JP2021152213A - Blast furnace operation method - Google Patents
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Abstract
Description
本発明は、特定のＭｇＯ源を副原料として使用する高炉の操業方法に関する。 The present invention relates to a method of operating a blast furnace using a specific MgO source as an auxiliary raw material.
高炉操業では、通常、還元材であるコークスと鉄源である鉱石原料を、炉内でコークスと鉱石原料が交互に層を形成するように、順次炉頂から炉内装入している。鉱石原料には造滓剤のような副原料を混合することもある。１層分のコークスや鉱石原料は、それぞれ所定量が１チャージ分の量として決められて炉内に装入されるが、このとき、炉内の半径方向でコークス層や鉱石原料層の厚さを調整することで、高炉内の半径方向でのガス流分布を制御している。また、このガス流分布の制御をより適正に行うために、１チャージ分のコークスや鉱石原料をそれぞれ分割し、複数のバッチとして装入することも行われている。 In blast furnace operation, normally, coke as a reducing material and ore raw material as an iron source are sequentially put into the furnace interior from the top of the furnace so that coke and ore raw material alternately form layers in the furnace. The ore raw material may be mixed with an auxiliary raw material such as a slag-making agent. Each of the coke and ore raw materials for one layer is charged into the furnace in a predetermined amount as the amount for one charge. At this time, the thickness of the coke layer and the ore raw material layer in the radial direction in the furnace. By adjusting, the gas flow distribution in the radial direction in the blast furnace is controlled. Further, in order to control the gas flow distribution more appropriately, one charge of coke and ore raw materials are each divided and charged as a plurality of batches.
高炉では、高温の空気または酸素富化空気を炉下部の羽口から炉内に吹き込むことで炉内のコークスを燃焼させ、この燃焼により発生する熱とＣＯガスを利用して鉱石原料の還元、溶融を行うことで溶銑が製造される。
鉱石原料は、採掘された鉄鉱石を破砕、篩い分けして得られる塊鉱石と、塊鉱石よりも小さい鉄鉱石を塊成化した焼結鉱やペレット等の処理鉱石とに、概ね大別される。塊鉱石と処理鉱石は、各高炉の操業条件に応じて選択的に使用されるが、一般的には、処理鉱石は原料鉱石の配合や副原料の調整が事前に行われ、品質が比較的一定に保たれるため、主要な鉱石原料として使用される。また、還元材については、炉頂から装入されるコークスの他に、石炭を粉砕した低コストの微粉炭を炉下部の羽口から吹き込み、燃焼させることも行われており、近年では、微粉炭使用量の拡大に伴い、コークス使用量が低減してきている。
In a blast furnace, hot air or oxygen-enriched air is blown into the furnace from the tuyere at the bottom of the furnace to burn the coke in the furnace, and the heat and CO gas generated by this combustion are used to reduce the ore raw material. Hot metal is produced by melting.
Raw materials for ore are roughly classified into lump ore obtained by crushing and sieving mined iron ore and processed ore such as sintered ore and pellets in which iron ore smaller than lump ore is lumped. NS. The lump ore and the treated ore are selectively used according to the operating conditions of each blast furnace, but in general, the treated ore is relatively high in quality because the raw material ore is mixed and the auxiliary raw materials are adjusted in advance. It is used as a major ore raw material because it is kept constant. As for the reducing agent, in addition to coke charged from the top of the furnace, low-cost pulverized coal made by crushing coal is also blown from the tuyere at the bottom of the furnace and burned. With the increase in the amount of charcoal used, the amount of coke used has been decreasing.
高炉で溶銑を製造する際に、鉱石原料に含有される脈石分や還元材に含まれる灰分が不純物として存在するが、これらは溶銑とともに出銑口から排滓する必要がある。そこで、副原料として造滓剤を添加し、適正な成分に調整した高炉スラグを生成させる。一般に、高炉スラグの主要構成成分は、ＳｉＯ２、ＣａＯ、ＭｇＯ及びＡｌ２Ｏ３の４成分である。このうちＳｉＯ２とＣａＯの含有率は、スラグ粘度による排滓性および溶銑中Ｓ濃度の低減の観点から、スラグ塩基度（ＣａＯ／ＳｉＯ２）が所定の値となるように調整される。これに対してＡｌ２Ｏ３は、主にコークス中の灰分や鉱石中に含まれるものであるため、その含有率は原燃料需給バランスにより変動し、調整が困難である。 When producing hot metal in a blast furnace, gangue contained in the ore raw material and ash contained in the reducing agent are present as impurities, but these must be discharged from the hot metal outlet together with the hot metal. Therefore, a slag-making agent is added as an auxiliary raw material to generate blast furnace slag adjusted to an appropriate component. In general, the main components of blast furnace slag are the four components of SiO 2 , CaO, MgO and Al 2 O 3. Of these, the contents of SiO 2 and CaO are adjusted so that the slag basicity (CaO / SiO 2 ) becomes a predetermined value from the viewpoint of the slag viscosity and the reduction of the S concentration in the hot metal. On the other hand, since Al 2 O 3 is mainly contained in ash and ore in coke, its content fluctuates depending on the balance between supply and demand of raw materials and fuel, and it is difficult to adjust.
一方、高炉スラグのＭｇＯ濃度は、適正に調整することにより高炉スラグの粘性を低減させて排滓性を向上させることが可能であり、また、高炉スラグをセメント原料として外販するために、Ｂ３＝（ＣａＯ＋ＭｇＯ＋Ａｌ２Ｏ３）／（ＳｉＯ２）という指標を基準値以上とする必要性から、ＭｇＯ源の添加が必要となる。一般にＭｇＯ源としては、ＭｇＯ−ＣａＯ系のドロマイトやＭｇＯ−ＳｉＯ２系の蛇紋岩を使用しているが、これらにはＣａＯやＳｉＯ２が含まれているため、所定のスラグ塩基度に調整するための副原料がさらに必要になり、スラグ比の増加を招き、コスト増となるだけでなく、スラグボリュームの増加による通気性の悪化を招くため、使用量が制限される。また、ＭｇＯ源としてマグネサイトを用いる場合もあるが、マグネサイトは塊状帯で粉化しやすいため、炉内通気性が悪化しやすい問題がある。 On the other hand, the MgO concentration of the blast furnace slag can be adjusted appropriately to reduce the viscosity of the blast furnace slag and improve the slag removal property, and in order to sell the blast furnace slag to the outside as a cement raw material, B3 = Since it is necessary to set the index (CaO + MgO + Al 2 O 3 ) / (SiO 2 ) to be equal to or higher than the reference value, it is necessary to add an MgO source. Generally, MgO-CaO-based dolomite and MgO-SiO 2 -based serpentine rock are used as the MgO source, but since these contain CaO and SiO 2 , they are adjusted to a predetermined slag basicity. This requires more auxiliary raw materials, which not only increases the slag ratio and costs, but also deteriorates the air permeability due to the increase in slag volume, so that the amount used is limited. Further, although magnesite may be used as the MgO source, there is a problem that the air permeability in the furnace tends to be deteriorated because the magnesite is easily pulverized in a massive band.
これに対して、特許文献１には、造滓剤として水酸化マグネシウム鉱石を炉頂部から炉内に装入することにより、スラグ比の上昇を抑制しつつスラグ中のＭｇＯ濃度を増加させる方法が開示されている。この方法によれば、ドロマイトやマグネサイトを使用した場合のような問題を生じることなく、高炉スラグのＭｇＯ濃度を増加させることができる。 On the other hand, Patent Document 1 describes a method in which magnesium hydroxide ore is charged into the furnace from the top of the furnace as a slag-forming agent to increase the MgO concentration in the slag while suppressing an increase in the slag ratio. It is disclosed. According to this method, the MgO concentration of the blast furnace slag can be increased without causing problems as in the case of using dolomite or magnesite.
しかし、一般にブルーサイトと呼ばれる水酸化マグネシウム鉱石は、原料単価が高く、これを高炉のＭｇＯ源として使用した場合、溶銑の製造コストが増加するという問題がある。
したがって本発明の目的は、以上のような従来技術の課題を解決し、高炉内の通気性を悪化させるなどの問題を生じることなく、低コストに高炉スラグのＭｇＯ濃度を増加させることができる高炉操業方法を提供することにある。
However, magnesium hydroxide ore, which is generally called brucite, has a high raw material unit price, and when it is used as an MgO source for a blast furnace, there is a problem that the production cost of hot metal increases.
Therefore, an object of the present invention is a blast furnace capable of solving the above-mentioned problems of the prior art and increasing the MgO concentration of the blast furnace slag at low cost without causing problems such as deterioration of air permeability in the blast furnace. It is to provide a method of operation.
本発明者は、上記のような課題を解決すべく検討を進めるなかで、安価なＭｇＯ源として、製鉄所内で発生するＭｇＯ−Ｃ系廃耐火物（使用済み耐火物）に着目した。製鉄所内では精錬工程で使用される反応容器や搬送容器にＭｇＯ−Ｃ系耐火物が用いられている。これは、ＭｇＯ−Ｃ系耐火物が溶鋼等の高温に耐えられ、且つ溶鋼や製鋼スラグと化学的に反応しにくい特性を有しているためである。ＭｇＯ−Ｃ系廃耐火物は、これら容器を補修した際に発生する廃材（解体屑）であり、高い含有率でＭｇＯを含有しているため、高炉のＭｇＯ源として利用することができる可能性がある。 The present inventor has focused on MgOC-based waste refractories (used refractories) generated in steelworks as an inexpensive MgO source while proceeding with studies to solve the above problems. In the steelworks, MgOC refractories are used for the reaction vessels and transport vessels used in the refining process. This is because the MgO-C refractory has the property of being able to withstand high temperatures such as molten steel and being less likely to chemically react with molten steel and steelmaking slag. The MgO-C type waste refractory is waste material (demolition waste) generated when these containers are repaired, and since it contains MgO at a high content rate, it may be used as an MgO source for a blast furnace. There is.
しかしながら、ＭｇＯ−Ｃ系耐火物の上記特性からして、さらには使用済みのＭｇＯ−Ｃ系耐火物は特に融点が高くなっていることからして、ＭｇＯ−Ｃ系廃耐火物をそのまま高炉の副原料として使用した場合、高炉内において上述した脈石や灰分とともに溶解して高炉スラグを生成するかどうかは未知数であり、また、使用済み耐火物を破砕・整粒した塊状のＭｇＯ−Ｃ系廃耐火物を高炉で使用した例がないことから、塊状のＭｇＯ−Ｃ系廃耐火物を使用した際の高炉内への影響についても明らかではなかった。そこで、本発明者らがさらに検討を進めた結果、塊状のＭｇＯ−Ｃ系廃耐火物を副原料（ＭｇＯ源）として使用しても、高炉内の通気性を悪化させるなどの問題を生じたり、高炉スラグの生成に支障を生じたりすることはなく、むしろ、次のような利点が得られることが判った。すなわち、塊状のＭｇＯ−Ｃ系廃耐火物を副原料として使用することにより、高炉内で最も通気性の悪い融着帯において、（i）ＭｇＯ−Ｃ系廃耐火物のＭｇＯが未還元状態のＦｅＯに固溶して高融点化合物を形成することにより、融着帯の通気性が改善される、（ii）さらに、ＭｇＯ−Ｃ系廃耐火物は融点が高いため融着帯の粒子間空隙率が高められ、これによっても融着帯の通気性が改善される、という効果が得られることが判った。 However, due to the above characteristics of the MgOC-based refractory and the fact that the used MgOC-based refractory has a particularly high melting point, the MgOC-based waste refractory can be used as it is in the blast furnace. When used as an auxiliary material, it is unknown whether or not it dissolves in the blast furnace together with the above-mentioned vein stones and ash to produce blast furnace slag, and it is a massive MgOC system obtained by crushing and sizing used refractories. Since there has been no example of using a waste refractory in a blast furnace, the effect on the inside of the blast furnace when using a massive MgOC-based waste refractory was not clear. Therefore, as a result of further studies by the present inventors, even if a massive MgO-C-based waste refractory is used as an auxiliary raw material (MgO source), problems such as deterioration of air permeability in the blast furnace may occur. It was found that the production of blast furnace slag was not hindered, but rather the following advantages were obtained. That is, by using the massive MgO-C-based waste refractory as an auxiliary raw material, (i) MgO of the MgO-C-based waste refractory is in an unreduced state in the cohesive zone having the worst air permeability in the blast furnace. By solidifying in FeO to form a blast furnace compound, the air permeability of the fusion zone is improved. (Ii) Furthermore, since the MgO-C-based waste refractory has a high melting point, the interparticle voids in the fusion zone It was found that the rate was increased, which also had the effect of improving the air permeability of the cohesive zone.
本発明は、このような知見に基づきなされたもので、以下を要旨とするものである。
［1］鉱石原料の少なくとも一部に副原料を混合して炉内に装入する高炉操業方法であって、鉱石原料に混合する副原料の少なくとも一部が、塊状のＭｇＯ−Ｃ系廃耐火物であることを特徴とする高炉操業方法。
［2］上記［1］の高炉操業方法において、塊状のＭｇＯ−Ｃ系廃耐火物が、使用済みのＭｇＯ−Ｃ系耐火物を破砕および整粒して得られたものであることを特徴とする高炉操業方法。
［3］上記［1］または［2］の高炉操業方法において、ＭｇＯ−Ｃ系廃耐火物の粒径が１０〜５０ｍｍであることを特徴とする高炉操業方法。
［4］上記［1］〜［3］のいずれかの高炉操業方法において、鉱石原料が処理鉱石と塊鉱石からなることを特徴とする高炉操業方法。
［5］上記［4］の高炉操業方法において、１チャージ分の鉱石原料を２バッチに分割して装入し、そのうち塊鉱石の質量比率の高い方のバッチにのみＭｇＯ−Ｃ系廃耐火物を混合することを特徴とする高炉操業方法。
［6］上記［4］の高炉操業方法において、１チャージ分の鉱石原料を２バッチに分割して装入し、各バッチにＭｇＯ−Ｃ系廃耐火物を混合するとともに、２バッチのうち塊鉱石の質量比率の高い方のバッチのＭｇＯ−Ｃ系廃耐火物の混合比率を、塊鉱石の質量比率の低い方のバッチのＭｇＯ−Ｃ系廃耐火物の混合比率と同じかそれよりも高くすることを特徴とする高炉操業方法。
The present invention has been made based on such findings, and the gist of the present invention is as follows.
[1] A blast furnace operation method in which at least a part of an ore raw material is mixed with an auxiliary material and charged into the furnace, and at least a part of the auxiliary material mixed with the ore raw material is a massive MgOC-based waste fire resistance. A blast furnace operation method characterized by being a thing.
[2] In the blast furnace operating method of the above [1], the massive MgOC-based waste refractory is obtained by crushing and sizing the used MgOC-based refractory. How to operate the blast furnace.
[3] The blast furnace operating method according to the above [1] or [2], wherein the particle size of the MgOC-based waste refractory is 10 to 50 mm.
[4] In the blast furnace operating method according to any one of the above [1] to [3], the blast furnace operating method is characterized in that the ore raw material is composed of treated ore and lump ore.
[5] In the blast furnace operation method of [4] above, one charge of ore raw material is divided into two batches and charged, and only the batch having the higher mass ratio of lump ore is the MgOC-based waste refractory. A blast furnace operating method characterized by mixing.
[6] In the blast furnace operation method of the above [4], one charge of ore raw material is divided into two batches and charged, and MgOC-based waste refractory is mixed in each batch, and a lump of the two batches is mixed. The mixing ratio of MgOC-based waste refractory in the batch with the higher mass ratio of ore is equal to or higher than the mixing ratio of MgOC-based waste refractory in the batch with the lower mass ratio of lump ore. A method of operating a blast furnace, which is characterized by doing so.
本発明によれば、副原料（ＭｇＯ源）として安価なＭｇＯ−Ｃ系廃耐火物を使用することにより、溶銑製造コストを抑制しつつ、高炉内の通気性を悪化させたり、高炉スラグの生成に支障を生じさせたりすることなく、高炉スラグのＭｇＯ濃度を増加させることができる。さらに、副原料として塊状のＭｇＯ−Ｃ系廃耐火物を使用することにより、ＭｇＯ−Ｃ系廃耐火物のＭｇＯが未還元状態のＦｅＯに固溶して高融点化合物を形成すること、さらには、ＭｇＯ−Ｃ系廃耐火物は融点が高いため融着帯の粒子間空隙率が高められることによって、高炉内で最も通気性の悪い融着帯の通気性を改善することができる。このように通気性が改善されることにより、還元材としてコークスよりも安価な微粉炭の使用量を増加させることができるので、同じ出銑比、還元材比の操業であっても、コークス比を低減することができ、溶銑製造コストをより低減することができる。 According to the present invention, by using an inexpensive MgO-C-based waste refractory as an auxiliary raw material (MgO source), the air permeability in the blast furnace is deteriorated and the blast furnace slag is generated while suppressing the hot metal production cost. The MgO concentration of the blast furnace slag can be increased without causing any trouble. Further, by using a massive MgO-C-based waste refractory as an auxiliary raw material, MgO of the MgO-C-based waste refractory is dissolved in FeO in an unreduced state to form a blast furnace compound, and further. Since the MgOC-based waste refractory has a high melting point, the interparticle void ratio of the cohesive zone is increased, so that the air permeability of the cohesive zone having the worst air permeability in the blast furnace can be improved. By improving the air permeability in this way, it is possible to increase the amount of pulverized coal used as a reducing agent, which is cheaper than coke. Therefore, even if the operation has the same tapping ratio and reducing agent ratio, the coke ratio Can be reduced, and the hot metal production cost can be further reduced.
本発明者らは、高炉内に副原料として装入されるＭｇＯ源が、高炉内に及ぼす影響について評価するために、ＭｇＯ源として、ＭｇＯ−Ｃ系廃耐火物（以下、説明の便宜上「ＭｇＯ−Ｃ耐火物屑」という場合がある。）、マグネサイト、ブルーサイト、ドロマイトを用いてラボ試験を行い、それぞれの試験結果を比較した。試験に使用したＭｇＯ−Ｃ耐火物屑、マグネサイト、ブルーサイト、ドロマイトの化学成分を表１に示す。ＭｇＯ−Ｃ耐火物屑は精錬容器などで使用されたものであるため、その化学成分には、付着したスラグ成分（ＣａＯ，Ａｌ２Ｏ３など）も含まれている。
なお、以下の説明における材料の粒径は、当該数値の目開きの篩で篩った際の篩上または篩下となる材料の粒径を意味する。
In order to evaluate the effect of the MgO source charged into the blast furnace as an auxiliary material on the inside of the blast furnace, the present inventors use an MgO-C-based waste refractory as the MgO source (hereinafter, for convenience of explanation, "MgO". -C Refractory waste "), magnesite, brucite, and dolomite were used in laboratory tests, and the test results were compared. Table 1 shows the chemical components of MgOC refractory waste, magnesite, brucite, and dolomite used in the test. Since MgO-C refractory waste is used in a refining container or the like, its chemical composition also includes an attached slag component (CaO, Al 2 O 3, etc.).
In addition, the particle size of the material in the following description means the particle size of the material which becomes above or below the sieve when sieving with the sieve of the corresponding numerical value.
最初に、高炉の塊状帯におけるＭｇＯ源の粉化し易さを評価するため、粒径を１５〜２０ｍｍに整粒した５００ｇの試料を目皿の上に乗せ、内径７０ｍｍの反応管の中に静置させた。その後、１５ＮＬ／ｍｉｎのＮ２ガスにて反応管内部を置換した後、１５ＮＬ／ｍｉｎのＮ２ガスを導入させたまま６０分間で反応管内部を７００℃まで昇温させた。その後、７００℃にて３０分間１５ＮＬ／ｍｉｎのＮ２ガスを導入した後に、１５ＮＬ／ｍｉｎのＣＯ：ＣＯ２＝３０：７０の混合ガスに切り替えて３０分間導入し、試料を還元ガスにて反応させた。その後、再び１５ＮＬ／ｍｉｎのＮ２ガスに切り替えて導入し、常温まで試料を冷却した。冷却後の試料質量を測定した後、試料全量をＪＩＳＭ８７２０に記載の回転試験機の中に装入し、３０ｒｐｍで３０分間、計９００回転させた後、目開きが１５ｍｍおよび２．８ｍｍの篩を用いて分級した。回転試験機への装入質量に対する粒径２．８ｍｍ以下の質量比率を算出し、各原料間で比較をした。その結果を図１に示す。 First, in order to evaluate the ease of pulverization of the MgO source in the massive zone of the blast furnace, a 500 g sample having a particle size of 15 to 20 mm was placed on a perforated plate and statically placed in a reaction tube having an inner diameter of 70 mm. I let you put it. Then, after replacing the inner reaction tube at N 2 gas 15 NL / min, the inner reaction tube was raised to 700 ° C. for 60 minutes while keeping introducing N 2 gas 15 NL / min. Then, after introducing 15 NL / min N 2 gas at 700 ° C. for 30 minutes, the mixture was switched to a mixed gas of 15 NL / min CO: CO 2 = 30: 70 and introduced for 30 minutes, and the sample was reacted with the reducing gas. I let you. Then, the sample was introduced again by switching to 15 NL / min N 2 gas, and the sample was cooled to room temperature. After measuring the mass of the sample after cooling, the entire amount of the sample was placed in the rotation tester described in JIS M8720, and the sample was rotated at 30 rpm for 30 minutes for a total of 900 rotations. Classified using. The mass ratio of the particle size of 2.8 mm or less to the mass charged into the rotary tester was calculated, and comparisons were made between the raw materials. The result is shown in FIG.
図１によれば、マグネサイトの粒径２．８ｍｍ以下の質量比率は６０mass％近くになっており、他のＭｇＯ−Ｃ耐火物屑、ブルーサイト、ドロマイトの粒径２．８ｍｍ以下の質量比率がいずれも２０mass％以下となっていることと比較すると、粉化が著しいと言える。これは、マグネサイトが熱分解によりＣＯ２を放出し、割れが発生したためであると考えられる。ドロマイトも熱分解によりＣＯ２を放出し、割れを発生させると考えられるが、熱分解温度がマグネサイトの方が低温であったため、今回の試験ではマグネサイトのみ粉化が著しかったものと考えられる。以上の結果から、マグネサイトのＭｇＯ源としての使用は、高炉の塊状帯での粉化により通気性を悪化させるので好ましくないと言える。これに対してＭｇＯ−Ｃ耐火物屑は、元々強度が高く、熱分解により割れが発生することもないので、粉化しにくく、高炉の塊状帯での粉化により通気性を悪化させることもない。 According to FIG. 1, the mass ratio of magnesite having a particle size of 2.8 mm or less is close to 60 mass%, and the mass ratio of other MgOC refractory waste, brucite, and dolomite having a particle size of 2.8 mm or less. Compared with the fact that all of them are 20 mass% or less, it can be said that the pulverization is remarkable. It is considered that this is because magnesite released CO 2 by thermal decomposition and cracked. It is thought that dolomite also releases CO 2 by thermal decomposition and causes cracking, but since the thermal decomposition temperature was lower in magnesite, it is probable that only magnesite was significantly pulverized in this test. .. From the above results, it can be said that the use of magnesite as an MgO source is not preferable because it deteriorates the air permeability due to pulverization in the blast furnace mass zone. On the other hand, MgO-C refractory waste has high strength from the beginning and does not crack due to thermal decomposition, so that it is difficult to pulverize, and pulverization in the blast furnace mass zone does not deteriorate the air permeability. ..
次に、高炉の融着帯におけるＭｇＯ源の通気性への影響について評価するため、高温荷重軟化試験を行った。使用した高温荷重軟化実験装置の概略を図３に示すが、この装置は、試料を黒鉛坩堝に装入し、坩堝上部より荷重を印加させつつ、坩堝下部より気体を導入する構造となっている。黒鉛坩堝の内径は１００ｍｍであり、試料の上下を粒径１５ｍｍのジルコニアボールの充填層で被覆して試験を行った。試料の上下の充填層は、コークス粒子を使用するのが一般的であるが、実験後に試料の坩堝内残留物の質量を測定するため、化学的に安定なジルコニアボールを用いて炉内残留物との差別化を図った。試料は、粒径を１０−１５ｍｍに整粒した焼結鉱と、ＭｇＯ源とを均一に混合したものを用い、試料全体の質量が９００ｇとなるようにし、ＭｇＯ源の混合質量を適宜変化させて実験を行った。ＭｇＯ源としては、塊状帯での粉化が低位であった、ＭｇＯ−Ｃ耐火物屑、ブルーサイト、ドロマイトを用いた。 Next, a high-temperature load softening test was conducted to evaluate the effect of the MgO source on the air permeability in the fusion zone of the blast furnace. The outline of the high-temperature load softening experimental device used is shown in FIG. 3. This device has a structure in which a sample is charged into a graphite crucible, a load is applied from the upper part of the crucible, and gas is introduced from the lower part of the crucible. .. The inner diameter of the graphite crucible was 100 mm, and the test was conducted by coating the top and bottom of the sample with a packed layer of zirconia balls having a particle size of 15 mm. Coke particles are generally used for the upper and lower packing layers of the sample, but in order to measure the mass of the residue in the pit of the sample after the experiment, chemically stable zirconia balls are used for the residue in the furnace. I tried to differentiate from. The sample used was a uniform mixture of sinter having a particle size of 10 to 15 mm and an MgO source, so that the total mass of the sample was 900 g, and the mixed mass of the MgO source was appropriately changed. The experiment was conducted. As the MgO source, MgO-C refractory waste, brucite, and dolomite, which had a low level of pulverization in the massive band, were used.
上述のように黒鉛坩堝に装入した実験試料に対して、高炉雰囲気を模した温度、ガス組成、荷重を付与して、坩堝内圧損と試料層厚の変位を調査した。炉内温度は、室温から９００℃までを５℃／ｍｉｎ、９００℃から１１００℃までを２℃／ｍｉｎ、１１００℃から１６５０℃までを５℃／ｍｉｎの昇温速度となるよう調整した。ガス組成は室温から炉内温度が３００℃まではＮ２ガスのみ導入し、３００℃以上の温度では、表２のように炉内温度によって組成を変化させ、合計のガス流量が３０ＮＬ／ｍｉｎとなるように調整した。荷重は、炉内温度が１０００℃となるまでは、１０００℃において８０ｋｇｆ／ｃｍ２となるよう、炉内温度に対して直線的に荷重を与え、１０００℃以降は８０ｋｇｆ／ｃｍ２一定となるよう調整した。 As described above, the experimental sample charged into the graphite crucible was given a temperature, gas composition, and load imitating the atmosphere of a blast furnace, and the pressure loss inside the crucible and the displacement of the sample layer thickness were investigated. The temperature inside the furnace was adjusted so that the temperature rise rate was 5 ° C./min from room temperature to 900 ° C., 2 ° C./min from 900 ° C. to 1100 ° C., and 5 ° C./min from 1100 ° C. to 1650 ° C. As for the gas composition, only N 2 gas is introduced from room temperature to the temperature inside the furnace at 300 ° C, and at temperatures above 300 ° C, the composition is changed according to the temperature inside the furnace as shown in Table 2, and the total gas flow rate is 30 NL / min. Adjusted to be. The load is linearly applied to the furnace temperature so that it is 80 kgf / cm 2 at 1000 ° C until the furnace temperature reaches 1000 ° C, and becomes constant at 80 kgf / cm 2 after 1000 ° C. It was adjusted.
試験結果の一例として、ＭｇＯ源の混合量を２４ｇとした場合の、炉内温度に対する坩堝内圧損の推移を図２に示す。この時のＭｇＯ源の混合量は実機での混合量４４ｋｇ／ｔ（ｔ：溶銑ton。以下同様）に相当する。図２によれば、ＭｇＯ源としてドロマイトを使用した場合と比較して、ＭｇＯ−Ｃ耐火物屑、ブルーサイトを使用した場合は、圧損がピークとなる温度が高温となり、かつ最大圧損も低位となった。これは、ＭｇＯ−Ｃ耐火物屑に含有されるＭｇＯや、ブルーサイト中の水酸化マグネシウムが熱分解して生じたＭｇＯが、未還元状態のＦｅＯに固溶して高融点化合物を形成したためであると考えられる。また、ＭｇＯ−Ｃ耐火物屑の方が、ブルーサイトよりも最大圧損が低位となったのは、融着状態においてもＭｇＯ粒子が残存し、高い粒子間空隙率が維持されたためと考えられる。実験後の黒鉛坩堝内のジルコニアボール以外の残存物を回収したが、いずれのサンプルにおいても未溶解のＭｇＯ源は回収されなかった。このことから、融着状態において残存していたＭｇＯ−Ｃ耐火物屑は、さらなる高温となる溶け落ちの段階ではスラグ中に溶解し、未溶解物としては炉内に残留しなかったものと考えられる。使用済みのＭｇＯ−Ｃ耐火物は特に融点が高く、これを塊状で使用することによる溶け残りが懸念されたが、このように溶け残りのおそれはないと考えられる。これらの結果から、融着帯での通気性改善効果は、ＭｇＯ−Ｃ耐火物屑が最も高いことが判った。 As an example of the test results, FIG. 2 shows the transition of the pressure loss in the crucible with respect to the temperature inside the furnace when the mixing amount of the MgO source is 24 g. The mixing amount of the MgO source at this time corresponds to the mixing amount of 44 kg / t (t: hot metal ton, the same applies hereinafter) in the actual machine. According to FIG. 2, compared with the case where dromite is used as the MgO source, when MgO-C refractory waste and brucite are used, the temperature at which the pressure loss peaks is higher and the maximum pressure loss is also lower. became. This is because MgO contained in MgO-C refractory waste and MgO generated by thermal decomposition of magnesium hydroxide in brucite are dissolved in unreduced FeO to form a refractory compound. It is believed that there is. Further, it is considered that the reason why the maximum pressure drop of MgO-C refractory waste was lower than that of brucite was that MgO particles remained even in the fused state and a high interparticle porosity was maintained. Residues other than zirconia balls in the graphite crucible after the experiment were recovered, but the undissolved MgO source was not recovered in any of the samples. From this, it is considered that the MgOC refractory debris remaining in the fused state was dissolved in the slag at the stage of melting down at a higher temperature, and did not remain in the furnace as an undissolved material. Be done. The used MgO-C refractory has a particularly high melting point, and there is a concern that it may remain undissolved due to its use in the form of a lump. However, it is considered that there is no possibility of the undissolved residue. From these results, it was found that MgOC refractory waste has the highest effect of improving air permeability in the cohesive zone.
融着帯においてＭｇＯ−Ｃ耐火物屑が反応・溶解し切らずに、未溶解物が炉下部に残存すると、ＦｅＯ濃度の低い高炉スラグへのＭｇＯの溶解速度は低く、炉下部にＭｇＯの未溶解物が滞留してしまうため、通気性の悪化を引き起こす。このためＭｇＯ−Ｃ耐火物屑は、高炉において必要とされるＭｇＯ濃度に応じて、適量を混合することが好ましい。ＭｇＯ−Ｃ耐火物屑の未溶解が発生する可能性について、実機で使用するＭｇＯ−Ｃ耐火物屑の代表粒径である２０−２５ｍｍに整粒した試料を用いて調査した。その結果、ＭｇＯ−Ｃ耐火物屑の混合量を、粒径が１０−１５ｍｍの時と同様に２４ｇ（実機での混合量４４ｋｇ／ｔに相当）にして試験を行ったところ、最大圧損は０．４２ｋＰａとなり、粒径が１０−１５ｍｍの時よりも若干の低減が認められたが、試験後の黒鉛坩堝内への未溶解物の残存は認められなかった。ここで、ＭｇＯ−Ｃ耐火物屑の混合量として４４ｋｇ／ｔは、通常、高炉で必要とされるＭｇＯ濃度に対して十分に大きい混合量であり、したがって、ＭｇＯ源としてＭｇＯ−Ｃ耐火物屑を用いても、溶解性の面での問題はないことが判った。 If the MgO-C refractory waste does not completely react and dissolve in the fusion zone and the undissolved material remains in the lower part of the furnace, the dissolution rate of MgO in the blast furnace slag with a low FeO concentration is low, and the MgO is not yet dissolved in the lower part of the furnace. Since the dissolved substance stays, it causes deterioration of air permeability. Therefore, it is preferable to mix an appropriate amount of MgO-C refractory waste according to the MgO concentration required in the blast furnace. The possibility of undissolved MgO-C refractory waste was investigated using a sample sized to 20-25 mm, which is a typical particle size of MgO-C refractory waste used in an actual machine. As a result, when the mixed amount of MgO-C refractory crucible was set to 24 g (corresponding to the mixed amount of 44 kg / t in the actual machine) as in the case of the particle size of 10-15 mm, the maximum pressure loss was 0. The particle size was .42 kPa, which was slightly lower than that when the particle size was 10-15 mm, but no undissolved material remained in the graphite crucible after the test. Here, 44 kg / t as the mixing amount of MgO-C refractory waste is a mixing amount sufficiently larger than the MgO concentration normally required in a blast furnace, and therefore, MgO-C refractory waste as an MgO source. It was found that there was no problem in terms of solubility even when using.
そこで、本発明では、鉱石原料の少なくとも一部に副原料を混合して炉内に装入する高炉操業方法において、鉱石原料に混合する副原料（ＭｇＯ源）の少なくとも一部として、塊状のＭｇＯ−Ｃ耐火物屑（ＭｇＯ−Ｃ系廃耐火物）を用いる。
ここで、ＭｇＯ−Ｃ系耐火物（所謂「ＭｇＯ−Ｃ耐火物」）とは、ＭｇＯ（マグネシア原料）とＣ（カーボン原料）を主成分とし、必要に応じて金属添加物などの添加物を少量含有するものであり、一般的な組成としては、ＭｇＯ（マグネシア原料）と８〜２５mass％程度のＣ（カーボン原料）からなる耐火性原料に対して、外割で１．５mass％以下（無添加の場合を含む）の添加物を含有するものである。
ＭｇＯ−Ｃ系耐火物（定形耐火物、不定形耐火物）は、製鉄所内の精錬工程などで使用される反応容器や搬送容器の内張りなどに使用されており、これら反応容器や搬送容器の補修（内張りの張り替えなど）時に使用済み耐火物が発生する。本発明で使用するＭｇＯ−Ｃ耐火物屑は、主としてそのような使用済み耐火物を破砕および整粒（通常、篩い分けによる整粒）して得られた塊状の耐火物屑である。
Therefore, in the present invention, in the blast furnace operating method in which an auxiliary raw material is mixed with at least a part of the ore raw material and charged into the furnace, massive MgO is used as at least a part of the auxiliary raw material (MgO source) to be mixed with the ore raw material. -C Refractory waste (MgOC-based waste refractory) is used.
Here, the MgO-C refractory (so-called "MgO-C refractory") is mainly composed of MgO (magnesia raw material) and C (carbon raw material), and if necessary, additives such as metal additives are added. It is contained in a small amount, and as a general composition, it is 1.5 mass% or less (none) with respect to a refractory raw material composed of MgO (magnesia raw material) and C (carbon raw material) of about 8 to 25 mass%. It contains additives (including the case of addition).
MgOC-based refractories (standard refractories, non-standard refractories) are used for the lining of reaction vessels and transport vessels used in the refractory process in steelworks, and repair of these reaction vessels and transport vessels. Used refractory is generated at the time (replacement of lining, etc.). The MgO-C refractory waste used in the present invention is a lumpy refractory waste obtained mainly by crushing and sizing (usually sizing by sieving) such a used refractory material.
塊状のＭｇＯ−Ｃ耐火物屑は、高炉に装入する鉱石原料の全てに混合してもよいし、後述する形態のように鉱石原料の一部（例えば、１チャージ分の鉱石原料を複数バッチで装入する場合、一部のバッチの鉱石原料）にのみ混合してもよい。鉱石原料にＭｇＯ−Ｃ耐火物屑を混合するには、例えば、装入コンベアで搬送中の鉱石原料上にＭｇＯ−Ｃ耐火物屑を切り出せばよい。
なお、ＭｇＯ−Ｃ耐火物屑が混合される鉱石原料には、他の副原料を混合してもよい。
The massive MgO-C refractory waste may be mixed with all of the ore raw materials charged into the blast furnace, or a part of the ore raw materials (for example, a plurality of batches of ore raw materials for one charge) as described later. When charging with, it may be mixed only with some batches of ore raw material). In order to mix MgO-C refractory waste with the ore raw material, for example, MgO-C refractory waste may be cut out on the ore raw material being conveyed by the charging conveyor.
In addition, other auxiliary raw materials may be mixed with the ore raw material to which MgOC refractory waste is mixed.
塊状のＭｇＯ−Ｃ耐火物屑は、粒径が大き過ぎると融着帯で反応・溶解し切らずに、未溶解物が炉下部に残存してしまう恐れがあり、一方、粒径が小さ過ぎると炉内の通気性を阻害するおそれがあるため、粒径は１０〜５０ｍｍ程度が好ましく、１０〜４０ｍｍがより好ましい。ここで、粒径１０〜５０ｍｍとは、目開き１０ｍｍの篩を通過せず、且つ目開き５０ｍｍの篩を通過する粒径であり、また、粒径１０〜４０ｍｍとは、目開き１０ｍｍの篩を通過せず、且つ目開き４０ｍｍの篩を通過する粒径である。
鉱石原料としては、採掘された鉄鉱石を破砕・分級して得られる塊鉱石と、塊鉱石よりも小さい鉄鉱石を塊成化した焼結鉱やペレット等の処理鉱石が挙げられる。塊鉱石と処理鉱石とは、高炉の操業条件に応じて選択的に使用されるが、一般には処理鉱石を主体として塊鉱石＋処理鉱石が用いられるか、処理鉱石のみが用いられる。
If the particle size of the massive MgO-C refractory waste is too large, it may not react and dissolve completely in the cohesive zone, and undissolved material may remain in the lower part of the furnace, while the particle size is too small. The particle size is preferably about 10 to 50 mm, more preferably 10 to 40 mm, because it may hinder the air permeability in the furnace. Here, the particle size of 10 to 50 mm is a particle size that does not pass through a sieve having a mesh size of 10 mm and passes through a sieve having a mesh size of 50 mm, and the particle size of 10 to 40 mm is a sieve having a mesh size of 10 mm. It is a particle size that does not pass through the sieve and passes through a sieve having a mesh size of 40 mm.
Examples of the ore raw material include lump ore obtained by crushing and classifying mined iron ore, and processed ore such as sintered ore and pellets obtained by lumping iron ore smaller than the lump ore. The lump ore and the treated ore are selectively used according to the operating conditions of the blast furnace, but generally, the lump ore + the treated ore is mainly used as the treated ore, or only the treated ore is used.
また、ＭｇＯ−Ｃ耐火物屑は鉱石原料中の脈石成分の中ではＦｅＯと最も反応するため、ＭｇＯ−Ｃ耐火物屑を融着帯で適切に反応・溶解させ、炉下部で未溶解の残留物が生じないようにするという観点からは、融着帯において鉱石原料中にＦｅＯが残存している方が望ましい。ここで、処理鉱石と塊鉱石とでは、塊鉱石の方が被還元性が低く、融着帯においてＦｅＯが還元されずに残存しやすいため、ＭｇＯ−Ｃ耐火物屑を塊鉱石の周りに置いた方が溶解しやすく、有利であると言える。そこで、鉱石原料が処理鉱石と塊鉱石からなる場合に、１チャージ分の鉱石原料を２バッチに分割して装入し、そのうち塊鉱石の質量比率の高いバッチの方にのみＭｇＯ−Ｃ耐火物屑を混合することが好ましい。これによりＭｇＯ−Ｃ耐火物屑の融着帯における溶解を促進させ、炉下部で未溶解の残留物が生じにくくすることができる。また、同様の趣旨で、１チャージ分の鉱石原料を２バッチに分割して装入し、各バッチにＭｇＯ−Ｃ耐火物屑を混合するとともに、２バッチのうち塊鉱石の質量比率の高い方のバッチのＭｇＯ−Ｃ耐火物屑の混合比率（鉱石原料とＭｇＯ−Ｃ耐火物屑の合計量に対するＭｇＯ−Ｃ耐火物屑量の割合。以下同様）を、塊鉱石の質量比率の低い方のバッチのＭｇＯ−Ｃ耐火物屑の混合比率と同じかそれよりも高くするようにしてもよい。このようにした場合でも、上記のように塊鉱石の質量比率の高いバッチの方にのみＭｇＯ−Ｃ耐火物屑を混合する場合よりも効果は若干低くなることはあるものの、ＭｇＯ−Ｃ耐火物屑の融着帯における溶解を促進させ、炉下部で未溶解の残留物が生じにくくすることができる。 In addition, since MgO-C refractory waste reacts most with FeO among the gangue components in the ore raw material, MgO-C refractory waste is appropriately reacted and dissolved in the cohesive zone and undissolved in the lower part of the furnace. From the viewpoint of preventing the formation of residues, it is desirable that FeO remains in the ore raw material in the cohesive zone. Here, among the treated ore and the lump ore, the lump ore has a lower reducibility, and FeO is likely to remain without being reduced in the cohesive zone. Therefore, MgO-C refractory waste is placed around the lump ore. It can be said that it is easier to dissolve and is advantageous. Therefore, when the ore raw material consists of treated ore and lump ore, one charge of ore raw material is divided into two batches and charged, and only the batch with a high mass ratio of lump ore is the MgOC refractory. It is preferable to mix the scraps. As a result, dissolution of MgOC refractory waste in the fusion zone can be promoted, and undissolved residue can be less likely to be generated in the lower part of the furnace. For the same purpose, one charge of ore raw material is divided into two batches and charged, and MgOC refractory waste is mixed in each batch, and the one with the higher mass ratio of lump ore in the two batches. The mixing ratio of MgO-C refractory waste in the batch (the ratio of the amount of MgO-C refractory waste to the total amount of ore raw material and MgO-C refractory waste. The mixing ratio of the batch MgOC refractory debris may be equal to or higher than that. Even in this case, although the effect may be slightly lower than that of mixing MgO-C refractory waste only in the batch having a high mass ratio of lump ore as described above, MgOC refractory It is possible to promote the dissolution of the waste in the cohesive zone and prevent the formation of undissolved residue in the lower part of the furnace.
なお、ＭｇＯ−Ｃ耐火物屑の混合量の実質的な上限を確認するため、さらに、ＭｇＯ−Ｃ耐火物屑の混合量を、実機での混合量５４ｋｇ／ｔに相当する３０ｇに増加させて試験を行ったところ、最大圧損は０．３７ｋＰａとなり、さらに圧損が低減したが、試験後の黒鉛坩堝内に未溶解物と思われる試料が視認され、化学分析の結果、ＭｇＯ−Ｃ耐火物屑であることが確認された。この結果からして、実機におけるＭｇＯ−Ｃ耐火物屑の混合量は５０ｋｇ／ｔ程度を上限とするのが好ましい。 In order to confirm the practical upper limit of the mixing amount of MgO-C refractory scraps, the mixing amount of MgO-C refractory scraps is further increased to 30 g, which corresponds to the mixing amount of 54 kg / t in the actual machine. When the test was conducted, the maximum pressure loss was 0.37 kPa, and the pressure loss was further reduced. It was confirmed that. From this result, it is preferable that the mixing amount of MgOC refractory waste in the actual machine is up to about 50 kg / t.
実機のベルレス高炉（内容積：５１５３ｍ３、炉口径：１１．４ｍ）用いて、以下のような試験操業を行った。１チャージ分の原料は、コークスを１バッチで、塊鉱石および焼結鉱からなる鉱石原料を２バッチでそれぞれ装入した。鉱石原料の装入では、高炉ガスの中心流と周辺流の比率を適正に保ち、炉内の通気性を確保するために、第１バッチでは鉱石原料に対する焼結鉱の割合（処理鉱比）が６７mass％の鉱石原料a-1を、第２バッチでは鉱石原料に対する焼結鉱の割合（処理鉱比）が７３mass％の鉱石原料a-2を、それぞれ装入した。ここで、鉱石原料を構成する塊鉱石はＴ．Ｆｅが６３mass％、同じく焼結鉱はＴ．Ｆｅが５７mass％であった。 The following test operation was carried out using the actual Bellless blast furnace (internal volume: 5153 m 3, furnace diameter: 11.4 m). As the raw material for one charge, coke was charged in one batch, and the ore raw material composed of lump ore and sinter was charged in two batches. When charging the ore raw material, in order to maintain an appropriate ratio between the central flow and the peripheral flow of the blast furnace gas and ensure the air permeability in the furnace, the ratio of sintered ore to the ore raw material (treated ore ratio) in the first batch. 67 mass% of ore raw material a-1 was charged, and in the second batch, the ore raw material a-2 having a ratio of sintered ore to the ore raw material (treated ore ratio) of 73 mass% was charged. Here, the lump ore constituting the ore raw material is T.I. Fe is 63 mass%, and the sinter is T.I. Fe was 57 mass%.
使用したコークスの平均粒径（分級した目開きをもとに算出される調和平均径）は４０ｍｍであり、鉱石原料a-1および鉱石原料a-2のそれぞれの平均粒径（分級した目開きをもとに算出される調和平均径）は１２ｍｍであった。ここで、調和平均径は、適正にサンプリングしたサンプルを、コークスは表５、鉱石は表６に示す目開きの篩で篩い分け、それぞれの表に示した代表径を使用して計算した。
鉱石原料a-1および鉱石原料a-2のそれぞれの装入量は、出銑比とコークス比とから決定され、１バッチ当たり９０〜１００ｔの範囲となった。
ＭｇＯ源としては、ＭｇＯ−Ｃ耐火物屑、ブルーサイト、ドロマイト、マグネサイトを用いた。これらＭｇＯ源は、目開き５０ｍｍの篩で篩った篩下材を、さらに目開き１０ｍｍの篩で篩った篩上材を用い、これを鉱石原料a-1または／および鉱石原料a-2に混合量を変えて混合した。本実施例の操業結果を表３および表４に示す。
なお、ＭｇＯ源を鉱石原料a-1、a-2の両方に混合した実施例のうち、発明例３、６と比較例７〜１２については、鉱石原料a-1、a-2それぞれの鉱石原料量に対して同じ混合比率になるようにＭｇＯ源を混合し、一方、発明例８〜１１については、鉱石原料a-1の鉱石原料量に対する混合比率が鉱石原料a-2の鉱石原料量に対する混合比率よりも高くなるようにＭｇＯ源を混合した。
The average particle size of the coke used (harmonic mean diameter calculated based on the classified opening) is 40 mm, and the average particle size of each of the ore raw material a-1 and the ore raw material a-2 (classified opening). The harmonic mean diameter calculated based on the above was 12 mm. Here, the harmonic mean diameter was calculated by sieving an appropriately sampled sample with a sieve having a mesh shown in Table 5 for coke and Table 6 for ore, and using the representative diameter shown in each table.
The charge amounts of the ore raw material a-1 and the ore raw material a-2 were determined from the tapping ratio and the coke ratio, and were in the range of 90 to 100 tons per batch.
As the MgO source, MgO-C refractory waste, brucite, dolomite, and magnesite were used. For these MgO sources, a sieving material sieved with a sieve having a mesh size of 50 mm and a sieving material sieved with a sieve having a mesh size of 10 mm are used, which are used as an ore raw material a-1 or / and an ore raw material a-2. The mixture was mixed by changing the mixing amount. The operation results of this embodiment are shown in Tables 3 and 4.
Of the examples in which the MgO source was mixed with both the ore raw materials a-1 and a-2, in Invention Examples 3 and 6 and Comparative Examples 7 to 12, the ores of the ore raw materials a-1 and a-2, respectively. The MgO source is mixed so that the mixing ratio is the same as the amount of the raw material, while in Invention Examples 8 to 11, the mixing ratio of the ore raw material a-1 to the amount of the ore raw material is the amount of the ore raw material a-2. The MgO source was mixed so as to be higher than the mixing ratio with respect to.
発明例１〜１１では、ＭｇＯ−Ｃ耐火物屑の混合量を５０ｋｇ／ｔ以下として、鉱石原料中に混合した。これらの発明例では、高炉内の融着帯において、ＭｇＯが未還元状態のＦｅＯに固溶して高融点化合物を形成したことに加えて、融点の高いＭｇＯ源が存在することで粒子間空隙率が高められ、炉内通気性が改善されたものと考えられる。その結果、出銑比を低下させることなく微粉炭比を増加させることができ、コークス比を３５０ｋｇ／ｔ以下とすることができた。
発明例１〜３、８、９では、ＭｇＯ−Ｃ耐火物屑の混合量を１０ｋｇ／ｔとし、それぞれ鉱石原料a-1、鉱石原料a-2、鉱石原料a-1およびa-2に混合した。これらの発明例では、ＭｇＯ−Ｃ耐火物屑の混合量が比較的少ないために、融着帯でのＭｇＯ−Ｃ耐火物屑の融解挙動に差異はなく、いずれの条件においてもコークス比は３５０ｋｇ／ｔとなった。
In Invention Examples 1 to 11, the amount of MgOC refractory waste mixed was 50 kg / t or less, and the mixture was mixed in the ore raw material. In these examples of the invention, in the fusion zone in the blast furnace, in addition to the solid dissolution of MgO in the unreduced FeO to form a high melting point compound, the presence of a high melting point MgO source causes interparticle voids. It is probable that the rate was increased and the air permeability in the furnace was improved. As a result, the pulverized coal ratio could be increased without lowering the tapping ratio, and the coke ratio could be 350 kg / t or less.
In Invention Examples 1 to 3, 8 and 9, the mixing amount of MgOC refractory waste is 10 kg / t, and the mixture is mixed with the ore raw material a-1, the ore raw material a-2, and the ore raw materials a-1 and a-2, respectively. bottom. In these invention examples, since the mixing amount of MgO-C refractory waste is relatively small, there is no difference in the melting behavior of MgO-C refractory waste in the cohesive zone, and the coke ratio is 350 kg under all conditions. It became / t.
一方、発明例４〜６、１０、１１では、ＭｇＯ−Ｃ耐火物屑の混合量を２５ｋｇ／ｔとし、それぞれ鉱石原料a-1、鉱石原料a-2、鉱石原料a-1およびa-2に混合した。これらの発明例のうち、ＭｇＯ−Ｃ耐火物屑を鉱石原料a-1にのみ混合した発明例４のコークス比が３４７ｋｇ／ｔと最も低位となり、ＭｇＯ−Ｃ耐火物屑を鉱石原料a-1およびa-2に対して混合比率が鉱石原料a-1≧鉱石原料a-2となるように混合した発明例６、１０、１１のコークス比が３４８ｋｇ／ｔと次に低く、ＭｇＯ−Ｃ耐火物屑を鉱石原料a-2にのみ混合した発明例５のコークス比が３４９ｋｇ／ｔと最も高くなった。これは、発明例４では、ＭｇＯ−Ｃ耐火物屑を塊鉱石の質量比率が相対的に高い鉱石原料a-1にのみ混合したことで、融着帯でのＭｇＯ−Ｃ耐火物屑の溶解が最も進行し、未溶解耐火物屑による炉下部への通気阻害が起きにくくなったためであると考えられる。また、発明例６、１０、１１では、ＭｇＯ−Ｃ耐火物屑を鉱石原料a-1およびa-2に混合したが、鉱石原料a-1およびa-2への混合比率を同等にし若しくは塊鉱石の質量比率が相対的に高い鉱石原料a-1の方に多く混合したことで、発明例４に次いで、融着帯でのＭｇＯ−Ｃ耐火物屑の溶解が進行し、未溶解耐火物屑による炉下部への通気阻害が起きにくくなったためであると考えられる。すなわち、発明例４〜６、１０、１１は、ＭｇＯ−Ｃ耐火物屑の混合量は同じであるが、鉱石原料a-1へのＭｇＯ−Ｃ耐火物屑の混合割合でいうと発明例４＞発明例６，１０，１１＞発明例５であり、この順にＭｇＯ−Ｃ耐火物屑が溶解しやすい（未溶解耐火物屑が少ない）ため、コークス比に上記のような差が生じたものと考えられる。
発明例７ではＭｇＯ−Ｃ耐火物屑を鉱石原料a-1にのみ混合したが、混合量が４５ｋｇ／ｔと多いため未溶解の耐火物屑による炉下部への通気阻害が生じたものと考えられ、コークス比が３４９ｋｇ／ｔまで増加した。
On the other hand, in Invention Examples 4 to 6, 10 and 11, the mixed amount of MgOC refractory waste is 25 kg / t, and the ore raw material a-1, the ore raw material a-2, the ore raw material a-1 and a-2, respectively. Mixed in. Among these invention examples, the coke ratio of Invention Example 4 in which MgO-C refractory waste was mixed only with the ore raw material a-1 was the lowest at 347 kg / t, and MgOC refractory waste was used as the ore raw material a-1. And a-2, the coke ratio of Invention Examples 6, 10 and 11 mixed so that the mixing ratio is ore raw material a-1 ≥ ore raw material a-2 is 348 kg / t, which is the next lowest, and MgOC fire resistance. The coke ratio of Invention Example 5 in which the debris was mixed only with the ore raw material a-2 was the highest at 349 kg / t. This is because, in Invention Example 4, MgO-C refractory waste is mixed only with the ore raw material a-1 having a relatively high mass ratio of lump ore, so that MgO-C refractory waste is melted in the cohesive zone. It is considered that this is because the above progressed most and the obstruction of ventilation to the lower part of the furnace due to undissolved refractory waste became less likely to occur. Further, in Invention Examples 6, 10 and 11, MgOC refractory waste was mixed with the ore raw materials a-1 and a-2, but the mixing ratio with the ore raw materials a-1 and a-2 was made the same or a lump. By mixing a large amount of the ore raw material a-1, which has a relatively high mass ratio of ore, with the ore raw material a-1, the dissolution of MgOC refractory debris in the cohesive zone progresses following Invention Example 4, and the undissolved refractory It is considered that this is because the airflow to the lower part of the furnace is less likely to be obstructed by the debris. That is, in Invention Examples 4 to 6, 10 and 11, the mixing amount of MgOC refractory waste is the same, but in terms of the mixing ratio of MgOC refractory waste to the ore raw material a-1, Invention Example 4 > Invention Examples 6, 10 and 11> Invention Example 5 in which MgO-C refractory debris is easily dissolved (the amount of undissolved refractory debris is small), so that the coke ratio has the above difference. it is conceivable that.
In Invention Example 7, MgOC refractory waste was mixed only with the ore raw material a-1, but it is considered that the undissolved refractory waste hindered the ventilation to the lower part of the furnace because the mixing amount was as large as 45 kg / t. The coke ratio increased to 349 kg / t.
一方、ＭｇＯ源としてブルーサイトを鉱石原料a-1にのみ混合した比較例１、２、同じく鉱石原料a-1およびa-2に混合した比較例７、８では、融着帯において、ＭｇＯが未還元状態のＦｅＯに固溶して高融点化合物を形成したことによる通気性の改善効果はあるが、ＭｇＯ源（ブルーサイト）はＭｇＯ−Ｃ耐火物屑のように高融点ではないため、融着層においてＭｇＯ源により粒子間空隙率が高められる効果が得られず、そのため発明例１〜１１と比較すると通気改善効果が低く、コークス比は３５１ｋｇ／ｔ以上となった。
ＭｇＯ源としてドロマイトを鉱石原料a-1にのみ混合した比較例３、４、同じく鉱石原料a-1およびa-2に混合した比較例９、１０では、スラグボリュームの増加による通気悪化の影響により、コークス比は３５２ｋｇ／ｔ以上となった。
ＭｇＯ源としてマグネサイトを鉱石原料a-1にのみ混合した比較例５、６、同じく鉱石原料a-1およびa-2に混合した比較例１１、１２では、塊状帯における粉化の進行により通気が悪化したため、コークス比は３５２ｋｇ／ｔ以上となった。
On the other hand, in Comparative Examples 1 and 2 in which bluesite was mixed only with the ore raw material a-1 as an MgO source, and Comparative Examples 7 and 8 in which bluesite was mixed with the ore raw materials a-1 and a-2, MgO was mixed in the cohesive zone. Although there is an effect of improving air permeability by solidifying in unreduced FeO to form a high melting point compound, the MgO source (blue ore) does not have a high melting point like MgO-C refractory waste, so it is melted. In the layering, the effect of increasing the interparticle void ratio by the MgO source could not be obtained, and therefore the effect of improving air permeability was lower than that of Examples 1 to 11, and the coke ratio was 351 kg / t or more.
In Comparative Examples 3 and 4 in which dolomite was mixed only with the ore raw material a-1 as an MgO source, and Comparative Examples 9 and 10 in which dolomite was also mixed with the ore raw materials a-1 and a-2, due to the influence of deterioration of ventilation due to an increase in slag volume. The coke ratio was 352 kg / t or more.
In Comparative Examples 5 and 6 in which magnesite was mixed only with the ore raw material a-1 as an MgO source, and in Comparative Examples 11 and 12 in which the magnesite was also mixed with the ore raw materials a-1 and a-2, aeration was performed due to the progress of pulverization in the massive zone. The coke ratio became 352 kg / t or more.
Claims (6)
鉱石原料に混合する副原料の少なくとも一部が、塊状のＭｇＯ−Ｃ系廃耐火物であることを特徴とする高炉操業方法。 It is a blast furnace operation method in which at least a part of the ore raw material is mixed with an auxiliary raw material and charged into the furnace.
A method for operating a blast furnace, characterized in that at least a part of the auxiliary raw material mixed with the ore raw material is a massive MgOC-based waste refractory.
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