Method for producing iron ore pellets

Abstract

Provided is a method for producing iron ore pellets, whereby high-strength iron ore pellets can be obtained and carbon neutralization is facilitated. A method for producing iron ore pellets according to the present invention is characterized by comprising: a mixing step for obtaining a mixture by mixing iron ore having a total Fe content of 63 mass% or less, solid carbon, a binder, and auxiliary starting materials; a granulation step in which the mixture is granulated to obtain green pellets; a calcining step for calcining the green pellets to obtain iron ore pellets by heating the green pellets from the outside by burning CH4 gas and heating the green pellets from the inside by burning the solid carbon; the solid carbon contains carbon generated from one or more substances selected from the group consisting of CO2 gas, CO gas, and CH4 gas.

Description

Technical Field

[0001] The present invention relates to a method for producing iron ore pellets. Background Art

[0002] Iron ore pellets refer to materials that are made by granulating iron ore powder into a material with properties (such as size, strength, reducibility, etc.) suitable for being put into a blast furnace or a solid reduction furnace. In general, iron ore pellets are manufactured by the following steps: a step of mixing iron ore powder, a binder, and any auxiliary raw materials to obtain a mixture; a step of granulating the mixture to obtain green pellets; and a calcining step of calcining the green pellets to obtain iron ore pellets. In this specification, the pellets that have just been granulated and before calcination are referred to as "green pellets". Here, as described in Non-Patent Document 1, it is known that a carbon material such as anthracite is added to the above mixture. In the calcining step, natural gas with CH4 gas as the main component is burned to heat the green pellets, and the heat generated by the combustion is conducted from the surface of the green pellets to the inside. Therefore, insufficient heating inside the pellets may lead to a decrease in strength. Therefore, in order to compensate for the heat inside the pellets, a carbon material such as anthracite is added to the green pellets, and the carbon material is burned in the calcining step, thereby also heating the green pellets from the inside.

[0003] Prior art literature

[0004] Patent Literature

[0005] Non-patent literature 1: Volodymyr Shatokha, “Iron Ores and Iron Oxide Materials”, IntechOpen, published on July 11, 2018, p41-59 Summary of the invention

[0006] In order to prevent the green pellets from being pulverized during the treatment before entering the calciner and the powder from being attached to the calciner, it is important to ensure the strength of the green pellets and the strength of the iron ore pellets, and continuous improvement is required.

[0007] In addition, due to the concept of reducing CO2 emissions in recent years, carbon-neutral steelmaking methods are highly anticipated. When manufacturing iron ore pellets, the combustion of CH4 gas and carbon materials in the calcination process is the main factor of CO2 emission. As a method for manufacturing iron ore pellets without CO2 emissions, a method of using non-calcined green pellets as iron ore pellets by using organic / inorganic binders has also been proposed. However, non-calcined green pellets have the following problems in terms of quality. If the organic binder is heated to a high temperature, carbonization or a gasification reaction with CO2 accompanied by carbonization (C+CO2→2CO) will occur, so it cannot exist as a binder. It can be imagined that it is difficult to show the binder properties when using organic binders at high temperatures. In addition, although silicates (sodium silicate, calcium silicate) can be cited as inorganic binders, silicate itself needs to be separated from pig iron or molten steel as slag in the ironmaking and steelmaking processes, and excess heat is required to melt the pig iron. In addition, there is also the issue of inorganic binders being discharged as slag, that is, excess materials. Furthermore, sodium in sodium silicate is solid at low temperatures, but it will gasify at temperatures below 1000°C, so it should be avoided that it will become a substance remaining in the blast furnace. Under the premise of manufacturing iron ore pellets through the calcination process, there has been no technology that aims at carbon neutrality.

[0008] Therefore, in view of the above problems, an object of the present invention is to provide a method for producing iron ore pellets that can obtain high-strength iron ore pellets and contribute to carbon neutralization.

[0009] In order to achieve this object, the present inventors have focused on improving the carbon material added to the green pellets. That is, as the carbon material added to the green pellets, it is conceived to use solid carbon containing carbon generated by one or more selected from CO2 gas, CO gas and CH4 gas. In this case, although CO2 is generated by the combustion of the carbon material, the above-mentioned greenhouse gas will be consumed as a raw material of the carbon material, thus contributing to carbon neutralization. In addition, according to the research of the present inventors, it was unexpectedly discovered that by using solid carbon (carbon material) containing carbon generated by one or more selected from CO2 gas, CO gas and CH4 gas, the strength of the iron ore pellets can also be improved.

[0010] The gist of the present invention completed based on the above findings is as follows.

[0011] [1] A method for producing iron ore pellets, characterized by comprising the following steps:

[0012] In a mixing step, iron ore having a total Fe content of 63% or less, solid carbon, a binder and auxiliary materials are mixed to obtain a mixture,

[0013] a granulation step of granulating the mixture to obtain green pellets;

[0014] The calcining step heats the green pellets from the outside by burning CH4 gas and heats the green pellets from the inside by burning the solid carbon, thereby calcining the green pellets to obtain iron ore pellets.

[0015] Furthermore, the solid carbon includes carbon generated from one or more selected from CO2 gas, CO gas and CH4 gas.

[0016] [2] The method for producing iron ore pellets according to [1], wherein the solid carbon includes carbon generated from one or both of CO2 gas and CO gas.

[0017] [3] The method for producing iron ore pellets according to [1], wherein the CH 4 gas used for generating the carbon includes CH 4 gas generated from one or both of CO 2 gas and CO gas.

[0018] [4] The method for producing iron ore pellets according to any one of [1] to [3], wherein the carbon includes carbon generated using iron as a catalyst.

[0019] [5] The method for producing iron ore pellets according to any one of [1] to [4], wherein the ratio of the carbon in the solid carbon is 10% by mass or more.

[0020] [6] The method for producing iron ore pellets according to any one of [1] to [5], wherein the CH4 gas used in the calcining step includes CH4 gas generated from one or both of CO2 gas and CO gas.

[0021] According to the method for producing iron ore pellets of the present invention, high-strength iron ore pellets can be obtained and carbon neutrality can be contributed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram showing a vertical reactor used in a carbon production test using CO gas as a raw material.

[0023] Figure 2 Photographs showing the appearance of (a) sintered ore and (b) solid carbon after the carbon generation test.

[0024] Figure 3 (a) and (b) are schematic diagrams showing an apparatus used in a carbon generation test using CH4 gas as a raw material.

[0025] Figure 4 (a) to (c) show the TEM observation results of the solid carbon obtained in each carbon generation test. DETAILED DESCRIPTION

[0026] Hereinafter, an embodiment of the method for producing iron ore pellets according to the present invention will be described. It should be noted that the embodiment described below is an example of specific embodiment of the present invention, and the configuration of the present invention is not limited to this specific example.

[0027] A method for manufacturing iron ore pellets according to one embodiment of the present invention is characterized in that it comprises the following steps: a mixing step of mixing iron ore, solid carbon (carbon material), a binder and auxiliary raw materials to obtain a mixture; a granulation step of granulating the mixture to obtain green pellets; a calcination step of burning CH4 gas to heat the green pellets from the outside and burning the solid carbon to heat the green pellets from the inside, thereby calcining the green pellets to obtain iron ore pellets; and the solid carbon contains carbon generated from one or more selected from CO2 gas, CO gas and CH4 gas.

[0028] The mixture for manufacturing iron ore pellets is composed of iron ore, solid carbon, binder and auxiliary materials. In this embodiment, the iron ore includes ore with a total Fe content (T.Fe) of 63% by mass or less. Iron ore with a T.Fe of 63% by mass or less is inexpensive and suitable for manufacturing.

[0029] In order to fully obtain the effect of improving the strength of the green pellets, the amount of solid carbon in the iron ore pellets is preferably 0.80% by mass or more relative to the amount of iron ore in the iron ore pellets. On the other hand, if the solid carbon is excessively contained, the heat is too much in the calcination process, resulting in melting of the iron ore pellets. Therefore, the amount of solid carbon in the iron ore pellets is preferably 2.00% by mass or less relative to the amount of iron ore in the iron ore pellets.

[0030] Solid carbon includes carbon generated from one or more selected from CO2 gas, CO gas and CH4 gas. That is, as the carbon material (solid carbon) added to the green pellets, carbon generated from one or more selected from CO2 gas, CO gas and CH4 is used. In this case, although CO2 is generated by the combustion of the carbon material, the above-mentioned greenhouse gas is consumed as a raw material of the carbon material, thereby contributing to carbon neutralization. In addition, by adding carbon generated from one or more selected from CO2 gas, CO gas and CH4 gas to the green pellets, the effect of improving the strength of the green pellets and iron ore pellets can be obtained.

[0031] The proportion of the above carbon in the solid carbon added to the green pellets is preferably 10% by mass or more, more preferably 50% by mass or more, and most preferably 100% by mass. The greater the amount of the above carbon, the higher the effect of high strength and the greater the contribution to carbon neutralization. In addition, when the proportion of the above carbon in the solid carbon added to the green pellets is less than 100% by mass, the remainder of the solid carbon may be, for example, anthracite.

[0032] The solid carbon preferably includes carbon generated from one or both of CO2 gas and CO gas. In addition, when the solid carbon includes carbon generated from CH4 gas, the CH4 gas used in the generation of the carbon preferably includes CH4 gas generated from one or both of CO2 gas and CO gas. The reaction for generating solid carbon from CO2 gas, CO gas or CH4 gas is not particularly limited, but the following reactions can be mentioned.

[0033] [Reaction of generating solid carbon from CO gas]

[0034] Solid carbon can be generated from CO gas by the Bourdeau reaction shown in reaction formula (1). The Bourdeau reaction can generate solid carbon from CO gas at about 700° C. or less.

[0035] 2CO=C+CO2···(1)

[0036] Solid carbon can be generated from CO gas by the reverse water-gas reaction shown in reaction formula (2). The reverse water-gas reaction can generate solid carbon from CO gas at a temperature below about 650°C.

[0037] CO+H2=C+H2O···(2)

[0038] It is also possible to generate CH4 gas from CO gas by a methanation reaction as shown in reaction formula (3), and to generate solid carbon from CH4 gas by a thermal decomposition reaction as shown in reaction formula (4). The methanation reaction can generate CH4 gas from CO gas at a temperature below about 650°C, and the thermal decomposition reaction can generate solid carbon from CH4 gas in the air at a temperature above about 500°C.

[0039] CO+3H2=CH4+H2O···(3)

[0040] CH4=C+2H2···(4)

[0041] Solid carbon can be generated from CO gas by the decomposition reaction shown in reaction formula (5). The decomposition reaction can generate solid carbon from CO gas under low oxygen partial pressure.

[0042] 2CO=2C+O2···(5)

[0043] [Reaction of generating solid carbon from CO2 gas]

[0044] Solid carbon can be generated from CO2 gas by the reverse water-gas reaction shown in reaction formula (6). The reverse water-gas reaction can generate solid carbon from CO2 gas at a temperature below about 650°C.

[0045] CO2+2H2=C+2H2O···(6)

[0046] CO2 gas can be converted into CO gas by the reverse water-gas shift reaction shown in reaction formula (7), and solid carbon can be converted into CO gas by the reverse water-gas shift reaction shown in reaction formula (2). The reverse water-gas shift reaction can convert CO2 gas into CO gas at a temperature above about 850°C.

[0047] CO2+H2=CO+H2O···(7)

[0048] CO+H2=C+H2O···(2)

[0049] It is also possible to generate CH4 gas from CO2 gas by the methanation reaction shown in reaction formula (8), and to generate solid carbon from CH4 gas by the thermal decomposition reaction shown in reaction formula (4). The methanation reaction can generate CH4 gas from CO2 gas at a temperature below about 600°C.

[0050] CO2+4H2=CH4+2H2O···(8)

[0051] CH4=C+2H2···(4)

[0052] Solid carbon can be generated from CO2 gas by the decomposition reaction shown in reaction formula (9). The decomposition reaction can generate solid carbon from CO2 gas under low oxygen partial pressure.

[0053] CO2=C+O2···(9)

[0054] [Reaction of generating solid carbon from CH4 gas]

[0055] Solid carbon can be generated from CH4 gas through the thermal decomposition reaction shown in reaction formula (4).

[0056] CH4=C+2H2···(4)

[0057] The gas used in the carbon generation reaction may be any single gas of CO2 gas, CO gas or CH4 gas, or a gas obtained by mixing two or more of the above three gases, or a gas mixture of one or more of the above three gases and H2 gas or N2 gas, etc. For example, a gas mixture of 31% CO, 19% H2 and 50% N2 by volume may be used.

[0058] In addition, as the solid carbon added to the green pellets, any one of carbon generated from CO 2 gas, carbon generated from CO gas, and carbon generated from CH 4 gas may be used alone, or two or more thereof may be mixed and used.

[0059] Solid carbon is preferably carbon generated using iron as a catalyst. It is known that iron can be used as a catalyst in the Boudouard reaction shown in reaction formula (1) and the thermal decomposition reaction of CH4 shown in reaction formula (4). In addition, it is known that iron oxide can be used as a catalyst in the reverse water-gas shift reaction shown in reaction formula (7). Therefore, when generating solid carbon, sintered ore or direct reduced iron can be charged into the furnace and the iron and iron oxide contained in the sintered ore or direct reduced iron can be used as catalysts. In addition, in the high-temperature reaction such as the thermal decomposition reaction of CH4 shown in reaction formula (4), alumina can also be charged into the furnace in order to maintain the temperature in the furnace.

[0060] The solid carbon is preferably in a fibrous form, and the aspect ratio (length / diameter) is preferably greater than 10. When the solid carbon is a carbon fiber, the strength of the iron ore pellet can be appropriately obtained. In addition, the solid carbon can also be in a spherical form. When the solid carbon is spherical, the binder effect of the microparticles can be obtained, and the strength of the iron ore pellet can be appropriately obtained. In addition, when the solid carbon is spherical, its cumulative particle size D90 is preferably about 10 to 50 μm. In the solid carbon (carbon material) generated from one or more selected from CO2 gas, CO gas and CH4 gas, the carbon content is preferably 50 mass% or more, and the remainder may contain Fe, FeO, etc.

[0061] As the iron ore pellets, bentonite is preferred, but any known or arbitrary binder such as an organic or inorganic binder that can achieve the same effect may be used. In order to fully achieve this effect, the binder is preferably contained in an amount of 0.1% by mass or more relative to the amount of iron ore in the iron ore pellets. On the other hand, if the binder is contained in excess, in addition to the increase in manufacturing cost, the effect decreases as the content increases. Therefore, the binder is preferably contained in an amount of 4.0% by mass or less relative to the amount of iron ore in the iron ore pellets.

[0062] Iron ore pellets may be mixed with quicklime, limestone (CaCO3), dolomite (CaMg(CO3)2), etc. as auxiliary raw materials. The auxiliary raw materials are used to adjust the basicity of the iron ore pellets. The basicity of the iron ore pellets is calculated based on the weight ratio of CaO / SiO2 contained in the iron ore pellets. The basicity of the iron ore pellets is preferably 0.01 to 1.5.

[0063] Iron ore pellets are produced by general crushing, mixing, granulation, and calcination steps. The crushing step can use a general crusher such as a ball mill. The mixing step can use a general concrete mixer, a high-speed stirring mixer, etc. The granulation step can use a general granulator, a drum mixer, etc.

[0064] The Blaine index of the pulverized iron ore is preferably 2000 to 4000 cm 2The Blaine index is a value measured using a Blaine air permeation device specified in JIS R 5201: 2015, and indicates the specific surface area of ​​the powder. In the pelletizing process, the Blaine index is used as a management index for ore particle size, and a higher value means finer powder.

[0065] The green pellets obtained by granulation preferably have a particle size of about 9.5 to 12 mm. When the particle size of the green pellets is less than 9.5 mm, the air permeability when filled into a blast furnace as calcined pellets deteriorates. When the particle size of the green pellets exceeds 12 mm, the reducibility is reduced.

[0066] The calcination process can use a general rotary kiln, electric furnace, etc. In the calcination process, CH4 gas is burned to heat the green pellets from the outside, and solid carbon is burned to heat the green pellets from the inside. The calcination conditions are preferably a furnace temperature of 1200 to 1350°C, and the holding time at the furnace temperature is 5 to 30 minutes.

[0067] From the viewpoint of carbon neutralization, the CH4 gas used in the calcination step preferably contains CH4 gas generated from one or both of CO2 gas and CO gas. The method for generating CH4 gas is not particularly limited, and for example, the CH4 gas can be generated by the methanogenic reaction shown in reaction formulas (3) and (8).

[0068] CO2+4H2=CH4+2H2O···(8)

[0069] CO+3H2=CH4+H2O···(3)

[0070] Example

[0071] As raw materials for iron ore pellets, iron ore, a binder, and auxiliary materials were prepared. The composition of the iron ore used is shown in Table 1. The iron ore was dried at 105°C for 24 hours and then pulverized to obtain a pellet with a Blaine index of 2560 cm 2 / g, and iron ore powder with a volume average diameter of 95 μm. Bentonite was prepared as a binder and limestone as a secondary raw material.

[0072] Table 1 (mass %)

[0073] T.Fe <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO LOI 61.50 3.70 2.30 0.07 0.09 5.4

[0074] Next, an experiment was conducted to generate solid carbon from CO gas or CH4 gas. The details are as follows. In addition, anthracite was prepared as solid carbon that was not generated from any of CO gas, CO2 gas, and CH4 gas. As anthracite, granular anthracite with a particle size of 1 mm or less and a C content of 85% by mass was prepared.

[0075] [Carbon generation test from CO gas]

[0076] Figure 1 The vertical reactor is used to generate carbon from CO gas. A schematic diagram of the vertical reactor. Alumina support 12, alumina balls 14, and sintered ore 16 are placed in order in a furnace core tube 10 with an inner diameter of φ80 mm. A gas of 31% CO, 19% H2, and 50% N2 (hereinafter referred to as a CO gas mixture) is passed through a gas inlet pipe 18 at 550°C or 800°C (heated by a heater 20 and measured by a thermocouple 22) for 3 hours and a gas flow rate of 17 L / min to generate solid carbon. The iron component contained in the sintered ore is used as a catalyst for carbon generation.

[0077] The reduced sample was sieved with a 0.125 mm sieve to separate the sintered ore and solid carbon. 1.5 wt% of the reduced sample was solid carbon. The photographs of (a) sintered ore and (b) solid carbon after the carbon generation test with a CO gas mixture at 800°C are shown in Figure 2 The solid carbon is a fine powder. When the cumulative particle size is measured, D10: 2.1 μm, D50: 6.61 μm, and D90: 14.8 μm. That is, more than 90% of the cumulative number of powders have a particle size of 14.8 μm or less. Table 2 shows the component analysis results of the solid carbon.

[0078] Table 2 (mass %)

[0079] T.Fe M.Fe FeO C 13.6 7.8 7.2 72.0

[0080] [Carbon generation test from CH4 gas]

[0081] use Figure 3 The devices shown in (a) and (b) generate carbon from CH4 gas. Figure 3 (a) In the electric furnace 30 shown, 30 g (about 20 to 30 pellets) of direct reduced iron (DRI) 32 obtained by reducing φ10 mm iron ore pellets is charged as a catalyst, and 100% CH4 gas is introduced from the gas inlet 34 at 900°C for 1 hour at a gas flow rate of 1.0 L / min to generate solid carbon. Figure 3 (b) A furnace core tube (alumina tube) 36 of φ80 mm was filled with 500 g of φ6 mm alumina balls 38 to form a soaking zone of about 50 mm in height, and 100% CH4 gas was introduced from a gas inlet 40 at a gas temperature of 1400 (±10)° C. (heated by a heater 42) for 1 h and a gas flow rate of 1.0 L / min to generate solid carbon. The reduced samples obtained in each test were sieved with a 0.125 mm mesh to separate DRI or alumina balls and solid carbon.

[0082] The morphology and carbon content of the solid carbon and anthracite generated under each condition are shown in Table 3. The TEM observation results of (a) solid carbon generated from a CO gas mixture at 550°C, (b) solid carbon generated from a CH4 gas at 900°C, and (c) solid carbon generated from a CH4 gas at 1400°C are shown in Table 3. Figure 4 The solid carbon obtained in the reaction below 900°C is fibrous, with an aspect ratio of 10 or more. The solid carbon obtained in the reaction at 1400°C is spherical, with a particle size of about 0.2 to 2.0 μm. This is believed to be because at 1400°C, the high reactivity causes the formation of carbon in the gas phase as the main reaction, while at 900°C or below, the thermal decomposition reaction of CH4 gas is difficult to proceed, and the formation reaction using iron as a catalyst occurs as the main reaction.

[0083] Table 3

[0084]

[0085] Prepare 1000g of iron ore powder, add various solid carbons in the amounts shown in Table 4 relative to the amount of iron ore, and add 1% by mass of bentonite relative to the amount of iron ore. Furthermore, add limestone to the iron ore powder in an amount set so that the basicity of the iron ore pellets is 0.1, and mix at 20rpm for 3 minutes using a concrete mixer. It should be noted that the amount of solid carbon in No. 2 to 7 is set in a manner that the same amount of carbon as the anthracite of No. 1 is contained. The ratio of the carbon contained in the anthracite to be replaced by the carbon contained in the solid carbons 1 to 4 is shown in the "Carbon Replacement Rate" of Table 4. Next, add the mixed raw materials to a 1.2m granulator, and granulate while adding water. Take pellet particles with a particle size of 9.5 to 12mm, and further roll the granulator for 10 minutes to obtain raw pellets.

[0086] Table 4

[0087]

[0088] [Determination of drop strength of green pellets]

[0089] In each of the invention examples and comparative examples, the drop strength of 10 green pellets was measured in a manner simulating transportation and charging in actual operation. The operation of dropping the green pellets from a height of 50 cm was repeated until cracking or destruction of the green pellets was confirmed. The number of times before the end (i.e., the number of times cracking or destruction was confirmed) was taken as the drop strength, and the average drop strength of 10 pellets is shown in Table 3.

[0090] The green pellets not used in the above test were placed in an electric furnace for calcination. The temperature was raised at 10°C / min in an atmospheric atmosphere, maintained at 1300°C for 10 minutes, and then cooled at 10°C / min. After cooling, the sample was taken out to obtain iron ore pellets. It should be noted that in the actual calcination process, the green pellets are heated by burning natural gas with CH4 gas as the main component, but in this test, an electric furnace was used to simulate the heating.

[0091] [Determination of crushing strength of iron ore pellets]

[0092] In each of the invention examples and comparative examples, the crushing strength (kgf) of 10 iron ore pellets was measured using an Autograph. The displacement speed was set to 2 mm / min, and the average value of the 10 pellets is shown in Table 3.

[0093] As can be seen from Table 4, the inventive examples are superior to the comparative examples in terms of the drop strength of the green pellets and the crushing strength of the iron ore pellets. In addition to the above, by replacing the solid carbon from the conventional anthracite with carbon generated from one or more selected from CO2 gas, CO gas and CH4 gas, it can help reduce CO2 emissions, and the effect of the present invention is obvious. It is further shown that by making the replacement rate of solid carbon 100% by mass and using CH4 gas generated from one or both of CO2 gas and CO gas in the carbon generation and calcination process, carbon neutralization can be achieved in the manufacture of iron ore pellets.

[0094] Industrial Applicability

[0095] According to the present invention, it is possible to provide a method for producing iron ore pellets that can obtain high-strength iron ore pellets and contribute to carbon neutralization.

[0096] Explanation of symbols

[0097] 10 furnace core tube

[0098] 12 Alumina support table

[0099] 14 Alumina Ball

[0100] 16 Sintered Ore

[0101] 18 Gas inlet pipe

[0102] 20 Heater

[0103] 22 Thermocouple

[0104] 30 Electric furnace

[0105] 32 DRI obtained by reducing iron ore pellets

[0106] 34 Gas inlet

[0107] 36 Furnace core tube

[0108] 38 Alumina Ball

[0109] 40 Gas inlet

[0110] 42 Heater

Claims

1. A method for producing iron ore pellets, characterized in that: It has the following processes: In a mixing step, iron ore having a total Fe content of 63% or less, solid carbon, a binder and auxiliary materials are mixed to obtain a mixture, a granulation step of granulating the mixture to obtain green pellets, and A calcining step of heating the green pellets from the outside by burning CH4 gas and heating the green pellets from the inside by burning the solid carbon, thereby calcining the green pellets to obtain iron ore pellets; Furthermore, the solid carbon includes carbon generated from one or more selected from CO2 gas, CO gas and CH4 gas.

2. The method for producing iron ore pellets according to claim 1, wherein: The solid carbon includes carbon generated from one or both of CO 2 gas and CO gas.

3. The method for producing iron ore pellets according to claim 1, wherein: The CH 4 gas used in the generation of the carbon includes CH 4 gas generated from one or both of CO 2 gas and CO gas.

4. The method for producing iron ore pellets according to any one of claims 1 to 3, wherein: The carbon includes carbon produced using iron as a catalyst.

5. The method for producing iron ore pellets according to any one of claims 1 to 4, wherein: The ratio of the carbon in the solid carbon is 10% by mass or more.

6. The method for producing iron ore pellets according to any one of claims 1 to 5, wherein: The CH 4 gas used in the calcining step includes CH 4 gas generated from one or both of CO 2 gas and CO gas.

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