JP4274834B2 - Slag stability evaluation method - Google Patents
Slag stability evaluation method Download PDFInfo
- Publication number
- JP4274834B2 JP4274834B2 JP2003095404A JP2003095404A JP4274834B2 JP 4274834 B2 JP4274834 B2 JP 4274834B2 JP 2003095404 A JP2003095404 A JP 2003095404A JP 2003095404 A JP2003095404 A JP 2003095404A JP 4274834 B2 JP4274834 B2 JP 4274834B2
- Authority
- JP
- Japan
- Prior art keywords
- slag
- sieve
- treatment
- hydration
- evaluation method
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
Landscapes
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Investigating And Analyzing Materials By Characteristic Methods (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Description
【0001】
【発明の属する技術分野】
本発明は、製鉄所などで発生する高炉、転炉、電気炉スラグなどの鉄鋼スラグの安定性を評価する方法に関するものである。
【0002】
【従来の技術】
製鉄所などで高炉、転炉、電気炉といった精錬炉から発生する鉄鋼スラグは、省資源、省エネルギーの観点から、環境への負荷を低減させるリサイクル材料として、数々の特性を生かして各方面で利用されている。
【0003】
例えば、高炉スラグや製鋼スラグが水と反応して次第に硬化していく「水硬性」は道路用の路盤材に適しているし、あるいは製鋼スラグの有する「硬質」かつ「耐磨耗」な特性は道路用のアスファルト・コンクリート用骨材に適している。
【0004】
これらの用途に用いられるスラグは長期にわたって安定であることが重要であることから、例えばJIS A5015「道路用鉄鋼スラグ」に規定されるように、スラグを破砕後、数ヶ月の間、空気および水と反応させる「エージング」処理を行い十分に安定化させることが必要とされている。
【0005】
中でも、製鋼スラグは遊離のCaOやMgOなど消化性の物質を含んでおり長期にわたって膨張する現象があることから、エージングによってスラグが十分に安定になったかどうかを評価する方法として、同じくJIS A5015「道路用鉄鋼スラグ」中に附属書2として「水浸膨張試験方法」が規定されている。
【0006】
附属書2に記載された方法は、ある粒度分布に従って粒度調整された試料を規定の容器(モールド)内に突き固めて充填したものを、80℃の温水に6時間保持したのちに放冷させる操作を1日1回、10日間繰り返して養生させ、養生後のモールド内試料の高さを測定してその膨張量からスラグの安定度を評価するものであり、長年、道路用鉄鋼スラグの有効な指標として用いられてきた。
【0007】
また、上記方法ではスラグの安定性評価に10日間という長い時間を有するが、例えばセメントや耐火物など、同じく消化性物質を含む材料の安定性をより迅速に評価する方法として、密封加圧容器と加熱装置からなる「オートクレーブ」装置を用いて100℃以上の高温・高圧下に試料をおいて、比較的、短時間に水和反応をおこさせた後に、例えばASTMC151−08「ポルトランドセメントの膨張試験方法」に記載されているように試料の長さを測定する方法や、JIS R2211「塩基性耐火れんがの消化性の試験方法」に記載されているように試料の圧縮強さの低下率を測定する方法、あるいは、非特許文献1に記載されているように、処理後の試料を篩い分けして篩い下重量の割合(粉化率)を測定して材料の安定度を評価するものも知られている。
【0008】
【非特許文献1】
鉄と鋼、第64年(1978)第10号、P−68
【0009】
【発明が解決しようとする課題】
しかし、鉄鋼スラグを、例えば道路用以外の新たな用途に利用しようとする際には、上記の従来技術における安定性評価方法では次のような問題点がある。
【0010】
すなわち、本発明者らはこれらの鉄鋼スラグ、中でも長期膨張性を有する製鋼スラグを上述のように十分なエージング処理を施したものを、他の結合材とともに混ぜ合わせて固める固化体の骨材に用いることができないかと研究開発を行ってきた。ここで、様々なエージング処理を施した製鋼スラグを骨材に用いた固化体の長期安定性を推定するため、固化体そのものの安定性促進試験を行って固化体の破壊状況を調べ、同時にこれらに用いた骨材である製鋼スラグについては上記の方法を用いてその安定性を評価し、固化体に適用が可能な製鋼スラグの安定化の条件を見出そうと検討を行った。
【0011】
しかしながら、JIS A5015「道路用鉄鋼スラグ」に記載されている「水浸膨張試験方法」においては、モールド内のある容積の製鋼スラグの固まり(群)としての平均的な膨張性が評価できるが、固化体を破壊に至らせるような、構成要素の一つであるスラグ粒の個々の膨張に伴う破壊は測定できないため、膨張率が小さくても固化体が破壊するような現象が見られ、的確にスラグの安定性が評価できていないことが判明した。
【0012】
また、ASTMC151−08「ポルトランドセメントの膨張試験方法」に記載されているような試料の長さを測定する方法、 あるいはJIS R2211「塩基性耐火れんがの消化性の試験方法」に記載されている試料の圧縮強さの低下率を測定する方法などは成形体の膨張挙動は評価できるが、個々のスラグ粒の安定性評価は困難である。
【0013】
また、非特許文献1に記載されている粉化率を測定する方法では、水和膨張の結果として生じた粉分だけでは測定値が小さい、あるいはばらつきが大きくて、固化体を破壊に至らせしめるスラグの判別がつきずらく、当該論文中にも「スラグの崩壊性の表示として適当な方法がない」と述べられているように、やはり個々のスラグ粒の安定性を評価するには難しい。
【0014】
本発明の目的は、上記従来技術の問題点を解決しエージング処理を施した鉄鋼スラグの安定性をより精度良く評価する方法を提供することにある。
【0015】
つまり、エージング処理等によって安定化させたスラグ中に残存する、今なお未崩壊の個々のスラグ粒の存在確率を的確に把握することが本発明の目的である。
【0016】
【課題を解決するための手段】
本発明者らは、前述したように、様々なエージング処理を施した製鋼スラグを骨材に用いた固化体の安定性促進試験における固化体の破壊状況を調べ、同時にこれら骨材に用いた製鋼スラグについても様々な方法によってその安定性(崩壊性)を測定し、両者の間に定量的な相関が見いだせられないか解析と検討を重ねた結果、以下の発明にて上記の課題が解決される知見を得た。
(1)エージング処理の後、第1の篩い目で細粒分を除去した篩い上のスラグをさらに水和促進処理し、これを乾燥させたものを、前記第1の篩い目で分級し、さらにこの篩い下を前記第一の篩い目よりも小さな第2の篩い目で篩い分け、
(第2の篩い目の篩い下の質量)/(水和促進処理前の第1の篩い上の質量)×100(%)をスラグ崩壊率とすることを特徴とするスラグの安定性評価方法。
(2)水和促進処理がJIS A5015「道路用鉄鋼スラグ」の「水浸膨張試験方法」、又はASTMC151−08「ポルトランドセメントの膨張試験方法」に記載された処理であることを特徴とする前記(1)記載のスラグの安定性評価方法。
(3)第1の篩い目が、第2の篩い目よりJIS Z8801−1の規定において1段又は2段粗いことを特徴とする前記(1)又は(2)記載のスラグの安定性評価方法。
(4)第1の篩い目を9.5mmとし、第2の篩い目を8mmとすることを特徴とする前記(1)〜(3)の何れか1項に記載のスラグの安定性評価方法。
(5)50mm以上の粗粒分も除去したスラグを水和促進処理することを特徴とする前記(1)〜(4)の何れか1項に記載のスラグの安定性評価方法。
(6)エージング処理が、少なくとも大気下にて1ヶ月以上、又は常圧若しくは加圧の蒸気下にて6時間以上放置する処理であることを特徴とする前記(1)〜(5)の何れか1項に記載のスラグの安定性評価方法。
【0017】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【0018】
本発明者らが、エージング処理を施した種々のスラグの安定性を調査した結果、従来、報告されているスラグの膨張性を評価するための「水浸膨張試験」や「オートクレーブ膨張試験」によれば確かにスラグは水和反応が促進され、消化性を有する一部のスラグ粒が水和に伴い膨張、破壊していることは明らかであり、当然のことながらスラグをエージング処理すればするほどこの膨張率が低減することもきちんと評価できることはわかっていた。
【0019】
しかしながら、様々なエージング処理を施した製鋼スラグを骨材に用いた固化体の長期安定性を推定するため、固化体そのものの安定性促進試験を行って固化体の破壊状況を調べ、同時にこれらに用いた骨材である製鋼スラグについても、上記の膨張率を測定して、固化体に適用が可能な製鋼スラグの条件を見出そうと両者の相関関係を調べてみても、この膨張率は先にも述べたようにある容積のスラグの固まり(群)としての平均的な膨張挙動を評価しており、実際に膨張率が小さくても、中に数個の崩壊するスラグが含まれていれば固化体の破壊をもたらすことが推定された。
【0020】
そこで次に、膨張率ではなく、同じ水和促進処理後のスラグを篩い分けして、篩い下の重量から崩壊率(粉化率)を測定して同じく固化体の破壊状況との相関関係を調べたが、この方法では逆に、様々なエージング処理を施してもスラグの崩壊率が大きくばらつき、やはり正当な評価が難しいという結果となった。
【0021】
しかし、上記の方法によれば、明らかに崩壊した個々のスラグ粒を測定できているはずであり、このスラグの崩壊率が大きくばらつく原因を究明するために、本発明者らがさらに種々の検討を行った結果、スラグの安定性を的確に評価する方法として次のような知見を得た。
【0022】
すなわち、第1の篩い目で分級された篩い上のスラグを水和促進処理後、同じ第1の篩い目でスラグを篩い分けして、篩い下のスラグ粒を詳細に観察したところ、水和処理で崩壊に至った破片状あるいは粉末状のスラグの中に明らかに崩壊していないと見受けられる比較的大きなスラグ粒が混入していることが判明した。
【0023】
この原因としては、これらのスラグは安定性評価のため、水和促進処理の事前に必要とされる粒度以上に分級処理によって細粒分が除去されるが、この際に全ての小さなスラグが完全に篩われるわけではなく、どうしても一部の細粒なスラグが篩い上に残ってしまい、水和促進後の分級処理時にこれらのスラグが篩い下に落ちたものと考えられる。
【0024】
そこで、水和促進処理後のスラグを第1の篩い目で分級し、この篩い下を第1の篩い目よりも小さな第2の篩い目でさらに篩うと、明白なことながら未崩壊のスラグがほぼ完全に除去される結果、水和促進処理で崩壊に至ったスラグだけを測定できることとなり、この真の崩壊率を用いることによって、元々のスラグのエージング処理が十分であればこの崩壊率も減少し、さらにはこの崩壊率が固化体の安定性(破壊状況)に密接に関係することなどを明らかにすることができた。
【0025】
図1は本発明の原理を示す図である。ここでは一例として、事前にエージング処理した10mm以上25mm以下のスラグを測定対象とするため、JIS Z8801−1に規定された呼び寸法(篩い目の1辺の長さ)22.4mm及び9.5mmの篩い目を用いて事前にスラグを分級する。エージング処理としては、大気中で少なくとも1ヶ月放置したのちに、必要に応じて180℃で6時間蒸気エージングを実施した。
【0026】
このスラグを80℃の温水への浸漬(6時間/日×10日)あるいはオートクレーブ(180℃(約20気圧)×6時間)などを用いて水和促進処理を行い乾燥させたのち、事前処理と同じく9.5mmの篩い目で分級する。しかし、この篩い下には、本来であれば事前の分級処理時に篩い落とされていなければならない未崩壊の安定なスラグ塊も未だ存在してしまう。従って、JIS Z8801−1に準じてもう1段小さな篩い目である8mmを使って、上記の9.5mmの篩い下のスラグをさらに分級する(W3)。なお図中には、この1段小さな篩い目の下のスラグをさらに2mmの篩いで篩って、破片状のスラグと粉状のスラグにわけた例をも示した(W2、W1)。
【0027】
この図から、本発明によれば、真の崩壊率は元のスラグ量W0に対する粉分のW1と破片状のスラグ量W2の和で示されることが自明である。
【0028】
しかしながら、従来は粉分(W1)と破片状分(W2)ならびに未崩壊スラグ(W3)の和をもって崩壊率と見なしていたわけである。事前の分級は当然のことながら一定条件で行われていたとしても、本来であれば篩い落とされているはずのスラグW3は処理時にばらつくことが容易に想定でき、これが測定値のばらつきをもたらしていたことを本発明者らは知見した。
【0029】
また、崩壊率を一部、粉化率と称する報告があるように、水和処理で生じた粉分W1のみを用いて崩壊率と見なしていた場合もあり、この際には当然のことながら真の崩壊率よりも相当小さく評価していることになる。
【0030】
ここで、分級に用いる篩いとしては、わが国においては、上述のJIS Z 8801−1で規定されるものが一般的である。さらに、事前分級処理に用いた篩い目よりも小さな篩いを用いて最終分級するのが本発明の特徴であるが、これにはJIS Z 8801−1で規定した1〜2段ほど小さな篩い目を用いることが好ましく、径の小さなスラグの測定ほど1段下の篩い目で十分でなる。事前の分級処理は、例えば大型の分級器で行われるのが一般的であるが、水和促進処理後は崩壊したスラグ量も少なく、精度を高めるためにもロータップ試験機などを用いるのが一般的で、水和促進処理後のスラグを十分に乾燥させたものを、少なくとも3分以上分級したほうが測定精度上、好ましい。
【0031】
スラグの水和促進処理としては、多くの実績があるJIS A5015「道路用鉄鋼スラグ」の「水浸膨張試験方法」(80℃温水に10日間)や、短時間で処理が可能なASTMC151−08「ポルトランドセメントの膨張試験方法」に準じた方法が一般的であり、後者であれば180℃で3〜6時間の処理で評価に十分なデータが得られる。
【0032】
本発明はエージング処理を行った後のスラグ崩壊率を評価することが目的であるので、エージング処理後、未崩壊のスラグを分級するため、第1の篩い目で細粒分を除去することは必須である。
【0033】
ここで、元のスラグの粒径が50mm以下、好ましくは25mm以下であれば、粗粒を事前にあえて分級する必要はない。一方、スラグの粒径が50mm超、好ましくは25mm超であれば、混在する地金分の混入をさけるため、これらの粗粒も除去した上で水和促進処理に用いることが好ましい。
【0034】
また、エージング処理としては、消化成分が水和反応するためにも、室温で1か月以上、又は常圧若しくは加圧の蒸気下にて6時間以上放置することが好ましい。加圧の上限は特に定めることなく本発明の効果を得ることができるが、特に水和反応の速度が遅いMgOの水和促進効果を効率的かつ経済的に得るためには1〜10気圧で処理することが好ましい。
【0035】
さらに、評価に用いるスラグの量は特に問わないが、スラグの安定化のためにエージング処理を施せば施すほど、スラグの崩壊率は減少してくるので、測定値の精度を高めるためにも、少なくとも5kg以上を用いたほうが良い。
【0036】
また、スラグによっては岩石状に表面がつるつるしたものもあれば、砂岩状にざらついているものもあり、特に後者の場合は粉分がでるので、事前の分級後に水洗いを行って、極力表面の付着粉分を除去したほうが測定精度が良い。
【0037】
【実施例】
(本発明例)
図2は、室温で少なくとも1ヶ月放置するエージング処理によって安定化させた製鋼スラグを、JIS Z 8801−1で規定される呼び寸法22.4mmならびに9.5mmで篩ったもの(粒度範囲10〜25mm)5kgを、JISA5015「道路用鉄鋼スラグ」の「水浸膨張試験方法」に準じて80℃の温水に10日間、スラグを浸漬させて水和促進処理を施したのちに110℃24時間乾燥させた上で、図1に示したような方法によってJIS Z 8801−1で規定される呼び寸法9.5mmの篩い目を用いて分級し、その篩い下をJISZ8801−1に規定された呼び寸法8mmの篩いでさらに分級し、(8mmの篩い下のスラグ質量)/(水和促進処理処理前の10〜25mmのスラグ質量)×100%により求めた真の崩壊率と、同スラグを骨材に用いて、他に高炉スラグ微粉末を主な結合材として混ぜ合わせて固めた固化体(直径100mm*高さ200mm)を、スラグと同様に安定性確認のための促進評価(80℃の温水に4週間浸漬)した際の固化体の破壊率との相関を示したグラフである。尚、固化体の破壊率は促進評価により崩壊した試料個数/評価に供した試料個数により求めた。
【0038】
この図から、本発明によるスラグの真の崩壊率が約3%を超えると、該スラグを骨材に用いた固化体の試料も破壊を生じるため、崩壊率3%以下のエージング処理を施したスラグは、固化体の骨材として適していることがわかった。
(比較例1)
図3は、室温で少なくとも1ヶ月放置するエージング処理によって安定化させた製鋼スラグを、JIS Z 8801−1で規定される呼び寸法22.4mmならびに9.5mmで篩ったもの(粒度範囲10〜25mm)を、JIS A5015「道路用鉄鋼スラグ」中に附属書2として「水浸膨張試験方法」中に規定されている容器(モールド)内に突き固めて充填したものを、80℃の温水に6時間保持したのちに放冷させる操作を1日1回、10日間繰り返して養生させ、養生後のモールド内試料の高さを測定して求めた膨張率と、同スラグを骨材に用いて、他に高炉スラグ微粉末を主な結合材として混ぜ合わせて固めた固化体(直径100mm*高さ200mm)を、スラグと同様に安定性確認のための促進評価(80℃の温水に4週間浸漬)した際の固化体の破壊率との相関を示したグラフである。固化体の破壊率は本発明例と同一の方法により求めた。
【0039】
この図から、従来の評価方法である膨張率を用いても、0.3%以上の範囲になると当該スラグを用いた固化体が破壊したり、破壊しなかったりしており、安定な固化体に適したスラグの条件を見出すことはできなかった。
(比較例2)
図4は、室温で少なくとも1ヶ月放置するエージング処理によって安定化させた製鋼スラグを、JIS Z 8801−1で規定される呼び寸法22.4mmならびに9.5mmで篩ったもの(粒度範囲10〜25mm)5kgを、JISA5015「道路用鉄鋼スラグ」の「水浸膨張試験方法」に準じて80℃の温水に10日間、スラグを浸漬させて水和促進処理を施したのちに110℃24時間乾燥させた上で、事前の分級処理に用いたと同じJIS Z 8801−1で規定される呼び寸法9.5mmの篩いで分級した際の(9.5mmの篩い下のスラグ質量)/(水和促進処理前の10〜25mmのスラグ質量)×100%により求めた、いわゆるこれまで言われてきた崩壊率と、同スラグを骨材に用いて他に高炉スラグ微粉末を主な結合材として混ぜ合わせて固めた固化体(直径100mm*高さ200mm)を、スラグと同様に安定性確認のための促進評価(80℃の温水に4週間浸漬)した際の固化体の破壊率との相関を示したグラフである。固化体の破壊率は本発明例と同一の方法により求めた。
【0040】
この図から、やはり従来の方法によるスラグの崩壊率では、これまで説明してきたように一部未崩壊のスラグ粒が混入していることから、崩壊率が2%以上の範囲になると比較例1と同様に当該スラグを用いた固化体が破壊したり、破壊しなかったりしており、安定な固化体に適したスラグの条件を見出すことはできなかった。
【0041】
【発明の効果】
本発明によれば、鉄鋼スラグ、中でも消化性の成分を有し長期にわたって膨張する性質のある製鋼スラグを、道路用以外の例えば固化体といった新たな用途に利用しようとする際に、エージング処理を施し安定化させたスラグの安定性を精度良く評価することができる。
【図面の簡単な説明】
【図1】本発明の原理を示す図。
【図2】本発明によるスラグの崩壊率と当該スラグを骨材に用いた固化体の破壊率との関係を示す図。
【図3】従来技術によるスラグの膨張率と当該スラグを骨材に用いた固化体の破壊率との関係を示す図。
【図4】従来技術によるスラグの崩壊率と当該スラグを骨材に用いた固化体の破壊率との関係を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for evaluating the stability of steel slag such as blast furnaces, converters, and electric furnace slag generated in steelworks.
[0002]
[Prior art]
Steel slag generated from smelting furnaces such as blast furnaces, converters, and electric furnaces at steelworks is used in various fields as a recycled material that reduces environmental burden from the viewpoint of resource saving and energy saving. Has been.
[0003]
For example, “hydraulicity” in which blast furnace slag and steelmaking slag gradually harden by reacting with water is suitable for roadbed materials, or the characteristics of “hard” and “abrasion resistance” of steelmaking slag. Is suitable for road asphalt and concrete aggregate.
[0004]
Since it is important that the slag used in these applications is stable over a long period of time, air and water are used for several months after the slag is crushed, for example, as defined in JIS A5015 “Steel Slag for Roads”. It is necessary to sufficiently stabilize by performing an “aging” treatment for reacting with azobenzene.
[0005]
Among them, steelmaking slag contains digestible substances such as free CaO and MgO and has a phenomenon of expanding over a long period of time. Therefore, as a method for evaluating whether slag has been sufficiently stabilized by aging, JIS A5015 “ The “water immersion expansion test method” is defined as
[0006]
In the method described in
[0007]
In the above method, the slag stability evaluation has a long time of 10 days. For example, as a method for more quickly evaluating the stability of materials containing digestible substances such as cement and refractory, a sealed pressurized container is used. A sample is placed under a high temperature and high pressure of 100 ° C. or higher using an “autoclave” apparatus consisting of a heating device and a hydration reaction in a relatively short time. For example, ASTM C151-08 “Expanding Portland cement” The method of measuring the length of the sample as described in "Test method" and the rate of decrease in the compressive strength of the sample as described in JIS R2211 "Test method of digestibility of basic refractory bricks" Method of measurement, or as described in
[0008]
[Non-Patent Document 1]
Iron and steel, 64th (1978) No. 10, P-68
[0009]
[Problems to be solved by the invention]
However, when steel slag is to be used for new uses other than for roads, for example, the above-described conventional stability evaluation method has the following problems.
[0010]
In other words, the present inventors used these steel slags, especially steelmaking slags having long-term expansibility, which have been subjected to sufficient aging treatment as described above, together with other binders to solidify aggregates to be solidified. Research and development has been carried out to see if it can be used. Here, in order to estimate the long-term stability of the solidified body using steelmaking slag that has been subjected to various aging treatments, the stability of the solidified body itself is investigated by examining the stability of the solidified body. The steelmaking slag, which is the aggregate used in the above, was evaluated for its stability using the above-mentioned method, and a study was conducted to find out the conditions for stabilizing the steelmaking slag that can be applied to the solidified body.
[0011]
However, in the “water immersion expansion test method” described in JIS A5015 “steel slag for roads”, the average expansibility as a mass (group) of steel slag of a certain volume in the mold can be evaluated. Since the failure due to individual expansion of slag grains, which is one of the components that causes the solidified body to break, cannot be measured, a phenomenon that the solidified body is broken even when the expansion coefficient is small is observed. It was revealed that the stability of slag could not be evaluated.
[0012]
Also, a method for measuring the length of a sample as described in ASTM C151-08 “Method for testing the expansion of Portland cement”, or a sample described in JIS R2211 “Test method for digestibility of basic refractory bricks” Although the method of measuring the rate of decrease in the compressive strength can evaluate the expansion behavior of the molded body, it is difficult to evaluate the stability of individual slag grains.
[0013]
Further, in the method for measuring the pulverization rate described in
[0014]
An object of the present invention is to provide a method for more accurately evaluating the stability of steel slag that has been subjected to the aging treatment by solving the problems of the prior art.
[0015]
That is, it is an object of the present invention to accurately grasp the existence probability of individual slag grains that remain in the slag stabilized by aging treatment or the like and are still uncollapsed.
[0016]
[Means for Solving the Problems]
As described above, the present inventors investigated the fracture state of the solidified body in the stability promotion test of the solidified body using steelmaking slag subjected to various aging treatments as an aggregate, and at the same time, steelmaking used in these aggregates. The stability (disintegration) of slag was also measured by various methods, and as a result of repeated analysis and examination of whether a quantitative correlation could be found between them, the above problems were solved by the following invention. I got the knowledge.
(1) After the aging treatment, the slag on the sieve from which fine particles have been removed by the first sieve is further subjected to hydration promotion treatment, and the dried slag is classified by the first sieve, Further, the sieve is screened with a second sieve smaller than the first sieve,
(Mass under second sieve) / (Mass on first sieve before hydration promotion treatment) × 100 (%) is defined as the slag disintegration rate, and the slag stability evaluation method .
(2) The hydration accelerating treatment is a treatment described in “Water immersion expansion test method” of JIS A5015 “Steel slag for road” or ASTM C151-08 “Expansion test method of Portland cement”. (1) The stability evaluation method of slag as described.
(3) The slag stability evaluation method according to (1) or (2) above, wherein the first sieve mesh is rougher by one or two stages in accordance with JIS Z8801-1 than the second sieve mesh. .
(4) The slag stability evaluation method according to any one of (1) to (3) above, wherein the first sieve is 9.5 mm and the second sieve is 8 mm. .
(5) The slag stability evaluation method according to any one of (1) to (4), wherein the slag from which coarse particles of 50 mm or more have been removed is subjected to hydration promotion treatment.
(6) Any of the above (1) to (5), wherein the aging treatment is a treatment which is allowed to stand for at least 1 month in the atmosphere or at least 6 hours under normal pressure or pressurized steam. The slag stability evaluation method according to
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0018]
As a result of investigating the stability of various slags that have been subjected to aging treatment, the present inventors have heretofore reported the "water immersion expansion test" and "autoclave expansion test" for evaluating the expansion of slag. According to the slag, it is clear that the hydration reaction is promoted, and that some of the digestible slag grains are expanded and destroyed as a result of hydration. It was known that the reduction in the expansion rate can be properly evaluated.
[0019]
However, in order to estimate the long-term stability of the solidified body using steelmaking slag that has been subjected to various aging treatments, the stability of the solidified body itself is examined by examining the stability of the solidified body, and at the same time, Even for steelmaking slag, which is the aggregate used, even if we measured the above expansion coefficient and investigated the correlation between them to find out the conditions for steelmaking slag applicable to solidified bodies, this expansion coefficient is As mentioned earlier, we are evaluating the average expansion behavior as a group (group) of slag of a certain volume, and even if the expansion rate is actually small, several slags that collapse are included. It was estimated that this would cause destruction of the solidified body.
[0020]
Therefore, instead of the expansion rate, the slag after the same hydration promotion treatment is screened and the disintegration rate (pulverization rate) is measured from the weight under the screen, and the correlation with the fracture state of the solidified body is also found. On the contrary, with this method, even if various aging treatments were applied, the collapse rate of slag varied widely, and it was still difficult to make a valid evaluation.
[0021]
However, according to the above method, individual slag grains that have clearly collapsed should have been measured. In order to investigate the cause of the large variation in the decay rate of the slag, the present inventors have conducted various further studies. As a result, the following knowledge was obtained as a method for accurately evaluating the stability of slag.
[0022]
That is, after the slag on the sieve classified by the first sieve is hydrated, the slag is sieved with the same first sieve and the slag particles under the sieve are observed in detail. It was found that relatively large slag grains that seemed to have not broken down were mixed in the slag that was broken by the treatment.
[0023]
The reason for this is that for the stability evaluation of these slags, fine particles are removed by classification treatment beyond the particle size required before the hydration promotion treatment, but all small slag is completely removed at this time. However, it is considered that some fine slag remained on the sieve and these slags fell under the sieve during classification after hydration promotion.
[0024]
Therefore, when the slag after the hydration promotion treatment is classified with the first sieve, and the sieve is further sieved with a second sieve smaller than the first sieve, the undisintegrated slag is apparently undissolved. As a result of being almost completely removed, only the slag that has collapsed by the hydration promotion treatment can be measured. By using this true decay rate, the decay rate is reduced if the original slag aging treatment is sufficient. Furthermore, it was clarified that this disintegration rate is closely related to the stability (destruction state) of the solidified body.
[0025]
FIG. 1 is a diagram showing the principle of the present invention. Here, as an example, in order to measure slag of 10 mm or more and 25 mm or less that has been aged in advance, the nominal dimensions (the length of one side of the mesh) 22.4 mm and 9.5 mm specified in JIS Z8801-1 Classify the slag in advance using sifter mesh. As the aging treatment, after standing in the atmosphere for at least one month, steam aging was performed at 180 ° C. for 6 hours as necessary.
[0026]
This slag is dried by performing hydration promotion treatment using hot water immersed in 80 ° C. (6 hours / day × 10 days) or autoclave (180 ° C. (about 20 atmospheres) × 6 hours). As in the case of classification with a 9.5 mm sieve mesh. However, under this sieving, there is still an uncollapsed and stable slag lump that must be sieved off during the previous classification process. Therefore, according to JIS Z8801-1, the slag under the above-mentioned 9.5 mm sieve is further classified using 8 mm, which is another one-stage sieve mesh (W3). In the figure, there is also shown an example in which the slag below the one-step small sieve is further sieved with a 2 mm sieve and separated into fragmentary slag and powdery slag (W2, W1).
[0027]
From this figure, according to the present invention, it is self-evident that the true collapse rate is indicated by the sum of the powder W1 and the fragmented slag amount W2 with respect to the original slag amount W0.
[0028]
However, conventionally, the sum of the powder (W1), the fragments (W2), and the undisintegrated slag (W3) is regarded as the decay rate. Of course, even if the prior classification is performed under certain conditions, it can be easily assumed that the slag W3 that should have been sieved out will vary during processing, which causes variations in measured values. The present inventors have found that.
[0029]
In addition, there is a case where the disintegration rate is considered as the disintegration rate by using only the powder W1 generated by the hydration treatment, as is partly reported as the powdering rate. The evaluation is much smaller than the true decay rate.
[0030]
Here, as a sieve used for classification, what is prescribed in the above-mentioned JIS Z 8801-1 is generally used in Japan. Furthermore, the final classification using a sieve smaller than the sieve used in the pre-classification process is a feature of the present invention. This includes a sieve having a size smaller by 1 to 2 stages as defined in JIS Z8801-1. It is preferable to use a slag having a small diameter, and a sieve mesh one step lower is sufficient. The prior classification process is generally performed with a large classifier, for example, but after the hydration promotion process, the amount of collapsed slag is small, and a low-tap tester is generally used to improve accuracy. Therefore, it is preferable in terms of measurement accuracy that the slag after the hydration promotion treatment is sufficiently dried to be classified for at least 3 minutes.
[0031]
As the hydration accelerating treatment of slag, JIS A5015 “steel slag for roads” “water immersion expansion test method” (10 days in hot water at 80 ° C.) or ASTM C151-08 which can be processed in a short time The method according to “Portland cement expansion test method” is generally used. In the latter case, sufficient data for evaluation can be obtained by treatment at 180 ° C. for 3 to 6 hours.
[0032]
Since the purpose of the present invention is to evaluate the slag disintegration rate after performing the aging treatment, after the aging treatment, to classify the undisintegrated slag, it is necessary to remove fine particles with the first sieve mesh. It is essential.
[0033]
Here, if the particle size of the original slag is 50 mm or less, preferably 25 mm or less, it is not necessary to classify the coarse particles in advance. On the other hand, if the particle size of the slag is more than 50 mm, preferably more than 25 mm, it is preferable to remove these coarse particles and use them for the hydration promotion treatment in order to avoid mixing the mixed metal.
[0034]
In addition, as the aging treatment, it is preferable that the digestive component is allowed to stand for 1 month or more at room temperature or for 6 hours or more under normal pressure or pressurized steam in order to cause hydration reaction. The effect of the present invention can be obtained without any particular limitation on the upper limit of the pressurization. However, in order to efficiently and economically obtain the hydration promoting effect of MgO, which has a particularly slow hydration reaction rate, it is 1 to 10 atm. It is preferable to process.
[0035]
Furthermore, the amount of slag used for the evaluation is not particularly limited, but the more the aging treatment is performed for the stabilization of the slag, the more the slag disintegration rate decreases. It is better to use at least 5kg.
[0036]
Some slags have a rocky surface, and some have a sandstone texture. Especially in the latter case, powder is formed. The measurement accuracy is better when the adhered powder is removed.
[0037]
【Example】
(Example of the present invention)
FIG. 2 shows a steelmaking slag stabilized by an aging treatment that is allowed to stand at room temperature for at least one month, and sieved with nominal sizes of 22.4 mm and 9.5 mm defined by JIS Z8801-1 (particle size range of 10 to 10). 25mm) 5kg is dried at 110 ° C for 24 hours after slag is soaked in hot water at 80 ° C for 10 days according to "Water immersion expansion test method" of JIS A5015 "Steel slag for road" 1 and classified using a sieve having a nominal size of 9.5 mm defined in JIS Z8801-1 by the method shown in FIG. 1, and the nominal size defined in JISZ8801-1 is defined under the sieve. Further classification with an 8 mm sieve, true breakage obtained by (slag mass under 8 mm sieve) / (10-25 mm slag mass before hydration promotion treatment) × 100% To confirm the stability of the solidified body (diameter: 100mm * height: 200mm) using the same slag as an aggregate and other blast furnace slag fine powder as the main binder It is the graph which showed the correlation with the destruction rate of the solidified body at the time of the acceleration evaluation (immersion for 4 weeks in 80 degreeC warm water). The fracture rate of the solidified body was determined by the number of samples disintegrated by accelerated evaluation / the number of samples used for evaluation.
[0038]
From this figure, when the true collapse rate of the slag according to the present invention exceeds about 3%, the solidified sample using the slag as an aggregate also breaks down, so that an aging treatment with a collapse rate of 3% or less was performed. Slag was found to be suitable as an aggregate for solidified bodies.
(Comparative Example 1)
FIG. 3 shows a steel slag stabilized by aging treatment that is allowed to stand at room temperature for at least one month, and sieved at nominal sizes of 22.4 mm and 9.5 mm as defined in JIS Z8801-1 (particle size range of 10 to 10). 25 mm) is packed into a container (mold) specified in “Water immersion expansion test method” as
[0039]
From this figure, even if the expansion coefficient which is the conventional evaluation method is used, the solidified body using the slag is broken or not broken when it is in the range of 0.3% or more. It was not possible to find a suitable slag condition.
(Comparative Example 2)
FIG. 4 shows a steel slag stabilized by an aging treatment that is allowed to stand at room temperature for at least one month, and sieved at nominal sizes of 22.4 mm and 9.5 mm defined by JIS Z8801-1 (particle size range of 10 to 10). 25mm) 5kg is dried at 110 ° C for 24 hours after slag is soaked in hot water at 80 ° C for 10 days according to "Water immersion expansion test method" of JIS A5015 "Steel slag for road" Then, when classification is performed with a sieve having a nominal size of 9.5 mm as defined in JIS Z 8801-1 as used in the previous classification process (slag mass under a sieve of 9.5 mm) / (acceleration of hydration) 10-25mm slag mass before processing) x 100%, so-called collapse rate so far, and the slag is used as an aggregate and other blast furnace slag fine powder As a slag, a solidified body (
[0040]
From this figure, the slag decay rate according to the conventional method is mixed with partially uncollapsed slag grains as described above, so that when the decay rate is in the range of 2% or more, Comparative Example 1 Similarly, the solidified body using the slag was broken or not broken, and the slag conditions suitable for the stable solidified body could not be found.
[0041]
【The invention's effect】
According to the present invention, when steel slag, particularly steelmaking slag having a digestible component and having a property of expanding over a long period of time, is used for a new application such as a solidified material other than for roads, an aging treatment is performed. It is possible to accurately evaluate the stability of the slag that has been applied and stabilized.
[Brief description of the drawings]
FIG. 1 is a diagram showing the principle of the present invention.
FIG. 2 is a diagram showing a relationship between a collapse rate of slag according to the present invention and a fracture rate of a solidified body using the slag as an aggregate.
FIG. 3 is a diagram showing the relationship between the expansion rate of slag according to the prior art and the fracture rate of a solidified body using the slag as an aggregate.
FIG. 4 is a diagram showing a relationship between a collapse rate of slag according to a conventional technique and a fracture rate of a solidified body using the slag as an aggregate.
Claims (6)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003095404A JP4274834B2 (en) | 2003-03-31 | 2003-03-31 | Slag stability evaluation method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003095404A JP4274834B2 (en) | 2003-03-31 | 2003-03-31 | Slag stability evaluation method |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2004301686A JP2004301686A (en) | 2004-10-28 |
JP4274834B2 true JP4274834B2 (en) | 2009-06-10 |
Family
ID=33407740
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2003095404A Expired - Lifetime JP4274834B2 (en) | 2003-03-31 | 2003-03-31 | Slag stability evaluation method |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP4274834B2 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105300795B (en) * | 2014-06-18 | 2018-02-02 | 上海宝冶钢渣综合开发实业有限公司 | A kind of detection method of slag product stability |
CN108642224B (en) * | 2018-05-15 | 2020-06-23 | 鞍钢股份有限公司 | Method for modifying converter slag by using blast furnace slag and molten iron |
CN110411795B (en) * | 2019-06-21 | 2020-06-30 | 中国矿业大学 | Method for simulating equivalent field soft coal in laboratory |
JP7323747B2 (en) * | 2019-07-04 | 2023-08-09 | 濱田重工株式会社 | Method for evaluating hydration expansion behavior of steelmaking slag and steam aging apparatus |
CN113466079B (en) * | 2021-06-30 | 2023-05-16 | 重庆钢铁股份有限公司 | Method for detecting content of steel slag components |
-
2003
- 2003-03-31 JP JP2003095404A patent/JP4274834B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JP2004301686A (en) | 2004-10-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Johnson et al. | The efficacy of accelerated test methods to evaluate alkali silica reactivity of recycled concrete aggregates | |
JP2004292295A (en) | Hardened body of slag | |
Muhit et al. | Influence of crushed coarse aggregates on properties of concrete | |
Danko | Experiences gathered during reclamation of used water glass and bentonite sands in extra low and ambient temperature | |
Cyr et al. | Reduction of ASR-expansion using powders ground from various sources of reactive aggregates | |
Pichelin et al. | Sustainability, transfer and containment properties of concrete subject to delayed ettringite formation (DEF) | |
Fu et al. | Internal pore evolution and early hydration characterization of fly ash cement backfill | |
JP4274834B2 (en) | Slag stability evaluation method | |
Mohammed1a et al. | Utilization of steel slag in concrete as coarse aggregate | |
Li et al. | Microstructure of pretreated steel slag and its influence on mechanical properties of cement stabilized mixture | |
Tang et al. | Effect of carbonation treatment on fracture behavior of low-carbon mortar with recycled sand and recycled powder | |
JP4274835B2 (en) | Slag stability evaluation method | |
JP2010013315A (en) | Manufacturing method of civil engineering material using steel slag | |
JP4357199B2 (en) | Slag stability evaluation method | |
JP5157639B2 (en) | Expandability evaluation method for sorting roadbed materials | |
Onoue et al. | Fatigue characteristics of steel-making slag concrete under compression in submerged condition | |
Adams et al. | Applicability of standard alkali-silica reactivity testing methods for recycled concrete aggregate | |
KR100979005B1 (en) | A mortar method used recycled aggregates and mortar thereof | |
Humbert et al. | Elastic modulus and stress-strain curve analysis of a tungsten mine waste alkali-activated concrete | |
Olatoyan et al. | Investigation of tensile strength performance of green concrete incorporating steel slag | |
CN111189705A (en) | Method for rapidly detecting activity of solid waste applied to building material | |
JP2015189643A (en) | Sorting method for steel slag, steel slag and sorting apparatus for steel slag | |
KR100419621B1 (en) | Manufacturing method of concrete aggregate having excellent compressive strength | |
Demir Şahin | Evaluation of Cherts in Gumushane Province in Terms of Alkali Silica Reaction | |
Turgunbayeva et al. | Investigation of mechanical activation of steelmaking slag and obtaining fine filler |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060224 |
|
TRDD | Decision of grant or rejection written | ||
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20090203 |
|
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20090303 |
|
R151 | Written notification of patent or utility model registration |
Ref document number: 4274834 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R151 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120313 Year of fee payment: 3 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130313 Year of fee payment: 4 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130313 Year of fee payment: 4 |
|
S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130313 Year of fee payment: 4 |
|
S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130313 Year of fee payment: 4 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130313 Year of fee payment: 4 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140313 Year of fee payment: 5 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
EXPY | Cancellation because of completion of term |