JP2022134616A - Carbon-containing agglomerated ore for blast furnace and blast furnace operation method using the same - Google Patents

Abstract

To provide carbon-containing agglomerated ore for a blast furnace, which can reduce a reducing material ratio more, and a blast furnace operation method using the ore.MEANS FOR SOLVING THE PROBLEM: In order to solve the problem, according to one aspect of the present invention, provided is carbon-containing agglomerated ore for a blast furnace which contains 70 mass% or more of carbon, metallic iron, and iron oxide in total. A carbon content is 15-25 mass% relative to the total mass of the carbon-containing agglomerated ore for a blast furnace, and a mass ratio of metallic iron to carbon is 0.4-0.8.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a coal-containing agglomerate ore for blast furnace and a method of operating a blast furnace using the same.

In the steel industry, the blast furnace process is the mainstream of the pig iron manufacturing process. In the blast furnace method, iron-based raw materials for blast furnaces (mainly sintered ore) and coke are alternately and layeredly charged into the blast furnace from the top of the blast furnace, while hot air is blown into the blast furnace from the tuyeres at the bottom of the blast furnace. The hot air reacts with the pulverized coal blown together with the hot air and coke in the blast furnace to generate high-temperature reducing gas (here, mainly CO gas). That is, hot air gasifies coke and pulverized coal. The reducing gas rises in the blast furnace and reduces the iron-based raw material while heating it. The iron-based raw material is heated and reduced by the reducing gas while descending in the blast furnace. After that, the iron-based raw material melts and drips into the blast furnace while being further reduced by coke. The iron-based raw material is finally stored in the hearth as molten pig iron (pig iron) containing a little less than 5% by mass of carbon. Molten iron in the hearth is taken out from the tap hole and supplied to the next steelmaking process. Therefore, in the blast furnace method, carbonaceous materials such as coke and pulverized coal are used as reducing agents.

By the way, in recent years, the prevention of global warming has been called for, and the reduction of emissions of carbon dioxide (CO ₂ gas), which is one of the greenhouse gases, has become a social issue. As mentioned above, the blast furnace process uses carbonaceous material as a reducing agent, so it generates a large amount of _CO2 gas. Therefore, the steel industry has become one of the major industries in terms of _CO2 gas emissions and must meet the social demands. Specifically, there is an urgent need to further reduce the reducing agent ratio (the amount of reducing agent used per ton of hot metal, also called RAR) in blast furnace operation.

As one of techniques for reducing the reducing agent ratio, it is known to use coal-containing agglomerate ore as a substitute for a part of sintered ore. Here, the coal-containing agglomerated ore is obtained by blending an iron oxide raw material such as iron ore with a carbonaceous material and agglomerating the mixture. In the coal-containing agglomerate ore, since the iron oxide raw material and the carbonaceous material are close to each other, the carbon (component C) in the carbonaceous material is easily gasified due to the coupling effect. Therefore, the use of coal-containing agglomerate ore as an iron-based raw material for blast furnaces is expected to reduce the reducing agent ratio.

On the other hand, it is well known that metallic iron has a catalytic action to promote gasification of carbon (promote carbon reactivity). Ferro-coke using the catalytic action of such metallic iron is also widely studied. Ferro-coke is produced, for example, by mixing low-grade coal and iron ore, molding the mixture, and then heating the mixture while shutting off the air.

Patent Literature 1 and Non-Patent Literatures 1 and 2 disclose a technique that combines the technology of coal-containing agglomerate ore and ferro-coke, that is, a technique of further mixing metallic iron (M.Fe) with coal-containing agglomerate ore. ing.

JP 2012-92389 A

Iguchi et al.: Tetsu to Hagane, Vol. 88 (2002), No. 9, p. 479-486 Nishimura et al.: CAMP-ISIJ, Vol. 18 (2005), P. 929

However, in a coal-containing agglomerate ore containing metallic iron, no suitable combination condition of metallic iron and carbon has been known so far, and the advantages of the above-mentioned coal-containing agglomerate ore and ferro-coke are fully utilized. It was hard to say.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a coal-containing agglomerate ore for blast furnaces capable of further reducing the reducing agent ratio, and a blast furnace operation using the same. to provide a method.

In order to solve the above problems, according to one aspect of the present invention, a carbon-containing agglomerate ore for blast furnace containing a total of 70% by mass or more of carbon, metallic iron, and iron oxide, wherein the carbon content is A coal-containing agglomerate for blast furnace, characterized in that it is 15 to 25% by mass with respect to the total mass of the coal-containing agglomerate ore for blast furnace, and the mass ratio of metallic iron to carbon is 0.4 to 0.8. ore is provided.

According to another aspect of the present invention, there is provided a method for operating a blast furnace using the above-described coal-containing agglomerate ore for blast furnace use, wherein the carbon intensity derived from the coal-containing agglomerate ore for blast furnace use is 5 to 30 kg/t-HM. A method for operating a blast furnace is provided, characterized by:

ADVANTAGE OF THE INVENTION According to the said viewpoint of this invention, the coal-containing agglomerate for blast furnaces which can reduce a reducing material ratio more, and the operating method of a blast furnace using the same can be provided.

4 is a graph showing a comparison between the range of the combination of metallic iron and carbon according to the present embodiment and the conventional range. It is a graph for demonstrating the preferable mass ratio of metallic iron and carbon.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The present inventors have extensively studied the composition of coal-containing agglomerates for blast furnaces containing metallic iron (hereinafter also simply referred to as "coal-containing agglomerates"), and as a result, have found suitable conditions for combining metallic iron and carbon. was able to find Based on such knowledge, the present inventor was able to come up with the coal-containing agglomerate ore according to the present embodiment and the method of operating a blast furnace using the same. In the present embodiment, "carbon" means "carbon (C) component" contained in "carbonaceous material" rather than "carbonaceous material" itself used in coal-containing agglomerates or the like. do. "Iron oxide" includes wustite (FeO), magnetite _{( Fe3O4} ) and hematite _{( Fe2O3} ). Further, the unit "/t-HM" according to the present embodiment indicates the amount required to manufacture 1 ton of hot metal, that is, the so-called basic unit. In the present embodiment, a numerical range represented using "-" means a range including the numerical values described before and after "-" as lower and upper limits. Hereinafter, the coal-containing agglomerate ore and the method of operating a blast furnace using the same according to the present embodiment will be described in detail.

<1. Composition of coal-bearing agglomerate>
The coal-containing agglomerate ore according to the present embodiment contains at least carbon, metallic iron, and iron oxide in a total amount of 70% by mass or more with respect to the total mass of the coal-containing agglomerate ore. If this condition is not met, the reducing agent ratio cannot be sufficiently reduced. That is, the coal-containing agglomerate ore is mainly composed of carbon, metallic iron, and iron oxide, and the balance is composed of slag (CaO, SiO ₂ , Al ₂ O ₃ , etc.), water of crystallization, and the like. A low content of carbon, metallic iron, and iron oxide results in an increase in slag components. Therefore, the reducing agent required for dissolving the slag components in the blast furnace increases, and thus the reducing agent ratio increases.

Furthermore, in the coal-containing agglomerate ore according to the present embodiment, the carbon content is 15 to 25% by mass with respect to the total mass of the coal-containing agglomerate ore for blast furnace use. When the carbon content falls within this range, the effect of carbon is effectively exhibited, and the reducing agent ratio is reduced. Here, the effects of carbon include the effect of promoting gasification of carbon (so-called coupling effect) due to the proximity of carbon to iron oxide, and the effect of promoting gasification of carbon due to the catalytic action of metallic iron. A preferable upper limit of the carbon content is 20% by mass. That is, the carbon content is preferably 15-20 mass %.

If the carbon content is less than 15% by mass, the effect of carbon cannot be fully enjoyed, and the reducing agent ratio is not sufficiently reduced. That is, since reducing gas (CO) is easily generated from the coal-containing agglomerate ore, it contributes to the reduction of the reducing agent ratio. However, if the carbon content is less than 15% by mass, the reducing gas itself generated from the carbon-containing agglomerate ore is reduced in the first place, so the reducing material ratio is not sufficiently reduced.

On the other hand, when the carbon content exceeds 25% by mass, the content of iron oxide in the carbon-containing agglomerate ore, that is, the amount of oxygen to be reduced (the amount of oxygen bound to iron oxide) becomes extremely small. Therefore, the effects of carbon cannot be sufficiently enjoyed. That is, reducing gas (CO) is easily generated from the coal-bearing agglomerate ore. However, if the carbon content exceeds 25% by mass, the amount of reducible oxygen present in the immediate vicinity of the reducing gas is reduced, so that the effects of the reducing gas cannot be fully enjoyed. That is, the effects of carbon cannot be sufficiently enjoyed. Furthermore, if the carbon content exceeds 25% by mass, the hot strength of the carbon-containing agglomerate ore may decrease, and the operation may become unstable. As a result of these, not only the reducing agent ratio is not sufficiently reduced, but there is also the possibility that it may even increase.

Furthermore, the mass ratio (M.Fe/T.C) of metallic iron and carbon is 0.4 to 0.8. In this case, the catalytic action of metallic iron provides a sufficient effect of promoting the gasification of carbon, thereby reducing the reducing agent ratio. When the mass ratio of metallic iron and carbon is less than 0.4, the gasification promotion effect of carbon is not sufficiently obtained, especially when the blast furnace is operated at 50 to 150 kg / t-HM, the reducing agent ratio is sufficient. does not reduce to On the other hand, when the mass ratio of metallic iron and carbon exceeds 0.8, the amount of carbon becomes relatively low, and the effect of carbon cannot be fully enjoyed. In other words, since metallic iron is sufficiently present, the gasification of carbon is sufficiently promoted, but since the amount of reducing gas itself generated is reduced in the first place, the reducing material ratio is not sufficiently reduced. That is, the effects of carbon cannot be sufficiently enjoyed. A preferable lower limit of the mass ratio (M.Fe/T.C) of metallic iron and carbon (M.Fe/T.C) is 0.5, and a preferable upper limit is 0.7.

FIG. 1 is a graph showing a comparison between the range of the combination of metallic iron and carbon according to the present embodiment and the conventional range.

The horizontal axis of FIG. 1 indicates the content (% by mass) of carbon (T.C) contained in the coal-bearing agglomerate ore, and the vertical axis indicates the content of metallic iron (M.Fe) contained in the coal-bearing agglomerate ore. Amount (% by mass) is indicated. Graph L1 is M. Fe/T. C=0.8 and graph L2 shows M.C=0.8. Fe/T. C=0.4 is shown. Graphs L3 and L4 indicate carbon content=15% by mass and 25% by mass, respectively. Therefore, the area A1 surrounded by the graphs L1 to L4 indicates the conditions (combination conditions of metallic iron and carbon) to be satisfied by the carbon-containing agglomerate ore according to the present embodiment.

On the other hand, area B indicates the range disclosed in Non-Patent Document 2, and points C1, C2, and a graph C connecting them indicate the range disclosed in Patent Document 1. Although illustration is omitted, in Non-Patent Document 1, the carbon content is approximately 10% by mass. Therefore, both ranges are outside the range that the coal-containing agglomerate ore according to the present embodiment should satisfy.

FIG. 2 is a graph for explaining a preferable mass ratio of metallic iron and carbon contained in the coal-containing agglomerate ore. Specifically, FIG. 2 shows the relationship between the mass ratio (M.Fe/T.C) of metallic iron and carbon contained in the coal-bearing agglomerate ore and the reducing agent ratio RAR (kg/t-HM). is shown for each carbon content contained in the coal-containing agglomerate ore (% by mass with respect to the total mass of the coal-containing agglomerate ore). The horizontal axis of FIG. 2 indicates the mass ratio (M.Fe/T.C) of metallic iron and carbon contained in the coal-bearing agglomerate ore, and the vertical axis indicates the reducing agent ratio RAR (kg/t-HM). The reducing agent ratio is a value measured in Examples described later. In the examples, the reducing agent ratio was measured using a BIS furnace (Naito et al.: Tetsu to Hagane, Vol. 87 (2001), No. 5, pp. 357-364) simulating a blast furnace. The detailed test conditions were the same as those of the examples described later, and the unit carbon consumption derived from the coal-containing agglomerate ore was set to 20 kg/t-HM.

Point P10 is the M.O.M. Fe/T. Measured values of C and the reducing agent ratio are shown, and graph L10 is a graph connecting points P10. Point P20 is the M.O.D. when the carbon content is 25% by mass. Fe/T. Measured values of C and the reducing agent ratio are shown, and graph L20 is a graph connecting points P20. Graphs L30 and L40 are M.M. Fe/T. C = 0.4, 0.8. A region A2 surrounded by graphs L10 to L40 indicates conditions (combination conditions of metallic iron and carbon) to be satisfied by the carbon-containing agglomerate ore according to the present embodiment. Point P30 indicates a base operation (operation where carbon content=0 mass) in which no carbon-containing agglomerate is used. As is clear from FIGS. 1 and 2, when the conditions of regions A1 and A2 are satisfied, the reducing material ratio is greatly reduced compared to the operation in which the carbon content=0 mass. Also, when the carbon content is compared under the same conditions, when the mass ratio of metallic iron and carbon (M.Fe/T.C) is 0.4 to 0.8, the reducing agent ratio is found to be greatly reduced. In other words, the purpose of the present embodiment is to efficiently use the carbon in the carbon-containing agglomerate ore. We need to compare the effects.

The coal-containing agglomerate ore may satisfy the above conditions, and may further have a C/O of about 1.0 to 2.0. In this case, the reducing agent ratio may be further reduced. C in C/O indicates carbon in the coal-containing agglomerate ore, and O indicates reducible oxygen in the coal-containing agglomerate ore. C/O indicates their molar ratio. Also, the particle size of the coal-containing agglomerate ore is not particularly limited, and may be approximately the same as that of the conventional coal-containing agglomerate ore. For example, the grain size of the coal-bearing agglomerate ore may be about 5 to 15 mm. In addition, the particle size of the coal-containing agglomerate ore can be classified with sieves having different openings. The particle size of the coal-containing agglomerate ore that falls from a sieve with a mesh size of 15 mm and remains on a sieve with a mesh size of 5 mm falls within the range of 5 to 15 mm.

<2. Method for producing coal-bearing agglomerate ore>
Next, a method for producing a coal-containing agglomerate ore according to the present embodiment will be described. The production method itself is not particularly limited, and each raw material may be blended and molded so that the coal-containing agglomerate ore satisfies the above conditions.

Raw materials for producing the coal-containing agglomerate ore include iron oxide raw materials, carbon materials, binders, and the like. Any type of iron oxide raw material can be used, and iron oxide raw materials used for conventional carbon-containing agglomerates can be used without particular limitations. Examples of the iron oxide raw material include converter dust, blast furnace primary ash, sintering dust and the like having the compositions shown in Table 1. Each numerical value in Table 1 is mass % of each component with respect to the total mass of the iron oxide raw material. Further, "T.Fe" in Table 1 means total iron including metallic iron and iron oxide, and "T.C" means carbon contained in the iron oxide raw material. A plurality of types of iron oxide raw materials may be mixed and used, or any iron oxide raw material may be used alone. However, in the present embodiment, since it is necessary to mix metallic iron with the coal-containing agglomerate ore, it is necessary to use an iron oxide raw material containing at least metallic iron. In this regard, since the primary blast furnace ash shown in Table 1 contains 50% by mass or more of metallic iron, it is suitable as an iron oxide raw material for producing the coal-containing agglomerate ore according to the present embodiment. That is, by using an iron oxide raw material containing 50% by mass or more of metallic iron, it becomes easy to adjust the mass ratio (M.Fe/TC) of metallic iron and carbon. Moreover, when the metallic iron content is insufficient, a metallic iron source such as reduced iron powder or scrap may be separately purchased and used as appropriate. However, from the viewpoint of resource saving and recycling, it is preferable to use converter dust, blast furnace primary ash, sintering dust, etc., without using metallic iron sources as much as possible.

The type of carbonaceous material that is the raw material of the coal-containing agglomerate ore is not particularly limited, and the carbonaceous materials used in conventional coal-containing agglomerate ore can be suitably used in the present embodiment. Examples of carbonaceous materials include coke, coal, anthracite, coke dust (dust generated during the coke manufacturing process), coal char, and the like.

The type of binder used as a raw material for the coal-containing agglomerate ore is not particularly limited, and binders used for conventional coal-containing agglomerate ore can be suitably used in the present embodiment. For example, binders include hydraulic binders, more specifically cements (high-early-strength Portland cement, etc.).

The components of each raw material can be specified by a general chemical analysis method or a fluorescent X-ray analysis method. Therefore, each raw material may be blended and molded so that the coal-containing agglomerate ore satisfies the above conditions. For example, after kneading and molding the blended raw materials and an appropriate amount of water in a granulator such as a pelletizer or briquette machine, the mixture is cured (hardened the binder) to form a coal-containing agglomerate ore.

<3. Blast Furnace Operation Method>
Next, a method for operating a blast furnace according to this embodiment will be described. In this embodiment, the blast furnace is operated by substituting part of the iron-based raw material (sintered ore, etc.) with the coal-containing agglomerate ore according to this embodiment. Here, it is preferable to set the carbon intensity derived from the coal-containing agglomerate ore to 5 to 30 kg/t-HM. In this case, the reducing material ratio is further reduced. If the carbon intensity derived from the coal-containing agglomerate ore is less than 5 kg/t-HM, the reducing agent ratio may not be sufficiently reduced. On the other hand, when the carbon intensity derived from the coal-containing agglomerate ore exceeds 30 kg/t-HM, the effect of improving the reducing agent ratio is saturated. Operations other than the above may be performed in the same manner as in the conventional blast furnace operation method.

Next, an example of this embodiment will be described. In this example, the following tests were conducted in order to verify the effects of this embodiment. Of course, the invention is not limited to the examples described below. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

First, iron oxide raw materials shown in Table 1, actual coke dust, reagent iron powder (purity 98%), and early-strength Portland cement were prepared. The iron oxide raw material and the components of the actual coke dust were identified by fluorescent X-ray analysis. In addition, the particle size of each raw material was 50 μm, 53 μm, 50 μm and 13 μm in terms of d50 (volume basis). Here, d50 of each raw material was measured by the following measuring method using a laser diffraction particle size distribution analyzer. That is, a sample to be measured was slurried with water, and a small amount of sodium hexametaphosphate solution was added as a dispersant. Then, the sample was dispersed in the mixed liquid by stirring the mixed liquid and applying ultrasonic waves. Next, this mixed liquid was set in a laser diffraction particle size distribution analyzer, the particle size distribution was measured, and d50 was specified.

Then, these raw materials were blended with an appropriate amount of water and molded with a briquette machine. Then, the molded granules were cured. By repeating the above steps while changing the type of iron oxide raw material and the blending ratio of each raw material, coal-containing agglomerates (Test Example Nos. 1 to 22) having the compositions shown in Table 2 were produced. Among the produced coal-bearing agglomerate ores, those having a particle size of 8 to 13 mm (dropped from a sieve with an opening of 13 mm and remaining on a sieve with an opening of 8 mm) were used in the following BIS furnace tests.

Each component in Table 2 shows the mass %, molar ratio, basic unit, etc. of each component in the coal-containing agglomerate ore. For example, "T.Fe" indicates mass% of total iron in the coal-bearing agglomerate, "M.Fe" indicates mass% of metallic iron in the coal-bearing agglomerate, and "TC" indicates The carbon content (% by mass) in the coal-containing agglomerate ore is shown. “FeO” and “Fe ₂ O ₃ ” indicate the content (% by mass) of “iron oxide” in the coal-containing agglomerate ore. "Amount of oxygen to be reduced" indicates mass % of oxygen bound to "iron oxide". “C+M.Fe+FeO+Fe ₂ O ₃ ” indicates the total mass % of carbon, metallic iron and iron oxide in the carbon-containing agglomerate ore. The % by mass of each component is % by mass with respect to the total mass of the sample of the coal-bearing agglomerate ore. "M.Fe/T.C" indicates the mass ratio of metallic iron and carbon in the coal-containing agglomerate ore, and C/O indicates the molar ratio of carbon and reducible oxygen in the coal-containing agglomerate ore.

A BIS furnace test was then performed. The details of the BIS furnace test are as described in "Naito et al.: Tetsu to Hagane, Vol. 87 (2001), No. 5, P. 357-364)", and this test is also in this non-patent document. Performed according to the described method. Specifically, the T.V. C, T. The amount of sintered ore is adjusted so that Fe (T.C, T.Fe here indicates the mass% of carbon in the charged charge with respect to the total mass of the entire charged charge, and the mass% of all iron) is constant. , the amount of coke was adjusted respectively.

In addition, the amount of the coal-containing agglomerate ore used was adjusted so that the carbon unit consumption derived from the coal-containing agglomerate ore was the value shown in Table 2. That is, when using a coal-containing agglomerate ore with a T.C of 15.0% by mass, the amount of coal-containing agglomerate ore used (basic unit) is 133 kg / t-HM, and the T.C is 25.0 mass % coal-containing agglomerate ore, the amount of coal-containing agglomerate ore used (basic unit) was set to 80 kg/t-HM. Furthermore, under a blast temperature of 1178 ° C., a blast moisture content of 18.6 g/Nm ³ , and an oxygen enrichment rate of 2.7%, so that the reducing agent ratio is 481 kg / t-HM and the coke ratio is 349 kg / t-HM. set the bosh gas composition (CO: 36.0% by volume, H ₂ : 7.0% by volume, N ₂ : 57.0% by volume) and the air flow rate (1343 Nm ³ /t-HM).

Here, the oxygen enrichment rate is roughly the volume ratio of oxygen in the hot air to the total volume of the hot air, and the oxygen enrichment rate (%) = {(blowing air volume (flow rate) [Nm ³ / min]×0.21+oxygen enrichment amount [Nm ³ /min])/(air flow rate [Nm ³ /min]+oxygen enrichment amount [Nm ³ /min])}×100−21. Moreover, Ore/Coke (mass ratio of sintered ore and coke) was set to 4.63.

Also, taking into consideration the circulation of alkali in the blast furnace, the reagent KOH was added so that the amount of K was 1.8% by mass with respect to the coke. Based on the shaft efficiency obtained in the BIS furnace, the heat and mass balance was taken to evaluate the reducing agent ratio. At this time, the reducing material ratio was evaluated as a basic unit of the amount of pulverized coal blown with hot air + coke + carbonaceous material in the coal-bearing agglomerate (here, actual coke dust) corrected to the amount equivalent to coke. Moreover, M. in the coal-bearing agglomerate ore The effect of reducing oxygen to be reduced by Fe was indirectly evaluated by correcting the experimental data for hematite without changing the reducing gas amount. That is, M. Since no reducible oxygen is bound to Fe, M.I. If an operation is performed in which the amount of reducing gas is reduced by the amount of Fe, the M.O. The more Fe is, the more reduced iron is apparently produced with less reducing material. However, the effect to be obtained by this embodiment is Rather than reducing the reducing agent ratio due to the absence of oxygen bound to Fe, M. This is the decrease in the reducing agent ratio due to the catalytic action of Fe. Therefore, in the present embodiment, the BIS test is performed without reducing the amount of reducing gas, and the obtained results are compared with those of M.I. The reducing material ratio was evaluated after correcting the state in which all Fe was hematite. For comparison, a base operation (operation corresponding to point P30 in FIG. 2) was also performed without using the coal-containing agglomerate ore.

The results are shown in Table 2 and FIG. As described above, FIG. 2 summarizes the data when the carbon intensity derived from coal-bearing agglomerate ore is 20 kg/t-HM. Test Example No. in Table 2. 1 to 6 are examples in which the carbon content (T.C) contained in the carbon-containing agglomerate ore is 15% by mass. 7 to 12 are examples in which the carbon content (T.C) contained in the carbon-bearing agglomerate ore is 25% by mass. Test example no. In 1 to 12, the basic unit of carbon derived from coal-bearing agglomerate ore is unified at 20 kg/t-HM. Test example no. In 13 to 22, while the content of carbon contained in the coal-containing agglomerate ore is set to 15% by mass or 25% by mass, the carbon intensity derived from the coal-containing agglomerate ore, or the carbon and metal in the coal-containing agglomerate ore This is an example in which the total mass % of iron and iron oxide is varied.

First, Test Example No. Considering 1 to 6, the coal-containing agglomerate ore satisfies the requirements of the present embodiment, and the carbon unit consumption derived from the coal-containing agglomerate ore is 20 kg/t-HM within the range of 5 to 30 kg/t-HM. Test example no. At 3 to 5, a very good reducing agent ratio was obtained. Specifically, the reducing material ratio was 490 kg/t-HM or less.

On the other hand, test example No. which does not satisfy other requirements for coal-bearing agglomerate ore. In Nos. 1, 2, and 6, the reducing agent ratio increased compared to Test Examples 3 to 5, in which the carbon-containing agglomerate ore had the same carbon content. Specifically, Test Example No. 1 and 2, the mass ratio of metallic iron to carbon (M.Fe/T.C) is less than 0.4. 6, the mass ratio of metallic iron to carbon (M.Fe/T.C) exceeds 0.8.

Next, Test Example No. 7 to 12, the coal-containing agglomerate ore satisfies the requirements of the present embodiment, and the carbon intensity derived from the coal-containing agglomerate ore is 20 kg/t-HM within the range of 5 to 30 kg/t-HM. Test example no. In 9 to 11, a very good reducing agent ratio was obtained. Specifically, the reducing material ratio was 480 kg/t-HM or less.

On the other hand, test example No. which does not satisfy other requirements for coal-bearing agglomerate ore. In Nos. 7, 8, and 12, the reducing agent ratio increased compared to Test Examples 7 to 12, in which the carbon content in the carbon-containing agglomerate ore was at the same level. Specifically, Test Example No. 7 and 8, the mass ratio of metallic iron to carbon (M.Fe/T.C) is less than 0.4. In No. 12, the mass ratio of metallic iron to carbon (M.Fe/T.C) exceeds 0.8.

Next, Test Example No. Consider 13-16. Test example no. 13 to 16 are Test Example Nos. 4 in which the carbon intensity derived from the coal-containing agglomerate ore is varied. Specifically, Test Example No. In No. 13, the carbon intensity derived from the coal-containing agglomerate ore is less than 5 kg/t-HM. Test example No. in which the content of carbon contained in the coal-containing agglomerate ore is at the same level. Compared with 1, 2 and 6, Test Example No. Although the effect of reducing the reducing agent ratio was also obtained in Test Example No. 13, Compared to 3-5, the reducing agent ratio increased slightly.

Test example no. 14 and 15 are Test Example Nos. 4, the carbon intensity derived from the coal-containing agglomerate ore is set to 5 kg/t-HM or 30 kg/t-HM, which is the boundary value of the present embodiment. Test example no. In Test Example No. 14 and 15, the content of carbon contained in the carbon-containing agglomerate ore is at the same level. Similar results to 3-5 were obtained.

Test example no. In No. 16, the basic unit of carbon derived from coal-bearing agglomerate ore is over 30 kg/t-HM. Test example No. in which the content of carbon contained in the coal-containing agglomerate ore is at the same level. Compared with 1, 2 and 6, Test Example No. Although the effect of reducing the reducing agent ratio was also obtained in Test Example No. 16, Compared to 3-5, the reducing agent ratio increased slightly. In this case, the effect of reducing the reducing agent ratio was saturated to 485 kg/t-HM. However, as the amount of hot pulverization of the coal-bearing agglomerate ore increased and the ventilation resistance of the shaft part increased, the coke ratio was increased to keep the ventilation resistance constant. As a result, the final RAR was 495 kg/ became t-HM.

Next, Test Example No. Consider 17-20. Test example no. 17 to 20 are Test Example Nos. 10 in which the carbon intensity derived from the coal-containing agglomerate ore is varied. Specifically, Test Example No. In No. 17, the carbon intensity derived from the coal-containing agglomerate ore is less than 5 kg/t-HM. Test example No. in which the content of carbon contained in the coal-containing agglomerate ore is at the same level. Test example No. 7, 8 and 12 are compared. Although the effect of reducing the reducing agent ratio was obtained in Test Example No. 17 as well. Compared to 9-11, the reducing agent ratio increased slightly.

Test example no. 18 and 19 are Test Example Nos. 10, the carbon unit consumption derived from the coal-containing agglomerate ore is set to 5 kg/t-HM or 30 kg/t-HM, which is the boundary value of the present embodiment. Test example no. In Test Example No. 18 and 19, the content of carbon contained in the carbon-containing agglomerate ore is at the same level. Results similar to 9-11 were obtained.

Test example no. In No. 20, the basic unit of carbon derived from coal-bearing agglomerate ore is over 30 kg/t-HM. Test example No. in which the content of carbon contained in the coal-containing agglomerate ore is at the same level. Test example No. 7, 8 and 12 are compared. Although the effect of reducing the reducing agent ratio was obtained even with Test Example No. 20, Compared to 9-11, the reducing agent ratio increased slightly. In this case, the effect of reducing the reducing agent ratio was saturated to 475 kg/t-HM. However, as the amount of hot pulverization of the coal-containing agglomerate ore increased and the ventilation resistance of the shaft part increased, the coke ratio was increased in order to keep the ventilation resistance constant. became t-HM.

Test example no. In Nos. 21 and 22, the total content of carbon, metallic iron, and iron oxide is less than 70% by mass. Therefore, the reducing material ratio was not sufficiently reduced.

Test Example 23 corresponds to Test Example No. 4 in which the carbon content of the coal-containing agglomerate ore is varied. Specifically, the carbon content of the coal-containing agglomerate ore is less than 15%. Since the C/O is not high enough, Test Example No. Compared to 4, the reducing agent ratio increased.

Test Example 24 corresponds to Test Example No. 10 in which the carbon content of the coal-containing agglomerate ore is varied. Specifically, the carbon content of the coal-containing agglomerate ore is more than 25%. The C/O was excessively high, and in addition to the fact that the effect was not efficiently exhibited, the pulverization of the coal-containing agglomerate ore in the furnace became significant, destabilizing the operation of the blast furnace. Compared to 10, the reducing agent ratio increased.

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

Claims (2)

A carbon-containing agglomerate ore for blast furnace containing a total of 70% by mass or more of carbon, metallic iron, and iron oxide,
The carbon content is 15 to 25% by mass with respect to the total mass of the carbon-containing agglomerate ore for blast furnace,
A carbon-containing agglomerate ore for blast furnace, characterized in that the mass ratio of the metallic iron and the carbon is 0.4 to 0.8. A method of operating a blast furnace using the coal-containing agglomerate ore for blast furnace according to claim 1,
A method for operating a blast furnace, characterized in that the carbon unit consumption derived from the coal-containing agglomerate ore for blast furnace is 5 to 30 kg/t-HM.

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