Method for producing carbon composite ore

Abstract

The present invention proposes a method for producing a carbon composite ore whereby it is possible to obtain a carbon composite ore that changes the reduction behavior of an existing carbon composite ore and exhibits higher reductive properties. This method for producing a carbon composite ore is for producing a carbon composite ore for use in the production of molten iron used in the iron industry. Fibrous carbon precipitated by carbonization treatment of porous iron by means of a gas containing CO and H2 is used as a carbon source. As a preferred embodiment of the method for producing a carbon composite ore, iron carbide (Fe3C) or iron carbide (Fe3C) and edscottite (Fe5C2) are used as the carbon source.

Description

Carbon composite ore manufacturing method

[0001] The present invention relates to a method for producing carbonaceous ore for producing molten iron used in the steel industry.

[0002] In the steel industry, CO ２ Reducing emissions is an urgent issue. The process that produces the largest amount of CO2 emissions is the pig iron making process, in which raw materials are melted and reduced. In the reduction furnace, iron oxide raw materials (sintered ore, lump ore, pellets, etc.) and carbonaceous material (C) are charged, and CO2 generated by gasification of the carbonaceous material reduces FeO Ｘ +CO → FeO Ｘ－１ +CO ２ As shown in the overall reaction rate equation, reduction using carbon (C) occurs. However, not all of the charged carbonaceous material is used for reduction. By efficiently reducing the iron oxide raw material, the unit consumption of carbonaceous material used can be reduced, and the CO2 emitted from the ironmaking process can be reduced. ２ Emissions can be reduced.

[0003] For this reason, raw materials have been developed to further improve reduction efficiency. For example, Patent Document 1 proposes a method of using carbonaceous composite pellets, which are granulated with fine ore using a carbonaceous material such as coke or anthracite as a nucleus, as a sintering raw material, to ultimately obtain carbonaceous composite sintered ore. Patent Document 2 proposes a carbonaceous composite ore in which nanometer-level pores in porous ore are filled with a carbonaceous material such as tar. Patent Document 3 proposes a non-calcined carbonaceous composite ore produced by adding a binder to an iron oxide raw material and a finely powdered carbonaceous material such as coke powder or coke dust. Patent Document 4 also proposes a carbonaceous composite ore in which the thickness of a coating layer is specified using coal as a nucleus, and a reduction method thereof.

[0004] JP 2020-007576 A JP 2019-007036 A JP 2015-137379 A JP 2015-193906 A

[0005] The techniques disclosed in the above-mentioned Patent Documents 1 to 4 are all techniques related to the development of carbonaceous ore composites, but they use coal, coke, tar, or the like as the carbonaceous material, and are not capable of fundamentally changing the reduction behavior of existing carbonaceous ore composites.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to propose a method for producing carbonaceous ore, which can change the reduction behavior of existing carbonaceous ore and obtain carbonaceous ore that exhibits higher reducibility.

[0007] The inventors have investigated the carbonaceous materials contained in carbonaceous composite ores. As a result, it was found that the carbonaceous materials were mixed with porous iron to form CO and H ２ The inventors have found that the reduction efficiency can be dramatically improved by changing the carbon material into fibrous carbon precipitated by carbonization treatment with a gas containing carbon, and have conceived the method for producing carbon composite ore according to the present invention.

[0008] The method for producing carbonaceous ore of the present invention is a method for producing carbonaceous ore for producing molten iron used in the steel industry, and comprises adding CO and H to porous iron as a carbon source. ２ The carbon fiber is characterized by using fibrous carbon precipitated by carbonization treatment using a gas containing

[0009] In the method for producing carbonaceous ore according to the present invention, iron carbide (Fe ３ C) or iron carbide (Fe ３ C) plus iron percarbide (Fe ５ C ２ ) is considered to be a more preferable solution.

[0010] According to the method for producing carbonaceous ore of the present invention, the carbonaceous material is mixed with the porous iron and CO and H ２ By changing the carbon to fibrous carbon precipitated by carbonization treatment using a gas containing , the reduction efficiency can be dramatically improved.

[0011] Fig. 1 is a diagram showing one embodiment of a vertical electric furnace test apparatus used in the examples of the present invention; Fig. 2 is a diagram showing backscattered electron images (BSE images) of samples after carbonization treatment under each condition; Fig. 3 is a graph showing the relationship between temperature and reduction rate for each sample; Fig. 4 is a graph showing the relationship between maximum reduction rate and amount of fibrous carbon (DCW) for each sample; Fig. 5 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 6 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 7 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 8 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 9 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 10 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 11 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 12 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 13 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 14 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 15 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 16 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 17 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 18 is a diagram showing external photographs of each carbon composite ore when it reached 1300°C; Fig. 19 is a

[0012] The following describes in detail the embodiments of the present invention. Note that the following embodiments are intended to exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to that described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope defined in the claims.

[0013] Generally, the iron oxide raw material and the carbonaceous material are treated as separate raw materials and charged into a reduction furnace. However, as shown in the above-mentioned patent documents, carbonaceous ore is being studied to accelerate the reaction by placing the iron oxide raw material and the carbonaceous material close to each other from a more microscopic point of view. Carbonaceous ore is made by mixing the iron oxide raw material and the carbonaceous material and agglomerating them in some way. In this case, by physically bringing the iron oxide raw material and the carbonaceous material close to each other, the reduction reaction (FeO Ｘ +CO → FeO Ｘ－１ +CO ２ ) and solution loss reaction (CO ２ + C → 2CO) occurs in a chain reaction (coupling reaction), which allows a high reduction rate to be achieved even under the same reduction conditions. The carbonaceous materials used in existing carbonaceous composite ores are coal, coke made from coal, its dust, tar, or biomass other than coal. Therefore, it is not possible to expect any effect beyond the improvement in reduction efficiency achieved by the coupling reaction of the basic reduction reaction and the solution loss reaction.

[0014] Here, the carbon material used in the carbonaceous composite ore is mixed with porous iron and CO and H ２ The inventors have found that a high reduction efficiency can be obtained by changing the carbon fiber to one that is deposited by carbonization treatment with a gas containing CO and H. This fibrous carbon is produced by heating porous iron to a predetermined temperature. ２It can be obtained by contacting porous iron with a gas containing CO + H ２ When the two materials come into contact, iron carbide (Fe ３ C), or iron carbide (Fe ３ C) plus iron percarbide (Fe ５ C ２ ) is produced. After that, when the carbon concentration of the iron carbide and iron overcarbonate becomes saturated, a part of the iron carbide and iron overcarbonate changes to metallic iron, and fibrous carbon grows from this starting point, thereby obtaining fibrous carbon (DCW) having fine iron particles at its end. This fibrous carbon accelerates the solution loss reaction using the fine iron particles at the end as a catalyst, so when used as a carbon material in carbon composite ore, a high reduction rate can be obtained.

[0015] Fig. 1 is a diagram showing one embodiment of a vertical electric furnace test apparatus used in the examples of the present invention. In the embodiment shown in Fig. 1, the electric furnace test apparatus 1 is composed of a fused silica tube 2, a spacer 3, an alumina tube 4, an alumina ball 5, a sample 6, and a lamp 7. In the electric furnace test apparatus 1, a measurement thermocouple 8 is disposed at the top, and a control thermocouple 9 is disposed at the bottom. In the electric furnace test apparatus 1 configured as above, Ar and N are introduced from the bottom. ２ The gas is supplied to the sample 6 via an MFC (mass flow controller), and the gas is released to the outside from the top via a pump, a tar filter, and a micro gas chromatograph.

[0016] <Sample Preparation> First, the method for preparing the samples used in the test will be described. A test piece was prepared by cutting fibrous iron with a porosity of 94.6% into a cylindrical block as an iron catalyst. A carbonization treatment was carried out by bringing this test piece into contact with a predetermined gas at a predetermined temperature. The carbonization conditions are shown in Table 1 below, and backscattered electron images (BSE images) of the carbonized samples under each condition are shown in Figure 2.

[0017]

[0018] From the results in Table 1 and Figure 2, the following was found: In DCI1, fibrous iron carbide (Fe ３In DCI2, fibrous iron carbide (Fe ３ C), and fibrous iron percarbide (Fe ５ C ２ ) and fibrous carbon (DCW) were produced. In DCI3, fibrous iron carbide (Fe ３ C) was produced, and fibrous carbon (DCW) was produced.

[0019] DCI2 and DCI3 are used for carbon composite ore, so iron carbide (Fe ３ C), iron percarbide (Fe ５ C ２ The carbon fiber (DCW) was separated from the precipitated fibrous carbon (DCW) to prepare a sample. Next, three types of fibrous carbon (DCW) with different carbon concentrations were prepared. Details are shown in Table 2 below.

[0020]

[0021] Using these DCI1 to 3 and DCW1 to 3, carbonaceous ore was prepared by mixing a hematite reagent under the conditions shown in Table 3 below so that C / O was 1.0 and C / Fe was 0.64 at all levels.

[0022]

[0023] <Reduction Test> The prepared carbonaceous composite ore samples were subjected to a reduction test using a vertical electric furnace test device shown in Figure 1. ２ The temperature was increased to 1300°C at a rate of 10°C / min in an atmosphere, and CO and CO in the exhaust gas were removed. ２ The reduction rate was calculated from the above. Figure 3 shows the reduction curves indicating the relationship between the temperature and the reduction rate for each sample. In Figure 3, DCIC5 and 6 started to reduce at a low temperature, followed by DCIC2 to 4, and DCIC1 was the slowest. The reduction curves were differentiated until almost all of the iron oxide was reduced to metallic iron, and the relationship between the maximum reduction rate and the amount of fibrous carbon (DCW) at that time was plotted in Figure 4. There was a tendency for the maximum reduction rate to increase as the proportion of fibrous carbon (DCW) increased.

[0024] Figure 5 shows photographs of the appearance of each carbonaceous ore composite when it reached 1,300°C. DCIC1, which does not contain fibrous carbon (DCW), did not melt completely, and exhibited behavior in which small iron particles oozed from the surface. DCICs 3 to 6, which contain a large amount of fibrous carbon (DCW), melted entirely and exhibited a spherical shape, suggesting that the presence of DCW promotes carburization. On the other hand, no difference was observed between DCICs 3 and 4 and DCICs 5 and 6, suggesting that the presence or absence of over-iron carbide has little effect on melting behavior.

[0025] According to the present invention, carbon material is mixed with porous iron to form CO and H ２ By changing the carbon to fibrous carbon precipitated by carbonization treatment with a gas containing , the reduction efficiency can be dramatically improved. As a result, carbon composite ore with higher reducibility can be obtained.

[0026] REFERENCE SIGNS LIST 1 Electric furnace test device 2 Fused silica tube 3 Spacer 4 Alumina tube 5 Alumina ball 6 Sample 7 Lamp 8 Measurement thermocouple 9 Control thermocouple

Claims

1. A method for producing carbonaceous ore for molten iron production used in the steel industry, in which CO and H are added to porous iron as a carbon source. ２ 1. A method for producing carbonaceous ore containing carbon, comprising the step of: using fibrous carbon precipitated by carbonization treatment with a gas containing carbon; 2. The method for producing carbonaceous ore according to claim 1, wherein iron carbide (Fe ３ C) or iron carbide (Fe ３ C) plus iron percarbide (Fe ５ C ２ ) is used.

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