Manufacturing method of carbon material containing ore

Abstract

This invention proposes a method for manufacturing carbon-filled ore, which alters the reduction behavior of existing carbon-filled ore to obtain carbon-filled ore exhibiting higher reducibility. The method for manufacturing carbon-filled ore is a method used in the ironmaking industry for manufacturing carbon-filled ore for molten iron, and uses fibrous carbon precipitated from porous iron by carbonization treatment with a gas containing CO and H2 as the carbon source. A preferred embodiment of the method for manufacturing carbon-filled ore uses iron carbide (Fe3C) or iron carbide (Fe3C) plus over-iron carbide (Fe5C2) as the carbon source.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing materials including coke, lining refractories, and ore inside a blast furnace for use in the ironmaking industry. [Previous Technology]

[0002] In the ironmaking industry, reducing CO2 emissions is an urgent problem to be solved. In particular, the ironmaking process is considered to have relatively large emissions. The ironmaking process is equivalent to the steps of producing pig iron by melting and reducing raw materials. Iron oxide raw materials (sintered ore, lump ore, pellets, etc.) and carbon (C) are charged into a reduction furnace. The carbon gasifies to produce CO, which in turn produces a reduction reaction using carbon (C), as shown in the overall reaction rate formula FeOx + CO → FeOx - 1 + CO2. However, not all the carbon charged is used for reduction. By efficiently reducing the iron oxide raw materials, the consumption rate of the carbon used can be reduced, thereby reducing the CO2 emissions emitted during the ironmaking process.

[0003] Therefore, raw materials are being developed to further improve reduction efficiency. For example, Patent Document 1 proposes a method using carbon-filled pellets, formed by granulating micronized ore with coke, anthracite, or other carbon materials as the core, as sintering raw materials, ultimately obtaining carbon-filled sinter. Patent Document 2 proposes a carbon-filled ore formed by filling nano-sized pores in porous ore with carbon materials such as tar. Furthermore, Patent Document 3 proposes a non-calcined carbon-filled ore obtained by adding a binder to iron oxide raw materials and micronized carbon materials such as coke powder or coke ash. Furthermore, Patent Document 4 proposes a carbon-filled ore with a coal core and a specified coating thickness, and a reduction method thereof. [Prior Art Documents] [Patent Documents]

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-007576; Patent Document 2: Japanese Patent Application Publication No. 2019-007036; Patent Document 3: Japanese Patent Application Publication No. 2015-137379; Patent Document 4: Japanese Patent Application Publication No. 2015-193906 [Summary of the Invention]

[0005] (Problem to be solved by the invention) The technologies disclosed in the above-mentioned Patent Documents 1 to 4 are all related to the development of carbon materials containing ore, but they all use coal or coke, tar, etc. as carbon materials, and cannot fundamentally change the reduction behavior of existing carbon materials containing ore.

[0006] This invention was made in view of the above circumstances, and its object is to provide a method for manufacturing carbon-filled ore, which can change the reduction behavior of existing carbon-filled ore and obtain carbon-filled ore exhibiting higher reducibility. (Technical means to solve the problem)

[0007] The inventors have studied the carbon material contained in carbon-filled ore. As a result, they found that by changing the carbon material to fibrous carbon precipitated from porous iron by carbonization treatment with a gas containing CO and H2, the reduction efficiency can be significantly improved, thus conceiving the method for manufacturing carbon-filled ore according to the present invention.

[0008] The method for manufacturing carbon material containing ore according to the present invention is a method for manufacturing carbon material containing ore for molten iron manufacturing used in the ironmaking industry. The method is characterized in that: fibrous carbon precipitated by carbonizing porous iron with a gas containing CO and H2 is used as the carbon source.

[0009] Furthermore, in the method for manufacturing the carbon material containing ore according to the present invention configured as described above, it is considered that using iron carbide (Fe3C) or using iron carbide (Fe3C) plus over-iron carbide (Fe5C2) as the carbon source would be a better solution. (Comparison with the advantages of prior art)

[0010] According to the method for manufacturing carbon material containing ore according to the present invention, by changing the carbon material to fibrous carbon precipitated by carbonizing porous iron with a gas containing CO and H2, the reduction efficiency can be significantly improved.

Implementation Method

[0012] Hereinafter, specific embodiments of the present invention will be described. Furthermore, the following embodiments are examples of apparatuses or methods for embodying the technical concept of the present invention, and are not intended to be specifically limited to the following content. That is, the technical concept of the present invention can be modified in various ways within the scope of the technology described in the claims.

[0013] Generally, iron oxide raw materials and carbon materials are charged into the reduction furnace as separate raw materials. However, as shown in the aforementioned patent documents, the industry is researching carbon-in-charge ore, that is, accelerating the reaction by bringing the iron oxide raw materials and carbon materials into close proximity from a more microscopic perspective. Carbon-in-charge ore is formed by mixing iron oxide raw materials and carbon materials and then lumping them together using a certain method. In this case, by bringing the physical distance between the iron oxide raw materials and carbon materials closer, a chain reaction of reduction reaction (FeOx + CO → FeOx - 1 + CO2) and solution loss reaction (CO2 + C → 2CO) (coupling reaction) occurs. Therefore, even under the same reduction conditions, a higher reduction rate can be obtained. The carbon materials used in existing carbon-in-charge ore are coal or coke or pulverized coal made from it, or tar, and biomass other than coal. Therefore, it cannot be expected that the reduction efficiency can be improved more than that achieved by using a coupling reaction of basic reduction reaction and solution loss reaction.

[0014] Here, the inventors have discovered that by changing the carbon material used in carbon-filled ore to fibrous carbon precipitated from porous iron through carbonization treatment with a gas containing CO and H2, a higher reduction efficiency can be obtained. This fibrous carbon can be obtained by contacting porous iron with a gas containing CO and H2 at a predetermined temperature. Through the contact between porous iron and CO+H2, iron carbide (Fe3C) or iron carbide (Fe3C) plus overcarbide (Fe5C2) is first generated. Subsequently, when the carbon concentration of iron carbide and overcarbide becomes saturated, a portion of the iron carbide and overcarbide transforms into metallic iron, and fibrous carbon begins to grow from this point, thereby obtaining fibrous carbon (DCW) with tiny iron particles at its ends. Since this fibrous carbon uses the tiny iron particles at its ends as a catalyst to accelerate the solution loss reaction, it can be used as a carbon material in carbon-filled ore to achieve a higher reduction rate.

[0015] Figure 1 is a diagram showing one embodiment of the vertical electric furnace testing apparatus used in the embodiments of the present invention. In the embodiment shown in Figure 1, the electric furnace testing apparatus 1 includes: a molten silicon dioxide tube 2, a partition plate 3, an alumina tube 4, an alumina ball 5, a sample 6, and a lamp 7. Furthermore, in the electric furnace testing apparatus 1, a measuring thermocouple 8 is arranged at the upper part, and a control thermocouple 9 is arranged at the lower part. In this configuration of the electric furnace testing apparatus 1, Ar and N2 are supplied to the sample 6 from the lower part via an MFC (mass flow controller), and gases are released to the outside from the upper part via a pump, a tar filter, and a micro gas chromatograph. [Example]

[0016] <Sample Preparation> First, the method for preparing the sample used in the test will be explained. As an iron catalyst, a sample obtained by cutting fibrous iron with a porosity of 94.6% into cylindrical blocks is prepared. The sample is then brought into contact with a predetermined gas at a predetermined temperature to perform a carbonization treatment. The carbonization conditions are shown in Table 1 below, and Figure 2 shows the backscattered electron images (BSE images) of the samples after carbonization treatment under each condition.

[0017] [Table 1] carbonization conditions (Gas type / Time / Temperature) Precipitated carbon forms Iron carbide (Fe3C) Overcarbide (Fe5C2) Scaly carbon fibrous carbon DCI1 CO / 120 min / 600℃ ○ - ○ - DCI2 CO-CO2-H2 / 120 min / 600℃ ○ ○ ○ ○ DCI3 CO-CO2-H2 / 120 min / 650℃ ○ - ○ ○

[0018] Based on the results in Table 1 and Figure 2, the following can be observed: In DCI1, scaly carbon precipitated on the surface of fibrous iron carbide (Fe3C). In DCI2, in addition to fibrous iron carbide (Fe3C), fibrous overcarbide (Fe5C2) was also formed, and fibrous carbon (DCW) was also formed. In DCI3, fibrous iron carbide (Fe3C) was formed, and fibrous carbon (DCW) was also formed.

[0019] Regarding these DCI2 and DCI3, samples of separated iron carbide (Fe3C), supercarbide (Fe5C2), and precipitated fibrous carbon (DCW) are prepared for use in carbon materials containing ore. Next, three types of fibrous carbon (DCW) with different carbon concentrations are prepared. Details are shown in Table 2 below.

[0020] [Table 2] carbonization conditions (Gas type / Time / Temperature) C concentration (%) DCW1 CO-CO2-H2 / 120 min / 600℃ 70.9 DCW2 CO-CO2-H2 / 100 min / 600℃ 59.5 DCW3 CO-CO2-H2 / 80 min / 600℃ 48.5

[0021] Using DCI1~3 and DCW1~3, hematite reagents were mixed under the conditions shown in Table 3 below so that all levels were C / O 1.0 and C / Fe 0.64, carbon-filled ore was prepared.

[0022] [Table 3] Fe2O3 DCI1 DCI2 (After separation) DCI3 (After separation) fibrous carbon DCW1 DCW2 DCW3 Carbon concentration (%) - 19.3 8.53 7.87 70.9 59.5 48.5 DCIC1 (Comparative Example) 0.46 0.54 - - - - - DCIC2 (Example) 0.46 - 0.45 - 0.09 - - DCIC3 (Example) 0.46 - 0.43 - - 0.11 - DCIC4 (Example) 0.46 - - 0.42 - 0.12 - DCIC5 (Example) 0.46 - 0.39 - - - 0.15 DCIC6 (Example) 0.46 - - 0.39 - - 0.15

[0023] <Reduction Test> Reduction tests were conducted on the prepared carbon material samples containing ore using the vertical electric furnace test apparatus shown in Figure 1. The samples were heated to 1300°C at a rate of 10°C / min in an Ar-5%N2 atmosphere, and the reduction rate was calculated based on the CO and CO2 in the exhaust gas. Figure 3 shows the reduction curves for each sample, illustrating the relationship between temperature and reduction rate. The results in Figure 3 show that DCIC5 and 6 started reduction from low temperatures, followed by DCIC2-4, with DCIC1 being the slowest. The reduction curves were differentiated until almost all the iron oxide was reduced to metallic iron, and a graph showing the relationship between the maximum reduction rate and the amount of fibrous carbon (DCW) was plotted, as shown in Figure 4. The higher the proportion of fibrous carbon (DCW), the greater the tendency for the maximum reduction rate.

[0024] Furthermore, Figure 5 shows photographs of the appearance of the ore-filled carbon materials at 1300°C. DCIC1, which does not contain fibrous carbon (DCW), is not completely melted, indicating the efflux of small iron particles from the surface. DCIC3-6, containing a large amount of fibrous carbon (DCW), are completely melted and spherical, suggesting that the presence of DCW promotes carburizing. On the other hand, no difference is observed between DCIC3, 4 and DCIC5, 6, suggesting that the presence or absence of supercarburized iron has a relatively small impact on the melting behavior. (Industrial Applicability)

[0025] According to the present invention, by changing the carbon material to fibrous carbon precipitated from porous iron by carbonization treatment with a gas containing CO and H2, the reduction efficiency can be dramatically improved. As a result, carbon-filled ore exhibiting higher reducibility can be obtained. [Simplified Explanation of the Diagram]

[0011] Figure 1 is a diagram showing one embodiment of the vertical electric furnace test apparatus used in the embodiments of the present invention. Figure 2 is a diagram showing backscattered electron images (BSE images) of samples after carbonization treatment under various conditions. Figure 3 is a graph showing the relationship between temperature and reduction rate for each sample. Figure 4 is a graph showing the relationship between the maximum reduction rate and the amount of fibrous carbon (DCW) for each sample. Figure 5 is a photograph showing the appearance of the ore-filled carbon material at 1300°C.

Claims

1. A method for manufacturing carbon material containing ore, which is a method for manufacturing carbon material containing ore for molten iron manufacturing used in the ironmaking industry, characterized in that fibrous carbon precipitated by carbonizing porous iron with a gas containing CO and H2 is used as the carbon source.

2. The method for manufacturing carbon material containing ore as described in claim 1, wherein, Use iron carbide (Fe3C) or iron carbide (Fe3C) with added iron carbide (Fe5C2) as the carbon source.

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