Method for producing coke

Abstract

To provide a method for producing coke that contains solid-state carbon produced of carbon-containing gas, and has a degree of hardness at which the coke is usable even in a blast furnace.SOLUTION: A method for producing coke includes: a carbon generation step of generating solid-state carbon from carbon monoxide or carbon dioxide; a coke generation step of generating coke by using coal and solid-state carbon, where in the case of generating solid-state carbon from carbon dioxide in the carbon generation step, (1) a step of generating carbon monoxide from carbon dioxide and hydrogen by reverse water-gas shift reaction, and a step of generating solid-state carbon from generated carbon monoxide are performed, or (2) a methane generation step of allowing carbon dioxide to react with hydrogen to generate methane, and a methane decomposition step of thermally decomposing methane generated in the methane generation step to generate solid-state carbon are performed.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing coke. [Background technology]

[0002] From the perspective of environmental issues, there is a need to reduce carbon dioxide emissions in processes such as coke production and steelmaking.

[0003] In the steelmaking process, hot air is blown into a blast furnace through a tuyere. This causes the oxygen in the hot air to react with the reducing agents, such as coke and pulverized coal, to produce carbon monoxide and hydrogen gases. These carbon monoxide and hydrogen gases reduce the iron ore charged into the blast furnace. This reduction reaction of the iron ore also produces carbon dioxide. The gas discharged from the blast furnace (by-product gas) contains components such as carbon monoxide, carbon dioxide, and hydrogen. These components contained in the by-product gas may be used as raw materials for producing solid carbon.

[0004] Patent Document 1 discloses a method for producing metals from metal ores in a blast furnace, using coke to produce a reducing gas mixture containing carbon monoxide. In this method, carbon monoxide is converted into a carbonaceous reductant by contacting it with a catalyst, and this carbonaceous reductant is supplied to the blast furnace as a substitute for at least a portion of the coke. The carbonaceous reductant is briquetted. When briquetting the carbonaceous reductant, a coal-derived binder or tar is used as a binder (corresponding to the binder described below).

[0005] Patent Document 2 discloses a solid carbon generating apparatus and a solid carbon generating method. This solid carbon generating apparatus includes a separation facility that separates carbon dioxide gas contained in a generated gas generated in a blast furnace, a reaction facility that heats a fuel gas containing methane gas as a main component using a heating facility and decomposes the methane gas into solid carbon and hydrogen gas, and a generation facility that reacts the carbon dioxide gas separated in the separation facility with the hydrogen gas decomposed in the reaction facility to generate solid carbon and water. A solid carbon generating method is realized by this solid carbon generating apparatus. In this solid carbon generating method, solid carbon is obtained in powder form. The solid carbon is mixed with a binder to form granular pellets (granular solid carbonaceous material), which are then supplied to a blast furnace.

[0006] Patent Document 3 discloses a method for producing solid carbon by reducing carbon oxides. In this production method, the carbon oxides subjected to the reduction reaction are typically either carbon monoxide or carbon dioxide, and the reducing agent subjected to the reduction reaction is typically a hydrocarbon gas or hydrogen.

[0007] Patent Document 4 discloses a method for treating off-gas containing carbon oxides, which includes purifying the off-gas to remove particulate matter, water, undesirable gaseous constituents, and inert gases to produce a dry carbon oxide gas feedstock, and converting at least a portion of the carbon oxides in the dry carbon oxide gas feedstock to solid carbon. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 54-150388 [Patent Document 2] Patent Publication No. 2021-165214 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-57372 [Patent Document 4] Special Publication No. 2015-516361 Summary of the Invention [Problem to be solved by the invention]

[0009] If by-product gases are used more effectively, further reductions in carbon dioxide emissions can be achieved in the steelmaking process. When solid carbon generated from by-product gases is used in a blast furnace in the steelmaking process, for example, as a substitute for coke, methods for supplying the solid carbon into the blast furnace include, for example, blowing it into the blast furnace from the tuyere together with hot air, and charging it into the furnace from the top of the blast furnace. Of these, when blowing solid carbon into the tuyere, the amount of solid carbon blown in is limited. Therefore, if solid carbon can be charged from the top, a large amount of solid carbon can be used. However, when solid carbon is charged into the furnace from the top, like coke generally used in blast furnaces, the solid carbon is required to have a certain size and strength that does not powder in the blast furnace. Therefore, it is required to agglomerate the solid carbon and use it in the blast furnace. In particular, for a relatively large-capacity blast furnace (for example, 1000 m 3 In a blast furnace with an internal volume of 1000 or more, the mass of the contents inside the furnace is large. Therefore, if the strength of the solid carbon agglomerates is low, the agglomerates may break down into powder and scatter inside the furnace, or the particles generated by the powdering may obstruct ventilation inside the furnace, making it impossible to operate the blast furnace.

[0010] In conventional techniques such as those disclosed in Patent Documents 1 and 2, solid carbon is sometimes agglomerated using a binder. However, when agglomerates using a binder are charged into a blast furnace, the binder volatilizes due to the heat inside the blast furnace, and the volatilized components may interfere with the gas recovery process from the blast furnace, or the agglomerates may be pulverized by the heat or impact inside the blast furnace. Therefore, it may not be possible to use such agglomerates in large quantities in a blast furnace. Furthermore, even if agglomerates are formed using a binder, it is not always possible to obtain agglomerates with appropriate strength that will not pulverize in the blast furnace.

[0011] In view of these circumstances, it is desired to provide a method for obtaining agglomerates such as coke containing solid carbon produced from carbon-containing gases such as carbon monoxide and carbon dioxide contained in by-product gases, the agglomerates having a strength sufficient to be usable in a blast furnace.

[0012] The present invention has been made in consideration of the above circumstances, and its object is to provide a method for producing coke containing solid carbon produced from a carbon-containing gas and having a strength sufficient for use in a blast furnace. [Means for solving the problem]

[0013] In order to achieve the above object, the method for producing coke according to the present invention is as follows.

[0014] [1] A carbon production step of producing solid carbon from carbon monoxide or carbon dioxide; a coke production step of producing coke using coal and the solid carbon, When solid carbon is produced from carbon dioxide in the carbon production step, (1) producing the solid carbon from carbon dioxide and hydrogen by a reverse water gasification reaction; (2) performing a step of producing carbon monoxide from carbon dioxide and hydrogen by a reverse water gas shift reaction, and a step of producing the solid carbon from the produced carbon monoxide; or (3) A method for producing coke, comprising a methane production step of reacting carbon dioxide with hydrogen to produce methane, and a methane decomposition step of thermally decomposing the methane produced in the methane production step to produce the solid carbon.

[0015] [2] The method for producing coke according to the above [1], wherein the carbon production step comprises reacting carbon monoxide with hydrogen to produce the solid carbon.

[0016] [3] In the carbon production step, a methane production step in which carbon dioxide and hydrogen are reacted to produce methane; A method for producing coke according to the above [1] or [2], which comprises a methane decomposition step in which the methane produced in the methane production step is thermally decomposed to produce the solid carbon.

[0017] [4] The method for producing coke according to any one of [1] to [3] above, wherein the iron content of the solid carbon is 10 mass % or less. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a method for producing coke containing solid carbon produced from a carbon-containing gas and having a strength sufficient for use in a blast furnace. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a reactor for producing solid carbon from carbon monoxide. [Figure 2] 1 is a photograph of sinter after producing solid carbon 2. [Figure 3] This is a photograph of solid carbon 2 separated and recovered from sintered ore. [Figure 4] FIG. 1 is a schematic diagram of an electric furnace for producing solid carbon from methane. [Figure 5] FIG. 1 is a schematic diagram of a furnace for producing solid carbon from methane. [Figure 6] TEM image of solid carbon 1. [Figure 7] TEM image of solid carbon 3. [Figure 8] TEM image of solid carbon-4. DETAILED DESCRIPTION OF THE INVENTION

[0020] A method for producing coke according to an embodiment of the present invention will be described with reference to the drawings.

[0021] An outline of the coke manufacturing method according to this embodiment will be described.

[0022] The coke production method according to this embodiment includes a carbon production step of producing solid carbon from carbon monoxide (CO) or carbon dioxide (CO2), and a coke production step of producing coke using coal and the solid carbon.

[0023] According to the coke manufacturing method of this embodiment, it is possible to manufacture coke that contains solid carbon manufactured from a carbon-containing gas and has a strength sufficient for use in a blast furnace.

[0024] The coke manufacturing method according to this embodiment will be described in detail below.

[0025] The carbon production process is a process for producing solid carbon from carbon monoxide or carbon dioxide. In other words, the carbon production process is a process for producing solid carbon using carbon monoxide or carbon dioxide as a raw material. The carbon monoxide or carbon dioxide may be contained in a by-product gas of a blast furnace. The reaction (chemical reaction) for producing solid carbon from carbon monoxide or carbon dioxide is not particularly limited. In the following description, carbon monoxide and carbon dioxide are gaseous.

[0026] In the carbon production step, carbon monoxide may be reacted to produce solid carbon. The temperature at which the following reaction occurs is the temperature at which the Gibbs free energy of the reaction becomes negative, and may vary depending on the ambient conditions.

[0027] In the carbon production step, when carbon monoxide is reacted to produce solid carbon, the solid carbon may be produced by the Boudouard reaction shown in the following reaction formula (1). The Boudouard reaction shown in reaction formula (1) can produce solid carbon from carbon monoxide at approximately 700°C or less.

[0028] 2CO → C + CO2 (1)

[0029] In the carbon production step, when carbon monoxide is reacted to produce solid carbon, the solid carbon may be produced by the decomposition reaction shown in the following reaction formula (2): The decomposition reaction shown in reaction formula (2) makes it possible to produce solid carbon from carbon monoxide under a low oxygen partial pressure.

[0030] 2CO → 2C + O2 (2)

[0031] In the carbon production step, carbon monoxide and hydrogen may be reacted to produce solid carbon. In the following description, hydrogen is in gaseous form.

[0032] In the carbon production step, when carbon monoxide and hydrogen are reacted to produce solid carbon, the solid carbon may be produced by the reverse water-gasification reaction shown in the following reaction formula (3). The reverse water-gasification reaction shown in reaction formula (3) can produce solid carbon from carbon monoxide at approximately 650°C or lower.

[0033] CO+H2→C+H2O (3)

[0034] In the carbon production step, carbon dioxide and hydrogen may be reacted to produce solid carbon.

[0035] In the carbon production step, when carbon dioxide and hydrogen are reacted to produce solid carbon, the solid carbon may be produced by the reverse water-gasification reaction shown in the following reaction formula (4). The reverse water-gasification reaction shown in reaction formula (4) can produce solid carbon from carbon dioxide at approximately 650°C or lower.

[0036] CO2 + 2H2 → C + 2H2O (4)

[0037] When carbon dioxide and hydrogen are reacted to produce solid carbon in the carbon production step, carbon monoxide may first be produced from carbon dioxide and hydrogen by the reverse water gas shift reaction shown in the following reaction formula (5), and then solid carbon may be produced by the reaction shown in the above reaction formula (1) or (2). The reverse water gas shift reaction shown in reaction formula (5) can produce carbon monoxide from carbon dioxide at approximately 850°C or higher.

[0038] CO2 + H2 → CO + H2O (5)

[0039] In the carbon production step, when carbon dioxide is reacted to produce solid carbon, the solid carbon may be produced by the decomposition reaction shown in the following reaction formula (6): The decomposition reaction shown in reaction formula (6) makes it possible to produce solid carbon from carbon dioxide under a low oxygen partial pressure.

[0040] CO2 → C + O2 (6)

[0041] In addition, in the carbon production step, solid carbon may be produced by carrying out a methane production step in which carbon monoxide or carbon dioxide is reacted with hydrogen to produce methane (CH4), and then carrying out a methane decomposition step in which the methane produced in the methane production step is thermally decomposed to produce solid carbon. Note that in the following description, methane is in gaseous form.

[0042] In the methane production step, methane may be produced from carbon monoxide and hydrogen by the methanation reaction shown in the following reaction formula (7): The methanation reaction shown in reaction formula (7) can produce methane from carbon monoxide at approximately 650°C or lower.

[0043] CO + 3H2 → CH4 + H2O (7)

[0044] In the methane production step, methane may be produced from carbon dioxide and hydrogen by the methanation reaction shown in the following reaction formula (8): The methanation reaction shown in reaction formula (8) can produce methane from carbon dioxide at approximately 600°C or lower.

[0045] CO2 + 4H2 → CH4 + 2H2O (8)

[0046] In the methane decomposition step, solid carbon may be produced from methane by the thermal decomposition reaction shown in the following reaction formula (9): The thermal decomposition reaction shown in reaction formula (9) can produce solid carbon from methane in air at about 500°C or higher.

[0047] CH4 → C + 2H2 (9)

[0048] In the carbon production step, a gas containing two or more of carbon monoxide, carbon dioxide, and methane may be used. Hereinafter, carbon monoxide, carbon dioxide, and methane may be collectively referred to as the raw material gas.

[0049] In the carbon production step, a mixed gas in which carbon monoxide, carbon dioxide, and methane are mixed with hydrogen or nitrogen (each in a gaseous state) may be used.

[0050] In the carbon production process, it is preferable to produce methane through the methanation reaction shown in reaction formula (8) and then produce carbon through the thermal decomposition reaction shown in reaction formula (9). For example, the reaction rate of the reverse water-gasification reaction shown in reaction formula (4) is not high, and therefore the reaction rate may be low depending on the operating conditions. However, the reaction rate of the methanation reaction shown in reaction formula (8) is higher than that of the reverse water-gasification reaction shown in reaction formula (4), and the reaction rate of the thermal decomposition reaction shown in reaction formula (9) is high, generally close to 100%. Therefore, in the carbon production process, it is preferable to produce methane through the methanation reaction shown in reaction formula (8) and then produce carbon through the thermal decomposition reaction shown in reaction formula (9).

[0051] In the carbon production step, it is preferable to use a catalyst, and it is preferable to use a catalyst containing iron, which may promote carbon production.

[0052] In the Boudouard reaction shown in reaction formula (1), it is preferable to use a catalyst containing iron, which accelerates the reaction.

[0053] Similarly, in the thermal decomposition reaction shown in reaction formula (9), it is preferable to use a catalyst containing iron, as this accelerates the reaction.

[0054] Similarly, in the reverse water gas shift reaction shown in reaction formula (5), it is preferable to use a catalyst containing iron, as this accelerates the reaction.

[0055] The type of iron-containing catalyst is not particularly limited. Examples of iron-containing catalysts include metallic iron, iron oxide, and iron-containing compounds. It is more preferable that the iron-containing catalyst contains metallic iron or iron oxide with silicon or sulfur. Specifically, for example, sintered ore, direct-reduced iron, or iron ore pellets may be charged into a reactor, and the iron or iron oxide contained in the sintered ore, direct-reduced iron, or iron ore pellets may be used as the catalyst. When using an iron-containing catalyst, carbon in the gas may dissolve in the catalyst, resulting in precipitation of the dissolved carbon. Specifically, carbon from the reactants, such as those represented by reaction formulas (1) to (4), (6), and (9), dissolves in the catalyst, and solid carbon is produced as the reaction progresses. Furthermore, when using a catalyst, hydrogen is preferred in reaction systems where hydrogen comes into contact with the catalyst because it prevents deactivation of the catalyst surface.

[0056] When carrying out the thermal decomposition reaction shown in reaction formula (9), alumina may be charged into the reactor. By charging alumina, the solid surface area increases due to heterogeneous nucleation, which is expected to promote carbon deposition and to have the effect of uniforming the temperature due to the use of alumina with a high heat capacity, thereby improving the yield.

[0057] The solid carbon produced in the carbon production step may be a powdery or granular carbon-containing material containing solid carbon. In the following description, this will be simply referred to as solid carbon, including cases where the material is a carbon-containing material.

[0058] The iron content of the solid carbon is preferably 50% by mass or less. The iron content of the solid carbon is more preferably 10% by mass or less. The solid carbon may contain, for example, an iron component as a catalyst used in the production process. However, it is not essential that the solid carbon contain iron.

[0059] Coke may be produced by carbonizing green pellets formed by mixing coal with solid carbon produced using carbon monoxide or carbon dioxide as a raw material as described above.

[0060] The solid carbon used in the green pellets may be any of solid carbon produced from carbon monoxide, solid carbon produced from carbon dioxide, and solid carbon produced via methane, or a mixture of these may be used. [Example]

[0061] The coke production method according to the present embodiment will be described below based on examples. However, the coke production method according to the present embodiment is not limited to the examples described below.

[0062] We will explain how to produce solid carbon used in coke production. The solid carbon used was produced by reducing carbon monoxide (CO) with hydrogen (H2), and by decomposing methane (CH4) produced from carbon dioxide (CO2).

[0063] First, an example of producing solid carbon by reduction of carbon monoxide will be described.

[0064] (Production of Solid Carbon 1 and 2) Solid carbon was produced from carbon monoxide by the reverse water gasification reaction shown in reaction formula (3) above, using a vertical reactor 100, the schematic diagram of which is shown in Figure 1, as follows. The reactor 100 is equipped with a cylindrical furnace tube 10 having an inner diameter of 80 mm, and a heater 19 for heating the furnace tube 10, which is arranged so as to surround the furnace tube 10. The furnace tube 10 is arranged with the axial direction of the cylinder aligned vertically.

[0065] First, an alumina support 12, alumina balls 14, and sintered ore 16 as a catalyst were loaded into the furnace tube 10 in this order. The alumina balls 14 and sintered ore 16 were each piled up in layers inside the furnace. The layer of sintered ore 16 was placed on top of the layer of alumina balls 14. A mixed gas containing carbon monoxide, hydrogen, and nitrogen in volume ratios of 31%, 19%, and 50%, respectively, was then supplied as a source gas into the furnace of the furnace tube 10 via a gas inlet pipe 18 located at the bottom of the furnace tube 10. Exhaust gas containing unreacted carbon monoxide, hydrogen, water vapor, and nitrogen was vented to the outside of the system from an opening at the top end of the furnace tube 10.

[0066] The temperature inside the furnace was set to 550° C. or 800° C. by adjusting the output of the heater 19. The temperature inside the furnace is the temperature measured by a thermocouple 15 inserted into the layer of sintered ore 16.

[0067] The gas flow rate of the mixed gas was 17 L / min (value converted to 0°C and 1 atmosphere). The mixed gas was continuously supplied for 3 hours, and soot-like solid carbon was precipitated on the surface of the sintered ore 16. Hereinafter, the carbon precipitated at 550°C will be referred to as solid carbon 1, and the carbon precipitated at 800°C will be referred to as solid carbon 2.

[0068] The solid carbon was then recovered from the reactor 100 together with the sintered ore 16, and separated into the sintered ore 16 and the solid carbon by sieving with a sieve having an opening of 125 μm, and solid carbon 1 and solid carbon 2 were recovered.

[0069] Of the sintered ore 16 in which solid carbon 2 was precipitated (adhered) to the surface, 1.5 mass% was solid carbon. Table 1 shows the results of the component analysis of solid carbon 2. T.Fe (total iron) is a value determined based on the regulations of JIS M 8212. FeO (iron oxide) and M.Fe (metallic iron) are values ​​determined based on the regulations of JIS M 8213. C (carbon) is a value determined by organic element analysis.

[0070] [Table 1]

[0071] Figure 2 shows a photograph of the sintered ore after solid carbon 2 was produced using a mixed gas at 800°C. Figure 3 shows a photograph of the solid carbon 2 separated and recovered from the sintered ore.

[0072] As shown in Figure 3, the solid carbon 2 was visually observed to be in the form of an agglomerated powder. The cumulative 10% diameter, cumulative 50% diameter (median diameter), and cumulative 90% diameter of the solid carbon 2 shown in Figure 3 were 2.1 μm, 6.6 μm, and 14.8 μm, respectively. The cumulative 10% diameter, cumulative 50% diameter, and cumulative 90% diameter are number-based values ​​measured by a laser diffraction / scattering particle size distribution measurement method. Thus, 90% or more of the recovered solid carbon 1 were particles with a particle diameter of 14.8 μm or less.

[0073] Next, an example of producing solid carbon via methane will be described. Note that the methane used was produced by the methanation reaction shown in the above-mentioned reaction formula (7).

[0074] Solid carbon was produced from methane using an electric furnace 200, the schematic diagram of which is shown in Fig. 4, and a heating furnace 300, the schematic diagram of which is shown in Fig. 5. As shown in Fig. 4, the electric furnace 200 has a cylindrical furnace tube 20 arranged horizontally and a heater 29 for heating the furnace tube 20. As shown in Fig. 5, the heating furnace 300 has a furnace core tube 30 arranged vertically and a heater 39 for heating the furnace core tube 30, which is arranged along the furnace core tube 30.

[0075] (Production of solid carbon 3) First, as shown in Fig. 4, spherical iron balls 26, which were direct reduced iron obtained by reducing spherical iron ore pellets with a diameter of 10 mm, were placed in a dish-shaped container and charged as catalyst into the furnace of an electric furnace 200. 30 g (approximately 20 to 30 pieces) of iron balls 26 were charged into the furnace.

[0076] Then, methane (concentration 100%) was supplied as a raw material gas into the furnace through the gas inlet 22, which is one open end of the furnace tube 20, to produce solid carbon. The exhaust gas, containing unreacted methane and water vapor, was discharged from the other open end of the furnace tube to the outside of the system. Methane was supplied at a rate of 1.0 L / min (calculated at 0°C and 1 atmosphere).

[0077] The temperature of the methane (temperature inside the electric furnace 200) was controlled to 900°C by adjusting the output of the heater 29.

[0078] The methane supply was continued for 1 hour to precipitate solid carbon 3.

[0079] The solid carbon 3 was then recovered from the electric furnace 200 together with the iron balls 26, and sieved through a sieve with 125 μm openings to separate the solid carbon 3 from the iron balls 26, and the solid carbon 3 was recovered.

[0080] (Production of solid carbon 4) 500 g of spherical alumina balls 36 with a diameter of 6 mm were placed in a furnace core tube 30 (alumina tube, inner diameter 80 mm) of a heating furnace 300 shown in FIG. 5 to form a layer with a height of about 50 mm as a soaking zone.

[0081] Then, methane (concentration 100%) was supplied as a raw material gas into the furnace core tube 30 from the gas inlet 32 ​​at the bottom end of the furnace core tube 30. Methane was supplied at 1.0 L / min (value converted to 0°C and 1 atmosphere).

[0082] The temperature of the methane (temperature inside the furnace core tube 30) was controlled to 1400°C (±10°C) by adjusting the output of the heater 39.

[0083] The methane supply was continued for 1 hour to precipitate solid carbon 4.

[0084] The solid carbon 4 was then recovered from the furnace core tube 30 together with the alumina balls 36, and sieved through a sieve with 125 μm openings to separate the alumina balls 36 and the solid carbon 4, and the solid carbon 4 was recovered.

[0085] Table 1 shows the production conditions and states of Solid Carbons 1 to 4, the results of component analysis, and the microscopic states (TEM observation results) of Solid Carbons 1, 3, and 4. The values ​​of T.Fe, FeO, M.Fe, and C of Solid Carbons 1, 3, and 4 were determined in the same manner as for Solid Carbon 2.

[0086] 6, 7 and 8 show the TEM observation results (TEM images) of solid carbon 1, solid carbon 3 and solid carbon 4, respectively, in this order.

[0087] The solid carbon1,3 obtained by the reaction below 900°C was found to be fibrous in nature with an aspect ratio of 10 or more under TEM observation.

[0088] The solid carbon 4 obtained by the reaction at 1400°C was observed by TEM to be in the form of spherical particles, and the particle diameter measured in the TEM image was approximately 0.2 to 2.0 μm.

[0089] From the TEM observation results, it is believed that solid carbon 4 was precipitated at a high temperature (1400°C), which made it highly reactive, with the main reaction being the production of carbon in the gas phase, causing solid carbon 4 to precipitate in the form of spherical particles. In contrast, when solid carbon 1 and solid carbon 3 were precipitated at temperatures below 900°C, the reduction reaction of carbon monoxide (solid carbon 1) and the thermal decomposition reaction of methane (solid carbon 3) did not proceed easily, and reactions using iron as a catalyst occurred as the main reaction, causing solid carbon 1 and solid carbon 3 to precipitate in the form of fibers.

[0090] Although the TEM observation results of Solid Carbon 2 are not shown, as shown in Figure 3, Solid Carbon 2 was visually observed as an agglomerated powder, and its microstructure was fibrous, similar to Solid Carbons 1 and 3.

[0091] Coke was produced using the solid carbons 1 to 4 produced as described above. In this example, coke was produced by mixing the solid carbons 1 to 4 with coal.

[0092] Coal has the property of melting and solidifying during carbonization (caking property). Coal caking property is an essential property for producing coke. Caking property is determined by the properties (fluidity) of coal when it softens and melts. Therefore, when evaluating whether a certain brand of coal is suitable as a coke raw material, it is effective to use values ​​(measured or estimated values) related to the coal's softening and melting properties as an indicator.

[0093] In this test, Gieseler maximum fluidity (MF) (hereinafter referred to as MF value) was used as an index for evaluating caking or fluidity. MF value was determined according to the method specified in JIS M 8801. MF values ​​were compared using common logarithm (logMF).

[0094] Mixtures of coal A and solid carbon 1 (hereinafter, a mixture of coal and solid carbon such as coal A may be referred to as mixed coal) were evaluated as Production Examples 1 to 3. The blending ratio of coal A to solid carbon 1 (the amount of solid carbon added to the mixture (mass%)) is shown in Table 2. Table 2 also shows the logMF values ​​of the mixtures of Production Examples 1 to 3. Coal A was crushed to a sieve size of 0.425 mm or less (crushed into powdered coal) and then mixed with the solid carbon.

[0095] [Table 2]

[0096] In Production Examples 4 to 6, a blended coal of coal A and solid carbon 2 was evaluated. In Production Examples 7 to 9, a blended coal of coal A and solid carbon 3 was evaluated. In Production Examples 10 to 12, a blended coal of coal A and solid carbon 4 was evaluated. As with Production Examples 1 to 3, the blending ratios and logMF values ​​for each are shown in Table 2. Note that in Reference Production Example 1, only coal A was evaluated, and its logMF value is also shown in Table 2.

[0097] Although the logMF value is not particularly limited, if the logMF value is 1.6 or higher, no special coke production method is required, and coke can be produced without problems using a general coke production method (a method for carbonizing coal without mixing solid carbon). According to Table 2, within the range of this example, regardless of the type of solid carbon, when the amount of solid carbon added to the mixed coal is 5% by mass or less, the logMF value is 1.6 or higher, and the mixed coal can be evaluated as being suitable as a coke raw material. Furthermore, a logMF value of 2.0 or higher is even more preferable as a coke raw material.

[0098] In the case of mixed coals such as those in Production Examples 1 to 12, the logMF value of the mixed coal also depends on the type of coal mixed with the solid carbon. Therefore, the evaluation that a solid carbon addition amount of 5% or less is satisfactory based on these production examples is based on the assumption that the mixed coal will be mixed with Coal A.

[0099] Next, the mixed coal was carbonized to produce coke, and the crushing strength of the coke was evaluated. In addition, as a comparison with the mixed coal, coke was produced using only coal blend B and coal blend C, and the crushing strength of the coke was evaluated.

[0100] Coal Blend B and Coal Blend C were prepared by mixing multiple brands of coal to adjust the logMF value. The batch amounts for blending Coal Blend B and Coal Blend C were adjusted so that the total mass of each coal blend after mixing was 200 g.

[0101] Coal blend B has a weighted average Ro (average maximum vitrinite reflectance, JIS M 8816) of 1.0, weighted by the blending ratio of each brand, and a weighted average logMF value of 2.3, weighted by the blending ratio of each brand. Coal blend C has a weighted average Ro of 1.0, weighted by the blending ratio of each brand, and a weighted average logMF value of 2.7, weighted by the blending ratio of each brand.

[0102] The amount of solid carbon added to the mixed coal for evaluating crushing strength was 5% by mass or 10% by mass for each of solid carbons 1 to 4, based on the results of each of the above-mentioned production examples (Examples 1 to 8). Coal blend C was used for the mixed coal. Coal blend B was pulverized to a sieve opening of 3 mm or less (after being pulverized into pulverized coal) and then subjected to the test. Coal blend C was pulverized to a sieve opening of 3 mm or less (after being pulverized into pulverized coal) and then mixed with solid carbon. The carbon type and amount of solid carbon added for each mixed coal of Examples 1 to 8 are shown in Table 3.

[0103] [Table 3]

[0104] The carbonization of each of the mixed coals in Examples 1 to 8, and the coal blends B and C in Reference Examples 1 and 2 was carried out as follows.

[0105] The bulk density (dry mass basis) of each of the mixed coals in Examples 1 to 8, and the blended coals B and C in Reference Examples 1 and 2 was 830 kg / m 3 Then, with a 1 kg weight placed on the carbonization can, the mixture was carbonized in an electric furnace at an internal temperature of 1,050°C for 6 hours, and then removed from the electric furnace and cooled with nitrogen to obtain cokes of Examples 1 to 8 and Reference Examples 1 and 2.

[0106] Cylindrical samples with a diameter of 9.6 mm and a height of 10 mm were cut out from each of these carbonized cokes, and strength measurements (measurement of crushing strength) were performed using an autograph (Shimadzu Corporation, model: AGS-X). The displacement rate was 2 mm / min. The average value of the measurements for five cylindrical samples was taken as the crushing strength after calcination.

[0107] The crushing strength S (Pa) can be calculated using the following formula (10) based on the load P (N) at the time of breaking of the cylindrical sample, the height L (m) of the cylindrical sample, and the diameter D (m) of the cylindrical sample.

[0108] S = 2 × P / πLD (10)

[0109] The crushing strengths of the cokes of Examples 1 to 8 and Comparative Examples 1 and 2 obtained as described above are also shown in Table 3.

[0110] The results of the crushing strength of the cokes of Examples 1 to 8 show that the cokes of Examples 1 to 8 have crushing strengths comparable to those of the cokes of Reference Examples 1 and 2, which were produced using the same general coke production method (carbonization method) as the cokes produced from coal alone. The crushing strengths of the cokes of Examples 1 to 8 exceed 3 MPa, which is generally sufficient for use in a blast furnace. In other words, the cokes of Examples 1 to 8 have strengths sufficient to withstand use in a blast furnace.

[0111] As shown in Production Examples 1 to 12, a decrease in the logMF value was observed for the mixed coal. However, as described above, the cokes of Examples 1 to 8 have crushing strengths comparable to those of Reference Example 1 and Reference Example 1, which were produced from coal alone. Therefore, it is considered that the effect of solid carbon on crushing strength (especially the effect of reducing crushing strength) is small in cokes produced from mixed coal. This is presumably because the solid carbons 1 to 3 according to the present examples are fibrous carbon, and reinforcement (strength improvement effect) by these fibers was obtained.

[0112] As described above, the coke manufacturing method according to this embodiment makes it possible to provide coke containing solid carbon produced from a carbon-containing gas such as a blast furnace by-product gas, and having strength sufficient for use in a blast furnace. Furthermore, by producing solid carbon from a carbon-containing gas such as a blast furnace by-product gas, it is possible to provide a technology for manufacturing carbon materials with low carbon dioxide emissions. Furthermore, it is possible to reduce carbon dioxide emissions during coke manufacturing. Furthermore, by making it possible to produce coke with strength sufficient for use in a blast furnace using solid carbon produced from a carbon-containing gas such as a blast furnace by-product gas, it is possible to reduce carbon dioxide emissions in the steelmaking process.

[0113] In this way, a method for producing coke can be provided.

[0114] The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0115] The present invention can be applied to a method for producing coke. [Explanation of symbols]

[0116] 10: Furnace tube 100: Reactor 12: Alumina support 14: Alumina ball 15: Thermocouple 16: Ore 18: Gas inlet pipe 19: Heater 2: Solid carbon 20: Furnace cylinder 200: Electric furnace 22: Gas inlet 26: Iron ball 29: Heater 30: Furnace core tube 300:Heating furnace 32: Gas inlet 36: Alumina ball 39: Heater

Claims

1. a carbon production step of producing solid carbon from carbon monoxide or carbon dioxide; a coke production step of producing coke using coal and the solid carbon, When solid carbon is produced from carbon dioxide in the carbon production step, (1) performing a step of producing carbon monoxide from carbon dioxide and hydrogen by a reverse water gas shift reaction, and a step of producing the solid carbon from the produced carbon monoxide; or (2) A method for producing coke, comprising: a methane production step of reacting carbon dioxide with hydrogen to produce methane; and a methane decomposition step of thermally decomposing the methane produced in the methane production step to produce the solid carbon.

2. The method for producing coke according to claim 1 , wherein the carbon production step comprises reacting carbon monoxide with hydrogen to produce the solid carbon.

3. In the carbon production step, a methane production step in which carbon dioxide and hydrogen are reacted to produce methane; 2. The method for producing coke according to claim 1, further comprising a methane decomposition step of thermally decomposing the methane produced in the methane production step to produce the solid carbon.

4. The method for producing coke according to any one of claims 1 to 3, wherein the solid carbon has an iron content of 10 mass% or less.

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