JP7485910B2 - Refractory construction method - Google Patents

Description

The present invention relates to a method for constructing refractory materials to be lined inside a refining vessel.

The refining vessel is lined with refractory that can withstand high temperatures. The remaining dimensions of the lining refractory decrease with repeated use due to melting damage to the slag and cracks caused by thermal shock. Refractory that falls below a certain remaining dimension or has deteriorated due to cracks is dismantled and reconstructed to ensure stable operation of the refining vessel. The refractory lining is composed of multiple layers with the main purpose of preventing molten metal leakage, and includes permanent refractory and wear refractory from the steel shell side. Bricks and castables are used as refractories, with bricks having a denser structure and better corrosion resistance than castables, while castables are characterized by the fact that they can be easily constructed by pouring. Refractory construction using bricks is carried out manually, but it is quite heavy work because it involves transporting heavy objects, and construction takes a long time. In addition, brick construction requires advanced skills such as dealing with deformation of the steel shell, so it is necessary to have a furnace builder with construction skills perform the work. However, in recent years, it has become difficult to secure enough furnace builders due to harsh working conditions and a declining labor force.

In response to the above-mentioned problems, the following methods have been proposed to mechanize and reduce the labor required for refractory construction. Patent Document 1 proposes a method for making castable refractory linings and a construction device for the same. By making castable refractory linings, it is possible to mechanize and reduce the labor required for construction work to a certain extent, and castable refractory linings are being used for areas with little wear, such as the linings of molten steel ladles and tundishes. However, castable refractories do not provide sufficient durability in facilities where refining processes are severe, such as converters, so bricks, which have higher durability than castable refractories, are still used today. Patent Document 1 also relates to a construction method for making worn refractories castable, and does not mention permanent refractories.

Patent Documents 2 and 3 propose a method for mechanizing the construction of wear bricks for refining vessels. Although there is a description of stacking bricks in accordance with the inclination of the refining vessel and mechanizing the construction to accommodate vessels with different inside diameters, there is a problem that the construction of wear bricks cannot be carried out accurately if the steel shell of the vessel is deformed. In addition, there is no description of a method for constructing permanent refractories. When constructing by hand, it is possible to deal with deformation of the steel shell by processing the bricks or using joint mortar, but as mentioned above, there are various problems with constructing by hand.

Japanese Utility Model Application Publication No. 58-9273 Patent No. 2627891 Japanese Patent Application Laid-Open No. 62-178884

The present invention was made in consideration of the above problems, and aims to provide a method for constructing refractory linings for refining vessels that can shorten construction time and reduce labor.

The present invention relates to the following configuration.
[1] A method for constructing a refractory material including wear bricks and permacastables to be used to line a smelting vessel, the method comprising the steps of: constructing the wear bricks using a device for holding and constructing the wear bricks, based on the working surface of the constructed wear bricks; and pouring permacastables into the gap between the back surface of the constructed wear bricks and the steel shell.
[2] A method for constructing a refractory material according to [1], comprising the steps of: constructing at least one layer of wear bricks; pouring permacastable refractory onto the back surface of the constructed wear bricks; and constructing a further wear brick on top of the constructed wear bricks.
[3] A method for constructing a refractory material according to [1], which alternates between a step of constructing a wear brick to a height of 2000 mm or less based on the installed height of the perm castable refractory and a step of pouring the perm castable refractory onto the back surface of the constructed wear brick.
[4] A method for constructing a refractory material according to any one of [1] to [3], in which permanent bricks are arranged on the inside of the steel shell, and permanent castable refractories are poured between the back surface of the constructed wear bricks and the working surface of the permanent bricks.

According to the present invention, by constructing wear bricks based on the working surface and making the back permanent castable, the bricks can be placed in the designated position without being affected by the deformation of the steel shell, and the construction of wear bricks can be mechanized while maintaining construction accuracy. This shortens the construction time compared to constructing them by hand, and also realizes labor savings.

FIG. 2 is a diagram illustrating a process for constructing a refining vessel according to one embodiment of the present invention. FIG. 1 is a diagram showing the relationship between the free flow value and filling property of permacastable refractory at each construction height. FIG. 2 is a diagram showing the lining structure of a molten metal ladle in an embodiment.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

1 is a diagram showing a schematic diagram of a construction process of a refining vessel according to one embodiment of the present invention. In this embodiment, a refining vessel 1 in which a refractory material including a permanent brick 3, a permanent castable 4, and a wear brick 5 is lined on a steel shell 2 is mechanically constructed using a robot arm 6 and a castable pouring device 7. In the illustrated example, the robot arm 6 and the castable pouring device 7 are placed on a liftable stand 8 and positioned at an appropriate height position in the refining vessel 1. The robot arm 6 constructs one layer of wear bricks 5 by arranging the wear bricks 5 in a predetermined shape formed by the working surface after construction, specifically, for example, a circle based on the center of the vessel. When the wear bricks 5 are constructed based on the working surface in this way, the influence of deformation of the steel shell 2 is not taken into consideration, but as described later, the permanent castable 4 is poured on the back side of the wear bricks 5, so that no gaps are generated in the refractory lining structure. The perimeter of the wear bricks 5 arranged in the above manner remains constant regardless of deformation of the steel shell 2, so the wear bricks 5 only need to have one shape, and the required number can be specified in advance.

After the robot arm 6 has built one or more layers of wear bricks 5, the castable casting device 7 is used to cast the permanent castable 4 into the gap between the steel shell 2 and the back surface of the wear bricks 5, thereby forming a permanent lining. In the illustrated example, the permanent bricks 3 are arranged inside the steel shell 2, so the permanent castable 4 is cast into the gap between the working surface of the permanent bricks 3 and the back surface of the wear bricks 5. If at least one layer of wear bricks 5 has been built, the permanent castable 4 can be cast without a formwork. After one or more layers of wear bricks 5 have been built, the casting of the permanent castable 4 and the construction of the upper layer of wear bricks 5 may be carried out in parallel. Alternatively, the casting of the permanent castable 4 and the construction of the upper layer of wear bricks 5 may be carried out alternately.

Since the thickness of the permanent lining is thin, if the height of the refining vessel 1, for example about 4,500 mm, is poured in at once, the filling capacity of the castables is insufficient and a satisfactory finished product cannot be obtained. As shown in Figure 2, if pouring is performed into a gap of 50 mm thickness, which is the general thickness of permanent lining, as the construction height increases, poor filling of the finished product occurs even if the flow value (free flow) of the castables is increased.

Therefore, in the first example of the present invention, after at least one layer of wear bricks 5 is constructed, the process of pouring and constructing the permanent castable 4 is carried out in parallel with the process of constructing the wear bricks 5. Since the height of one layer of wear brick wall is, for example, about 230 mm, as shown in the graph in Figure 2, a construction body with good filling properties can be obtained even with castables with low moisture and low flow values, and improved durability can also be expected.

The wear bricks 5 constructed before the pouring of the permanent castable 4 do not necessarily have to be one tier. For example, it is possible to increase the flow value of the castable within the durability limit, construct two or more tiers of wear bricks 5, and then pour and construct the permanent castable 4 in parallel.

In a second example of the present invention, after at least one layer of wear bricks 5 has been built, a process of building one or more additional layers of wear bricks 5 and a process of pouring permanent castable 4 are alternately performed. For example, when the working areas of the robot arm 6 and the castable pouring device 7 interfere with each other, it is appropriate to alternate the processes as in this example. As a third example, depending on the positioning of the robot arm 6 and the castable pouring device 7 at the time, the processes may be performed in parallel if the devices do not interfere with each other, and may be alternated while the devices interfere with each other.

In the case of alternately carrying out the steps in the second example above, the time required for construction will be longer than in the case of parallel carrying out of the steps as in the first example. In order to shorten the time required for construction, two or more tiers of wear bricks 5 may be constructed and the permanent castable 4 may be poured in all at once behind them. When the pouring construction limit of normal permanent castable 4 was examined, it was found that, for example, by adjusting the moisture content, etc., the flow value is raised to 200 mm, the upper limit at which durability can be maintained, as shown in Figure 2, the upper limit construction height at which filling can be ensured is 2000 mm, and the number of tiers of wear bricks 5 to be constructed all at once can be set within this range.

According to one embodiment of the present invention as described above, the time required for construction is reduced compared to conventional manual construction. The construction time for the wear brick 5 using the robot arm 6 is calculated using formula (1).

In the first example of the present invention described above, the construction of the wear bricks 5 and the pouring of the permanent castable 4 are carried out in parallel, so the total construction time of the refractory lining is approximately equal to the time calculated by formula (1).

On the other hand, in the second example of the present invention described above, the construction of the wear bricks 5 and the pouring of the permanent castable refractory 4 are performed alternately, so the total construction time of the lining refractory is the time calculated by formula (1) plus the pouring time of the permanent castable 4 calculated by formula (2).

From the above formula (2), the pouring construction time of the permanent castable 4 can be shortened by pouring the permanent castable 4 into the backs of two or more layers of wear bricks 5 in one go, thereby reducing the number of pours and reducing the preparation time required for each pour. For example, the pouring preparation time can be reduced by eight times (2000/230 = 8.7) when pouring is performed every brick layer (230 mm) compared to when pouring is performed all at once at the above-mentioned maximum construction height (2000 mm).

Below, we will explain the results of applying the present invention to a molten iron ladle as an example of the present invention. The test conditions and results of the example are shown in Table 1.

The refractory of the molten iron ladle in each embodiment was originally a three-layer structure consisting of two layers of 30 mm thick permanent bricks (perm bricks 3A and 3B) and one layer of 180 mm thick wear bricks 5 from the steel shell 2 side, as shown in Fig. 3. The wear bricks 5 had 19 stages, each stage being 230 mm high, and the total construction height was 4,370 mm. The present invention was applied in accordance with the timing of repairs to this molten iron ladle. During dismantling, only the permanent bricks (perm bricks 3A) on the steel shell side were left, and the permanent bricks (perm bricks 3B) on the working surface side were changed to permanent castable refractory 4, so that the refractory structure was the same as that of the example shown in Fig. 1. The brick construction of the underlayment was also carried out as usual, and the present invention was applied to the construction of the wear bricks 5 and permanent castable refractory 4 on the side walls. The permanent castable 4 was made of Al ₂ O ₃ -SiO ₂ castable (Al ₂ O ₃ : 65%, SiO ₂ : 30%). The robot arm 6 was made of YASKAWA Electric YR-MPL0100-J00, and was installed based on the center of the molten iron ladle. Bricks of a single shape were loaded on a pallet and brought into the ladle beside the device using a crane, and the wear bricks 5 were constructed by picking them up one by one with the robot arm 6 and arranging them in order based on the designed working surface position of the wear bricks. Although the steel shell 2 was deformed by repeated thermal loads, the gap between the working surface side of the permanent brick 3 and the back side of the wear brick 5 was 35 mm to 45 mm, which was larger than the designed thickness of the permanent castable construction of 30 mm, and there was no extremely narrow gap in any part, so there was no problem with the construction of the permanent castable 4. The corrosion resistance of the permanent bricks and castables was evaluated by a rotational erosion test. Samples cut from the permanent bricks and the permanent castables after construction were fired at 300°C for 12 hours, lined inside a cylinder with a horizontal rotation axis, heated with an oxygen-propane burner, and slag was added to corrode the refractory surface. The test temperature and time were 1500°C for 5 hours, the slag composition was CaO/ _SiO2 = 1, FeO = 15%, and the slag was repeatedly discharged and added every 30 minutes. The corrosion resistance index in the table is the remaining thickness after the rotation corrosion test, indexed with the thickness of the permanent bricks (Comparative Examples 1 and 2 described below) set at 100, and the higher the value, the higher the durability.

In Example 1, after one layer of wear bricks was constructed, pouring of the permanent castable was started, and construction of the wear bricks was continued in parallel. Calculating the construction time from the above formulas (1) and (2), the construction time of the wear bricks using the robot arm was 2280 (pieces)/100 (pieces/h) = 22.8 (h), and since the permanent castable was poured one layer later, it took 0.1 ( ^m3 )/1.5 ( ^m3 /h) = 0.07 (h). In addition, the drying time to sufficiently evaporate the moisture of the permanent castable to prevent problems such as explosion took 25 hours longer than in the conventional method, but by using multiple drying devices and carrying out the drying process and construction process in parallel, the extended drying time did not affect the construction period.

Perma Castable 4 uses materials with an appropriate added moisture content in the range of 5% to 7%. Normally, 7% moisture is added to increase the flow value, but in this test, pouring was carried out with the lowest added moisture content of 5% (flow value 145), and construction was completed without any problems. In Example 1, each layer of brick was poured in parallel, so there were no filling defects and a good construction was obtained. Furthermore, construction with a low moisture content of 5% resulted in a dense structure and was able to maintain the same corrosion resistance as permanent bricks. With castables, there is no concern about molten metal leaking from gaps in the joints as with brick construction, so the present invention is also advantageous from the perspective of preventing molten metal leaks.

In Example 2, after three tiers of wear bricks were constructed, the robot arm was stopped and the permanent castable was poured in. After the three tiers of permanent castable were poured, the robot arm was used again to construct three tiers of wear bricks (4th to 6th tiers), and then the robot arm was stopped and the permanent castable was poured in. This alternating operation of constructing wear bricks and pouring permanent castable was repeated seven times to construct 19 tiers of wear bricks and permanent castable. The material and added moisture of the permanent castable were the same as in Example 1. The height of the three tiers of wear bricks was 690 mm, and a good construction was obtained without any filling defects using castable with added moisture of 5%. Calculating the construction time from the above formulas (1) and (2), the construction time for the wear bricks using the robot arm was 22.8 (h), the same as in Example 1, and the pouring time for the permanent castable was (0.3 ( ^m3 )/1.5 (m3/ ^h ) + 1 (h)) x 7 = 8.4 (h). As in Example 1, the drying time took 25 hours longer than before, but this had no effect on the construction period. In addition, the structure of the resulting construction body was densified by reducing the added moisture, and it was possible to maintain the same corrosion resistance as permanent bricks.

In Example 3, after eight tiers of wear bricks were constructed, the robot arm was stopped and the permanent castable was poured. After the eight tiers of permanent castable were poured, the robot arm was used again to construct eight tiers of wear bricks (9th to 16th tiers), and then the robot arm was stopped and the permanent castable was poured. Finally, the robot arm was used to construct eight tiers of wear bricks (17th to 19th tiers), and then the permanent castable was poured to complete the construction. The material of the permanent castable was the same as in Example 1, and the added moisture was 7% (flow value 195). The height of the eight tiers of wear bricks was 1840 mm, and a good construction was obtained without any filling defects using castable with an added moisture of 7%. Calculating the construction time from the above formulas (1) and (2), the construction time for the wear bricks using the robot arm was 22.8 (h), similar to Example 1, and the pouring time for the perm castable was (0.8 ( ^m3 )/1.5 (m3 ^/h ) + 1 ( ^h )) x 2 + (0.3 ( ^m3 )/1.5 (m3/h) + 1 (h)) = 4.3 (h). As in Example 1, the drying time took 25 hours longer than in the conventional method, but there was no impact on the construction period. In this example, the perm castable was not made low-moisture, but the moisture content was within the appropriate range for added moisture, and there were no problems such as poor filling, so it was fully usable.

The test conditions and results for the comparative examples for the above examples are shown in Table 2.

In Comparative Example 1, the construction was carried out by conventional manual labor. The construction was carried out by five workers, and the permanent refractory was left as a two-layer brick structure as shown in Figure 3, and the wear bricks were placed by pressing their backs against the working surface of the permanent bricks. In other words, the wear bricks were constructed based on their backs, not their working surfaces. All the layers of permanent bricks were constructed before the wear bricks were constructed. For the wear bricks, one worker constructed 11 pieces per hour, and it took 40 hours to construct approximately 2,200 wear bricks. In addition to this, it took 24 hours to construct one layer of permanent bricks, which corresponds to the permanent castables in the Example. Since the construction can be carried out while processing the bricks in accordance with the deformation of the steel shell, no gaps (triangular joints) were formed on the backs or joints of the wear bricks, and the joint thickness was 2 mm or less, resulting in a good finish. However, the construction time was more than twice as long as that of the Example, and many workers were required.

In Comparative Example 2, as in Comparative Example 1, the permanent refractory material had a two-layer brick structure, and only the wear bricks were constructed using a robot arm. As in Comparative Example 1, the wear bricks were placed by pressing them against the permanent bricks on the back side, so even using the robot arm, construction took time (100 bricks/h could be placed per unit time based on the working surface, but 30 bricks/h based on the back side), and it took 75 hours to construct the wear bricks. In addition, because the wear bricks were not processed to match the deformation of the steel shell as in the case of manual construction, gaps (triangular joints) were formed on the back side and in the joints of the wear bricks, resulting in a poor finish.

In Comparative Example 3, as in Examples 2 and 3 above, a process of constructing wear bricks using a robot arm based on the working surface position and a process of pouring permanent castable were alternately carried out. However, the number of stages in which wear bricks were constructed was increased to nine, one more than in Example 3. In this case, the construction time for wear bricks was 22.8 (h), the same as in the Example, and the pouring time for permanent castable was 4.3 (h). However, by increasing the number of construction stages to nine, the construction height was increased to 2070 mm, and poor filling occurred even when the amount of water added to the castable was increased to the maximum of 7% and the fluidity was increased to the limit of 200 with a free flow value.

From the above-described examples and comparative examples, it can be seen that the construction time can be significantly reduced by constructing the wear bricks using a robot arm in the present invention. Here, in order to obtain the effect of shortening the construction time using the robot arm, it is preferable to construct the wear bricks based on the working surface of the wear bricks after construction, rather than on the back surface. In order to enable the construction of such wear bricks, at least the part of the permanent refractory that contacts the wear bricks is made of permanent castable, and is poured in parallel with the construction of the wear bricks, or alternately with the process of constructing an appropriate number of layers of wear bricks. The number of layers of wear bricks when constructed alternately with the pouring of permanent castable is appropriately set according to the characteristics of the permanent castable, but by constructing the wear bricks to a height of 2000 mm or less based on the constructed height of the permanent castable, the packing property of the permanent castable can be ensured and the corrosion resistance equivalent to that of the permanent bricks can be maintained.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to such examples. It is clear that a person with ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

1...refining vessel, 2...iron shell, 3...perm brick, 4...perm castable, 5...wear brick, 6...robot arm, 7...castable pouring device.

Claims (3)

1. A method for constructing a refractory material including ware bricks and permacastables for lining a smelting vessel, comprising the steps of:
building the wear brick with a wear brick gripping and building device relative to a working face of the wear brick after building;
and pouring the permacastable refractory into a gap between the back surface of the constructed wear brick and the steel shell .
The step of pouring the permanent castable is a step of constructing at least one layer of the wear bricks, and then pouring the permanent castable onto the back surface of the constructed wear bricks,
The method for constructing a refractory material includes the steps of: (a) forming a wear brick on top of the previously constructed wear brick; 1. A method for constructing a refractory material including ware bricks and permacastables for lining a smelting vessel, comprising the steps of:
building the wear brick with a wear brick gripping and building device relative to a working face of the wear brick after building;
and pouring the permacastable refractory into a gap between the back surface of the constructed wear brick and the steel shell .
The step of constructing the wear brick is a step of constructing the wear brick to a height of 2000 mm or less based on the construction height of the permacastable refractory,
and pouring said permanent castable against the back surface of said constructed wear brick . A permanent brick is disposed inside the steel shell,
3. The method for constructing a refractory material according to claim 1 or 2 , wherein the perma castable is poured between the back surface of the constructed wear brick and the working surface of the perma brick.

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