JP2005060741A - Method for modifying steelmaking slag - Google Patents
Method for modifying steelmaking slag Download PDFInfo
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- JP2005060741A JP2005060741A JP2003207871A JP2003207871A JP2005060741A JP 2005060741 A JP2005060741 A JP 2005060741A JP 2003207871 A JP2003207871 A JP 2003207871A JP 2003207871 A JP2003207871 A JP 2003207871A JP 2005060741 A JP2005060741 A JP 2005060741A
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- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000005245 sintering Methods 0.000 claims abstract description 48
- 239000002956 ash Substances 0.000 claims abstract description 25
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- 238000007670 refining Methods 0.000 claims abstract description 11
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- 230000008569 process Effects 0.000 claims description 25
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 23
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- 238000002844 melting Methods 0.000 claims description 19
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- 229910000831 Steel Inorganic materials 0.000 claims description 15
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- 239000001301 oxygen Substances 0.000 claims description 9
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- 239000002245 particle Substances 0.000 claims description 6
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- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910001341 Crude steel Inorganic materials 0.000 description 1
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Images
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Processing Of Solid Wastes (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、上層路盤材、加熱アスファルト混合道路用材、アスファルト舗装用骨材等の有用な原料、硬化体・固化体原料、底質・海水浄化剤原料、もしくは鉄鋼、非鉄の製錬・精錬工程、廃棄物燃焼溶融炉、灰溶融炉、スラグ溶融炉における原料等に適用することができる改質製鋼スラグの製造方法に関するものである。
【０００２】
【従来の技術】
製鋼スラグは遊離ＣａＯ（以降ｆ．ＣａＯと記載する）を含み、その水和反応時の体積変化から膨脹崩壊性を示す。また、微小な亀裂、開気孔が多いため、吸水率が高く強度が低い。これにより、土木工事用の仮設材、道路の地盤改良材、下層路盤材等の低級用途でしか使用されておらず、より高級用途である上層路盤材、加熱アスファルト混合道路用材、アスファルト舗装用骨材等には用いられていない。しかし、低級用途の需要の低下から在庫が増大しており、発生した製鋼スラグの置き場等の問題も発生している。このため、上層路磐材、加熱アスファルト混合道路用材、アスファルト舗装用骨材等、高級用途への有効利用が必要である。従来、スラグ中のｆ．ＣａＯを減少させるスラグ熱間改質法、エージング法が種々検討されている。
【０００３】
スラグ熱間改質法は、特許文献１に提案されているように、製鋼スラグに、珪酸含有改質剤、炭素含有還元剤及び鉄スクラップを混合し、該混合物を、酸素ガス含有気体を供給しつつ還元性雰囲気に維持しながら溶融することを特徴とする製鋼スラグの熱間改質法である。
また、エージング法は、特許文献２に提案されているように、製鋼スラグを精錬時の装入副原料のＣａＯ量を５０ｋｇ／粗鋼ｔｏｎ以下およびスラグ塩基度３．５以下を基準として分別して、これに適合するスラグを放冷固化後、スラグ温度が４００〜１０００℃の顕熱を保持した状態で４０〜１００℃の温水槽に投入してｆ．ＣａＯの水和反応を促進させ安定化処理することを特徴とする方法である。
【０００４】
【特許文献１】
特開平６−１１５９８４号公報
【特許文献２】
特開平６−１８３７９２号公報
【０００５】
【発明が解決しようとする課題】
しかし、上記スラグ熱間改質法は、鉄スクラップを混合するため、１５５０℃以上に加熱し、該混合物を溶融する必要がある。この溶解に多量の熱と時間を必要とし、処理能力が低い。また還元性雰囲気で酸化鉄、酸化燐、酸化マンガン等の金属酸化物を還元して回収するため、ｆ．ＣａＯが完全にＳｉＯ２や低融点金属酸化物と反応しきれずに、改質スラグにはｆ．ＣａＯが残存していた。
また、上記エージング法は、改質可能なスラグを限定しており、改質できないスラグが約半数程度残存する。スラグの塩基度が高い場合、エージング期間を短くしたときにｆ．ＣａＯが低減できずにスラグの安定化が不十分となる。また、改質可能なスラグであっても数日以内のエージング期間が必要であり、処理能力が低い。また、１００℃以下程度での完全固相反応では、ｆ．ＣａＯが完全にＳｉＯ２等と反応しきれずに、スラグの膨脹、粉化を単に軽減することはできるものの、上層路盤材に使用可能なまでに安定化することはできない。また、改質スラグは、砕石等と比較すると吸水率が高く、強度が不十分である。
【０００６】
すなわち、従来の技術によって製造された改質スラグは、残存したｆ．ＣａＯを未だ含み、吸水率も高く強度が低いため、上層路盤材等の高級用途に、有効利用することが不可能であった。
本発明は、このような従来の技術の課題に鑑みてなされたもので、製鋼スラグの改質法を改良し、ｆ．ＣａＯのみならず、吸水率をも減少させる方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明の要旨は、以下の通りである。
（１） 製鋼スラグへ固体酸化発熱源を添加したものに、酸素ガスまたは含酸素ガスを通気して発熱させ、１１００℃以上で焼結処理することを特徴とする製鋼スラグの改質方法。
（２） 製鋼スラグに、ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する物質を添加した物を用いることを特徴とする（１）に記載の製鋼スラグの改質方法。
（３） 前記ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する物質として、高炉スラグ、脱珪スラグ、フライアッシュ、廃ガラス、コンクリート廃材、廃レンガ、アルミ灰、アルミドロス、アルミニウム精錬スラグ、都市ゴミ・下水汚泥の焼却灰、灰溶融スラグ、下水汚泥溶融スラグ、カーシュレッダーダスト燃焼灰、転炉ダスト、電炉ダスト、高炉二次灰、天然砂、珪砂、廃棄鋳砂、粘土、土壌、天然砕石、鉄鉱石の１種以上を用いることを特徴とする（２）に記載の製鋼スラグの改質方法。
（４） 前記ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する物質としてフライアッシュを用いる場合、製鋼スラグ１００質量部に対してフライアッシュ３０質量部以下添加した物であることを特徴とする（３）に記載の製鋼スラグの改質方法。
（５） 製鋼スラグとして、溶銑予備処理スラグ、溶融還元炉スラグ、転炉スラグ、電気炉スラグ、二次精錬スラグまたはステンレス鋼スラグの１種以上を用いることを特徴とする（１）〜（４）いずれかに記載の製鋼スラグの改質方法。
（６） 製鋼スラグとして粒径５ｍｍ以下のものを用いることを特徴とする（１）〜（５）いずれかに記載の製鋼スラグの改質方法。
（７） 焼結処理に際し、転炉、電炉、精錬炉、滓鍋、混銑車、エージング処理工程、高炉排滓工程、もしくは焼結装置の１種以上を用いることを特徴とする（１）〜（６）いずれかに記載の製鋼スラグの改質方法。
【０００８】
【発明の実施の形態】
本発明者らは上記課題を解決するために、製鋼スラグ中のｆ．ＣａＯを減少させると共に、開気孔を減少させることで吸水率を低減し、強度を向上させる製鋼スラグの改質法を発明するに至った。
以下に詳細を説明する。
まず、製鋼スラグへ固体酸化発熱源を添加したものに、酸素ガスまたは含酸素ガスを通気して発熱させ、１１００℃以上で焼結処理する方法について説明する。熱処理前の製鋼スラグの成分を必要に応じて適宜選択して、１１００℃以上で所望の時間の焼結処理を行うことで、焼結処理後のスラグ性状をｆ．ＣａＯ≦２．７質量％かつ吸水率≦４．０質量％に改質することができる。
ここで、ｆ．ＣａＯ≦２．７質量％であれば、改質製鋼スラグが膨張崩壊しても、水浸膨張比１．５％を達成でき、また吸水率≦４．０質量％であれば、さまざまな用途に用いても必要な強度を確保することができる。
【０００９】
また、１１００℃以上の焼結処理の所望の時間とは、特に規定するものではなく、焼結処理前の製鋼スラグの成分と焼結処理温度に応じて、適宜設定すれば良い。
まず、製鋼スラグ中のｆ．ＣａＯを減少させる点については、製鋼スラグにはＳｉＯ２、Ａｌ２Ｏ３が含まれていることに着目し、製鋼スラグ中のｆ．ＣａＯとＳｉＯ２、Ａｌ２Ｏ３との反応が起こる条件を検討したところ、製鋼スラグへ固体酸化発熱源を添加したものに、酸素ガスまたは含酸素ガスを通気して発熱反応させ、１１００℃以上で焼結処理すれば良いことを見出した。
【００１０】
本発明では、焼結処理というのは、製鋼スラグへ固体酸化発熱源を添加したものに、酸素ガスまたは含酸素ガスを通気し、これにより発熱することで、製鋼スラグ同士が反応し結合するという意味で用いている。
ここで、固体酸化発熱源とは酸素ガスと反応して発熱するものであれば、特に規定するものではないが、元素としてはＣ、Ａｌ、Ｓｉ等が例示でき、それらを含有するものとしては、各種炭材、コークス、廃プラスティック、金属Ｓｉ、金属Ａｌや、アルミ灰等がある。また、固体酸化発熱源を不可避的にも含む物質として、前記固体酸化発熱源を含む灰分、例えば、フライアッシュ、汚泥焼却灰、金属Ｓｉ、Ａｌの精錬工程で排出される含金属灰等が挙げられる。
これらの固体酸化発熱源と酸素ガスが反応すると発熱するため、この熱を利用してｆ．ＣａＯとＳｉＯ２との反応が起こる。通気するガスは、酸素ガス単独のものを用いると反応効率が良いので好ましいが、１１００℃以上に加熱できれば空気、もしくは含酸素の各種燃焼廃ガスを用いても良い。
【００１１】
熱処理前の製鋼スラグの成分としては、塩基度が小さい方が好ましい。ここで、スラグの塩基度とは、スラグのＣａＯとＳｉＯ２の質量比（ＣａＯ／ＳｉＯ２）である。すなわち、熱処理前スラグの塩基度が小さいほど、ｆ．ＣａＯに対するＳｉＯ２量が多くなるため、反応が促進される。
従って、１１００℃以上で焼結処理することで、スラグ中のｆ．ＣａＯとＳｉＯ２との反応が起こるが、熱処理前の製鋼スラグの成分を適宜選択することで、改質製鋼スラグ中のｆ．ＣａＯ≦２．７質量％となる様に実施することができる。
【００１２】
焼結処理を行った一例を図１に示すが、１１００℃以上の温度で焼結処理を行った場合は、改質スラグの塩基度が２．５以下であればｆ．ＣａＯを２．７質量％以下にまで低減でき、また更には改質スラグの塩基度が１．２であればｆ．ＣａＯを０．９質量％にまで低減可能である。
しかし、１１００℃未満の温度で焼結処理を行った場合は、改質スラグの塩基度が１．０〜２．０の範囲であっても、ｆ．ＣａＯを２．７質量％以下にまで低減することはできない。
従って、通常の製鋼スラグの組成域では、焼結温度を１１００℃以上とすることで、ｆ．ＣａＯ≦２．７質量％とすることができ、さらに塩基度が小さくなればなるほど低いｆ．ＣａＯとすることができる。
【００１３】
次に、製鋼スラグ中の吸水率を減少させる点についても、１１００℃以上で焼結処理すれば良いことを見出した。さらに、焼結処理前スラグの塩基度が小さいほど好ましいことが判明した。
これについては、１１００℃以上で焼結処理することで、スラグ中の液相率が増加することはもちろんのこと、焼結反応の際に、改質される製鋼スラグ粒各々の表面に、優先的に液相が拡がり、表面の亀裂、開気孔を優先的に改質するメカニズムが考えられる。こうして表面を優先的にかつ、表面から内部へと製鋼スラグに存在する亀裂、開気孔に液相が侵入することで空隙が減少し、これにより吸水率を減少させることができるものと考えられる。
また、ＳｉＯ２、Ａｌ２Ｏ３は融点を低下させる作用があるため、同じ焼結処理温度でも、反応に寄与する液相率が大きくなるため、その点でＳｉＯ２、Ａｌ２Ｏ３をより多く含む方が好ましい。
【００１４】
従って、１１００℃以上で焼結処理するに際し、焼結処理前の製鋼スラグの成分を適宜選択することで、スラグ中の液相率を大きくさせ、改質製鋼スラグ中の吸水率≦４．０質量％とすることができる。
焼結処理を行った一例を図２に示すが、１１００℃以上で焼結処理することで、前記したような表面を優先的に液相で覆って閉塞する現象が達成でき、温度を高くすればするほど、液相率も大きくなり、内部まで亀裂等の閉塞反応が起こるようになり、改質スラグとしての吸水率は低いものとなる。これらの方法により、吸水率≦４．０質量％が達成可能である。
【００１５】
焼結処理方法については特に規定されない。具体的には、酸素、酸素ガス含有気体としては空気の使用、酸素富化燃料バーナー、コークス燃焼、含酸素雰囲気下でのロータリーキルン・焼結機・回転炉床型炉・流動床加熱炉・バッチ式加熱炉・連続式加熱炉・キュポラ炉・コークスベッド式炉・電気抵抗加熱・高周波加熱・アーク加熱・マイクロ波加熱等が例示できるが、いずれもスラグを均一に１１００℃以上に焼結処理が可能なものであれば良い。
また、焼結処理温度の上限は特に規定するものではないが、コスト等を考慮すると、１２５０℃程度が好ましい。
さらに、焼結処理時間についても、上限は特に規定するものではないが、所望のスラグ成分に改質できる様に、塩基度や焼結処理温度等を考慮して、適宜設定すれば良く、生産性、コスト等を考慮して１０〜１５分程度が望ましい。
【００１６】
スラグ成分の分析には蛍光Ｘ線分析（ＪＩＳ Ｋ ０１１９）を、ｆ．ＣａＯの分析にはエチレングリコール抽出法ＩＣＰ発光分光分析を用いることができる。ｆ．ＣａＯの分析において同様にｆ．ＣａＯを抽出する方法としてＴＢＰ（トリブロムフェノール）法等があり、抽出が正しくできればいずれの方法を用いてもよい。
また、吸水率の測定には、ＪＩＳ Ａ１１０９もしくはＡ１１１０に規定される試験方法を用いた。
【００１７】
次に、製鋼スラグに、ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する物質を添加した物を焼結処理する方法について説明する。
塩基度の低い製鋼スラグを改質する場合は、上述の通り焼結処理を行うだけでも良いが、塩基度の高い製鋼スラグを改質する場合は、ＳｉＯ２源が不足するため、これを補うためにＳｉＯ２源を添加して熱処理することで、ｆ．ＣａＯの低減反応を実施できるため、好ましい。
ＳｉＯ２の添加量は、所望とする製鋼スラグ中のｆ．ＣａＯに応じて、適宜ＳｉＯ２を添加して熱処理すれば良い。その上、前述の通りＳｉＯ２には製鋼スラグ組成域において、融点を低下させる効果があるため、ＳｉＯ２源を添加することで、優先的に界面を改質する融液を増加して、改質を行うことが可能である。
【００１８】
また、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５はそれぞれ、ｆ．ＣａＯと反応してｆ．ＣａＯの低減を実施でき、さらに融点を低下させる効果があるため、上記と同様の効果を得ることができるため、添加することが好ましい。特に、ＦｅＯは酸化反応によりＦｅ２Ｏ３になるものもあり、その際に発熱するため、この熱を焼結反応に有効利用できるという作用もある。
さらに、ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の複数種を含有する物質を添加して、同様に焼結処理することでも良い。
【００１９】
従って、製鋼スラグ中には低融点金属酸化物、例えばＦｅＯ、ＭｎＯ、Ａｌ２Ｏ３、ＳｉＯ２が含まれているが、更にＳｉＯ２、Ａｌ２Ｏ３を加え、焼結処理することで、改質製鋼スラグの吸水率をより低減でき、強度の向上を達成できる。
また、同じスラグ組成であれば、温度が高い程、界面を優先的に改質する融液層が増加するため、吸水率はより小さくなる。しかし、反応温度を高くするには加熱・熱源が必要で、加熱・熱源コストが大きくなるため、可能な限り低い温度で反応させることがコスト的にも重要である。
以上の様に、ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する物質を添加することが好ましく、添加量や焼結処理時間は実験等で適宜設定すれば良い。
【００２０】
次に、ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する具体的な物質について説明する。これらの物質として、高炉スラグ、脱珪スラグ、フライアッシュ、廃ガラス、コンクリート廃材、廃レンガ、アルミ灰、アルミドロス、アルミニウム精錬スラグ、都市ゴミ・下水汚泥の焼却灰、灰溶融スラグ、下水汚泥溶融スラグ、カーシュレッダーダスト燃焼灰、転炉ダスト、電炉ダスト、高炉二次灰、天然砂、珪砂、廃棄鋳砂、粘土、土壌、天然砕石、鉄鉱石の１種以上を用いることで、本発明の改質は可能である。
これらは、一部廃棄物として指定されているものであり、安価に入手できるためコスト的に有利であり、廃棄物のリサイクル使用、廃棄物処理にもなるため好ましい。それぞれ改質されたスラグに悪影響を与える不純物を含まないものであれば特に限定されるものではない。もちろん、試薬のシリカも使用可能である。
【００２１】
さらに、ＳｉＯ２、Ａｌ２Ｏ３、ＦｅＯ、Ｆｅ２Ｏ３、Ｐ２Ｏ５の１種以上を含有する物質としてフライアッシュを用いる場合、製鋼スラグ１００質量部に対してフライアッシュ３０質量部以下添加した物であることについて説明する。
フライアッシュは平均粒径が約１０μｍで、非常に微粒である。これを製鋼スラグに添加して焼結処理を行う際に、フライアッシュは反応ガス流で飛ばされて、添加したフライアッシュが製鋼スラグに有効に作用せず、焼成処理速度が低下する現象が起こり易い。また、焼結装置で焼成した場合、反応ガス流で飛ばされたフライアッシュにより、ガス気道の目詰まりが起こり易く生産性を阻害する。特に、製鋼スラグ１００質量部に対してフライアッシュ３０質量部超添加した場合、ムラ焼けが発生して、良好な焼結を実施しづらくなる現象が見受けられる場合がある。従って、フライアッシュの配合は、製鋼スラグ１００質量部に対してフライアッシュ３０質量部以下添加した物であることが好ましい。
【００２２】
本発明に用いられる製鋼スラグは特に限定されるものではなく、溶銑予備処理スラグ、溶融還元炉スラグ、転炉スラグ、電気炉スラグ、二次精錬スラグまたはステンレス鋼スラグ等を使用することができ、既に冷却したものも使用できるが、溶融状態又は半凝固状態で熱量を保有するものを使用すると、本発明において加熱に必要なエネルギーを減少し得るので好ましい。
また、従来の畑処理を主としてきた、エージング、粉砕、粒度調整を行うような方式のスラグ処理では、スラグ処理後に粒径５ｍｍ以下の製鋼スラグが大量に発生するが、このサイズの製鋼スラグ粉では、有効利用用途がなく在庫となりやすい。しかし、本発明方法では、この様な従来用途のなかった粒径５ｍｍ以下の製鋼スラグ粉の塊成化が実現でき、粉分の再利用ができるようになり、販途を拡げることを可能とするものである。
【００２３】
焼結処理に際しては、前記の装置を用いて行えば良い。転炉、電炉、精錬炉、滓鍋、混銑車、高炉排滓工程を用いると、排出された製鋼スラグが高温状態であり、そのままスラグの顕熱を利用できるため、新たに加熱する温度が小さくなるため好ましい。特に、半溶融高炉スラグを滓鍋内に保持して使用すれば、更に加熱が必要なくなり好ましい。次いで、得られた物を前記装置・工程で酸素ガスを装置の底部から吹き込み、通ガスさせ、焼結反応を起こさせるようにして焼結処理させれば、熱効率の面から好ましい。
エージング処理工程を用いる場合、現状の畑方式スラグ処理工程の分級後に焼結機を増工程すればよいので、設備費が少なくてすむため好ましい。
【００２４】
さらに、ロータリーキルン・焼結機・回転炉床型炉・流動床加熱炉・バッチ式加熱炉・連続式加熱炉・キュポラ炉・コークスベッド式炉・電気抵抗加熱・高周波加熱・アーク加熱・マイクロ波加熱等を新たに設置、もしくは遊休設備を利用することで、製鋼スラグの焼結改質が可能である。
これら焼結装置を用いる場合は、固体のスラグを処理可能であるため、冷却した製鋼スラグで野積みされたスラグについても全量改質することができ、在庫削減にも繋がるため好ましい。
【００２５】
本発明の改質製鋼スラグの性状は、ｆ．ＣａＯ≦２．７質量％かつ吸水率≦４．０質量％である。ｆ．ＣａＯ≦２．７質量％であれば、改質製鋼スラグが膨張崩壊しても、水浸膨張比１．５％を達成できる。ここで、水浸膨張比とは、例えばＪＩＳ Ａ５０１５の附属書２で測定される値であり、鐵鋼スラグ協会による製鋼スラグ路盤設計施工指針によれば、上層路盤材等の高級用途に供するには、路盤の膨脹による支持力の低下を防ぐため水浸膨張比１．５％以下とすることが重要である。
中級の用途である加熱アスファルト混合道路用材、アスファルト舗装用骨材については水浸膨張比を２．０％以下とすることで使用可能であるため、本発明の改質製鋼スラグは十分満足できる。
【００２６】
また、一方吸水率は強度と相関があり、ＪＩＳ Ａ１１０９、または Ａ１１１０で規定されている吸水率３％以下を満足することで、これら高級用途に適用可能である。他のＪＩＳで吸水率が規定されていない高級用途においては、吸水率４％以下を満足することで、いずれの用途でも使用できる強度を確保することができる。従って、本発明の示すようにいずれの高級用途向けに於いても吸水率≦４．０質量％が、強度の点で重要である。
いずれの用途先への使用についても、スラグ組成、改質材の配合、焼結改質温度を適宜調製することで、本発明の方法により実施できる。
【００２７】
以上説明してきた規格が存在する高級用途以外の、中級用途として、本発明での上記のｆ．ＣａＯ≦２．７質量％かつ吸水率≦４．０質量％である改質製鋼スラグは、鉄鋼・非鉄の製錬・精錬工程、廃棄物燃焼溶融炉、灰溶融炉、スラグ溶融炉において主原料、副原料、耐火物保護剤、助剤、保温材原料、鎮静材原料、もしくは硬化体・固化体原料、底質・海水浄化剤原料として用いることができる。
【００２８】
【実施例】
本発明による製鋼スラグの改質法の実施例を示す。
製鋼スラグとして、溶銑予備処理スラグを用いた。表１は本実施例に供した溶銑予備処理スラグ、フライアッシュの組成分析値を示す。溶銑予備処理スラグＡは、塩基度が３．０でかつｆ．ＣａＯが１０質量％含まれる。溶銑予備処理スラグＢは、塩基度が４．５でかつｆ．ＣａＯが１６質量％含まれる。この溶銑予備処理スラグにＳｉＯ２、Ａｌ２Ｏ３を含むフライアッシュを改質剤として添加した。
【００２９】
溶銑予備処理スラグＡもしくはＢとフライアッシュをあらかじめ混合したもの１００質量部に対し、コークスを５質量部加えて造粒し、焼結機を用いて所定の温度にて焼結した。表２に実施水準を示す。
実施例１、２、３は、１１００℃以上で焼結したものであり、改質スラグ中のｆ．ＣａＯの濃度は２．７質量％以下で、いずれのスラグも水浸膨張比≦１．５％をクリアし、良好に改質された。また、吸水率も４質量％以下まで改質されており、強度が高い改質製鋼スラグが得られた。
これに対し、比較例１、２ともに、１１００℃未満で焼結させており、改質スラグ中のｆ．ＣａＯ濃度も高く、吸水率も高くなった。特に比較例２は、フライアッシュを３５質量部配合しているため、ムラ焼けも観察された。
【００３０】
【表１】
【表２】
【発明の効果】
本発明による改質製鋼スラグとその製造方法によれば、ｆ．ＣａＯが低く、かつ吸水率の小さい強度が高いスラグを得ることができる。しかも、比較的低温で確実な改質が可能となるので処理能力が向上し、改質されたスラグは、上層路盤材、加熱アスファルト混合道路用材、アスファルト舗装用骨材用途等の有用な原料に適用することができ、再生資源として高度に有効利用でき、また経済効果も大きい。
また、比較的に簡便なプロセスのため、既存の設備を利用可能であり、新たに設備を改造する場合でも軽微な改造で実施できる。
さらに、製鋼スラグの在庫の縮小に伴ない、在庫管理が容易となり、さらにスラグヤードの占有率を小さくできることから、スラグの運搬、払い出し等の作業の負荷が軽減できる。
【図面の簡単な説明】
【図１】改質製鋼スラグの塩基度に対するｆ．ＣａＯ。
【図２】改質製鋼スラグの焼結温度に対する吸水率。[0001]
BACKGROUND OF THE INVENTION
The present invention is a raw material for upper layer roadbed material, heated asphalt mixed road material, aggregate for asphalt pavement, hardened / solidified material, bottom material / seawater purifier raw material, or steel, non-ferrous smelting / refining process The present invention relates to a method for producing modified steelmaking slag that can be applied to raw materials in waste combustion melting furnaces, ash melting furnaces, and slag melting furnaces.
[0002]
[Prior art]
Steelmaking slag contains free CaO (hereinafter referred to as “f.CaO”) and exhibits expansion and disintegration from the volume change during the hydration reaction. Moreover, since there are many fine cracks and open pores, the water absorption is high and the strength is low. As a result, it is used only for low-grade applications such as temporary construction materials for civil engineering, road ground improvement materials, lower-layer roadbed materials, etc., and higher-grade roadbed materials, heated asphalt mixed road materials, and asphalt pavement bones. It is not used for materials. However, stocks are increasing due to a drop in demand for low-grade applications, and problems such as storage of generated steelmaking slag have also occurred. For this reason, it is necessary to effectively use it for high-grade applications such as upper-layer roadside materials, heated asphalt mixed road materials, and asphalt pavement aggregates. Conventionally, f. Various slag hot reforming methods and aging methods for reducing CaO have been studied.
[0003]
In the slag hot reforming method, as proposed in
In addition, as proposed in
[0004]
[Patent Document 1]
JP-A-6-115984 [Patent Document 2]
JP-A-6-183792 [0005]
[Problems to be solved by the invention]
However, in the slag hot reforming method, in order to mix iron scrap, it is necessary to heat the mixture to 1550 ° C. or higher to melt the mixture. This melting requires a large amount of heat and time, and the processing capacity is low. In addition, in order to reduce and recover metal oxides such as iron oxide, phosphorus oxide and manganese oxide in a reducing atmosphere, f. CaO cannot completely react with SiO 2 or the low melting point metal oxide, and the modified slag has f. CaO remained.
Moreover, the aging method described above limits slag that can be modified, and about half of the slag that cannot be modified remains. When the basicity of slag is high, when the aging period is shortened, f. CaO cannot be reduced and slag stabilization becomes insufficient. Further, even slag that can be modified requires an aging period of several days or less, and the processing capacity is low. In a complete solid phase reaction at about 100 ° C. or lower, f. Although CaO cannot completely react with SiO 2 or the like and expansion of slag and pulverization can be simply reduced, it cannot be stabilized until it can be used for the upper roadbed material. In addition, the modified slag has a high water absorption rate compared with crushed stone and the like, and the strength is insufficient.
[0006]
That is, the modified slag produced by the conventional technique is left in the remaining f. Since CaO is still contained and the water absorption rate is high and the strength is low, it cannot be effectively used for high-grade applications such as upper roadbed materials.
The present invention has been made in view of the problems of the prior art as described above, and has improved a method for reforming steelmaking slag, f. An object is to provide a method for reducing not only CaO but also water absorption.
[0007]
[Means for Solving the Problems]
The gist of the present invention is as follows.
(1) A method for reforming steelmaking slag, comprising adding a solid oxidation heat source to steelmaking slag and generating heat by aeration of oxygen gas or oxygen-containing gas and sintering at 1100 ° C. or higher.
(2) The steel manufacturing slag is obtained by using a material obtained by adding a substance containing at least one of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5. Of steelmaking slag.
(3) Blast furnace slag, desiliconized slag, fly ash, waste glass, concrete waste material, waste as a material containing one or more of the above SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , P 2 O 5 Brick, aluminum ash, aluminum dross, aluminum smelting slag, incineration ash of municipal waste and sewage sludge, ash melting slag, sewage sludge melting slag, car shredder dust combustion ash, converter dust, electric furnace dust, blast furnace secondary ash, natural sand The method for reforming steelmaking slag according to (2), wherein at least one of silica sand, waste cast sand, clay, soil, natural crushed stone, and iron ore is used.
(4) When fly ash is used as the substance containing one or more of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5 , fly ash is 30 masses per 100 parts by mass of steel slag. The method for reforming steelmaking slag as set forth in (3), wherein the steelmaking slag is added in a part or less.
(5) One or more of hot metal pretreatment slag, smelting reduction furnace slag, converter slag, electric furnace slag, secondary refining slag, or stainless steel slag is used as the steelmaking slag (1) to (4) ) A method for reforming steelmaking slag according to any one of the above.
(6) The steelmaking slag reforming method according to any one of (1) to (5), wherein a steelmaking slag having a particle diameter of 5 mm or less is used.
(7) In the sintering process, one or more of a converter, an electric furnace, a smelting furnace, a ladle, a kneading car, an aging process, a blast furnace discharge process, or a sintering apparatus is used. (6) The steelmaking slag reforming method according to any one of the above.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above-mentioned problems, the present inventors have introduced f. The inventors have invented a steelmaking slag reforming method that reduces CaO and reduces open pores to reduce water absorption and improve strength.
Details will be described below.
First, a method of performing a sintering process at 1100 ° C. or higher by aeration of oxygen gas or oxygen-containing gas to a steel slag added with a solid oxidation heat source to generate heat will be described. The components of the steelmaking slag before the heat treatment are appropriately selected as necessary, and the sintering treatment is performed at a temperature of 1100 ° C. or higher for a desired time, whereby the slag properties after the sintering treatment are changed to f. It can be modified to CaO ≦ 2.7% by mass and water absorption ≦ 4.0% by mass.
Where f. If CaO ≦ 2.7% by mass, even if the modified steelmaking slag expands and collapses, a water immersion expansion ratio of 1.5% can be achieved, and if the water absorption rate ≦ 4.0% by mass, various uses can be achieved. Even if it is used, it is possible to ensure the necessary strength.
[0009]
Further, the desired time for the sintering treatment at 1100 ° C. or higher is not particularly defined, and may be set as appropriate according to the steelmaking slag component before the sintering treatment and the sintering treatment temperature.
First, f. Regarding the point of reducing CaO, paying attention to the fact that SiO 2 and Al 2 O 3 are contained in the steelmaking slag, f. When the conditions under which the reaction between CaO and SiO 2 , Al 2 O 3 occurs were examined, an oxygen gas or oxygen-containing gas was passed through the steel slag to which a solid oxidation heat source was added, and an exothermic reaction was performed at 1100 ° C. or higher. And found that the sintering process should be performed.
[0010]
In the present invention, the sintering treatment means that a solid oxidation heat source is added to steelmaking slag, oxygen gas or oxygen-containing gas is vented, and heat is thereby generated, so that the steelmaking slags react and bond with each other. Used in meaning.
Here, the solid oxidation heat source is not particularly defined as long as it generates heat by reacting with oxygen gas, but examples of elements include C, Al, Si, and the like. , Various carbon materials, coke, waste plastic, metal Si, metal Al, aluminum ash, etc. Examples of substances that inevitably contain a solid oxidation heat source include ash containing the solid oxidation heat source, such as fly ash, sludge incineration ash, metal-containing ash discharged in the refining process of metal Si, Al, and the like. It is done.
When these solid oxidation heat sources react with oxygen gas, heat is generated, and this heat is used to f. A reaction between CaO and SiO 2 occurs. The gas to be ventilated is preferably oxygen gas alone because the reaction efficiency is good, but air or various oxygen-containing combustion waste gases may be used as long as the gas can be heated to 1100 ° C. or higher.
[0011]
As a component of steelmaking slag before heat processing, the one where basicity is smaller is preferable. Here, the basicity of slag is the mass ratio (CaO / SiO 2 ) of CaO and SiO 2 of slag. That is, the smaller the basicity of the slag before heat treatment, the f. Since the amount of SiO 2 with respect to CaO is increased, the reaction is promoted.
Therefore, f. In the slag can be obtained by sintering at 1100 ° C. or higher. Although the reaction between CaO and SiO 2 occurs, f. In the modified steelmaking slag can be selected by appropriately selecting the components of the steelmaking slag before the heat treatment. It can implement so that it may become CaO <= 2.7 mass%.
[0012]
An example of the sintering process is shown in FIG. 1, but when the sintering process is performed at a temperature of 1100 ° C. or higher, the basicity of the modified slag is 2.5 or less. F. If CaO can be reduced to 2.7% by mass or less, and the basicity of the modified slag is 1.2, f. CaO can be reduced to 0.9 mass%.
However, when the sintering process is performed at a temperature lower than 1100 ° C., even if the basicity of the modified slag is in the range of 1.0 to 2.0, f. CaO cannot be reduced to 2.7% by mass or less.
Therefore, in the composition range of normal steelmaking slag, the sintering temperature is set to 1100 ° C. or higher, so that f. CaO ≦ 2.7% by mass, and the lower the basicity, the lower the f. CaO can be used.
[0013]
Next, it was found that the water absorption in the steelmaking slag may be reduced by sintering at 1100 ° C or higher. Furthermore, it has been found that the smaller the basicity of the slag before sintering treatment, the better.
About this, the sintering process at 1100 ° C. or higher increases the liquid phase ratio in the slag, and also prioritizes the surface of each steelmaking slag grain to be modified during the sintering reaction. In particular, the liquid phase spreads and a mechanism for preferentially modifying surface cracks and open pores is conceivable. In this way, it is considered that the voids are reduced by the liquid phase entering the cracks and open pores existing in the steelmaking slag preferentially from the surface to the inside, thereby reducing the water absorption rate.
In addition, since SiO 2 and Al 2 O 3 have the effect of lowering the melting point, the liquid phase ratio contributing to the reaction is increased even at the same sintering temperature, so that SiO 2 and Al 2 O 3 are more effective in that respect. It is preferable to include a large amount.
[0014]
Therefore, when the sintering process is performed at 1100 ° C. or higher, the liquid phase ratio in the slag is increased by appropriately selecting the components of the steelmaking slag before the sintering process, and the water absorption ratio in the modified steelmaking slag ≦ 4.0. It can be made into the mass%.
An example of the sintering process is shown in FIG. 2, but by sintering at 1100 ° C. or higher, the above-described phenomenon that the surface is preferentially covered with a liquid phase and blocked can be achieved, and the temperature can be increased. The longer the liquid phase ratio is, the more clogging reaction such as cracking occurs inside, and the water absorption rate as the modified slag becomes low. By these methods, water absorption ≦ 4.0% by mass can be achieved.
[0015]
The sintering method is not particularly specified. Specifically, use of air as oxygen and oxygen gas-containing gas, oxygen-enriched fuel burner, coke combustion, rotary kiln, sintering machine, rotary hearth furnace, fluidized bed heating furnace, batch in oxygen-containing atmosphere For example, slag can be uniformly heated to 1100 ° C or higher, though it can be exemplified by type heating furnace, continuous heating furnace, cupola furnace, coke bed type furnace, electric resistance heating, high frequency heating, arc heating, microwave heating, etc. Anything is possible.
Further, the upper limit of the sintering temperature is not particularly specified, but is preferably about 1250 ° C. in consideration of cost and the like.
Furthermore, the upper limit of the sintering treatment time is not particularly specified, but it may be set as appropriate in consideration of basicity, sintering treatment temperature, etc. so that it can be modified to a desired slag component. About 10 to 15 minutes is desirable in consideration of properties and costs.
[0016]
X-ray fluorescence analysis (JIS K 0119) is used for analysis of slag components, f. For analysis of CaO, ethylene glycol extraction method ICP emission spectroscopic analysis can be used. f. Similarly in the analysis of CaO, f. There is a TBP (tribromophenol) method or the like as a method for extracting CaO, and any method may be used as long as the extraction can be performed correctly.
Moreover, the test method prescribed | regulated to JIS A1109 or A1110 was used for the measurement of a water absorption rate.
[0017]
Next, a method for sintering a steel product slag added with a material containing one or more of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5 will be described.
When modifying steelmaking slag with low basicity, the sintering process may be performed as described above. However, when modifying steelmaking slag with high basicity, the SiO 2 source is insufficient, so this is compensated. Therefore, by adding a SiO 2 source and heat-treating, f. Since reduction reaction of CaO can be implemented, it is preferable.
The amount of SiO 2 added is the desired f. Depending on CaO, SiO 2 may be added as appropriate and heat treatment may be performed. In addition, as described above, SiO 2 has the effect of lowering the melting point in the steelmaking slag composition region. Therefore, by adding the SiO 2 source, the amount of the melt that preferentially modifies the interface is increased and improved. It is possible to do quality.
[0018]
Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5 are each f. Reacts with CaO and f. Since CaO can be reduced and the melting point is further lowered, the same effect as described above can be obtained. In particular, FeO may be converted to Fe 2 O 3 by an oxidation reaction, and heat is generated at that time, so that this heat can be effectively used for the sintering reaction.
Further, a material containing plural kinds of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5 may be added and similarly sintered.
[0019]
Therefore, although low melting point metal oxides such as FeO, MnO, Al 2 O 3 and SiO 2 are contained in the steelmaking slag, SiO 2 and Al 2 O 3 are further added and sintered, The water absorption rate of the modified steel slag can be further reduced and the strength can be improved.
In addition, if the slag composition is the same, the higher the temperature, the more the melt layer that preferentially modifies the interface, so the water absorption becomes smaller. However, in order to increase the reaction temperature, a heating / heat source is required, and the heating / heat source cost increases. Therefore, it is important in terms of cost to perform the reaction at the lowest possible temperature.
As described above, it is preferable to add a substance containing one or more of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5. What is necessary is just to set suitably.
[0020]
Next, a specific substance containing one or more of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5 will be described. These materials include blast furnace slag, desiliconization slag, fly ash, waste glass, concrete waste, waste brick, aluminum ash, aluminum dross, aluminum refining slag, incineration ash of municipal waste and sewage sludge, ash melting slag, sewage sludge melting By using one or more of slag, car shredder dust combustion ash, converter dust, electric furnace dust, blast furnace secondary ash, natural sand, quartz sand, waste cast sand, clay, soil, natural crushed stone, iron ore, Modification is possible.
These are partly designated as wastes, and are advantageous in terms of cost because they can be obtained at low cost, and are also preferred because they can be used for waste recycling and waste disposal. There is no particular limitation as long as it does not contain impurities that adversely affect the modified slag. Of course, the reagent silica can also be used.
[0021]
Furthermore, when fly ash is used as a substance containing one or more of SiO 2 , Al 2 O 3 , FeO, Fe 2 O 3 , and P 2 O 5 , fly ash is 30 parts by mass or less with respect to 100 parts by mass of steel slag. Explain that it is an added product.
Fly ash is very fine with an average particle size of about 10 μm. When this is added to the steelmaking slag and the sintering process is performed, the fly ash is blown by the reactive gas flow, and the added fly ash does not effectively act on the steelmaking slag, resulting in a phenomenon in which the firing rate is reduced. easy. In addition, when fired by a sintering apparatus, the air ash is easily clogged by fly ash blown by the reaction gas flow, and productivity is hindered. In particular, when more than 30 parts by mass of fly ash is added to 100 parts by mass of steelmaking slag, uneven burning may occur and it may be difficult to perform good sintering. Accordingly, it is preferable that the fly ash is mixed with 30 parts by mass or less of fly ash with respect to 100 parts by mass of steel slag.
[0022]
Steelmaking slag used in the present invention is not particularly limited, and hot metal pretreatment slag, smelting reduction furnace slag, converter slag, electric furnace slag, secondary refining slag, or stainless steel slag can be used. Although an already cooled one can be used, it is preferable to use one having a calorie in a molten state or a semi-solid state because the energy required for heating in the present invention can be reduced.
In addition, in the slag processing that has been mainly used in conventional field treatment, such as aging, pulverization, and particle size adjustment, a large amount of steelmaking slag having a particle size of 5 mm or less occurs after slag treatment. There is no effective use, and it tends to be in stock. However, in the method of the present invention, agglomeration of steelmaking slag powder having a particle size of 5 mm or less, which has not been used in the past, can be realized, the powder content can be reused, and the sales potential can be expanded. To do.
[0023]
What is necessary is just to perform using the said apparatus in the case of a sintering process. When using a converter, electric furnace, refining furnace, ladle, chaotic car, blast furnace exhaust process, the discharged steelmaking slag is in a high temperature state, and the sensible heat of the slag can be used as it is. Therefore, it is preferable. In particular, it is preferable to use semi-molten blast furnace slag while holding it in a ladle so that heating is not necessary. Next, it is preferable from the viewpoint of thermal efficiency that the obtained product is sintered in such a manner that oxygen gas is blown from the bottom of the apparatus and passed through the apparatus / process to cause a sintering reaction.
In the case of using the aging treatment process, it is preferable to increase the number of sintering machines after classification in the current field slag treatment process, which is preferable because the equipment cost can be reduced.
[0024]
Furthermore, rotary kilns, sintering machines, rotary hearth furnaces, fluidized bed heating furnaces, batch heating furnaces, continuous heating furnaces, cupola furnaces, coke bed furnaces, electrical resistance heating, high frequency heating, arc heating, microwave heating It is possible to sinter and reform steelmaking slag by newly installing the above or using idle equipment.
When these sintering apparatuses are used, since solid slag can be processed, slag stacked with cooled steelmaking slag can be completely reformed, which leads to inventory reduction, which is preferable.
[0025]
The property of the modified steelmaking slag of the present invention is f. CaO ≦ 2.7% by mass and water absorption ≦ 4.0% by mass. f. If CaO ≦ 2.7 mass%, even if the modified steelmaking slag expands and collapses, a water immersion expansion ratio of 1.5% can be achieved. Here, the water immersion expansion ratio is, for example, a value measured in
Since the heated asphalt mixed road material and the asphalt pavement aggregate, which are intermediate uses, can be used by setting the water immersion expansion ratio to 2.0% or less, the modified steelmaking slag of the present invention is sufficiently satisfactory.
[0026]
On the other hand, the water absorption rate has a correlation with the strength, and when the water absorption rate is 3% or less as defined in JIS A1109 or A1110, it can be applied to these high-grade applications. In other high-grade applications where the water absorption rate is not prescribed by other JIS, the strength that can be used in any application can be ensured by satisfying the water absorption rate of 4% or less. Therefore, as shown in the present invention, the water absorption ≦ 4.0% by mass is important in terms of strength in any high-grade application.
The use to any application destination can be carried out by the method of the present invention by appropriately adjusting the slag composition, the blending of the modifier, and the sintering reforming temperature.
[0027]
The above-mentioned f. In the present invention is used as an intermediate application other than the high-grade application where the standard described above exists. Modified steelmaking slag with CaO ≤ 2.7 mass% and water absorption ≤ 4.0 mass% is the main raw material in steel and non-ferrous smelting and refining processes, waste combustion melting furnaces, ash melting furnaces, and slag melting furnaces It can be used as a secondary raw material, a refractory protective agent, an auxiliary agent, a heat insulating material raw material, a sedative raw material, or a cured / solidified raw material, a bottom sediment / seawater purifier raw material.
[0028]
【Example】
The Example of the modification method of the steelmaking slag by this invention is shown.
As the steelmaking slag, hot metal pretreatment slag was used. Table 1 shows the composition analysis values of the hot metal pretreatment slag and fly ash used in this example. The hot metal pretreatment slag A has a basicity of 3.0 and f. 10 mass% of CaO is contained. The hot metal pretreatment slag B has a basicity of 4.5 and f. 16 mass% of CaO is contained. Fly ash containing SiO 2 and Al 2 O 3 was added as a modifier to the hot metal pretreatment slag.
[0029]
5 parts by mass of coke was added to 100 parts by mass of the premixed hot metal slag A or B and fly ash, granulated, and sintered at a predetermined temperature using a sintering machine. Table 2 shows the implementation level.
Examples 1, 2, and 3 were sintered at 1100 ° C. or higher, and f. The concentration of CaO was 2.7% by mass or less, and all slags cleared the water immersion expansion ratio ≦ 1.5% and were well modified. Moreover, the water absorption was also modified to 4% by mass or less, and a modified steelmaking slag having high strength was obtained.
On the other hand, both Comparative Examples 1 and 2 were sintered at less than 1100 ° C., and f. The CaO concentration was high and the water absorption rate was also high. In particular, since Comparative Example 2 contains 35 parts by mass of fly ash, uneven burn was also observed.
[0030]
[Table 1]
[Table 2]
【The invention's effect】
According to the modified steelmaking slag and its manufacturing method according to the present invention, f. A slag having low CaO and high strength with low water absorption can be obtained. In addition, since it can be reliably modified at relatively low temperatures, the processing capacity is improved, and the modified slag can be used as a useful raw material for upper roadbed materials, heated asphalt mixed road materials, asphalt pavement aggregates, etc. It can be applied, can be used effectively as a recycled resource, and has a great economic effect.
In addition, since the process is relatively simple, existing equipment can be used, and even when the equipment is newly modified, it can be implemented with minor modifications.
Furthermore, as the stock of steelmaking slag is reduced, inventory management becomes easy and the slag yard occupancy can be reduced, so the burden of work such as slag transportation and dispensing can be reduced.
[Brief description of the drawings]
FIG. 1 shows the f. Vs. basicity of modified steel slag. CaO.
FIG. 2 shows the water absorption rate relative to the sintering temperature of the modified steel slag.
Claims (7)
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