Method for producing carbonaceous material-charged ore

Abstract

To provide a method for producing a carbonaceous material-charged ore that enables alteration of reduction behavior of an existing carbonaceous material-charged ore and exhibits higher reducibility.SOLUTION: A method for producing a carbonaceous material-charged ore according to the present invention is a method for producing a carbonaceous material-charged ore for molten iron production used in the steel industry, wherein fibrous carbon deposited on porous iron by a carbonization treatment using a gas containing CO and H2 is used as a carbon source. In a preferred embodiment of the method for producing a carbonaceous material-charged ore according to the present invention, iron carbide (Fe3C) or iron carbide (Fe3C) as well as edscottite (Fe5C2) is used as the carbon source.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Reducing CO2 emissions is an urgent issue in the steel industry. The pig iron making process is considered to have particularly large emissions, and is the process of producing pig iron by melting and reducing raw materials. In the reduction furnace, iron oxide raw materials (sinter, lump ore, pellets, etc.) and carbonaceous material (C) are charged, and the CO generated by gasification of the carbonaceous material reduces FeO X +CO → FeO X-1 As shown in the overall reaction rate equation for +CO2, reduction using carbon (C) occurs. However, not all of the charged carbonaceous material is used for reduction, and by efficiently reducing the iron oxide raw material, it is possible to reduce the specific consumption of carbonaceous material, which in turn reduces the amount of CO2 emitted from the ironmaking process.

[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. [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 Laid-Open No. 2015-137379 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-193906 Summary of the Invention [Problem to be solved by the invention]

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

[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. [Means for solving the problem]

[0007] The inventors have studied the carbonaceous material contained in carbonaceous composite ores, and as a result, have found that the reduction efficiency can be dramatically improved by changing the carbonaceous material to fibrous carbon precipitated by carbonizing porous iron with a gas containing CO and H2, and have conceived the method for producing carbonaceous composite ores 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 is characterized in that fibrous carbon precipitated by carbonization treatment of porous iron with a gas containing CO and H is used as a carbon source.

[0009] In the method for producing carbonaceous ore of the present invention configured as described above, iron carbide (Fe3C) or iron carbide (Fe3C) and iron percarbide (Fe5C2) are used as the carbon source, This is considered to be a more preferable solution. [Effects of the Invention]

[0010] According to the method for producing carbonaceous ore of the present invention, the reduction efficiency can be dramatically improved by changing the carbonaceous material to fibrous carbon precipitated by carbonizing porous iron with a gas containing CO and H. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an embodiment of a vertical electric furnace test apparatus used in the examples of the present invention. [Figure 2] FIG. 1 shows backscattered electron images (BSE images) of samples after carbonization treatment under each condition. [Figure 3] 1 is a graph showing the relationship between temperature and reduction rate for each sample. [Figure 4] 1 is a graph showing the relationship between the maximum reduction rate and the amount of fibrous carbon (DCW) in each sample. [Figure 5] FIG. 10 is a photograph showing the appearance of each carbon composite ore when it reached 1300°C. DETAILED DESCRIPTION OF THE INVENTION

[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, iron oxide raw material and 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 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 carbonaceous material and agglomerating them in some way. In this case, by physically bringing the iron oxide raw material and carbonaceous material close to each other, the reduction reaction (FeO X +CO → FeO X-1The chain reaction (coupling reaction) of the reduction reaction (CO2 + C → 2CO) and the solution loss reaction (CO2 + C → 2CO) occurs in a chain reaction (coupling reaction), making it possible to obtain a high reduction rate even under the same reduction conditions. The carbonaceous materials used in existing carbonaceous ore composites 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] The inventors discovered that high reduction efficiency can be achieved by replacing the carbonaceous material used in carbonaceous ore with fibrous carbon precipitated by carbonization of porous iron with a gas containing CO and H. This fibrous carbon can be obtained by contacting porous iron with a gas containing CO and H at a predetermined temperature. The contact of porous iron with CO and H initially produces iron carbide (FeC), or iron carbide (FeC) plus iron supercarbide (FeC). Subsequently, when the iron carbide and iron supercarbide are saturated, a portion of them transforms into metallic iron. From this point, fibrous carbon grows, producing fibrous carbon (DCW) with fine iron particles at the edge. This fibrous carbon accelerates the solution loss reaction using the fine iron particles at the edge as a catalyst, enabling high reduction efficiency when used as a carbonaceous material in carbonaceous ore.

[0015] Figure 1 shows one embodiment of a vertical electric furnace test apparatus used in the examples of the present invention. In the embodiment shown in Figure 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 addition, a measurement thermocouple 8 is disposed in the upper part of the electric furnace test apparatus 1, and a control thermocouple 9 is disposed in the lower part. In the electric furnace test apparatus 1 configured as above, Ar and N2 are supplied to the sample 6 from the lower part via an MFC (mass flow controller), and the gas is released to the outside from the upper part via a pump, a tar filter, and a micro gas chromatograph. [Example]

[0016] <Sample preparation> First, we will explain how the samples used in the test were prepared. A test piece was prepared by cutting fibrous iron with a porosity of 94.6% into a cylindrical block to serve as the iron catalyst. This test piece was carbonized by contacting a specified gas at a specified temperature. Table 1 below shows the carbonization conditions, and Figure 2 shows backscattered electron images (BSE images) of the samples after carbonization under each condition.

[0017] [Table 1]

[0018] The results in Table 1 and Figure 2 reveal the following: In DCI1, scale-like carbon precipitated on the surface of fibrous iron carbide (Fe3C). In DCI2, in addition to fibrous iron carbide (Fe3C), fibrous iron percarbide (Fe5C2) was formed, and fibrous carbon (DCW) was also formed. In DCI3, fibrous iron carbide (Fe3C) was formed, and fibrous carbon (DCW) was also formed.

[0019] For DCI2 and DCI3, samples were prepared by separating iron carbide (Fe3C), iron percarbide (Fe5C2), and precipitated fibrous carbon (DCW) for use in carbon composite ore. Next, three types of fibrous carbon (DCW) with different carbon concentrations were prepared. Details are shown in Table 2 below.

[0020] [Table 2]

[0021] Using these DCI1 to 3 and DCW1 to 3, carbon composite ores were 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 for all levels.

[0022] [Table 3]

[0023] <About the reduction test> A reduction test was conducted on the prepared carbon composite ore samples 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 from the CO and CO2 in the exhaust gas. Figure 3 shows the reduction curves for each sample, showing the relationship between temperature and reduction rate. In Figure 3, DCIC5 and 6 began to reduce at low temperatures, followed by DCIC2-4, with DCIC1 being 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) was plotted in Figure 4. The maximum reduction rate tended to increase with the proportion of fibrous carbon (DCW).

[0024] Figure 5 shows photographs of the appearance of each carbon composite ore when it reached 1300°C. DCIC1, which does not contain fibrous carbon (DCW), did not melt completely, and small iron particles appeared to seep out from the surface. DCIC3 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 DCIC3, 4 and DCIC5, 6, suggesting that the presence or absence of over-iron carbide has little effect. [Industrial Applicability]

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

[0026] 1 Electric furnace test equipment 2 fused silica tubes 3 spacers 4 alumina tubes 5 alumina balls 6 Samples 7 Lamp 8 Thermocouples for measurement 9 Control thermocouple

Claims

【Request Item 1】 A method for producing carbonaceous ore for producing molten iron used in the steel industry, comprising adding CO and H 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; 【Request Item 2】 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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