Method for producing sintered ore

Abstract

Provided is a method for producing a sintered ore capable of preventing a reduction in yield when a carbon material having a low combustion initiation temperature is used. Provided is a method for producing a sintered ore, in which a raw material for sintering, which contains a carbon material as a solid fuel, is granulated to form a granulated raw material for sintering, and the granulated raw material for sintering is sintered to obtain a sintered ore, a carbon material in which at least two or more types of carbon materials are blended and the weighted average of the combustion initiation temperatures thereof is 550 DEG C or more is used for sintering. Preferably, a carbon material having a combustion initiation temperature of less than 550 DEG C is used as a part of the two or more types of carbon materials.

Description

Technical Field

[0001] The present invention relates to a method for producing sintered ore, comprising granulating a sintering raw material containing a carbon material as a solid fuel to prepare a sintering granulated raw material, and sintering the sintering granulated raw material to obtain a sintered ore. Background Art

[0002] In the manufacturing process of sintered ore, iron ore, flux, and carbon material as solid fuel are mixed and then sintered in a sintering machine using the combustion heat of the carbon material to produce sintered ore. Usually, coke powder is used as the carbon material, but in order to disperse the risk of price fluctuations of raw coal, failure of coke manufacturing equipment, etc., anthracite is sometimes used in addition to coke powder.

[0003] On the other hand, due to the increasing awareness of environmental protection in recent years, in addition to the idea of ​​risk diversification, the diversification of carbon materials has been carried out with the intention of reducing the burden on the environment. As an example, in Patent Document 1, a carbon material for the manufacture of sintered ore of sub-bituminous coal and lignite is proposed. The carbon material has the following properties: the reaction start temperature is below 550°C, the volatile component (VM) is above 1.0%, the atomic ratio of hydrogen and carbon (H / C) is above 0.040, and the pore volume with a pore size of 0.1 to 10 μm measured by mercury intrusion is 50 mm 3 In addition, Patent Document 2 proposes the use of a sintering raw material containing 10% by mass or more of a solid fuel having a combustion start temperature of less than 450° C. when using 30% or more of a high-crystallization-water iron ore containing 4.0% by mass or more of crystal water.

[0004] However, since the upper limit of the reaction start temperature is stipulated in the above, the deterioration of the yield in the sintered ore production process is not considered. In this regard, Patent Document 3 proposes the following method: in a double combustion sintering method in which a sintering charge layer is formed in two stages and each surface is ignited and sintered, coke and / or anthracite and a carbon material with a lower combustion start temperature than these are placed on the raw material on the lower stage side. In addition, Patent Document 4 proposes the following method: as agglomerating materials, a carbon material with a low combustion start temperature is added to powdered coke and / or anthracite in a range of 25 to 75% of the total carbon content, and at least one of a low combustion start temperature carbon material and a high combustion start temperature carbon material is added in the second half of the granulation process.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 4681688

[0008] Patent Document 2: Japanese Patent No. 4837799

[0009] Patent Document 3: Japanese Patent Application Publication No. 2020-186436

[0010] Patent Document 4: Japanese Patent Application Publication No. 2022-033594 Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, the method disclosed in Patent Document 3 is based on the premise of a two-stage ignition sintering method and cannot be applied to a general sintering method. In addition, in the method disclosed in Patent Document 4, since there are also types of carbon materials with low combustion starting temperatures, and their combustion starting temperatures vary, there is a risk of uniformly sorting them with carbon components.

[0013] The object of the present invention is to solve the above-mentioned problems and to provide a method for producing sintered ore, in which a sintering compound raw material containing carbon material as a solid fuel is granulated into a sintering granulated raw material, and the sintered granulated raw material is sintered to obtain sintered ore, thereby preventing the yield from being reduced when using carbon material with a low combustion start temperature.

[0014] Means for solving problems

[0015] The method for producing sintered ore of the present invention comprises granulating a sintering raw material containing a carbon material as a solid fuel to form a sintering granulated raw material, and sintering the sintering granulated raw material to obtain a sintered ore. In the manufacturing method, as the carbon material, a carbon material containing at least two or more carbon materials and having a weighted average combustion start temperature of 550°C or more is used for sintering.

[0016] In addition, in the method for producing a sintered ore of the present invention having the above-mentioned structure, the following is considered to be a more preferable solution.

[0017] (1) The mixed carbon material includes a carbon material having a combustion starting temperature lower than 550°C.

[0018] (2) The carbon material having a combustion starting temperature lower than 550° C. includes organic resources other than fossil fuels, or carbon material prepared using the organic resources as raw materials.

[0019] (3) The carbon material having a combustion starting temperature lower than 550° C. is coke made from biomass carbon, anthracite, waste plastic carbon, lignite and / or sub-bituminous coal.

[0020] (4) The entire amount of the blended carbon material is added before the granulation step.

[0021] Effects of the Invention

[0022] According to the method for producing sintered ore of the present invention, by using a carbon material prepared by mixing at least two or more carbon materials and having a weighted average combustion start temperature of 550° C. or higher as the carbon material for sintering, it is possible to suppress a reduction in yield when mixing with the carbon material in the sintered ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram showing one embodiment of a sintered ore production facility used in the sintered ore production method of the present invention.

[0024] Figure 2 This is a graph showing the relationship between the product yield and the weighted average of the combustion start temperature in Examples.

[0025] Figure 3 This is a graph comparing the product yields of the products added before and after carbon material granulation. DETAILED DESCRIPTION

[0026] The following is a detailed description of the embodiments of the present invention. It should be noted that the following embodiments are examples of devices and methods for concretizing the technical concept of the present invention, rather than limiting the structure to the following content. That is, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0027] <About the manufacturing equipment of sintered ore used in the manufacturing method of sintered ore of the present invention>

[0028] Figure 1 Schematic diagram showing one embodiment of a sintered ore manufacturing facility 1 used in the sintered ore manufacturing method of the present invention. The sintered ore manufacturing facility 1 includes a drum mixer 2 as a granulation device, a sintering machine 3, a crusher 4, a cooler 5, and a sieving device 6. A sintering raw material containing an iron-containing raw material, an auxiliary raw material, and a coagulating material such as a carbon material or coke powder is granulated in the drum mixer 2 by adding granulation water. The granulated raw material for sintering is transported to the sintering machine 3.

[0029] The sintering machine 3 is a belt sintering machine (Dwight Lloyd). The sintering machine 3 includes a sintering raw material supply device 11, a circular movable tray trolley 12, an ignition furnace 13 and a bellows 14. The granulated sintering raw material after granulation is loaded into the tray trolley 12 from the sintering raw material supply device 11 to form a loading layer of the sintering granulated raw material. In the ignition furnace 13, the condensed material contained in the surface layer of the loading layer is ignited, and the air in the loading layer is sucked downward through the bellows 14, thereby, the combustion melting belt in the loading layer moves downward of the loading layer. Through the movement of the combustion melting belt, the loading layer is sintered to become a sintered cake.

[0030] When the air in the loading layer is sucked downward by the wind box 14, gas fuel and / or oxygen-enriched air can be supplied from above the loading layer. The gas fuel is any combustible gas selected from blast furnace gas, coke oven gas, converter gas, city gas, natural gas, methane gas, ethane gas, propane gas and their mixed gases.

[0031] The sintered block is crushed by the crusher 4 and cooled by the cooler 5. The crushed sintered block is screened by the screening device 6 into sintered ore with a particle size of more than 5 mm and returned ore with a particle size of less than 5 mm. The returned ore is used again as a sintering raw material. In this way, sintered ore is produced.

[0032] <About the method for producing sintered ore of the present invention>

[0033] The method for producing sintered ore of the present invention is characterized in that at least two or more carbon materials are blended as a solid fuel and the weighted average of the combustion start temperatures thereof is 550° C. or higher. The carbon materials used in the method for producing sintered ore of the present invention are described below.

[0034] Among the various types of carbon materials used to reduce environmental load, carbon materials derived from biomass (hereinafter referred to as biochar) have attracted much attention. Since biochar absorbs carbon dioxide gas before the growth of the plant that is its raw material, from the perspective of carbon neutrality, when the fuel of the biochar is used, the amount of carbon dioxide gas released to the outside of the system can be counted as zero emission. Therefore, even in the iron ore sintering process that usually uses powdered coke, the use of biochar is considered. As a characteristic of biochar, its combustion start temperature is lower than that of coke (600-750°C), and is roughly below 550°C.

[0035] In the sintering process of the above-mentioned sintering machine 3, flux and carbon material are added to the iron ore and continuously loaded onto the sintering machine 3 to form a sintering bed consisting of a loading layer of sintering raw materials. After ignition at the upper end of the sintering bed, exhaust gas is sucked from the lower end so that the combustion of the carbon material is propagated from the upper end to the lower end of the sintering bed, and the heat is used to react and agglomerate the iron ore and flux. The exhaust gas from the lower layer is sucked by a blower, and the sucked exhaust gas passes through the pipeline and is discharged from the chimney through the dust collector, desulfurization and denitrification equipment.

[0036] As mentioned above, biochar is characterized by its low combustion start temperature. This is because biochar is porous compared to the powdered coke (fossil fuel source) generally used in the sintering process, and its surface area is very high, so a high combustion rate can be obtained even at low temperatures. Therefore, biochar shows a tendency to have a low combustion start temperature but a high subsequent combustion rate.

[0037] The combustion reaction of carbon materials is a gas-solid reaction. The carbon materials react with oxygen in the surrounding gas and burn. In gas-solid reactions under gas flow conditions such as sintering, there is an extremely thin layer of area called a gas film on the solid surface. The gas film is not affected by the turbulence on the outside and maintains a laminar flow. The combustion of carbon materials is achieved by oxygen diffusing from the outside of the gas film into the gas film and reaching the surface of the carbon materials for combustion. Among them, when the combustion rate of the carbon materials is very fast, even if the surrounding oxygen concentration is high, the surface oxygen consumption rate generated by the combustion of the carbon materials becomes larger than the oxygen supply rate generated by the diffusion of oxygen in the gas film, and the oxygen concentration in the gas film decreases. Therefore, the carbon materials are incompletely burned and the amount of carbon monoxide produced increases. Therefore, when the combustion rate is very fast, part of the combustion heat of the carbon materials is discharged to the outside of the system as carbon monoxide, so the reaction heat used for sintering is reduced, thereby reducing the yield. Here, by reducing the combustion rate of the carbon material used and making the combustion start temperature above 550°C, the diffusion rate in the gas boundary film under oxygen supply in the combustion reaction can be resolved, and part of the combustion heat can be suppressed from being discharged to the outside of the system as carbon monoxide.

[0038] The burning rate of carbon materials is believed to be affected by the decrease in the burning rate constant per unit area of ​​the carbon materials, the decrease in the surface area, etc. However, the burning rate constant is a value determined by the properties of the carbon materials and is difficult to control. There are methods to reduce the surface area, such as increasing the particle size of the carbon materials or coating the surface. However, the particle size needs to be increased to a size that is difficult to use with existing processes, and the coating of powders is technically difficult and it is difficult to control the target surface area.

[0039] In summary, it is realistic to mix a carbon material with a slow combustion rate when using a carbon material with a fast combustion rate to comprehensively control the combustion rate. Therefore, in the present invention, especially when using a carbon material with a combustion start temperature lower than 550°C other than fossil fuels such as biomass charcoal, a carbon material with a higher combustion start temperature is added to make the weighted average of the combustion start temperature of the carbon material after mixing above 550°C. In this way, while suppressing the reduction in the yield of sintered ore, the CO2 emission outside the system can be suppressed from the perspective of carbon neutrality.

[0040] In addition, as a preferred embodiment, it is preferred that the entire amount of the carbon material after at least two or more carbon materials are mixed is added before the granulation step. This can suppress the segregation of the mixed carbon materials, reduce the deviation of the combustion start temperature of the carbon materials mixed in the sintering granulation raw material, and as a result, suppress the deviation of the yield rate of the sintered ore.

[0041] It should be noted that as a carbon material with a combustion start temperature lower than 550°C, it is preferred to use organic resources other than fossil fuels, or carbon materials made from the above-mentioned organic resources as raw materials, more specifically, coke made from biomass charcoal, anthracite, waste plastic charcoal, lignite and / or sub-bituminous coal as raw materials.

[0042] [Example]

[0043] <Example 1>

[0044] A batch-type sintering test apparatus is used, and a material obtained by mixing at least two or more carbon materials with different combustion start temperatures is used, and sintering is performed under conditions that make the input heat uniform to produce sintered ore. As carbon materials, commonly used powdered coke, anthracite, other biomass charcoal with a combustion start temperature below 550°C, and lignite are used. Examples of using the above carbon materials alone are referred to as reference examples 1-4, examples of mixing at least two or more of the above carbon materials and having a weighted average of a combustion start temperature below 550°C are referred to as comparative examples 1-3, and examples of mixing at least two or more of the above carbon materials and having a weighted average of a combustion start temperature above 550°C are referred to as embodiments 1-6. At this time, the combination of raw materials other than the carbon materials is constant. In addition, the yield of the sintered ore made using the carbon materials of each example is calculated as the ratio of 5 mm or more when all the samples after sintering are dropped 4 times from a height of 2m. The results are shown in Table 1, and the relationship between the product yield and the weighted average of the combustion start temperature based on the results is shown in Table 1. Figure 2 .

[0045] Here, the combustion start temperature is calculated by the following method. Weigh 10 mg of the carbon material as the object, and heat it at 10°C / min while circulating air at 200 ml / min in an electric furnace with a differential thermal analysis function. When the combustion start temperature is reached, the carbon material starts to burn and generates heat rapidly. At this time, a relationship line between time and heat change is drawn with time as the horizontal axis and heat change in differential thermal analysis as the vertical axis. In differential thermal analysis, the intersection of the extension of the line of heat change before the rapid heat generation is detected and the extension of the line of heat change just after the rapid heat generation is detected is taken as the combustion start temperature.

[0046] [Table 1]

[0047]

[0048] From Table 1 and Figure 2 From the results, it can be seen that as the weighted average of the combustion start temperature after blending increases, the product yield increases. In addition, it can be seen that in Comparative Example 1-3, in which the weighted average of the combustion start temperature after blending is lower than 550°C, the product yield is a relatively low value. On the other hand, it can be seen that in Example 1-6, in which the weighted average of the combustion start temperature after blending at least two types of carbon materials is above 550°C, the product yield is higher than that of Comparative Example 1-3, and the increase in the product yield reaches saturation from around 550°C. Furthermore, in biomass charcoal and lignite having a combustion start temperature lower than 550°C, when used alone (Reference Example 1, Reference Example 2), the product yield is a relatively low value. However, by mixing them with other carbon materials and making the weighted average of the combustion start temperature above 550°C (Example 1-6), the product yield becomes higher. From the above, it can be seen that even a carbon material with a sintering start temperature lower than 550°C, which has a low product yield and cannot be used alone, can be used as a carbon material by combining it with other carbon materials so that the weighted average sintering start temperature is above 550°C.

[0049] <Example 2>

[0050] The carbon material prepared according to the conditions of Example 1 in Table 1 was added before the granulation process and in the second half of the granulation process. The deviation of the product yield was investigated multiple times. Figure 3 As shown. As a result, in the standard of adding carbon material before granulation, the product yield rate has a deviation of about 8%, and the average value is 87%. On the other hand, in the standard of adding carbon material halfway after granulation, there is a deviation of about 17%, and there are also standards exceeding 85%, but as an average, it is a value lower than the standard of adding carbon material before granulation. From the above, it can be seen that it is a preferred solution to add the entire amount of carbon material after mixing before the granulation process.

[0051] [Industrial Applicability]

[0052] According to the method for producing sintered ore of the present invention, by using a predetermined carbon material, it is possible to prevent a decrease in yield when using a carbon material having a low combustion start temperature, and the method is industrially useful.

[0053] Description of Reference Numerals

[0054] 1 Sintered ore manufacturing equipment

[0055] 2 drum mixer

[0056] 3Sintering machine

[0057] 4 Crusher

[0058] 5 Cooler

[0059] 6Screening device

[0060] 11Raw material supply device

[0061] 12-Pallet Trolley

[0062] 13 Ignition stove

[0063] 14 Bellows

Claims

1. A method for producing sintered ore, characterized in that: A sintering raw material containing a carbon material as a solid fuel is granulated to form a sintering granulated raw material, and the sintering granulated raw material is sintered to obtain a sintered ore. In the manufacturing method, as the carbon material, a carbon material that is mixed with at least two or more carbon materials and whose weighted average combustion start temperature is above 550°C is used for sintering.

2. The method for producing sintered ore according to claim 1, wherein: The blended carbon material contains a carbon material having a combustion starting temperature lower than 550°C.

3. The method for producing sintered ore according to claim 2, wherein: The carbon material having a combustion start temperature lower than 550° C. includes organic resources other than fossil fuels, or carbon materials produced using the organic resources as raw materials.

4. The method for producing sintered ore according to claim 3, wherein: The carbon material with a combustion starting temperature lower than 550° C. is coke made from biomass carbon, anthracite, waste plastic carbon, lignite and / or sub-bituminous coal.

5. The method for producing a sintered ore according to any one of claims 1 to 4, characterized in that: The entire amount of the blended carbon material is added before the granulation step.

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