converter

Abstract

To provide a converter furnace which is preferably used when used refractory products are sorted and recovered.SOLUTION: In a converter furnace, refractory products each having different qualities between its portions are installed and a boundary defining part is provided in each boundary part between the portions. It is preferable that the refractory products be placed in multiple tiers in a height direction and the portions be divided in the height direction by the boundary defining parts. Further, it is preferable that the boundary defining part be formed by one or two or more combinations selected from (1) a buffer material which absorbs expansion of the refractory product, (2) a different color part having a color different from that of the adjacent portion, and (3) the refractory product having a form different from that of the adjacent portion. Alternatively, it is preferable that a part of the refractory product include, in part of its material, a refractory scrap sorted and recovered for each quality.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a converter that is suitably used for separating and recovering refractories after use. [Background technology]

[0002] Converter refractories installed in converters are typically made of electrofused magnesia or high-purity graphite, often using high-quality raw materials. In particular, the workpiece refractories are generally graphite-containing, which minimizes slag infiltration and reduces degradation of the refractory quality after use, making them suitable for recycling. However, the load on the refractory varies depending on the location of the converter, such as the hearth, furnace wall, and slag line. Therefore, to achieve both economical efficiency and long life, converter refractories of different grades are often used depending on the load at the location. For example, in low-load areas, the purity of the electrofused magnesia or graphite raw materials may be changed, or cheaper sintered magnesia may be used instead of electrofused magnesia.

[0003] Therefore, the scraps of used refractories contain a mixture of refractories of various grades, and when they are recycled, they have no choice but to be used as low-grade raw materials. The grade of the refractories recovered is treated as the lowest grade refractory contained in the recovered materials.

[0004] Therefore, for example, Patent Document 1 considers a method for recycling used refractories. In addition, Patent Documents 2 and 3 propose methods for separating and recovering used refractories after dismantling, by marking the back of the refractory that remains even after use or painting the working surface before dismantling. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 05-339615 [Patent Document 2] Japanese Patent Application Publication No. 09-328377 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-212481 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional technology has the following problems. Converters use a huge amount of refractories, and a large amount of used refractories is generated at once. Therefore, even if the used refractories can be identified by symbols or other means, manually sorting through a large amount of used refractories is labor-intensive and also a significant burden in terms of cost. In the case of converters, compared to other vessels such as molten iron vessels, it is necessary to strictly select refractories of various grades depending on the part, making it particularly difficult to separate the refractories by grade.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a converter that can be suitably used when separating and recovering refractories after use. [Means for solving the problem]

[0008] The converter according to the present invention, which advantageously solves the above-mentioned problems, is a converter in which refractories of different grades are installed in different sections, and is characterized in that boundary partitions are provided at the boundaries between the sections.

[0009] The converter according to the present invention is (a) the refractories are arranged in a plurality of stages in the height direction, and the portions are divided in the height direction by boundary partitions; (b) the boundary partition is formed by one or a combination of two or more selected from (1) a buffer material that absorbs the expansion of the refractory material, (2) a different color portion that is different in color from the adjacent portion, and (3) a refractory material that has a different shape from the adjacent portion; (c) A portion of the refractories contains refractory waste separated and recovered according to grade as part of its raw materials; This is thought to be a more preferable solution. [Effects of the Invention]

[0010] According to the present invention, when converter refractories are dismantled, the refractories can be dismantled and collected by individual parts, allowing the refractories to be separated during dismantling. This eliminates the need for manual separation of dismantled debris and preliminary work such as marking refractories for identification. This not only reduces the burden of sorting work for recycling, but also enables recycling at low processing costs and by grade, resulting in economic benefits. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a vertical cross-sectional view showing a configuration of a converter according to one embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a partially enlarged perspective view of the vicinity of a boundary partition according to the embodiment. [Figure 3] (a) is a development view of brickwork using cushioning material in the boundary partition area in the above embodiment, (b) is a development view of brickwork using different colored areas in the same manner, and (c) is a development view of brickwork using profiled materials in the same manner. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail embodiments of the present invention. Note that the drawings are schematic and may differ from the actual embodiments. Furthermore, the following embodiments exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0013] (Configuration of converter) Fig. 1 is a schematic vertical cross-sectional view of a converter according to this embodiment. As shown in Fig. 1, this embodiment provides a converter in which refractories can be separated and recovered after use. Refractories (converter refractories) are installed in converter 1. Converter 1 is configured, in this order from the outer surface, with a steel shell 2, a permanent refractory layer 3, and a work refractory layer 4, and the refractories of the permanent refractory layer 3 and the refractories of the work refractory layer 4 are arranged in multiple stages in the height direction on the inner surface of converter 1.

[0014] The refractories in the converter 1 are constructed with refractories of various grades depending on the load on the refractory and the purpose of the refractory. In other words, the grade of the refractory constructed varies depending on the part of the converter 1. In this embodiment, the work refractory layer 4 is divided into various parts in the height direction of the converter 1, and the refractories of the work refractory layer 4 are divided (attached) in the height direction of the converter 1, i.e., by stage, so as to be classified by material, or at least grade for recycling. In the example of FIG. 1 , a low-grade refractory 41 is used as the refractory of the work refractory layer 4 near the uppermost furnace throat, where the thermal load is small. The slag line of the furnace wall has the highest thermal load, so a high-grade refractory 43 is used as the refractory of the work refractory layer 4, and a medium-grade refractory 42 is used as the refractory of the work refractory layer 4 for the remaining furnace wall and furnace bottom.

[0015] In this embodiment, as shown in the enlarged perspective view of the converter inner wall in FIG. 2 , boundary sections 5 are provided at the boundaries between the workpiece refractory layers 4, i.e., at the boundary sections between refractories 42 and 43 of different grades (i.e., at the boundary sections where refractories of different grades meet), to enhance the visibility of the boundaries during dismantling. As shown in FIG. 3( a), the boundary sections 5 are formed by buffer materials 51 provided between the refractory sections of different grades. The buffer materials 51 are made of, for example, cardboard or non-combustible mineral fibers that can absorb the expansion of the refractory (i.e., are compressed by the expansion of the refractory). It is preferable that the buffer materials 51 leave traces even after the converter is used, so that they can be seen during dismantling. In the example shown in FIG. 3( a), the buffer materials 51 are depicted higher than they actually are to emphasize the boundary sections 5; however, their actual height is approximately 2 mm.

[0016] 3(b), the refractory (brick) of the step at the material boundary may be colored to provide a different color portion 52 that is a different color from the other refractories (e.g., black), thereby forming the boundary partition 5. In this case, when installing the refractory, it is preferable to color at least the top surface of the refractory (other than the working surface A shown in FIG. 2) in advance with a paint such as a chrome-based paint that does not discolor due to heat and that can be seen against the black of the adjacent refractories. This makes it easier to see the boundary partition 5 when dismantling the refractory from above.

[0017] Alternatively, the refractory (brick) in the row corresponding to the boundary partition 5 may have a different shape from the adjacent refractory, such as a deformed material 53 with a different size (height) as shown in Figure 3(c). The boundary partition 5, which differs in shape from the adjacent refractory, can be, for example, an existing deformed portion (a portion where the brick shape changes), such as the boundary where the narrowing from the straight body section to the throat of the converter 1 begins or the angle change section connecting the hearth to the straight body. Furthermore, the above configurations may be combined, such as by coloring the deformed material 53 or the buffer material 51. Making the boundary partition 5 visible facilitates the classification of the refractory grade during dismantling. While Figures 3(b) and (c) show the bottommost row in the upper section as the boundary partition 5, the topmost row in the lower section may also be the boundary partition 5. It is preferable to use the bottommost row in the upper section as the boundary partition 5. If the topmost row in the lower section is used as the boundary partition 5, it is preferable to make the boundary between the materials visible on its top surface. This prevents refractories of different grades from being mixed in when dismantling them from above.

[0018] (Disassembly method) Next, a method for dismantling the refractory of the converter 1 and separating and recovering it will be described. First, when the refractory is installed, a boundary partition 5 is formed in advance at the material boundary portion of the work refractory layer 4. Then, when repairing and dismantling the converter 1, the converter 1 is rotated and fixed at the refractory dismantling position, and the refractory is dismantled into the converter 1, layer by layer, starting from the top. Once the refractory has been dismantled down to the boundary partition 5 (material boundary), the converter 1 is turned upside down, and the dismantled refractory is removed and recovered.

[0019] Thereafter, the converter 1 is again rotated and fixed to the refractory dismantling position, and the refractory below the boundary compartment 5 is dismantled row by row into the converter 1. When the refractory has been dismantled down to the next boundary compartment 5 (material boundary), the converter is again turned upside down and the dismantled refractory is removed and recovered. In this way, by managing the number of rows to be dismantled during converter dismantling and repeating the process of removing and recovering the refractory each time the number of rows to be dismantled reaches the range in which refractory of the same quality has been installed, it becomes possible to easily recover refractory by grade without prolonging the construction period.

[0020] In the above embodiment, the boundary between materials is made visible by providing the boundary partition 5. Instead of or in addition to the boundary partition 5, in order to identify the layers in which the same-grade refractories exist during dismantling, it is also possible to count the number of layers from the top or bottom when dismantling a converter, or to grasp the dismantling height using a laser rangefinder or the like.

[0021] (recycled refractories) The separated and collected refractory waste is crushed and magnetically separated according to its grade, and then pulverized to a particle size suitable for use as raw material. The resulting recycled refractory raw material can be used in part to produce magnesia-carbon bricks as recycled refractories, for example, by a high-density brick manufacturing method using a low-viscosity binder. The recycled refractories can then be reused as refractories of a specified grade for use in converters after their properties have been evaluated in advance. [Example]

[0022] As shown in Figure 1, refractories of different grades were lined in an actual converter, and attempts were made to separate, dismantle, and recover the materials. Commercially available magnesia-carbon bricks were used for the refractories of different grades. Low-grade refractories 41 made of 97% pure electrofused magnesia were placed from the converter furnace throat, which had the lowest load, to above the straight body. Medium-grade refractories 42 made of 98% pure electrofused magnesia were placed from the top of the straight body to above the slag line, which comes into contact with the molten slag, and throughout the entire area below the slag line. Furthermore, high-grade refractories 43 made of the highest quality 98.5% pure electrofused magnesia were placed in the slag line, which comes into contact with the molten slag and has the highest load. In addition, cardboard was concentrated in the rows corresponding to the boundaries between these grades as boundary partitions 5, and these were used in actual operation.

[0023] Due to wear and tear of the refractory, it was dismantled in order to reload the converter refractory. Prior to the dismantling, the slag, metal, and other materials attached to the furnace body were removed, the furnace mouth metal fittings were removed, and after removing these items that had been dropped under the furnace, the dismantling of the refractory began.

[0024] To dismantle the refractory, a converter dismantling machine equipped with an air breaker powered by compressed air was used. The converter was placed on its side, and dismantling began when the surface temperature of the converter refractory dropped below 500°C.

[0025] Dismantling began from the topmost layer of converter refractories, and the refractory material that corresponded to the converter ceiling, which was laid on its side, was dismantled into the converter up to the same layer as the tap hole, which was the construction range of low-grade refractory 41. After that, the furnace body was turned upside down, and the refractory material up to the dismantled layer was dropped below the furnace. The dropped refractory material was removed from under the furnace using a wireless heavy machine, transported to a temporary storage location, and managed as low-grade refractory scrap.

[0026] The converter was again turned on its side, and the tap hole refractory was further dismantled. Then, the medium-grade refractory 42 up to the top of the slag line was dismantled in the same manner, dropped under the furnace, and transported to a temporary storage area like the low-grade refractory 41, and then managed as medium-grade refractory scrap.

[0027] Similarly, only the slag line portion, which was high-grade refractory 43, was dismantled and managed as high-grade refractory scrap.

[0028] After the refractories in the slag line section were dismantled, dropped and recovered, all that remained was medium-grade refractories 42, which were then dismantled down to the bottom of the furnace, dropped under the furnace and managed together with the medium-grade refractory scraps that had been recovered earlier.

[0029] The refractory waste, which was managed by grade, was crushed, magnetically separated, and then pulverized to the raw material particle size to produce recycled refractory raw materials. Magnesia carbon bricks (refractories) were prototyped and evaluated using a high-density brick manufacturing method that blended 30% of the resulting recycled refractory raw materials and used a low-viscosity binder. Test Nos. 3 to 5 are shown in Table 1.

[0030] As a comparative example, a refractory (Test No. 2) was produced using refractory scrap obtained by a conventional dismantling method without dismantling by grade (conventional scrap) as a recycled refractory raw material. Furthermore, as reference examples, a high-grade refractory (Test No. 1) was produced using the highest quality electrofused magnesia with a purity of 98.5%, which is a raw material for high-grade refractories, without using recycled raw materials; a commercially available low-grade refractory (Test No. 6) using electrofused magnesia with a purity of 97%; and a commercially available medium-grade refractory (Test No. 7) using electrofused magnesia with a purity of 98% were also prepared and evaluated.

[0031] To evaluate corrosion resistance, rotating drum corrosion tests were conducted 10 times at 1700°C on slag adjusted to a basicity of C / S = 3, and the corrosion resistance index was compared, with the wear amount in test No. 1 set at 100. The lower the corrosion resistance index, the higher the corrosion resistance. Basicity C / S is the ratio of CaO to SiO2 in the slag on a mass basis. The results of this series of experiments are shown in Table 1.

[0032] [Table 1]

[0033] Comparing Test No. 1 with Test Nos. 3 to 5, it can be seen that the corrosion resistance index increases when recycled raw materials are added, but the extent of this increase, i.e., the degree of deterioration in corrosion resistance, varies depending on the quality of the recycled raw materials; the higher the quality of the recycled raw materials, the lower the degree of deterioration.

[0034] The maximum corrosion resistance index values ​​for Test No. 2 and Test No. 3 were almost the same, indicating that the presence of low-grade scrap determines the maximum corrosion resistance index value. Furthermore, among Test Nos. 3 to 5, the range of corrosion resistance index values ​​was widest for Test No. 3, where low-grade refractory scrap was used. This is thought to be because medium-grade refractory was installed around the tap hole, and was mixed in and recovered during demolition. Since the medium-grade and high-grade refractory scrap were not mixed with refractories of other grades, the corrosion resistance index values ​​showed little variation and were of stable quality.

[0035] In all of Tests Nos. 3 to 5, the corrosion resistance index was lower than that of the low-grade refractory used as a reference example (Test No. 6), indicating that there is no problem with using recycled material blended bricks, at least in the low-grade refractory construction range. Tests Nos. 4 and 5 had slightly higher corrosion resistance indexes than the medium-grade refractory (Test No. 7), but roughly the same corrosion resistance index was obtained, indicating that recycled material blended bricks using medium-grade refractory waste and high-grade refractory waste can be applied to the medium-grade refractory construction range.

[0036] The above describes an embodiment of the invention made by the inventors, but the present invention is not limited by the description that forms part of the disclosure of the present invention according to the present embodiment. Furthermore, while the refractories have been described here as being divided into three grades, low, medium, and high, the same effect can be obtained even if the number of grade classifications is increased or decreased. Therefore, all other embodiments, examples, and operational techniques made by those skilled in the art based on the present embodiment are all included in the scope of the present invention. [Industrial Applicability]

[0037] The converter of the present invention not only reduces the burden of dismantling, but also allows the refractories to be separated and recovered according to grade, allowing them to be recycled and used as converter refractories, thereby providing economic benefits and being industrially useful.Furthermore, the invention can be applied to facilities and equipment that separate and install refractories of different grades. [Explanation of symbols]

[0038] 1 Converter 2 Ironhide 3 Permanent refractory layer 4. Work refractory layer 41 Low-grade refractories 42 Medium grade refractories 43 High-grade refractories 5 Boundary division 51 Cushioning material 52 Unusual Section 53 Deformed material A Working surface

Claims

1. A converter in which refractories of different grades are installed in different parts, A boundary partition is provided at the boundary between the sections, The boundary partition is formed by one or a combination of two or more selected from (1) a buffer material that absorbs expansion of the refractory material, (2) a different color portion that is different in color from adjacent portions, and (3) a refractory material that has a different shape from adjacent portions.

2. 2. The converter according to claim 1, wherein the refractories are arranged in a plurality of stages in the height direction, and the portions are divided in the height direction by boundary partitions.

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