JP2004115639A - Heavy metal fixing agent and low-temperature stabilization method of heavy metal fixing agent - Google Patents
Heavy metal fixing agent and low-temperature stabilization method of heavy metal fixing agent Download PDFInfo
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- JP2004115639A JP2004115639A JP2002280412A JP2002280412A JP2004115639A JP 2004115639 A JP2004115639 A JP 2004115639A JP 2002280412 A JP2002280412 A JP 2002280412A JP 2002280412 A JP2002280412 A JP 2002280412A JP 2004115639 A JP2004115639 A JP 2004115639A
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- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 107
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000006641 stabilisation Effects 0.000 title claims abstract description 10
- 238000011105 stabilization Methods 0.000 title claims abstract description 10
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims abstract description 162
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 87
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 83
- 239000007864 aqueous solution Substances 0.000 claims abstract description 55
- 229920000768 polyamine Polymers 0.000 claims abstract description 23
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 claims description 81
- 230000008014 freezing Effects 0.000 claims description 22
- 238000007710 freezing Methods 0.000 claims description 22
- 229910000000 metal hydroxide Inorganic materials 0.000 claims description 8
- 150000004692 metal hydroxides Chemical class 0.000 claims description 8
- 230000000087 stabilizing effect Effects 0.000 claims description 5
- QGJOPFRUJISHPQ-NJFSPNSNSA-N carbon disulfide-14c Chemical compound S=[14C]=S QGJOPFRUJISHPQ-NJFSPNSNSA-N 0.000 claims description 2
- 230000001112 coagulating effect Effects 0.000 claims description 2
- 239000002253 acid Substances 0.000 abstract description 6
- 239000000243 solution Substances 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 abstract description 4
- 230000015271 coagulation Effects 0.000 abstract description 2
- 238000005345 coagulation Methods 0.000 abstract description 2
- 229960005141 piperazine Drugs 0.000 description 66
- 239000010881 fly ash Substances 0.000 description 16
- 239000002956 ash Substances 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 10
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 9
- -1 etc. Substances 0.000 description 8
- JRRBJSPQEVZLPI-UHFFFAOYSA-N piperazin-1-ium;hydroxide Chemical compound O.C1CNCCN1 JRRBJSPQEVZLPI-UHFFFAOYSA-N 0.000 description 7
- 229960003641 piperazine hydrate Drugs 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 150000001412 amines Chemical class 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 4
- 239000002689 soil Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- FAGUFWYHJQFNRV-UHFFFAOYSA-N tetraethylenepentamine Chemical compound NCCNCCNCCNCCN FAGUFWYHJQFNRV-UHFFFAOYSA-N 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 229910052783 alkali metal Inorganic materials 0.000 description 3
- 150000001340 alkali metals Chemical class 0.000 description 3
- 125000003277 amino group Chemical group 0.000 description 3
- 239000002440 industrial waste Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 239000003002 pH adjusting agent Substances 0.000 description 3
- XMNPUFGPSRCSQJ-UHFFFAOYSA-N piperazine;potassium Chemical compound [K].C1CNCCN1 XMNPUFGPSRCSQJ-UHFFFAOYSA-N 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 150000004697 chelate complex Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
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- 239000007789 gas Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
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- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- JBFDWEHJDUALEL-UHFFFAOYSA-N piperazine-1,2-dicarbodithioic acid Chemical class SC(=S)C1CNCCN1C(S)=S JBFDWEHJDUALEL-UHFFFAOYSA-N 0.000 description 2
- 125000000467 secondary amino group Chemical group [H]N([*:1])[*:2] 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
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- 239000002351 wastewater Substances 0.000 description 2
- VILCJCGEZXAXTO-UHFFFAOYSA-N 2,2,2-tetramine Chemical compound NCCNCCNCCN VILCJCGEZXAXTO-UHFFFAOYSA-N 0.000 description 1
- RXFCIXRFAJRBSG-UHFFFAOYSA-N 3,2,3-tetramine Chemical compound NCCCNCCNCCCN RXFCIXRFAJRBSG-UHFFFAOYSA-N 0.000 description 1
- XYUINKARGUCCQJ-UHFFFAOYSA-N 3-imino-n-propylpropan-1-amine Chemical compound CCCNCCC=N XYUINKARGUCCQJ-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 1
- BWGNESOTFCXPMA-UHFFFAOYSA-N Dihydrogen disulfide Chemical compound SS BWGNESOTFCXPMA-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- CJKRXEBLWJVYJD-UHFFFAOYSA-N N,N'-diethylethylenediamine Chemical compound CCNCCNCC CJKRXEBLWJVYJD-UHFFFAOYSA-N 0.000 description 1
- 229920002873 Polyethylenimine Polymers 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 125000002723 alicyclic group Chemical group 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 150000004985 diamines Chemical group 0.000 description 1
- NLZXQOOZQAGNCY-UHFFFAOYSA-L dipotassium;piperazine-1,4-dicarbodithioate Chemical compound [K+].[K+].[S-]C(=S)N1CCN(C([S-])=S)CC1 NLZXQOOZQAGNCY-UHFFFAOYSA-L 0.000 description 1
- 239000012717 electrostatic precipitator Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- DTSDBGVDESRKKD-UHFFFAOYSA-N n'-(2-aminoethyl)propane-1,3-diamine Chemical compound NCCCNCCN DTSDBGVDESRKKD-UHFFFAOYSA-N 0.000 description 1
- LSHROXHEILXKHM-UHFFFAOYSA-N n'-[2-[2-[2-(2-aminoethylamino)ethylamino]ethylamino]ethyl]ethane-1,2-diamine Chemical compound NCCNCCNCCNCCNCCN LSHROXHEILXKHM-UHFFFAOYSA-N 0.000 description 1
- DFPGBRPWDZFIPP-UHFFFAOYSA-N n'-butylethane-1,2-diamine Chemical compound CCCCNCCN DFPGBRPWDZFIPP-UHFFFAOYSA-N 0.000 description 1
- SCZVXVGZMZRGRU-UHFFFAOYSA-N n'-ethylethane-1,2-diamine Chemical compound CCNCCN SCZVXVGZMZRGRU-UHFFFAOYSA-N 0.000 description 1
- KFIGICHILYTCJF-UHFFFAOYSA-N n'-methylethane-1,2-diamine Chemical compound CNCCN KFIGICHILYTCJF-UHFFFAOYSA-N 0.000 description 1
- QHJABUZHRJTCAR-UHFFFAOYSA-N n'-methylpropane-1,3-diamine Chemical compound CNCCCN QHJABUZHRJTCAR-UHFFFAOYSA-N 0.000 description 1
- KVKFRMCSXWQSNT-UHFFFAOYSA-N n,n'-dimethylethane-1,2-diamine Chemical compound CNCCNC KVKFRMCSXWQSNT-UHFFFAOYSA-N 0.000 description 1
- UQUPIHHYKUEXQD-UHFFFAOYSA-N n,n′-dimethyl-1,3-propanediamine Chemical compound CNCCCNC UQUPIHHYKUEXQD-UHFFFAOYSA-N 0.000 description 1
- BXYVQNNEFZOBOZ-UHFFFAOYSA-N n-[3-(dimethylamino)propyl]-n',n'-dimethylpropane-1,3-diamine Chemical compound CN(C)CCCNCCCN(C)C BXYVQNNEFZOBOZ-UHFFFAOYSA-N 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
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- 239000003960 organic solvent Substances 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
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- 125000001302 tertiary amino group Chemical group 0.000 description 1
- AGGKEGLBGGJEBZ-UHFFFAOYSA-N tetramethylenedisulfotetramine Chemical compound C1N(S2(=O)=O)CN3S(=O)(=O)N1CN2C3 AGGKEGLBGGJEBZ-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、工場排水や、産業廃棄物、都市ゴミの焼却プラントにおいて発生する焼却灰や、焼却プラント等から排ガスと共に排出されバグフィルター等で補集された飛灰、溶融炉から排ガスと共に排出されバグフィルター等で補集された溶融飛灰、重金属汚染土壌等に含まれる重金属を固定し、環境への重金属汚染を防止する重金属固定剤に関し、特に、寒冷地においても重金属を含有する飛灰等の処理を効率よく行うことができる重金属固定剤及びその低温安定化方法に関する。
【０００２】
【従来の技術】
工場排水や、都市ゴミや産業廃棄物等の焼却プラントから排出される焼却灰や、排煙中からバグフィルター等で補集された飛灰及び溶融飛灰や、重金属汚染土壌等を処理するに際し、焼却灰や、飛灰及び溶融飛灰等に含有される鉛、水銀、クロム、カドミウム等の有害金属の環境への放出を阻止するため、焼却灰、飛灰、溶融飛灰等をセメント固化する方法や、焼却灰、飛灰、溶融飛灰等を酸で処理し重金属を抽出する方法があったが、廃棄物の体積の増加や、酸により抽出した重金属の処理の問題があった。このため、特殊な装置を必要とせず、後処理が不要である重金属固定剤による処理が採用されていた。重金属固定剤として、ジチオカルボキシル基を官能基として有するアミン誘導体の液体キレート剤は、重金属の捕集効果も高く、雨水等に不溶出化することができるため多く用いられており、中でも特にピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液が、好適に用いられることが知られている。（特許文献１を参照）
【０００３】
また、ジチオカルボキシル基を有する化合物を主成分とする重金属固定剤で重金属含有飛灰を処理するにあたり、その重金属固定剤にその主成分の０．１〜１００モル％のアミンを含有させることを特徴とする重金属固定剤の安定化方法が知られている。（特許文献２を参照）
【０００４】
また、このような重金属固定剤として使用されるピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液は、窒素雰囲気下、ピペラジンと水酸化ナトリウム、水酸化カリウム等のアルカリ水溶液を混合し、３０〜４０℃の範囲で攪拌しながら二硫化炭素を滴下して反応させることにより、高濃度のピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩が含有される水溶液として製造されていた。
【０００５】
【特許文献１】
特開平８−２２４５６０号公報
【特許文献２】
特開平９−１１１０号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、上記の方法で製造されたピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液からなる重金属固定剤は、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩が高濃度、例えば、３５重量％以上となると、凝固点が上昇し、低温の寒冷地等で使用する場合には、水溶液自体が凝固してしまうため、保管、貯蔵に特別な装置が必要となり、これを用いた作業にも制約がかかり、コストが高くなるのみならず、煩雑な操作を要する等の問題があり、取り扱いが非常に困難であった。
【０００７】
本発明は、凝固点を降下させ、寒冷地においても凝固せず安定な状態を保持できる低温安定性を有する重金属固定剤及び寒冷地においても飛灰等の処理を容易とする重金属固定剤の低温安定化方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明者らは、上記課題を解決するために鋭意検討した結果、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液からなる重金属固定剤に、所定量のピペラジン又はポリアミンを含有させることにより、低温において凝固しない重金属固定剤を得ることができ、重金属固定剤の安定化をすることができることを見出し、本発明を完成するに至った。
【０００９】
即ち、本発明は、
（１）ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液を主成分とする重金属固定剤において、ピペラジンを主成分に対して０．０１〜２．５重量％含有し、低温で凝固しないことを特徴とする重金属固定剤に関し、
（２）ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液を主成分とする重金属固定剤において、ポリアミンを主成分に対して０．０１〜４．５重量％含有し、低温で凝固しないことを特徴とする重金属固定剤に関し、
（３）ピペラジン、金属水酸化物、二硫化炭素より製造されるピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液を主成分とする重金属固定剤において、用いる二硫化炭素から算出される理論量より０．０１〜２４重量％過剰のピペラジンを、金属水酸化物、二硫化炭素と反応させて製造した水溶液を主成分とし、低温で凝固しないことを特徴とする重金属固定剤に関し、
（４）低温が、ピペラジンまたはポリアミンを添加しない状態での凝固点よりも低い温度であることを特徴とする（１）〜（３）のいずれかに記載の重金属固定剤、
（５）ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を３５重量％以上含有することを特徴とする（１）〜（４）のいずれかに記載の重金属固定剤に関する。
【００１０】
さらに、
（６）ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液を主成分とする重金属固定剤に、ピペラジンを主成分に対して０．０１〜２．５重量％を添加することを特徴とする重金属固定剤の低温安定化方法に関し、
（７）ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液を主成分とする重金属固定剤に、ポリアミンを主成分に対して０．０１〜４．５重量％を添加することを特徴とする重金属固定剤の低温安定化方法に関し、
（８）用いる二硫化炭素から算出される理論量より０．０１〜２４重量％過剰のピペラジンと金属水酸化物、二硫化炭素とを反応させて製造した水溶液を主成分として用いることを特徴とする重金属固定剤の低温安定化方法に関し、
（９）低温が、ピペラジンまたはポリアミンを添加しない状態での凝固点よりも低い温度であることを特徴とする（６）〜（８）のいずれかに記載の重金属固定剤の低温安定化方法、
（１０）ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を３５重量％以上含有する重金属固定剤を用いることを特徴とする（６）〜（９）のいずれかに記載の重金属固定剤の低温安定化方法に関する。
【００１１】
【発明の実施の形態】
本発明の重金属固定剤に使用されるピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩としては、重金属を含有する飛灰等と混合されることにより、塩部分が重金属原子と置換して重金属原子とのキレート錯体を容易に形成し、重金属原子の固定を迅速に、且つ、強固に行ない、固定された重金属原子は雨水等により放出されないものであれば、特に制限されないが、具体的には、ピペラジンビスカルボジチオ酸と、カリウム、ナトリウム、リチウム等のアルカリ金属等との塩を好ましく例示することができる。
【００１２】
本発明の重金属固定剤の主成分であるピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液として、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を製造単離し、さらに水溶液に調製して用いることもできるが、ピペラジン、アルカリ金属水酸化物及び二硫化炭素を水溶液中で混合して得られる水溶液を、必要に応じて過剰の二硫化炭素を除去する操作、ｐＨ調製操作等を行い、そのまま用いることもできる。また、主成分となる水溶液には、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩以外に、例えば、ピペラジンジ−Ｎ，−モノカルボジチオ酸塩等の化合物を含んでいてもよい。
【００１３】
本発明に使用されるピペラジンは、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液に溶解されて使用されるものであり、ピペラジン無水物又はピペラジン水和物のいずれも適用することができる。ピペラジン無水物又はピペラジン水和物は固体状態のまま、あるいは水溶液として重金属固定剤に添加されて用いられてもよく、また、融点が低いピペラジン水和物は溶融して液状として重金属固定剤に添加されて用いられてもよい。これらのピペラジンの水溶液は塩基性であり、重金属固定剤の凝固点を下降させると共に、二硫化炭素の発生を抑制する作用を有する。
【００１４】
ピペラジンの含有量は、主成分となる水溶液に対して、０．０１〜２．５重量％の範囲が好ましい。０．０１重量％以下では、凝固点を下げるという低温での安定性にほとんど寄与せず、２．５重量％以上では、逆に凝固点が上昇し、低温での安定性が悪くなる。尚、低温とは、使用時、または保存時において、ピペラジン、またはポリアミンを添加しない状態での凝固点よりも低い温度を意味し、添加する時期は、反応前、反応後は問わない。例えば、３５重量％濃度のピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩の場合、−１０℃以下においても、安定して保存、使用が可能となる。以下本明細書において、低温とは、同様の意義に用いることとする。
【００１５】
本発明に使用されるポリアミンは、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液に溶解されて使用されるものであり、ピペラジンと同様に、水に易溶であり、その水溶液は塩基性であり、重金属固定剤の凝固点を下降させると共に、二硫化炭素の発生を抑制する作用を有する。ポリアミンは、複数のアミノ基を有するものであれば、特に限定されるものではなく、アミノ基としては、第一級アミノ基、第二級アミノ基、第三級アミノ基のいずれであってもよく、また、ポリアミンとしては、ジアミン、トリアミン、テトラミン等複数のアミノ基を有するものを挙げることができるが、脂肪族アミンが好ましく、脂肪族アミンであれば、脂肪族不飽和アミン、脂環式アミン等も適用することができる。
【００１６】
上記ポリアミンとしては、第二級アミノ基を分子内に少なくとも一つもった多価アミンが好適であり、具体的には、Ｎ−メチルエチレンジアミン、Ｎ−エチルエチレンジアミン、Ｎ−ブチルエチレンジアミン、Ｎ，Ｎ´−ジメチルエチレンジアミン、Ｎ，Ｎ´−ジエチルエチレンジアミン、Ｎ−メチル−１，３−プロパンジアミン、Ｎ，Ｎ´−ジメチル−１，３−プロパンジアミン、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン、イミノビスプロピルアミン、ポリエチレンイミン、Ｎ−（２−アミノエチル）−１，３−プロパンジアミン、Ｎ，Ｎ´−ビス（３−アミノプロピル）エチレンジアミン、３，３´−イミノビス（Ｎ，Ｎ´−ジメチルプロピルアミン）、２，２´−イソノジエタノール等を例示することができる。
【００１７】
ポリアミンの含有量は、主成分となる水溶液に対して、０．０１〜４．５重量％の範囲が好ましい。０．０１重量％以下では、凝固点を下げるという低温での安定性にほとんど寄与せず、４．５重量％以上では、逆に凝固点が上昇し、低温での安定性が悪くなる。
【００１８】
本発明の重金属固定剤には、これらのポリアミンやピペラジンに加え、水溶液を塩基性に保持するためのｐＨ調整剤を含有させることができる。ｐＨ調整剤が含有されたものは、保存期間中の水素イオン濃度を所定の範囲に保持し、副反応生成物であるチオ炭酸塩等から生じる二硫化炭素の発生を防止することができる。水溶液の水素イオン濃度がｐＨ１０以上であれば、空気中の二酸化炭素等が混入することにより水溶液が酸性になっても、また、高温に晒された場合でも、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩が分解され二硫化炭素が発生することを防止することができ、また、副反応生成物のチオ炭酸塩が水溶液中に存在していても、分解されて二硫化炭素が発生することを抑制することができ、更に、重金属固定処理時においても、二硫化炭素の発生を防止することができる。ｐＨ調整剤としては、水酸化カリウム、水酸化ナトリウム、水酸化リチウム等のアルカリを適用することができ、後述するピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩の生成に使用したアルカリ金属の水酸化物と同一のアルカリ金属の水酸化物を好適に使用することもでき、添加量はピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩の０．０１から２００モル％とすることができる。
【００１９】
更に、重金属固定剤は他の物質、例えば、水素イオン濃度を調整するためのアルカリや、酸、また、酸化防止剤、又はメタノールやエタノール等の水溶性有機溶媒等を含有するものであってもよい。
【００２０】
本発明の重金属固定剤の製造方法は、通常のピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有した水溶液の製造後に、ピペラジン又はポリアミンをそのまま、あるいは水溶液として、あるいは、低融点であるピペラジン水和物は溶融して液状として添加してもよい。
【００２１】
また、ピペラジンの場合に、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩の製造工程において、使用する二硫化炭素に対して理論計算上必要とされる量よりも過剰に用いて製造することにより、同様に低温において凝固しない重金属固定剤を得ることができる。この場合に過剰量は、必要量に対して０．０１〜２４重量％の範囲が好ましい。０．０１重量％以下では、凝固点を下げるという低温での安定性にほとんど寄与せず、２４重量％以上では、逆に凝固点が上昇し、低温での安定性が悪くなる。
【００２２】
上記ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液の製造は、加熱溶融したピペラジン水和物、又はピペラジン無水物若しくはピペラジン水和物の水溶液に、アルカリ金属水酸化物及び二硫化炭素を混合して製造することができるが、好ましくは、強アルカリ水溶液からのピペラジンの析出を防止するため、加熱溶融したピペラジン水和物、又はピペラジン無水物若しくはピペラジン水和物の水溶液に、アルカリ金属水酸化物と、二硫化炭素とを交互に、又は、連続して同時に滴下して反応させることが好ましい。上記の反応はｐＨ１０以上に調整されて行なわれることが好ましい。
【００２３】
反応の終点は、例えば水溶液中に分散されている二硫化炭素の粒が消失した時点を目安としてＮＭＲ等で確認して決定される。更に、反応終了後、未反応の二硫化炭素を水溶液から除去するため、窒素によるバブリングを行なうことが望ましい。未反応の二硫化炭素等は、重金属固定剤の加熱や、水素イオン濃度の変動等により水溶液中から分離されるため、当初から除去されていることが望ましい。
【００２４】
反応終了後、水溶液をｐＨ１０以上にして保存すると、保存期間中に二硫化炭素の発生が抑制できるため好ましい。反応生成物の水溶液をｐＨ１０以上として保存するには、金属水酸化物を生成ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩の０．０１から２００モル％添加することができる。
水溶液中のピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩の濃度は、水に溶解できる濃度であれば特に限定されないが、濃度が低い場合に比して、濃度が高い場合に、ピペラジンまたはポリアミンを添加する効果が高く、特に、３５重量％以上の濃度の水溶液が好ましい。
【００２５】
本発明の重金属固定剤の低温安定化方法は、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を含有する水溶液を主成分とする重金属固定剤に、ピペラジンまたはポリアミンを添加するものであれば、特に限定されるものではなく、好ましくは、ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩を３５重量％以上含有する水溶液を主成分として用い、このため、低温で重金属固定剤は凝固せず、液状を維持することができ、重金属固定剤の低温における安定化を図ることができる。
【００２６】
本発明の重金属固定剤を使用して飛灰等を処理する方法は、重金属固定剤を飛灰、溶融飛灰、焼却灰、排水、又は重金属含有土壌等の被処理体と混合すればよく、低温においても、重金属固定剤は凝固することがなく液体であり、含有されるピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸塩が晶析することがなく、常温での処理と同様に処理することができる。即ち、重金属固定剤と被処理体を混合することにより、重金属固定剤に含有されるピペラジンビスカルボジチオ酸が被処理体に含有される重金属と結合し、重金属のキレート錯体が形成され、重金属が高精度に固定され、不溶出化される。
【００２７】
重金属固定剤の使用量は、被処理体中に含有される重金属の量によるが、都市ゴミ焼却炉の焼却灰や、排煙灰等であれば、例えば、これらの被処理体の１〜５重量％程度を使用することができる。また、被処理体の形態や、あるいは重金属の含有量により、適宜、重金属固定剤に水を添加して、使用することができる。
【００２８】
このような重金属固定剤によって処理される被処理体としては、特に限定されるものではなく、重金属が含有されるものであれば、いずれのものに対しても適用することができ、工場排水や、産業廃棄物、都市ゴミの焼却プラントにおいて発生する焼却灰や、焼却プラントから排ガスと共に排出され電気集塵機で捕集されたＥＰ灰やバグフィルターで捕集された灰分等の飛灰、重金属汚染土壌等が挙げられ、これらに含有される重金属は無機化合物、有機化合物のいずれの形態として存在するものも処理対象とされ、重金属固定剤により被処理体に含有される重金属が容易に固定される。
【００２９】
以下に、実施例を挙げてこの発明を更に具体的に説明するが、この発明の範囲はこれらの例示に限定されるものではない。
【００３０】
【実施例】
実施例１
３９重量％濃度のピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸カリウム水溶液１００ｇに、粉末状の無水ピペラジン０．３ｇ、０．５ｇ、１．０ｇ、２．０ｇ、５．０ｇを添加した後、４０℃で加熱溶融して、重金属固定剤を調整した。このように調整した重金属固定剤の凝固点を測定した。その結果を、表１及び図１に示す。
【００３１】
【表１】
実施例２
攪拌棒、温度計、分液ロート２個を付けた１Ｌ４口フラスコに水３９３ｇ、無水ピペラジン１０７．５ｇを仕込み、さらに無水ピペラジン３ｇ（溶液全体に対して０．６重量％相当、理論量の無水ピペラジンに対して２．８重量％過剰（以下、カッコ内の数字は同じ意味を表す。））、５ｇ（１．０重量％、４．７重量％）、１０ｇ（２．０重量％、９．３重量％）、２０ｇ（４．０重量％、１８．６重量％）、５０ｇ（１０．０重量％、４６．５重量％）それぞれ仕込み、溶解後、液温を３５℃にしこの後、攪拌下で４８％水酸化カリウム水溶液３０９ｇと二硫化炭素１９０ｇを、表２に示すようにそれぞれ４分割仕込みで交互に添加した。反応温度３５℃では、液の粘度の増大もなく攪拌は容易であった。そして、反応液中に二硫化炭素の小粒が消失した後、温度３５℃から４０℃に上昇させて２時間攪拌して未反応の二硫化炭素を反応させた。この後、残存する微量の二硫化炭素を除去するため、窒素で５分間バブリングした。この反応で得られた合成液の収量は９９．２％であった。得られた合成液中のピペラジン−Ｎ，Ｎ’−ビスカルボジチオ酸カリウムの含量を測定した結果、３９．０重量％であった。これらの重金属固定剤の凝固点を測定した。結果を、表３及び図２に示す。
【００３３】
【表２】
【００３４】
【表３】
実施例３
３９重量％濃度のピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸カリウム水溶液１００ｇに、テトラエチレンペンタミン（ＴＥＰＡ）０．３ｇ、０．５ｇ、１．０ｇ、２．０ｇ、５．０ｇを添加して、重金属固定剤を調整した。このようにして調整した重金属固定剤の凝固点を測定した結果を、表４及び図３に示す。
【００３６】
【表４】
以上の結果から、所定範囲濃度のピペラジンまたポリアミンを添加した３９重量％ピペラジンジ−Ｎ，Ｎ´−ビスカルボジチオ酸カリウム水溶液からなる重金属固定剤の凝固点は、無添加の重金属固定剤の凝固点より低いことがわかった。
【００３８】
【発明の効果】
以上述べたように、本発明の重金属固定剤は、ピペラジン又はポリアミンの添加により、重金属固定剤の凝固が降下し、低温安定性を有しているため、寒冷地等の低温下でも保持、保管が容易となり、このため、寒冷地での重金属が含有される被処理体の処理を安価、且つ容易に行うことができることから、産業上の利用価値は高いといえる。
【図面の簡単な説明】
【図１】実施例１におけるピペラジン添加量による凝固点の変化を示す図である。
【図２】実施例２におけるピペラジン使用量による凝固点の変化を示す図である。
【図３】実施例３におけるテトラエチレンペンタミン添加量による凝固点の変化を示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to industrial wastewater, industrial waste, incinerated ash generated in an incineration plant for municipal waste, exhaust ash discharged from an incineration plant and the like together with fly ash collected by a bag filter and the like, and exhausted together with exhaust gas from a melting furnace. Melt fly ash collected by a bag filter, heavy metal contained in soil contaminated by heavy metals, etc.Fixes heavy metal fixing agents that prevent heavy metal contamination to the environment, especially fly ash containing heavy metals even in cold regions The present invention relates to a heavy metal fixing agent capable of efficiently performing the treatment of a metal and a method for stabilizing the same at a low temperature.
[0002]
[Prior art]
When treating incinerated ash discharged from incineration plants for industrial wastewater, municipal garbage, industrial waste, etc., fly ash and molten fly ash collected by bag filters etc. from smoke, and soil contaminated with heavy metals. In order to prevent the release of harmful metals such as lead, mercury, chromium and cadmium contained in incinerated ash, fly ash and molten fly ash, etc. There is a method of treating incinerated ash, fly ash, molten fly ash and the like with an acid to extract heavy metals, but there are problems in increasing the volume of waste and treating heavy metals extracted with the acid. For this reason, a treatment with a heavy metal fixing agent, which does not require a special device and does not require a post-treatment, has been adopted. As a heavy metal fixing agent, a liquid chelating agent of an amine derivative having a dithiocarboxyl group as a functional group is widely used because it has a high effect of collecting heavy metals and can be insoluble in rainwater or the like. It is known that an aqueous solution containing N, N'-biscarbodithioate is suitably used. (See Patent Document 1)
[0003]
In treating heavy metal-containing fly ash with a heavy metal fixing agent mainly containing a compound having a dithiocarboxyl group, the heavy metal fixing agent contains 0.1 to 100 mol% of the amine of the main component. There is known a method for stabilizing a heavy metal fixing agent. (See Patent Document 2)
[0004]
The aqueous solution containing piperazine di-N, N'-biscarbodithioate used as such a heavy metal fixing agent is prepared by mixing piperazine and an aqueous alkali solution such as sodium hydroxide and potassium hydroxide under a nitrogen atmosphere. The reaction was carried out by dropping carbon disulfide while stirring at a temperature in the range of 30 to 40 ° C. to produce an aqueous solution containing a high concentration of piperazine di-N, N′-biscarbodithioate.
[0005]
[Patent Document 1]
JP-A-8-224560 [Patent Document 2]
JP-A-9-1110
[Problems to be solved by the invention]
However, the heavy metal fixing agent comprising an aqueous solution containing piperazine di-N, N'-biscarbodithioate produced by the above method has a high concentration of piperazine di-N, N'-biscarbodithioate, for example, If it is 35% by weight or more, the freezing point rises, and when used in a low-temperature cold district, the aqueous solution itself solidifies, so special equipment is required for storage and storage. However, there is a problem that not only the cost is increased but also complicated operations are required, and handling is extremely difficult.
[0007]
The present invention provides a low-temperature stable heavy metal fixing agent that lowers the freezing point and maintains a stable state without solidifying even in cold regions, and a low-temperature stable heavy metal fixing agent that facilitates the treatment of fly ash and the like in cold regions. The purpose of the present invention is to provide a conversion method.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to solve the above-mentioned problems. As a result, a heavy metal fixing agent comprising an aqueous solution containing piperazine di-N, N'-biscarbodithioate contains a predetermined amount of piperazine or polyamine. As a result, it has been found that a heavy metal fixing agent that does not solidify at a low temperature can be obtained, and that the heavy metal fixing agent can be stabilized, and the present invention has been completed.
[0009]
That is, the present invention
(1) A heavy metal fixing agent mainly composed of an aqueous solution containing piperazine di-N, N′-biscarbodithioate, containing 0.01 to 2.5% by weight of piperazine with respect to the main component, and Regarding heavy metal fixing agent characterized by not solidifying,
(2) A heavy metal fixing agent mainly composed of an aqueous solution containing piperazine di-N, N'-biscarbodithioate, which contains 0.01 to 4.5% by weight of a polyamine with respect to the main component, and Regarding heavy metal fixing agent characterized by not solidifying,
(3) Calculated from carbon disulfide used in a heavy metal fixing agent mainly composed of an aqueous solution containing piperazine di-N, N'-biscarbodithioate produced from piperazine, metal hydroxide and carbon disulfide. A heavy metal fixing agent comprising, as a main component, an aqueous solution produced by reacting 0.01 to 24% by weight of piperazine with a metal hydroxide and carbon disulfide over a theoretical amount, and not coagulating at a low temperature;
(4) The heavy metal fixing agent according to any one of (1) to (3), wherein the low temperature is lower than a freezing point in a state where piperazine or polyamine is not added.
(5) The heavy metal fixing agent according to any one of (1) to (4), which contains piperazine di-N, N'-biscarbodithioate in an amount of 35% by weight or more.
[0010]
further,
(6) adding 0.01 to 2.5% by weight of piperazine to a heavy metal fixing agent mainly containing an aqueous solution containing piperazine di-N, N'-biscarbodithioate; Regarding the low-temperature stabilization method of heavy metal fixing agent characterized,
(7) adding 0.01 to 4.5% by weight of polyamine to a heavy metal fixing agent mainly containing an aqueous solution containing piperazine di-N, N'-biscarbodithioate; Regarding the low-temperature stabilization method of heavy metal fixing agent characterized,
(8) An aqueous solution produced by reacting 0.01 to 24% by weight of piperazine with a metal hydroxide or carbon disulfide in excess of a theoretical amount calculated from carbon disulfide to be used is used as a main component. Low-temperature stabilization method of heavy metal fixing agent to be,
(9) The method for stabilizing a heavy metal fixing agent at a low temperature according to any one of (6) to (8), wherein the low temperature is lower than a freezing point in a state where piperazine or polyamine is not added.
(10) The low-temperature heavy metal fixing agent according to any one of (6) to (9), wherein a heavy metal fixing agent containing 35% by weight or more of piperazine di-N, N'-biscarbodithioate is used. It relates to a stabilization method.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
As the piperazine di-N, N'-biscarbodithioate used in the heavy metal fixing agent of the present invention, the salt portion is replaced with a heavy metal atom by being mixed with a fly ash containing a heavy metal. Easily form a chelate complex with, and quickly and firmly fix heavy metal atoms, as long as the fixed heavy metal atoms are not released by rainwater or the like, there is no particular limitation, but specifically, Preferable examples include salts of piperazine biscarbodithioic acid with alkali metals such as potassium, sodium and lithium.
[0012]
Piperazine di-N, N'-biscarbodithioate is produced and isolated as an aqueous solution containing piperazine di-N, N'-biscarbodithioate, which is the main component of the heavy metal fixing agent of the present invention, and is further prepared into an aqueous solution An aqueous solution obtained by mixing piperazine, an alkali metal hydroxide and carbon disulfide in an aqueous solution may be subjected to an operation of removing excess carbon disulfide as necessary, a pH adjustment operation, and the like. It can also be used as it is. The aqueous solution serving as the main component may contain, for example, a compound such as piperazine di-N, -monocarbodithioate in addition to piperazine di-N, N'-biscarbodithioate.
[0013]
The piperazine used in the present invention is used by being dissolved in an aqueous solution containing piperazine di-N, N'-biscarbodithioate, and either piperazine anhydride or piperazine hydrate may be used. Can be. Piperazine anhydride or piperazine hydrate may be used in a solid state or as an aqueous solution added to the heavy metal fixing agent, and piperazine hydrate having a low melting point may be melted and added to the heavy metal fixing agent as a liquid. It may be used. These aqueous solutions of piperazine are basic and have a function of lowering the freezing point of the heavy metal fixing agent and suppressing the generation of carbon disulfide.
[0014]
The content of piperazine is preferably in the range of 0.01 to 2.5% by weight based on the aqueous solution as the main component. If it is less than 0.01% by weight, it hardly contributes to the low-temperature stability of lowering the freezing point, and if it is more than 2.5% by weight, the freezing point increases and the low-temperature stability deteriorates. The low temperature means a temperature lower than the freezing point of piperazine or polyamine in a state where the piperazine or the polyamine is not added at the time of use or storage, and the timing of addition may be before or after the reaction. For example, in the case of piperazine di-N, N'-biscarbodithioate having a concentration of 35% by weight, it can be stably stored and used even at -10 ° C or lower. Hereinafter, in this specification, low temperature is used for the same meaning.
[0015]
The polyamine used in the present invention is used by being dissolved in an aqueous solution containing piperazine di-N, N'-biscarbodithioate, and is easily soluble in water, like piperazine. Is basic and has a function of lowering the freezing point of the heavy metal fixing agent and suppressing the generation of carbon disulfide. The polyamine is not particularly limited as long as it has a plurality of amino groups, and the amino group may be any of a primary amino group, a secondary amino group, and a tertiary amino group. In addition, examples of the polyamine include those having a plurality of amino groups such as diamine, triamine, and tetramine. Aliphatic amines are preferable, and aliphatic amines include aliphatic unsaturated amines and alicyclic ones. Amines and the like can also be applied.
[0016]
As the polyamine, a polyvalent amine having at least one secondary amino group in the molecule is preferable. Specifically, N-methylethylenediamine, N-ethylethylenediamine, N-butylethylenediamine, N, N ′ -Dimethylethylenediamine, N, N'-diethylethylenediamine, N-methyl-1,3-propanediamine, N, N'-dimethyl-1,3-propanediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylene Hexamine, iminobispropylamine, polyethyleneimine, N- (2-aminoethyl) -1,3-propanediamine, N, N'-bis (3-aminopropyl) ethylenediamine, 3,3'-iminobis (N, N '-Dimethylpropylamine), 2,2'-isonodi It can be exemplified methanol, and the like.
[0017]
The content of the polyamine is preferably in the range of 0.01 to 4.5% by weight based on the aqueous solution as the main component. If it is less than 0.01% by weight, it hardly contributes to the low-temperature stability of lowering the freezing point, and if it is more than 4.5% by weight, the freezing point rises conversely, and the low-temperature stability deteriorates.
[0018]
The heavy metal fixing agent of the present invention may contain a pH adjuster for keeping the aqueous solution basic in addition to these polyamines and piperazine. In the case where a pH adjuster is contained, the hydrogen ion concentration during the storage period can be kept within a predetermined range, and the generation of carbon disulfide generated from thiocarbonate, which is a by-product, can be prevented. If the aqueous solution has a hydrogen ion concentration of
[0019]
Further, the heavy metal fixing agent may contain another substance, for example, an alkali or an acid for adjusting the hydrogen ion concentration, an acid, or an antioxidant, or a water-soluble organic solvent such as methanol or ethanol. Good.
[0020]
The method for producing a heavy metal fixing agent according to the present invention is characterized in that, after producing an aqueous solution containing ordinary piperazine di-N, N'-biscarbodithioate, piperazine or polyamine as it is, or as an aqueous solution, or piperazine having a low melting point. The hydrate may be melted and added as a liquid.
[0021]
In addition, in the case of piperazine, in the production process of piperazine di-N, N'-biscarbodithioate, it is produced by using it in excess of the amount theoretically required for carbon disulfide to be used. Similarly, a heavy metal fixing agent which does not solidify at low temperatures can be obtained. In this case, the excess amount is preferably in the range of 0.01 to 24% by weight based on the required amount. If it is less than 0.01% by weight, it hardly contributes to the low-temperature stability of lowering the freezing point, and if it is more than 24% by weight, the freezing point increases and the low-temperature stability deteriorates.
[0022]
The production of the aqueous solution containing piperazine di-N, N'-biscarbodithioate is performed by adding an alkali metal hydroxide and disulfide to an aqueous solution of piperazine hydrate or piperazine anhydride or piperazine hydrate melted by heating. Although it can be produced by mixing carbon, preferably, in order to prevent the precipitation of piperazine from a strongly alkaline aqueous solution, heat-melted piperazine hydrate, or an aqueous solution of piperazine anhydride or piperazine hydrate, It is preferable that the metal hydroxide and the carbon disulfide be dropped and reacted alternately or continuously at the same time. It is preferable that the above reaction is carried out at a pH of 10 or more.
[0023]
The end point of the reaction is determined by confirming with NMR or the like, for example, the time when the carbon disulfide particles dispersed in the aqueous solution disappear. Further, after the completion of the reaction, it is desirable to perform bubbling with nitrogen in order to remove unreacted carbon disulfide from the aqueous solution. Unreacted carbon disulfide and the like are separated from the aqueous solution due to heating of the heavy metal fixing agent, fluctuations in the hydrogen ion concentration, and the like, and thus it is desirable that they be removed from the beginning.
[0024]
After completion of the reaction, it is preferable to store the aqueous solution at
The concentration of piperazine di-N, N'-biscarbodithioate in the aqueous solution is not particularly limited as long as it can be dissolved in water, but when the concentration is higher than when the concentration is low, piperazine or polyamine is used. Is highly effective, and an aqueous solution having a concentration of 35% by weight or more is particularly preferable.
[0025]
The method for stabilizing a heavy metal fixing agent at a low temperature according to the present invention is a method for adding piperazine or polyamine to a heavy metal fixing agent mainly containing an aqueous solution containing piperazine di-N, N'-biscarbodithioate, There is no particular limitation, and preferably, an aqueous solution containing 35% by weight or more of piperazine di-N, N'-biscarbodithioate is used as a main component. Therefore, the heavy metal fixing agent does not solidify at a low temperature, The liquid can be maintained, and the heavy metal fixing agent can be stabilized at a low temperature.
[0026]
The method of treating fly ash or the like using the heavy metal fixing agent of the present invention may be performed by mixing the heavy metal fixing agent with a processing target such as fly ash, molten fly ash, incineration ash, wastewater, or heavy metal-containing soil, Even at low temperatures, the heavy metal fixing agent is a liquid without coagulation, and the contained piperazine di-N, N'-biscarbodithioate does not crystallize, and should be treated in the same manner as at room temperature. Can be. That is, by mixing the heavy metal fixing agent and the object to be treated, piperazine biscarbodithioic acid contained in the heavy metal fixing agent is combined with the heavy metal contained in the object to be treated, and a chelate complex of the heavy metal is formed. It is fixed with high precision and is made non-elutable.
[0027]
The amount of the heavy metal fixing agent used depends on the amount of the heavy metal contained in the object to be treated, but if it is incinerated ash of a city garbage incinerator or smoke ash, for example, 1 to 5 weight of these objects to be treated % Can be used. Further, depending on the form of the object to be treated and the content of heavy metal, water can be appropriately added to the heavy metal fixing agent for use.
[0028]
The object to be treated by such a heavy metal fixing agent is not particularly limited, and any object containing a heavy metal can be applied to any object, such as a factory wastewater or the like. Fly ash, such as incineration ash generated at incineration plants for industrial waste and municipal waste, EP ash discharged along with exhaust gas from the incineration plant and collected by an electrostatic precipitator, and ash collected by a bag filter, and heavy metal contaminated soil The heavy metals contained in these substances are present in any form of inorganic compounds and organic compounds, and the heavy metals contained in the object are easily fixed by the heavy metal fixing agent.
[0029]
Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these exemplifications.
[0030]
【Example】
Example 1
0.3 g, 0.5 g, 1.0 g, 2.0 g, 5.0 g of powdered anhydrous piperazine was added to 100 g of a 39 wt% aqueous solution of potassium piperazine di-N, N'-biscarbodithioate, The mixture was heated and melted at 40 ° C. to prepare a heavy metal fixing agent. The solidification point of the heavy metal fixing agent thus adjusted was measured. The results are shown in Table 1 and FIG.
[0031]
[Table 1]
Example 2
393 g of water and 107.5 g of anhydrous piperazine were charged into a 1 L four-necked flask equipped with a stirring rod, a thermometer, and two separating funnels, and 3 g of anhydrous piperazine (0.6% by weight based on the whole solution, a theoretical amount of anhydrous 2.8% by weight relative to piperazine (the numbers in parentheses indicate the same meaning hereinafter), 5 g (1.0% by weight, 4.7% by weight), 10 g (2.0% by weight, 9% by weight) 0.3% by weight), 20 g (4.0% by weight, 18.6% by weight), and 50 g (10.0% by weight, 46.5% by weight), respectively. Under stirring, 309 g of a 48% aqueous solution of potassium hydroxide and 190 g of carbon disulfide were added alternately in four portions as shown in Table 2. At a reaction temperature of 35 ° C., stirring was easy without increasing the viscosity of the liquid. After the small particles of carbon disulfide disappeared in the reaction solution, the temperature was raised from 35 ° C. to 40 ° C., and the mixture was stirred for 2 hours to react unreacted carbon disulfide. Thereafter, nitrogen was bubbled for 5 minutes in order to remove the remaining trace of carbon disulfide. The yield of the synthesis solution obtained by this reaction was 99.2%. As a result of measuring the content of potassium piperazine-N, N'-biscarbodithioate in the obtained synthesis solution, it was 39.0% by weight. The freezing points of these heavy metal fixing agents were measured. The results are shown in Table 3 and FIG.
[0033]
[Table 2]
[0034]
[Table 3]
Example 3
0.3 g, 0.5 g, 1.0 g, 2.0 g, and 5.0 g of tetraethylenepentamine (TEPA) were added to 100 g of a 39% by weight aqueous solution of potassium piperazine di-N, N'-biscarbodithioate. Thus, a heavy metal fixing agent was prepared. The results of measuring the freezing point of the heavy metal fixing agent thus adjusted are shown in Table 4 and FIG.
[0036]
[Table 4]
From the above results, the freezing point of the heavy metal fixing agent composed of a 39% by weight aqueous solution of potassium piperazine di-N, N'-biscarbodithioate to which piperazine or polyamine of a predetermined range was added was lower than the freezing point of the heavy metal fixing agent without addition. I understand.
[0038]
【The invention's effect】
As described above, the heavy metal fixing agent of the present invention is reduced in solidification of the heavy metal fixing agent by the addition of piperazine or polyamine, and has low-temperature stability. Therefore, it is possible to easily and inexpensively treat an object containing a heavy metal in a cold region, and thus it can be said that industrial use value is high.
[Brief description of the drawings]
FIG. 1 is a graph showing a change in freezing point depending on the amount of piperazine added in Example 1.
FIG. 2 is a graph showing a change in freezing point according to the amount of piperazine used in Example 2.
FIG. 3 is a graph showing a change in freezing point depending on the amount of tetraethylenepentamine added in Example 3.
Claims (10)
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| JP2005334799A (en) * | 2004-05-28 | 2005-12-08 | Miyoshi Oil & Fat Co Ltd | Waste disposal method and heavy metal immobilizing treatment agent composition |
| JP2006316183A (en) * | 2005-05-13 | 2006-11-24 | Tosoh Corp | Heavy metal treatment agent and heavy metal treatment method using the same |
| JP2007183204A (en) * | 2006-01-10 | 2007-07-19 | Tosoh Corp | Judgment method of heavy metal fixation effect |
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