Method for producing sintered ore and method for using silicic acid biomass for blast furnace

Abstract

The present invention provides a method for producing a sintered ore and a method for using a silicic acid biomass for a blast furnace, the methods utilizing biochar that is derived from a silicic acid biomass. The present invention relates to a method for producing a sintered ore by a Dwight-Lloyd sintering machine, and uses a granulated starting material that is obtained by blending a powdery iron ore, a component adjusting flux, a return ore, and a carbonaceous material. Fixed carbon and silicon oxide in the biochar that is obtained by subjecting a silicic acid biomass to a dry distillation treatment are applied to some or all of the carbonaceous material and some or all of the silicon oxide content in the component adjusting flux to be blended in the granulated starting material. In this method for using a silicic acid biomass for a blast furnace, a sintered ore which is obtained as described above is charged from the furnace top of the blast furnace.

Description

Sintered ore manufacturing method and method for utilizing silica biomass in a blast furnace

[0001] The present invention relates to a method for producing sintered ore and a method for utilizing silica biomass in a blast furnace.

[0002] In blast furnace operation, it is extremely important to adjust the basicity of the slag in the blast furnace and ensure the fluidity of the slag in order to smoothly promote the reaction in the blast furnace. The sinter used to produce slag in this blast furnace is made of iron ore as the main raw material and SiO2 such as silica. ２ It is produced by sintering a granulated raw material obtained by mixing and granulating a mixture of a CaO-based auxiliary material, a CaO-based auxiliary material such as limestone, sintered ore return ore of a size smaller than a predetermined size, and a carbonaceous material such as coke fines. The auxiliary materials blended in the production of such sintered ore are used to adjust the sinterability of the sintered ore. In addition, the auxiliary materials are used as gangue components of the sintered ore and as a supply source of blast furnace slag, thereby increasing the fluidity of the slag in the blast furnace. For example, in Patent Document 1, SiO ２ and / or an auxiliary material containing MgO in an amount of 1.5 to 6 wt % of the granulated raw material to form pseudo-particles, which are then charged into the lowest layer of the sintering raw material on a sintering pallet. ２ Furthermore, this invention is said to be able to maintain smooth blast furnace operation without lowering the furnace top temperature.

[0003] On the other hand, from the perspective of preventing global warming, ２ Reducing CO emissions is an urgent issue, and the steel industry is also ２ Technology development is underway to reduce CO emissions. ２ There are two ways to reduce emissions: (a) reducing the amount of carbon in the input, and (b) reducing the amount of CO2 in the output. ２ (c) Replacing conventional coal, oil, etc. with carbon-free carbon sources.

[0004] In a conventional downward suction type sintering machine such as a Dwight Lloyd type sintering machine, a large amount of coal (anthracite) or coke breeze is used as the carbonaceous material, which generates a large amount of carbon dioxide gas. In response to this problem, Patent Document 2 discloses an invention that uses biochar, such as oil palm kernel shell charcoal, as a carbon-free carbon source for the carbonaceous material during sintering.

[0005] Japanese Patent Application Laid-Open No. 08-085829 Japanese Patent Application Laid-Open No. 2013-237876

[0006] Meanwhile, the expanded use of biomass (also called silicic acid biomass due to its high ash content), such as rice husks and straw, which are carbon-free carbon sources and are generated in Japan in amounts exceeding 2 million tons annually, has become a problem. This is because biochar derived from silicic acid biomass can be problematic due to its high ash content of approximately 30-50%. Furthermore, biochar derived from silicic acid biomass not only promises stable supply, but also possesses sufficient properties as a carbon source, with a fixed carbon content of approximately 15-50% and a unit calorific value of approximately 14-28 MJ / kg.

[0007] Previous studies of biochar as a carbon-free carbon source in steelworks have not adequately addressed the issue of high ash content in biochar derived from silicate biomass. Patent Document 2, which describes the use of biochar in a sintered ore production process, also fails to explicitly address the issue of high ash content in biochar derived from silicate biomass. The biochar described in this document is oil palm kernel shell charcoal, and the major components of the biochar exemplified in this document are 81.0-89.5% by mass fixed carbon, 7.2-9.2% by mass ash, and 3.2-9.8% by mass volatile matter. In contrast, the data disclosed in this document for the target coke breeze are 86.0% by mass fixed carbon, 12.9% by mass ash, and 1.1% by mass volatile matter. The target anthracite coal has 88.5% by mass fixed carbon, 5.0% by mass ash, and 6.4% by mass volatile matter. This is probably because the component composition of oil palm kernel shell coal is the same as that of its substitutes, coke breeze and anthracite, and there is no need to particularly address the issue of ash content.

[0008] On the other hand, it remains to be determined whether biochar derived from silicic acid biomass with a high ash content can be used as is as the carbonaceous material in the granulated raw material for the sintering raw material to be made into pseudo-particles as described in Patent Document 1. This is because if biochar derived from silicic acid biomass is used as a heat source for sintering in the production of sintered ore, its high ash content would directly affect the adjustment of blast furnace slag basicity and slag fluidity, which are the objectives of Patent Document 1.

[0009] Therefore, an object of the present invention is to provide a method for producing sintered ore that utilizes biochar derived from silicate biomass and a method for using silicate biomass in a blast furnace.

[0010] [1] A method for producing sintered ore using a Dwight Lloyd sinter machine with a granulated raw material blended with fine iron ores, a composition-adjusting sintering material, return ore, and a carbonaceous material, in which some or all of the carbonaceous material and some or all of the silicon oxide content of the composition-adjusting sintering material are replaced with fixed carbon and silicon oxide in biochar obtained by carbonizing silicic acid biomass. [2] A method for utilizing silicic acid biomass in a blast furnace, in which sintered ore produced using a granulated raw material blended with fine iron ores, a composition-adjusting sintering material, return ore, and a carbonaceous material, in which some or all of the carbonaceous material and some or all of the silicon oxide content of the composition-adjusting sintering material are replaced with fixed carbon and silicon oxide in biochar obtained by carbonizing silicic acid biomass, is charged into the top of a blast furnace.

[0011] According to the present invention, part or all of the carbonaceous material in the granulated raw material is replaced with fixed carbon in biochar derived from silicate biomass, thereby reducing CO ２ Furthermore, according to the present invention, a part or all of the silicon oxide content of the composition-adjusted welding material in the granulation raw material is directly replaced by the silicon oxide in the biochar derived from silicic acid biomass, so there is no adverse effect on the basicity of the melt during sintering or the basicity of the melt in the blast furnace. Furthermore, according to the present invention, the carbonaceous material in the granulation raw material and the SiO ２By using biochar derived from silicic acid biomass, which is produced in large quantities in Japan every year, as a raw material that also contains silicon dioxide-based auxiliary materials, there is an advantageous effect in terms of procurement. On the other hand, according to the present invention, it is possible to provide a new application for biochar derived from silicic acid biomass, which has previously had limited uses due to its high ash content, by effectively utilizing both fixed carbon and silicon oxide at the same time. As described above, according to the present invention, the procurement of biochar and CO2 reduction in the steel industry can be improved without adversely affecting the sintering reaction during sintering or the basicity of blast furnace slag. ２ It is possible to provide a method for producing sintered ore and a method for using silica biomass in a blast furnace, which contribute to reducing emissions.

[0012] 1 is a flowchart illustrating a method for producing sintered ore according to an embodiment of the present invention.

[0013] The sintered ore according to the embodiment of the present invention is one of the raw materials charged into the top of a blast furnace. Iron ore as a blast furnace raw material can be efficiently used in various forms, such as lump ore that can be charged as is, or by changing the form depending on the state of the raw material. For example, fine ore that would otherwise impair the air permeability inside the furnace can be sintered to form sintered ore, or iron-containing dust recovered in a steelworks can be agglomerated with hydraulic cement to form unsintered agglomerated ore.

[0014] As shown in Figure 1, sintered ore according to an embodiment of the present invention is produced in a Dwight Lloyd sintering machine using a granulated raw material containing fine iron ores, a composition-adjusted sintering material, return ore, and a carbonaceous material. In this process, some or all of the carbonaceous material and some or all of the silicon oxide content of the composition-adjusted sintering material are replaced with fixed carbon and silicon oxide in biochar obtained by carbonizing silicic acid biomass. Another embodiment of the present invention is a method for utilizing silicic acid biomass in a blast furnace, in which the sintered ore produced in this manner is charged into the top of the blast furnace. Here, the method for producing sintered ore according to this embodiment and the method for utilizing silicic acid biomass in a blast furnace according to other embodiments will be described together without distinction.

[0015] The method for producing sintered ore according to the embodiment of the present invention is essentially the same as a conventional method for producing sintered ore, except that biochar obtained by dry distillation of silicate biomass is used to replace the silicon oxide content of the carbonaceous material and the composition-adjusting melting material used as granulation raw materials. Therefore, the conventional method for producing sintered ore, which is the premise of this embodiment, will be described first.

[0016] As shown in Figure 1, the raw material for sintered ore is prepared by blending fine iron ore, a composition-adjusted solder, return ore (sintered ore powder of a size that cannot be used as a blast furnace feedstock), and carbonaceous material. The blend is then granulated in a drum mixer while adjusting the moisture content to form pseudo-particles, which are then sintered. By converting the granulated raw material, the raw material for sintered ore, into pseudo-particles, the permeability of the pseudo-particles can be improved when the pseudo-particles are loaded into a sintering machine, such as a Dwight Lloyd sintering machine, and sintering proceeds smoothly. These pseudo-particles are composed of core particles of granulated raw material, primarily granular iron ore with a particle size of approximately 10 mm to 1 mm. These pseudo-particles are composed of core particles surrounded by powder particles such as fine iron ore, composition-adjusted solder, sintered ore powder (return ore), and coke powder, each with a particle size of 1 mm or less, which adhere to the core particles due to added moisture. Fine iron ore refers to iron ore powder, iron-containing dust, scale, and other raw materials that contain a large amount of iron. In order to average out the different component compositions of iron ore from each mine, the iron ore in the iron ore fines is usually blended with a plurality of fine ores. The component adjustment materials are mainly CaO-based auxiliary materials such as limestone, and SiO2-based materials consisting of silica stone and various smelting slags. ２ The carbonaceous material is the fuel for the combustion reaction during sintering, and anthracite, coke powder, etc. are used.

[0017] This pseudo-granulated sinter raw material is charged onto a pallet in a moving grate sinter machine, and a burner in an ignition furnace on the inlet side ignites the carbonaceous material such as coke present on the surface of the packed bed. In a bottom suction type sinter machine, air is sucked from above the packed bed and passed downward, and the heat of combustion of the carbonaceous material is transferred from the upper layer to the lower layer, progressing the sintering process, which is completed when the pallet moves to the outlet side of the sinter machine. The resulting sinter cake is crushed and sized to produce sintered ore with an average particle size of 3 to 5 mm.

[0018] The main component composition of the granulated raw material to be sintered is usually T. Fe: 55 to 57 mass%, CaO: 9 to 10 mass%, SiO ２ :5 to 5.3% by mass, Al ２ O ３ : 1.7 to 1.8 mass%, MgO: 1% to 20 mass%. The amount of carbonaceous material added as a heat source is about 5 mass% of the granulated raw material. When the sintered raw material with such a component composition is heated and sintered, it is first heated to about 1200°C to separate CaO and iron oxide Fe. ２ O ３ reacts to generate an initial melt. Then, as the temperature rises, SiO ２ , Al ２ O ３ Gangue (slag) components such as MgO and iron oxide melt (assimilate) in the molten liquid, and the coarse iron ore particles are bonded together through this molten liquid, resulting in sintering.

[0019] As mentioned above, the main reaction in the sintering reaction is the sintering of Fe in iron ore. ２ O ３ The initial melt is generated by the reaction of the iron ore with the CaO in the limestone, and the melt reacts with the auxiliary materials and SiO ２ This is a melting reaction of gangue components such as iron oxide and iron oxide, which is called an assimilation reaction. For example, if the assimilation reaction proceeds excessively and the amount of melt generated increases dramatically, uneven sintering occurs due to poor permeability in the sintered layer, significantly reducing the yield and strength. On the other hand, if the assimilation reaction does not proceed, the melt that bonds unmelted iron ore particles together decreases, causing a decrease in the product yield and the strength of the sintered ore. Such a sintering reaction occurs due to the basicity CaO / SiO of the melt generated during sintering caused by the component-adjusting flux in the granulation raw material. ２ can be controlled by managing it within a predetermined range.

[0020] The method for producing sintered ore according to this embodiment is to determine the basicity of the melt produced during sintering, CaO / SiO ２ The SiO in the component adjusting solvent blended in the granulation raw material is related to the means for controlling the SiO in the component adjusting solvent blended in the granulation raw material. ２ The silicon oxide in biochar derived from silicic acid biomass is used as the secondary raw material. ２The predetermined range is, for example, 1.0 or more and 2.0 or less. At the same time, in this embodiment, the fixed carbon contained in the biochar derived from silicic acid biomass together with the silicon oxide is also used as a carbonaceous material that is blended with the granulation raw material and used as a heat source.

[0021] In the biochar derived from silicic acid biomass according to the present embodiment, the fixed carbon as the carbonaceous material and the silicon oxide as the silicon oxide component of the composition-adjusting flux are already mixed together, but this does not pose any problems. The biochar derived from silicic acid biomass according to the present embodiment can also be mixed with other granulated raw materials such as fine iron ore by going through the steps of a conventional method for producing sintered ore.

[0022] Silica biomass refers to plants containing silica (silica plants) or parts thereof such as their leaves and stems, and includes rice husks and straw from plants such as rice and wheat, bamboo leaves, and corn leaves and stems. Biochar derived from silica biomass is a carbonaceous material obtained by dry distillation of silica biomass, and can be obtained by any dry distillation method, but dry distillation using a rotary kiln is an example. As mentioned above, biochar derived from silica biomass has a fixed carbon content of approximately 15 to 50% by mass, an ash content of approximately 30 to 50% by mass, and a unit calorific value of approximately 14 to 28 MJ / kg.

[0023] The carbonaceous material in the granulated raw material that is the sintering raw material related to this embodiment, which is to be replaced with fixed carbon in biochar derived from silicic acid biomass in this embodiment, is the same anthracite pulverized coal and coke breeze that are generally used in the production of sintered ore. In this embodiment, a part or all of these are replaced with fixed carbon in biochar derived from silicic acid biomass and used as the carbonaceous material. The fixed carbon in biochar derived from silicic acid biomass used here is a carbon-free carbon source, and it is used to replace the CO2 generated by the coal-derived carbonaceous material before replacement. ２ This has the effect of reducing emissions.

[0024] In the operation of a blast furnace, ensuring the air permeability and liquid permeability around the cohesive zone is one of the most important management issues. ２The amount of the composition-adjusting melt in this embodiment is adjusted by increasing or decreasing the amount of the auxiliary raw materials such as limestone and silica stone that are mixed with the raw materials such as iron ore so that the basicity CaO / SiO of the melt in the blast furnace falls within a predetermined range. ２ Therefore, it is preferable to adjust the basicity of the melt during the assimilation reaction of the sintered ore, while giving priority to the adjustment of the basicity of the melt in the blast furnace.

[0025] Basicity of the entire sintering raw material (CaO / SiO ２ The adjustment of the amount of CaO and SiO contained in each of the fine iron ores and the composition-adjusted melting material is carried out by ２ This can be achieved by adjusting the blending pattern of each raw material so that the basicity calculated from the total amount of each raw material falls within a predetermined range.

[0026] In this embodiment, a part or all of the silicon oxide content of the composition-adjusted welding material is replaced with silicon oxide in biochar derived from silicic acid biomass without changing the silicon oxide content of the entire sintered ore. Therefore, even if biochar derived from silicic acid biomass is used for sintering, it does not adversely affect the assimilation reaction during the production of sintered ore.

[0027] In the method for producing sintered ore according to this embodiment, a specific preferred embodiment that maximizes the use of biochar derived from silicic acid biomass will be described. First, because the fixed carbon and silicon oxide amounts per unit amount of biochar derived from silicic acid biomass are expected to fluctuate, the fixed carbon and silicon oxide amounts per unit amount of the incoming biochar derived from silicic acid biomass are confirmed. Next, of the confirmed fixed carbon and silicon oxide amounts, if any of the blended raw materials can be fully used as a blended raw material for the granulated raw material to be sintered, the blended raw material ratio is determined by completely substituting the remaining blended raw material, and partially substituting the remaining blended raw material. It goes without saying that in this embodiment, the fixed carbon and silicon oxide amounts of the biochar derived from silicic acid biomass may be partially used as a blended raw material for the sintered ore.

[0028] Here, carbonaceous materials in the usual granulated raw materials that are used as sintering raw materials and SiO２ This paper explains the results of calculations for the equivalent replacement of the secondary raw materials with fixed carbon and silicon oxide in biochar derived from silicic acid biomass.

[0029] In addition, as the raw materials to be blended into the normal granulated raw material, which is the sinter raw material on the premise of the calculation, mixed iron ore is assumed as fine iron ore, and limestone and silica stone are assumed as component adjusting materials. In addition, the silicon oxide content and SiO2 for calculating the basicity of the entire granulated raw material, which are the subject of the calculation, are assumed to be mixed iron ore as fine iron ore, and limestone and silica stone are assumed as component adjusting materials. ２ Strictly speaking, the contents of iron ore fines and return ore must also be taken into account for CaO, but for simplicity, the calculations were made based only on the raw materials for the composition-adjusted sintering material. Also, carbonaceous materials are consumed as a heat source for sintering and do not remain in the final sintered ore product, so they are shown as separate amounts relative to the other granulation raw materials.

[0030] The components and overall properties of the normal granulated raw material used as the sintering raw material for the specific calculations are as follows: Fine iron ore (mixed iron ore): 58.1% by mass; Component adjustment materials (the following two types): Limestone: 17.9% by mass; Silica: 5.0% by mass; Return ore: 19.0% by mass; Carbon material (coke fines) (excluding): 4.0% by mass; Overall properties of the granulated raw material: Basicity CaO / SiO ２ : 2.0

[0031] The biochar derived from silicate biomass was rice husk charcoal dry-distilled at 500°C, and had the following components: fixed carbon: 28% by mass, volatile matter: 35% by mass, ash: 38% by mass (including SiO ２ :34% by mass)

[0032] Under the above preconditions, 40 kg of carbonaceous material and silica stone (SiO ２ If we first try to use the fixed carbon in biochar to replace 40 kg of the carbon material, the amount of biochar required is 143 kg. Biochar to replace carbon material: 40 (kg) / 28 (%) = 143 (kg). In this case, the SiO in biochar ２ 49 kg of SiO will be mixed at the same time, but including the error, ２The required amount of 50 kg, and basicity CaO / SiO ２ This is equivalent to 2.0, and it is clear that biochar can be used. ２ : 143 (kg) × 34 (%) = 49 (kg) CaO in limestone: 179 (kg) × 56 (%) = 100 (kg) Basicity CaO / SiO ２ :100(kg) / 49(kg)=2.0

[0033] Just to be sure, 40 kg of carbon material and silica stone (SiO ２ ) out of 50 kg, we estimated the case where all 50 kg of silica was replaced with the silicon oxide content of biochar, but the results were the same as when the fixed carbon in biochar was used instead of the carbon material. ・Biochar replacing silica: 50 (kg) / 34 (%) = 147 (kg) In this case, 41 kg of fixed carbon in biochar is also mixed in at the same time, which means that almost the entire amount of 40 kg of carbon material required for replacement can be used. ・Fixed carbon mixed in at the same time: 147 (kg) x 28 (%) = 41 (kg)

Claims

1. A method for producing sintered ore using a Dwight Lloyd sintering machine, which uses a granulated raw material that is a blend of fine iron ore, a composition-adjusting sintering material, return ore, and a carbonaceous material, and in which part or all of the carbonaceous material and part or all of the silicon oxide content of the composition-adjusting sintering material are replaced with fixed carbon and silicon oxide in biochar obtained by dry distillation of silicate biomass.

2. A method for utilizing silica biomass in a blast furnace, comprising charging sintered ore produced from a granulated raw material containing a blend of fine iron ores, composition-adjusted solder, return ore, and carbonaceous material, in which part or all of the carbonaceous material and part or all of the silicon oxide content of the composition-adjusted solder are replaced with fixed carbon and silicon oxide in biochar obtained by carbonizing silica biomass, into the top of a blast furnace.

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