JP3847531B2

JP3847531B2 - Steelmaking slag aggregate processing method

Info

Publication number: JP3847531B2
Application number: JP2000194609A
Authority: JP
Inventors: 賢一片山; 哲也松下; 幹雄原田
Original assignee: Nisshin Steel Co Ltd; Nippon Magnetic Dressing Co
Current assignee: Nippon Steel Nisshin Co Ltd; Nippon Magnetic Dressing Co
Priority date: 2000-06-28
Filing date: 2000-06-28
Publication date: 2006-11-22
Anticipated expiration: 2020-06-28
Also published as: JP2002020145A

Description

【０００１】
【発明の属する技術分野】
本発明は、製鋼工程で発生するスラグを用いて砂等の天然骨材の代替え材として利用可能な造粒物を製造するための骨材化処理方法に関する。
【０００２】
【従来の技術】
従来、火力発電所等で発生する石炭灰の有効利用方法として、例えば特開平３−２５２３７５号公報に開示されているように、石炭灰を主体としこれにセメントやスラグ等を加えて調合した配合物を水と共に混練し造粒してコンクリート構造物用の透水性骨材として利用する方法が提案されている。一方、製鋼工程で発生する細かい粉状のスラグは、その一部がセメント原料や土壌改良材として有効利用されているが、大部分は有効利用されないまま放置されたり、産業廃棄物として処分されている。そこで、製鋼工程で発生するスラグの有効利用の一環として、石炭灰の代わりにスラグを使用し、これにセメント系の固化材を加えて造粒物を作製し、コンクリートブロック用の骨材として利用することが試みられるようになった。
【０００３】
【発明が解決しようとする課題】
しかしながら、製鋼工程で発生したスラグ中にはＣａＯ、ＭｇＯ等の水と反応して水和物を生成する化合物が存在するため、このスラグにセメント系固化材を加えて造粒した造粒物では、時間の経過と共に周囲に存在する水が造粒物中に侵入し、造粒物内部でＣａＯ、ＭｇＯ等の化合物と徐々に反応して水和物を生成する。造粒物中で水和物が形成されると、体積が増加するため造粒物は膨張を起こし、造粒物内の強度の弱い部分に亀裂が発生して最終的には崩壊する。また、得られた造粒物の強度は砂等の天然骨材に比較して劣るという問題もある。このため、スラグにセメント系の固化材を加え造粒して得られる造粒物を砂等の天然骨材の代替え材として利用することは困難で、製鋼工程で発生するスラグの大部分は製鋼工場内に堆積し、その維持管理、あるいは産業廃棄物としての処分に多大な費用が発生している。
本発明はかかる事情に鑑みてなされたもので、砂等の天然骨材の代替え材として利用可能な造粒物を製鋼工程で発生したスラグを用いて製造する製鋼スラグの骨材化処理方法を提供することを目的とする。
【０００４】
【課題を解決するための手段】
前記目的に沿う第１の発明に係る製鋼スラグの骨材化処理方法は、製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物を調整する第１工程と、前記配合物に造粒に必要な水を加えて造粒物を得る第２工程と、前記造粒物を常温で養生する第３工程とを有し、前記配合物が、前記シリカ源を１０重量％以上で３０重量％以下、前記セメント系固化材を５重量％以上で２０重量％以下、残部を最大粒径が１ｍｍである前記スラグを主体としている。
製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物から造粒物を作製しこの造粒物の養生を行なうとき、ＣａＯ、ＭｇＯ等の化合物、ＳｉＯ₂、及び水が共存する場合では、スラグ中に含まれるＣａＯ、ＭｇＯ等の化合物は単独で水とは反応せず、ＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂及び水の３者の反応が優先し結合性を有する水和硬化物を形成する。このため、ＣａＯ、ＭｇＯ等の化合物と水との水和反応による体積膨張を示す水和物が形成され難く造粒物の崩壊という現象はほとんど発生しない。
【０００５】
前記目的に沿う第２の発明に係る製鋼スラグの骨材化処理方法は、製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物を調整する第１工程と、前記配合物に造粒に必要な水を加えて造粒物を得る第２工程と、前記造粒物を常温で養生する第３工程と、養生後の前記造粒物を高温高圧の水蒸気雰囲気下で水熱処理する第４工程とを有し、前記配合物が、前記シリカ源を１０重量％以上で３０重量％以下、前記セメント系固化材を５重量％以上で２０重量％以下、残部を最大粒径が１ｍｍである前記スラグを主体としている。
ＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂及び水の３者の反応による結合性を有する水和硬化物の生成は、高温高圧の水蒸気雰囲気下で水熱処理することにより促進する。このため、水熱処理により短時間にＣａＯ、ＭｇＯ等の水と反応して水和物を生成するすべての化合物をＳｉＯ₂及び水と反応させて水和硬化物に変化させることが可能となる。造粒物中ではＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂及び水との反応から生成する結合性を有する水和硬化物の形成と、セメント系固化材と水との反応から生成するセメント系水和物の形成とが並行して起こるため、水熱処理により造粒物の強度は大きく向上する。更に、水熱処理後の造粒物にはＣａＯ、ＭｇＯ等の水と反応して水和物を生成する化合物は残留しないので、造粒物に水が侵入しても、体積膨張とそれに伴う造粒物の崩壊という現象は発生せず、化学的に安定な造粒物になっている。
【０００６】
第２の発明に係る製鋼スラグの骨材化処理方法において、前記水熱処理が、温度範囲が１５０℃以上で２５０℃以下、圧力範囲が５ａｔｍ以上で３０ａｔｍ以下、及び処理時間が０．５時間以上で１０時間以下の条件で行なわれることが好ましい。
水熱処理を上記の条件で行なうことにより、製鋼スラグ中のＣａＯ、ＭｇＯ等の水と反応して水和物を生成する化合物をＳｉＯ₂及び水と反応させて効率的に水和硬化物に変化させることが可能となる。
【０００７】
第１又は第２の発明に係る製鋼スラグの骨材化処理方法において、シリカ源を１０重量％以上加えることにより、スラグ中のＣａＯ、ＭｇＯ等の水と反応して水和物が生成する化合物をＳｉＯ₂及び水と反応させてすべて水和硬化物に変化させることができ、水に対する化学的安定性を保証することができる。また、シリカ源が３０重量％を超えて加えられると造粒物の強度が徐々に低下してくる。このため、シリカ源を１０重量％以上で３０重量％以下と規定した。
セメント系固化材を５重量％以上含むように調整することにより、造粒物に強度を発現させて取り扱いを容易にすることができる。また、造粒物が必要とする強度、例えば天然砂並みの強度を得るには、セメント系固化材の使用量は高々２０重量％で十分である。このため、セメント系固化材を５重量％以上２０重量％以下と規定した。
更に、スラグの最大粒径を１ｍｍとすることにより、造粒物の均質性を高めることができ、品質の安定した造粒物を得ることができる。
【０００８】
【発明の実施の形態】
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
ここに、図１は本発明の第１の実施の形態に係る製鋼スラグの骨材化処理方法の説明図、図２は第２の実施の形態に係る製鋼スラグの骨材化処理方法の説明図である。
本発明の第１の実施の形態に係る製鋼スラグの骨材化処理方法は、製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物を調整する第１工程と、配合物に造粒に必要な水を加えて造粒物を作製する第２工程と、造粒物を常温で養生する第３工程とを有する（以下、造粒方式と呼ぶ）。以下、各工程毎に更に詳しく説明する。
【０００９】
（１）第１工程
例えば、図１に示すように、混合機と造粒機の機能を備えた混合撹拌式造粒機の一例である容量が５リットルのアイリッヒミキサーに、ＳｉＯ₂を主成分とするシリカ源の一例である石炭灰が１０重量％以上で３０重量％以下、セメント系固化材の一例である普通ポルトランドセメントが５重量％以上で２０重量％以下、残部が最大粒径１ｍｍであるスラグとなるように各粉体を秤量して投入し、パンを３０〜５０ｒｐｍの回転数で回転すると共に、アジテーターを３０００〜４０００ｒｐｍの回転数で３〜５分間撹拌混合して均一な配合物を作製する。ここで、アイリッヒミキサーに投入する粉体の容量はアイリッヒミキサーの容量の２０〜１００％の範囲とする。容量の２０％未満、あるいは１００％を超えて粉体を投入すると、撹拌混合して均一な配合物を作製するのに非常に長時間を要し、更に、次工程の造粒物の製造歩留りが低下する。
【００１０】
（２）第２工程
撹拌混合して均一な配合物が得られた時点で、水を配合物の重量に対して、例えば、１５重量％以上で２５重量％以下の範囲となるように加えて、水が配合物に均一に分散するまで撹拌混合を続ける。次いで、パンの回転数は変化させずにアジテーターの回転数を１６００〜２０００ｒｐｍの回転数に低下させ造粒操作を開始する。造粒操作を開始すると、当初粉末状であった配合物中に微細粒が発生し、時間の経過と共にこの微細粒は周囲に存在する粉末を吸着して粒径を徐々に成長させていく。造粒を開始してから４〜６分間程度で全体が、例えば、中心粒径が２〜４ｍｍ程度の造粒物に変化する。この時点で、アジテーターの回転を停止して、造粒操作を終了する。次いで、パンを回転させた状態で、アイリッヒミキサーの排出口を開けて造粒物を容器内に落下させて回収する。
【００１１】
（３）第３工程
回収した造粒物を常温で、例えば、２０〜１００日程度屋内で養生する。養生中に造粒物中でセメント水和物の生成が進行する。また、養生中にＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂及び水の３者が反応して結合性を有する水和硬化物の生成が進行する。このため、養生後の造粒物の強度は向上し、造粒物内にはＣａＯ、ＭｇＯ等の水と反応して水和物が生成する化合物がほとんど残留していない状態となっている。
なお、養生後の造粒物中にはＣａＯ、ＭｇＯ等の化合物が単独で水と反応するのを抑制するだけの十分な量のＳｉＯ₂は残留していないため、造粒物中に水が侵入すると残留しているＣａＯ、ＭｇＯ等の化合物と水との反応が生じるが、残留しているＣａＯ、ＭｇＯ等の化合物の量が少ないため生成する水和物の量が少なく、造粒物の膨張とそれに伴う造粒物の崩壊という現象はほとんど発生しないようになる。
【００１２】
本発明の第２の実施の形態に係る製鋼スラグの骨材化処理方法は、製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物を調整する第１工程と、配合物に造粒に必要な水を加えて造粒物を得る第２工程と、造粒物を常温で養生する第３工程と、養生後の造粒物を高温高圧の水蒸気雰囲気下で水熱処理する第４工程とを有する（以下、水熱処理方式と呼ぶ）。ここで、図２に示すように、第１工程と第２工程は第１の実施の形態と内容が同一であるので、第３工程と第４工程について更に詳しく説明する。
【００１３】
（１）第３工程
回収した造粒物を常温で、例えば、１日〜４０日程度屋内で養生して、造粒物の強度を向上させる。第３工程で行なう養生は、引き続いて行なう第４工程の操作の際に造粒物が破損しないように造粒物に強度を付与することが主目的である。このため、第４工程の操作の際に造粒物が破損しない強度を造粒物に付与するのであれば、１日程度の短期間の養生を行なうだけで十分である。また、造粒物の強度をより強固にするため４０日程度の長期間の養生を行い、セメント水和物の生成の促進と、スラグ中のＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂及び水との反応より得られる結合性の水和硬化物の生成の促進を図ってもよい。
【００１４】
（２）第４工程
養生後の造粒物を、例えばオートクレーブを使用して、温度１５０〜２５０℃、圧力５〜３０ａｔｍの条件下での水熱処理を０．５〜１０時間行なう。水熱処理の温度が１５０℃未満ではセメント水和物の生成速度及び、ＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂と水の反応による結合性を有する水和硬化物の生成速度が共に低く、長時間の水熱処理を行なわないと造粒物の強度が十分に向上しない。また、２５０℃を超えると生成する水和物の結晶構造が変化して水熱処理後の造粒物の強度は低下してくる。このため、処理温度を１５０以上で２５０℃以下の範囲に規定した。なお、処理温度が１５０〜２５０℃の範囲に規定されると、水蒸気の圧力は５ａｔｍ以上で３０ａｔｍ以下の範囲となる。
処理温度が１５０〜２５０℃、圧力が５〜３０ａｔｍの条件下では、処理時間が０．５時間未満では十分な量の水和物が生成されず造粒物の強度が十分に向上しない。また、処理時間の増加に伴い造粒物の強度はしだいに向上するが、１０時間を超えて処理を行なっても造粒物の強度向上はほぼ飽和して大幅に向上することはない。このため、処理時間を０．５〜１０時間に規定した。
【００１５】
オートクレーブによる水熱処理により、セメント水和物の生成促進、及びＣａＯ、ＭｇＯ等の化合物とＳｉＯ₂と水との反応による結合性を有する水和硬化物の生成促進が並行して達成されるため、セメント系固化材による強度発現と水和硬化物の形成による強度発現との複合効果により、造粒物の強度は大きく向上する。また、水熱処理後の造粒物にはＣａＯ、ＭｇＯ等の水と反応して水和物が生成する化合物は残留しないので、造粒物に水が侵入しても、体積膨張とそれに伴う造粒物の崩壊という現象は発生せず、化学的に安定な造粒物となっている。
【００１６】
【実施例】
１．造粒方式
（１）第１工程
製鋼スラグとしてステンレス鋼製造時に発生し金属成分をほとんど含んでいない最大粒径が０．１５ｍｍのスラグと、シリカ源として火力発電所から発生する石炭灰と、セメント系固化材として市販されている普通ポルトランドセメントを用い、容量が５リットルのアイリッヒミキサーを使用して、表１に記載した５種類の配合割合を有する配合物を各３ｋｇ（アイリッヒミキサー容量の６０％）ずつ作製した。アイリッヒミキサーによる配合物の調整は、パン回転数４０ｒｐｍ、アジテーター回転数３６００ｒｐｍの条件で行い、撹拌混合時間は３分間である。
【００１７】
【表１】

【００１８】
（２）第２工程
アイリッヒミキサーによる配合調整が終了後、パン回転数４０ｒｐｍ、アジテーター回転数３６００ｒｐｍの撹拌混合条件で、配合物の重量に対して２０重量％の水を加えて配合物中に水が均一に分散するまで撹拌混合を続けた。次いで、パンの回転数を変化させずにアジテーターの回転数を１８００ｒｐｍに低下させ、造粒操作を開始する。造粒開始後、５分間で配合物は全体が中心粒径が２〜３ｍｍの造粒物に変化したので、アジテーターの回転を停止して造粒操作を終了した。次いで、パンを回転させた状態で、アイリッヒミキサーの排出口を開けて造粒物を容器内に落下させて回収した。
（３）第３工程
回収した５種類の造粒物をそれぞれ養生用の薄底容器に薄く展開し、３０又は９０日間屋内で養生した。
【００１９】
養生後の６種類の造粒物のそれぞれから、篩分けで粒径が２．８３ｍｍ以上で３．３６ｍｍ未満の範囲の造粒物を１０個抽出し、強度試験機を用いて各造粒物が圧壊する際の最大荷重を測定した。１０個の造粒物を用いて測定された各最大荷重の平均値を求めて、この平均値の値を造粒物の圧壊強度とした。得られた圧壊強度を表１に示す。
また、造粒物の膨張崩壊の程度を調査するため、オートクレーブを用いた加速試験を行なった。養生後の６種類の造粒物から篩分けで粒径が１ｍｍ未満の造粒物を除いたものを加速試験用のサンプルとし、オートクレーブを用いて温度２１５℃、２０ａｔｍの飽和水蒸気雰囲気中に各加速試験用のサンプルを３時間保持する条件で加速試験を行なった。オートクレーブから取り出した造粒物を０．１５ｍｍの篩に通して０．１５ｍｍ以下の造粒物を回収し、その重量から０．１５ｍｍ以下の造粒物の含有率を求めて、この含有率の値をオートクレーブを用いた加速試験での造粒物の崩壊率とした。崩壊率を表１に示す。
表１から、セメントを使用しないと３０日間養生しても造粒物の強度は向上せず、石炭灰を１０重量％未満の配合ではオートクレーブを用いた加速試験で膨張崩壊し易いことが判明し、造粒物の化学的安定性を向上させるには石炭灰を１０重量％以上配合する必要があることが判明した。更に、セメントを１３重量％配合した場合９０日間養生することにより、天然砂並みの強度を有する造粒物が得られることが判った。従って、製鋼スラグに石炭灰とセメントを配合することにより、強度を有して崩壊しにくい造粒物が製造できることが判明した。
【００２０】
２．水熱処理方式
（１）第１工程
ステンレス鋼製造時に発生し金属成分をほとんど含んでいない最大粒径が０．１５ｍｍのスラグと、シリカ源として火力発電所から発生する石炭灰と、セメント系固化材として市販されている普通ポルトランドセメントを用い、容量が５リットルのアイリッヒミキサーを使用して、表２に記載した配合割合を有する配合物を各３ｋｇずつ作製した。アイリッヒミキサーによる配合物の調整は、パン回転数４０ｒｐｍ、アジテーター回転数３６００ｒｐｍの条件で行い、撹拌混合時間は３分間である。
【００２１】
【表２】

【００２２】
（２）第２工程
アイリッヒミキサーによる配合調整が終了後、パン回転数４０ｒｐｍ、アジテーター回転数３６００ｒｐｍの撹拌混合条件で、配合物の重量に対して２０重量％の水を加えて配合物中に水が均一に分散するまで撹拌混合を続けた。次いで、パンの回転数は変化させずにアジテーターの回転数を１８００ｒｐｍに低下させ、造粒操作を開始する。造粒開始後、５分間で配合物は全体が中心粒径が２〜３ｍｍの造粒物に変化したので、アジテーターの回転を停止して造粒操作を終了した。次いで、パンを回転させた状態で、アイリッヒミキサーの排出口を開けて造粒物を容器内に落下させて回収した。
（３）第３工程
回収した造粒物を養生用の薄底容器に薄く展開し、１、７又は３０日間屋内で養生した。
（４）第４工程
養生後の３種類の造粒物をそれぞれオートクレーブを用いて、温度２００℃、１５ａｔｍの飽和水蒸気雰囲気で３時間保持して水熱処理を行なった。
【００２３】
水熱処理後の３種類の造粒物のそれぞれから、篩分けで粒径が２．８３ｍｍ以上で３．３６ｍｍ未満の範囲の造粒物を１０個抽出し、強度試験機を用いて各造粒物が圧壊する際の最大荷重を測定した。１０個の造粒物で用いて測定された各最大荷重の平均値を求めて、この平均値の値を圧壊強度とした。得られた圧壊強度を表２に示す。
また、造粒物の膨張崩壊の程度を調査するため、オートクレーブを用いた加速試験を行なった。養生後の３種類の造粒物から篩分けで粒径が１ｍｍ未満の造粒物を除いたものを加速試験用のサンプルとし、オートクレーブを用いて温度２１５℃、２０ａｔｍの飽和水蒸気雰囲気中に各加速試験用のサンプルを３時間保持する条件で加速試験を行なった。オートクレーブから取り出した造粒物を０．１５ｍｍの篩に通して０．１５ｍｍ以下の造粒物を回収し、その重量から０．１５ｍｍ以下の造粒物の含有率を求めて、この含有率の値をオートクレーブを用いた加速試験での造粒物の崩壊率とした。崩壊率を表２に示す。
【００２４】
表２から、オートクレーブによる水熱処理を行なうことで、天然砂並みの強度を有する造粒物が得られることが判った。また、水熱処理が前提であれば、１日の養生を行なうだけで天然砂並みの強度を有する造粒物が得られ、養生に必要な作業場所の確保が不要になり、狭い場所においても作業が可能となる。更に、水熱処理した造粒物では、オートクレーブを用いた加速試験での崩壊率は０％となっており、水熱処理により天然砂と同等の化学的安定性を有する造粒物が得られることが判明した。
【００２５】
以上、本発明の実施の形態を説明したが、本発明は、この実施の形態に限定されるものではなく、例えば、製鋼スラグとして乾燥状態のスラグを使用したが、湿式処理時の沈澱槽内のスラリーをフィルタープレスにより脱水したケーキを使用することもできる。また、造粒物の養生を屋内で実施したが、温度と湿度を管理した雰囲気中で行なうこともできる。更に、シリカ源として石炭灰を使用したが、シリコン製造時に発生するシリカヒュームも使用できる。セメント系固化材として普通ポルトランドセメントを使用したが、早強ポルトランドセメント、高炉セメント等も使用できる。
【００２６】
【発明の効果】
請求項１記載の製鋼スラグの骨材化処理方法においては、製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物を調整する第１工程と、配合物に造粒に必要な水を加えて造粒物を得る第２工程と、造粒物を常温で養生する第３工程とを有するので、製鋼スラグから天然の山砂、砕石バラス、海砂等の代替え材を安価に製造することができる。このため、製鋼工程で発生する粉粒状スラグの廃棄処分や工場内での保管業務が削減でき、環境保護に貢献できると共に、工場内でのスラグ処分のコストの削減に寄与することができる。
【００２７】
請求項２及びこれに従属する請求項３記載の製鋼スラグの骨材化処理方法においては、製鋼工程で発生するスラグと、ＳｉＯ₂を主成分とするシリカ源と、セメント系固化材とを主体とする配合物を調整する第１工程と、配合物に造粒に必要な水を加えて造粒物を得る第２工程と、造粒物を常温で養生する第３工程と、養生後の造粒物を高温高圧の水蒸気雰囲気下で水熱処理する第４工程とを有するので、製鋼スラグから天然の山砂、砕石バラス、海砂等と品質が同等か又はそれ以上の品質を有する代替え材を容易に得ることができる。このため、製鋼工程で発生する粉粒状スラグの再利用を促進することができる。
【００２８】
特に、請求項３記載の製鋼スラグの骨材化処理方法においては、水熱処理が、温度範囲が１５０℃以上で２５０℃以下、圧力範囲が５ａｔｍ以上で３０ａｔｍ以下、及び処理時間が０．５時間以上で１０時間以下の条件で行なわれるので、天然の山砂、砕石バラス、海砂等と品質が同等か又はそれ以上の品質を有する代替え材を効率的に製造することができる。
そして、請求項１、２記載の製鋼スラグの骨材化処理方法においては、配合物が、シリカ源を１０重量％以上で３０重量％以下、セメント系固化材を５重量％以上で２０重量％以下、残部を最大粒径が１ｍｍであるスラグを主体としているので、安価な原料を用いて天然の山砂、砕石バラス、海砂等の代替え材を得ることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る製鋼スラグの骨材化処理方法の説明図である。
【図２】本発明の第２の実施の形態に係る製鋼スラグの骨材化処理方法の説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aggregate processing method for producing a granulated material that can be used as a substitute for natural aggregates such as sand, using slag generated in a steelmaking process.
[0002]
[Prior art]
Conventionally, as an effective utilization method of coal ash generated in a thermal power plant or the like, for example, as disclosed in Japanese Patent Laid-Open No. 3-252375, a blend of coal ash as a main component and added with cement, slag, etc. A method has been proposed in which an object is kneaded with water and granulated to be used as a water-permeable aggregate for a concrete structure. On the other hand, the fine powdery slag generated in the steelmaking process is partly used effectively as a raw material for cement and soil improvement, but most of it is left unused or disposed as industrial waste. Yes. Therefore, as part of the effective use of slag generated in the steelmaking process, slag is used instead of coal ash, and a cement-based solidifying material is added to this to produce a granulated product, which is used as an aggregate for concrete blocks. Attempted to do so.
[0003]
[Problems to be solved by the invention]
However, in the slag generated in the steel making process, there are compounds that react with water such as CaO and MgO to produce hydrates. The water existing in the surroundings enters the granulated product with the passage of time, and gradually reacts with a compound such as CaO or MgO to produce a hydrate inside the granulated product. When a hydrate is formed in the granulated product, the volume increases and the granulated product expands, cracks are generated in a weak portion in the granulated product, and eventually collapses. There is also a problem that the strength of the obtained granulated product is inferior to that of natural aggregate such as sand. For this reason, it is difficult to use a granulated product obtained by adding cement-based solidification material to slag and granulating it as a substitute for natural aggregates such as sand. Most of the slag generated in the steelmaking process is steelmaking. Accumulated in the factory, the maintenance and management, or disposal as industrial waste, has a great expense.
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides an aggregate processing method for steelmaking slag in which a granulated material that can be used as a substitute for natural aggregate such as sand is produced using slag generated in the steelmaking process. The purpose is to provide.
[0004]
[Means for Solving the Problems]
Aggregate processing method steelmaking slag according to the first invention along the object, the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, formulations mainly a cement solidifying material possess a first step of adjusting, and a second step of obtaining a granulated product by the addition of water required for the granulation to the formulations, and a third step of curing the granulated product at ambient temperature, said formulation things, the silica source 30 wt% 10 wt% inclusive, the cementitious solidifying material in 5 wt% to 20 wt% or less, a maximum particle size of the balance it is mainly of the slag is 1 mm.
When performing the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, to prepare a granulated product from a formulation consisting mainly of a cement solidifying material to curing of the granules, CaO, MgO When compounds such as SiO ₂ and water coexist, compounds such as CaO and MgO contained in the slag do not react with water alone, but compounds such as CaO and MgO, SiO ₂ and water This reaction preferentially forms a hydrated cured product having binding properties. For this reason, it is difficult to form a hydrate exhibiting volume expansion due to a hydration reaction between a compound such as CaO or MgO and water, and the phenomenon of collapse of the granulated material hardly occurs.
[0005]
Aggregate processing method steelmaking slag according to the second invention along the object, the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, formulations mainly a cement solidifying material A first step of adjusting the composition, a second step of adding water necessary for granulation to the blend to obtain a granulated product, a third step of curing the granulated product at room temperature, and the granulation after curing have a fourth step of hydrothermal treatment the particle material in a water vapor atmosphere of high temperature and high pressure, the formulation, the silica source 30 wt% 10 wt% inclusive, the cement-based solidifying material 5 wt% or more in 20 wt% or less, a maximum particle size of the balance it is mainly of the slag is 1 mm.
Formation of a hydrated cured product having binding properties by the reaction of a compound such as CaO and MgO with SiO ₂ and water is promoted by hydrothermal treatment in a high-temperature and high-pressure steam atmosphere. Therefore, all the compounds that react with water such as CaO and MgO in a short time by hydrothermal treatment to form hydrates can be reacted with SiO ₂ and water to be converted into hydrated cured products. In the granulated product, formation of a hydrated cured product having a binding property generated from a reaction between a compound such as CaO and MgO, SiO ₂ and water, and a cement-based hydration generated from a reaction between a cement-based solidifying material and water. Since the formation of the product occurs in parallel, the strength of the granulated product is greatly improved by the hydrothermal treatment. Furthermore, since the granulated product after hydrothermal treatment does not retain a compound that reacts with water such as CaO or MgO to form a hydrate, even if water enters the granulated product, volume expansion and accompanying granulation are caused. The phenomenon of particle disintegration does not occur, and it is a chemically stable granulated product.
[0006]
In the aggregate processing method for steelmaking slag according to the second invention, the hydrothermal treatment is performed at a temperature range of 150 ° C. or more and 250 ° C. or less, a pressure range of 5 atm or more and 30 atm or less, and a treatment time of 0.5 hour or more. It is preferably carried out under the conditions of 10 hours or less.
By performing hydrothermal treatment under the above conditions, the compound that reacts with water such as CaO and MgO in steelmaking slag reacts with SiO ₂ and water to efficiently convert to a hydrated cured product. It becomes possible to make it.
[0007]
In the method for assembling steelmaking slag according to the first or second invention, a compound that reacts with water such as CaO and MgO in the slag to form a hydrate by adding 10% by weight or more of a silica source. Can be converted into a hydrated cured product by reacting with SiO ₂ and water, and chemical stability against water can be ensured. Further, when the silica source is added in an amount exceeding 30% by weight, the strength of the granulated product gradually decreases. For this reason, the silica source was defined as 10 wt% or more and 30 wt% or less.
By adjusting the cement-based solidified material so as to contain 5% by weight or more, the granulated product can be made strong and easy to handle. Further, in order to obtain the strength required for the granulated product, for example, the strength equivalent to that of natural sand, the use amount of the cement-based solidified material is 20% by weight at most. For this reason, the cement-based solidified material is defined as 5% by weight or more and 20% by weight or less.
Furthermore, by setting the maximum particle size of the slag to 1 mm, the homogeneity of the granulated product can be increased, and a granulated product with stable quality can be obtained.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory view of an aggregate processing method for steelmaking slag according to the first embodiment of the present invention, and FIG. 2 is an explanatory view of an aggregate processing method for steelmaking slag according to the second embodiment. FIG.
Aggregate processing method steelmaking slag according to the first embodiment of the present invention is formulated to the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, mainly a cement solidifying material A first step of adjusting the product, a second step of adding water necessary for granulation to the blend to produce a granulated product, and a third step of curing the granulated product at room temperature (hereinafter referred to as granulation). Called the grain method). Hereinafter, it demonstrates in detail for every process.
[0009]
(1) First step For example, as shown in FIG. 1, SiO ₂ is mainly added to an Eirich mixer with a capacity of 5 liters which is an example of a mixing and stirring granulator having the functions of a mixer and a granulator. Coal ash, which is an example of a silica source as a component, is 10% by weight to 30% by weight, normal Portland cement, which is an example of a cement-based solidified material, is 5% by weight to 20% by weight, and the remainder is a maximum particle size of 1 mm. Each powder is weighed and added to form a slag, and the pan is rotated at a rotation speed of 30 to 50 rpm, and the agitator is stirred and mixed at a rotation speed of 3000 to 4000 rpm for 3 to 5 minutes to uniformly mix. Make a thing. Here, the volume of the powder charged into the Eirich mixer is in the range of 20 to 100% of the volume of the Eirich mixer. When the powder is added to less than 20% or more than 100% of the capacity, it takes a very long time to produce a uniform blend by stirring and mixing, and further, the production yield of the granulated product in the next step Decreases.
[0010]
(2) At the time when the second step is stirred and mixed to obtain a uniform blend, water is added to the blend, for example, in a range of 15 wt% to 25 wt%. Continue stirring and mixing until water is uniformly dispersed in the formulation. Next, without changing the rotation speed of the pan, the rotation speed of the agitator is decreased to 16000 to 2000 rpm and the granulation operation is started. When the granulation operation is started, fine particles are generated in the initially powdered formulation, and with the passage of time, the fine particles adsorb the surrounding powder and gradually grow the particle size. The whole changes to a granulated product having a center particle size of about 2 to 4 mm in about 4 to 6 minutes after the start of granulation. At this point, the rotation of the agitator is stopped and the granulation operation is completed. Next, with the pan rotated, the outlet of the Eirich mixer is opened and the granulated material is dropped into the container and collected.
[0011]
(3) The granulated product recovered in the third step is cured at room temperature, for example, for about 20 to 100 days indoors. Cement hydrate formation proceeds in the granulate during curing. Further, during curing, a compound such as CaO, MgO, SiO ₂ and water react to generate a hydrated cured product having binding properties. For this reason, the strength of the granulated product after curing is improved, and in the granulated product, a compound that reacts with water such as CaO and MgO to form a hydrate is hardly left.
In addition, since there is no sufficient amount of SiO ₂ remaining in the granulated product after curing to prevent a compound such as CaO and MgO from reacting with water alone, water is not present in the granulated product. Intrusion causes a reaction between the remaining compounds such as CaO and MgO and water, but since the amount of the remaining compounds such as CaO and MgO is small, the amount of hydrate produced is small, The phenomenon of expansion and the collapse of the granulated material accompanying it hardly occurs.
[0012]
Aggregate processing method steelmaking slag according to the second embodiment of the present invention is formulated to the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, mainly a cement solidifying material A first step of adjusting the product, a second step of adding water necessary for granulation to the blend to obtain a granulated product, a third step of curing the granulated product at room temperature, and a granulated product after curing And a fourth step of hydrothermally treating in a steam atmosphere of high temperature and high pressure (hereinafter referred to as hydrothermal treatment method). Here, as shown in FIG. 2, the contents of the first process and the second process are the same as those of the first embodiment, and therefore the third process and the fourth process will be described in more detail.
[0013]
(1) The granulated product recovered in the third step is cured at room temperature, for example, indoors for about 1 to 40 days to improve the strength of the granulated product. The main purpose of the curing performed in the third step is to impart strength to the granulated product so that the granulated product is not damaged during the subsequent operation of the fourth step. For this reason, it is sufficient to perform the curing for a short period of time of about one day if the granulated product is given a strength that does not damage the granulated product during the operation of the fourth step. Moreover, in order to strengthen the strength of the granulated material, curing is carried out for a long period of about 40 days, the formation of cement hydrate is promoted, and the compounds such as CaO and MgO in slag, SiO ₂ and water The generation of a binding hydrated cured product obtained from the reaction may be promoted.
[0014]
(2) The granulated product after the fourth step curing is subjected to hydrothermal treatment for 0.5 to 10 hours under conditions of a temperature of 150 to 250 ° C. and a pressure of 5 to 30 atm using, for example, an autoclave. When the hydrothermal treatment temperature is less than 150 ° C., the rate of formation of cement hydrate and the rate of formation of hydrated cured products having binding properties due to the reaction of compounds such as CaO, MgO and SiO ₂ with water are both low and prolonged. If the hydrothermal treatment is not performed, the strength of the granulated product will not be sufficiently improved. Moreover, when it exceeds 250 degreeC, the crystal structure of the hydrate to produce | generate will change, and the intensity | strength of the granulated material after a hydrothermal treatment will fall. For this reason, the processing temperature was specified in the range of 150 to 250 ° C. In addition, when process temperature is prescribed | regulated in the range of 150-250 degreeC, the pressure of water vapor | steam will be the range of 5 atm or more and 30 atm or less.
Under the conditions of a treatment temperature of 150 to 250 ° C. and a pressure of 5 to 30 atm, if the treatment time is less than 0.5 hours, a sufficient amount of hydrate is not generated and the strength of the granulated product is not sufficiently improved. Moreover, although the intensity | strength of a granulated material improves gradually with the increase in processing time, even if it processes over 10 hours, the strength improvement of a granulated material will be substantially saturated and will not improve significantly. For this reason, processing time was prescribed | regulated to 0.5 to 10 hours.
[0015]
By hydrothermal treatment with an autoclave, the formation promotion of cement hydrates and the formation promotion of hydrated cured products having binding properties due to the reaction between compounds such as CaO and MgO and SiO ₂ and water are achieved in parallel. The strength of the granulated product is greatly improved by the combined effect of the strength development by the cement-based solidified material and the strength development by the formation of the hydrated cured product. In addition, since the granulated product after hydrothermal treatment does not retain a compound that forms a hydrate by reacting with water such as CaO or MgO, even if water enters the granulated product, volume expansion and accompanying granulation are caused. The phenomenon of particle collapse does not occur, and it is a chemically stable granulated product.
[0016]
【Example】
1. Granulation method (1) The first step steelmaking slag, which is produced during the production of stainless steel, has a maximum particle size of 0.15 mm and contains almost no metal components, coal ash generated from a thermal power plant as a silica source, and cement Using ordinary Portland cement marketed as a system solidifying material and using an Eirich mixer with a capacity of 5 liters, 3 kg each of the blends having the 5 blending ratios shown in Table 1 (of Eirich mixer capacity) 60%). Adjustment of the formulation by an Eirich mixer is performed under the conditions of a bread rotation speed of 40 rpm and an agitator rotation speed of 3600 rpm, and the stirring and mixing time is 3 minutes.
[0017]
[Table 1]

[0018]
(2) Second Step After the blending adjustment by the Eirich mixer is completed, 20% by weight of water is added to the weight of the blend under stirring and mixing conditions of a pan rotation speed of 40 rpm and an agitator rotation speed of 3600 rpm. Stir mixing was continued until the water was evenly dispersed. Next, without changing the rotation speed of the bread, the rotation speed of the agitator is reduced to 1800 rpm, and the granulation operation is started. In 5 minutes after the start of granulation, the entire composition changed to a granulated product having a center particle diameter of 2 to 3 mm, so the rotation of the agitator was stopped and the granulation operation was completed. Next, with the pan rotated, the outlet of the Eirich mixer was opened and the granulated material was dropped into the container and collected.
(3) The 5 types of granulated materials collected in the third step were each thinly spread in a thin bottom container for curing and cured indoors for 30 or 90 days.
[0019]
From each of the six types of granules after curing, 10 granules with a particle size of 2.83 mm or more and less than 3.36 mm are extracted by sieving, and each granulated product is tested using a strength tester. The maximum load when crushing was measured. The average value of each maximum load measured using 10 granulated materials was obtained, and the value of this average value was used as the crushing strength of the granulated material. The obtained crushing strength is shown in Table 1.
In addition, an acceleration test using an autoclave was performed to investigate the degree of expansion and collapse of the granulated product. Samples obtained by sieving from the six types of granulated products after sieving and removing the granulated product having a particle size of less than 1 mm are used as samples for an acceleration test. Each sample is placed in a saturated steam atmosphere at a temperature of 215 ° C. and 20 atm using an autoclave. The acceleration test was performed under the condition that the sample for the acceleration test was held for 3 hours. The granulated product taken out from the autoclave is passed through a 0.15 mm sieve to recover a granulated product of 0.15 mm or less, and the content of the granulated product of 0.15 mm or less is determined from its weight. The value was taken as the disintegration rate of the granulated product in the acceleration test using an autoclave. The decay rate is shown in Table 1.
From Table 1, it was found that if cement is not used, the strength of the granulated material does not improve even after curing for 30 days, and if it contains less than 10% by weight of coal ash, it tends to expand and collapse in an accelerated test using an autoclave. In order to improve the chemical stability of the granulated product, it has been found that it is necessary to add 10% by weight or more of coal ash. Further, it was found that a granulated product having a strength similar to that of natural sand can be obtained by curing for 90 days when 13% by weight of cement is blended. Therefore, it has been found that by adding coal ash and cement to steelmaking slag, it is possible to produce a granulated product that has strength and is difficult to disintegrate.
[0020]
2. Hydrothermal treatment method (1) First step Slag generated at the time of stainless steel production and having a maximum particle size of 0.15 mm, coal ash generated from a thermal power plant as a silica source, and cement-based solidified material 3 kg each of the blends having the blending ratios shown in Table 2 were prepared using a normal Portland cement commercially available as an Erich mixer with a capacity of 5 liters. Adjustment of the formulation by an Eirich mixer is performed under the conditions of a bread rotation speed of 40 rpm and an agitator rotation speed of 3600 rpm, and the stirring and mixing time is 3 minutes.
[0021]
[Table 2]

[0022]
(2) Second Step After the blending adjustment by the Eirich mixer is completed, 20% by weight of water is added to the weight of the blend under stirring and mixing conditions of a pan rotation speed of 40 rpm and an agitator rotation speed of 3600 rpm. Stir mixing was continued until the water was evenly dispersed. Next, the rotational speed of the agitator is reduced to 1800 rpm without changing the rotational speed of the pan, and the granulation operation is started. In 5 minutes after the start of granulation, the entire composition changed to a granulated product having a center particle diameter of 2 to 3 mm, so the rotation of the agitator was stopped and the granulation operation was completed. Next, with the pan rotated, the outlet of the Eirich mixer was opened and the granulated material was dropped into the container and collected.
(3) The granulated product collected in the third step was thinly spread in a thin-bottom container for curing and cured indoors for 1, 7 or 30 days.
(4) The three types of granules after curing in the fourth step were each hydrothermally treated using an autoclave and held in a saturated steam atmosphere at a temperature of 200 ° C. and 15 atm for 3 hours.
[0023]
From each of the three types of granulated product after hydrothermal treatment, 10 granulated products having a particle size of 2.83 mm or more and less than 3.36 mm are extracted by sieving, and each granulated product is tested using a strength tester. The maximum load when the object collapses was measured. The average value of each maximum load measured by using 10 granulated products was obtained, and the value of this average value was taken as the crushing strength. The obtained crushing strength is shown in Table 2.
In addition, an acceleration test using an autoclave was performed to investigate the degree of expansion and collapse of the granulated product. Samples obtained by sieving from the three types of granulated products after sieving and excluding the granulated products having a particle size of less than 1 mm are used as samples for an accelerated test. Each sample is placed in a saturated steam atmosphere at a temperature of 215 ° C and 20 atm using an autoclave. The acceleration test was performed under the condition that the sample for the acceleration test was held for 3 hours. The granulated product taken out from the autoclave is passed through a 0.15 mm sieve to recover a granulated product of 0.15 mm or less, and the content of the granulated product of 0.15 mm or less is determined from its weight. The value was taken as the disintegration rate of the granulated product in the acceleration test using an autoclave. The decay rate is shown in Table 2.
[0024]
From Table 2, it was found that a granulated product having the same strength as natural sand can be obtained by hydrothermal treatment with an autoclave. Also, if hydrothermal treatment is premised, a granulated product with the same strength as natural sand can be obtained just by curing for one day, making it unnecessary to secure a working place necessary for curing, and working in a narrow place. Is possible. Furthermore, the granulated product subjected to hydrothermal treatment has a disintegration rate of 0% in an accelerated test using an autoclave, and a granulated product having chemical stability equivalent to natural sand can be obtained by hydrothermal treatment. found.
[0025]
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, For example, although the slag of the dry state was used as steelmaking slag, in the precipitation tank at the time of wet processing It is also possible to use a cake obtained by dehydrating a slurry of the above by a filter press. Moreover, although the granulation was cured indoors, it can also be performed in an atmosphere in which temperature and humidity are controlled. Further, although coal ash is used as a silica source, silica fume generated during silicon production can also be used. Ordinary Portland cement was used as the cement-based solidifying material, but early-strength Portland cement, blast furnace cement, and the like can also be used.
[0026]
【The invention's effect】
In aggregate processing method steel slag according to claim 1, the adjusting the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, the formulation composed mainly of a cement solidifying material Since it has one step, a second step of adding water necessary for granulation to the blend to obtain a granulated product, and a third step of curing the granulated product at room temperature, natural steel sand from steelmaking slag, Alternative materials such as crushed stone ballast and sea sand can be produced at low cost. For this reason, the disposal of the granular slag generated in the steelmaking process and the storage work in the factory can be reduced, which can contribute to environmental protection and can contribute to the reduction of the cost of the slag disposal in the factory.
[0027]
Mainly in claims 2 and aggregate processing method steel slag according to claim 3, wherein the subordinate thereto, the slag generated in the steel making process, and the silica source consisting primarily of SiO _2, and a cement solidifying material A first step of adjusting the blend, a second step of adding water necessary for granulation to the blend to obtain a granulated product, a third step of curing the granulated product at room temperature, and a post-curing step 4th step of hydrothermally treating the granulated material in a high-temperature and high-pressure steam atmosphere, so that the substitute material has the same or better quality than steel pile slag, natural mountain sand, crushed stone ballast, sea sand, etc. Can be easily obtained. For this reason, the reuse of the granular slag generated in the steel making process can be promoted.
[0028]
In particular, in the method of assembling the steelmaking slag according to claim 3, the hydrothermal treatment is performed at a temperature range of 150 ° C. to 250 ° C., a pressure range of 5 atm to 30 atm, and a treatment time of 0.5 hours. Since the process is performed for 10 hours or less as described above, a substitute material having a quality equivalent to or higher than that of natural mountain sand, crushed stone ballast, sea sand, or the like can be efficiently produced.
In the method of assembling the steelmaking slag according to claims 1 and 2 , the composition comprises 10% by weight or more and 30% by weight or less of the silica source, and 5% by weight or more and 20% by weight of the cement-based solidified material. Hereinafter, since the remainder is mainly slag having a maximum particle size of 1 mm, substitute materials such as natural mountain sand, crushed stone ballast and sea sand can be obtained using inexpensive raw materials.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram of an aggregate processing method for steelmaking slag according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of an aggregate processing method for steelmaking slag according to a second embodiment of the present invention.

Claims

A slag generated in the steel making process, a first step of adjusting the silica source consisting primarily of SiO _2, the formulation composed mainly of a cement-based solidifying material,
A second step for obtaining a granulated product by adding water necessary for granulation to the blend;
Have a third step of curing the granulated product at room temperature,
The blend is mainly composed of the slag having a silica source of 10 wt% or more and 30 wt% or less, the cement-based solidified material of 5 wt% or more and 20 wt% or less, and the remainder having a maximum particle size of 1 mm. An aggregate processing method for steelmaking slag characterized by the above.

A slag generated in the steel making process, a first step of adjusting the silica source consisting primarily of SiO _2, the formulation composed mainly of a cement-based solidifying material,
A second step for obtaining a granulated product by adding water necessary for granulation to the blend;
A third step of curing the granulated material at room temperature;
The granulated product after curing have a fourth step of hydrothermal treatment in a water vapor atmosphere of high temperature and high pressure,
The blend is mainly composed of the slag having a silica source of 10 wt% or more and 30 wt% or less, the cement-based solidified material of 5 wt% or more and 20 wt% or less, and the remainder having a maximum particle size of 1 mm. An aggregate processing method for steelmaking slag characterized by the above.

The method for assembling an aggregate of steelmaking slag according to claim 2, wherein the hydrothermal treatment is performed at a temperature range of 150 ° C to 250 ° C, a pressure range of 5 atm to 30 atm, and a treatment time of 0.5 hour or more. A method for producing an aggregate of steelmaking slag, which is performed under a condition of 10 hours or less.