JP4178794B2 - Iron sulfide, method for producing the same, iron sulfide composition, treatment agent for heavy metals, and treatment method using the same - Google Patents

Description

また、本明細書にいう変性マキナワイト構造とは、上記表１に示されるマキナワイト構造のＸＲＤの回折パターンにおいて、００１面の面間隔が５．０３Å以上５．５３Å以下とｃ軸方向に広がり、この００１面からのピーク強度を１００とした場合、他のｈｋｌ面からの回折ピークの強度比がすべて２０以下であることにより特徴づけられる構造を意味する。
【００２１】
変性マキナワイト構造となる原因は明らかではないが、硫化鉄が生成する際にアルカリ土類金属成分が存在していた場合、硫化鉄中へアルカリ土類金属が、ｃ軸すなわち鉄原子層とイオウ原子層の間隔を広げ、かつ、ａ軸及びｂ軸すなわち鉄原子及びイオウ原子の並びの乱れを生じさせるように取り込まれるためと推定される。
【００２２】
上記した変性マキナワイト構造の硫化鉄の検討を行なった結果、変性マキナワイト構造の硫化鉄は、これを水に分散し、酢酸のような弱酸を添加した後、濾過洗浄を行なうことにより、アルカリ土類金属の一部が溶出し、ＸＲＤ回折パターンがマキナワイト構造に可逆的に変化することを見出した。従って、本発明の変性マキナワイト構造とは、これまで知られていたマキナワイト構造の特殊形態であると考えられる。
【００２３】
次に本発明の硫化鉄の製造方法について詳細に説明する。
【００２４】
本発明の方法は、２価の鉄塩の水溶液と硫黄イオンを含む水溶液とアルカリ土類金属成分を混合し、かつ、混合後のスラリーｐＨを７．０以上とすることにより、耐久性に優れたマキナワイト構造の硫化鉄を得るものである。
【００２５】
本発明の方法では、上記した３つの成分の混合順序は適宜選択することができ、２価の鉄塩の水溶液と硫黄イオンを含む水溶液を混合した後にアルカリ土類金属成分を混合してもよく、また、２価の鉄塩の水溶液とアルカリ土類金属成分を混合しその後硫黄イオンを含む水溶液と混合しても良く、また、硫黄イオンを含む水溶液とアルカリ土類金属成分を混合し、２価の鉄塩の水溶液を混合しても良く、生産プロセス上最適な方法を選択することができる。
本発明者が更に、上記した混合方法において、２価の鉄塩の水溶液と硫黄イオンを含む水溶液を混合し硫化鉄が生成する際にアルカリ土類金属が存在した場合は、生成するマキナワイト構造の硫化鉄は変性マキナワイト構造となることを見出した。
【００２６】
本発明の方法において用いられる２価の鉄塩の水溶液は、水溶性の２価の鉄塩であれば特に限定されず、具体的には塩化鉄（ＩＩ）、硝酸鉄（ＩＩ）、硫酸鉄（ＩＩ）酢酸鉄（ＩＩ）等を例示することができる。この中で、塩化鉄（ＩＩ）が工業的に入手が容易で安価なために最も好ましく、また、鉄屑等を塩酸で溶解した溶液や、鉄板を塩酸で洗浄した後の廃液等も好ましく用いることができる。一方、硫酸鉄（ＩＩ）は、アルカリ土類金属成分がＣａ、Ｓｒ、Ｂａの場合はこれらと難溶性の塩を作りやすいため、原料の混合を注意深くゆっくり行なわなければならず好ましいものではないが、アルカリ土類金属成分がＭｇの場合は好適に用いることができる。
【００２７】
用いられる２価の鉄塩の水溶液の濃度は特に限定されないが、濃度が薄すぎると反応槽の容積が大きくなり、さらに濾過を行なうスラリーの量が増大するため工業的に不利となることがある。逆に濃度が濃すぎると、温度の変動による塩の析出等のトラブルが生じ易くなり、また、生成するスラリーの粘度が高くなりハンドリングや均一な混合が困難になることがある。従って具体的な２価の鉄塩の濃度としては、Ｆｅとして１〜２５ｗｔ％、より好ましくは３〜２０ｗｔ％の範囲を例示することができる。
【００２８】
本発明の方法において用いられる硫黄イオンを含む溶液は、硫黄イオンを含むものであれば特に限定されず、アルカリ金属塩の硫化物や水硫化物、アンモニウム塩の硫化物や水硫化物、アルカリ土類金属の硫化物や水硫化物を水に溶解したものであればすべて好適に用いることができる。この中でも硫化ナトリウムや水硫化ナトリウムが、工業的に入手が容易で安価なために最も好ましく、また、石油の脱硫工程で得られる硫化水素を水酸化ナトリウム等のアルカリ水溶液に吸収させた溶液も好ましく用いることができる。
【００２９】
用いられる硫黄イオンを含む溶液の濃度は特に限定されないが、２価の鉄塩の水溶液の濃度と同様の理由である。具体的な硫黄イオンの濃度としては、Ｓとして１〜１５ｗｔ％、より好ましくは２〜１０ｗｔ％の範囲を例示することができる。
【００３０】
アルカリ土類金属成分は水溶性のものであれば特に限定されず、また、炭酸塩のように水溶性を示さないものであっても酸性溶液に溶解するものも使用が可能である。具体的なアルカリ土類金属成分としてはアルカリ土類金属の塩化物やカルボン酸塩、硝酸塩、水酸化物、硫化物を例示することができる。
【００３１】
２価の鉄塩の水溶液と硫黄イオンを含む水溶液との混合割合は特に限定されないが、硫黄イオンが多すぎた場合、原料コストが高くなるだけでなく、未反応の硫黄イオンが母液中に残存し廃水処理が必要となることがある。逆に少なすぎた場合は過剰の鉄分が水酸化鉄として沈澱し、硫化鉄と水酸化物の混合物が得られ、硫化鉄の特性の低下は生じないものの、水酸化鉄の重量分だけ硫化鉄が希釈され見かけの特性が低下する。従って、ＦｅとＳのモル比は、１：０．７〜１．８、さらに好ましくは１：０．８〜１．５の範囲になるように混合することが好ましい。
【００３２】
２価の鉄塩の水溶液とアルカリ土類金属成分の混合割合はアルカリ土類金属の種類により異なるが、アルカリ土類金属の量が少ないと本発明の耐久性に優れたマキナワイト構造を有する硫化鉄は得られない。従って、アルカリ土類金属成分がマグネシウム（Ｍｇ）の場合ＦｅとＭｇのモル比が、１：０．０４以上となるように混合することが好ましく、アルカリ土類金属成分がカルシウム（Ｃａ）の場合ＦｅとＣａのモル比が、１：０．０３以上なるように混合することが好ましく、アルカリ土類金属成分がストロンチウム（Ｓｒ）の場合ＦｅとＳｒのモル比が、１：０．０２以上となるように混合することが好ましく、アルカリ土類金属成分がバリウム（Ｂａ）の場合ＦｅとＢａのモル比が、１：０．０１以上となるように混合することが好ましい。
【００３３】
混合操作は特に限定されず、化学工学で知られている半回分式方法または連続式を用いることができる。
【００３４】
混合時の温度は特に限定されず、冷却及び加熱する必要はなく、例えば１０〜６０℃の温度を例示することができる。
【００３５】
混合時の撹拌は特に限定されず、生成する硫化鉄を含んだスラリーの滞留が生じないような撹拌強度であれば特に問題はない。
【００３６】
原料の混合速度は特に限定されないが、混合があまり遅いと生産性が低下することがあり、速すぎると局部的な滞留や粘度の上昇が起きる可能性がある。従って、例えば半回分式の場合１〜２４０分で、より好ましくは３〜１２０分ですべての原料が混ざるような添加速度を選択すればよく、また連続法では原料の供給速度を平均滞留時間が１０〜２４０分、より好ましくは１５〜１２０分となるようにすればよい。
【００３７】
以上のように、混合操作が終了した時点で本発明の硫化鉄を含むスラリーが得られる。本発明では、混合操作終了時のスラリーｐＨが７．０以上となっていることが必須である。スラリーｐＨを７．０以上とするために混合終了後にアルカリ源を添加してもよいが、予めアルカリ源を硫黄イオンを含む水溶液に添加しておくことがより好ましい。アルカリ源は特に限定されず、アルカリ金属の水酸化物、アルカリ土類金属の水酸化物等を例示でき、具体的には水酸化ナトリウム、水酸化カリウム、水酸化カルシウム、水酸化バリウム等を例示できる。スラリーｐＨが７．０未満の場合、アルカリ土類金属が硫化鉄内に取り込まれず本発明の硫化鉄は得られない。スラリーｐＨは高いほど好ましく、８．０以上、より好ましくは１０．０以上、さらに好ましくは１２．０前後とすることがよい。
【００３８】
また、原料の混合が終了した後、生成したスラリー全体を均一にするために、そのまま撹拌を継続し、熟成を行なってもよい。熟成時間は特に限定されず、例えば０〜３００分の時間を例示することができる。
【００３９】
以上の方法で本発明の硫化鉄を含んだスラリーが得られる。このスラリーをそのまま重金属類の処理に用いてもよいが、輸送コストが多大なものとなり、また、高濃度の重金属類を含んだ飛灰や土壌を処理するために多量の硫化鉄を添加する場合、被処理物の含水量が高くなりすぎ、そのあとのハンドリングが困難となる可能性がある。そのため、通常は濾過・洗浄を行なった後、乾燥を行ない硫化鉄の粉末とする。
【００４０】
このときの濾過・洗浄の方法としては公知の方法を用いることができるが、濾過・洗浄が不十分であると、硫化鉄中に残存するアルカリ金属のため耐久性に優れた硫化鉄を得ることは困難となる。従って、濾過・洗浄条件は、濾過・洗浄後に得られる硫化鉄中の鉄とアルカリ金属のモル比が、鉄のモル比を１とした場合、アルカリ金属の値が０．２以下、より好ましくは０．１以下となるような条件とすることが必要である。
【００４１】
乾燥は従来知られているどのような方法で行なっても良いが、硫化鉄の酸化を防ぐために、不活性雰囲気ガス中での乾燥あるいは真空乾燥がより好ましく用いることができる。
【００４２】
以上の方法で本発明の硫化鉄を得ることができる。
【００４３】
本発明者らは更に検討を加えた結果、本発明の組成の硫化鉄に各種のアルカリ土類金属化合物を加えることにより、本発明の目的の一つである重金属類の処理剤としてより好適に用いることができる硫化鉄組成物が得られることを見出した。この硫化鉄組成物は、本発明の組成の硫化鉄を調製し、これに別途添加して混合する、例えばボールミル等で機械的に混合するなどして調製するか、或いは本発明の組成の硫化鉄の範囲を超えたアルカリ土類金属成分を過剰に使用して調製することも可能である。
【００４４】
添加或いは過剰に使用するアルカリ土類金属化合物としては、アルカリ土類の水酸化物、カルボン酸塩、リン酸塩、亜硫酸塩、硫酸塩、炭酸塩等が例示できる。更に詳しくは、水酸化マグネシウム、水酸化カルシウム、水酸化ストロンチウム、水酸化バリウム、酢酸、ぎ酸、しゅう酸、クエン酸、ステアリン酸などの対応するアルカリ土類金属塩、また、例えば、リン酸水素カルシウム等のリン酸、ポリリン酸の対応するアルカリ土類金属塩、炭酸マグネシウム、炭酸カルシウムなどのアルカリ土類金属の炭酸塩、硫酸マグネシウム、硫酸カルシウム、硫酸バリウムなどのアルカリ土類金属の硫酸塩、更には、酸化防止機能などを有する亜硫酸、アスコルビン酸などのアルカリ土類金属塩などが例示できる。
【００４５】
これらのアルカリ土類金属化合物は本発明の硫化鉄の耐久性を低下させることがなく、また、その種類に応じて、硫化鉄の担体効果による重金属処理活性向上作用、耐久性の向上作用、重金属類の処理時の補助剤、ハンドリンク性の向上、等の作用を有しており、目的により１種以上複数種のアルカリ土類金属塩を本発明の硫化鉄に添加して用いることもできる。例えば、酸性の飛灰を処理する場合、アルカリ剤を補助剤として添加することが好ましく、その場合、本発明の硫化鉄とアルカリ土類の水酸化物の混合物が好適に用いることができ、また、多量の６価クロムのような酸化成分が大量に含まれている場合は、本発明の硫化鉄と亜硫酸塩の混合物が好適に用いることができる。また、本発明の硫化鉄は耐久性に優れているが、本発明者らはアルカリ土類のカルボン酸塩、とくに酢酸塩を加えることによりその耐久性は更に向上することを見出しており、過酷な保存条件が考えられるときにはこれらを添加することができる。
【００４６】
これらのアルカリ土類金属化合物の添加量は特に限定されず、目的に応じて変化し、例えば本発明の硫化鉄１００重量部に対し０．１〜１００重量部添加することができる。
【００４７】
本発明の硫化鉄および硫化鉄組成物は、極めて耐久性に優れ、これを有効成分とする「重金属類処理剤」として用いた場合、きわめて高い性能を発揮する。以下、本発明の重金属類処理剤について、その詳細を説明する。
【００４８】
本発明の重金属類処理剤では、その処理が可能な重金属類とは具体的な元素として、Ｐｂ、Ｃｄ、Ｃｒ、Ｈｇ、Ａｓ、Ｓｅ、Ｃｕ、Ｎｉ、Ｓｂ、Ｍｏを示すことができる。もちろん、本発明の処理剤では上記した重金属類をそれぞれ単独に処理するだけでなく、これらの内の任意の複数の元素が含まれたものを処理する場合においても処理が可能である。
【００４９】
本発明の重金属類処理剤は、重金属類を含んだごみ焼却灰や飛灰の処理に極めて有効である。ごみ焼却灰や飛灰中には、各種ごみに含まれていた重金属類が濃縮されている。特に飛灰や溶融飛灰において顕著であり、溶融飛灰の中にはパーセントオーダーで鉛のような重金属が含まれているものも数多く、無害化処理が必要とされる。飛灰や溶融飛灰は焼却炉の構造や運転方法の違いにより、アルカリ性飛灰、中性飛灰、アルカリ性溶融飛灰、中性溶融飛灰等の種類があり、また、焼却するごみの種類によって含まれる重金属類の種類と含有量は大きく異なっていることが知られているが、本発明の重金属類処理剤はどのような種類の飛灰にも用いることができる。これらごみ焼却灰や飛灰に対し、本発明の重金属類処理剤と水を添加し混練する。
【００５０】
本発明の重金属類処理剤の添加量は、ごみ焼却灰や飛灰に含まれる重金属類の種類と総量により異なるため一概に規定できず、ごみ焼却灰や飛灰の量に対して、０．１〜５０ｗｔ％、好ましくは０．５〜３０ｗｔ％を例示することができ、さらに、予めごみ焼却灰や飛灰をサンプリングしてラボテストで最小添加量を求め、ごみ焼却灰や飛灰に含まれる重金属類の量の変動を考慮して最適添加量を求めておくことが好ましい。また、仮に過剰添加を行なっても、例えば水銀（Ｈｇ）が多硫化物となり可溶性となるような現象は生じず、問題はない。
【００５１】
水の添加量はごみ焼却灰や飛灰の性質により異なるが、通常、ごみ焼却灰や飛灰の量に対して、１０〜４０ｗｔ％を例示することができる。混練の方法、時間は特に限定されず従来から知られている方法を用いることができ、可溶性の重金属類は不溶性の硫化物または鉄塩となり処理が行われる。
【００５２】
また、本発明の重金属類処理剤は、重金属類を含んだ土壌の処理にも有効である。重金属類を含んだ土壌に対して、重金属類処理剤を、さらに必要に応じて、水を添加し、混練する。
【００５３】
本発明の重金属類処理剤の添加量は、土壌に含まれる重金属類の総量により異なるため一概に規定できず、処理すべき土壌の量に対して０．１〜２０ｗｔ％を例示することができ、さらに、予め土壌をサンプリングしてラボテストで最小添加量を求め、安全を見込んで若干過剰量を添加することが好ましい。土壌に含まれる水分が少ない場合は、土壌の種類によっても異なるが、必要に応じて水を添加し、土壌に含まれる水分の量が通常１０〜６０ｗｔ％となるようにする。混練の方法、時間は特に限定されず従来から知られている方法を用いることができ、可溶性の重金属類は不溶性の硫化物または鉄塩となり処理が行われる。
【００５４】
さらに、本発明の重金属類処理剤を用い、重金属類を含んだ廃水の処理も可能である。重金属類を含んだ廃水に対して、重金属類処理剤を添加し混合する。重金属類処理剤の添加量は、廃水に含まれる重金属類の総量により異なるため一概に規定できず、予め廃水をサンプリングしてラボテストで最小添加量を求め、安全を見込んで若干過剰量を添加することが好ましい。この時に、廃水のｐＨが低いと硫化鉄が分解し硫化水素の生成の可能性があるため、廃水のｐＨを前もって調整しておくことが好ましく、その場合には廃水のｐＨは３．０以上、より好ましくは６．０以上となるようにする。混合の方法、時間は特に限定されず従来から知られている方法を用いることができ、廃水中の重金属類は不溶性の硫化物または鉄塩となり処理が行われる。また、通常、凝集沈澱処理の際に使用される無機系凝集沈澱剤、例えば塩化第２鉄、ポリ塩化アルミニウム、硫酸バンド等を併用し、あるいは凝集速度を速める高分子凝集剤等を併用することも可能である。
【００５５】
【実施例】
以下、実施例において本発明をさらに詳細に説明する。しかし、本発明はこれら実施例のみに限定されるものではない。尚、実施例における各測定方法は以下の通りである。
【００５６】
（１）化学組成の測定方法
Ｆｅ、Ｓ、Ｃａ、Ｓｒ、Ｂａは、蛍光Ｘ線分析装置（日本電子社製、型式ＪＳＸ−３２００）を用いて測定した。また、Ｎａ、Ｍｇ、Ｆｅは試料を塩酸で溶解した後、ＩＣＰ発光分析装置（パーキンエルマー社製、型式：ｏｐｔｉｍａ ３０００）を用いて測定した。測定後、鉄を基準としてアルカリ土類金属元素、アルカリ金属元素、硫黄のモル比を求めた。
【００５７】
（２）結晶構造の測定方法
Ｘ線回折装置（マックサイエンス社製、型式：ＭＸＰ−３、Ｃｕターゲット）を用い測定した。
【００５８】
（３）硫化鉄の残存率
耐久処理前の硫化鉄のメインピーク強度をＩ１、耐久処理後の硫化鉄のメインピーク強度をＩ２として、
硫化鉄残存率（％）＝Ｉ２／Ｉ１×１００ として計算した。
【００５９】
実施例１
実効内容積７５０ｍＬのステンレス製連続反応容器を２５℃に保ち、攪拌しながら塩化鉄（ＩＩ）水溶液（０．５ｍｏｌ／Ｌ）と硫化ナトリウム水溶液（１．０ｍｏｌ／Ｌ）をそれぞれ５００ｍｌ／ｈ、２５０ｍｌ／ｈで連続的に添加し、硫化鉄スラリーを調製した。
【００６０】
得られた硫化鉄スラリーのうち１０００ｍｌを内容積２Ｌのガラス製反応容器に入れ、攪拌しながら塩化カルシウム８３ｍｍｏｌを添加し、さらに４８％ＮａＯＨ水溶液を加え、スラリーｐＨを１２．８とした。このまま６０分攪拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。このときのＸ線回折のチャートを図１及び図２に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｃａ_0.22・Ｎａ_0.016・Ｓ_1.00であった。
【００６１】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はＸ線回折の結果マキナワイト構造であり、硫化鉄の分解生成物である硫黄、および酸化鉄（ＩＩＩ）のピークは観察されなかった。このときのＸ線回折のチャートを図１に示す。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、８５％であった。
【００６２】
実施例２
スラリーｐＨを１１．７とした以外、実施例１と全く同じ操作を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。このときのＸ線回折のチャートを図２に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｃａ_0.073・Ｎａ_0.032・Ｓ_0.99であった。
【００６３】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はＸ線回折の結果マキナワイト構造であり、硫化鉄の分解生成物である硫黄のピークがわずかに観察された。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、７１％であった。
【００６４】
実施例３
スラリーｐＨを１０．３とした以外、実施例１と全く同じ操作を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。このときのＸ線回折のチャートを図２に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｃａ_0.035・Ｎａ_0.077・Ｓ_0.99であった。
【００６５】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はＸ線回折の結果、マキナワイト構造硫化鉄以外に分解生成物である硫黄に帰属できるピークが観察された。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、５３％であった。
【００６６】
実施例４
添加した塩化カルシウムの量を２２０ｍｍｏｌ、スラリーｐＨを１２．６とした以外、実施例１と全く同じ操作を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果、マキナワイト構造の硫化鉄以外に水酸化カルシウムのピークが観察された。組成分析の結果、各成分のモル比は、Ｆｅ・Ｃａ_0.43・Ｎａ_0.004・Ｓ_0.98であった。
【００６７】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はＸ線回折の結果、マキナワイト構造の硫化鉄以外に水酸化カルシウムおよび炭酸カルシウムのピークが観察された。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、８７％であった。
【００６８】
比較例１
実施例１と同様の方法で連続的に調製した硫化鉄スラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。このときのＸ線回折のチャートを図３に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｎａ_0.22・Ｓ_0.99であった。
【００６９】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はＸ線回折の結果、硫化鉄の分解生成物である硫黄と酸化鉄（ＩＩＩ）の混合物であり、硫化鉄に帰属できるピークは観察されなかった。このときのＸ線回折のチャートを図３に示す。
【００７０】
比較例２
比較例１で調製した硫化鉄粉末３０ｇに水酸化カルシウム４ｇを加え、ボールミルで３０分混合し、硫化鉄と水酸化カルシウムの混合組成物を調製した。この組成物は、Ｘ線回折の結果マキナワイト構造の硫化鉄と水酸化カルシウムの混合物であった。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｃａ_0.19・Ｎａ_0.22・Ｓ_0.99であった。
【００７１】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はＸ線回折の結果、硫化鉄の分解生成物である硫黄と酸化鉄（ＩＩＩ）および水酸化カルシウムと炭酸カルシウムの混合物であり、硫化鉄に帰属できるピークは観察されなかった。
【００７２】
比較例３
塊状の市販試薬硫化鉄（ＩＩ）を粉砕し硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果ピロータイト構造であった。このときのＸ線回折のチャートを図４に示す。
【００７３】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果１ピロータイト構造と、硫化鉄の分解生成物である硫黄に帰属できるピークが観察された。このときのＸ線回折のチャートを図４に示す。
【００７４】
実施例１、比較例１、２、３の結果より、本発明における硫化鉄は、従来知られていた合成硫化鉄より耐久性が大きく向上しており、しかも、添加したカルシウムは単なる混合物ではなく、硫化鉄内に取り込まれていると判断できる。実施例１〜４の結果より、スラリーｐＨが高いほどカルシウムが硫化鉄に取り込まれやすくなり、取り込まれるカルシウムの量が多いほど硫化鉄の安定性が向上することがわかる。さらに、アルカリ土類金属が硫化鉄に取り込まれる量には上限があり、カルシウムの場合では０．４前後であると推定でき、それ以上のカルシウムを導入しようとした場合、水酸化カルシウムとの混合組成物となることがわかる。以上のことより、アルカリ土類金属がカルシウムの場合、鉄に対してカルシウムのモル比が０．０３〜０．４の領域で本発明の耐久性が向上した硫化鉄が得られると判断できる。また、図２において、実施例１で得られた硫化鉄の回折ピークが実施例２、３で得られたものよりも低角度側にシフトしており、硫化鉄にカルシウムが多く取り込まれたためと考えられる。
【００７５】
実施例５
実施例１と同様の方法で連続的に調製した硫化鉄スラリーのうち１０００ｍｌを内容積２Ｌのガラス製反応容器に入れ、攪拌しながら塩化バリウム８３ｍｍｏｌを添加し、さらに４８％ＮａＯＨ水溶液を加え、スラリーｐＨを１３．０とした。このまま６０分攪拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。このときのＸ線回折のチャートを図５に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｂａ_0.078・Ｎａ_0.014・Ｓ_0.96であった。
【００７６】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末はマキナワイト構造であり、硫化鉄の分解生成物である硫黄、および酸化鉄（ＩＩＩ）のピークは観察されなかった。このときのＸ線回折のチャートを図５に示す。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、９３％であった。
【００７７】
実施例６
実施例１と同様の方法で連続的に調製した硫化鉄スラリーのうち１０００ｍｌを内容積２Ｌのガラス製反応容器に入れ、攪拌しながら塩化ストロンチウム６６ｍｍｏｌを添加し、さらに４８％ＮａＯＨ水溶液を加え、スラリーｐＨを１３．１とした。このまま６０分攪拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｓｒ_0.095・Ｎａ_0.023・Ｓ_0.98であった。
【００７８】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果マキナワイト構造であり、硫黄、および酸化鉄（ＩＩＩ）のピークは観察されなかった。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、８８％であった。
【００７９】
実施例７
実施例１と同様の方法で連続的に調製した硫化鉄スラリーのうち１０００ｍｌを内容積２Ｌのガラス製反応容器に入れ、攪拌しながら塩化マグネシウム１３０ｍｍｏｌを添加し、さらに４８％ＮａＯＨ水溶液を加え、スラリーｐＨを１２．９とした。このまま６０分攪拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果マキナワイト構造であった。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｍｇ_0.37・Ｎａ_0.068・Ｓ_0.95であった。
【００８０】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果マキナワイト構造であり、硫化鉄の分解生成物である硫黄に帰属できるピークがわずかに観察された。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、７２％であった。
【００８１】
実施例５〜７の結果より、カルシウム以外のアルカリ土類金属にも合成硫化鉄の耐久性を向上する作用があることがわかる。
【００８２】
実施例８
内容積２リットルのガラス製反応容器に市販試薬の水硫化ナトリウム４８０ｍｍｏｌ、水酸化ナトリウム７２０ｍｍｏｌ、水１０００ｇを入れ撹拌・溶解しながらウォーターバスを用い２５℃に保った。この溶液に、水６００ｇに塩化鉄（ＩＩ）４８０ｍｍｏｌ、塩化カルシウム１２０ｍｍｏｌを溶解した溶液を４０分かけて添加した。添加終了後のスラリーのｐＨは、１２．３であった。このまま３０分撹拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った、変性マキナワイト構造であった。このときのＸ線回折のチャートを図６及び図８に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｃａ_0.16・Ｎａ_0.006・Ｓ_0.90であった。
【００８３】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った変性マキナワイト構造であり、硫化鉄の分解生成物である硫黄、および酸化鉄（ＩＩＩ）のピークは観察されなかった。このときのＸ線回折のチャートを図６に示す。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、９１％であった。
【００８４】
また、得られた硫化鉄粉末の一部を用いて、夏場から秋にかけて３ヶ月の室内保存試験を行なった。保存試験後の粉末は、Ｘ線回折の結果変性マキナワイト構造であり、硫化鉄の分解生成物である硫黄、および酸化鉄（ＩＩＩ）のピークは観察されなかった。
【００８５】
実施例９
内容積２リットルのガラス製反応容器に市販試薬の水硫化ナトリウム４８０ｍｍｏｌ、水酸化ナトリウム７２０ｍｍｏｌ、水１０００ｇを入れ撹拌・溶解しながらウォーターバスを用い２５℃に保った。この溶液に、水６００ｇに塩化鉄（ＩＩ）４８０ｍｍｏｌ、塩化バリウム１２０ｍｍｏｌを溶解した溶液を４０分かけて添加した。添加終了後のスラリーのｐＨは、１２．６であった。このまま３０分撹拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った、変性マキナワイト構造であった。このときのＸ線回折のチャートを図７に示す。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｂａ_0.083・Ｎａ_0.028・Ｓ_0.88であった。
【００８６】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った変性マキナワイト構造であり、硫化鉄の分解生成物である硫黄に帰属できるピークがわずかに観察された。このときのＸ線回折のチャートを図７に示す。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、８７％であった。
【００８７】
実施例１０
内容積２リットルのガラス製反応容器に市販試薬の水硫化ナトリウム４８０ｍｍｏｌ、水酸化ナトリウム７２０ｍｍｏｌ、水１０００ｇを入れ撹拌・溶解しながらウォーターバスを用い２５℃に保った。この溶液に、水６００ｇに塩化鉄（ＩＩ）４８０ｍｍｏｌ、塩化ストロンチウム１２０ｍｍｏｌを溶解した溶液を４０分かけて添加した。添加終了後のスラリーのｐＨは、１２．４であった。このまま３０分撹拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った、変性マキナワイト構造であった。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｓｒ_0.097・Ｎａ_0.019・Ｓ_0.92であった。
【００８８】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った変性マキナワイト構造であり、硫化鉄の分解生成物である硫黄、および酸化鉄（ＩＩＩ）のピークは観察されなかった。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、９３％であった。
【００８９】
実施例１１
内容積２リットルのガラス製反応容器に市販試薬の水硫化ナトリウム４２０ｍｍｏｌ、水酸化ナトリウム７８０ｍｍｏｌ、水１０００ｇを入れ撹拌・溶解しながらウォーターバスを用い２５℃に保った。この溶液に、水６００ｇに硫酸鉄（ＩＩ）４２０ｍｍｏｌ、硫酸マグネシウム１８０ｍｍｏｌを溶解した溶液を４０分かけて添加した。添加終了後のスラリーのｐＨは、１０．５であった。このまま３０分撹拌を継続し熟成を行なった。熟成後得られたスラリーを濾過・洗浄した後、乾燥し、粉砕を行ない硫化鉄粉末を得た。得られた硫化鉄粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った、変性マキナワイト構造であった。また組成分析の結果、各成分のモル比は、Ｆｅ・Ｍｇ_0.37・Ｎａ_0.079・Ｓ_0.94であった。
【００９０】
次に、得られた硫化鉄粉末の一部を７０℃、相対湿度７０％の恒温恒湿機に入れ、１日耐久処理を行なった。耐久処理後の粉末は、Ｘ線回折の結果１７〜１８°付近にブロードなピークを持った変性マキナワイト構造以外に、硫化鉄の分解生成物である硫黄に帰属できるピークがわずかに観察された。耐久処理前後におけるメインピークの強度比をもとに硫化鉄の残存率を計算した結果、７８％であった。
【００９１】
実施例８〜１１の結果により、アルカリ土類金属成分の存在下で、２価の鉄塩の水溶液と硫黄イオンを含む水溶液を混合した場合には、変性マキナワイト構造の硫化鉄が得られることがわかる。
【００９２】
実施例１２
用いる水硫化ナトリウムの量を４２０ｍｍｏｌ水酸化ナトリウムの量を７８０ｍｍｏｌ、塩化鉄（ＩＩ）の量を４２０ｍｍｏｌ、塩化カルシウムの量を１８０ｍｍｏｌとして実施例８と同じ操作を行なった。
【００９３】
添加終了後のスラリーｐＨは１２．６、得られた粉末は変性マキナワイト構造の硫化鉄、各成分のモル比はＦｅ・Ｃａ_0.28・Ｎａ_0.002・Ｓ_0.88であった。このときのＸ線回折のチャートを図８に示す。また、耐久処理後の粉末は変性マキナワイト構造の硫化鉄であり、硫化鉄の残存率は８８％であった。
【００９４】
実施例１３
用いる水硫化ナトリウムの量を３６０ｍｍｏｌ水酸化ナトリウムの量を８４０ｍｍｏｌ、塩化鉄（ＩＩ）の量を３６０ｍｍｏｌ、塩化カルシウムの量を２４０ｍｍｏｌとして実施例８と同じ操作を行なった。
【００９５】
添加終了後のスラリーｐＨは１２．５、得られた粉末は変性マキナワイト構造の硫化鉄でありトレース量の水酸化カルシウムのピークが観察され、各成分のモル比はＦｅ・Ｃａ_0.39・Ｎａ_0.001・Ｓ_0.91であった。このときのＸ線回折のチャートを図８に示す。また、耐久処理後の粉末は変性マキナワイト構造の硫化鉄であり、トレース量の水酸化カルシウムと炭酸カルシウムのピークが観察され、硫化鉄の残存率は９３％であった。
【００９６】
実施例１４
用いる水硫化ナトリウムの量を３００ｍｍｏｌ水酸化ナトリウムの量を９００ｍｍｏｌ、塩化鉄（ＩＩ）の量を３００ｍｍｏｌ、塩化カルシウムの量を３００ｍｍｏｌとして実施例８と同じ操作を行なった。
【００９７】
添加終了後のスラリーｐＨは１２．５、得られた粉末は変性マキナワイト構造の硫化鉄と水酸化カルシウムの混合物であった。各成分のモル比はＦｅ・Ｃａ_0.66・Ｎａ_0.001・Ｓ_0.88であった。このときのＸ線回折のチャートを図８に示す。また、耐久処理後の粉末は変性マキナワイト構造の硫化鉄と水酸化カルシウムと炭酸カルシウムの混合物であり、硫化鉄の残存率は９３％であった。
【００９８】
実施例１５
用いる水硫化ナトリウムの量を５４０ｍｍｏｌ水酸化ナトリウムの量を６６０ｍｍｏｌ、塩化鉄（ＩＩ）の量を２７０ｍｍｏｌ、塩化カルシウムの量を６０ｍｍｏｌとして実施例８と同じ操作を行なった。
【００９９】
添加終了後のスラリーｐＨは１１．１、得られた粉末は変性マキナワイト構造の硫化鉄であり、各成分のモル比はＦｅ・Ｃａ_0.038・Ｎａ_0.089・Ｓ_0.85であった。このときのＸ線回折のチャートを図８に示す。また、耐久処理後の粉末は変性マキナワイト構造の硫化鉄とその分解生成物の硫黄の混合物であり、硫化鉄の残存率は５６％であった。
【０１００】
比較例４
用いる水硫化ナトリウムの量を６００ｍｍｏｌ水酸化ナトリウムの量を６００ｍｍｏｌ、塩化鉄（ＩＩ）の量を６００ｍｍｏｌ、塩化カルシウムの量を１０ｍｍｏｌとして実施例５と同じ操作を行なった。
【０１０１】
添加終了後のスラリーｐＨは６．８、得られた粉末はマキナワイト構造の硫化鉄であり、各成分のモル比はＦｅ・Ｃａ_0.008・Ｎａ_0.14・Ｓ_0.94であった。また、耐久処理後の粉末は硫化鉄の分解生成物である硫黄と酸化鉄（ＩＩ）の混合物であり、硫化鉄に帰属できるピークは観察されなかった。
【０１０２】
実施例１〜５、１２〜１５の結果より、マキナワイト構造の硫化鉄より、変性マキナワイト構造であるほうがより耐久性が向上していると考えられる。また、比較例４の結果より、添加終了後のスラリーｐＨが７未満の場合、カルシウムの存在下で硫化鉄を調製しても、カルシウムが取り込まれず、耐久性が向上しないことがわかる。
【０１０３】
次に本発明の硫化鉄を用いて重金属類の処理を行なった結果を示す。
【０１０４】
実施例１６
鉛を２４００ｐｐｍ、クロムを１６０ｐｐｍ、水銀を２．１ｐｐｍ含有するアルカリ性飛灰を用い、重金属類の処理特性の検討を行なった。アルカリ性飛灰１００重量部に対し、水３０重量部、および実施例、比較例で調製した硫化鉄を加え、混練し重金属処理を行なった。得られた処理飛灰に対し、環境庁告示第１３号溶出試験（１９７３年）を行ない、その結果を表２に示した。
【０１０５】
【表２】

表２の結果から明らかなように、実施例で得た硫化鉄は、耐久処理前の重金属類の処理特性はマキナワイト型の硫化鉄とほぼ同等であり、比較例で得たピロータイト型の硫化鉄よりはるかに優れていることがわかる。さらに、従来のマキナワイト型の硫化鉄は、７０℃、相対湿度７０％で１日耐久処理を行なった場合、重金属類の処理特性が劣化してしまうのに対し、本発明における硫化鉄は耐久処理後も重金属類の処理特性を維持していることがわかる。
【０１０６】
実施例１７
鉛を１９００ｐｐｍ、クロムを１１００ｐｐｍ、カドミウムを１００ｐｐｍ含有する中性飛灰を用い、重金属類の処理特性の検討を行なった。中性飛灰１００重量部に対し、水３０重量部、および実施例、比較例で調製した硫化鉄を加え、混練し重金属処理を行なった。得られた処理飛灰に対し、環境庁告示第１３号溶出試験（１９７３年）を行ない、その結果を表３に示した。
【０１０７】
【表３】

表３の結果から明らかなように、実施例８及び９で得た硫化鉄は、中性飛灰に含まれる重金属類の処理も可能であり、さらに比較例１で得た従来の合成硫化鉄とほぼ同等の初期特性を持ち、しかもはるかに耐久性が優れていることがわかる。
【０１０８】
実施例１８
鉛を７７００ｐｐｍ、カドミウムを４７０ｐｐｍ、６価クロムを１８００ｐｐｍ、ヒ素を９６ｐｐｍ、セレンを２２００ｐｐｍ含有するモデル汚染土壌（含水量５０％）を用い、重金属類の処理特性の検討を行なった。土壌１００重量部に対し、実施例、比較例で調製した硫化鉄を加え、混練し重金属処理を行なった。得られた土壌に対し、環境庁告示第４６号による溶出試験（１９９１年）を行ない、その結果を表４及び表５に示した。
【０１０９】
【表４】

【表５】

表４及び５の結果から明らかなように、実施例１、８で得た硫化鉄は、土壌に含まれる重金属類の処理も可能であり、比較例１で得たマキナワイト型の硫化鉄とほぼ同等の初期特性を持ち、さらにマキナワイト型の硫化鉄よりもはるかに耐久性が優れていることがわかる。
【０１１０】
実施例１９
鉛１０ｐｐｍを含む溶液、カドミニウム１０ｐｐｍ含む溶液、水銀１ｐｐｍを含む溶液、六価クロム１０ｐｐｍを含む溶液、砒素１０ｐｐｍを含む溶液、セレン１０ｐｐｍを含む溶液の６種類のモデル排水に対し、実施例１および８で調製した硫化鉄を０．２重量部添加し、硫化鉄による重金属類の処理特性の検討を行なった。モデル排水に硫化鉄を加えた後、３０分混合し、ガラス濾紙（アドバンテック東洋製ＧＳ−２５）で濾過後、濾液中に含まれている各成分の量を測定した。その結果を表６に示した。
【０１１１】
【表６】

表６の結果から明らかなように、本発明における硫化鉄は、排水中の重金属類の処理も可能である。
【０１１２】
【発明の効果】
本発明によれば、以下の効果を奏する。
１）本発明の硫化鉄は、従来知られていなかった新規な組成のマキナワイト構造を有し、重金属類の処理特性が優れると共に、その耐久性も優れている。
２）本発明の製造方法は、この優れた硫化鉄を容易に製造することができる。
３）本発明の重金属類処理剤は、この優れた硫化鉄を有効成分として含むものであり、この処理剤を用いることで、灰、土壌、廃水等に含まれる重金属類を処理し無害化できる。
【図面の簡単な説明】
【図１】実施例１で調製した硫化鉄粉末、およびそれを７０℃、相対湿度７０％で１日耐久処理を行なった後のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図２】実施例１、実施例２、実施例３で調製した硫化鉄粉末のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図３】比較例１で調製した硫化鉄粉末、およびそれを７０℃、相対湿度７０％で１日耐久処理を行なった後のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図４】比較例３で調製した硫化鉄粉末、およびそれを７０℃、相対湿度７０％で１日耐久処理を行なった後のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図５】実施例５で調製した硫化鉄粉末、およびそれを７０℃、相対湿度７０％で１日耐久処理を行なった後のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図６】実施例８で調製した硫化鉄粉末、およびそれを７０℃、相対湿度７０％で１日耐久処理を行なった後のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図７】実施例９で調製した硫化鉄粉末、およびそれを７０℃、相対湿度７０％で１日耐久処理を行なった後のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【図８】実施例８、実施例１２、実施例１３、実施例１４、実施例１５で調製した硫化鉄粉末のＸ線回折の結果を示す。Ｘ軸（横軸）は回折角２θ（単位は、ｄｅｇｒｅｅ）を示し、Ｙ軸（縦軸）はＸ線の強度（単位はｃｐｓ）を示す。
【符号の説明】
１：実施例１で調製した硫化鉄粉末のＸ線回折パターン
２：実施例１で調製した硫化鉄粉末を耐久処理した後のＸ線回折パターン
３：実施例１で調製した硫化鉄粉末のＸ線回折パターン
４：実施例２で調製した硫化鉄粉末のＸ線回折パターン
５：実施例３で調製した硫化鉄粉末のＸ線回折パターン
６：比較例１で調製した硫化鉄粉末のＸ線回折パターン
７：比較例１で調製した硫化鉄粉末を耐久処理した後のＸ線回折パターン
８：比較例３で調製した硫化鉄粉末のＸ線回折パターン
９：比較例３で調製した硫化鉄粉末を耐久処理した後のＸ線回折パターン
１０：実施例５で調製した硫化鉄粉末のＸ線回折パターン
１１：実施例５で調製した硫化鉄粉末を耐久処理した後のＸ線回折パターン
１２：実施例８で調製した硫化鉄粉末のＸ線回折パターン
１３：実施例８で調製した硫化鉄粉末を耐久処理した後のＸ線回折パターン
１４：実施例９で調製した硫化鉄粉末のＸ線回折パターン
１５：実施例９で調製した硫化鉄粉末を耐久処理した後のＸ線回折パター
１６：実施例１４で調製した硫化鉄粉末のＸ線回折パターン
１７：実施例１３で調製した硫化鉄粉末のＸ線回折パターン
１８：実施例１２で調製した硫化鉄粉末のＸ線回折パターン
１９：実施例８で調製した硫化鉄粉末のＸ線回折パターン
２０：実施例１５で調製した硫化鉄粉末のＸ線回折パターン[0001]
[Technical field to which the invention belongs]
The present invention uses a novel iron sulfide excellent in durability, a method for producing the same, an iron sulfide composition containing the same, a heavy metal treating agent containing the novel iron sulfide as an active ingredient, and the heavy metal treating agent. The present invention relates to a detoxification method for waste containing various heavy metals.
[0002]
[Prior art]
Reviews of Pure and Applied Chemistry, Vol. 20, pp. 175-206 (1970) shows the structure of iron sulfide, which is made by melting commonly known industrial iron sulfide, iron powder and sulfur. It is disclosed that the iron sulfide obtained has a pyrotite structure, and the iron sulfide produced by mixing a solution containing iron (II) ions and a solution containing sulfur ions has a macinaite structure.
[0003]
It is widely known to use iron sulfide to detoxify waste containing various heavy metals. For example, Japanese Patent Publication Nos. 49-43472, 47-31806, and 50- No. 13294, JP-A-50-96053, JP-A-52-126665, JP-A-60-227881, etc. A method for treating harmful heavy metals such as Cd, Cr, Hg, As and the like is disclosed.
[0004]
In addition, it is also known to treat heavy metals using iron sulfide (makinawite structure) prepared by mixing a solution containing iron (II) ions and a solution containing sulfur ions, and obtained by this method. It is known that iron sulfide has a higher ability to treat heavy metals than industrial iron sulfide. For example, JP-A-48-11291, JP-A-49-31152, JP-A-52-113559, JP-A-52-148473, JP-A-53-102273, etc. (II) A method of treating harmful heavy metals using a solution containing ions and a solution containing sulfur ions, or iron sulfide obtained by mixing these solutions is disclosed.
[0005]
However, the iron sulfide having a makinawite structure is very easily oxidized, reacts with moisture and oxygen in the air, decomposes into sulfur and iron (III) hydroxide, and easily reduces the ability to treat heavy metals. Therefore, conventionally, a solution containing iron (II) ions and a solution containing sulfur ions are mixed to prepare a slurry containing iron sulfide, and the slurry is immediately mixed with an object to be treated such as waste water. It was customary. Usually, a solution containing sulfur ions uses sodium sulfide or aqueous sodium hydrosulfide solution because of its price and industrial availability. However, a skilled person who has knowledge of chemistry due to its harmfulness, corrosiveness, bad odor, etc. However, it was necessary to perform operation, and general handling was difficult. Furthermore, when used in a slurry, it is difficult to increase the concentration of iron sulfide in order to have a certain fluidity. For example, when iron sulfide slurry is produced in a factory, the transportation cost becomes large, and wastewater When used for treatment, etc., no problem occurs, but for example when adding a large amount of iron sulfide to treat fly ash or soil containing high concentrations of heavy metals, the water content of the treated material becomes too high, There were problems such as subsequent handling becoming difficult.
[0006]
On the other hand, when preparing the makinawite-structured iron sulfide powder by filtering and drying the slurry, it was necessary to operate in an inert atmosphere or add an antioxidant to prevent oxidation. It was necessary to store the obtained iron sulfide powder in a container that does not allow oxygen and moisture to permeate, or to add a reducing agent for preventing oxidation so as not to cause oxidative deterioration. Even when a reducing agent is added, the ease of oxidative degradation has not been fundamentally solved, and since the oxidation of iron sulfide starts when the reducing agent is consumed, the storage stability is extremely low.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a novel iron sulfide excellent in durability and processing characteristics of heavy metals, an iron sulfide composition containing the novel iron sulfide, and a method for synthesizing these in the background described above. There is. Furthermore, it is also an object of the present invention to provide a heavy metal treating agent containing the iron sulfide as an active ingredient, and a method for treating and detoxifying heavy metals contained in ash, soil, waste water, etc. using the treating agent. And
[0008]
[Means for Solving the Problems]
The present inventors have studied the above problem, that is, conventional synthetic iron sulfide has a drawback that it has a high treatment activity of heavy metals but is inferior in durability. Incorporating a certain amount or more of similar metals, and as an essential component of the constituent elements, Fe · M _x ・ N _y ・ S _z (Wherein, M is an alkaline earth metal, N is an alkali metal, x, y and z are molar ratios, 0.01 <x ≦ 0.5, y ≦ 0.2, 0.7 ≦ z ≦ 1. It is found that the durability can be remarkably improved by using the iron sulfide having a novel composition represented by the formula (4), and such an iron sulfide is an aqueous solution of a divalent iron salt. And an aqueous solution containing sulfur ions and an alkaline earth component, and the slurry pH after mixing was found to be 7.0 or higher. Furthermore, this new heavy metal treatment agent containing iron sulfide as an active ingredient has been found to have significantly better treatment characteristics of various heavy metals than conventional synthetic iron sulfide and iron sulfide with a pyrotite structure. The invention has been completed.
[0009]
Hereinafter, the present invention will be described in detail.
[0010]
The iron sulfide of the present invention contains Fe.M as an essential component of the constituent elements. _x ・ N _y ・ S _z (In the formula, M is an alkaline earth metal, N is an alkali metal, x, y and z are molar ratios, 0.01 <x ≦ 0.5, y ≦ 0.1, 0.7 ≦ z ≦ 1. .4 is required).
[0011]
In general, it is known that the iron / sulfur molar ratio of iron sulfide is non-stoichiometric, and an arbitrary value can be taken at a molar ratio of about 1. In the iron sulfide of the present invention, the molar ratio z of sulfur to iron shows a value of 0.7 or more and 1.4 or less, similarly to the iron sulfide having the conventional makinawite structure. In order to obtain a more stable makinawite structure, 0.8 or more and 1.0 or less are preferable.
[0012]
The amount of the alkaline earth metal in the iron sulfide of the present invention is represented by a molar ratio x to iron, and x is in the range of 0.01 <x ≦ 0.5. When the molar ratio x is 0.01 or less, improvement in durability cannot be expected. On the other hand, when x exceeds 0.5, the stabilization improvement effect obtained is less than that within this range. .
[0013]
The iron sulfide containing the alkaline earth metal having the composition of the present invention exhibits different XRD depending on the order of adding the alkaline earth metal during preparation. That is, after mixing an aqueous solution containing a divalent iron salt and sulfur ions, when an alkaline earth metal component is added and the pH is set to 7 or higher, XRD attributed to the makinawite structure is shown, and in the presence of the alkaline earth metal component. When an aqueous solution containing a divalent iron salt and sulfur ions is mixed to have a pH of 7 or more, a modified macinaite structure described later is shown. In any case, the inventors found that no peak derived from the alkaline earth metal component was observed within the composition range of the present invention, and that the durability improvement effect was extremely large within this range. It is what I found. Furthermore, when an alkaline earth metal component exceeding this composition range is added, a peak attributed to the alkaline earth metal component compound is observed, and the durability improvement effect is less than that. It is almost equivalent to that of the composition. However, the optimum range in which this effect is recognized is slightly different depending on the type of alkaline earth metal, 0.04 ≦ x ≦ 0.5 for magnesium, 0.03 ≦ x ≦ 0.4 for calcium, and 0 for strontium. 0.02 ≦ x ≦ 0.3, and for barium, 0.01 ≦ x ≦ 0.2.
[0014]
In the present invention, it is possible to use a plurality of kinds of the above-mentioned four elements in any combination as the kind of alkaline earth metal. The most preferred alkaline earth metal in the present invention is calcium and magnesium among the above-mentioned four elements. Calcium and magnesium are not only easily incorporated into iron sulfide, but also easily available industrially, are not as expensive as strontium, and toxicity is not a problem as barium does.
[0015]
In the amount of alkali metal in the iron sulfide of the present invention, the upper limit of y, which is the molar ratio to iron, is lower than that in the case of iron sulfide having a makinawite structure known so far, and it is essential that it is 0.2 or less. is there. When the amount of alkali metal is larger than 0.2, it is difficult to obtain iron sulfide excellent in durability, which is the object of the present invention, and as the amount of alkali metal is small, improvement in durability can be expected, and it is more preferable. Has an alkali metal content of 0.1 or less. Incidentally, the iron sulfide of the present invention includes cases in which no alkali metal is contained. For example, the iron sulfide can be produced using a material that does not contain an alkali metal as a raw material, or by removing the alkali metal component by washing or the like. An iron sulfide can be obtained. Since the type of alkali metal varies depending on the raw material used, it cannot be generally stated. For example, when sodium sulfide or sodium hydrosulfide, which is industrially easily available, is used as a raw material for sulfur ions, N in the above composition formula is sodium. Become.
[0016]
In the present invention, durability was evaluated by changing temperature and relative humidity. Mackinaite structure iron sulfide by conventional synthesis method decomposes in one day at summer temperature (~ 30 ° C) and relative humidity (~ 70%), S peak in XRD starts to be observed, complete in 7 days The peak that can be attributed to the makinawite structure disappears. Furthermore, under conditions of 50 ° C. and a relative humidity of 70%, it completely decomposes in one day, and the peak that can be attributed to the makinawite structure disappears. On the other hand, the iron sulfide of the present invention has a residual rate of 50% or more (decomposition rate is less than 50%) even when the durability treatment is carried out for one day under more severe conditions of 70 ° C. and relative humidity of 70%. It is characterized by extremely improved durability.
[0017]
The reason why the durability is improved by adding the alkaline earth metal is not clear, but the alkaline earth metal is incorporated into the iron sulfide and a layer that prevents oxidative decomposition is formed on the surface of the iron sulfide, or It is presumed that alkaline earth metals hinder the progress of oxidative decomposition.
[0018]
In addition, the alkaline earth metal incorporated in iron sulfide is not incorporated by replacing iron in iron sulfide, but is incorporated in the form of hydroxide or oxide of alkaline earth metal. Presumed.
[0019]
The makinawite structure referred to in the present invention is shown in JCPDS card (Powder Diffraction File) 15-37, and its XRD diffraction pattern is as shown in Table 1 below.
[0020]
[Table 1]

The modified makinawite structure referred to in the present specification refers to the XRD diffraction pattern of the makinawite structure shown in Table 1 above, in which the plane spacing of the 001 plane is 5.03 mm or more and 5.53 mm or less and spreads in the c-axis direction. When the peak intensity from the 001 plane is 100, it means a structure characterized by the fact that all diffraction peak intensity ratios from other hkl planes are 20 or less.
[0021]
The cause of the modified makinawite structure is not clear, but when an alkaline earth metal component is present when iron sulfide is formed, the alkaline earth metal is c-axis, ie, an iron atom layer and a sulfur atom. It is presumed that the distance between the layers is increased and the a-axis and the b-axis, that is, the disorder of the arrangement of iron atoms and sulfur atoms is taken in.
[0022]
As a result of studying the iron sulfide having the modified makinawite structure described above, the iron sulfide having the modified makinawite structure was dispersed in water, added with a weak acid such as acetic acid, and then filtered and washed to obtain alkaline earth. It was found that part of the metal was eluted and the XRD diffraction pattern was reversibly changed to a makinawite structure. Therefore, the modified makinawite structure of the present invention is considered to be a special form of the makinawite structure known so far.
[0023]
Next, the method for producing iron sulfide of the present invention will be described in detail.
[0024]
The method of the present invention is excellent in durability by mixing an aqueous solution of a divalent iron salt, an aqueous solution containing sulfur ions, and an alkaline earth metal component, and setting the slurry pH after mixing to 7.0 or more. In this way, iron sulfide having a makinawite structure is obtained.
[0025]
In the method of the present invention, the mixing order of the above-mentioned three components can be selected as appropriate, and the alkaline earth metal component may be mixed after mixing the aqueous solution of the divalent iron salt and the aqueous solution containing sulfur ions. Alternatively, an aqueous solution of a divalent iron salt and an alkaline earth metal component may be mixed and then mixed with an aqueous solution containing sulfur ions, or an aqueous solution containing sulfur ions and an alkaline earth metal component may be mixed and An aqueous solution of a valent iron salt may be mixed, and an optimum method in the production process can be selected.
Further, the present inventor further mixed an aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions in the above-described mixing method, and when an alkaline earth metal is present when iron sulfide is generated, the generated makinawite structure is formed. It was found that iron sulfide has a modified makinawite structure.
[0026]
The aqueous solution of the divalent iron salt used in the method of the present invention is not particularly limited as long as it is a water-soluble divalent iron salt, and specifically, iron (II) chloride, iron (II) nitrate, iron sulfate. (II) Iron acetate (II) etc. can be illustrated. Among them, iron (II) chloride is most preferable because it is industrially easily available and inexpensive, and a solution obtained by dissolving iron scraps with hydrochloric acid, a waste liquid after washing an iron plate with hydrochloric acid, or the like is also preferably used. be able to. On the other hand, iron (II) sulfate is not preferable because when alkaline earth metal components are Ca, Sr, and Ba, it is easy to form a hardly soluble salt with them, and the raw materials must be carefully and slowly mixed. When the alkaline earth metal component is Mg, it can be preferably used.
[0027]
The concentration of the aqueous solution of the divalent iron salt used is not particularly limited. However, if the concentration is too low, the volume of the reaction vessel increases, and the amount of slurry to be filtered increases, which may be industrially disadvantageous. . On the other hand, if the concentration is too high, troubles such as salt precipitation due to temperature fluctuations are likely to occur, and the viscosity of the resulting slurry increases, which may make handling and uniform mixing difficult. Therefore, the specific concentration of the divalent iron salt can be exemplified by the range of 1 to 25 wt%, more preferably 3 to 20 wt% as Fe.
[0028]
The solution containing sulfur ions used in the method of the present invention is not particularly limited as long as it contains sulfur ions. Alkali metal salt sulfides and hydrosulfides, ammonium salt sulfides and hydrosulfides, alkaline earths Any metal sulfide or hydrosulfide dissolved in water can be suitably used. Among these, sodium sulfide and sodium hydrosulfide are most preferable because they are industrially easily available and inexpensive, and a solution obtained by absorbing hydrogen sulfide obtained in the desulfurization process of petroleum in an alkaline aqueous solution such as sodium hydroxide is also preferable. Can be used.
[0029]
Although the density | concentration of the solution containing the sulfur ion used is not specifically limited, It is the same reason as the density | concentration of the aqueous solution of a bivalent iron salt. As a specific sulfur ion concentration, S can be exemplified by a range of 1 to 15 wt%, more preferably 2 to 10 wt%.
[0030]
The alkaline earth metal component is not particularly limited as long as it is water-soluble, and even if it does not show water solubility such as carbonate, it can be used that dissolves in an acidic solution. Specific examples of the alkaline earth metal component include alkaline earth metal chlorides, carboxylates, nitrates, hydroxides, and sulfides.
[0031]
The mixing ratio of the divalent iron salt aqueous solution and the aqueous solution containing sulfur ions is not particularly limited, but when there are too many sulfur ions, not only the raw material cost increases, but unreacted sulfur ions remain in the mother liquor. Wastewater treatment may be required. On the other hand, when the amount is too small, excess iron precipitates as iron hydroxide, and a mixture of iron sulfide and hydroxide is obtained. Is diluted and apparent properties are deteriorated. Therefore, it is preferable to mix so that the molar ratio of Fe and S is in the range of 1: 0.7 to 1.8, more preferably 1: 0.8 to 1.5.
[0032]
The mixing ratio of the divalent iron salt aqueous solution and the alkaline earth metal component varies depending on the type of the alkaline earth metal, but when the amount of the alkaline earth metal is small, the iron sulfide having the makinawite structure excellent in durability of the present invention. Cannot be obtained. Therefore, when the alkaline earth metal component is magnesium (Mg), it is preferable to mix so that the molar ratio of Fe and Mg is 1: 0.04 or more. When the alkaline earth metal component is calcium (Ca) It is preferable to mix so that the molar ratio of Fe and Ca is 1: 0.03 or more. When the alkaline earth metal component is strontium (Sr), the molar ratio of Fe and Sr is 1: 0.02 or more. It is preferable to mix so that the molar ratio of Fe to Ba is 1: 0.01 or more when the alkaline earth metal component is barium (Ba).
[0033]
The mixing operation is not particularly limited, and a semi-batch method or a continuous method known in chemical engineering can be used.
[0034]
The temperature at the time of mixing is not specifically limited, It is not necessary to cool and heat, For example, the temperature of 10-60 degreeC can be illustrated.
[0035]
Stirring at the time of mixing is not particularly limited, and there is no particular problem as long as the stirring strength does not cause retention of the slurry containing iron sulfide to be generated.
[0036]
The mixing speed of the raw materials is not particularly limited, but if the mixing is too slow, the productivity may be reduced, and if it is too fast, local stagnation and increase in viscosity may occur. Therefore, for example, in the case of a semi-batch type, the addition rate should be selected such that all the raw materials are mixed in 1 to 240 minutes, more preferably 3 to 120 minutes. The time may be 10 to 240 minutes, more preferably 15 to 120 minutes.
[0037]
As described above, the slurry containing the iron sulfide of the present invention is obtained when the mixing operation is completed. In the present invention, it is essential that the slurry pH at the end of the mixing operation is 7.0 or more. An alkali source may be added after mixing to make the slurry pH 7.0 or more, but it is more preferable to add the alkali source to the aqueous solution containing sulfur ions in advance. The alkali source is not particularly limited, and examples thereof include alkali metal hydroxides and alkaline earth metal hydroxides. Specific examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide. it can. When the slurry pH is less than 7.0, the alkaline earth metal is not taken into the iron sulfide and the iron sulfide of the present invention cannot be obtained. The slurry pH is preferably as high as possible, and is preferably 8.0 or more, more preferably 10.0 or more, and still more preferably around 12.0.
[0038]
Further, after the mixing of the raw materials is completed, in order to make the entire slurry generated uniform, stirring may be continued as it is and aging may be performed. The aging time is not particularly limited, and for example, a time of 0 to 300 minutes can be exemplified.
[0039]
The slurry containing the iron sulfide of the present invention is obtained by the above method. This slurry may be used for the treatment of heavy metals as it is, but the transportation cost becomes significant, and when a large amount of iron sulfide is added to treat fly ash and soil containing high concentrations of heavy metals The water content of the object to be processed becomes too high, and subsequent handling may be difficult. Therefore, it is usually filtered and washed and then dried to obtain iron sulfide powder.
[0040]
As a method of filtration / washing at this time, a known method can be used. However, if filtration / washing is insufficient, iron sulfide having excellent durability can be obtained because of the alkali metal remaining in the iron sulfide. Will be difficult. Therefore, the filtration / washing conditions are such that when the molar ratio of iron to alkali metal in the iron sulfide obtained after filtration / washing is 1, the value of alkali metal is 0.2 or less, more preferably It is necessary to set the condition to be 0.1 or less.
[0041]
Although drying may be performed by any conventionally known method, in order to prevent oxidation of iron sulfide, drying in an inert atmosphere gas or vacuum drying can be used more preferably.
[0042]
The iron sulfide of the present invention can be obtained by the above method.
[0043]
As a result of further investigations, the present inventors have added more various alkaline earth metal compounds to the iron sulfide having the composition of the present invention, thereby making it more suitable as a treatment agent for heavy metals that is one of the objects of the present invention. It has been found that an iron sulfide composition that can be used is obtained. This iron sulfide composition is prepared by preparing iron sulfide having the composition of the present invention, and adding and mixing it separately, for example, mechanically mixing with a ball mill or the like, or sulfurizing the composition of the present invention. It is also possible to prepare by using an excess of an alkaline earth metal component exceeding the iron range.
[0044]
Examples of the alkaline earth metal compound added or used in excess include alkaline earth hydroxides, carboxylates, phosphates, sulfites, sulfates, carbonates, and the like. More specifically, the corresponding alkaline earth metal salts such as magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, acetic acid, formic acid, oxalic acid, citric acid, stearic acid, and also, for example, hydrogen phosphate Phosphoric acid such as calcium, corresponding alkaline earth metal salt of polyphosphoric acid, carbonate of alkaline earth metal such as magnesium carbonate and calcium carbonate, sulfate of alkaline earth metal such as magnesium sulfate, calcium sulfate and barium sulfate, Furthermore, alkaline earth metal salts such as sulfurous acid and ascorbic acid having an antioxidant function can be exemplified.
[0045]
These alkaline earth metal compounds do not reduce the durability of the iron sulfide of the present invention, and depending on the type thereof, the heavy metal treatment activity improving action by the support effect of iron sulfide, the durability improving action, heavy metal It has an action such as an auxiliary agent at the time of the treatment of the metal, improvement of hand linkability, etc., and one or more kinds of alkaline earth metal salts can be added to the iron sulfide of the present invention depending on the purpose. . For example, when treating acidic fly ash, it is preferable to add an alkaline agent as an auxiliary agent, in which case the mixture of iron sulfide and alkaline earth hydroxide of the present invention can be suitably used, When a large amount of an oxidizing component such as hexavalent chromium is contained, the mixture of iron sulfide and sulfite of the present invention can be preferably used. Further, although the iron sulfide of the present invention is excellent in durability, the present inventors have found that the durability can be further improved by adding an alkaline earth carboxylate, particularly acetate, which is severe. These can be added when appropriate storage conditions are considered.
[0046]
The addition amount of these alkaline earth metal compounds is not particularly limited, and varies depending on the purpose. For example, 0.1 to 100 parts by weight can be added to 100 parts by weight of iron sulfide of the present invention.
[0047]
The iron sulfide and iron sulfide composition of the present invention are extremely excellent in durability, and exhibit extremely high performance when used as a “heavy metal treating agent” containing this as an active ingredient. Hereinafter, the details of the treatment agent for heavy metals of the present invention will be described.
[0048]
In the heavy metal treating agent of the present invention, the heavy metals that can be treated include Pb, Cd, Cr, Hg, As, Se, Cu, Ni, Sb, and Mo as specific elements. Of course, the treatment agent of the present invention can treat not only each of the above-mentioned heavy metals, but also treatment of those containing any of these elements.
[0049]
The treatment agent for heavy metals of the present invention is extremely effective for treatment of incineration ash and fly ash containing heavy metals. Heavy metals contained in various types of garbage are concentrated in the waste incineration ash and fly ash. This is particularly noticeable in fly ash and molten fly ash, and many of the molten fly ash contain heavy metals such as lead in a percent order, and thus a detoxification treatment is required. Fly ash and molten fly ash are classified into alkaline fly ash, neutral fly ash, alkaline molten fly ash, neutral molten fly ash, etc., depending on the structure and operation method of the incinerator, and the type of garbage to be incinerated. Although it is known that the kind and content of heavy metals contained greatly differ depending on each other, the heavy metal treating agent of the present invention can be used for any kind of fly ash. The heavy metal treating agent of the present invention and water are added to these waste incineration ash and fly ash and kneaded.
[0050]
The amount of addition of the heavy metal treatment agent of the present invention differs depending on the type and total amount of heavy metals contained in the waste incineration ash and fly ash, and thus cannot be defined unconditionally. 1 to 50 wt%, preferably 0.5 to 30 wt% can be exemplified, and further, the incineration ash and fly ash are sampled in advance and the minimum addition amount is obtained by a laboratory test, and is included in the incineration ash and fly ash It is preferable to obtain the optimum addition amount in consideration of fluctuations in the amount of heavy metals. Further, even if excessive addition is performed, for example, a phenomenon that mercury (Hg) becomes polysulfide and becomes soluble does not occur, and there is no problem.
[0051]
The amount of water to be added varies depending on the properties of the waste incineration ash and fly ash, but usually 10 to 40 wt% can be exemplified with respect to the amount of the waste incineration ash and fly ash. The kneading method and time are not particularly limited, and a conventionally known method can be used. The soluble heavy metals are converted into insoluble sulfides or iron salts, and the treatment is performed.
[0052]
The heavy metal treatment agent of the present invention is also effective for treating soil containing heavy metals. A heavy metal treatment agent is further added to the soil containing heavy metals, if necessary, and kneaded.
[0053]
The addition amount of the heavy metal treatment agent of the present invention cannot be defined unconditionally because it varies depending on the total amount of heavy metals contained in the soil, and can be exemplified by 0.1 to 20 wt% with respect to the amount of soil to be treated. Furthermore, it is preferable to sample the soil in advance and obtain the minimum addition amount by a laboratory test, and add a slight excess amount in anticipation of safety. When the amount of water contained in the soil is small, although depending on the type of soil, water is added as necessary so that the amount of water contained in the soil is usually 10 to 60 wt%. The kneading method and time are not particularly limited, and a conventionally known method can be used. The soluble heavy metals are converted into insoluble sulfides or iron salts, and the treatment is performed.
[0054]
Furthermore, wastewater containing heavy metals can be treated using the heavy metal treatment agent of the present invention. A heavy metal treating agent is added to and mixed with wastewater containing heavy metals. The amount of heavy metal treatment agent added varies depending on the total amount of heavy metals contained in the wastewater, so it cannot be specified unconditionally. Sampling the wastewater in advance to obtain the minimum addition amount in a laboratory test, adding a slight excess amount in anticipation of safety It is preferable. At this time, if the pH of the wastewater is low, iron sulfide may decompose and hydrogen sulfide may be generated. Therefore, it is preferable to adjust the pH of the wastewater in advance, in which case the pH of the wastewater is 3.0 or more. More preferably, it should be 6.0 or more. The mixing method and time are not particularly limited, and a conventionally known method can be used, and the heavy metals in the wastewater are treated as insoluble sulfides or iron salts. Ordinarily, inorganic coagulant precipitants used in the coagulation precipitation process, for example, ferric chloride, polyaluminum chloride, sulfuric acid band, etc. are used in combination, or polymer coagulants that increase the coagulation rate are used in combination. Is also possible.
[0055]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In addition, each measuring method in an Example is as follows.
[0056]
(1) Method for measuring chemical composition
Fe, S, Ca, Sr, and Ba were measured using a fluorescent X-ray analyzer (manufactured by JEOL Ltd., model JSX-3200). Na, Mg and Fe were measured using an ICP emission analyzer (manufactured by Perkin Elmer, model: optima 3000) after dissolving the sample with hydrochloric acid. After the measurement, the molar ratio of alkaline earth metal element, alkali metal element, and sulfur was determined based on iron.
[0057]
(2) Crystal structure measurement method
Measurement was performed using an X-ray diffractometer (manufactured by Mac Science, model: MXP-3, Cu target).
[0058]
(3) Residual rate of iron sulfide
The main peak intensity of iron sulfide before endurance treatment is I1, and the main peak intensity of iron sulfide after endurance treatment is I2.
The iron sulfide residual ratio (%) was calculated as I2 / I1 × 100.
[0059]
Example 1
A stainless steel continuous reaction vessel having an effective internal volume of 750 mL is maintained at 25 ° C., and while stirring, an aqueous solution of iron (II) chloride (0.5 mol / L) and an aqueous solution of sodium sulfide (1.0 mol / L) are respectively 500 ml / h and 250 ml. / H was added continuously to prepare an iron sulfide slurry.
[0060]
1000 ml of the obtained iron sulfide slurry was put into a glass reaction vessel having an internal volume of 2 L, 83 mmol of calcium chloride was added with stirring, and a 48% NaOH aqueous solution was further added to make the slurry pH 12.8. In this state, stirring was continued for 60 minutes, and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. The X-ray diffraction charts at this time are shown in FIGS. As a result of composition analysis, the molar ratio of each component is Fe · Ca. _0.22 ・ Na _0.016 ・ S _1.00 Met.
[0061]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment had a makinawite structure, and peaks of sulfur and iron (III) oxide, which are decomposition products of iron sulfide, were not observed. The X-ray diffraction chart at this time is shown in FIG. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 85%.
[0062]
Example 2
Except for the slurry pH being 11.7, the same operation as in Example 1 was performed to obtain an iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. The X-ray diffraction chart at this time is shown in FIG. As a result of composition analysis, the molar ratio of each component is Fe · Ca. _0.073 ・ Na _0.032 ・ S _0.99 Met.
[0063]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment had a makinawite structure, and a slight peak of sulfur, which is a decomposition product of iron sulfide, was observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 71%.
[0064]
Example 3
Except for the slurry pH being 10.3, the same operation as in Example 1 was performed to obtain an iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. The X-ray diffraction chart at this time is shown in FIG. As a result of composition analysis, the molar ratio of each component is Fe · Ca. _0.035 ・ Na _0.077 ・ S _0.99 Met.
[0065]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment was observed to have a peak that can be attributed to sulfur, which is a decomposition product, in addition to the makinawite structure iron sulfide. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 53%.
[0066]
Example 4
Except that the amount of added calcium chloride was 220 mmol and the slurry pH was 12.6, the same operation as in Example 1 was performed to obtain an iron sulfide powder. In the obtained iron sulfide powder, as a result of X-ray diffraction, a peak of calcium hydroxide was observed in addition to iron sulfide having a makinawite structure. As a result of composition analysis, the molar ratio of each component is Fe · Ca. _0.43 ・ Na _0.004 ・ S _0.98 Met.
[0067]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction of the powder after the durability treatment, peaks of calcium hydroxide and calcium carbonate were observed in addition to iron sulfide having a makinawite structure. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 87%.
[0068]
Comparative Example 1
The iron sulfide slurry continuously prepared in the same manner as in Example 1 was filtered and washed, then dried and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. The X-ray diffraction chart at this time is shown in FIG. As a result of composition analysis, the molar ratio of each component was Fe · Na. _0.22 ・ S _0.99 Met.
[0069]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment was a mixture of sulfur and iron (III) oxide, which is a decomposition product of iron sulfide, and no peak attributable to iron sulfide was observed. The X-ray diffraction chart at this time is shown in FIG.
[0070]
Comparative Example 2
4 g of calcium hydroxide was added to 30 g of the iron sulfide powder prepared in Comparative Example 1, and mixed with a ball mill for 30 minutes to prepare a mixed composition of iron sulfide and calcium hydroxide. As a result of X-ray diffraction, this composition was a mixture of iron sulfide and calcium hydroxide having a makinawite structure. As a result of composition analysis, the molar ratio of each component is Fe · Ca. _0.19 ・ Na _0.22 ・ S _0.99 Met.
[0071]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment was a mixture of sulfur and iron oxide (III), which are decomposition products of iron sulfide, and calcium hydroxide and calcium carbonate, and no peak attributable to iron sulfide was observed. .
[0072]
Comparative Example 3
Bulk commercial reagent iron sulfide (II) was pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a pyrotite structure as a result of X-ray diffraction. The X-ray diffraction chart at this time is shown in FIG.
[0073]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after the durability treatment was observed to have a 1 pilotite structure and a peak attributable to sulfur, which is a decomposition product of iron sulfide. The X-ray diffraction chart at this time is shown in FIG.
[0074]
From the results of Example 1 and Comparative Examples 1, 2, and 3, the iron sulfide in the present invention has greatly improved durability over the conventionally known synthetic iron sulfide, and the added calcium is not a mere mixture. It can be judged that it is taken into iron sulfide. From the results of Examples 1 to 4, it can be seen that the higher the slurry pH, the easier the calcium is incorporated into the iron sulfide, and the greater the amount of calcium incorporated, the better the stability of the iron sulfide. Furthermore, there is an upper limit to the amount of alkaline earth metal incorporated into iron sulfide, and in the case of calcium, it can be estimated that it is around 0.4, and if more calcium is to be introduced, it is mixed with calcium hydroxide. It turns out that it becomes a composition. From the above, when the alkaline earth metal is calcium, it can be determined that iron sulfide having improved durability of the present invention can be obtained in a region where the molar ratio of calcium to iron is 0.03 to 0.4. Moreover, in FIG. 2, the diffraction peak of iron sulfide obtained in Example 1 is shifted to a lower angle side than that obtained in Examples 2 and 3, and a large amount of calcium was taken into iron sulfide. Conceivable.
[0075]
Example 5
1000 ml of the iron sulfide slurry continuously prepared in the same manner as in Example 1 was placed in a glass reaction vessel having an internal volume of 2 L, 83 mmol of barium chloride was added with stirring, and a 48% NaOH aqueous solution was further added. The pH was 13.0. In this state, stirring was continued for 60 minutes, and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. The X-ray diffraction chart at this time is shown in FIG. As a result of the composition analysis, the molar ratio of each component is Fe · Ba. _0.078 ・ Na _0.014 ・ S _0.96 Met.
[0076]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. The powder after the endurance treatment had a makinawite structure, and sulfur and iron (III) oxide peaks which were decomposition products of iron sulfide were not observed. The X-ray diffraction chart at this time is shown in FIG. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 93%.
[0077]
Example 6
1000 ml of the iron sulfide slurry continuously prepared in the same manner as in Example 1 was placed in a glass reaction vessel with an internal volume of 2 L, 66 mmol of strontium chloride was added with stirring, and a 48% NaOH aqueous solution was further added. The pH was 13.1. In this state, stirring was continued for 60 minutes, and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. As a result of the composition analysis, the molar ratio of each component was Fe · Sr. _0.095 ・ Na _0.023 ・ S _0.98 Met.
[0078]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment had a makinawite structure, and no sulfur and iron (III) oxide peaks were observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 88%.
[0079]
Example 7
1000 ml of the iron sulfide slurry continuously prepared in the same manner as in Example 1 was placed in a glass reaction vessel having an internal volume of 2 L, 130 mmol of magnesium chloride was added with stirring, and a 48% NaOH aqueous solution was further added. The pH was 12.9. In this state, stirring was continued for 60 minutes, and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a makinawite structure as a result of X-ray diffraction. As a result of composition analysis, the molar ratio of each component was Fe · Mg. _0.37 ・ Na _0.068 ・ S _0.95 Met.
[0080]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after the endurance treatment had a makinawite structure, and a peak attributable to sulfur, which is a decomposition product of iron sulfide, was slightly observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 72%.
[0081]
From the results of Examples 5 to 7, it can be seen that alkaline earth metals other than calcium also have an effect of improving the durability of synthetic iron sulfide.
[0082]
Example 8
A commercially available reagent, sodium hydrosulfide (480 mmol), sodium hydroxide (720 mmol), and water (1000 g) were placed in a glass reaction vessel having an internal volume of 2 liters and kept at 25 ° C. using a water bath while stirring and dissolving. A solution prepared by dissolving 480 mmol of iron (II) chloride and 120 mmol of calcium chloride in 600 g of water was added to this solution over 40 minutes. The pH of the slurry after the addition was 12.3. In this state, stirring was continued for 30 minutes and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. As a result of X-ray diffraction, the obtained iron sulfide powder had a modified makinawite structure having a broad peak in the vicinity of 17 to 18 °. 6 and 8 show X-ray diffraction charts at this time. As a result of composition analysis, the molar ratio of each component is Fe · Ca. _0.16 ・ Na _0.006 ・ S _0.90 Met.
[0083]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment has a modified makinawite structure with a broad peak in the vicinity of 17 to 18 °, and the peaks of sulfur and iron (III) oxide, which are decomposition products of iron sulfide, are observed. Was not. The X-ray diffraction chart at this time is shown in FIG. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 91%.
[0084]
A part of the obtained iron sulfide powder was used for a three-month indoor storage test from summer to autumn. As a result of X-ray diffraction, the powder after the storage test had a modified makinawite structure, and sulfur and iron (III) oxide peaks, which are decomposition products of iron sulfide, were not observed.
[0085]
Example 9
A commercially available reagent, sodium hydrosulfide (480 mmol), sodium hydroxide (720 mmol), and water (1000 g) were placed in a glass reaction vessel having an internal volume of 2 liters and kept at 25 ° C. using a water bath while stirring and dissolving. To this solution, a solution prepared by dissolving 480 mmol of iron (II) chloride and 120 mmol of barium chloride in 600 g of water was added over 40 minutes. The pH of the slurry after the addition was 12.6. In this state, stirring was continued for 30 minutes and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. As a result of X-ray diffraction, the obtained iron sulfide powder had a modified makinawite structure having a broad peak in the vicinity of 17 to 18 °. A chart of X-ray diffraction at this time is shown in FIG. As a result of the composition analysis, the molar ratio of each component is Fe · Ba. _0.083 ・ Na _0.028 ・ S _0.88 Met.
[0086]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after the endurance treatment had a modified makinawite structure having a broad peak in the vicinity of 17 to 18 °, and a slight peak attributable to sulfur, which is a decomposition product of iron sulfide, was observed. A chart of X-ray diffraction at this time is shown in FIG. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 87%.
[0087]
Example 10
A commercially available reagent, sodium hydrosulfide (480 mmol), sodium hydroxide (720 mmol), and water (1000 g) were placed in a glass reaction vessel having an internal volume of 2 liters and kept at 25 ° C. using a water bath while stirring and dissolving. A solution prepared by dissolving 480 mmol of iron (II) chloride and 120 mmol of strontium chloride in 600 g of water was added to this solution over 40 minutes. The pH of the slurry after the addition was 12.4. In this state, stirring was continued for 30 minutes and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. As a result of X-ray diffraction, the obtained iron sulfide powder had a modified makinawite structure having a broad peak in the vicinity of 17 to 18 °. As a result of the composition analysis, the molar ratio of each component was Fe · Sr. _0.097 ・ Na _0.019 ・ S _0.92 Met.
[0088]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. As a result of X-ray diffraction, the powder after endurance treatment has a modified makinawite structure with a broad peak in the vicinity of 17 to 18 °, and the peaks of sulfur and iron (III) oxide, which are decomposition products of iron sulfide, are observed. Was not. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 93%.
[0089]
Example 11
A commercially available reagent, sodium hydrosulfide 420 mmol, sodium hydroxide 780 mmol, and water 1000 g, was placed in a glass reaction vessel having an internal volume of 2 liters and kept at 25 ° C. using a water bath while stirring and dissolving. A solution prepared by dissolving 420 mmol of iron (II) sulfate and 180 mmol of magnesium sulfate in 600 g of water was added to this solution over 40 minutes. The pH of the slurry after the addition was 10.5. In this state, stirring was continued for 30 minutes and aging was performed. The slurry obtained after aging was filtered and washed, then dried and pulverized to obtain iron sulfide powder. As a result of X-ray diffraction, the obtained iron sulfide powder had a modified makinawite structure having a broad peak in the vicinity of 17 to 18 °. As a result of composition analysis, the molar ratio of each component was Fe · Mg. _0.37 ・ Na _0.079 ・ S _0.94 Met.
[0090]
Next, a part of the obtained iron sulfide powder was put into a constant temperature and humidity machine at 70 ° C. and a relative humidity of 70% and subjected to a one-day durability treatment. In addition to the modified makinawite structure having a broad peak in the vicinity of 17 to 18 ° as a result of X-ray diffraction, a peak that can be attributed to sulfur, which is a decomposition product of iron sulfide, was slightly observed in the powder after the durability treatment. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 78%.
[0091]
According to the results of Examples 8 to 11, when an aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions are mixed in the presence of an alkaline earth metal component, iron sulfide having a modified makinawite structure can be obtained. Recognize.
[0092]
Example 12
The same operation as in Example 8 was performed with the amount of sodium hydrosulfide used being 420 mmol, the amount of sodium hydroxide being 780 mmol, the amount of iron (II) chloride being 420 mmol, and the amount of calcium chloride being 180 mmol.
[0093]
The slurry pH after the addition was 12.6, the obtained powder was iron sulfide having a modified macinaite structure, and the molar ratio of each component was Fe · Ca. _0.28 ・ Na _0.002 ・ S _0.88 Met. The X-ray diffraction chart at this time is shown in FIG. Moreover, the powder after the durability treatment was iron sulfide having a modified machinawite structure, and the residual ratio of iron sulfide was 88%.
[0094]
Example 13
The same procedure as in Example 8 was performed, except that the amount of sodium hydrosulfide used was 360 mmol, the amount of sodium hydroxide was 840 mmol, the amount of iron (II) chloride was 360 mmol, and the amount of calcium chloride was 240 mmol.
[0095]
The slurry pH after the addition was 12.5, and the obtained powder was iron sulfide having a modified makinawite structure, and a trace amount of calcium hydroxide peak was observed. The molar ratio of each component was Fe · Ca. _0.39 ・ Na _0.001 ・ S _0.91 Met. The X-ray diffraction chart at this time is shown in FIG. In addition, the powder after the durability treatment was iron sulfide having a modified makinawite structure, and trace amounts of calcium hydroxide and calcium carbonate were observed, and the residual ratio of iron sulfide was 93%.
[0096]
Example 14
The same operation as in Example 8 was performed with the amount of sodium hydrosulfide used being 300 mmol, the amount of sodium hydroxide being 900 mmol, the amount of iron (II) chloride being 300 mmol, and the amount of calcium chloride being 300 mmol.
[0097]
The slurry pH after the addition was 12.5, and the obtained powder was a mixture of iron sulfide and calcium hydroxide having a modified makinawite structure. The molar ratio of each component is Fe · Ca. _0.66 ・ Na _0.001 ・ S _0.88 Met. The X-ray diffraction chart at this time is shown in FIG. The powder after the durability treatment was a mixture of iron sulfide, calcium hydroxide, and calcium carbonate having a modified makinawite structure, and the residual ratio of iron sulfide was 93%.
[0098]
Example 15
The same procedure as in Example 8 was performed, except that the amount of sodium hydrosulfide used was 540 mmol, the amount of sodium hydroxide was 660 mmol, the amount of iron (II) chloride was 270 mmol, and the amount of calcium chloride was 60 mmol.
[0099]
The slurry pH after the addition was 11.1 and the obtained powder was iron sulfide having a modified makinawite structure. The molar ratio of each component was Fe · Ca. _0.038 ・ Na _0.089 ・ S _0.85 Met. The X-ray diffraction chart at this time is shown in FIG. Further, the powder after the durability treatment was a mixture of iron sulfide having a modified makinawite structure and sulfur of the decomposition product thereof, and the residual ratio of iron sulfide was 56%.
[0100]
Comparative Example 4
The amount of sodium hydrosulfide used was 600 mmol, the amount of sodium hydroxide was 600 mmol, the amount of iron (II) chloride was 600 mmol, and the amount of calcium chloride was 10 mmol.
[0101]
The slurry pH after the addition was 6.8, and the obtained powder was iron sulfide having a makinawite structure. The molar ratio of each component was Fe · Ca. _0.008 ・ Na _0.14 ・ S _0.94 Met. Further, the powder after the durability treatment was a mixture of sulfur and iron (II) oxide, which is a decomposition product of iron sulfide, and no peak attributable to iron sulfide was observed.
[0102]
From the results of Examples 1 to 5 and 12 to 15, it is considered that the durability is improved more in the modified makinawite structure than in the iron sulfide having the makinawite structure. Moreover, from the results of Comparative Example 4, it can be seen that when the slurry pH after addition is less than 7, even if iron sulfide is prepared in the presence of calcium, calcium is not taken in and durability is not improved.
[0103]
Next, the result of processing heavy metals using the iron sulfide of the present invention will be shown.
[0104]
Example 16
The processing characteristics of heavy metals were examined using alkaline fly ash containing 2400 ppm lead, 160 ppm chromium, and 2.1 ppm mercury. To 100 parts by weight of alkaline fly ash, 30 parts by weight of water and the iron sulfide prepared in Examples and Comparative Examples were added and kneaded to carry out heavy metal treatment. The obtained treated fly ash was subjected to Environmental Agency Notification No. 13 dissolution test (1973), and the results are shown in Table 2.
[0105]
[Table 2]

table 2 As is apparent from the results, the iron sulfide obtained in the example has almost the same processing characteristics as heavy machinawite type iron sulfide before the endurance treatment, which is higher than the pilotite type iron sulfide obtained in the comparative example. It turns out that it is far superior. Furthermore, when the conventional makinawite-type iron sulfide is subjected to an endurance treatment at 70 ° C. and a relative humidity of 70% for one day, the treatment characteristics of heavy metals are deteriorated, whereas the iron sulfide in the present invention is an endurance treatment. It turns out that the processing characteristic of heavy metals is maintained afterwards.
[0106]
Example 17
Using neutral fly ash containing 1900 ppm lead, 1100 ppm chromium, and 100 ppm cadmium, the processing characteristics of heavy metals were examined. To 100 parts by weight of neutral fly ash, 30 parts by weight of water and iron sulfide prepared in Examples and Comparative Examples were added and kneaded to carry out heavy metal treatment. The Environment Agency Notification No. 13 dissolution test (1973) was conducted on the obtained processed fly ash, and the results were displayed. 3 It was shown to.
[0107]
[Table 3]

table 3 As is apparent from the results, the iron sulfides obtained in Examples 8 and 9 can be used to treat heavy metals contained in neutral fly ash, and are almost the same as the conventional synthetic iron sulfide obtained in Comparative Example 1. It can be seen that they have equivalent initial characteristics and are much more durable.
[0108]
Example 18
The treatment characteristics of heavy metals were examined using model-contaminated soil (water content 50%) containing 7700 ppm lead, 470 ppm cadmium, 1800 ppm hexavalent chromium, 96 ppm arsenic, and 2200 ppm selenium. The iron sulfide prepared in Examples and Comparative Examples was added to 100 parts by weight of soil, kneaded and subjected to heavy metal treatment. The obtained soil was subjected to a dissolution test (1991) according to Notification No. 46 of the Environment Agency, and the results are shown in Tables 4 and 5.
[0109]
[Table 4]

[Table 5]

As is clear from the results in Tables 4 and 5, the iron sulfides obtained in Examples 1 and 8 can be used to treat heavy metals contained in the soil, which is almost the same as the makinawite-type iron sulfide obtained in Comparative Example 1. It can be seen that it has equivalent initial characteristics and is much more durable than makinawite iron sulfide.
[0110]
Example 19
Examples 1 and 8 are applied to six types of model wastewater including a solution containing 10 ppm lead, a solution containing 10 ppm cadmium, a solution containing 1 ppm mercury, a solution containing 10 ppm hexavalent chromium, a solution containing 10 ppm arsenic, and a solution containing 10 ppm selenium. Then, 0.2 parts by weight of the iron sulfide prepared in Step 1 was added, and the treatment characteristics of heavy metals with iron sulfide were examined. After adding iron sulfide to the model wastewater, the mixture was mixed for 30 minutes, filtered with glass filter paper (GS-25 manufactured by Advantech Toyo), and then the amount of each component contained in the filtrate was measured. The results are shown in Table 6.
[0111]
[Table 6]

As is apparent from the results in Table 6, the iron sulfide in the present invention can also treat heavy metals in waste water.
[0112]
【The invention's effect】
The present invention has the following effects.
1) The iron sulfide of the present invention has a makinawite structure with a novel composition that has not been known so far, and has excellent treatment characteristics for heavy metals and also has excellent durability.
2) The production method of the present invention can easily produce this excellent iron sulfide.
3) The heavy metal treatment agent of the present invention contains this excellent iron sulfide as an active ingredient, and by using this treatment agent, heavy metals contained in ash, soil, waste water, etc. can be treated and rendered harmless. .
[Brief description of the drawings]
FIG. 1 shows the results of X-ray diffraction after iron sulfide powder prepared in Example 1 and its durability treatment at 70 ° C. and 70% relative humidity for 1 day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
2 shows the results of X-ray diffraction of the iron sulfide powders prepared in Example 1, Example 2, and Example 3. FIG. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
FIG. 3 shows the results of X-ray diffraction after iron sulfide powder prepared in Comparative Example 1 was subjected to a one-day durability treatment at 70 ° C. and a relative humidity of 70%. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
FIG. 4 shows the result of X-ray diffraction after iron sulfide powder prepared in Comparative Example 3 was subjected to a one-day durability treatment at 70 ° C. and a relative humidity of 70%. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
FIG. 5 shows the results of X-ray diffraction after iron sulfide powder prepared in Example 5 and its one-day durability treatment at 70 ° C. and a relative humidity of 70%. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
FIG. 6 shows the result of X-ray diffraction after iron sulfide powder prepared in Example 8 was subjected to a one-day durability treatment at 70 ° C. and a relative humidity of 70%. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
7 shows the iron sulfide powder prepared in Example 9 and the results of X-ray diffraction after it was subjected to endurance treatment at 70 ° C. and a relative humidity of 70% for 1 day. FIG. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
8 shows the results of X-ray diffraction of the iron sulfide powders prepared in Example 8, Example 12, Example 13, Example 14, and Example 15. FIG. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the intensity of X-rays (unit is cps).
[Explanation of symbols]
1: X-ray diffraction pattern of the iron sulfide powder prepared in Example 1
2: X-ray diffraction pattern after endurance treatment of the iron sulfide powder prepared in Example 1
3: X-ray diffraction pattern of the iron sulfide powder prepared in Example 1
4: X-ray diffraction pattern of the iron sulfide powder prepared in Example 2
5: X-ray diffraction pattern of the iron sulfide powder prepared in Example 3
6: X-ray diffraction pattern of the iron sulfide powder prepared in Comparative Example 1
7: X-ray diffraction pattern after endurance treatment of the iron sulfide powder prepared in Comparative Example 1
8: X-ray diffraction pattern of the iron sulfide powder prepared in Comparative Example 3
9: X-ray diffraction pattern after endurance treatment of the iron sulfide powder prepared in Comparative Example 3
10: X-ray diffraction pattern of the iron sulfide powder prepared in Example 5
11: X-ray diffraction pattern after endurance treatment of the iron sulfide powder prepared in Example 5
12: X-ray diffraction pattern of the iron sulfide powder prepared in Example 8
13: X-ray diffraction pattern after endurance treatment of the iron sulfide powder prepared in Example 8
14: X-ray diffraction pattern of the iron sulfide powder prepared in Example 9
15: X-ray diffraction pattern after endurance treatment of the iron sulfide powder prepared in Example 9
16: X-ray diffraction pattern of the iron sulfide powder prepared in Example 14
17: X-ray diffraction pattern of the iron sulfide powder prepared in Example 13
18: X-ray diffraction pattern of the iron sulfide powder prepared in Example 12
19: X-ray diffraction pattern of the iron sulfide powder prepared in Example 8
20: X-ray diffraction pattern of the iron sulfide powder prepared in Example 15

Claims (16)

As essential components of the constituent elements, Fe · M _x · N _y · S _z (wherein M is an alkaline earth metal, N is an alkali metal, x, y and z are molar ratios, and 0.01 <x ≦ 0.5, y ≦ 0.2, 0.7 ≦ z ≦ 1.4.) Iron sulfide excellent in durability having a makinawite structure represented by: 2. The machinaite structure according to claim 1, wherein the XRD diffraction pattern has a 001 plane spacing of 5.03 mm to 5.53 mm in the c-axis direction, and the peak intensity from the 001 plane is 100. An iron sulfide excellent in durability having a modified makinawite structure in which the intensity ratio of diffraction peaks from the hkl plane is 20 or less. The aqueous solution of a divalent iron salt, an aqueous solution containing sulfur ions, and an alkaline earth metal component are mixed, and the slurry pH after mixing is 7.0 or more. Production method. The method for producing iron sulfide according to claim 3, wherein the alkaline earth metal is calcium (Ca) and / or magnesium (Mg). A slurry is produced by mixing an aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions in the presence of an alkaline earth metal component, and the slurry pH after mixing is 7.0 or more. The manufacturing method of the iron sulfide of Claim 2. 6. The method for producing iron sulfide according to claim 5, wherein the alkaline earth metal is calcium (Ca) and / or magnesium (Mg). An iron sulfide composition comprising 0.1 to 100 parts by weight of an alkaline earth metal compound with respect to 100 parts by weight of the iron sulfide according to claim 1 or 2. The iron sulfide composition according to claim 7, wherein the alkaline earth metal compound is one or more compounds selected from the group consisting of hydroxides, carboxylates, phosphates and sulfites of alkaline earth metals. The heavy metal processing agent which uses the iron sulfide of Claim 1 or Claim 2 as an active ingredient. The heavy metal processing agent which uses the iron sulfide composition of Claim 7 or Claim 8 as an active ingredient. A detoxification treatment method comprising adding the heavy metal treating agent according to claim 9 or 10 to any one of incineration ash, fly ash, and molten fly ash containing heavy metals, and kneading. The detoxification treatment method according to claim 11, wherein water is further added to the heavy metal treatment agent and kneading. A detoxification treatment method comprising adding the heavy metal treatment agent according to claim 9 or 10 to a soil containing heavy metals and kneading. 14. The detoxification treatment method according to claim 13, wherein water is further added to the heavy metal treatment agent and kneading is performed. A detoxification treatment method comprising adding and mixing the heavy metal treatment agent according to claim 9 or 10 to wastewater containing heavy metals. The harmless metal according to any one of claims 11 to 15, wherein the heavy metal is one or more elements selected from the group consisting of Pb, Cd, Hg, Zn, Cu, Ni, Cr, As, Se, Sb and Mo. Processing method.

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