How to repair an electric furnace

Abstract

To provide a repairing method for an electric furnace capable of reducing an amount of the refractory disposed of when repairing the electric furnace.SOLUTION: A repairing method for an electric furnace is designed to repair a worn part which has occurred in the lining refractory of a furnace body after repeated operations in an electric furnace for melting an iron source. This method includes a step of filling the worn part with a repairing refractory having fluidity, followed by a step of heating the furnace body by a heat source of the electric furnace to sinter the refractory for repair.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for repairing an electric furnace. [Background technology]

[0002] Electric furnaces for melting iron sources are constructed with a steel shell lined with refractory material, and the refractory lining is worn away by heat during repeated operation, requiring repair. Conventionally, when repairing an electric furnace, it has been common to dismantle and remove the refractory material worn away by heat, and then build a new furnace using new refractory material (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-240587 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with this technology, the refractory materials that are dismantled and removed must be disposed of, generating a large amount of industrial waste, which has a negative impact on the environment and is economically inefficient.

[0005] Therefore, an object of the present invention is to provide a method for repairing an electric furnace that can reduce the amount of refractory material discarded when repairing an electric furnace. [Means for solving the problem]

[0006] The present invention provides the following (1) to ( 4 ) provides a means for

[0007] (1) A repair method for an electric furnace for melting an iron source, in which, when a worn portion occurs in the refractory lining of the furnace body due to repeated operation, the worn portion is repaired, The repair refractory material having flowability to the damaged portionThings a filling step; Next, a step of heating the furnace body with a heat source of the electric furnace to sinter the repair refractory; have 、 In the step of filling the repair refractory, a mixture of multiple types of silica-based refractories is used as the repair refractory having fluidity so as to ensure sufficient fluidity for filling the worn portion. A method for repairing an electric furnace.

[0008] (2) When the worn portion includes a furnace wall, the step of filling the repair refractory includes setting an iron cylinder member so as to correspond to at least a portion of the inside of the furnace wall including the worn portion, and inserting the fluid repair refractory between the iron cylinder member and the portion including the worn portion. Things The electric furnace repair method according to (1), characterized in that:

[0009] (3) After the electric furnace is repaired by sintering the repair refractory, if a worn portion of the lining refractory is again generated by repeated operation, the Liquidity Repair fireproofing Things and a step of sintering the repair refractory material in the worn portion that has reoccurred. death, In the step of filling the re-occurring worn portion with the repair refractory, a mixture of multiple types of silica-based refractories is used as the repair refractory having fluidity so as to ensure sufficient fluidity for filling the worn portion. The electric furnace repair method according to (1) above,

[0010] (4) The first and second damaged parts , furnace If walls are included, The repair refractory is applied to the initially damaged portion. Things The filling step includes setting a first iron cylinder member so as to correspond to at least a portion of the inside of the furnace wall including the first-occurred worn portion, and disposing the flowable repair refractory material between the first iron cylinder member and the portion including the first-occurred worn portion. Things Supply, The repair refractory material is applied to the re-occurring damaged portion. ThingsThe filling step includes setting a second iron cylinder member so as to correspond to at least a portion of the inside of the furnace wall including the re-occurred worn portion, and disposing the flowable repair refractory material between the second iron cylinder member and the portion including the re-occurred worn portion. Things The electric furnace repair method according to (3), characterized in that: [Effects of the Invention]

[0012] According to the present invention, there is provided a method for repairing an electric furnace that can reduce the amount of refractory waste generated when repairing an electric furnace. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a schematic structure of an electric furnace applied to a method for repairing an electric furnace according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a state in which a worn portion occurs in the electric furnace of FIG. [Figure 3] 1A to 1C are cross-sectional views illustrating steps in a method for repairing an electric furnace according to an embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view showing a state in which an iron cylinder member is set in order to fill a damaged portion of a furnace wall with repair refractory material. [Figure 5] FIG. 5 is a cross-sectional view showing a state in which, after the iron cylinder member is set as in FIG. 4, a portion including a worn portion is filled with repair refractories. [Figure 6] FIG. 6 is a cross-sectional view showing a state in which the furnace body is heated from the state shown in FIG. 5 to sinter the repair refractory material and melt the iron cylinder member. [Figure 7] FIG. 2 is a cross-sectional view showing a state in which a worn portion formed on the hearth of the refractory material is filled with repair refractory material. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a schematic structure of an electric furnace that is applied to a method for repairing an electric furnace according to one embodiment of the present invention. As shown in FIG. 1, the electric furnace 1 has a furnace body 10 and a heat source (not shown). The furnace body 10 is a container for melting an iron source, and has a furnace wall 10a and a furnace bottom 10b. The furnace body 10 is constructed by lining an iron shell 11 with a refractory material 12. A hood 14 is provided at an upper opening 10c of the furnace body 10. The heat source melts the iron source in the furnace body 10, and an induction coil, for example, is used.

[0015] As the electric furnace 1 is repeatedly operated, the refractory lining 12 is worn away by heat, and when a worn portion 15 appears in the refractory 12, which is thinner than a predetermined thickness, as shown in FIG. 2, the electric furnace 1 is repaired.

[0016] Conventionally, when refractory material is worn out by heat, it is common to dismantle and remove the refractory material and build a new furnace using new refractory material, as shown in Patent Document 1. However, the dismantled and removed refractory material must be discarded, generating a large amount of industrial waste, which has a negative impact on the environment and is economically inefficient.

[0017] 3, a fluid repair refractory 16 is filled into the portion including the worn portion 15, and then the furnace body 10 is heated by a heat source (not shown) of the electric furnace 1 to sinter the repair refractory 16 into a sintered refractory 17. The repair refractory 16 is filled in the form of, for example, a fluid powder. As the repair refractory 16, for example, a silica-based refractory can be used.

[0018] As described above, in this embodiment, partial furnace construction is performed by filling the repair refractory 16 having fluidity and sintering the repair refractory 16 without dismantling the portion including the worn portion 15. This makes it possible to reduce the amount of refractory waste generated when repairing an electric furnace, thereby reducing adverse environmental impacts and economic inefficiencies.

[0019] In this embodiment, when the worn portion 15 of the refractory 12 includes the furnace wall 10a as shown in Fig. 2, it may be difficult to fill the worn portion 15 with the repair refractory 16 as it is, so it is preferable to set the iron cylinder member 20 so as to correspond to at least the portion inside the furnace wall 10a including the damaged portion 15, as shown in Fig. 4. Then, as shown in Fig. 5, the repair refractory 16 having fluidity is supplied and filled between the iron cylinder member 20 and the portion including the damaged portion 15.

[0020] The repair refractory 16 is sintered by heating the furnace body 10 with a heat source to a temperature equal to or higher than the melting point of iron, for example, 1600°C or higher. The repair refractory 16 may be sintered during the operation of the electric furnace 1. When the repair refractory 16 is packed using an iron cylinder member 20, by heating the furnace body, the repair refractory 16 is sintered to become a sintered refractory 17, as shown in Fig. 6, and the iron cylinder member 20 is melted to become an iron source.

[0021] As shown in FIG. 7, the worn portion 15 formed on the hearth 10b of the refractory 12 is simply filled with repair refractory 16 without any relation to the iron cylinder member.

[0022] After repairing the electric furnace 1 by the partial construction of this embodiment, repeated operation may cause worn portions to appear again in the refractory 12, requiring repair. In this case, the electric furnace 1 can be repaired by partial construction similar to the conventional method, in which the worn portions are filled with repair refractory and the refilled repair refractory is sintered. By repairing the electric furnace 1 again by partial construction in this way, the refractory is not dismantled and discarded, and the amount of discarded refractory can be further reduced.

[0023] If the renewed damaged portion includes the furnace wall, a second iron cylinder member is set in the furnace wall 10a so as to correspond to at least the portion of the inside of the furnace wall 10a including the renewed damaged portion, and a flowable repair refractory material is supplied between the second iron cylinder member and the portion including the renewed damaged portion. At this time, by appropriately shaping the second iron cylinder member depending on the position and size of the worn portion, it becomes possible to partially rebuild the furnace again.

[0024] When repairing a furnace by partial reconstruction, the damaged parts are filled with repair refractory material, so the number of times partial reconstruction can be carried out is limited due to issues such as controlling the thickness of the furnace wall and hearth. However, by devising the shape of the iron cylinder components, it is possible to carry out partial reconstruction again, as described above, and in some cases, it can be carried out three or more times. The more times it is carried out, the greater the effect of reducing the amount of refractory waste. Furthermore, if partial reconstruction has been carried out once or multiple times and further partial reconstruction is no longer possible, the refractory is dismantled and removed, and a new furnace is constructed. [Example]

[0025] Examples of the present invention will be described below. The electric furnace used here was a 15-ton low-frequency induction furnace with an inner diameter of 1500 mm and a height of 3000 mm. Initially, the furnace wall refractory thickness was 120 mm and the hearth refractory thickness was 300 mm. The furnace power during operation was set to 2400 kW, and the iron source was melted. This operation was repeated 78 times, and when the furnace power dropped from 2400 kW to 3000 kW, the electric furnace was repaired using the partial furnace construction method according to the present invention. At this time, the furnace wall refractory thickness was 76.5 mm, and the hearth drop thickness was 257 mm. A steel cylinder with a height of 1500 mm and an inner diameter of 1120 mm was installed within the furnace body corresponding to the location of the worn portion, and a fluid repair refractory was poured and filled between the steel cylinder and the furnace wall. The next operation was performed in this state. The fluid repair refractory was SiO2 with a trace amount of B2O3 added. Several types of SiO2 were blended to ensure fluidity.

[0026] As a result, the repair refractories were sintered, and after repair the furnace wall refractories were 140 mm thick and the hearth bottom refractories were 257 mm thick, achieving partial furnace construction. The iron cylinder components were melted and became part of the molten steel. [Explanation of symbols]

[0027] 1. Electric furnace 10;furnace body 10a; Furnace wall 10b; hearth bottom 11;Ironhide 12; Refractories 15; wear and tear parts 16. Repair refractories 17. Sintered refractories 20: Iron cylinder parts

Claims

1. A repair method for an electric furnace for melting an iron source, in which, when a worn portion occurs in a refractory lining of a furnace body due to repeated operation, the worn portion is repaired, comprising: a step of filling the worn portion with a fluid repair refractory material; Next, a step of heating the furnace body with a heat source of the electric furnace to sinter the repair refractory; and A method for repairing an electric furnace, characterized in that the step of filling the repair refractory uses a blend of multiple types of silica-based refractories as the fluid repair refractory so as to ensure sufficient fluidity for filling the worn portion.

2. 2. The electric furnace repair method according to claim 1, wherein, when the worn portion includes a furnace wall, the step of filling the repair refractory includes setting an iron cylinder member so as to correspond to at least a portion of the inside of the furnace wall that includes the worn portion, and supplying the fluid repair refractory between the iron cylinder member and the portion that includes the worn portion.

3. The method further comprises, when a worn portion again occurs in the lining refractory due to repeated operation after the electric furnace has been repaired by sintering the repair refractory, a step of filling the worn portion again with the repair refractory having fluidity, and a step of sintering the repair refractory in the worn portion again, 2. The electric furnace repair method according to claim 1, wherein the step of filling the renewed worn portion with the repair refractory uses, as the fluid repair refractory, a blend of multiple types of silica-based refractories so as to ensure sufficient fluidity for filling the worn portion.

4. When the first worn portion and the second worn portion include a furnace wall, The step of filling the first-occurred worn portion with the repair refractory includes setting a first iron cylinder member so as to correspond to at least a portion of the inside of the furnace wall including the first-occurred worn portion, and supplying the flowable repair refractory between the first iron cylinder member and the portion including the first-occurred worn portion; 4. The electric furnace repair method according to claim 3, wherein the step of filling the repair refractory material into the renewed worn portion includes setting a second iron cylinder member so as to correspond to at least a portion of the inside of the furnace wall including the renewed worn portion, and supplying the fluid repair refractory material between the second iron cylinder member and the portion including the renewed worn portion.

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