Refractory for melting furnace wall

Abstract

The refractory for a melting furnace wall according to an embodiment of the present invention comprises: 70-85 wt% Al2O3; 3-15 wt% SiC; and 5-15 wt% C.

Description

Refractories for furnace walls of melting furnaces

[0001] One embodiment of the present invention relates to a refractory material for the furnace wall of a melting furnace. More specifically, one embodiment of the present invention relates to a refractory material used as an interior brick in an electric smelting furnace.

[0002] Electric arc furnaces have primarily been used for melting reduced iron; however, due to equipment limitations, the use of high-grade reduced iron with a high iron content has been required. Nevertheless, high-grade iron ore presents problems, such as the need for prior beneficiation or, as a high-cost product, causing cost increases.

[0003] Accordingly, in order to establish a sustainable electric arc furnace process, it is necessary to develop a melting process utilizing low-grade iron ore. Low-grade iron ore refers to iron ore with an iron content of less than 62%, and high-grade iron ore refers to iron ore with an iron content of 62% or more.

[0004] As a method for producing reduced iron by reducing low-grade iron ore, there are shaft reduction furnaces and fluidized bed reduction furnaces. The shaft reduction furnace method is, for example, MIDREX TM ) method, Energyiron TM There are methods such as the ) method. In terms of equipment technology, the fluidized bed reduction furnace method is advantageous for controlling the furnace temperature compared to the shaft reduction furnace method. If the heat in the reduction furnace becomes insufficient, iron ore undergoes poor reduction, making furnace temperature control technology very important in hydrogen reduction steelmaking.

[0005] While reduction reactions using fossil fuels (e.g., coal, natural gas, etc.) are exothermic, hydrogen is an endothermic reaction that absorbs ambient heat upon contact with iron ore; consequently, the heat inside the reduction furnace is easily depleted. Therefore, to prevent a drop in the furnace's temperature, it is necessary to continuously supply heat to the furnace.

[0006] In the case of a fluidized reduction furnace, heat for the reduction furnace is supplied through high-temperature hydrogen reducing gas heated by the heat of reaction with oxygen. The fluidized reduction furnace consists of a multi-stage reduction furnace in which several reactors are arranged in a stepped configuration. The interior of the reactor can be heated by introducing oxygen into at least some or each of the reactors, or by heating the bottom or walls of the reactors. The gas (heated hydrogen gas) introduced into the reactor can be introduced at a temperature of about 900°C or lower. The interior of the reactor can be heated not only by hydrogen gas but also by heating the bottom or walls.

[0007] In contrast, in the case of a shaft reduction furnace, it consists of a single reduction furnace, and the temperature of the entire reduction furnace must be controlled solely by the heat of the reduction gas injected from the bottom. Consequently, in a shaft reduction furnace, the temperature at the top of the reduction furnace tends to drop, and the injection of a high-temperature reduction gas of about 1000°C or higher is required.

[0008] In a reduction furnace, iron oxide can be reduced and converted into reduced iron. Reduced iron may be referred to as sponge iron. Reduced iron can be charged into an electric furnace in powder form or in agglomerated form. Reduced iron in powder form can be produced in a fluidized reduction furnace. Specifically, the ash powder charged into the fluidized reduction furnace has a particle size of 8 mm or less (excluding 0 mm), and such ash powder can be produced into reduced iron in powder form through fluidized reduction. Reduced iron in powder form may have a particle size of 8 mm or less, but is not limited thereto. The raw materials flowing in the fluidized reduction furnace may collide with each other and be crushed into smaller sizes. Accordingly, the average particle size calculated from the raw materials prior to charging into the fluidized reduction furnace may be larger than the average particle size of the reduced iron.

[0009] Meanwhile, the massive method may include a high-temperature molding method. Massive reduced iron source can be manufactured by mixing pulverized reduced iron with anaerobic limestone and pulverized muscovite. The mixture of pulverized reduced iron, anaerobic limestone, and pulverized muscovite can be manufactured by compression molding at high temperatures.

[0010] The reduced iron produced in this way (e.g., powdered reduced iron or bulk reduced iron) is charged into a Smelting Reduction Furnace (ESF).

[0011] A molten reduction furnace melts raw materials in a reducing atmosphere. The molten reduction furnace is an electric molten reduction furnace comprising a plurality of electrode rods. The molten reduction furnace can melt reduced iron, for example, by using a brush arc formed by a plurality of electrode rods. The molten reduction furnace can also melt reduced iron, for another example, by using heat generated by a plurality of electrode rods that are at least partially immersed in slag.

[0012] One embodiment of the present invention relates to a refractory material for the furnace wall of a melting furnace. More specifically, one embodiment of the present invention aims to provide a refractory material used as an interior brick in an electric smelting furnace.

[0013] A refractory material for the furnace wall of a melting furnace according to one embodiment of the present invention comprises Al2O3: 70 to 85 weight%, SiC: 3 to 15 weight%, and C: 5 to 15 weight%.

[0014] A refractory material for the furnace wall of a melting furnace according to one embodiment of the present invention comprises Al2O3: 79 to 83 weight%, SiC: 3 to 8 weight%, and C: 9 to 14 weight%.

[0015] A refractory material for the furnace wall of a melting furnace according to one embodiment of the present invention may further include one or more of CaO and MgO in a combined amount of 5% by weight or less.

[0016] The refractory material can be reduced in length to 9 mm or less by contacting it with molten slag at a temperature of 1400 to 1600°C for 1 hour.

[0017] The refractory material can be reduced in length to 10 mm or less by contacting molten iron at a temperature of 1400 to 1600°C for 48 hours.

[0018] The refractory material can be reduced in length to 15 mm or less by contacting molten slag at a temperature of 1400 to 1600°C for 48 hours.

[0019] A refractory material for a furnace wall of a melting furnace according to one embodiment of the present invention has excellent corrosion resistance and slow erosion, and has a long lifespan.

[0020] In this specification, terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the invention.

[0021]

[0022] In this specification, when a part is described as "comprising" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0023] In this specification, technical terms used are intended merely to refer to specific embodiments and are not intended to limit the invention. Singular forms used herein include plural forms unless phrases clearly indicate otherwise. The meaning of "comprising" as used in this specification specifies a particular characteristic, area, integer, step, action, element, and / or component, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0024] In this specification, the term “combination thereof” included in a Markush-type expression means one or more mixtures or combinations selected from a group consisting of components described in the Markush-type expression, and means including one or more selected from the group consisting of said components.

[0025] In this specification, when a part is referred to as being "on" or "on" another part, it may be immediately on or on the other part, or other parts may be involved between them. In contrast, when a part is referred to as being "immediately on" another part, no other parts are interposed between them.

[0026] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0027] Also, unless otherwise specified, % refers to weight %.

[0028] In one embodiment of the present invention, the meaning of including additional elements is that the remainder of iron (Fe) is replaced by an amount of the additional element.

[0029] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0030]

[0031] One embodiment of the present invention relates to a refractory material for the furnace wall of a melting furnace. More specifically, one embodiment of the present invention relates to a refractory material used as an interior brick in an electric smelting furnace.

[0032] The refractory structure of the ESF includes a permanent lining. The permanent lining is installed in the electric furnace to prevent damage to the outer shell or molten iron leakage that may occur due to damage to the working lining (which can be mixed with the working bricks). The permanent lining is installed on the outer side of the refractory structure. The permanent lining is located on the outer side of the semi-permanent lining. The permanent lining can enclose the semi-permanent lining.

[0033] The inner side of the semi-permanent wall is made of interior bricks, and a refractory material according to one embodiment of the present invention can be used in these interior bricks.

[0034]

[0035] A refractory material for the furnace wall of a melting furnace according to one embodiment of the present invention comprises Al2O3: 70 to 85 weight%, SiC: 3 to 15 weight%, and C: 5 to 15 weight%.

[0036] Below, each component is explained in detail.

[0037] Al2O3: 70 to 85 wt%

[0038] Alumina (Al2O3) is added to maintain a high degree of refractoriness of the refractory material. If too little Al2O3 is added, thermal shock resistance may be compromised. If too much Al2O3 is added, the SiC and C content may be relatively reduced, making it difficult to obtain sufficient corrosion resistance improvement effects along with the grazing effect. More specifically, Al2O3 may be included in an amount of 78.0 to 83.0 weight%.

[0039] The average particle size of Al2O3 can be 1 mm or less.

[0040] SiC: 3 to 15 wt%

[0041] Silicon carbide (SiC) is added to control the penetration of foreign substances and for grazing effects. If too little SiC is added, it is difficult to obtain the above effects sufficiently. If too much SiC is added, in a high-temperature operating environment, SiC comes into contact with slag and facilitates the formation of ternary low-melting point compounds Monticellite (CaMgSiO4) and Gehlenite (Ca2AlSiO), which may lead to a decrease in corrosion resistance. More specifically, SiC may be included in an amount of 3 to 8 weight percent.

[0042] The average particle size of SiC can be 1 mm or less.

[0043] C: 5 to 15 weight%

[0044] When carbon (C) is added, it is possible to control the penetration of foreign substances and achieve a grazing effect, along with improved corrosion resistance. Although C may cause liquid-phase oxidation in the molten metal, increasing the carbon content of the refractory material actually helps improve corrosion resistance. If too little C is included, the improvement in corrosion resistance may not be sufficient. If too much C is included, the carbon oxidizes, and slag and molten iron penetrate into the empty areas, which can accelerate the erosion of the refractory material. More specifically, C may be included in an amount of 9 to 14 weight percent.

[0045] The average particle size of C can be 0.075 to 1.000 mm.

[0046] C may include one or more of carbon black, pitch powder, crushed artificial graphite, and coke particles.

[0047]

[0048] A refractory material for the furnace wall of a melting furnace according to one embodiment of the present invention further comprises one or more of CaO and MgO in an amount of 5% by weight or less as a total. When one or more of CaO and MgO are additionally included, corrosion resistance can be further improved.

[0049]

[0050] In one embodiment of the present invention, excellent corrosion resistance and slow erosion progression result in a long lifespan.

[0051] The refractory material may be reduced in length to 9 mm or less by contacting molten slag at a temperature of 1400 to 1600°C for 1 hour. At this time, the basicity of the molten slag may be 1.0 to 2.5. The erosion test may be conducted at a speed of 100 rpm. More specifically, when the basicity of the molten slag is 1.5, the length may be reduced to 7.0 mm or less. More specifically, the length may be reduced to 3.5 to 5.0 mm. More specifically, when the basicity of the molten slag is 2.0, the length may be reduced to 5.0 mm or less. More specifically, the length may be reduced to 2.0 to 3.3 mm.

[0052] The refractory material may be reduced in length to 10 mm or less by contacting molten iron at a temperature of 1400 to 1600°C for 48 hours. More specifically, it may be 2 to 10 mm.

[0053] The refractory material can be reduced in length to 15 mm or less by contacting molten slag at a temperature of 1400 to 1600°C for 48 hours. More specifically, when the basicity of the molten slag is 1.2, the refractory material can be reduced in length to 5 to 14 mm or less by contacting the molten slag.

[0054]

[0055] The present invention will be explained in more detail below through examples. However, it should be noted that the following examples are intended merely to illustrate and explain the invention in more detail, and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[0056]

[0057] Experimental Example 1

[0058] Refractory bricks containing CaO and MgO as the remaining additive components and the components in Table 1 below were manufactured, and the slag basicity was set to 1.5. An erosion test was conducted at a speed of 100 rpm for 1 hour at a molten slag and molten iron temperature of 1550℃ to evaluate the results. Corrosion resistance was evaluated as O (excellent) if the erosion length was 5.0 mm or less, and △ (poor) if it exceeded 5.0 mm.

[0059] Al2O3 (wt%) SiC (wt%) C (wt%) Erosion Length (mm) Corrosion Resistance Example 1 72.5 13.0 11.0 6.20 △ Example 2 75.5 10.0 11.0 5.45 △ Example 3 81.5 4.0 11.0 4.24 ○ Example 4 80.0 4.0 12.5 4.20 ○ Example 5 78.5 4.5 13.5 4.42 ○ Example 6 80.5 5.0 11.0 6.99 △ Comparative Example 1 MgO: 82.4 wt%, C: 12.1 wt% 8.00 △

[0060] As shown in Table 1, it can be confirmed that the erosion length is short for refractories in which each component is appropriately controlled. In particular, it can be confirmed that Examples 3 to 5 are even more superior.

[0061]

[0062] Experimental Example 2

[0063] The experiment was conducted in the same manner as Experimental Example 1, except that the slag basicity was set to 2.0, and the erosion test was evaluated by conducting the test at a speed of 100 rpm for 1 hour at a molten slag and molten iron temperature of 1500℃. Corrosion resistance was indicated based on an erosion length of 3.0 mm.

[0064] Al2O3 (wt%) SiCC Erosion Length (mm) Corrosion Resistance Example 275.5 10.0 11.0 3.5 △ Example 381.5 4.0 11.0 3.0 ○ Example 480.0 4.0 12.5 2.6 ○ Example 578.5 4.5 13.5 3.9 △ Example 680.5 5.0 11.0 4.8 △

[0065] As shown in Table 2 above, it can be confirmed that the erosion length is short for refractories in which each component is appropriately controlled. In particular, it can be confirmed that Examples 3 and 4 are superior in terms of corrosion resistance.

[0066] Experimental Example 3

[0067] As refractory bricks in contact with molten iron and slag in an electric melting reduction furnace, the refractory material of Example 3 was installed at slag line position 3 (tap hole and 90° and 270° to the right of the tap hole) and molten iron line position 3 (tap hole and 90° and 270° to the right of the tap hole), the slag basicity was set to 1.2 and the molten iron temperature was maintained at 1400 to 1500°C, and continuous operation was carried out for 48 hours to measure the erosion length of the refractory material.

[0068] Erosion Length (mm) Slag Line 19 Slag Line 214 Slag Line 37 Molten Iron Line 110 Molten Iron Line 24 Molten Iron Line 32

[0069] As shown in Table 3, it can be confirmed that the erosion length is not long even when in contact with molten slag and molten iron.

[0070]

[0071] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Refractory for a furnace wall of a melting furnace comprising Al2O3: 70 to 85 wt%, SiC: 3 to 15 wt%, and C: 5 to 15 wt%.

2. In Paragraph 1, Refractory for a furnace wall of a melting furnace comprising Al2O3: 79 to 83 wt%, SiC: 3 to 8 wt%, and C: 9 to 14 wt%.

3. In Paragraph 1, Refractory material for the furnace wall of a melting furnace further containing one or more of CaO and MgO in a combined amount of 5% by weight or less.

4. In Paragraph 1, The above refractory material is a refractory material for the furnace wall of a melting furnace that is reduced in length to 9 mm or less by contacting molten slag at a temperature of 1400 to 1600℃ for 1 hour.

5. In Paragraph 1, The above refractory material is a refractory material for the furnace wall of a melting furnace that is reduced in length to 10 mm or less by contacting molten iron at a temperature of 1400 to 1600°C for 48 hours.

6. In Paragraph 1, The above refractory material is a refractory material for the furnace wall of a melting furnace that is reduced in length to 15 mm or less by contacting molten slag at a temperature of 1400 to 1600°C for 48 hours.