WO2023199550A1 - Operation method for blast furnace - Google Patents

Operation method for blast furnace Download PDF

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Publication number
WO2023199550A1
WO2023199550A1 PCT/JP2022/046305 JP2022046305W WO2023199550A1 WO 2023199550 A1 WO2023199550 A1 WO 2023199550A1 JP 2022046305 W JP2022046305 W JP 2022046305W WO 2023199550 A1 WO2023199550 A1 WO 2023199550A1
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gas
volume
blast furnace
furnace
raw material
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PCT/JP2022/046305
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French (fr)
Japanese (ja)
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直美 澤木
雄基 川尻
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Ｊｆｅスチール株式会社
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Priority to JP2023516075A priority Critical patent/JP7552881B2/en
Publication of WO2023199550A1 publication Critical patent/WO2023199550A1/en

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B5/00—Making pig-iron in the blast furnace

Definitions

  • the present invention relates to a method of operating a blast furnace that generates highly concentrated reducing gas in the blast furnace in front of the tuyere, and more specifically, improves the properties of slag in the cohesive zone and dripping zone in the blast furnace, and improves the air permeability in the blast furnace. Concerning improving blast furnace operating methods.
  • the coal-derived reducing agent ratio refers to the total mass of coal-derived coke and coal-derived reducing gas required to produce 1 ton of hot metal.
  • the reducing agent has the role of generating heat in the furnace to raise the temperature of the charge, and the role of reducing iron ore, iron ore sinter, and iron ore pellets, which are iron-based raw materials in the furnace.
  • the reducing agent ratio and reduce the amount of CO 2 gas discharged it is necessary to increase the reduction efficiency of the reducing agent while maintaining the amount of heat in the furnace.
  • Hydrogen is attracting attention as a reducing agent for the purpose of reducing CO 2 gas emissions.
  • the reduction of iron ore with hydrogen is an endothermic reaction, but the endothermic amount is smaller than the direct reduction reaction (reaction formula: FeO+C ⁇ Fe+CO), and the reduction rate with hydrogen is faster than the reduction rate with CO gas. Therefore, by blowing hydrogen-based gas into the blast furnace, it is possible to simultaneously reduce CO 2 gas emissions and improve reduction efficiency.
  • Blast furnaces produce pig iron and, at the same time, produce a large amount of blast furnace slag (an oxide composed of FeO, CaO, Al 2 O 3 , MgO, SiO 2 , etc.) as a byproduct.
  • blast furnace slag an oxide composed of FeO, CaO, Al 2 O 3 , MgO, SiO 2 , etc.
  • Patent Documents 1 to 3 have been proposed as conventional techniques for solving problems similar to the above problems.
  • Patent Document 1 discloses a blast furnace operation in which coke is charged from the top of the furnace and auxiliary fuel is injected from the tuyere.
  • the ratio of Al 2 O 3 and SiO 2 of coke and auxiliary fuel (Al 2 O 3 /SiO 2 ) is set to 0.6 or more, and the basicity of blast furnace slag ((CaO + Al 2 O 3 + MgO) /SiO 2 ) to 1.8 or more improves the properties of blast furnace slag and improves air permeability and liquid permeability.
  • Patent Document 2 discloses a blast furnace operating method in which pulverized coal of 150 kg or more per ton of tapped iron is blown into the blast furnace through the tuyere along with hot air. According to Patent Document 2, more than 80% of the charge excluding coke charged from the top of the furnace contains 4.0 to 4.8 mass % of SiO2 components and 1.2 to 2.4 mass % of MgO components. %, the CaO component is 6.0 to 9.0 mass %, and the Al 2 O 3 component is 1.9 to 2.5 mass %. It is said that the viscosity of slag can be kept low.
  • Patent Document 3 discloses that high strength ( SI >92%) and high reducibility (RI>70 %) of sintered ore is disclosed. According to Patent Document 3, by injecting an amount of auxiliary raw material from the blast furnace tuyere corresponding to the difference in the blending ratio of auxiliary raw materials between high-strength and highly reducible sintered ore and normally used sintered ore. The company claims that it will be able to operate at a high ore/reducing material ratio in a stable manner over the long term.
  • the concentration of reducing gas generated in the furnace before the tuyere is extremely high. Therefore, the reduction rate of the iron-based raw material increases and the FeO concentration in the slag decreases in the furnace, and the FeO component in the slag decreases to a range lower than the operating range described in the above-mentioned prior art.
  • the above-mentioned prior art does not consider the case where the FeO content in the slag further decreases.
  • the present invention was made in view of the above circumstances, and its purpose is to improve the slag properties and reduce the FeO component in the slag when operating a blast furnace that generates high concentration reducing gas in the furnace in front of the tuyere. It is an object of the present invention to provide a blast furnace operating method that can ensure air permeability in a cohesive zone and a dripping zone in a blast furnace even if the air permeability decreases.
  • the gist of the present invention for solving the above problems is as follows.
  • [1] A method of operating a blast furnace, in which iron-based raw materials, auxiliary raw materials, and coke are charged from the top of the blast furnace, and gas is injected from the tuyeres of the blast furnace to generate high-concentration reducing gas in the furnace before the tuyeres.
  • a method for operating a blast furnace wherein the basicity of the total raw material components of the iron-based raw material and the auxiliary raw material is within a predetermined range.
  • [2] The method for operating a blast furnace according to [1], wherein the basicity of the total ingredients of the raw materials is within a range of 1.0 or more and 1.7 or less.
  • the high concentration reducing gas is composed of H 2 gas, N 2 gas and CO gas when expressed as a Bosch gas composition, and the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas.
  • the high concentration reducing gas is composed of H 2 gas, N 2 gas and CO gas when expressed as a Bosch gas composition, and the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas.
  • the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas.
  • the basicity (mass% CaO/mass% SiO 2 ) of the total raw material components of iron-based raw materials and auxiliary raw materials is within the specified range.
  • the viscosity of the slag generated in the cohesive zone and dripping zone in the blast furnace is optimized, and the liquid permeability of the slag in the blast furnace is controlled within the operable range.As a result, the gas permeability in the blast furnace is improved. By keeping it in good condition, stable operation of the blast furnace can be realized.
  • FIG. 1 shows the composition of the high-concentration reducing gas produced in the furnace before the tuyere in the blast furnace operating method according to the present embodiment in the gas component composition of a ternary diagram of H 2 gas-N 2 gas-CO gas. It is a figure showing a range as a Bosch gas composition.
  • FIG. 2 is a graph showing the influence of the basicity of the total raw material components on the amount of melt dripping in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere.
  • FIG. 3 is a graph showing the influence of the basicity of the total raw material components on the ventilation resistance index KS in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere.
  • the operating method of the blast furnace is to charge iron-based raw materials, auxiliary raw materials, and coke into the blast furnace alternately and in layers from the top of the blast furnace, and to charge the iron-based raw materials, auxiliary raw materials, and coke into the blast furnace from the tuyere provided at the bottom of the blast furnace.
  • This is a blast furnace operating method in which gas is blown into the blast furnace and the gas blown through the tuyeres generates highly concentrated reducing gas in the blast furnace in front of the tuyeres.
  • Iron-based raw materials include, for example, iron ore, sintered iron ore, iron ore pellets, reduced iron, and iron scrap.
  • the auxiliary raw materials include SiO 2 and CaO singly or in combination.
  • the types of iron-based raw materials, auxiliary raw materials, and coke to be used are not particularly limited, and any iron-based raw materials, auxiliary raw materials, and coke used in conventional blast furnace operations can be suitably used in the present invention.
  • the gas for generating the high concentration reducing gas contains a reducing component that reduces iron-based raw materials in the blast furnace.
  • the reducing components that reduce iron-based raw materials in the blast furnace include not only CO gas, H2 gas, and hydrocarbon gas, which are components that can reduce iron-based raw materials, but also reduction through reaction with coke or decomposition reaction. It also includes CO 2 gas, H 2 O gas, etc., which are components that generate gas.
  • FIG. 1 shows the composition of the high-concentration reducing gas produced in the furnace before the tuyere in the blast furnace operating method according to the present embodiment in the gas component composition of a ternary diagram of H 2 gas-N 2 gas-CO gas. It is a figure showing a range as a Bosch gas composition.
  • the high-concentration reducing gas in this embodiment is a reducing gas whose average reduction rate is 80% or more when iron-based raw materials are reduced at 900° C. for 180 minutes using the high-concentration reducing gas.
  • Region A is the point O (H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %), point P in the ternary system diagram of H 2 gas - N 2 gas - CO gas. ( H2 gas; 100 volume%, N2 gas; 0 volume%, CO gas; 0 volume%), point Q ( H2 gas; 29 volume%, N2 gas; 71 volume%, CO gas; 0 volume% ) and point R (H 2 gas; 0 volume %, N 2 gas; 37 volume %, CO gas; 63 volume %). Further, FIG. 1 shows a comparison of gas compositions in conventional general blast furnace operating ranges.
  • the present inventors conducted a test to generate high concentration reducing gas in the furnace in front of the tuyere using a small test furnace with a scale of 1/4 that simulates a blast furnace.
  • the slag components were investigated.
  • Table 1 shows an example of the composition of the iron-based raw materials used in the small test reactor.
  • the ferrous raw materials, auxiliary raw materials, and coke were mixed in the same manner as in the operating method described in Patent Document 2, such that the basicity of the total raw material component of the ferrous raw materials and auxiliary raw materials was 2.0.
  • the CaO component was calculated to be 9.2% by mass, the CaO component was calculated to be 52.5 to 56.7% by mass, and the MgO component was calculated to be 5.3 to 7.3% by mass.
  • the basicity of the slag increased to approximately 2.0, and the amount of slag dripped decreased to about one-tenth of that in conventional tests, which deteriorated the gas permeability to a point outside the range where the test could be continued stably. .
  • the amount of melt dropped was determined by collecting the melt dropped during the test after the experiment and measuring its total weight using a weighing scale.
  • the ventilation resistance index KS is the ventilation resistance K value (1/m) calculated based on the pressure loss measured in the area where the temperature inside the furnace is 1000°C or higher and the physical property values estimated from the operating conditions. Calculated as an integral value.
  • the ventilation resistance K value (1/m) is calculated using the following equation (1).
  • K ( ⁇ P/H)/( ⁇ gas 0.7 ⁇ gas 0.3 ⁇ v gas 1.7 )...(1)
  • ⁇ P is the pressure loss (Pa)
  • H is the thickness of the packed bed in the furnace (m)
  • ⁇ gas is the gas density (kg/m 3 )
  • ⁇ gas is the gas viscosity (Pa ⁇ s )
  • v gas is the gas flow velocity (m/s).
  • ⁇ P is obtained by installing pressure gauges on the tuyere and the furnace wall in the upper part of the test furnace (in the space above the packed bed) and calculating the difference in pressure.
  • H is measured by inserting a measuring jig into a hole drilled in the upper part of the test furnace to measure the position of the surface of the packed bed, and then calculating the distance in the height direction between the surface position of the packed bed and the position where the tuyeres are installed.
  • the position of the filled layer surface may be measured using a laser distance meter.
  • ⁇ gas can be calculated from the gas component introduced from the tuyere, the temperature inside the furnace, and the pressure inside the furnace.
  • ⁇ gas can be calculated from the gas components introduced from the tuyere and the temperature inside the furnace.
  • v gas can be calculated from the gas flow rate introduced from the tuyere, the temperature inside the furnace, and the pressure inside the furnace.
  • thermometers are installed on the furnace wall at positions corresponding to the packed bed, and the average value of the measured values of the thermometers is used.
  • pressure inside the furnace a plurality of thermometers are installed on the furnace wall at positions corresponding to the packed bed, and the average value of the measured values of the pressure gauges is used.
  • the average value of the pressure at the tuyere used to calculate ⁇ P and the pressure at the top of the packed bed may be used as the pressure in the furnace.
  • the ventilation resistance index KS is calculated using the following formula (2).
  • Tmax is the maximum temperature at which the pressure loss in the furnace was measured, and is approximately 1500 to 1650°C, although it varies depending on the measurement.
  • FIG. 2 is a graph showing the influence of the basicity of the total raw material components on the amount of melt dripping in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere.
  • the horizontal axis of FIG. 2 is the basicity of the total raw material components (mass % CaO/mass % SiO 2 ), and the vertical axis is the melt dropping amount (g).
  • FIG. 3 is a graph showing the influence of the basicity of the total raw material components on the ventilation resistance index KS in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere.
  • the horizontal axis of FIG. 3 is the basicity of the total raw material components (mass% CaO/mass% SiO 2 ), and the vertical axis is the ventilation resistance index KS (10 5 °C/m).
  • the amount of melt dropped increased when the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials was within the range of 1.0 to 1.7.
  • the ventilation resistance index KS decreases to the target value of 2000 or less. This was confirmed.
  • the target value of 2000 for the ventilation resistance index KS is a threshold value at which stable testing can be continued.
  • a stable test means a test in which the surface height of the packed bed decreases uniformly over time and no problems such as blow-through occur.
  • the operating method of the blast furnace according to the present embodiment was made based on the above test results, and consists of charging iron-based raw materials, auxiliary raw materials, and coke from the top of the blast furnace, and charging the iron-based raw materials, auxiliary raw materials, and coke from the tuyere of the blast furnace to the furnace in front of the tuyere.
  • a method of operating a blast furnace in which a gas that generates high concentration reducing gas is injected into the blast furnace the method of operating a blast furnace in which the basicity of the total raw material components of the iron-based raw materials to be charged and the auxiliary raw materials to be charged is within a predetermined range. be.
  • the basicity of the total raw material components of the iron-based raw material to be charged and the auxiliary raw materials to be charged is preferably within the range of 1.0 or more and 1.7 or less. Thereby, the dripping property and air permeability of the melt in the lower part of the blast furnace can be improved.
  • the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials is less than 1.0, and when the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials is more than 1.7, both slag This is not preferable because the viscosity of the liquid increases and goes out of the stable operation range.
  • the basicity of the total raw material components of the iron-based raw materials and auxiliary raw materials to be charged is more preferably 1.1 or more and 1.7 or less, and even more preferably 1.4 or more and 1.5 or less. This further reduces the viscosity of the slag and further improves the dripping properties and air permeability of the melt.
  • the amount of H 2 gas (including hydrogen in hydrocarbons) in the high concentration reducing gas is within the range of 0 to 500 Nm 3 /ton of hot metal. Thereby, it is possible to suppress a decrease in the temperature inside the furnace and a decrease in the reduction reaction rate. On the other hand, if the amount of H 2 gas in the high-concentration reducing gas exceeds 500 Nm 3 /ton of hot metal, the furnace temperature will drop and the reduction reaction rate will decrease, which is not preferable. Further, when blowing H 2 gas alone, it is preferable to heat the H 2 gas before blowing in order to maintain the temperature before the tuyere within the operating range.
  • the iron-based raw material to be charged and the auxiliary raw material to be charged are The basicity of the total raw material components is controlled within a predetermined range.
  • the viscosity of the slag generated in the cohesive zone and dripping zone in the blast furnace is optimized, and the liquid permeability of the slag in the blast furnace is controlled within the operational range, resulting in good gas permeability in the blast furnace. This allows stable operation to be achieved.

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Abstract

Provided is an operation method for a blast furnace that, when the blast furnace is operated to generate a high-concentration reducing gas within the furnace before a tuyere, improves the properties of slag produced in a lower part of the furnace, even if the amount of FeO in the slag decreases, and that can ensure ventilation in a cohesive zone and a dripping zone within the furnace.　This operation method for a blast furnace includes loading an iron-based raw material, an auxiliary raw material, and coke through a throat of the blast furnace, and blowing in, from a tuyere of the blast furnace, a gas that generates a high-concentration reducing gas within the furnace before the tuyere, wherein the basicity of all raw material constituents of the iron-based raw material and the auxiliary raw material is within a prescribed range. At this time, It is preferable for the basicity of all raw material constituents to be within the range 1.0–1.7.

Description

高炉の操業方法How to operate a blast furnace
　本発明は、羽口前の高炉内で高濃度還元ガスを発生させる高炉の操業方法に関し、詳しくは、高炉内の融着帯及び滴下帯におけるスラグの性状を改善し、高炉内の通気性を向上させる高炉の操業方法に関する。 The present invention relates to a method of operating a blast furnace that generates highly concentrated reducing gas in the blast furnace in front of the tuyere, and more specifically, improves the properties of slag in the cohesive zone and dripping zone in the blast furnace, and improves the air permeability in the blast furnace. Concerning improving blast furnace operating methods.
　近年、温室効果ガスの一つであるＣＯ２ガス（二酸化炭素ガス）の排出量削減の動きが高まっている。高炉による製鉄法では、還元材として炭材を使用するため、多量のＣＯ２ガスが発生する。したがって、鉄鋼業はＣＯ２ガスの排出量において主要な産業のひとつとなっており、ＣＯ２ガスの排出量削減という社会的要請に応えねばならない。具体的には、高炉操業での更なる石炭由来の還元材比の削減が急務となっている。石炭由来の還元材比とは、溶銑１トンを製造するために要した石炭由来のコークス及び石炭由来の還元ガスの合計質量をいう。 In recent years, there has been a growing movement to reduce emissions of CO2 gas (carbon dioxide gas), which is one of the greenhouse gases. In the iron manufacturing method using a blast furnace, a large amount of CO 2 gas is generated because carbonaceous material is used as a reducing agent. Therefore, the steel industry is one of the major industries in terms of CO 2 gas emissions, and must respond to the social demand for reducing CO 2 gas emissions. Specifically, there is an urgent need to further reduce the ratio of coal-derived reducing agents in blast furnace operations. The coal-derived reducing agent ratio refers to the total mass of coal-derived coke and coal-derived reducing gas required to produce 1 ton of hot metal.
　還元材は、炉内で熱となって装入物を昇温させる役割と、炉内の鉄系原料である鉄鉱石、鉄鉱石の焼結鉱、鉄鉱石のペレットを還元する役割がある。還元材比を低減させてＣＯ２ガスの排出量を削減するには、炉内の熱量を保ちながら、還元材の還元効率を高める必要がある。 The reducing agent has the role of generating heat in the furnace to raise the temperature of the charge, and the role of reducing iron ore, iron ore sinter, and iron ore pellets, which are iron-based raw materials in the furnace. In order to reduce the reducing agent ratio and reduce the amount of CO 2 gas discharged, it is necessary to increase the reduction efficiency of the reducing agent while maintaining the amount of heat in the furnace.
　ＣＯ２ガスの排出量削減を目的とした還元材として、水素が注目されている。水素による鉄鉱石の還元は吸熱反応であるが、その吸熱量は直接還元反応（反応式：ＦｅＯ＋Ｃ→Ｆｅ＋ＣＯ）よりも小さく、水素による還元速度はＣＯガスによる還元速度よりも速い。このため、高炉への水素系ガスの吹き込みにより、ＣＯ２ガスの排出量削減、及び、還元効率の向上を同時に図ることができる。 Hydrogen is attracting attention as a reducing agent for the purpose of reducing CO 2 gas emissions. The reduction of iron ore with hydrogen is an endothermic reaction, but the endothermic amount is smaller than the direct reduction reaction (reaction formula: FeO+C→Fe+CO), and the reduction rate with hydrogen is faster than the reduction rate with CO gas. Therefore, by blowing hydrogen-based gas into the blast furnace, it is possible to simultaneously reduce CO 2 gas emissions and improve reduction efficiency.
　高炉の安定操業のためには、高炉内の鉄系原料が融着している融着帯の通気性を確保することが必要である。しかしながら、羽口前の炉内で高濃度還元ガスを発生させる高炉操業、及び、従来の操業よりも炉内還元ガス濃度が高くて還元反応速度が速い高炉操業においては、高炉内の通気性が明らかになっていない。 For the stable operation of a blast furnace, it is necessary to ensure the permeability of the cohesive zone where the iron-based raw materials in the blast furnace are fused. However, in blast furnace operations in which highly concentrated reducing gas is generated in the furnace in front of the tuyeres, and in blast furnace operations in which the reducing gas concentration in the furnace is higher and the reduction reaction rate is faster than in conventional operations, the ventilation inside the blast furnace is It's not clear.
　高炉は、銑鉄を生産すると同時に、副産物である高炉スラグ（ＦｅＯ、ＣａＯ、Ａｌ２Ｏ３、ＭｇＯ、及びＳｉＯ２などで構成される酸化物）を多量に産出する。炉内の通気性を良好に保つには、産出される高炉スラグの粘度を低く抑え、通液性を確保できる原料設計をすることが必要である。 Blast furnaces produce pig iron and, at the same time, produce a large amount of blast furnace slag (an oxide composed of FeO, CaO, Al 2 O 3 , MgO, SiO 2 , etc.) as a byproduct. In order to maintain good air permeability inside the furnace, it is necessary to keep the viscosity of the produced blast furnace slag low and to design raw materials that can ensure liquid permeability.
　上記課題に類似した問題を解決するための従来技術として、特許文献１～３に開示される技術が提案されている。 Technologies disclosed in Patent Documents 1 to 3 have been proposed as conventional techniques for solving problems similar to the above problems.
　特許文献１には、炉頂からコークスを装入し、羽口から補助燃料を吹き込む高炉操業が開示されている。特許文献１によると、コークス及び補助燃料のＡｌ２Ｏ３とＳｉＯ２との比（Ａｌ２Ｏ３／ＳｉＯ２）を０．６以上とし、高炉スラグの塩基度（（ＣａＯ＋Ａｌ２Ｏ３＋ＭｇＯ）／ＳｉＯ２）を１．８以上とすることで、高炉スラグの性状が改善し、通気性及び通液性を向上できるとしている。 Patent Document 1 discloses a blast furnace operation in which coke is charged from the top of the furnace and auxiliary fuel is injected from the tuyere. According to Patent Document 1, the ratio of Al 2 O 3 and SiO 2 of coke and auxiliary fuel (Al 2 O 3 /SiO 2 ) is set to 0.6 or more, and the basicity of blast furnace slag ((CaO + Al 2 O 3 + MgO) /SiO 2 ) to 1.8 or more improves the properties of blast furnace slag and improves air permeability and liquid permeability.
　特許文献２には、出銑１トン当り１５０ｋｇ以上の微粉炭を羽口から熱風とともに高炉内に吹き込む高炉操業法が開示されている。特許文献２によると、炉頂から装入されるコークスを除く装入物の８０％以上に、ＳｉＯ２成分が４．０～４．８質量％、ＭｇＯ成分が１．２～２．４質量％、ＣａＯ成分が６．０～９．０質量％、Ａｌ２Ｏ３成分が１．９～２．５質量％の焼結鉱を用いることで、スラグ組成のＦｅＯ成分が低下しても滴下スラグの粘度を低く抑えられるとしている。 Patent Document 2 discloses a blast furnace operating method in which pulverized coal of 150 kg or more per ton of tapped iron is blown into the blast furnace through the tuyere along with hot air. According to Patent Document 2, more than 80% of the charge excluding coke charged from the top of the furnace contains 4.0 to 4.8 mass % of SiO2 components and 1.2 to 2.4 mass % of MgO components. %, the CaO component is 6.0 to 9.0 mass %, and the Al 2 O 3 component is 1.9 to 2.5 mass %. It is said that the viscosity of slag can be kept low.
　特許文献３には、通常使用される焼結鉱中のＡｌ２Ｏ３量に応じて、副原料の配合比率を調整して高強度（ＳＩ＞９２％）且つ高被還元性（ＲＩ＞７０％）の焼結鉱を用いる高炉操業方法が開示されている。特許文献３によると、高強度且つ高被還元性の焼結鉱と、通常使用される焼結鉱との副原料の配合比率の差に相当する量の副原料を高炉羽口から吹き込むことで、長期的に安定して高鉱石／還元材比操業を行えるとしている。 Patent Document 3 discloses that high strength ( SI >92%) and high reducibility (RI>70 %) of sintered ore is disclosed. According to Patent Document 3, by injecting an amount of auxiliary raw material from the blast furnace tuyere corresponding to the difference in the blending ratio of auxiliary raw materials between high-strength and highly reducible sintered ore and normally used sintered ore. The company claims that it will be able to operate at a high ore/reducing material ratio in a stable manner over the long term.
特開２００４－１０９４８号公報Japanese Patent Application Publication No. 2004-10948 特開平９－１３１０７号公報Japanese Patent Application Publication No. 9-13107 特開２００５－２９８９２３号公報Japanese Patent Application Publication No. 2005-298923
　しかしながら、これら従来技術は、何れも、羽口からＳｉＯ２粉末などの副原料、ＣａＯやＳｉＯ２などを含む補助燃料または微粉炭を吹き込む高炉操業を対象としており、羽口前の炉内で高濃度還元ガスを発生させる高炉操業における装入原料成分やスラグ成分については言及していない。 However, all of these conventional technologies target blast furnace operation in which auxiliary raw materials such as SiO 2 powder, auxiliary fuel containing CaO, SiO 2 , etc., or pulverized coal are injected through the tuyere, and the blast furnace is There is no mention of charging raw material components or slag components in blast furnace operations that generate concentrated reducing gas.
　本発明における高炉操業では羽口前の炉内で生成される還元ガスの濃度が非常に高い。このため、炉内で鉄系原料の還元率の上昇及びスラグ中ＦｅＯ濃度の減少が起こり、スラグ中ＦｅＯ成分が上記の従来技術に記載される操業範囲よりも低い範囲まで低下する。上記の従来技術は、スラグ中ＦｅＯ成分が更に低下した場合について考慮していない。 In the blast furnace operation of the present invention, the concentration of reducing gas generated in the furnace before the tuyere is extremely high. Therefore, the reduction rate of the iron-based raw material increases and the FeO concentration in the slag decreases in the furnace, and the FeO component in the slag decreases to a range lower than the operating range described in the above-mentioned prior art. The above-mentioned prior art does not consider the case where the FeO content in the slag further decreases.
　つまり、羽口前の炉内で発生する高濃度還元ガスが、図１（図１の説明は後述する）の領域Ａの範囲内（Ｈ２ガス＝０～１００体積％、Ｎ２ガス＝０～７１体積％、ＣＯガス＝０～１００体積％を含む範囲内）となるように操業した場合、従来の操業以上に、鉄系原料の低温からの還元が促進され、炉下部における鉄系原料の到達還元率が上昇する。この場合、従来の操業方法のままでは、スラグ中ＦｅＯ成分の減少によりスラグ通液性が低下し、スラグがコークス層の空隙中に滞留し、炉内通気抵抗が増加して吹き抜けが誘発されることが懸念される。 In other words, the highly concentrated reducing gas generated in the furnace in front of the tuyere is within the range of area A in Figure 1 (the explanation of Figure 1 will be given later) (H 2 gas = 0 to 100% by volume, N 2 gas = 0). -71% by volume, CO gas = 0 to 100% by volume), the reduction of the ferrous raw material from low temperature is promoted more than in conventional operation, and the reduction of the ferrous raw material in the lower part of the furnace is accelerated. The return rate achieved will increase. In this case, if the conventional operating method is continued, the FeO component in the slag decreases, causing the slag's liquid permeability to decrease, causing the slag to remain in the voids of the coke layer, increasing the ventilation resistance in the furnace, and causing blow-by. This is a concern.
　本発明は上記事情を鑑みてなされたもので、その目的は、羽口前の炉内で高濃度還元ガスを発生させる高炉操業を実施するに際し、スラグ性状を改善してスラグ中のＦｅＯ成分が減少しても高炉内の融着帯及び滴下帯における通気性を確保できる、高炉の操業方法を提供することである。 The present invention was made in view of the above circumstances, and its purpose is to improve the slag properties and reduce the FeO component in the slag when operating a blast furnace that generates high concentration reducing gas in the furnace in front of the tuyere. It is an object of the present invention to provide a blast furnace operating method that can ensure air permeability in a cohesive zone and a dripping zone in a blast furnace even if the air permeability decreases.
　上記課題を解決するための本発明の要旨は以下のとおりである。
［１］　高炉の炉頂から鉄系原料、副原料及びコークスを装入し、高炉の羽口から羽口前の炉内で高濃度還元ガスを発生させるガスを吹き込む高炉の操業方法であって、前記鉄系原料と前記副原料との原料総成分の塩基度を所定範囲内にする、高炉の操業方法。
［２］　前記原料総成分の塩基度を１．０以上１．７以下の範囲内にする、［１］に記載の高炉の操業方法。
［３］　前記高濃度還元ガスは、ボッシュガス組成として表すと、Ｈ２ガス、Ｎ２ガス及びＣＯガスで構成され、Ｈ２ガス、Ｎ２ガス及びＣＯガスの割合が、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムにおけるＨ２ガス；０体積％、Ｎ２ガス；０体積％、ＣＯガス；１００体積％の点と、Ｈ２ガス；１００体積％、Ｎ２ガス；０体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；２９体積％、Ｎ２ガス；７１体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；０体積％、Ｎ２ガス；３７体積％、ＣＯガス；６３体積％の点との４点で囲まれる領域内の組成であり、０～１００体積％の範囲内のＨ２ガスと、０～７１体積％の範囲内のＮ２ガスと、０～１００体積％の範囲内のＣＯガスとを含む、［１］に記載の高炉の操業方法。
［４］　前記高濃度還元ガスは、ボッシュガス組成として表すと、Ｈ２ガス、Ｎ２ガス及びＣＯガスで構成され、Ｈ２ガス、Ｎ２ガス及びＣＯガスの割合が、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムにおけるＨ２ガス；０体積％、Ｎ２ガス；０体積％、ＣＯガス；１００体積％の点と、Ｈ２ガス；１００体積％、Ｎ２ガス；０体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；２９体積％、Ｎ２ガス；７１体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；０体積％、Ｎ２ガス；３７体積％、ＣＯガス；６３体積％の点との４点で囲まれる領域内の組成であり、０～１００体積％の範囲内のＨ２ガスと、０～７１体積％の範囲内のＮ２ガスと、０～１００体積％の範囲内のＣＯガスとを含む、［２］に記載の高炉の操業方法。
［５］　前記高濃度還元ガス中のＨ２ガス量は０～５００Ｎｍ３／溶銑－ｔｏｎの範囲内である、［１］から［４］のいずれかに記載の高炉の操業方法。 The gist of the present invention for solving the above problems is as follows.
[1] A method of operating a blast furnace, in which iron-based raw materials, auxiliary raw materials, and coke are charged from the top of the blast furnace, and gas is injected from the tuyeres of the blast furnace to generate high-concentration reducing gas in the furnace before the tuyeres. , A method for operating a blast furnace, wherein the basicity of the total raw material components of the iron-based raw material and the auxiliary raw material is within a predetermined range.
[2] The method for operating a blast furnace according to [1], wherein the basicity of the total ingredients of the raw materials is within a range of 1.0 or more and 1.7 or less.
[3] The high concentration reducing gas is composed of H 2 gas, N 2 gas and CO gas when expressed as a Bosch gas composition, and the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas. In the ternary system diagram of 2 gases - CO gas, the points at H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %, and H 2 gas; 100 volume %, N 2 gas; 0 Volume %, CO gas; 0 volume % point, H 2 gas; 29 volume %, N 2 gas; 71 volume %, CO gas; 0 volume % point, H 2 gas; 0 volume %, N 2 gas ; 37 volume %, CO gas; 63 volume % point and the composition within the area surrounded by the four points, H 2 gas within the range of 0 to 100 volume % and 0 to 71 volume % The method for operating a blast furnace according to [1], comprising N 2 gas and CO gas in a range of 0 to 100% by volume.
[4] The high concentration reducing gas is composed of H 2 gas, N 2 gas and CO gas when expressed as a Bosch gas composition, and the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas. In the ternary system diagram of 2 gases - CO gas, H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %, and H 2 gas; 100 volume %, N 2 gas; 0. Volume %, CO gas; 0 volume % point, H 2 gas; 29 volume %, N 2 gas; 71 volume %, CO gas; 0 volume % point, H 2 gas; 0 volume %, N 2 gas ; 37 volume %, CO gas; composition within the area surrounded by the four points with the 63 volume % point, H 2 gas within the range of 0 to 100 volume %, and CO gas within the range of 0 to 71 volume %. The method for operating a blast furnace according to [2], comprising N 2 gas and CO gas in a range of 0 to 100% by volume.
[5] The method for operating a blast furnace according to any one of [1] to [4], wherein the amount of H 2 gas in the high concentration reducing gas is within a range of 0 to 500 Nm 3 /ton of hot metal.
　本発明では、羽口前の炉内で高濃度還元ガスを発生させる高炉操業を実施するに際し、鉄系原料と副原料との原料総成分の塩基度（質量％ＣａＯ／質量％ＳｉＯ２）を所定範囲内にする。これにより、高炉内の融着帯及び滴下帯で生成するスラグの粘度が最適化され、高炉内でのスラグの通液性が操業可能範囲に制御され、その結果、高炉内のガス通気性を良好に保ち、高炉の安定操業を実現できる。 In the present invention, when carrying out blast furnace operation in which highly concentrated reducing gas is generated in the furnace in front of the tuyere, the basicity (mass% CaO/mass% SiO 2 ) of the total raw material components of iron-based raw materials and auxiliary raw materials is within the specified range. As a result, the viscosity of the slag generated in the cohesive zone and dripping zone in the blast furnace is optimized, and the liquid permeability of the slag in the blast furnace is controlled within the operable range.As a result, the gas permeability in the blast furnace is improved. By keeping it in good condition, stable operation of the blast furnace can be realized.
図１は、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムのガス成分組成において、本実施形態に係る高炉の操業方法で羽口前の炉内で生成させる高濃度還元ガスの成分範囲をボッシュガス組成として示す図である。FIG. 1 shows the composition of the high-concentration reducing gas produced in the furnace before the tuyere in the blast furnace operating method according to the present embodiment in the gas component composition of a ternary diagram of H 2 gas-N 2 gas-CO gas. It is a figure showing a range as a Bosch gas composition. 図２は、羽口前の炉内で高濃度還元ガスを生成させる試験において、溶融物滴下量に及ぼす原料総成分の塩基度の影響を示すグラフである。FIG. 2 is a graph showing the influence of the basicity of the total raw material components on the amount of melt dripping in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere. 図３は、羽口前の炉内で高濃度還元ガスを生成させる試験において、通気抵抗指数ＫＳに及ぼす原料総成分の塩基度の影響を示すグラフである。FIG. 3 is a graph showing the influence of the basicity of the total raw material components on the ventilation resistance index KS in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere.
　以下、本発明の実施形態を説明する。本実施形態に係る高炉の操業方法は、高炉の炉頂から鉄系原料、副原料及びコークスを高炉内に交互に且つ層状に装入するとともに、高炉の下部に設けられた羽口から高炉内にガスを吹き込み、羽口から吹き込んだガスにより、羽口前の高炉内で高濃度還元ガスを生成させる高炉操業方法である。鉄系原料には、例えば、鉄鉱石、鉄鉱石の焼結鉱、鉄鉱石のペレット、還元鉄及び鉄スクラップが含まれる。副原料には、ＳｉＯ２、ＣａＯが単独または複合して含まれる。使用する鉄系原料、副原料及びコークスの種類は特に制限されず、従来の高炉操業に使用される鉄系原料、副原料及びコークスであれば本発明においても好適に使用できる。 Embodiments of the present invention will be described below. The operating method of the blast furnace according to this embodiment is to charge iron-based raw materials, auxiliary raw materials, and coke into the blast furnace alternately and in layers from the top of the blast furnace, and to charge the iron-based raw materials, auxiliary raw materials, and coke into the blast furnace from the tuyere provided at the bottom of the blast furnace. This is a blast furnace operating method in which gas is blown into the blast furnace and the gas blown through the tuyeres generates highly concentrated reducing gas in the blast furnace in front of the tuyeres. Iron-based raw materials include, for example, iron ore, sintered iron ore, iron ore pellets, reduced iron, and iron scrap. The auxiliary raw materials include SiO 2 and CaO singly or in combination. The types of iron-based raw materials, auxiliary raw materials, and coke to be used are not particularly limited, and any iron-based raw materials, auxiliary raw materials, and coke used in conventional blast furnace operations can be suitably used in the present invention.
　高濃度還元ガスを生成させるためのガスは、高炉内の鉄系原料を還元する還元成分を含む。ここで、高炉内の鉄系原料を還元する還元成分には、鉄系原料を還元できる成分であるＣＯガス、Ｈ２ガス、炭化水素ガスだけでなく、コークスとの反応または分解反応などによって還元ガスを生成する成分であるＣＯ２ガス、Ｈ２Ｏガスなども含まれる。 The gas for generating the high concentration reducing gas contains a reducing component that reduces iron-based raw materials in the blast furnace. Here, the reducing components that reduce iron-based raw materials in the blast furnace include not only CO gas, H2 gas, and hydrocarbon gas, which are components that can reduce iron-based raw materials, but also reduction through reaction with coke or decomposition reaction. It also includes CO 2 gas, H 2 O gas, etc., which are components that generate gas.
　図１は、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムのガス成分組成において、本実施形態に係る高炉の操業方法で羽口前の炉内で生成させる高濃度還元ガスの成分範囲をボッシュガス組成として示す図である。本実施形態における高濃度還元ガスとは、当該高濃度還元ガスを用いて鉄系原料を９００℃で１８０分間還元した際の平均還元率が８０％以上になる還元ガスである。この還元ガスをボッシュガス組成で表すと、Ｈ２ガス、Ｎ２ガス及びＣＯガスで構成され、Ｈ２ガス、Ｎ２ガス及びＣＯガスの割合（但し、Ｈ２ガス＋Ｎ２ガス＋ＣＯガス＝１００体積％としたときの割合）が、図１に斜線部で示す領域Ａ（本発明の操業の範囲）の範囲内であり、０～１００体積％の範囲内のＨ２ガス、０～７１体積％の範囲内のＮ２ガス、０～１００体積％の範囲内のＣＯガスを含むガス組成である。 FIG. 1 shows the composition of the high-concentration reducing gas produced in the furnace before the tuyere in the blast furnace operating method according to the present embodiment in the gas component composition of a ternary diagram of H 2 gas-N 2 gas-CO gas. It is a figure showing a range as a Bosch gas composition. The high-concentration reducing gas in this embodiment is a reducing gas whose average reduction rate is 80% or more when iron-based raw materials are reduced at 900° C. for 180 minutes using the high-concentration reducing gas. Expressing this reducing gas in terms of Bosch gas composition, it is composed of H 2 gas, N 2 gas and CO gas, and the proportion of H 2 gas, N 2 gas and CO gas (however, H 2 gas + N 2 gas + CO gas = 100 H 2 gas (expressed as volume %) is within the shaded area A (range of operation of the present invention) shown in FIG. % of N 2 gas and CO gas within the range of 0 to 100% by volume.
　領域Ａは、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムにおいて、点Ｏ（Ｈ２ガス；０体積％、Ｎ２ガス；０体積％、ＣＯガス；１００体積％）、点Ｐ（Ｈ２ガス；１００体積％、Ｎ２ガス；０体積％、ＣＯガス；０体積％）、点Ｑ（Ｈ２ガス；２９体積％、Ｎ２ガス；７１体積％、ＣＯガス；０体積％）及び点Ｒ（Ｈ２ガス；０体積％、Ｎ２ガス；３７体積％、ＣＯガス；６３体積％）の４点で囲まれる範囲内である。また、図１には、従来の一般的な高炉操業範囲のガス組成を比較して示す。この領域Ａのうち、点Ｏ（Ｈ２ガス；０体積％、Ｎ２ガス；０体積％、ＣＯガス；１００体積％）、点Ｐ（Ｈ２ガス；１００体積％、Ｎ２ガス；０体積％、ＣＯガス；０体積％）、点Ｑ’（Ｈ２ガス；４３体積％、Ｎ２ガス；５７体積％、ＣＯガス；０体積％）及び点Ｒ’（Ｈ２ガス；０体積％、Ｎ２ガス；１４体積％、ＣＯガス；８６体積％）の４点で囲まれる範囲内は、鉄系原料を９００℃で１８０分間還元した際の平均還元率が９０％以上になるので、炉内の融着帯におけるスラグ成分中のＦｅＯ含有量が著しく低下する。このため、この成分範囲の高濃度還元ガスを羽口の炉内で生成させる場合には、スラグを含む溶融物の滴下量回復に向けた原料総成分の塩基度（質量％ＣａＯ／質量％ＳｉＯ２）の調整による効果がさらに高くなる。 Region A is the point O (H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %), point P in the ternary system diagram of H 2 gas - N 2 gas - CO gas. ( H2 gas; 100 volume%, N2 gas; 0 volume%, CO gas; 0 volume%), point Q ( H2 gas; 29 volume%, N2 gas; 71 volume%, CO gas; 0 volume% ) and point R (H 2 gas; 0 volume %, N 2 gas; 37 volume %, CO gas; 63 volume %). Further, FIG. 1 shows a comparison of gas compositions in conventional general blast furnace operating ranges. In this area A, point O (H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %), point P (H 2 gas; 100 volume %, N 2 gas; 0 volume %, CO gas; 0 volume %), point Q' (H 2 gas; 43 volume %, N 2 gas; 57 volume %, CO gas; 0 volume %) and point R' (H 2 gas; 0 volume %, Within the range surrounded by the four points ( N2 gas: 14 volume%, CO gas: 86 volume%), the average reduction rate when iron-based raw materials are reduced at 900°C for 180 minutes is 90% or more, so the furnace The FeO content in the slag components in the cohesive zone within the slag is significantly reduced. Therefore, when a highly concentrated reducing gas in this component range is generated in the tuyere furnace, the basicity of the total raw material components (mass%CaO/mass%SiO The effect of adjustment 2 ) becomes even higher.
　本発明者らは、高炉を模擬した縮尺１／４の小型試験炉を用い、羽口前の炉内で高濃度還元ガスを生成させる試験を行い、炉内の融着帯及び滴下帯でのスラグ成分の調査を行った。表１に、小型試験炉で使用した鉄系原料の成分組成の一例を示す。 The present inventors conducted a test to generate high concentration reducing gas in the furnace in front of the tuyere using a small test furnace with a scale of 1/4 that simulates a blast furnace. The slag components were investigated. Table 1 shows an example of the composition of the iron-based raw materials used in the small test reactor.
Figure JPOXMLDOC01-appb-T000001
  
Figure JPOXMLDOC01-appb-T000001
  
　小型試験炉において、鉄系原料、副原料及びコークスの配合を特許文献２に記載された操業方法と同じく、鉄系原料と副原料との原料総成分の塩基度が２．０である配合にして、羽口前の炉内で高濃度還元ガスを生成させる試験を行った。この試験条件では、炉内の融着帯におけるスラグ成分は、ＦｅＯ成分が３．５質量％未満、ＳｉＯ２成分が２５．４～２８．３質量％、Ａｌ２Ｏ３成分が８．６～９．２質量％、ＣａＯ成分が５２．５～５６．７質量％、ＭｇＯ成分が５．３～７．３質量％と算出された。スラグの塩基度が約２．０と高くなり、スラグの滴下量が従来の試験の１０分の１程度まで減少したことにより、ガス通気性が安定して試験が継続可能な範囲外まで悪化した。 In a small test reactor, the ferrous raw materials, auxiliary raw materials, and coke were mixed in the same manner as in the operating method described in Patent Document 2, such that the basicity of the total raw material component of the ferrous raw materials and auxiliary raw materials was 2.0. We conducted a test in which highly concentrated reducing gas was generated in the furnace in front of the tuyere. Under these test conditions, the slag components in the cohesive zone in the furnace include less than 3.5 mass% FeO component, 25.4 to 28.3 mass% SiO 2 component, and 8.6 to 8.6 mass % Al 2 O 3 component. The CaO component was calculated to be 9.2% by mass, the CaO component was calculated to be 52.5 to 56.7% by mass, and the MgO component was calculated to be 5.3 to 7.3% by mass. The basicity of the slag increased to approximately 2.0, and the amount of slag dripped decreased to about one-tenth of that in conventional tests, which deteriorated the gas permeability to a point outside the range where the test could be continued stably. .
　スラグの滴下量を増加させるには、生成するスラグの塩基度を下げることが必要であると考えた。そこで、鉄系原料と副原料との原料総成分の塩基度を０．９５～２．２３の範囲内で変更させて、羽口前の炉内で高濃度還元ガスを生成させる試験を行い、溶融物滴下量及び通気抵抗指数ＫＳに及ぼす原料総成分の塩基度の影響を調査した。 In order to increase the amount of slag dripped, we considered it necessary to lower the basicity of the slag produced. Therefore, we conducted a test in which the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials was varied within the range of 0.95 to 2.23, and a highly concentrated reducing gas was generated in the furnace in front of the tuyere. The influence of the basicity of the total raw material components on the melt dripping amount and the ventilation resistance index KS was investigated.
　溶融物滴下量は、試験中に滴下した溶融物を実験後に回収し、重量計でその総重量を測定した。通気抵抗指数ＫＳは、炉内の温度が１０００℃以上の領域において測定された圧力損失と、操業条件より推定される物性値とをもとに算出された通気抵抗Ｋ値（１/ｍ）の積分値として算出した。 The amount of melt dropped was determined by collecting the melt dropped during the test after the experiment and measuring its total weight using a weighing scale. The ventilation resistance index KS is the ventilation resistance K value (1/m) calculated based on the pressure loss measured in the area where the temperature inside the furnace is 1000°C or higher and the physical property values estimated from the operating conditions. Calculated as an integral value.
　＜通気抵抗指数ＫＳの算出方法＞
　通気抵抗Ｋ値（１/ｍ）は、下記の（１）式で算出される。
　Ｋ＝（ΔＰ/Ｈ）/（ρgas 0.7×μgas 0.3×ｖgas 1.7）・・・（１）
　ここで、ΔＰは圧力損失（Ｐａ）であり、Ｈは炉内充填層層厚（ｍ）であり、ρgasはガス密度（ｋｇ/ｍ３）であり、μgasはガス粘度（Ｐａ・ｓ）であり、ｖgasはガス流速（ｍ/ｓ）である。ΔＰは、羽口と試験炉上部（充填層よりも上部空間）の炉壁に圧力計を設置して圧力の差分を計算することで求められる。Ｈは、充填層表面の位置を、例えば試験炉上部に穿孔した穴から測定用治具を差し込んで測定し、充填層表面位置と羽口が設置された位置との高さ方向の距離をＨとして用いる。充填層表面の位置は、レーザー距離計を用いて測定してもよい。ρｇａｓは、羽口から導入したガス成分と、炉内の温度と、炉内の圧力とから算出できる。μｇａｓは、羽口から導入したガス成分と、炉内の温度とから算出できる。ｖｇａｓは、羽口から導入したガス流量と、炉内の温度と、炉内の圧力とから算出できる。ここで、炉内の温度は、充填層に対応した位置の炉壁に複数の温度計を設置し、当該温度計の測定値の平均値を用いる。同様に、炉内の圧力は、充填層に対応した位置の炉壁に複数の温度計を設置し、当該圧力計の測定値の平均値を用いる。ΔＰの算出に用いた羽口の圧力と、充填層上部の圧力との平均値を炉内の圧力として用いてもよい。 <How to calculate ventilation resistance index KS>
The ventilation resistance K value (1/m) is calculated using the following equation (1).
K=(ΔP/H)/(ρ gas 0.7 ×μ gas 0.3 ×v gas 1.7 )...(1)
Here, ΔP is the pressure loss (Pa), H is the thickness of the packed bed in the furnace (m), ρ gas is the gas density (kg/m 3 ), and μ gas is the gas viscosity (Pa・s ), and v gas is the gas flow velocity (m/s). ΔP is obtained by installing pressure gauges on the tuyere and the furnace wall in the upper part of the test furnace (in the space above the packed bed) and calculating the difference in pressure. H is measured by inserting a measuring jig into a hole drilled in the upper part of the test furnace to measure the position of the surface of the packed bed, and then calculating the distance in the height direction between the surface position of the packed bed and the position where the tuyeres are installed. used as The position of the filled layer surface may be measured using a laser distance meter. ρ gas can be calculated from the gas component introduced from the tuyere, the temperature inside the furnace, and the pressure inside the furnace. μ gas can be calculated from the gas components introduced from the tuyere and the temperature inside the furnace. v gas can be calculated from the gas flow rate introduced from the tuyere, the temperature inside the furnace, and the pressure inside the furnace. Here, for the temperature inside the furnace, a plurality of thermometers are installed on the furnace wall at positions corresponding to the packed bed, and the average value of the measured values of the thermometers is used. Similarly, for the pressure inside the furnace, a plurality of thermometers are installed on the furnace wall at positions corresponding to the packed bed, and the average value of the measured values of the pressure gauges is used. The average value of the pressure at the tuyere used to calculate ΔP and the pressure at the top of the packed bed may be used as the pressure in the furnace.
　通気抵抗指数ＫＳは、下記の（２）式で算出される。 The ventilation resistance index KS is calculated using the following formula (2).
Figure JPOXMLDOC01-appb-M000002
  
Figure JPOXMLDOC01-appb-M000002
  
　（２）式において、Ｔｍａｘは、炉内圧力損失を測定した最高温度であり、測定の都度異なるが１５００～１６５０℃程度である。 In formula (2), Tmax is the maximum temperature at which the pressure loss in the furnace was measured, and is approximately 1500 to 1650°C, although it varies depending on the measurement.
　図２は、羽口前の炉内で高濃度還元ガスを生成させる試験において、溶融物滴下量に及ぼす原料総成分の塩基度の影響を示すグラフである。図２の横軸は原料総成分の塩基度（質量％ＣａＯ／質量％ＳｉＯ２）であり、縦軸は溶融物滴下量（ｇ）である。 FIG. 2 is a graph showing the influence of the basicity of the total raw material components on the amount of melt dripping in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere. The horizontal axis of FIG. 2 is the basicity of the total raw material components (mass % CaO/mass % SiO 2 ), and the vertical axis is the melt dropping amount (g).
　図３は、羽口前の炉内で高濃度還元ガスを生成させる試験において、通気抵抗指数ＫＳに及ぼす原料総成分の塩基度の影響を示すグラフである。図３の横軸は原料総成分の塩基度（質量％ＣａＯ／質量％ＳｉＯ２）であり、縦軸は通気抵抗指数ＫＳ（１０５℃／ｍ）である。 FIG. 3 is a graph showing the influence of the basicity of the total raw material components on the ventilation resistance index KS in a test in which highly concentrated reducing gas is generated in the furnace in front of the tuyere. The horizontal axis of FIG. 3 is the basicity of the total raw material components (mass% CaO/mass% SiO 2 ), and the vertical axis is the ventilation resistance index KS (10 5 °C/m).
　図２に示すように、鉄系原料と副原料との原料総成分の塩基度が１．０～１．７の範囲内で、溶融物滴下量は増加した。また、図３に示すように、鉄系原料と副原料との原料総成分の塩基度が１．０～１．７の範囲内で、通気抵抗指数ＫＳが目標値である２０００以下に低下することが確認された。通気抵抗指数ＫＳの目標値２０００は、安定した試験が継続可能となる閾値である。安定した試験とは、充填層表面高さが時間に対して均一に低下し、吹き抜け等のトラブルが生じない試験を意味する。 As shown in FIG. 2, the amount of melt dropped increased when the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials was within the range of 1.0 to 1.7. In addition, as shown in Figure 3, when the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials is within the range of 1.0 to 1.7, the ventilation resistance index KS decreases to the target value of 2000 or less. This was confirmed. The target value of 2000 for the ventilation resistance index KS is a threshold value at which stable testing can be continued. A stable test means a test in which the surface height of the packed bed decreases uniformly over time and no problems such as blow-through occur.
　これらの結果から、鉄系原料と副原料との原料総成分の塩基度を１．０～１．７の範囲内にすることで、羽口前の炉内で高濃度還元ガスを生成させる試験を安定して行えることが確認された。 Based on these results, we conducted a test to generate high-concentration reducing gas in the furnace in front of the tuyere by keeping the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials within the range of 1.0 to 1.7. It was confirmed that this can be done stably.
　本実施形態に係る高炉の操業方法は、上記試験結果に基づきなされたものであり、高炉の炉頂から鉄系原料、副原料及びコークスを装入し、高炉の羽口から羽口前の炉内で高濃度還元ガスを発生させるガスを吹き込む高炉の操業方法であって、装入する鉄系原料と装入する副原料との原料総成分の塩基度を所定範囲内にする高炉操業方法である。 The operating method of the blast furnace according to the present embodiment was made based on the above test results, and consists of charging iron-based raw materials, auxiliary raw materials, and coke from the top of the blast furnace, and charging the iron-based raw materials, auxiliary raw materials, and coke from the tuyere of the blast furnace to the furnace in front of the tuyere. A method of operating a blast furnace in which a gas that generates high concentration reducing gas is injected into the blast furnace, the method of operating a blast furnace in which the basicity of the total raw material components of the iron-based raw materials to be charged and the auxiliary raw materials to be charged is within a predetermined range. be.
　ここで、装入する鉄系原料と装入する副原料との原料総成分の塩基度は１．０以上１．７以下の範囲内であることが好ましい。これにより、高炉炉下部における溶融物の滴下性と通気性を向上できる。鉄系原料と副原料との原料総成分の塩基度が１．０未満の場合、及び、鉄系原料と副原料との原料総成分の塩基度が１．７超の場合は、ともに、スラグの粘度が上昇して安定操業範囲外となるので好ましくない。 Here, the basicity of the total raw material components of the iron-based raw material to be charged and the auxiliary raw materials to be charged is preferably within the range of 1.0 or more and 1.7 or less. Thereby, the dripping property and air permeability of the melt in the lower part of the blast furnace can be improved. When the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials is less than 1.0, and when the basicity of the total raw material components of iron-based raw materials and auxiliary raw materials is more than 1.7, both slag This is not preferable because the viscosity of the liquid increases and goes out of the stable operation range.
　なお、装入する鉄系原料と副原料との原料総成分の塩基度は１．１以上１．７以下であることがより好ましく、１．４以上１．５以下であることがさらに好ましい。これにより、スラグの粘度がさらに低下し、溶融物の滴下性と通気性がさらに向上できる。原料調整に当たっては、スラグ量を４００ｋｇ/溶銑－ｔｏｎ以下にすることが好ましい。スラグ量を４００ｋｇ/溶銑－ｔｏｎ以下にすることで、低温度域から溶け出す溶融物量の増加による通気性の低下を抑制できる。 Note that the basicity of the total raw material components of the iron-based raw materials and auxiliary raw materials to be charged is more preferably 1.1 or more and 1.7 or less, and even more preferably 1.4 or more and 1.5 or less. This further reduces the viscosity of the slag and further improves the dripping properties and air permeability of the melt. When adjusting raw materials, it is preferable to keep the amount of slag to 400 kg/ton of hot metal or less. By setting the amount of slag to 400 kg/ton of hot metal or less, it is possible to suppress a decrease in air permeability due to an increase in the amount of melt that melts from a low temperature range.
　また、高濃度還元ガスは、当該高濃度還元ガス中のＨ２ガス量（炭化水素中の水素を含む）が０～５００Ｎｍ３／溶銑－ｔｏｎの範囲内であることが好ましい。これにより、炉内温度の低下及び還元反応速度の低下を抑制できる。一方、高濃度還元ガス中のＨ２ガス量が５００Ｎｍ３／溶銑－ｔｏｎを超えると、炉内温度が低下し、還元反応速度が低下するため、好ましくない。また、Ｈ２ガスを単体で吹込む場合、羽口前温度を操業範囲内に保つためにＨ２ガスを加熱してから送風することが好ましい。 Further, it is preferable that the amount of H 2 gas (including hydrogen in hydrocarbons) in the high concentration reducing gas is within the range of 0 to 500 Nm 3 /ton of hot metal. Thereby, it is possible to suppress a decrease in the temperature inside the furnace and a decrease in the reduction reaction rate. On the other hand, if the amount of H 2 gas in the high-concentration reducing gas exceeds 500 Nm 3 /ton of hot metal, the furnace temperature will drop and the reduction reaction rate will decrease, which is not preferable. Further, when blowing H 2 gas alone, it is preferable to heat the H 2 gas before blowing in order to maintain the temperature before the tuyere within the operating range.
　以上説明したように、本実施形態に係る高炉の操業方法では、羽口前の炉内で高濃度還元ガスを発生させる高炉操業を実施するに際し、装入する鉄系原料と装入する副原料との原料総成分の塩基度を所定範囲内に制御する。これにより、高炉内の融着帯及び滴下帯で生成するスラグの粘度が最適化され、高炉内でのスラグの通液性が操業可能範囲に制御されて、高炉内のガス通気性を良好に保ち、安定操業を実現できる。 As explained above, in the blast furnace operating method according to the present embodiment, when carrying out a blast furnace operation that generates high concentration reducing gas in the furnace before the tuyere, the iron-based raw material to be charged and the auxiliary raw material to be charged are The basicity of the total raw material components is controlled within a predetermined range. As a result, the viscosity of the slag generated in the cohesive zone and dripping zone in the blast furnace is optimized, and the liquid permeability of the slag in the blast furnace is controlled within the operational range, resulting in good gas permeability in the blast furnace. This allows stable operation to be achieved.
　大型高炉を用いて、炉頂から鉄系原料、副原料及びコークスを交互に装入し、炉頂から装入する鉄系原料と副原料との原料総成分の塩基度を変化させて、羽口前の炉内で高濃度還元ガスを生成させる高炉操業試験を実施した。表２に、試験結果の一例を示す。 Using a large blast furnace, ferrous raw materials, auxiliary raw materials and coke are charged alternately from the top of the furnace, and the basicity of the total raw material components of the ferrous raw materials and auxiliary raw materials charged from the top of the furnace is changed to A blast furnace operation test was conducted in which highly concentrated reducing gas was generated in the furnace in front of the blast furnace. Table 2 shows an example of the test results.
Figure JPOXMLDOC01-appb-T000003
  
Figure JPOXMLDOC01-appb-T000003
  
　表２に示すとおり、炉頂から装入する鉄系原料と副原料との原料総成分の塩基度を本発明の範囲とした発明例１～４では、滴下性及び通気性が良好で、安定操業が可能であることが確認された。一方、炉頂から装入する鉄系原料と副原料との原料総成分の塩基度が本発明の範囲外である比較例１～３では、十分な滴下量は得られず、通気性も不良であった。 As shown in Table 2, in Invention Examples 1 to 4, in which the basicity of the total raw material components of the iron-based raw materials and auxiliary raw materials charged from the top of the furnace was within the range of the present invention, the dripping performance and air permeability were good, and the stability was good. It was confirmed that operation is possible. On the other hand, in Comparative Examples 1 to 3, in which the basicity of the total raw material components of the iron-based raw materials and auxiliary raw materials charged from the top of the furnace was outside the range of the present invention, a sufficient dripping amount could not be obtained and the air permeability was also poor. Met.

Claims (5)

  1. 　高炉の炉頂から鉄系原料、副原料及びコークスを装入し、高炉の羽口から羽口前の炉内で高濃度還元ガスを発生させるガスを吹き込む高炉の操業方法であって、前記鉄系原料と前記副原料との原料総成分の塩基度を所定範囲内にする、高炉の操業方法。 A method of operating a blast furnace in which iron-based raw materials, auxiliary raw materials, and coke are charged from the top of the blast furnace, and gas is blown into the blast furnace from the tuyere to generate high-concentration reducing gas in the furnace before the tuyere, the method comprising: A blast furnace operating method in which the basicity of the total raw material components of the system raw material and the auxiliary raw material is within a predetermined range.
  2. 　前記原料総成分の塩基度を１．０以上１．７以下の範囲内にする、請求項１に記載の高炉の操業方法。 The method for operating a blast furnace according to claim 1, wherein the basicity of the total raw material components is within a range of 1.0 or more and 1.7 or less.
  3. 　前記高濃度還元ガスは、ボッシュガス組成として表すと、Ｈ２ガス、Ｎ２ガス及びＣＯガスで構成され、Ｈ２ガス、Ｎ２ガス及びＣＯガスの割合が、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムにおけるＨ２ガス；０体積％、Ｎ２ガス；０体積％、ＣＯガス；１００体積％の点と、Ｈ２ガス；１００体積％、Ｎ２ガス；０体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；２９体積％、Ｎ２ガス；７１体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；０体積％、Ｎ２ガス；３７体積％、ＣＯガス；６３体積％の点との４点で囲まれる領域内の組成であり、０～１００体積％の範囲内のＨ２ガスと、０～７１体積％の範囲内のＮ２ガスと、０～１００体積％の範囲内のＣＯガスとを含む、請求項１に記載の高炉の操業方法。 Expressed as a Bosch gas composition, the high concentration reducing gas is composed of H 2 gas, N 2 gas and CO gas, and the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas - In the ternary diagram of CO gas, H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %, and H 2 gas; 100 volume %, N 2 gas; 0 volume %, CO gas; 0 volume % point, H 2 gas; 29 volume %, N 2 gas; 71 volume %, CO gas; 0 volume % point, H 2 gas; 0 volume %, N 2 gas; 37 volume. %, CO gas; composition within the area surrounded by the 4 points with the 63 volume % point, H 2 gas within the range of 0 to 100 volume %, and N 2 gas within the range of 0 to 71 volume % and CO gas within a range of 0 to 100% by volume, the method for operating a blast furnace according to claim 1.
  4. 　前記高濃度還元ガスは、ボッシュガス組成として表すと、Ｈ２ガス、Ｎ２ガス及びＣＯガスで構成され、Ｈ２ガス、Ｎ２ガス及びＣＯガスの割合が、Ｈ２ガス－Ｎ２ガス－ＣＯガスの３元系ダイアグラムにおけるＨ２ガス；０体積％、Ｎ２ガス；０体積％、ＣＯガス；１００体積％の点と、Ｈ２ガス；１００体積％、Ｎ２ガス；０体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；２９体積％、Ｎ２ガス；７１体積％、ＣＯガス；０体積％の点と、Ｈ２ガス；０体積％、Ｎ２ガス；３７体積％、ＣＯガス；６３体積％の点との４点で囲まれる領域内の組成であり、０～１００体積％の範囲内のＨ２ガスと、０～７１体積％の範囲内のＮ２ガスと、０～１００体積％の範囲内のＣＯガスとを含む、請求項２に記載の高炉の操業方法。 Expressed as a Bosch gas composition, the high concentration reducing gas is composed of H 2 gas, N 2 gas and CO gas, and the ratio of H 2 gas, N 2 gas and CO gas is H 2 gas - N 2 gas - In the ternary diagram of CO gas, H 2 gas; 0 volume %, N 2 gas; 0 volume %, CO gas; 100 volume %, and H 2 gas; 100 volume %, N 2 gas; 0 volume %, CO gas; 0 volume % point, H 2 gas; 29 volume %, N 2 gas; 71 volume %, CO gas; 0 volume % point, H 2 gas; 0 volume %, N 2 gas; 37 volume. %, CO gas; composition within the area surrounded by the 4 points with the 63 volume % point, H 2 gas within the range of 0 to 100 volume %, and N 2 gas within the range of 0 to 71 volume % and CO gas within a range of 0 to 100% by volume, the method for operating a blast furnace according to claim 2.
  5. 　前記高濃度還元ガス中のＨ２ガス量は０～５００Ｎｍ３／溶銑－ｔｏｎの範囲内である、請求項１から請求項４のいずれか一項に記載の高炉の操業方法。 The method of operating a blast furnace according to any one of claims 1 to 4, wherein the amount of H 2 gas in the high concentration reducing gas is within a range of 0 to 500 Nm 3 /ton of hot metal.
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JP2013082971A (en) * 2011-10-11 2013-05-09 Nippon Steel & Sumitomo Metal Corp Method for operating blast furnace
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JPH09143516A (en) * 1995-11-17 1997-06-03 Nippon Steel Corp Operation of vertical type furnace
JP2002060809A (en) * 2000-08-08 2002-02-28 Nippon Steel Corp Low furnace heat blast furnace operation method using sintered ore having controlled chemical composition
WO2011021577A1 (en) * 2009-08-21 2011-02-24 新日本製鐵株式会社 Unfired carbon-containing agglomerate for blast furnaces and production method therefor
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