JP4792797B2 - Method of charging ores containing high crystal water into a bell-less blast furnace - Google Patents
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本発明は、鉱石を2バッチに分割して装入するベルレス高炉における鉱石の装入方法に関し、詳細には結晶水を3.5質量%以上含有する高結晶水含有鉱石の各バッチでの装入比率を微粉炭吹込量に応じて調整することにより、高炉の通気性を悪化させることなく、かつ、高結晶水含有鉱石を安定使用できる鉱石の装入方法に関する。 The present invention relates to a method for charging ores in a bell-less blast furnace in which ores are divided and charged in two batches, and more specifically, the high-crystal water-containing ores containing 3.5% by mass or more of crystal water are charged in each batch. The present invention relates to an ore charging method capable of stably using ore containing high crystal water without deteriorating the air permeability of the blast furnace by adjusting the charging ratio according to the amount of pulverized coal injected.
高炉操業においては、 一般に、炉上部から還元材および熱源としてのコークス、ならびに鉄源としての焼結鉱、 ペレットおよび塊鉱石など(以下、これらの鉄源を「鉱石」と記す)が交互に層状に装入され、炉下部の羽口から熱風が送風されると同時に微粉炭などが吹き込まれる。なお、微粉炭の吹込量は、通常は銑鉄1t(トン)あたりの吹込み質量(kg)で表され、本発明では(kg/t)にて表示する。 In blast furnace operation, in general, coke as a reducing material and heat source from the upper part of the furnace, and sintered ore, pellets and lump ore as iron sources (hereinafter these iron sources are referred to as “ores”) are alternately layered. The hot air is blown from the tuyeres at the bottom of the furnace and pulverized coal is blown in at the same time. Note that the amount of pulverized coal blown is usually expressed in terms of blown mass (kg) per 1 t (tons) of pig iron, and is expressed in (kg / t) in the present invention.
高炉の安定操業を維持するためには、良好な通気性を確保し、炉内ガス流れの安定化(すなわち、安定した中心ガス流および炉壁ガス流の確保)が必要である。炉内における通気性は、主として装入原料(コークスおよび鉱石)の性状、粒度および装入量により大きく影響されるが、さらに、炉頂からの原料の装入方法、つまり、炉内に装入する原料の分布状況(以下、「装入物分布」とも記す)によっても大きく左右される。 In order to maintain the stable operation of the blast furnace, it is necessary to ensure good air permeability and stabilize the gas flow in the furnace (that is, secure a stable central gas flow and furnace wall gas flow). The air permeability in the furnace is largely influenced by the properties of the raw materials (coke and ore), the particle size, and the amount of charge. In addition, the raw material is charged from the top of the furnace, that is, charged into the furnace. The distribution of raw materials (hereinafter also referred to as “charge distribution”) greatly depends.
この装入物分布の制御については、従来から、高炉の半径方向における鉱石とコークスの質量比(以下、「O/C 」とも記す)の制御、あるいは、焼結鉱などの鉄源原料の炉半径方向における粒度偏差(例えば、炉中心部に粗粒を分布させ、炉壁部に細粒を分布させる)の制御が最もよく用いられている。 これらの装入物分布調整により、安定した中心流および適度の周辺流を確保することができる。 As for the control of the charge distribution, conventionally, the control of the mass ratio of ore and coke in the radial direction of the blast furnace (hereinafter also referred to as “O / C”), or the furnace of the iron source material such as sintered ore. Control of particle size deviation in the radial direction (for example, coarse particles are distributed in the furnace center and fine particles are distributed in the furnace wall) is most often used. By adjusting the distribution of these charges, a stable central flow and a moderate peripheral flow can be secured.
例えば、ベルレス高炉の場合、粒度調整により安定したガス流れを得るために、1層として装入される鉱石を2バッチ以上に分割し、粒度別に装入する方法が採られる。また、第1バッチの装入では炉中心部におけるO/Cを小さくするように装入し、第2バッチの鉱石中に細粒原料、熱間性状の劣る原料などを混合して炉壁部に装入すると、性状の劣る原料を使用しながらであっても、安定したガス流れを得ることができる。 For example, in the case of a bell-less blast furnace, in order to obtain a stable gas flow by adjusting the particle size, a method is adopted in which ore charged as one layer is divided into two or more batches and charged according to particle size. In addition, in the first batch charging, the O / C in the center of the furnace is charged to be small, and the finer raw material, the raw material with poor hot properties, etc. are mixed in the second batch ore, and the furnace wall portion. When the material is charged, a stable gas flow can be obtained even while using a raw material with poor properties.
さらに、近年、コスト合理化などを目的として高結晶水含有鉱石(結晶水含有率が3.5質量%以上の鉱石)を使用するようになってきている。 Further, in recent years, ore with a high crystal water content (ores with a crystal water content of 3.5% by mass or more) has been used for the purpose of cost rationalization.
例えば、特許文献1には、鉄鉱石中に多結晶水含有鉄原料を予め混合して装入するかまたは、単独で多結晶水含有鉄原料を装入する高炉操業方法が開示されている。この方法は、微粉炭吹込量の増加にともなう炉頂ガス温度の上昇を、鉱石中の結晶水の加熱および蒸発に要する熱により抑制する方法である。 For example, Patent Document 1 discloses a blast furnace operating method in which a polycrystalline water-containing iron raw material is mixed and charged in advance in iron ore, or a polycrystalline water-containing iron raw material is charged alone. This method is a method for suppressing the rise in the furnace top gas temperature accompanying the increase in the amount of pulverized coal injection by the heat required for heating and evaporation of the crystal water in the ore.
また、特許文献2には、熱流比(高炉シャフト部におけるガス単位熱量に対する固体単位熱量の比)が0.80以下の高炉の操業方法であって、粒度構成は5mm以上の粒子が80質量%以上、結晶水含有率が3.5質量%以上の塊鉱石を主原料の一部として高炉へ装入することにより、炉頂ガス温度を低下させる操業方法が開示されている。ここで開示された方法は、熱流比の値に応じて高結晶水含有鉱石の装入量を調整することにより、炉頂ガス温度をコントロールするものである。
さらに、特許文献3には、結晶水3%以上を有する多孔質塊鉱石を使用するに際して、3mm以下の粒度を1%以下にした多孔質塊鉱石と焼結鉱とを高炉炉内に装入する操業方法、および焼結鉱の還元粉化指数(JIS M 8720で規定される還元後の粉化率(−3mm%)を意味し、「RDI」と略記する)、炉内の低温還元域における装入物の滞留時間に応じて前記塊鉱石の使用量を調整する操業方法が開示されている。 Furthermore, in Patent Document 3, when using a porous block ore having a crystal water of 3% or more, a porous block ore having a particle size of 3 mm or less and 1% or less and a sintered ore are charged into a blast furnace furnace. Operation method, and reduced pulverization index of sintered ore (meaning pulverization rate after reduction (-3 mm%) defined by JIS M 8720, abbreviated as “RDI”), low temperature reduction zone in furnace Discloses an operation method for adjusting the amount of the lump ore used according to the residence time of the charge.
しかしながら、上記の特許文献1〜3に開示された方法においては、近年、吹込量が増大し、一般に炉内の通気性を悪化させる傾向にある微粉炭吹込量の程度に応じた高結晶水含有鉱石の効果的な装入方法について全く言及されていない。 However, in the methods disclosed in Patent Documents 1 to 3 above, in recent years, the amount of high crystallization water contained in accordance with the degree of the amount of pulverized coal injection that tends to increase the amount of blown air and generally deteriorate the air permeability in the furnace. There is no mention of an effective method of charging ore.
前記のとおり、高結晶水含有鉱石の高炉使用技術において、炉頂温度の抑制、塊状帯および熱保存帯の調整方法を開示した文献は数多く見られる。しかし、高結晶水含有鉱石は、高炉で一般的に使用される鉱石に比べて、RDIの値や、高炉炉下部での通気抵抗を指数化した非特許文献1に記載のKS値がともに高く、現実には高炉で安定して使用増加を図ることが困難な原料である。なぜなら、炉内通気性が悪化すれば高炉の安定操業の継続が困難となり、計画生産量を維持することはできないからである。 As described above, in the blast furnace use technology for ore containing high crystal water, there are many documents disclosing methods for suppressing the furnace top temperature and adjusting the massive zone and the heat preservation zone. However, the ore containing high crystal water has a higher RDI value and a higher KS value described in Non-Patent Document 1 in which the ventilation resistance at the lower part of the blast furnace is indexed, compared to ores generally used in a blast furnace. In reality, it is a raw material that is difficult to increase in use stably in a blast furnace. This is because if the air permeability in the furnace deteriorates, it is difficult to continue the stable operation of the blast furnace, and the planned production volume cannot be maintained.
したがって、炉内通気性の悪化は避けなければならず、今後、微粉炭吹込の拡大を図っていくにあたり、微粉炭吹込量の増加と高結晶水含有鉱石の使用量増加との両立は困難になると予想される。 Therefore, deterioration of furnace breathability must be avoided, and it will be difficult to increase both the amount of pulverized coal injection and the amount of ore containing high crystal water when expanding the pulverized coal injection in the future. It is expected to be.
すでに述べたとおり、特許文献1には、微粉炭吹込量の増加にともなう炉頂温度上昇対策としての高結晶水含有鉱石の使用量増加技術が開示されているが、この技術は高炉操業の改善要素に乏しく、高炉の通気性悪化を惹起するおそれが高い。 As already mentioned, Patent Document 1 discloses a technique for increasing the amount of ore containing high crystal water as a countermeasure for increasing the temperature at the top of the furnace accompanying the increase in the amount of pulverized coal injection, but this technique improves the operation of the blast furnace. There are few elements and there is a high risk of causing deterioration of the air permeability of the blast furnace.
特許文献2に開示された方法もまた、前記特許文献1に開示された方法と同様に、単に高結晶水含有鉱石の装入量を増加させて炉頂ガス温度を低下させる方法であり、炉内通気性悪化に対する配慮がなされておらず、現実的方法とは言い難い。
Similarly to the method disclosed in Patent Document 1, the method disclosed in
さらに、特許文献3に開示された方法は、焼結鉱のRDIの値および炉内の低温還元域における装入物の滞留時間に応じて高結晶水含有鉱石の使用量を調整する方法であるが、RDIの値は日々変動するものであり、その変動に応じて鉱石の使用量を調整するのは現実的ではない。また、炉内の低温還元帯の位置を日々のピッチできめ細かく測定することも困難である。 Furthermore, the method disclosed in Patent Document 3 is a method of adjusting the amount of ore containing high crystal water according to the RDI value of the sintered ore and the residence time of the charge in the low temperature reduction zone in the furnace. However, the value of RDI fluctuates from day to day, and it is not realistic to adjust the amount of ore used according to the fluctuation. It is also difficult to meticulously measure the position of the low-temperature reduction zone in the furnace with a daily pitch.
また、通気性を悪化させやすい微粉炭吹込量の増大下にあって、通気性を阻害する高結晶水含有鉱石装入量をいかに増加させるかといった視点においても、何らの示唆も与えていない。 Further, no suggestion is given from the viewpoint of increasing the amount of ore charging containing high crystal water that impairs the air permeability under the increase in the amount of pulverized coal injection that tends to deteriorate the air permeability.
本発明は、上記の問題に鑑みてなされたものであって、その課題は、微粉炭吹込量に応じて、高結晶水含有鉱石の装入量を鉱石の各バッチで調整することにより、微粉炭吹込量が変化した場合においても、高炉内の通気性および荷下がりを阻害することなく、高結晶水含有鉱石を安定して効果的に装入使用できるベルレス高炉への高結晶水含有鉱石の装入方法を提供することにある。 The present invention has been made in view of the above-mentioned problems, and the problem is that by adjusting the charging amount of ore containing high crystal water in each batch of ore according to the amount of pulverized coal injection, Even when the amount of coal injection changes, the high crystal water-containing ore to the bell-less blast furnace that can stably and efficiently use ore the high crystal water-containing ore without hindering air permeability and unloading in the blast furnace. It is to provide a charging method.
本発明者らは、前記の課題を解決するために、後述する高温荷重軟化試験、およびベルレス高炉に高結晶水含有鉱石を装入する試験操業を行ってその結果を解析し、下記の(a)〜(d)に示す知見を得て、本発明を完成させた。 In order to solve the above-mentioned problems, the present inventors conducted a high-temperature load softening test described later and a test operation in which a high-crystal-water-containing ore is charged into a bell-less blast furnace, and analyzed the results. ) To (d) were obtained and the present invention was completed.
(a)鉱石層中への高結晶水含有鉱石の装入比率の増加にともなって、高温通気抵抗((非特許文献1に記載のKS値)は上昇し、したがって、高炉下部における通気性は悪化する。 (A) With an increase in the charging ratio of the high crystal water-containing ore into the ore layer, the high temperature ventilation resistance ((KS value described in Non-Patent Document 1)) increases, and therefore the permeability at the bottom of the blast furnace is Getting worse.
(b)鉱石を2バッチに分割して高炉内に装入する場合に、高結晶含有鉱石をいずれか片方のバッチにのみ装入するよりも、両方のバッチに分割して装入する方が良好な高炉内通気性を確保できる。 (B) When ore is divided into two batches and charged into the blast furnace, it is better to divide and charge the high crystal content ore into both batches than to charge only one of the batches. Good air permeability in the blast furnace can be secured.
(c)高結晶水含有鉱石を2バッチに分割して装入する際に、第1バッチにより高結晶水含有鉱石を炉半径方向に対して広範囲に、かつその層厚を薄く装入し、第2バッチにより残りの高結晶水含有鉱石を炉壁部に集中的に装入することにより、高炉内の通気性を阻害することなく、多量の高結晶水含有鉱石を安定的に使用できる。 (C) When ore containing high-crystal water-containing ore divided into two batches, the first batch contains high-crystal water-containing ore in a wide range with respect to the radial direction of the furnace and with a thin layer thickness. By intensively charging the remaining high crystal water-containing ore into the furnace wall by the second batch, a large amount of high crystal water-containing ore can be stably used without impairing the air permeability in the blast furnace.
(d)高炉内の良好な通気性を確保するためには、微粉炭吹込量PCR(kg/pt)に応じて、第1バッチで装入する高結晶水含有鉱石の装入比率A(質量%)および第2バッチで装入する高結晶水含有鉱石の装入比率B(質量%)を、それぞれ下記(1)式および(2)式により表される関係を満足するように調整することが好ましい。 (D) In order to ensure good air permeability in the blast furnace, the charging ratio A (mass of high crystal water containing ore charged in the first batch according to the pulverized coal injection amount PCR (kg / pt) %) And the charging ratio B (mass%) of the ore containing high crystal water charged in the second batch so as to satisfy the relationship represented by the following formulas (1) and (2), respectively. Is preferred.
A≦−0.05×PCR+15 ・・・・(1)
B≦3 ・・・・・・・・・・(2)
本発明は、上記の知見に基づいて完成されたものであり、その要旨は、下記の(1)および(2)に示すベルレス高炉への高結晶水含有鉱石の装入方法にある。
A ≦ −0.05 × PCR + 15 (1)
B ≦ 3 (2)
The present invention has been completed based on the above findings, and the gist of the present invention lies in the method for charging ores containing high crystal water into the bell-less blast furnace shown in the following (1) and (2).
(1)鉱石を2バッチに分割して、炉内半径方向の全範囲にわたって第1バッチを、炉壁部に第2バッチを装入するベルレス高炉への鉱石装入方法において、結晶水含有率が3.5質量%以上である高結晶水含有鉱石をそれぞれのバッチに分割して装入することを特徴とするベルレス高炉への高結晶水含有鉱石の装入方法(以下、「第1発明」とも記す)。 (1) In the method for charging ores into a bell-less blast furnace in which the ore is divided into two batches, and the first batch is charged over the entire range in the radial direction of the furnace and the second batch is charged into the furnace wall, A method for charging high-crystal water-containing ore into a bell-less blast furnace, characterized in that the high-crystal water-containing ore having a content of 3.5% by mass or more is divided and charged into respective batches (hereinafter referred to as “first invention”). ").
(2)鉱石を2バッチに分割して、炉内半径方向の全範囲にわたって第1バッチを、炉壁部に第2バッチを装入するベルレス高炉への鉱石装入方法において、微粉炭吹込量に応じて、第1バッチおよび第2バッチで装入する結晶水含有率が3.5質量%以上である高結晶水含有鉱石の装入比率をそれぞれ下記(1)式および(2)式により表される関係を満足するように調整することを特徴とするベルレス高炉への高結晶水含有鉱石の装入方法(以下、「第2発明」とも記す)。
(2) In the method of charging ore into the bell-less blast furnace where the ore is divided into two batches, and the first batch is charged over the entire range in the radial direction of the furnace and the second batch is charged into the furnace wall, In accordance with the following formulas (1) and (2), the charging ratio of the ore containing high crystallization water with a crystallization water content of 3.5% by mass or more charged in the first batch and the second batch, respectively. A method of charging ore containing high crystal water into a bell-less blast furnace, which is adjusted so as to satisfy the expressed relationship (hereinafter also referred to as “second invention”).
A≦−0.05×PCR+15 ・・・・(1)
B≦3 ・・・・・・・・・・(2)
ここで、Aは、鉱石第1バッチで装入する高結晶水含有鉱石量が全装入鉱石量に対して占める比率(質量%)、Bは、鉱石第2バッチで装入する高結晶水含有鉱石量が全装入鉱石量に対して占める比率(質量%)、そしてPCRは、高炉への微粉炭吹込量(kg/pt)を表す。なお、ptは、銑鉄1t(トン)を表す。
A ≦ −0.05 × PCR + 15 (1)
B ≦ 3 (2)
Here, A is the ratio (% by mass) of the amount of ore containing high crystal water charged in the first batch of ore to the total amount of ore charged, and B is the high crystal water charged in the second batch of ore. The ratio (mass%) that the amount of containing ore occupies with respect to the amount of all ores charged, and PCR represent the amount of pulverized coal injected into the blast furnace (kg / pt). In addition, pt represents pig iron 1t (ton).
本発明において、「高結晶水含有鉱石」とは、前記のとおり結晶水含有率が3.5質量%以上である鉱石を意味する。 In the present invention, “high crystal water-containing ore” means an ore having a crystal water content of 3.5% by mass or more as described above.
なお、以下の説明においては、「質量%」を単に「%」とも表記する。 In the following description, “mass%” is also simply expressed as “%”.
本発明の方法によれば、ベルレス高炉への微粉炭吹込量に応じて、高結晶水含有鉱石の装入量を鉱石の各バッチで適正量に調整して装入することができるので、微粉炭吹込量が変化する操業においても、高炉内の良好なガス流れおよび荷下がりを確保しながら、多量の高結晶水含有鉱石を安定して効果的に使用できる。 According to the method of the present invention, according to the amount of pulverized coal injected into the bell-less blast furnace, it is possible to adjust the charging amount of ore containing high crystal water to an appropriate amount in each batch of ore. Even in an operation where the amount of coal injection changes, a large amount of ore containing high crystal water can be stably and effectively used while ensuring a good gas flow and unloading in the blast furnace.
本発明は、前記のとおり、高結晶水含有鉱石を2バッチに分割して、炉内半径方向の全範囲にわたって第1バッチを、炉壁部に第2バッチを装入するベルレス高炉への結晶水含有率が3.5質量%以上である高結晶水含有鉱石の装入方法であり、好ましくは、第1バッチで装入する高結晶水含有鉱石の装入比率を、高炉への微粉炭吹込量により定まる装入比率の上限値以下とし、かつ、第2バッチでの装入比率を3%以下するように調整するベルレス高炉への高結晶水含有鉱石の装入方法である。本発明の高結晶水含有鉱石の装入方法について、以下にさらに詳細に説明する。
In the present invention, as described above, the ore containing high crystal water is divided into two batches, and the first batch is charged over the entire range in the radial direction of the furnace, and the second batch is charged into the furnace wall. It is a method for charging high crystal water-containing ore having a water content of 3.5% by mass or more. Preferably, the charging ratio of the high crystal water-containing ore charged in the first batch is changed to pulverized coal in the blast furnace. This is a method for charging ore containing high crystal water into a bell-less blast furnace that is adjusted to be equal to or less than the upper limit value of the charging ratio determined by the blowing amount and to be 3% or less in the second batch. The method for charging the ore containing high crystal water according to the present invention will be described in more detail below.
(1)高結晶水含有鉱石の高温通気特性および装入比率の影響
高結晶水含有鉱石の通気特性を把握するため、竪型電気炉を用いて実験室規模の高温荷重軟化試験を行い、鉱石の高温通気特性を調査した。試験条件の詳細は、前記の非特許文献1に記載されているので、ここでは概要のみを述べる。
(1) Effect of high-temperature water-containing ore on high-crystal water-containing ores and charging ratio To understand the air-flow characteristics of ores containing high-crystal water, laboratory-scale high-temperature load softening tests were conducted using a vertical electric furnace. The high temperature aeration characteristic of was investigated. Since the details of the test conditions are described in Non-Patent Document 1, only the outline is described here.
底部にガスの流通および溶融物の滴下のための複数の孔を有する内径70mmの黒鉛坩堝内に、試料となる粒径10〜15mmのコークスを下層に、また、粒径15〜20mmの鉱石を上層にして、鉱石とコークスの質量比(O/C)が所定の値となるように装入し、竪型電気炉内に配置する。これらの試料に、時間とともにCO濃度が24から45%まで順次上昇し、CO2濃度が23から0%まで順次低下する還元ガスを50NL/分の流量で流しながら、また、時間とともに0から0.1MPaまで増加する荷重をかけながら、6時間で1600℃まで昇温する昇温荷重還元試験を行い、その間の試料層における圧力損失およびその層厚の経時変化を測定した。上記の試験により得られた圧力損失および試料の層厚を用いて通気抵抗を求め、この通気抵抗を、1000℃から試験終了温度(Tf)までの温度範囲にわたって積分し、高温通気抵抗(KS値)を求めた。 In a graphite crucible with an inner diameter of 70 mm having a plurality of holes for gas flow and dripping of melt at the bottom, a sample of coke with a particle size of 10 to 15 mm is used as a lower layer, and an ore with a particle size of 15 to 20 mm. In the upper layer, the ore and coke mass ratio (O / C) is charged so as to have a predetermined value, and is placed in a vertical electric furnace. In these samples, a reducing gas in which the CO concentration gradually increases from 24 to 45% with time and the CO 2 concentration gradually decreases from 23 to 0% flows at a flow rate of 50 NL / min. While applying a load increasing to 1 MPa, a heating load reduction test was performed in which the temperature was raised to 1600 ° C. in 6 hours, and the pressure loss and the layer thickness change over time of the sample layer were measured. The airflow resistance is obtained by using the pressure loss obtained by the above test and the layer thickness of the sample, and this airflow resistance is integrated over a temperature range from 1000 ° C. to the test end temperature (Tf) to obtain a high temperature airflow resistance (KS value). )
図1は、高温通気抵抗(KS値)の算出方法を示す図である。高温通気抵抗(KS値)は、その値が小さいほど鉱石の軟化から溶融滴下に至るまでの通気抵抗が小さいことを意味する。したがって、KS値が大きい鉱石を炉内に装入した場合には、高炉下部の融着帯における通気性の悪化が予想される。 FIG. 1 is a diagram illustrating a method for calculating a high temperature ventilation resistance (KS value). The high temperature ventilation resistance (KS value) means that the smaller the value, the smaller the ventilation resistance from the softening of the ore to the melt dripping. Therefore, when ores having a large KS value are charged into the furnace, the air permeability in the fusion zone at the bottom of the blast furnace is expected to deteriorate.
表1に、通常の鉱石と高結晶水含有鉱石とについて、上記の試験により得られたKS値およびRDIを比較して示した。 Table 1 shows a comparison of the KS values and RDIs obtained by the above tests for ordinary ores and high crystal water-containing ores.
同表に示されるとおり、高結晶水含有鉱石Aは還元粉化しやすく、また高温通気性に非常に劣る。したがって、このように高炉の通気性を阻害しやすい高結晶水含有鉱石を使用する際には、その特性を十分に考慮し、その特性に応じて炉内半径方向の適正な領域に適正な量だけ装入することが必要である。また、今後、微粉炭吹込量は150〜200kg/ptの水準へとますます増加してゆくことが予想されることから、炉内通気性が全体として悪化する方向にある中で、微粉炭吹込量の水準に応じた高結晶水含有鉱石の効果的装入方法を確立する必要がある。 As shown in the table, the ore A containing high crystal water is easily reduced to powder and is very inferior in high-temperature air permeability. Therefore, when using ores with high crystal water content that tends to hinder the air permeability of the blast furnace in this way, fully consider its characteristics, and in accordance with the characteristics, an appropriate amount in an appropriate area in the radial direction of the furnace It is only necessary to charge. In addition, in the future, the amount of pulverized coal injection is expected to increase further to the level of 150 to 200 kg / pt. It is necessary to establish an effective charging method for ore containing high crystal water according to the level of quantity.
そこで、高炉での微粉炭吹込量を100kg/ptと想定してO/Cの値を4.2に設定し、高結晶水含有鉱石Aの装入比率を変化させて、昇温荷重還元試験を行い、KS値に及ぼす影響を調査した。なお、高結晶水含有鉱石の装入比率は、黒鉛坩堝中に上層として装入する焼結鉱中における高結晶水含有鉱石の配合比率を変更することにより変化させた。 Therefore, assuming that the amount of pulverized coal injection in the blast furnace is 100 kg / pt, the O / C value is set to 4.2, and the charging ratio of the ore A containing high crystal water is changed, and the heating load reduction test is performed. The effect on the KS value was investigated. The charging ratio of the high crystal water-containing ore was changed by changing the blending ratio of the high crystal water-containing ore in the sintered ore charged as an upper layer in the graphite crucible.
試験および評価結果を表2に示した。 The test and evaluation results are shown in Table 2.
同表に示された結果から、高結晶水含有鉱石の装入比率が増加するにつれてKS値は上昇し、装入比率が14%の場合には、高結晶水含有鉱石の比率が4%の場合に比べてKS値は50%以上、上昇することがわかる。 From the results shown in the table, the KS value increases as the charging ratio of the high crystal water containing ore increases. When the charging ratio is 14%, the ratio of the high crystal water containing ore is 4%. It can be seen that the KS value increases by 50% or more compared to the case.
したがって、実高炉においても、高結晶水含有鉱石の装入比率が高くなると、炉下部の融着帯領域において通気性が悪化し、良好な炉内ガス流れが阻害される。 Accordingly, even in the actual blast furnace, when the charging ratio of the ore containing high crystal water becomes high, the air permeability deteriorates in the cohesive zone region at the lower part of the furnace, and good gas flow in the furnace is inhibited.
(2)高結晶水含有鉱石の分割装入方法
本発明者は、さらに、実炉操業の経験および試験操業に基づき、高結晶水含有鉱石の各バッチへの分割方法について検討を行い、高結晶水含有鉱石を片方のバッチに装入するよりも、両バッチに分割して装入する方が高炉の通気性確保の面から好ましいことを見出した。
(2) Method of dividing and charging high crystal water-containing ore The inventor further examined the method for dividing high crystal water-containing ore into batches based on experience in actual furnace operation and test operation. The present inventors have found that it is preferable to divide and charge the water-containing ore into both batches in order to ensure the air permeability of the blast furnace, rather than charging it into one batch.
その理由は、下記に説明するとおりである。すなわち、高結晶水含有鉱石は、前記のとおり高温通気特性に劣るため、荷下がりにより高炉下部に達したとき、炉下部の融着帯領域において通気性を悪化させ、その結果、炉下部における圧力損失を増大させる。 The reason is as described below. That is, the ore containing high crystal water is inferior to the high temperature aeration characteristics as described above, so when it reaches the lower part of the blast furnace due to unloading, it deteriorates the air permeability in the cohesive zone region of the lower part of the furnace, and as a result, the pressure in the lower part of the furnace Increase loss.
したがって、その対策として、炉内半径方向の極力広範な領域にわたって高結晶水含有鉱石を、その層厚を薄くして装入することにより、高炉下部における通気性悪化への影響を低減することができる。また、高炉は炉壁流を適度にコントロールする目的で、細粒コークスや細粒焼結鉱を炉壁部に配置するように装入する場合があるが、高温通気抵抗の高い、すなわち高温通気特性の悪い高結晶水含有鉱石の少量を炉壁部に集中して装入することによっても、細粒コークスや細粒焼結鉱の炉壁部への装入時と同様の効果を得ることができる。 Therefore, as a countermeasure, it is possible to reduce the influence on deterioration of air permeability in the lower part of the blast furnace by introducing ore with high crystal water content over a wide area as much as possible in the radial direction of the furnace, by reducing the layer thickness. it can. In addition, blast furnaces are sometimes charged with fine coke and fine-grained sintered ore placed on the furnace wall for the purpose of appropriately controlling the furnace wall flow. The same effect as when charging fine coke or fine sintered ore into the furnace wall can be obtained by concentrating and charging a small amount of high-crystal water-containing ore with poor characteristics into the furnace wall. Can do.
図2は、高結晶水含有鉱石の高炉内装入分布の縦断面を模式的に示す図である。 FIG. 2 is a diagram schematically showing a longitudinal section of the distribution of high crystal water-containing ore in the blast furnace interior.
同図に示されるとおり、コークス層1の上部に、炉内半径方向の広範囲にわたって、高結晶水含有鉱石4を配合した鉱石第1バッチが装入され、第1バッチ鉱石層2が形成される。第1バッチ鉱石層2中の高結晶水含有鉱石4は、高炉半径方向の比較的広範な領域に、薄い層厚で分布堆積する。そして、炉壁部に形成された第2バッチ鉱石層3中には少量の高結晶水含有鉱石4が分布する。その結果、安定した中心部ガス流および適度の炉壁部ガス流が確保される。
As shown in the figure, the first
以上のとおり、鉱石を2バッチに分け、その第1バッチで炉半径方向に対して、高結晶水含有鉱石を広く薄く、次の第2バッチで炉壁部に残りの高結晶水含有鉱石を集中して装入することにより、多量の高結晶水含有鉱石を高炉の通気性に悪影響を及ぼすことなく、安定して使用できる。 As described above, the ore is divided into two batches, and in the first batch, the ore containing high crystal water is wide and thin with respect to the radial direction of the furnace, and the remaining high crystal water containing ore is placed on the furnace wall in the next second batch. By charging in a concentrated manner, a large amount of ore containing high crystal water can be used stably without adversely affecting the air permeability of the blast furnace.
また、高炉における微粉炭多量吹込み操業にあっては、上記の装入を継続しながら、微粉炭吹込量の増加に応じて高結晶水含有鉱石の全装入量を低下させることにより、高結晶水含有鉱石の高炉における安定使用を確保できると推察される。 In addition, in blast furnace mass injection operation in a blast furnace, while continuing the above charging, by reducing the total charging amount of ore containing high crystal water as the pulverized coal injection amount increases, It is assumed that stable use of crystal water-containing ore in the blast furnace can be secured.
そこで、後述するとおり、高炉における試験操業を行って、各装入バッチへの高結晶水含有鉱石の分割比率の効果を調査し、下記の1)〜3)に示す結果を得た。 Therefore, as will be described later, a test operation in a blast furnace was performed, and the effect of the division ratio of the high crystal water-containing ore to each charging batch was investigated, and the results shown in the following 1) to 3) were obtained.
1)高炉内の良好な通気性を確保するためには、微粉炭吹込量PCR(kg/pt)に
応じて、鉱石第1バッチで装入する高結晶水含有鉱石量の全装入鉱石量に対する比率A(%)を(1)式により表される関係を満足するように調整することが好ましい。
1) In order to ensure good air permeability in the blast furnace, the total amount of ore with high crystallization water content ore charged in the first batch of ore according to the pulverized coal injection amount PCR (kg / pt) It is preferable to adjust the ratio A (%) to the ratio so as to satisfy the relationship represented by the formula (1).
A≦−0.05×PCR+15 ・・・・(1)
2)高結晶水含有鉱石の全バッチにおける総装入比率が同じであっても、鉱石第2バッチで装入する高結晶水含有鉱石量の全装入鉱石量に対する比率B(%)が3%以下を満足するように調整することが好ましい。
A ≦ −0.05 × PCR + 15 (1)
2) Even if the total charging ratio in all batches of high-crystal water-containing ore is the same, the ratio B (%) of the high-crystal water-containing ore charged in the second batch of ore to the total charged ore amount is 3 It is preferable to adjust so that it may satisfy% or less.
3)さらに好ましくは、比率B(%)が2%以下となるように調整するのがよく、したがって、比率A(%)が下記(3)式により表される関係を満たすように調整することが一層好ましい。 3) More preferably, the ratio B (%) should be adjusted to be 2% or less. Therefore, the ratio A (%) should be adjusted so as to satisfy the relationship represented by the following formula (3). Is more preferable.
−0.05×PCR+13<A≦−0.05×PCR+15 ・・・・(3)
ここで、さらに、本発明の高結晶水含有鉱石の装入方法を、鉱石を3バッチ以上に分割する装入方法に拡張適用する場合について説明を加える。
−0.05 × PCR + 13 <A ≦ −0.05 × PCR + 15 (3)
Here, the case where the high crystal water containing ore charging method of the present invention is further applied to the charging method for dividing the ore into three batches or more will be described.
まず、高結晶水含有鉱石を各バッチに分割するに当たり、鉱石の最終バッチでは3%以下の鉱石量を装入する。そして、第1バッチから最終バッチの1バッチ前までのバッチにおいては、装入比率A(%)を第1バッチから最終バッチの1バッチ前までにおける高結晶水含有鉱石装入量の合計比率と読み替え、本発明で規定される前記(1)で表される関係を満足するように装入比率A(%)を調整して装入すればよい。 First, in dividing the ore containing high crystal water into each batch, the final ore batch is charged with an ore amount of 3% or less. And in the batch from the first batch to the last batch, the charging ratio A (%) is the total ratio of the ore charging with high crystal water content from the first batch to the last batch one batch. In other words, the charging may be performed by adjusting the charging ratio A (%) so as to satisfy the relationship represented by (1) defined in the present invention.
以降は、上記の装入操作を繰り返すことになるが、操業中における炉内通気性(高炉通気抵抗指数)、スリップ回数などの炉況管理指標の推移状況に応じて、高結晶水含有鉱石の装入比率を微調整すればよい。 Thereafter, the above charging operation is repeated, but depending on the transition status of furnace condition management indices such as furnace permeability (blast furnace ventilation resistance index) and number of slips during operation, The charging ratio may be finely adjusted.
本発明の高結晶水含有鉱石の装入方法による効果を確認するため、炉内容積が4800m3の高炉において微粉炭吹込量120kg/ptの条件下で高結晶水含有鉱石を装入する試験操業を行い、高炉通気性、スリップ発生状況などの操業成績の及ぼす影響を評価した。試験操業は、一条件あたり5日間の連続操業とし、操業結果はその間の平均値を採用した。 In order to confirm the effect of the high crystal water-containing ore charging method of the present invention, the test operation of charging the high crystal water-containing ore in a blast furnace with a furnace internal volume of 4800 m 3 under the condition that the pulverized coal injection amount is 120 kg / pt. We evaluated the effects of operating results such as blast furnace permeability and slip occurrence. The test operation was a continuous operation for 5 days per condition, and the average value during the operation was adopted.
試験操業における操業条件および操業結果を表3に示す。 Table 3 shows operation conditions and operation results in the test operation.
同表において、高炉通気抵抗指数KRは下記(4)式により算出される値であり、KRの値が低いほど高炉内の通気性は良好であることを意味する。 In the table, the blast furnace ventilation resistance index KR is a value calculated by the following equation (4), and the lower the value of KR, the better the air permeability in the blast furnace.
KR=(PB−PT)/L/(kμβρ1-βu2-β) ・・・・(4)
ここで、KRは高炉通気抵抗指数(1/m)、PBおよびPTはそれぞれ送風圧力および炉頂圧力(Pa)、Lは羽口と炉頂間の距離(m)、βおよびkはガス流れの形態などにより定まる定数、μはガスの粘度(Pa・s)、ρはガスの密度(kg/m3)、そしてuは炉内のガス流速(m/s)をそれぞれ表す。
KR = (P B −P T ) / L / (kμ β ρ 1−β u 2−β ) (4)
Where KR is the blast furnace ventilation resistance index (1 / m), P B and P T are the blowing pressure and the top pressure (Pa), L is the distance between the tuyere and the top (m), β and k are A constant determined by the form of the gas flow, μ is the gas viscosity (Pa · s), ρ is the gas density (kg / m 3 ), and u is the gas flow velocity (m / s) in the furnace.
また、同表中の試験結果の評価欄の記号◎、○、△および×による区分の基準は、表3の下欄に記載したとおりである。 In addition, the criteria for classification by symbols ◎, ○, Δ, and x in the test result evaluation column in the same table are as described in the lower column of Table 3.
試験番号2−1〜2−5および2−7〜2−11は、いずれも第1発明で規定する条件を満足する本発明例であり、試験番号2−6および2−12は、比較例である。 Test numbers 2-1 to 2-5 and 2-7 to 2-11 are examples of the present invention that satisfy the conditions specified in the first invention, and test numbers 2-6 and 2-12 are comparative examples. It is.
本発明例においては、いずれも、高炉通気抵抗指数KRは当高炉において許容できる13400(1/m)以下であり、また装入物の荷下がり異常を示すスリップ発生回数も1.6(回/日)以下に抑えられており、炉況は良好に推移した。 In all of the examples of the present invention, the blast furnace ventilation resistance index KR is 13400 (1 / m) or less which is allowable in the blast furnace, and the number of slip occurrences indicating an unloading abnormality of the charge is 1.6 (times / time). The furnace conditions were favorable.
これに対して、比較例においては、高炉通気抵抗指数KRは当高炉においては高めの13800(1/m)に達し、またスリップ発生回数も1.8(回/日)と高めになって、炉況は不安定となった。 On the other hand, in the comparative example, the blast furnace ventilation resistance index KR reached a high 13800 (1 / m) in the blast furnace, and the number of slip occurrences was also increased to 1.8 (times / day). The furnace condition became unstable.
表3の結果を整理することにより、鉱石第1バッチの高結晶水含有鉱石の装入比率A(%)を、前記(1)式で表される関係を満足する範囲に調整すれば、高炉通気抵抗指数KRに大きな影響を及ぼすことなく良好な通気性および荷下がり状況を確保できるので好ましいことが判明した。また、高結晶水含有鉱石の全装入比率が同じであっても、鉱石第2バッチに高結晶水含有鉱石を4%装入した試験番号2−3および2−9の場合には、装入比率が3%以下の試験番号2−1、2−2、2−7および2−8の場合に比較して高炉通気抵抗指数KRが上昇する。したがって、鉱石第2バッチに装入する高結晶水含有鉱石の全装入鉱石に対する比率B(%)を3%以下とすることが好ましいことも判明した。 By arranging the results of Table 3 and adjusting the charging ratio A (%) of the high-crystal water-containing ore of the first batch of ore to a range satisfying the relationship represented by the above formula (1), the blast furnace It was proved preferable because good air permeability and unloading conditions could be secured without greatly affecting the air flow resistance index KR. In the case of Test Nos. 2-3 and 2-9 in which 4% of high-crystal water-containing ore was charged into the second batch of ore even if the total charging ratio of high-crystal water-containing ore was the same, The blast furnace ventilation resistance index KR is increased as compared with the case of test numbers 2-1, 2-2, 2-7, and 2-8 having an input ratio of 3% or less. Accordingly, it has also been found that the ratio B (%) of the high crystallized water-containing ore charged into the second ore batch to the total charged ore is preferably 3% or less.
図3は、表3の結果を整理し、高炉の通気性評価に及ぼす微粉炭吹込量および鉱石第1バッチでの高結晶水含有鉱石装入比率の影響として示した図である。同図中の記号◎、○、△および×は、いずれも、表3の試験結果の評価欄に用いた記号と同義である。同図の結果から、下記の事項が明らかである。 FIG. 3 is a table showing the results of Table 3 as effects of the amount of pulverized coal injection and the ore charging ratio containing high crystal water in the first batch of ore on the blast furnace air permeability evaluation. The symbols ◎, ○, Δ and × in the figure are all synonymous with the symbols used in the test result evaluation column of Table 3. From the results in the figure, the following matters are clear.
すなわち、本発明の背景技術において記載したとおり、コスト合理化の観点から高結晶水含有鉱石の全装入比率(A+B)(%)は、できる限り大きくしたい。しかし、前記のとおり、第1バッチにおける装入比率A(%)は、(1)式により表される関係を満たすように調整することが好ましい。また、第2バッチにおける装入比率B(%)は試験番号2−1、2−2、2−7および2−8の結果に示されるとおり、3%以下とすることが好ましく、さらに好ましくは、試験番号2−1および2−7に示されるとおり、2%以下とするのがよい。 That is, as described in the background art of the present invention, from the viewpoint of cost rationalization, the total charging ratio (A + B) (%) of the ore containing high crystal water is desired to be as large as possible. However, as described above, it is preferable to adjust the charging ratio A (%) in the first batch so as to satisfy the relationship represented by the formula (1). Further, the charging ratio B (%) in the second batch is preferably 3% or less as shown in the results of Test Nos. 2-1, 2-2, 2-7 and 2-8, more preferably As shown in Test Nos. 2-1 and 2-7, it should be 2% or less.
したがって、これらから、第1バッチにおける装入比率A(%)は、下記(3)式により表される関係を満たすように調整することが一層好ましい。 Therefore, it is more preferable to adjust the charging ratio A (%) in the first batch so as to satisfy the relationship represented by the following expression (3).
−0.05×PCR+13<A≦−0.05×PCR+15 ・・・・(3)
なお、上記の一層好ましい範囲を図3中に斜線部で表示した。
−0.05 × PCR + 13 <A ≦ −0.05 × PCR + 15 (3)
The more preferable range described above is indicated by the hatched portion in FIG.
以上に説明したとおり、装入比率3%までの高結晶水含有鉱石は、第2バッチにおいて炉壁部に広く薄く堆積させるので、鉱石自体の高温通気抵抗KS値が高くても高炉下部での通気性の悪化に大きな影響を及ぼすことはない。そして、残りの高結晶水含有鉱石は、鉱石第1バッチにおいて、微粉炭吹込量の値に応じて、つまりO/Cの値に応じて高炉通気性に悪影響を与えない範囲で装入できる。 As explained above, ore containing high crystal water up to a charging ratio of 3% is deposited thinly on the furnace wall in the second batch, so even if the ore itself has a high high temperature ventilation resistance KS value, There is no significant effect on the deterioration of air permeability. The remaining high crystal water-containing ore can be charged in the ore first batch within a range that does not adversely affect the blast furnace air permeability according to the value of the pulverized coal injection amount, that is, according to the value of O / C.
この理由は下記のとおりである。すなわち、高結晶水含有鉱石は高温通気特性に劣るため、炉内半径方向のある特定の領域に集中して装入すると、その領域の通気性が極度に悪化することから、使用比率を増大することができない。これに対して、高結晶水含有鉱石を前記で述べたように鉱石の各バッチを分け、それぞれのバッチにおいて装入することにより炉内半径方向に均一に装入することができるため、半径方向の特定の領域に極度に高い通気抵抗の負荷を与えることがなくなるからである。 The reason for this is as follows. That is, the ore containing high crystal water is inferior in high-temperature aeration characteristics, so if it is concentrated and charged in a specific area in the radial direction of the furnace, the air permeability in that area will be extremely deteriorated, increasing the use ratio. I can't. On the other hand, the ore containing high crystal water can be charged uniformly in the radial direction in the furnace by dividing each batch of ore as described above and charging in each batch, so that the radial direction This is because an extremely high ventilation resistance load is not applied to the specific region.
第2バッチは、通常、炉壁流をコントロールするために細粒原料などを多目に使用する場合が多い。そのため、本発明では、この第2バッチに3%以下の少量の比率の高結晶水含有鉱石を使用することにより、炉壁部ガス流を適度にコントロールしながら高結晶水含有鉱石を使用することができて好ましい。しかしながら、多量の高結晶水含有鉱石を炉壁部に装入すると、炉壁下部での通気性が悪化し、高結晶水含有鉱石の装入比率の増大を図ることは困難となるので、第2バッチでの装入比率は上記の範囲内とすることが好ましい。 In many cases, the second batch often uses fine-grained raw materials to control the furnace wall flow. Therefore, in the present invention, by using a high crystal water content ore in a small proportion of 3% or less in this second batch, the high crystal water content ore is used while appropriately controlling the furnace wall gas flow. Is preferable. However, if a large amount of high crystal water-containing ore is charged into the furnace wall, the air permeability at the bottom of the furnace wall deteriorates and it becomes difficult to increase the charging ratio of the high crystal water-containing ore. The charging ratio in two batches is preferably within the above range.
本発明の鉱石装入方法によれば、ベルレス高炉への微粉炭吹込量に応じて、高結晶水含有鉱石の装入量を鉱石の各バッチにおいて適正量を調整して装入することができるので、微粉炭吹込量が変化する高炉操業においても、高炉内の良好なガス流れおよび荷下がりを維持しながら、高結晶水含有鉱石を安定して効果的に使用できる。したがって、本発明の鉱石装入方法は、微粉炭吹込量の変化するベルレス高炉において、炉内の通気性を確保し、安定操業のもとに多量の高結晶水含有鉱石を使用することにより銑鉄コストの低減を図ることのできる操業方法として広範に適用できる。 According to the ore charging method of the present invention, according to the amount of pulverized coal injected into the bell-less blast furnace, the charging amount of ore containing high crystal water can be adjusted and charged in each batch of ore. Therefore, even in blast furnace operation in which the amount of pulverized coal injection changes, the ore containing high crystal water can be stably and effectively used while maintaining a good gas flow and unloading in the blast furnace. Therefore, the ore charging method of the present invention is a bellless blast furnace in which the amount of pulverized coal injection changes, ensuring the air permeability in the furnace, and using a large amount of ore containing high crystal water under stable operation. It can be widely applied as an operation method that can reduce costs.
1:コークス層、 2:第1バッチ鉱石層、 3:第2バッチ鉱石層、
4:高結晶水含有鉱石
1: coke layer, 2: first batch ore layer, 3: second batch ore layer,
4: Ore containing high crystal water
Claims (2)
A≦−0.05×PCR+15 ・・・・(1)
B≦3 ・・・・・・・・・・(2)
ここで、Aは、鉱石第1バッチで装入する高結晶水含有鉱石量が全装入鉱石量に対して占める比率(質量%)、Bは、鉱石第2バッチで装入する高結晶水含有鉱石量が全装入鉱石量に対して占める比率(質量%)、そしてPCRは、高炉への微粉炭吹込量(kg/pt)を表す。なお、ptは、銑鉄1t(トン)を表す。 The ore is divided into two batches, the first batch is charged over the entire range in the radial direction of the furnace, and the ore charging method into the bell-less blast furnace in which the second batch is charged into the furnace wall portion, depending on the amount of pulverized coal injection. The charging ratios of the ore containing high crystallization water with a crystallization water content of 3.5% by mass or more charged in the first batch and the second batch are represented by the following formulas (1) and (2), respectively. A method for charging an ore containing high crystal water into a bell-less blast furnace, characterized by adjusting the relationship so as to satisfy the relationship.
A ≦ −0.05 × PCR + 15 (1)
B ≦ 3 (2)
Here, A is the ratio (% by mass) of the amount of ore containing high crystal water charged in the first batch of ore to the total amount of ore charged, and B is the high crystal water charged in the second batch of ore. The ratio (mass%) that the amount of containing ore occupies with respect to the amount of all ores charged, and PCR represent the amount of pulverized coal injected into the blast furnace (kg / pt). In addition, pt represents pig iron 1t (ton).
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