Carbon material used in sintered ore production

Abstract

Provided is a carbon material which is used in the production of sintered ore, and which is capable of preventing failures in an exhaust system caused by exhaust treatment, such as the generation of tar in piping and the generation of white smoke in an electric dust collector. A carbon material, which is a solid fuel for producing sintered ore, has an electrical conductivity of 1.0 * 10 <-9 > S / m or more and a volatile component (VM) of 15% or less. Furthermore, if the carbon material includes a plurality of carbon materials, the carbon material having a conductivity of 1.0 * 10-9 S / m or more at 80-200 DEG C among 80% or more of the plurality of carbon materials is included, and the weighted average of the volatile component (VM) is 15% or less.

Description

Technical Field

[0001] The present invention relates to a carbon material as a solid fuel used in the production of sintered ore. Background Art

[0002] In the manufacturing process of sintered ore, a mixture of iron ore, flux, and carbon material as solid fuel is sintered in a sintering machine using the combustion heat of the carbon material to produce sintered ore. Generally, coke powder is used as the carbon material, but in order to disperse the risk of price fluctuations of raw carbon and failure of coke manufacturing equipment, anthracite and the like are 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 is developing for the purpose of reducing the burden on the environment. As an example, in Patent Document 1, it is proposed that subbituminous coal and lignite are used as carbon materials for sintered ore production. The carbon material has a reaction start temperature of less than 550°C, a volatile component (VM) of more than 1.0%, a hydrogen to carbon atomic ratio (H / C) of more than 0.040, and a pore volume of 50 mm with a pore size of 0.1 to 10 μm measured by mercury intrusion. 3 In addition, Patent Document 2 proposes using a sintering raw material containing 10 mass % or more of a solid fuel having a combustion start temperature of less than 450° C. when using 30 mass % or more of high-crystallization water iron ore containing 4.0 mass % or more of crystal water.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4681688

[0007] Patent Document 2: Japanese Patent No. 4837799 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, the use of the carbon material described in Patent Document 1 and the use of the solid fuel described in Patent Document 2 focus on the productivity of sintered ore and NOx, and do not consider the impact on exhaust gas treatment. Therefore, in the use of the carbon material described in Patent Document 1 and the use of the solid fuel described in Patent Document 2, it is impossible to prevent the failure of the exhaust system caused by exhaust gas treatment, such as the generation of tar in the piping and the generation of white smoke in the electric dust collector.

[0010] The object of the present invention is to solve the above-mentioned problems and to provide a carbon material which, by using the carbon material in the manufacture of sintered ore, can prevent malfunctions in the exhaust system caused by exhaust gas treatment, such as the generation of tar in the piping and the generation of white smoke in the electric precipitator.

[0011] Means for solving problems

[0012] The carbon material used in sintered ore production is a carbon material as a solid fuel for sintered ore production according to the present invention, characterized in that the electrical conductivity is 1.0×10 -9 S / m or more, and the volatile matter (VM) is 15% or less.

[0013] It should be noted that, in the carbon material used for the production of sintered ore according to the present invention having the above-mentioned structure, the following means are considered to be more preferable solving means:

[0014] (1) When the carbon material comprises a plurality of carbon materials, the electrical conductivity of the plurality of carbon materials comprising 80% or more is 1.0×10 -9 A carbon material having a S / m or higher and a weighted average volatile matter (VM) of 15% or less;

[0015] (2) The carbon material includes a carbon material having a combustion starting temperature of 550° C. or less;

[0016] (3) The carbon material having a combustion start temperature of 550° C. or less is coke made from biomass carbon, anthracite, waste plastic carbon, lignite and / or sub-bituminous coal.

[0017] Effects of the Invention

[0018] According to the carbon material used in the manufacture of sintered ore of the present invention, by using the carbon material within the scope of the present limited conditions, the thermal decomposition products generated during combustion and the substances generated by the subsequent gas phase reaction can be prevented from adhering to the pipes and equipment in the exhaust system and causing failures. In addition, the dust collection efficiency can be prevented from being reduced and the generation of white smoke when the dust in the exhaust gas generated when the carbon material is used is collected by an electric dust collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [ Figure 1 ] is a schematic diagram showing an example of a manufacturing facility for sintered ore using the carbon material involved in the present embodiment. DETAILED DESCRIPTION

[0020] The following is a detailed description of the embodiments of the present invention. It should be noted that the following embodiments illustrate devices and methods for implementing the technical concept of the present invention, and their configuration is not limited 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.

[0021] <About a manufacturing facility for sintered ore using the carbon material for sintered ore manufacturing according to the present invention>

[0022] Figure 1 1 is a schematic diagram showing an example of a manufacturing facility 1 for sintered ore using a carbon material according to the present embodiment. The manufacturing facility 1 for sintered ore includes a drum mixer 2 as a granulating device, a sintering machine 3, a crusher 4, a cooler 5, and a screening device 6. Granulation water is added to the sintered raw material including an iron-containing raw material, an auxiliary raw material, a carbon material, and a coking material such as coke powder, and the granulation is performed by the drum mixer 2. The granulated sintered raw material is transported to the sintering machine 3.

[0023] The sintering machine 3 is, for example, a Dwight-Lloyd type sintering machine. The sintering machine 3 includes a sintering raw material supply device 11, a circular movable sintering trolley 12, an ignition furnace 13, and a wind box 14. The granulated sintering raw material is loaded into the sintering trolley 12 from the sintering raw material supply device 11 to form a loading layer of the sintering raw material. The condensed material contained in the surface layer of the loading layer is ignited by the ignition furnace 13, and the air in the loading layer is sucked downward by the wind box 14, so that the combustion melting zone in the loading layer moves downward of the loading layer. By the movement of the combustion melting zone, the loading layer is sintered to become a sintered cake.

[0024] When the air in the charging layer is sucked downward by the wind box 14, gas fuel and / or oxygen-enriched air may be supplied from above the charging layer. The gas fuel is any combustible gas selected from blast furnace gas, coke oven gas, converter gas, town gas, natural gas, methane gas, ethane gas, propane gas and their mixed gases.

[0025] The sintered cake is crushed by a crusher 4 and cooled by a cooler 5. The crushed sintered cake is sieved by a screening device 6 into sintered ore with a particle size of 5 mm or more and return ore with a particle size of less than 5 mm. The return ore is used again as a sintering raw material. Sintered ore is produced in this way.

[0026] <About the Carbon Material Used in the Production of Sintered Ore According to the Present Invention>

[0027] In terms of the diversification of carbon materials used to reduce environmental load, carbon materials from biomass (hereinafter referred to as biomass carbon) have attracted attention. Since biomass carbon absorbs carbon dioxide during the growth of plants as its raw material, from the perspective of carbon neutrality, the fuel using this biomass carbon can be regarded as a substance with zero carbon dioxide emissions to the outside of the system. Therefore, the use of biomass carbon has also been studied in the iron ore sintering process that usually uses coke powder. As a characteristic of biomass carbon, its combustion start temperature is lower than that of coke (600-800°C), which is about 550°C or less. In addition, it is known that the thermal decomposition reaction of biomass is greatly affected by the plant as the raw material. Even if it is all attributed to biomass carbon that has been subjected to heat treatment, its properties are very different and cannot be classified only by the combustion start temperature.

[0028] In the sintering process in the above-mentioned sintering machine 3, flux and carbon material are added to iron ore and continuously loaded onto the sintering machine 3 to form a sintering bed containing a loading layer of sintering raw materials. After the sintering bed is ignited at the upper end, exhaust gas is sucked from the lower end, so that the combustion of the carbon material propagates from the upper end of the bed to the lower end, and the heat is used to react and agglomerate the iron ore and the flux. The exhaust gas is sucked from the lower layer using a blower, and the sucked exhaust gas passes through the pipe, the dust collector, and the desulfurization and denitrification equipment and is discharged from the chimney.

[0029] When heating biomass, hydrocarbons with benzene rings above naphthalene are called tar, and the amount of tar produced by biomass is very large. The large amount of tar produced adheres to the pipes, filters for dust removal, impellers of blowers, etc., and sometimes becomes the cause of failure. Therefore, the selection of biomass carbon requires that the tar component produced, that is, the volatile component (VM) produced by thermal decomposition, be suppressed to a low level. It should be noted that VM is measured according to JIS M8812.

[0030] In addition, the dust in the exhaust gas contains a large amount of used carbon materials, which are recovered in the electric dust collector. When using an electric dust collector to capture low-conductivity dust, the surface of the dust collecting electrode is covered with low-conductivity dust, and it becomes difficult to remove it by hammering, etc. In addition, sparks caused by insulation breakdown are generated in the coated dust layer, inducing white smoke failures in the electric dust collector, etc. Therefore, it is necessary to add a certain conductivity or more to the biomass carbon used as a condition. It should be noted that the conductivity uses the inverse of the resistivity measured in accordance with JIS B9915.

[0031] Based on the above premise, in order to suppress the generation of tar during the production of sintered ore and to suppress the white smoke failure of the electric dust collector caused by the exhaust gas generated during the production of sintered ore, the electrical conductivity at 80°C to 200°C is set to 1.0×10 -9 S / m or more, and the volatile matter (VM) is 15% or less.

[0032] In the carbon material used in the production of sintered ore of the present invention, as a specific method for adjusting the conductivity and volatile components, it is possible to consider a method of selecting a carbon material that satisfies the aforementioned volatile components (VM) and conductivity, or a method of reducing the volatile components (VM) by dry distillation treatment, etc. In addition, when using multiple carbon materials, it is possible to cite a method of adjusting the blending in a manner that includes a carbon material whose weighted average of volatile components (VM) of more than 80% satisfies the aforementioned conditions and whose conductivity satisfies the aforementioned conditions, etc. The following further describes the method for measuring the conductivity and volatile components in the present invention in detail.

[0033] (About the measurement method of electrical conductivity)

[0034] The electrical conductivity was measured using the resistivity determined by the parallel plate electrode method (JIS B9915). The electrical conductivity was determined by calculating the reciprocal of the resistivity determined by the parallel plate electrode method (JIS B9915).

[0035] (About the measurement method of volatile matter (VM))

[0036] The volatile content (VM) was measured in accordance with JIS M8812. Specifically, a sample was placed in a crucible with a lid, set to avoid contact with air, and heated at 900°C for 7 minutes. The mass fraction (%) of the heat loss relative to the sample was calculated, and the water content determined at the same time was subtracted from the mass loss to obtain the volatile content (VM).

[0037] Example

[0038] Batch sintering tests were conducted using several carbon materials. The properties of the used carbon materials are shown in Table 1. The volatile matter (VM) was measured according to JIS M8812, and the electrical conductivity was the reciprocal of the resistance value measured according to JIS B9915.

[0039] [Table 1]

[0040] Carbon material types Volatile components (VM) Conductivity Coke powder 0.7％ <![CDATA[7.8×10 -4 S / m <!-- 3 -->]]> Anthracite A 14.7％ <![CDATA[2.3×10 -9 S / m]]> Anthracite B 15.6％ <![CDATA[8.9×10 -10 S / m]]> Anthracite C 9.0％ <![CDATA[1.4×10 -5 S / m]]> Anthracite D 9.5％ <![CDATA[2.5×10 -11 S / m]]> Biomass 77.1％ <![CDATA[3.4×10 -7 S / m]]>

[0041] Two batch sintering tests were conducted to evaluate the single carbon and multiple carbons of the carbon materials listed in Table 1. In the first one, a maximum of 100 continuous tests were conducted to investigate the number of times the current value of the blower with a rated current (commonly used) of 60A exceeded the upper limit of 75A. In the second one, the exhaust gas of the batch sintering test was treated using a small dust collector adjusted to the electric field strength of 3.4kV / cm of a normal actual machine to determine whether the attached dust could be removed by hammering. Table 2 shows the carbon material blending ratio as test conditions, the weighted average value of VM, and the results of the two evaluation methods. It should be noted that the same raw materials were used for the ore raw materials to be sintered.

[0042] [Table 2]

[0043]

[0044] Table 2 shows coke powder commonly used in sintering as a reference example. In the case of VM0.7%, even after 100 tests, the upper limit current was not exceeded, and the dust removal by hammering was possible. In Examples 1 and 2, and Comparative Examples 1 and 2, the classification is the same as anthracite. However, in the case of anthracite A with VM14.7% in Example 1, 100 tests were possible, but in the case of anthracite B with VM15.6% in Comparative Example 1, the upper limit current was exceeded in 33 tests, and it was difficult to remove the dust by hammering. Compared with Example 1, Example 2 has less VM and a high level of conductivity, and it can also be tested 100 times, and the dust can be removed by hammering. On the other hand, compared with Example 2, there is no big change in VM in Comparative Example 2, but there is a big difference in conductivity. Although 100 tests can be carried out, it is difficult to remove the dust by hammering. In addition, in Comparative Example 3 using only biomass with VM77.0%, although it became unusable after 17 times, it was possible to remove the dust by hammering. In Example 3 and Comparative Example 4, coke powder and anthracite B were mixed. The anthracite B could not be burned 100 times alone and it was difficult to remove the dust by hammering. In Example 3, where the coke powder was 80% and the weighted average of VM was 3.7%, 100 tests were possible and the dust could be removed by hammering. On the other hand, in Comparative Example 4, where the coke powder was 70% and the weighted average of VM was 5.2%, although the number of tests reached 100 times, it was difficult to remove the dust by hammering. In Example 5 and Comparative Example 5, all the carbon materials used this time were mixed. In Example 5, where the weighted average of VM was 12.6%, 100 tests were possible and the dust could be removed by hammering. On the other hand, in Comparative Example 5 in which the weighted average VM was 9.7%, although the test could be performed 100 times, it was difficult to remove the dust by hammering.

[0045] Industrial Applicability

[0046] The carbon material used in the production of sintered ore of the present invention can provide the following carbon material, which is industrially useful. This carbon material can prevent failures in the exhaust system caused by exhaust treatment, such as tar generation in the piping and white smoke generation in the electric dust collector, by being used in the production of sintered ore.

[0047] Description of Reference Numerals

[0048] 1 Sintered ore manufacturing equipment

[0049] 2 drum mixer

[0050] 3 Sintering machine

[0051] 4 Crusher

[0052] 5 Cooler

[0053] 6 Screening device

[0054] 11 Raw material supply device

[0055] 12 Sintering trolley

[0056] 13 Ignition furnace

[0057] 14 Bellows

Claims

1. A carbon material used in sintered ore production, which is a carbon material used as a solid fuel for sintered ore production, characterized in that: The conductivity is 1.0×10 -9 S / m or more, and the volatile matter (VM) is 15% or less.

2. The carbon material for use in sintered ore production according to claim 1, wherein When the carbon material includes a plurality of carbon materials, the electrical conductivity of the plurality of carbon materials including 80% or more is 1.0×10 -9 The carbon material has an S / m or higher, and a weighted average value of volatile matter (VM) of 15% or less.

3. The carbon material for use in sintered ore production according to claim 1 or 2, characterized in that The carbon material includes a carbon material having a combustion start temperature of 550° C. or less.

4. The carbon material for use in sintered ore production according to claim 3, wherein: The carbon material having a combustion start temperature of 550° C. or less is coke made from biomass carbon, anthracite, waste plastic carbon, lignite and / or sub-bituminous coal.

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