performed with a gas chromatograph attached.
As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon solvent after the reaction was 0.5 mg / kg or less.
[0023]
【The invention's effect】
As described above, the present invention is effective for the removal of pollutants contaminated with polychlorinated aromatic compounds, which are environmental pollutants. The polychlorinated aromatic compound can be effectively removed from the pyrolysis product. In particular, the resinous wood tar, which is a thermal decomposition product, is preliminarily heated under a specific condition at room temperature to promote thermal decomposition in advance to make it a solid, thereby enabling more efficient removal. Furthermore, the hydrocarbon-based extraction solvent used for removing the polychlorinated aromatic compound from the hydrophilic pyrolysis product contains the polychlorinated aromatic compound, but the known polychlorinated aromatic compound is used. A polychlorinated aromatic compound can be suitably dechlorinated and rendered harmless by a compound decomposition technique.

Claims

When polychlorinated aromatic compounds are separated from polychlorinated aromatic compounds by vacuum heating separation equipment, polychlorinated aromatic compounds are condensed from pyrolysis products contaminated by by-product polychlorinated aromatic compounds. In a method of removing, the resinous wood tar at room temperature, which is a pyrolysis product contaminated with the polychlorinated aromatic compound, is heated to 120 ° C. to 400 ° C. in an inert gas stream under normal pressure conditions. A method for removing polychlorinated aromatic compounds from wood tar, which comprises preliminarily promoting pyrolysis to obtain a pre-carbonized solid, and then subjecting the solid to a vacuum heat treatment.

When polychlorinated aromatic compounds are separated from polychlorinated aromatic compounds by vacuum heating separation equipment, polychlorinated aromatic compounds are condensed from pyrolysis products contaminated by by-product polychlorinated aromatic compounds. In the method for removing a polychlorinated aromatic compound, a liquid wood vinegar liquid at room temperature, which is a thermal decomposition product contaminated with the polychlorinated aromatic compound, is mixed with a hydrocarbon solvent to extract the polychlorinated aromatic compound. A method for removing polychlorinated aromatic compounds from wood vinegar.

When polychlorinated aromatic compounds are separated from polychlorinated aromatic compounds by vacuum heating separation equipment, polychlorinated aromatic compounds are condensed from pyrolysis products contaminated by by-product polychlorinated aromatic compounds. In the method of removing, the pyrolysis product contaminated with the polychlorinated aromatic compound is separated into a resinous wood tar at room temperature and a liquid wood vinegar liquid at room temperature, and the wood tar is subjected to normal pressure conditions. Heated to 120 ° C. to 400 ° C. in a stream of inert gas to promote thermal decomposition in advance to obtain a pre-carbonized solid, and then subject the solid to vacuum heating to remove polychlorinated aromatic compounds; A method for removing polychlorinated aromatic compounds, comprising mixing the wood vinegar liquid at room temperature with a hydrocarbon solvent to extract the polychlorinated aromatic compounds.

The method for removing a polychlorinated aromatic compound according to claim 2 or 3, further comprising the step of dechlorinating the polychlorinated aromatic compound transferred into the extraction solvent. How to remove.

The method for removing a polychlorinated aromatic compound according to claim 4, wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a hydrodechlorination reaction.

The method for removing a polychlorinated aromatic compound according to claim 4, wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a dechlorination reaction with a metal alcoholate.

Transformers or disassembled transformers filled with mineral oil-based electrical insulating oil containing polychlorinated aromatic compounds containing polychlorinated aromatic compounds, capacitors and transformers filled with polychlorinated aromatic compounds Alternatively, the method for removing a polychlorinated aromatic compound according to any one of claims 1 to 6, which is a disassembled product thereof.