JP2012017504A - Method for suppressing heat dissipation of molten iron - Google Patents
Method for suppressing heat dissipation of molten iron Download PDFInfo
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- JP2012017504A JP2012017504A JP2010156049A JP2010156049A JP2012017504A JP 2012017504 A JP2012017504 A JP 2012017504A JP 2010156049 A JP2010156049 A JP 2010156049A JP 2010156049 A JP2010156049 A JP 2010156049A JP 2012017504 A JP2012017504 A JP 2012017504A
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- 238000000034 method Methods 0.000 title claims abstract description 51
- 230000017525 heat dissipation Effects 0.000 title claims abstract description 35
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title abstract description 28
- 229910052742 iron Inorganic materials 0.000 title abstract description 14
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 96
- 239000000292 calcium oxide Substances 0.000 claims abstract description 48
- 235000012255 calcium oxide Nutrition 0.000 claims abstract description 48
- 239000002893 slag Substances 0.000 claims abstract description 30
- 239000011248 coating agent Substances 0.000 claims abstract description 27
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 21
- 230000023556 desulfurization Effects 0.000 claims abstract description 21
- 239000002184 metal Substances 0.000 claims description 112
- 229910052751 metal Inorganic materials 0.000 claims description 112
- 230000008569 process Effects 0.000 claims description 21
- 239000011810 insulating material Substances 0.000 abstract 2
- 239000003795 chemical substances by application Substances 0.000 description 23
- 230000007423 decrease Effects 0.000 description 11
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- 229910052799 carbon Inorganic materials 0.000 description 8
- 239000010455 vermiculite Substances 0.000 description 8
- 229910052902 vermiculite Inorganic materials 0.000 description 8
- 235000019354 vermiculite Nutrition 0.000 description 8
- 238000007670 refining Methods 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 230000001629 suppression Effects 0.000 description 6
- 230000002411 adverse Effects 0.000 description 4
- 238000005261 decarburization Methods 0.000 description 4
- 238000009413 insulation Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
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- 239000002904 solvent Substances 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000011449 brick Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 235000020083 shōchū Nutrition 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
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- 238000003756 stirring Methods 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- 238000002485 combustion reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010903 husk Substances 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
Description
本発明は、溶銑の脱硫後に脱燐を行う溶銑予備処理プロセスにおいて、溶銑を脱硫した後に、特別な保温剤を使用せず、次工程で使用する生石灰を溶銑の表面に添加することによって、取鍋中に格納された溶銑の表面からの放熱を抑制する方法に関するものである。 The present invention is a hot metal pretreatment process in which dephosphorization is performed after desulfurization of hot metal, and after desulfurizing the hot metal, a special heat retention agent is not used, and quick lime used in the next step is added to the surface of the hot metal. The present invention relates to a method for suppressing heat dissipation from the surface of hot metal stored in a pan.
鉄鋼の溶銑予備処理では、除去した成分が溶銑中に再移行することを防止する観点から、処理後のスラグを速やかに除去している。このため、溶銑表面からの放熱が大きくなって追加の熱源が必要となる。また、取鍋中に格納した溶銑の滞留時間が長くなると、溶銑の表面が固化して操業の妨げとなる場合がある。 In the hot metal preliminary treatment of iron and steel, the slag after the treatment is quickly removed from the viewpoint of preventing the removed components from re-transferring into the hot metal. For this reason, the heat radiation from the hot metal surface is increased, and an additional heat source is required. Moreover, when the residence time of the hot metal stored in the ladle becomes long, the surface of the hot metal may solidify and hinder the operation.
このため、鉄鋼の溶銑予備処理では、溶銑表面からの放熱を抑制することが課題であり、種々の提案がなされている。 For this reason, in hot metal preliminary processing of steel, it is a subject to control heat dissipation from the hot metal surface, and various proposals have been made.
例えば特許文献１では、Al、 Si、 C、及びバーミュキライトや焼籾殻を添加した溶銑温度降下防止剤が提案されている。 For example, Patent Document 1 proposes a hot metal temperature drop preventive agent to which Al, Si, C, vermiculite or shochu shell is added.
この特許文献１で提案された溶銑温度降下防止剤は、Al、 Si、 Cの燃焼発熱反応を利用するので高い保温効果が得られるものの、金属AlやSiを含有するのでコストが高くなる。また、Siは酸化反応によりSiO2となるので、次の脱燐工程或いは脱炭工程において、目標とするスラグ塩基度（CaO／SiO2）に応じて生石灰を追加する必要があり、コスト及び廃棄物の増大を招くという問題がある。 Although the hot metal temperature drop preventing agent proposed in Patent Document 1 uses a combustion exothermic reaction of Al, Si, and C to obtain a high heat retention effect, it contains metal Al or Si, and therefore costs are increased. In addition, since Si becomes SiO 2 due to an oxidation reaction, it is necessary to add quick lime according to the target slag basicity (CaO / SiO 2 ) in the next dephosphorization process or decarburization process. There is a problem that it causes an increase in things.
バーミュキライトや焼籾殻を単体で添加しても保温効果はあるが、これらは保温効果を得るためだけに用いるものであり、次工程あるいは本工程における媒溶剤としての効果はない。このため、必要なコストが高くなり、また、バーミュキライトや焼籾殻の温度上昇に溶銑の保有する熱量が取られるという問題もある。また、バーミュキライトは融点が低く、滓化するので、対流が生成し輻射熱が増加するという問題もある。 Even if vermiculite or shochu husk is added alone, there is a heat retention effect, but these are used only to obtain a heat retention effect, and have no effect as a solvent in the next step or this step. For this reason, a necessary cost becomes high, and there is also a problem that the amount of heat possessed by the hot metal is taken for the temperature rise of vermiculite and shochu shell. In addition, vermiculite has a low melting point and hatches, so there is a problem that convection is generated and radiant heat increases.
また、特許文献２では、使用済のMgO−C煉瓦を破砕し、保温剤として用いてそのまま転炉に装入する方法が提案されている。 Further, Patent Document 2 proposes a method in which used MgO-C brick is crushed and used as a heat insulating agent and directly charged into a converter.
しかしながら、転炉或いは転炉型脱燐処理において、スラグ中のMgO濃度が好適点である１０質量%以下よりも高くなると、スラグ粘度が著しく上昇して排滓性が低下し、また、局所的なT.Fe増大による耐火物溶損等の問題がある。このため、使用済MgO−C煉瓦屑の使用量が制限され、十分な保温効果が得られない。また、MgO−C煉瓦は、Cを含有するので比較的熱伝導度が高く、溶銑表面からの放熱抑制には十分な効果が得られないという問題もある。 However, when the MgO concentration in the slag is higher than 10% by mass or less, which is a suitable point, in the converter or the converter type dephosphorization process, the slag viscosity is remarkably increased and the evacuation property is lowered. There is a problem of refractory melting due to an increase in T.Fe. For this reason, the usage-amount of used MgO-C brick waste is restrict | limited, and sufficient heat retention effect is not acquired. Further, since MgO-C brick contains C, it has a relatively high thermal conductivity, and there is a problem that a sufficient effect cannot be obtained for suppressing heat dissipation from the hot metal surface.
また、特許文献３では、溶銑脱燐−溶銑脱硫−溶銑脱炭の順で行う溶銑予備処理プロセスにおいて、溶銑脱燐後に脱燐処理を行った後のスラグを除去しないことで、スラグを溶銑の放熱抑制剤として使用する方法が提案されている。 Moreover, in patent document 3, in the hot metal preliminary treatment process performed in the order of hot metal dephosphorization-hot metal desulfurization-hot metal decarburization, the slag is removed by not removing the slag after the dephosphorization treatment after the hot metal dephosphorization. A method for use as a heat dissipation inhibitor has been proposed.
この特許文献３で提案された方法は、特別な保温剤を使用する必要がないので、保温剤コストが不要になるという利点を有している。 The method proposed in Patent Document 3 does not require the use of a special heat insulating agent, and therefore has the advantage that the heat insulating agent cost is not required.
しかしながら、当該工程の溶銑脱燐は酸化精錬であるため、スラグにはFeOやMnOといった酸性の酸化物が大量に含まれ、次工程の脱硫効率を低下させるという課題を有する。また、FeOやMnOの存在下では、生石灰の融点が低下して融解するために、放熱抑制という目的からは望ましくない。加えて、本願が対象とする溶銑脱硫−溶銑脱燐−溶銑脱炭の順で行う溶銑予備処理プロセスには適用することができない。 However, since the hot metal dephosphorization in this process is oxidative refining, the slag contains a large amount of acidic oxides such as FeO and MnO, and there is a problem that the desulfurization efficiency in the next process is lowered. Further, in the presence of FeO or MnO, the melting point of quicklime is lowered and melted, which is not desirable for the purpose of suppressing heat dissipation. In addition, it cannot be applied to the hot metal pretreatment process performed in the order of hot metal desulfurization, hot metal dephosphorization, hot metal decarburization, which is the subject of the present application.
さらに、特許文献４でも、前記特許文献３で提案された方法と同じ順序の溶銑予備処理プロセスにおいて、転炉型容器において溶銑脱燐を行った後、中間容器に出湯する際に、金属Al、或いは炭素濃度が７０質量%以上の炭素含有物質と共に１〜１０kg／溶銑tonの生石灰を添加する方法が提案されている。 Further, even in Patent Document 4, in the hot metal preliminary treatment process in the same order as the method proposed in Patent Document 3, after performing hot metal dephosphorization in a converter type vessel, when pouring hot water into an intermediate vessel, metal Al, Alternatively, a method of adding 1 to 10 kg / ton hot metal lime together with a carbon-containing material having a carbon concentration of 70% by mass or more has been proposed.
この特許文献４で提案された方法は、前記特許文献３で提案された方法に比べ、次工程の脱硫効率を低下させない点で優れている。 The method proposed in Patent Document 4 is superior to the method proposed in Patent Document 3 in that the desulfurization efficiency in the next step is not lowered.
しかしながら、金属Alや炭素濃度７０質量%以上の炭素含有物質のような、追加の熱源を必要とする点は、コストアップを引き起こすので必ずしも望ましくない。加えて、脱燐スラグが流出した場合、金属Alや炭素と混合することで復燐を生ずることから、極低燐鋼の製造には必ずしも適していない。また、金属Alや炭素含有物質と共に生石灰を添加していることから、攪拌を伴う出湯時に生石灰が融解するため、放熱抑制という目的では望ましくない。 However, the need for an additional heat source, such as metal Al or a carbon-containing material having a carbon concentration of 70% by mass or more, is not always desirable because it causes an increase in cost. In addition, when dephosphorization slag flows out, it is not necessarily suitable for the production of ultra-low phosphorous steel because it is recovered by mixing with metal Al or carbon. Moreover, since quick lime is added with metal Al and a carbon containing substance, since quick lime melts at the time of the hot water accompanied by stirring, it is not desirable for the purpose of suppressing heat dissipation.
また、特許文献５では、溶銑運搬装置として、溶銑鍋の上に保温蓋を設置して放熱を抑制する技術が提案されている。 Moreover, in patent document 5, the technique which installs a thermal insulation cover on a hot metal ladle and suppresses heat radiation as a hot metal conveyance apparatus is proposed.
しかしながら、この特許文献５で提案された技術は、保温蓋の開閉装置を必要とするため、設置するには大掛かりな設備改造が必要である。また、比較的低温処理となる溶銑予備処理工程では、溶銑鍋に地金やスラグが付着し、保温蓋が装着できないという問題がある。 However, since the technique proposed in Patent Document 5 requires an opening / closing device for a heat insulating lid, a large-scale facility modification is required for installation. In addition, in the hot metal preliminary treatment process, which is a relatively low temperature treatment, there is a problem that metal or slag adheres to the hot metal pan and the heat insulating lid cannot be attached.
本発明が解決しようとする問題点は、従来の技術は、大掛かりな設備を設置する必要があったり、保温剤コストが増大したり、或いは保温剤使用に伴うスラグ量の増大やMgO濃度の上昇といった次工程への悪影響があるという点である。 The problems to be solved by the present invention are that the conventional technology requires the installation of large-scale equipment, the cost of the heat insulation agent increases, the amount of slag accompanying the use of the heat insulation agent, or the increase in MgO concentration There is an adverse effect on the next process.
本発明は、大掛かりな設備を設置する必要がなく、また保温剤コストが増大せず、さらには保温剤使用に伴うスラグ量の増大やMgO濃度の上昇といった次工程に悪い影響を及ぼすことのない溶銑の放熱抑制方法の提供を目的とするものである。 The present invention does not require the installation of large-scale equipment, does not increase the cost of the heat insulating agent, and does not adversely affect the next process such as an increase in the amount of slag accompanying the use of the heat insulating agent and an increase in the MgO concentration. The object is to provide a method for suppressing the heat dissipation of hot metal.
本発明の溶銑の放熱抑制方法は、溶銑脱硫−溶銑脱燐の順序で予備処理を行う工程における溶銑の放熱抑制方法であって、溶銑の脱硫処理後、脱硫処理に使用したスラグを除去した後に、原単位で０．３kg／ton〜１．０kg／tonの生石灰を溶銑の表面に添加することを最も主要な特徴としている。 The method for suppressing heat dissipation of hot metal of the present invention is a method for suppressing heat dissipation of hot metal in a process of performing pretreatment in the order of hot metal desulfurization-hot metal dephosphorization, and after removing slag used for desulfurization treatment after desulfurization of hot metal. The most important feature is the addition of quick lime in a basic unit of 0.3 kg / ton to 1.0 kg / ton to the surface of the hot metal.
上記本発明の溶銑の放熱抑制方法では、溶銑の脱硫処理に使用したスラグを除去した後に、精錬剤に使用する生石灰を溶銑の表面に所定量添加して、溶銑の放熱を抑制するので、大掛かりな設備を設置する必要がなく、また保温剤コストが増大することもない。また、保温剤使用に伴うスラグ量の増大やMgO濃度の上昇といった次工程に悪い影響を及ぼすこともない。 In the hot metal heat dissipation suppression method of the present invention, after removing the slag used for the hot metal desulfurization treatment, a predetermined amount of quick lime used for the refining agent is added to the surface of the hot metal to suppress the heat dissipation of the hot metal. It is not necessary to install a new facility and the cost of the heat insulating agent does not increase. Moreover, it does not adversely affect the next process such as an increase in the amount of slag accompanying the use of the heat insulating agent and an increase in the MgO concentration.
上記構成の本発明の溶銑の放熱抑制方法において、表面被覆剤として投入した前記生石灰は、次工程の溶銑脱燐処理において精錬剤としてそのまま使用できるので、その添加量を所定の生石灰添加量から減量すれば、次工程での投入量を減少することができる。 In the hot metal heat dissipation suppression method of the present invention having the above-described configuration, the quick lime introduced as a surface coating agent can be used as it is as a refining agent in the hot metal dephosphorization process in the next step, so that the amount added is reduced from the predetermined amount of quick lime added. If so, the input amount in the next step can be reduced.
本発明によれば、特別な表面被覆剤を使用することなく、溶銑予備処理後の放熱を抑制することができる。これに伴い、溶銑温度の低下を３．５℃〜２２℃程度抑制でき、鉄歩留りを０．０３%〜０．２２%程度高めることができた。 According to the present invention, it is possible to suppress heat dissipation after the hot metal preliminary treatment without using a special surface coating agent. Along with this, a decrease in hot metal temperature could be suppressed by about 3.5 ° C. to 22 ° C., and the iron yield could be increased by about 0.03% to 0.22%.
本発明では、大掛かりな設備を必要とせず、また保温剤コストを増大させず、さらには保温剤使用に伴うスラグ量の増大やMgO濃度の上昇といった次工程に悪い影響を及ぼすことがないようにするという目的を、溶銑脱硫処理に使用したスラグの除去後に、精錬剤に使用する生石灰を所定量添加することによって実現した。 The present invention does not require large-scale equipment, does not increase the cost of the heat insulating agent, and does not adversely affect the next process such as an increase in the amount of slag and the increase in MgO concentration due to the use of the heat insulating agent. This purpose was realized by adding a predetermined amount of quicklime used as a refining agent after the removal of slag used in hot metal desulfurization treatment.
以下、本発明の課題解決に至るまでの過程を説明した後に、本発明の溶銑の放熱抑制方法について説明する。 Hereinafter, after explaining the process up to the solution of the problem of the present invention, the method for suppressing heat dissipation of hot metal of the present invention will be described.
溶銑は、主として容器の開放部からの放射によって放熱する。従って、溶銑の放熱を抑制するには、(1) 容器の開放部の表面積を小さくすること、(2) 溶銑の露出表面の温度を低下させて熱放射を抑制すること、が有効である。 The hot metal dissipates heat mainly by radiation from the open part of the container. Therefore, in order to suppress the heat dissipation of the hot metal, it is effective to (1) reduce the surface area of the open portion of the container and (2) reduce the temperature of the exposed surface of the hot metal to suppress thermal radiation.
(1) の対策については、特許文献５で提案された保温蓋を設置する方法があるが、温度が低く地金或いはスラグの付着が多い溶銑鍋では、その開放部を密閉することが困難である。また、保温蓋脱着装置の設備費が膨大であるという問題もある。 As for the countermeasure of (1), there is a method of installing a heat insulating lid proposed in Patent Document 5, but it is difficult to seal the open part of a hot metal ladle where the temperature is low and the adhesion of metal or slag is large. is there. In addition, there is a problem that the equipment cost of the heat insulating lid attaching / detaching device is enormous.
また、(2) の溶銑の露出表面の温度を低下させる方法としては、溶銑以外の物質、特に熱伝導率の低い非金属製の物質で溶銑の表面を被覆することが挙げられる。表面被覆剤に求められる性質は、熱伝導率が低いほど、また表面被覆剤の厚みが大きいほど、溶銑の露出表面の温度が低下することから、特許文献１で提案された溶銑温度降下防止剤に使用される嵩比重の小さいバーミュキライトや、スラグ分を含んだ表面被覆剤が用いられてきた。 In addition, as the method (2) for reducing the temperature of the exposed surface of the hot metal, the surface of the hot metal may be coated with a material other than the hot metal, particularly a non-metallic material with low thermal conductivity. The property required for the surface coating agent is that the temperature of the exposed surface of the hot metal decreases as the thermal conductivity is lower and the thickness of the surface coating agent is larger. For example, vermiculite having a small bulk specific gravity and a surface coating agent containing slag have been used.
これらの表面被覆剤はコストを要すると共に、比較的融点が低く、添加時に融解する場合がある。表面被覆剤が融解すると、流動性が増し、また体積が小さくなる。表面被覆剤の流動性向上は、取鍋の測温やサンプリングを妨げるスラグの固化を防止するという観点からは望ましい。しかしながら、対流による放熱、また体積減少による断熱効果の低下が生じ、本願発明が対象とするような溶銑自体の皮張り防止、或いは放熱抑制という観点からは望ましくない。 These surface coating agents are costly and have a relatively low melting point and may melt upon addition. When the surface coating melts, the fluidity increases and the volume decreases. The improvement of the fluidity of the surface coating agent is desirable from the viewpoint of preventing the slag from solidifying which disturbs the temperature measurement and sampling of the ladle. However, heat dissipation due to convection and a decrease in heat insulation effect due to volume reduction occur, which is not desirable from the viewpoint of preventing skinning of the hot metal itself or suppressing heat dissipation as the subject of the present invention.
ところで、一般的な製鋼プロセスでは、脱燐や脱硫といった溶銑予備処理を施した後、当該処理に用いたスラグを除去し、さらに他の溶銑予備処理或いは転炉で脱炭処理を行う。 By the way, in a general steelmaking process, after hot metal pretreatment such as dephosphorization and desulfurization is performed, the slag used in the treatment is removed, and further decarburization treatment is performed in another hot metal pretreatment or converter.
これらの次工程の処理には、CaO（生石灰）を含む精錬剤が主に使用される。生石灰は嵩比重が１．０〜２．０程度と大きいので、溶銑の表面被覆剤として望ましい性質を持つ。また、生石灰は融点が２５７２℃と高く、融解による嵩比重の低下や流動性の増加が起こり難い。 A refining agent containing CaO (quick lime) is mainly used for the processing of these next steps. Quick lime has a large bulk specific gravity of about 1.0 to 2.0, and therefore has desirable properties as a hot metal surface coating agent. Quicklime has a high melting point of 2572 ° C., and it is difficult for a decrease in bulk specific gravity and an increase in fluidity due to melting.
発明者らは、この特性を利用し、脱硫処理後にスラグを除去した溶銑の表面に生石灰を添加することで、放熱を抑制できることを知見した。また、添加した生石灰を次工程の脱燐処理の精錬剤としてそのまま使用した場合は、次工程での投入量を減少することができ、このため保温剤或いは表面被覆剤に要するコストを必要とせずに放熱抑制が可能であることも知見した。 The inventors have found that heat dissipation can be suppressed by adding quick lime to the surface of the hot metal from which slag has been removed after the desulfurization treatment using this characteristic. In addition, when the added quicklime is used as it is as a refining agent for the dephosphorization process in the next step, the input amount in the next step can be reduced, so that the cost required for the heat retaining agent or the surface coating agent is not required. It was also found that heat dissipation can be suppressed.
本発明の溶銑の放熱抑制方法は、上記の知見に基づいてなされたものであり、溶銑脱硫−溶銑脱燐の順序で予備処理を行う工程における溶銑の放熱抑制方法であって、溶銑の脱硫処理後、脱硫処理に使用したスラグを除去した後に、所定量の生石灰を溶銑の表面に添加することとしている。 The method for suppressing heat dissipation of hot metal according to the present invention is based on the above knowledge, and is a method for suppressing heat dissipation of hot metal in the process of performing pretreatment in the order of hot metal desulfurization-hot metal dephosphorization, Then, after removing the slag used for the desulfurization treatment, a predetermined amount of quicklime is added to the surface of the hot metal.
この結果、本発明の溶銑の放熱抑制方法では、溶銑の放熱抑制、溶銑表面の皮張り抑制を、特別な保温剤を使用することなく行うことができる。 As a result, in the hot metal heat dissipation suppression method of the present invention, it is possible to suppress the heat dissipation of the hot metal and the skin surface of the hot metal without using a special heat retention agent.
次に、上記本発明の溶銑の放熱抑制方法において、溶銑の表面に添加する生石灰の最適量とその効果を調査するために行った実験結果について説明する。 Next, in the method for suppressing heat dissipation of hot metal according to the present invention, the optimum amount of quicklime added to the surface of the hot metal and the results of experiments conducted to investigate the effect will be described.
高炉からトーピードカーにて搬送した２５０トンの溶銑を溶銑鍋に払い出し、溶銑鍋中の溶銑に生石灰等の媒溶剤を添加し、機械式撹拌装置で攪拌して脱硫処理を行い、その後復硫を防止するために脱硫スラグを除去した。 Dispense 250 tons of hot metal transported from a blast furnace with a torpedo car to the hot metal ladle, add a medium solvent such as quick lime to the hot metal in the hot metal ladle, and stir it with a mechanical stirrer to prevent desulfurization. The desulfurized slag was removed.
この脱硫スラグを除去した溶銑の表面に、下記表１に示した表面被覆剤を溶銑鍋の上方から添加した。その後、予めスクラップを投入した転炉型脱燐処理炉に溶銑鍋から溶銑を装入し、これに生石灰等の媒溶剤を加え、炉底から不活性ガスを吹込んで撹拌しながら、溶銑上部から酸素を吹き付けて脱燐処理を行った。なお、表面被覆剤として生石灰を使用したものは、その量に応じて脱燐処理炉で添加する生石灰の量を減量した。 The surface coating agent shown in Table 1 below was added from above the hot metal ladle to the hot metal surface from which the desulfurized slag was removed. After that, hot metal is charged from the hot metal ladle into the converter type dephosphorization processing furnace into which scrap has been charged in advance, a medium solvent such as quick lime is added thereto, and an inert gas is blown from the bottom of the furnace while stirring, from above the hot metal. Dephosphorization treatment was performed by blowing oxygen. In addition, what used quicklime as a surface coating agent reduced the quantity of the quicklime added with a dephosphorization processing furnace according to the quantity.
脱硫スラグ除去後と脱燐処理後の間の溶銑温度・成分の差違及び脱燐処理で投入したスクラップ・媒溶剤の冷却能を合算して温度換算をし、脱硫スラグ除去から脱燐処理までの時間と放熱量をプロットすることで、時間当たりの温度低下量を評価した。 The temperature is converted by adding the difference in hot metal temperature and components between the desulfurization slag removal and after the dephosphorization treatment, and the cooling capacity of the scrap and solvent added in the dephosphorization treatment, from desulfurization slag removal to dephosphorization treatment. By plotting the time and the amount of heat release, the amount of temperature decrease per hour was evaluated.
図１に表１に示した表面被覆剤毎の時間当たりの温度低下量を示したが、時間当たりの温度低下速度は、生石灰を表面被覆材として使用した場合が一番遅いことが分かる。 FIG. 1 shows the amount of temperature decrease per hour for each surface coating agent shown in Table 1. It can be seen that the rate of temperature decrease per hour is the slowest when quick lime is used as the surface coating material.
下記表２は、前記表１に示した表面被覆材を、生石灰では０．３〜１．０kg／ton（厚み換算で６〜２１mm）、バーミュキライトでは０．１１〜０．１５kg／ton（厚み換算で１５〜２１mm）添加して２０〜１３０分保持した場合の、温度低下量及び溶銑表面の固化の有無を調査した結果の一例を示したものである。 Table 2 below shows the surface coating materials shown in Table 1 in the range of 0.3 to 1.0 kg / ton (6 to 21 mm in terms of thickness) for quicklime and 0.11 to 0.15 kg / ton for vermiculite. It shows an example of the result of investigating the amount of temperature decrease and the presence or absence of solidification of the hot metal surface when added (15 to 21 mm in terms of thickness) and held for 20 to 130 minutes.
なお、脱燐処理で使用する生石灰量は、通常は７．０kg／ton〜２０．０kg／tonであるところ、本発明の実施においては、６．０kg／ton〜１９．７kg／tonと、表面被覆剤として生石灰を使用した量に応じて生石灰の添加量を減量した。 The amount of quicklime used in the dephosphorization treatment is usually 7.0 kg / ton to 20.0 kg / ton, but in the practice of the present invention, 6.0 kg / ton to 19.7 kg / ton, The amount of quicklime added was reduced according to the amount of quicklime used as the coating agent.
その結果、特別な表面被覆剤コストを要することなく、生石灰を表面被覆剤として使用した場合、表面被覆剤を使用しなかった場合と比較して、温度低下量は１／４に抑制できた。また、バーミュキライトを表面被覆剤として使用した場合と比較しても温度低下量は４１％減少した。 As a result, without using a special surface coating agent cost, when quick lime was used as the surface coating agent, the amount of temperature decrease could be suppressed to ¼ compared to the case where the surface coating agent was not used. Further, the amount of temperature decrease was reduced by 41% even when vermiculite was used as a surface coating agent.
また、表面被覆剤である生石灰の添加量を変化させた場合の、生石灰の添加量と温度低下量との関係を図２に示す。 Moreover, the relationship between the addition amount of quick lime and the amount of temperature fall at the time of changing the addition amount of quick lime which is a surface coating agent is shown in FIG.
図２より、生石灰の添加量が０．３０kg／溶銑ton未満の場合は、放熱抑制効果が著しく低下していることが分かる。これは、生石灰は溶銑予備処理温度である１２００℃〜１４００℃の領域では単体では溶融せず溶銑表面に一様に広がらないことから、溶銑が露出する部分が生じ、この部分からの放熱量が大きかったことによると考えられる。 FIG. 2 shows that when the amount of quicklime added is less than 0.30 kg / molten iron ton, the effect of suppressing heat release is significantly reduced. This is because quick lime does not melt by itself in the hot metal pretreatment temperature range of 1200 ° C. to 1400 ° C. and does not spread uniformly on the hot metal surface. It is thought that it was because it was big.
一方、生石灰の添加量が１．０kg／溶銑tonを超えても放熱抑制効果は大きく変化しなかった。これは、１．０kg／溶銑tonを超える場合は、生石灰の表面温度が十分低下し、放熱抑制効果が飽和したためと考えられる。 On the other hand, even if the addition amount of quicklime exceeded 1.0 kg / molten iron ton, the heat dissipation suppression effect did not change greatly. This is considered to be because when the amount exceeds 1.0 kg / ton of hot metal, the surface temperature of quicklime is sufficiently lowered, and the heat dissipation suppression effect is saturated.
表２及び図２より、添加原単位で０．３０kg／溶銑ton以上、１．０kg／溶銑ton以下の生石灰を溶銑の上方から投入して溶銑の表面を被覆することで、バーミュキライト等の保温剤を使用する場合と比較して、放熱量を大きく低減することが可能であることが判明した。加えて、表面被覆材として精錬剤に使用する生石灰を使用すれば、次工程の生石灰使用量を削減することができ、特別な保温剤コストも不要となる。 From Table 2 and Fig. 2, by adding raw lime of 0.30kg / molten iron ton or 1.0kg / tonn or less from the top of the hot metal to cover the hot metal surface, vermiculite, etc. It was found that the amount of heat release can be greatly reduced as compared with the case of using the heat retaining agent. In addition, if quick lime used for the refining agent is used as the surface covering material, the amount of quick lime used in the next step can be reduced, and a special heat retention cost is not required.
本発明は、上記の知見及び実験結果に基づいて成されたものであり、溶銑脱硫−溶銑脱燐の順序で予備処理を行う工程における溶銑の放熱抑制方法であって、溶銑の脱硫処理後、脱硫処理に使用したスラグを除去した後に、原単位で０．３kg／ton〜１．０kg／tonの生石灰を溶銑の表面に添加することを特徴とするものである。 The present invention was made on the basis of the above knowledge and experimental results, and is a method for suppressing heat dissipation of hot metal in the step of performing pretreatment in the order of hot metal desulfurization-hot metal dephosphorization, and after desulfurization treatment of hot metal, After removing the slag used for the desulfurization treatment, 0.3 kg / ton to 1.0 kg / ton of quick lime is added to the surface of the hot metal as a basic unit.
また、本発明の溶銑の放熱抑制方法は、溶銑の脱硫処理後の溶銑脱燐処理において、前記生石灰をそのまま使用すべく、表面被覆剤として投入した前記生石灰の添加量を所定の生石灰添加量から減量することを特徴とするものである。 The hot metal heat dissipation suppression method of the present invention is the hot metal dephosphorization treatment after the hot metal desulfurization treatment, in order to use the quick lime as it is, the amount of quick lime added as a surface coating agent from the predetermined quick lime addition amount It is characterized by weight loss.
本発明は上記の例に限らず、各請求項に記載された技術的思想の範疇であれば、適宜実施の形態を変更しても良いことは言うまでもない。 The present invention is not limited to the above example, and it goes without saying that the embodiments may be changed as appropriate within the scope of the technical idea described in each claim.
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| JPH06108136A (en) * | 1992-09-29 | 1994-04-19 | Kobe Steel Ltd | Production of low p and low s foundry pig iron |
| JP2005139528A (en) * | 2003-11-10 | 2005-06-02 | Nippon Steel Corp | Method for dephosphorization-refining molten pig iron |
| JP2008063645A (en) * | 2006-09-11 | 2008-03-21 | Jfe Steel Kk | Steelmaking method |
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| JPS61194107A (en) * | 1985-02-25 | 1986-08-28 | Kawasaki Steel Corp | Method for effectively utilizing quick lime in steel manufacturing process |
| JPH06108136A (en) * | 1992-09-29 | 1994-04-19 | Kobe Steel Ltd | Production of low p and low s foundry pig iron |
| JP2005139528A (en) * | 2003-11-10 | 2005-06-02 | Nippon Steel Corp | Method for dephosphorization-refining molten pig iron |
| JP2008063645A (en) * | 2006-09-11 | 2008-03-21 | Jfe Steel Kk | Steelmaking method |
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| CN116640898A (en) * | 2023-05-10 | 2023-08-25 | 韶关星田金属制品有限公司 | Molten iron heat preservation method of smelting equipment |
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