Method for Separating and Recycling Refractory Materials

Abstract

To provide a technology which sorts and recovers used refractory products in a converter furnace more easily.SOLUTION: In a sorting recovery method of refractory products, used refractory products each having different qualities between its portions are sorted and recovered in a converter furnace in which the refractory products are installed, and a step in which the used refractory products are disassembled into the portions and recovered is repeated. In the converter furnace, the refractory products are placed in multiple tiers in a height direction and the portions are divided in the height direction. In the step, it is preferable to disassemble and recover the refractory products for each step having the same quality, provide a boundary defining part in each boundary portion between the portions, and form the boundary defining part by a buffer material which absorbs expansion of the refractory product, a different color part whose color is different from that of the adjacent portion, or the refractory product having a form different from that of the adjacent portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for separately collecting refractory materials that separately collect refractory materials after the use of a converter.

Background Art

[0002] For the converter refractories installed in a converter, fused magnesia and high-purity graphite are used, and many of the raw materials used are of high grade. In particular, the working refractories are generally graphite-containing refractories, with little slag infiltration and little quality degradation of the used refractories due to slag, so they are suitable for recycling. However, the loads on the refractories vary depending on the parts of the converter such as the furnace bottom, furnace wall, and slag line. Therefore, in order to achieve both economic efficiency and service life, converter refractories are often made of different grades according to the load at the installation location. For example, in low-load parts, the purity of fused magnesia or graphite raw materials may be changed, or inexpensive sintered magnesia may be used instead of fused magnesia.

[0003] Therefore, the disintegrated scraps of the used refractories contain refractories of various grades, and when recycling, they have to be used as low-grade raw materials. The grade of the recovered refractories is treated as the lowest-grade refractory contained in the recovered materials.

[0004] Therefore, for example, in Patent Document 1, a recycling method for used refractories is being studied. Also, in Patent Documents 2 and 3, methods for separately collecting used refractories after disintegration have been proposed, such as marking the back of the refractory that remains even after use or painting the working surface with a color before disintegration.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] However, the prior art has the following problems. In a converter, a very large amount of refractories are used, and a large amount of used refractories are generated at one time. Therefore, even if the used refractories can be identified by symbols or the like, manually sorting a large amount of used refractories is heavy labor and also a large burden in terms of cost. In the case of a converter, compared with other containers such as a hot metal container, it is necessary to strictly use different grades of refractories according to the parts, so it is particularly difficult to separate the refractories by grade.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for more easily separating and recovering used refractories of a converter. MEANS FOR SOLVING THE PROBLEMS

[0008] The method for separating and recovering refractories according to the present invention, which advantageously solves the above problems, is a method for separating and recovering used refractories in a converter in which refractories of different grades are installed for each part, characterized in that the step of disassembling and recovering the used refractories for each part is repeated.

[0009] In addition, the method for separating and recovering refractories according to the present invention is (a) In the converter, the refractories are arranged in a plurality of stages in the height direction and the parts are divided in the height direction, and in the step, the refractories are disassembled and recovered for each stage of the same grade, (b) A boundary section is provided at the boundary between the parts, (c) The boundary section is formed by a buffer material that absorbs the expansion of the refractories, (d) The boundary section is formed by a different-color section having a different color from the adjacent part (e) The boundary section is formed by refractory materials having different forms with respect to adjacent parts. The above are considered to be more preferable solutions. [Advantages of the Invention]

[0010] According to the present invention, when disassembling the converter refractory, the refractory can be disassembled and recovered for each part, so that the disassembly can be performed while separating the refractory. Therefore, prior operations such as manual separation work of the disassembled scraps and symbol application to the refractory for identification are unnecessary, which not only reduces the load of the sorting work for recycling, but also enables recycling at a low processing cost and by grade, so that economic effects can be enjoyed. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

[0012] Hereinafter, embodiments of the present invention will be specifically described. Note that each drawing is schematic and may be different from the actual one. Further, the following embodiments illustrate devices and methods for embodying the technical idea of the present invention, and do not specify the configuration to the following. That is, various changes can be made to the technical idea of the present invention within the technical scope described in the claims.

[0013] (Configuration of Converter) Figure 1 is a schematic longitudinal sectional view of a converter suitable for use in the method for separating and recovering refractories according to the present embodiment. As shown in Figure 1, in the present embodiment, the refractory (converter refractory) is installed in the converter 1. The converter 1 is composed of an iron skin 2, a permanent refractory layer 3, and a working refractory layer 4 in this order from the outer surface, and the refractories of the permanent refractory layer 3 and the working refractory layer 4 are arranged in a plurality of stages in the height direction on the inner surface of the converter 1.

[0014] For each refractory in the converter 1, refractories of various grades are installed according to the load on the refractory and the purpose of the refractory. That is, the grades of the refractories installed for each part of the converter 1 are different. In the present embodiment, the working refractory layer 4 is divided into parts in the height direction of the converter 1, and the refractories of the working refractory layer 4 are divided (laid separately) for each stage in the height direction of the converter 1, that is, according to the grade at least when recycled. In the example of Figure 1, since the heat load is small in the vicinity of the uppermost furnace mouth, low-grade refractory 41 is used as the refractory of the working refractory layer 4. Since the slag line in the furnace wall has the maximum heat load, high-grade refractory 43 is used as the refractory of the working refractory layer 4, and medium-grade refractory 42 is used as the refractory of the working refractory layer 4 for the remaining furnace wall and furnace bottom.

[0015] In the present embodiment, as shown in the enlarged perspective view of the inner wall part of the converter in Figure 2, at the boundary part between each part of the working refractory layer 4, that is, at the dividing part of the refractories 42 and 43 with different grades (the boundary stage where the refractories with different grades are in contact), a boundary partitioning part 5 is provided to enhance the visibility of the boundary part during disassembly. The boundary partitioning part 5 is formed, for example, by a buffer material 51 provided between the stages of the refractories with different grades as shown in Figure 3(a). This buffer material 51 is composed of, for example, cardboard or incombustible mineral fiber that can absorb the expansion of the refractory (compressed by the expansion of the refractory). It is preferable that the buffer material 51 leaves a trace even after the use of the converter and can be visually recognized during disassembly. In the example shown in Figure 3(a), in order to emphasize the boundary partitioning part 5, the height of the buffer material 51 is drawn higher than the actual height, but the actual height of the buffer material 51 is about 2 mm.

[0016] Also, as shown in Fig. 3(b), a boundary section 5 may be formed by coloring the refractory bricks at the step of the material boundary portion to provide a different-color portion 52 having a color different from that of other refractory bricks (for example, black). In this case, during the construction of the refractory bricks, it is preferable to pre-color at least the upper surface (other than the operating surface A shown in Fig. 2) of the refractory bricks with a paint that does not change color due to heat, such as a chromium-based paint, and that is visible against the black color of the adjacent refractory bricks. This facilitates visual recognition of the boundary section 5 when disassembling the refractory bricks from above.

[0017] In addition, the refractory bricks at the step corresponding to the boundary section 5 may be in a different form from the adjacent refractory bricks, for example, a deformed member 53 having a different size (height) as shown in Fig. 3(c). As the boundary section 5 having a different form from the adjacent refractory bricks, for example, an existing deformed portion (a portion where the shape of the refractory brick changes), such as the boundary where the constriction from the straight body portion of the converter 1 to the furnace mouth starts or the angle change portion connecting the furnace bottom to the straight body, can be used as the boundary section 5. Also, the above configurations may be combined, such as making the deformed member 53 a different color or coloring the buffer member 51. By making the boundary section 5 visible, it becomes easier to separate the grades of the refractory bricks during disassembly. In Figs. 3(b) and (c), the lowermost step of the upper portion is used as the boundary section 5, but the uppermost step of the lower portion may also be used as the boundary section 5. It is preferable to use the lowermost step of the upper portion as the boundary section 5. When using the uppermost step of the lower portion as the boundary section 5, it is preferable to make the material boundary visible on its upper surface. This can prevent the mixing of refractory bricks with different grades when disassembling the refractory bricks from above.

[0018] (Disassembly method) Next, a method for disassembling and separately recovering the refractory bricks of the converter 1 will be described. First, during the construction of the refractory bricks, a boundary section 5 is pre-formed at the material boundary portion of the working refractory brick layer 4. Then, during the repair and disassembly of the converter 1, the converter 1 is rotated and fixed at the refractory brick disassembly position, and the refractory bricks are disassembled into the converter 1 step by step from the upper stage in order. When disassembling up to the boundary section 5 (material boundary), the converter 1 is turned upside down, and the disassembled refractory bricks are carried out and recovered.

[0019] After that, the converter 1 is rotated and fixed again at the refractory dismantling position, and the refractories below the boundary section 5 are dismantled into the converter 1 step by step. When the dismantling reaches the next boundary section 5 (material boundary), the converter is turned upside down again, and the dismantled refractories are carried out and recovered. In this way, by managing the number of steps to be dismantled during converter dismantling and repeating the process of carrying out and recovering the refractories each time the dismantling reaches the number of steps in the range where the same-grade refractories are installed, it becomes possible to simply recover the refractories by grade without prolonging the construction period.

[0020] In the above embodiment, the boundary section 5 is provided so that the material boundary can be visually recognized. Instead of or in addition to the boundary section 5, a configuration may be adopted in which the number of steps is counted from the upper or lower part during converter dismantling or the dismantling height is grasped by a laser distance meter or the like so that the steps where the same-grade refractories exist can be known during dismantling.

Example

[0021] As shown in FIG. 1, different-grade refractories were pasted on an actual converter, and separate dismantling and recovery were attempted. Commercially available magnesia carbon bricks were used as the refractories with different grades. From the converter mouth with the lowest load to above the straight body part, low-grade refractories 41 using 97% grade fused magnesia were arranged. From the upper part of the straight body part to above the slag line part in contact with the slag and the entire lower part of the slag line part, medium-grade refractories 42 using 98% grade fused magnesia were arranged. Further, high-grade refractories 43 using 98.5% grade top-grade fused magnesia were arranged at the slag line part in contact with the slag, which has the highest load. In addition, cardboard was intensively arranged as the boundary section 5 at the steps corresponding to these grade boundaries and used in actual operation.

[0022] Due to refractory wear, the refractories were dismantled for relining the converter refractories. Prior to dismantling, after removing the furnace body deposits such as slag and scrap metal, the furnace mouth fittings were removed and dropped under the furnace, and after removing these, the dismantling of the refractories was started.

[0023] For the demolition of the refractory, a converter demolition machine equipped with an air breaker powered by compressed air was used. With the converter laid on its side, demolition began when the surface temperature of the converter refractory dropped below 500°C.

[0024] Demolition started from the uppermost part of the converter refractory. After demolishing the refractory at the part hitting the ceiling of the horizontally laid converter up to the same level as the tapping hole, which is the construction range of the low-grade refractory 41, into the converter, the furnace body was rotated upside down, and the refractory up to the demolished level was dropped to the bottom of the furnace. The dropped refractory was moved from under the furnace by a wireless crane and then transported to a temporary storage location and managed as low-grade refractory scraps.

[0025] With the converter laid on its side again, after further demolishing the tapping hole refractory, the medium-grade refractory 42 up to the slag line part was continuously demolished in the same way, then dropped to the bottom of the furnace, transported to the temporary storage location in the same way as the low-grade refractory 41, and managed as medium-grade refractory scraps.

[0026] Similarly, only the slag line part, which is the high-grade refractory 43, was demolished and managed as high-grade refractory scraps.

[0027] After demolishing, dropping, and recovering the refractory at the slag line part, since all the rest was the medium-grade refractory 42, it was demolished down to the bottom of the furnace, dropped to the bottom of the furnace, and managed together with the previously recovered medium-grade refractory scraps.

[0028] The refractory scraps managed by grade were each crushed, subjected to magnetic separation, and then pulverized to the raw material particle size to obtain recycled refractory raw materials. 30% of the obtained recycled refractory raw materials was blended, and magnesia carbon bricks (refractories) were trial-produced and evaluated by a high-density brick manufacturing method using a low-viscosity binder. It is shown in Table 1 for Test Nos. 3 - 5.

[0029] As a comparative example, a refractory (Test No. 2) was trial-produced and evaluated, which used refractory scraps (conventional scraps) obtained by a conventional dismantling method without dismantling by grade as recycled refractory raw materials in the same way. Also, as reference examples, a high-grade refractory (Test No. 1) trial-produced using the highest-grade electrofused magnesia of 98.5% purity, which is the raw material of high-grade refractory, without using recycled raw materials, a commercially available low-grade refractory (Test No. 6) using electrofused magnesia of 97% purity, and a commercially available medium-grade refractory (Test No. 7) using electrofused magnesia of 98% purity were prepared and evaluated.

[0030] For the evaluation of corrosion resistance, a rotary drum erosion test was conducted 10 times at 1700 °C on slag adjusted to have a basicity C / S = 3, and the results were compared using a corrosion resistance index with the loss of Test No. 1 set as 100. Note that the lower the numerical value of the corrosion resistance index, the higher the corrosion resistance. The basicity C / S is the ratio of CaO to SiO2 in the slag on a mass basis. The results of a series of experiments are shown in Table 1.

[0031]

Table 1

[0032] Comparing Test No. 1 with Test Nos. 3 - 5, it can be seen that the corrosion resistance index increases with the blending of recycled raw materials, but the increase range, that is, the degree of deterioration of corrosion resistance, varies depending on the grade of the recycled raw materials. The higher the grade of the recycled raw materials, the lower the degree of deterioration.

[0033] In Test No. 2 and Test No. 3, the maximum value of the corrosion resistance index is almost the same, indicating that the maximum value of the corrosion resistance index is determined by the presence of low-grade scraps. Also, in Test Nos. 3 - 5, the range of the corrosion resistance index is the widest when using low-grade refractory scraps in Test No. 3. This is considered to be because medium-grade refractories are constructed around the tapping hole and are mixed and recovered during dismantling. Medium-grade refractory scraps and high-grade refractory scraps do not have other grades of refractories mixed in, so the variation in the corrosion resistance index is small and the quality is stable.

[0034] In all of Tests No. 3 to 5, the corrosion resistance index is lower than that of the low-grade refractory used as a reference example (Test No. 6), indicating that at least the use of recycled raw material bricks in the low-grade refractory construction range is problem-free. In Tests No. 4 and 5, the corrosion resistance index slightly increases compared to that of the medium-grade refractory (Test No. 7), but corrosion resistance indexes of approximately the same level are obtained, indicating that recycled raw material bricks using medium-grade refractory scraps and high-grade refractory scraps can be applied to the medium-grade refractory construction range.

[0035] As described above, the embodiments to which the invention made by the present inventors is applied have been described. However, the present invention is not limited by the description that forms part of the disclosure of the present invention according to this embodiment. Also, although the refractory has been described by dividing it into three grades: low grade, medium grade, and high grade this time, the same effects can be obtained by increasing or decreasing the number of grade classifications from this. Therefore, all those other than those listed in the above examples are included in the scope of the present invention. Furthermore, all other embodiments, examples, and operation techniques made by those skilled in the art based on this embodiment are included in the scope of the present invention.

Industrial Applicability

[0036] According to the method for separately collecting refractories of the present invention, in addition to reducing the disassembly load, refractories can be separately collected by grade, so they can be recycled and used for converter refractories, and economic benefits can be enjoyed, making it industrially useful. Also, it can be applied to facilities and devices for constructing different grades of refractories separately.

Explanation of Signs

[0037] 1 Converter 2 Iron skin 3 Permanent refractory layer 4 Working refractory layer 41 Low-grade refractory 42 Medium-grade refractory 43 High-grade refractory 5 Boundary section 51 Buffer material 52 Different color part 53 Irregular-shaped material A Operating surface

Claims

Claim 1 A method for separately recovering refractory materials, which are used in a converter in which refractories with different qualities are constructed for each part, and after use, the refractory materials are separately recovered. When repeating the step of disassembling and recovering the used refractory materials for each part, A method for separately recovering refractory materials, characterized in that a boundary section is provided at a boundary portion between the parts. Claim 2 In the converter, the refractory materials are arranged in a plurality of stages in the height direction, and the parts are divided in the height direction. In the step, the refractory materials are disassembled and recovered for each stage with the same quality. The method for separately recovering refractory materials according to Claim 1. Claim 3 The method for separately recovering refractory materials according to Claim 1 or 2, wherein the boundary section is formed by a buffer material that absorbs expansion of the refractory material. Claim 4 The method for separately recovering refractory materials according to Claim 1 or 2, wherein the boundary section is formed by a different-color portion having a different color from an adjacent part. Claim 5 The method for separately recovering refractory materials according to Claim 1 or 2, wherein the boundary section is formed by refractory materials having different forms from an adjacent part.

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