JP5907312B2 - Method for manufacturing lining structure of molten metal container - Google Patents

Description

  The present invention relates to a method for manufacturing a lining structure of a molten metal container and a lining structure of a molten metal container.

  The lining structure of various molten metal containers such as torpedo car, blast furnace, steelmaking converter, molten steel ladle is the outermost outer shell of the molten metal container. steel shell) is provided, which is composed of a permanent refractory and a lining refractory in order toward the inside of the molten metal container. The working face (of refractory) of the innermost lined refractory is in contact with the molten metal. As the characteristics of the lining refractory in the molten metal container, corrosion resistance against slag, which is a molten metal or a coexisting molten oxide, and resistance to spalling due to temperature change are required.

  In general, a refractory lining containing alumina and magnesia undergoes spinelization by sintering after construction. The volume of the refractory expands as the spinelization progresses, and the voids present in the refractory decrease. Accordingly, the refractory can be densified to reduce the porosity, and the slag can be prevented from entering the refractory, so that the wear rate of the refractory can be reduced.

  In the process of using the molten metal container, a sudden rise or fall in temperature occurs near the working surface of the lining refractory. Therefore, as described above, when the method of spineling alumina and magnesia after applying the lining refractory is applied to a molten metal container, the following problems occur. In other words, if spinelization near the working surface of the lining refractory is not sufficiently advanced, the temperature rises due to heat received from the molten metal in the process of use, causing thermal expansion of the lining refractory, but this thermal expansion and spinelization There is a problem that cracks occur in the lining refractory material due to the structural expansion associated therewith.

  On the other hand, in Patent Document 1, alumina and magnesia that are not spineled are used as main materials as the refractory for the lining, and after the refractory for the lining is applied, firing is performed at a high temperature of 1300 ° C. or more for 4 hours or more. By doing so, it is disclosed to spinel the refractory for lining before using the molten metal container.

  Patent Document 2 proposes that a small amount of silica (silica) that lowers the melting point is added to rapidly advance spinelization.

Japanese Patent Laid-Open No. 10-167846 Japanese Patent No. 4220131

  However, in the method disclosed in Patent Document 1, before using the molten metal container, the working surface of the lining refractory is heated to 1300 ° C. or more for 4 hours or more using a burner, so that the refractory lining is made spinel. However, in order to heat the working surface of the lining refractory at 1300 ° C. or higher, a powerful burner facility is required. Also, inside the refractory lining, the temperature drops from the working surface toward the permanent refractory, that is, toward the back of the refractory. In order to make it spinel, enormous energy is required. Therefore, it is not economical to apply the method disclosed in the cited document 1.

  In Patent Document 2, a small amount of silica that lowers the melting point is added, and a liquid phase is partially generated, whereby rapid spinelization is achieved with respect to normal solid phase diffusion. However, the decrease in fire resistance due to the addition of silica impairs the advantage of spinelization that densifies the refractory and prevents the intrusion of slag. When preheated for a long time without adding silica There is a problem that fire resistance is inferior compared to.

  The present invention has been made for such a problem, and does not require a strong burner facility as in the prior art, and a method for producing a molten metal container lining structure having sufficient fire resistance and melting An object of the present invention is to provide a lining structure for a metal container.

The present invention has been made with respect to the above problems, and has the following characteristics.
[1] A method for manufacturing a lining structure of a molten metal container having a steel skin on the outside, a refractory lining on the inside, and a permanent refractory between the iron skin and the lining refractory,
Between the iron skin and the permanent refractory, a heat insulating material having a heat transfer coefficient of 100 W / m ² K or less is provided.
Non-fired refractory containing 60% by mass or more of alumina and 4% by mass or more of magnesia as the lining refractory and having a linear change rate at room temperature of 0.8% or more before and after heat treatment at 1500 ° C. for 3 hours. Constructing unfired refractory and / or unshaped refractory,
The manufacturing method of the lining structure of a molten metal container which preheats the working surface of the said lining refractory before using the said molten metal container.
[2] The lining refractory before construction contains 50% by mass or more of the magnesia as periclase or calcined dolomite,
In the preheating before use of the molten metal container, the molten metal container according to [1], wherein in the lining refractory before construction, a part of magnesia that is periclase or calcined dolomite is preheated until it is spineled with alumina. Method for manufacturing the lining structure of the present invention.
[3] A molten metal container lining structure manufactured by the method for manufacturing a molten metal container lining structure according to [1] or [2].

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the lining structure of the molten metal container which has sufficient fireproof performance, and the lining structure of a molten metal container which do not require the strong burner installation like the past can be provided. .

FIG. 1 is a view showing a lining structure of a molten metal container according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the distance from the working surface of the lining refractory according to Invention Example 1 (with heat insulation) and Comparative Example 3 (without heat insulation) and the spinelization ratio of magnesia.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  First, the outline of the present invention will be described. In the production of the lining structure of the molten metal container, the present invention uses a material that can spinel alumina and magnesia as the lining refractory after the lining refractory construction, while providing a heat insulating layer between the iron skin and the permanent refractory. It was discovered that by installing it, the refractory cost could be greatly reduced without deteriorating the equipment cost and energy cost, and it was completed.

  In other words, more than half the amount of magnesia is blended as periclase or calcined dolomite, and the refractory is densified by spinelization. In order to reduce the cracks caused by the combined expansion with the expansion accompanying the progress of spinelization, a heat insulating layer is provided on the iron skin side of the lining refractory. Thereby, the temperature gradient inside the lining refractory is moderately increased, and the temperature of the back surface of the lining refractory and the temperature up to the back surface is increased. As a result, the ratio of spinel formation during preheating after construction is increased, and spinelization is further advanced to a sufficiently deep portion, so that the expansion associated with the progress of spinelization after the start of actual use, that is, after the operation of the lining refractory starts It is possible to reduce cracks and suppress cracks. Thereby, the refractory cost can be greatly reduced without deteriorating the equipment cost and the energy cost. In addition, the back surface of the lining refractory refers to a surface opposite to the working surface, that is, the surface in contact with the molten metal.

  FIG. 1 is a view showing an example of a lining structure of a molten metal container according to an embodiment of the present invention. An iron skin 1 is provided on the outermost side of the molten metal container. The lining structure is in contact with molten metal (not shown) on the inner side, that is, on the right side of the drawing. The lining structure includes a heat insulating material 2, a permanent refractory material 3, and a lining refractory material 4 in order from the iron skin 1 to the inside, that is, in the direction in which molten metal enters (lining direction).

In the above lining structure in which the heat insulating material 2 is provided between the permanent refractory 3 and the iron skin 1, the heat insulating material 2 has a heat transfer coefficient of 100 W / m ² K or less. Generally, the heat transfer coefficient of the permanent refractory 3 is about 100 W / m ² K. Here, the heat transfer coefficient is a value obtained by dividing the thermal conductivity of each refractory layer such as the lining refractory 4, the permanent refractory 3, and the heat insulating material 2 by the thickness of each layer.

By configuring the heat insulating material 2 as a heat insulating material having a heat transfer coefficient of 100 W / m ² K or less, which is lower than that of the permanent refractory 3, the temperature gradient inside the lining refractory 4 is gradually reduced, In addition, the temperature up to the back surface can be increased, and spinelization of the lining refractory 4 can be sufficiently advanced by preheating before use. Since the heat insulating material 2 is generally porous and has low fire resistance, the heat insulating material 2 is provided between the iron shell 1 and the permanent refractory 3 in order to keep the temperature of the heat insulating material 2 low.

Here, the thermal conductivity of an inexpensive heat insulating material is about 0.3 W / mK. If such a heat insulating material is applied as the heat insulating material 2 and the construction thickness is 3 mm, the heat transfer coefficient is 100 W / m ² K. For example, the construction thickness is doubled to 6 mm, the heat transfer coefficient is lowered to 50 W / m ² K, or the heat conductivity is about 0.03 W / mK, although it is somewhat expensive, If the heat transfer coefficient can be lowered to 10 W / m ² K, the effect of the present invention is further increased.

The permanent refractory 3 is usually made of brick such as alumina and has a joint filled with mortar. The heat transfer coefficient of the permanent refractory 3 is about 100 W / m ² K. Although illustrated as one layer in FIG. 1, two layers of the permanent refractory 3 may be provided.

  The lining refractory 4 is an unfired refractory and / or an amorphous refractory in which alumina and magnesia are spineled by sintering after application of the refractory, including alumina and magnesia. The “non-fired refractory” refers to a refractory that is not fired in advance after molding and before construction, and the “indefinite refractory” refers to a refractory that is not previously molded before construction. The lining refractory 4 is preferably composed of one or both of an unfired refractory and an amorphous refractory containing 60% by mass or more of alumina and 4% by mass or more of magnesia. More preferably, it is preferable that the lining refractory 4 contains 80% by mass or more of alumina and 5% by mass or more of magnesia except when graphite or the like is blended for a special application.

Moreover, in the lining refractory 4 before spinelizing alumina and magnesia, 50 mass% or more of magnesia is included in the refractory as periclase or baked dolomite. Thereby, since the ratio which turns into a spinel after construction can be made high, the effect which densifies the lining refractory 4 and improves corrosion resistance is acquired. Here, depending on the market conditions of the raw material price, it is more preferable that 90% by mass or more of magnesia is supplied as periclase.
The unfired refractory and / or the amorphous refractory constituting the lining refractory 4 has a linear change rate at room temperature before and after heat treatment at 1500 ° C. for 3 hours (hereinafter, line change after heat treatment at 1500 ° C. The rate is also adjusted to 0.8% or more. By setting the linear change rate after heat treatment at 1500 ° C. to 0.8% or more, in the case of the lining structure including the heat insulating material 2 described above, after use as a molten metal container during preheating after refractory construction ( After operation), the effect of improving the corrosion resistance by densifying the lining refractory 4 by spineling of alumina and magnesia is obtained. Here, the heat treatment temperature is set to 1500 ° C. and the heat treatment time is set to 3 hours, considering the temperature history on the working surface side of the lining refractory 4 after use (after operation) as a molten metal container, and a lining by spinel formation. This is because it is used as an index of densification of the refractory 4.
In addition, when the linear change rate at room temperature after heat treatment at 1500 ° C. is less than 0.8%, the effect of improving the corrosion resistance by densifying the lining refractory 4 even when the lining structure including the heat insulating material 2 is used. Is not enough. On the other hand, in the lining structure that does not include the layer of the heat insulating material 2, if the linear change rate at room temperature after heat treatment at 1500 ° C. is 0.8% or more, the ratio of spineling at low temperature during preheating after construction is low. Therefore, since the expansion due to the spinel progresses rapidly in the initial stage of use (operation) of the lining refractory 4, the synthesis of the thermal expansion at the time of a rapid temperature rise after the use of the lining refractory 4 and the expansion due to the spinel Cracking occurs due to expansion, and there is a possibility that the effect of extending the life of the refractory can not be fully enjoyed by improving the corrosion resistance by densifying the refractory by spinel formation.
Furthermore, it is more desirable that the linear change rate at room temperature after heat treatment at 1500 ° C. is 1.5% or more in order to improve the corrosion resistance by densifying the lining refractory 4. Here, the linear change rate after heat treatment at 1500 ° C. is a method in which the positive value corresponds to expansion and the negative value corresponds to contraction, respectively, and the content of magnesia in the refractory to be contained in the refractory as periclase or baked dolomite is increased. And can be adjusted to decrease by a method such as increasing the content of titania, iron oxide, and silica contained in the refractory as impurities.

  In addition, as a refractory to be used for the refractory 4 of the molten metal lining, a material containing 60% by mass of alumina and 4% by mass or more of magnesia can sufficiently exhibit the effect of improving corrosion resistance by spinelization. Can do.

  In the lining structure as described above, when the heat insulating material 2 is interposed between the iron skin 1 and the permanent refractory 3, the effect of promoting the spinelization of the lining refractory 4 is a molten metal. Appears in the drying / preheating process of the lining refractory 4 before use of the container.

Conventionally, when the lining refractory 4 is dried and preheated, if the temperature of the working surface of the lining refractory 4 is not maintained at 1300 ° C. or more and for four hours or more, the refractory 4 of the lining refractory 4 will not be spineled. It was. In contrast, in the present invention, the temperature of the working surface of the lining refractory 4 can be raised to 800 ° C. by providing the heat insulating material 2 having a heat transfer coefficient of 100 W / m ² K or less on the back side of the lining refractory 4. In this case, spinelization of the lining refractory 4 in the vicinity of the working surface can be sufficiently advanced. From the viewpoint of shortening the drying / preheating time, the surface (working surface) temperature of the lining refractory at the end of the drying / preheating process is more preferably 900 to 1200 ° C.

  Therefore, the crack resulting from the rapid temperature rise by the heat receiving from the molten metal after the start of use of a molten metal container can be suppressed more effectively. In addition, this makes it possible to significantly reduce the refractory cost without deteriorating the equipment cost and energy cost. In addition, since it is not necessary to add silica as in the prior art, fire resistance is maintained.

  Next, examples of the present invention will be described. The effect of the present invention was investigated using the lining structure shown in FIG. Table 1 shows the conventional examples, Comparative Examples 1 to 5 and Invention Example 1 that were investigated. In Inventive Example 1, all the components including magnesia other than periclase are unfired refractories and / or amorphous refractories.

(Conventional example) In a lining structure, the inner refractory 4 is 91 mass% alumina-6 mass% magnesia, and 5/6 of magnesia (mass basis) is preliminarily blended as alumina-magnesia spinel at 1500 ° C. A cast amorphous refractory material having a linear change rate of 0.1% at room temperature after the heat treatment was used. In the conventional example, the heat insulating sheet 2 was not constructed. The heat transfer coefficient of the permanent refractory 3 is 100 W / m ² K. The lifetime was 225 heat.

(Comparative Example 1) In the lining structure shown in FIG. 1, as the lining refractory 4, 91 mass% alumina-6 mass% magnesia same as the conventional example, and 5/6 of magnesia (mass basis) is alumina- A cast amorphous refractory material blended as magnesia spinel and having a linear change rate of 0.1% at room temperature after heat treatment at 1500 ° C. was used. A heat insulating sheet 2 having a thermal conductivity of 0.2 W / mK and a thickness of 3 mm was applied between the iron skin 1 and the permanent refractory 3. The total heat transfer coefficient of the heat insulating sheet 2 and the permanent refractory 3 is 40 W / m ² K. As a result, the life was 20% worse than the conventional example.

  After collecting and investigating the refractory after use, the infiltration depth of calcium oxide or silica, which is a slag component, into the refractory is as deep as 40 mm compared to the usual 30 mm, and cracks at the boundary Was also recognized. In general, it is said that when heat insulation is performed on the back side of the refractory, the temperature of the refractory increases and the durability deteriorates, and the same result was obtained with an alumina-magnesia material.

  (Comparative Example 2) Next, as the lining refractory 4, heat treatment at 1500 ° C., in which 91 mass% alumina-6 mass% magnesia and 4/6 of magnesia (mass basis) were previously blended as alumina-magnesia spinel. A cast amorphous refractory made of a material having a line change rate of 0.3% was used. Insulation similar to that of Comparative Example 1 was performed. As a result, although the infiltration depth was reduced to about 30 mm, the life of the lining refractory 4 was about the same as or slightly worse than that of the conventional example.

(Comparative example 3) Further, as the lining refractory 4, the linear change rate after heat treatment at 1500 ° C, in which 91 mass% alumina-6 mass% magnesia and 95 mass% or more of magnesia were blended as periclase, was 1.5. % Flow-in amorphous refractories were used. In Comparative Example 3, no heat insulating sheet was applied. As a result, the life of the lining refractory 4 is about 11% longer than that of the conventional example.
(Comparative Example 4) As the lining refractory material 4, a non-cast refractory material having a flow rate of 94 mass% alumina-3 mass% magnesia and 95 mass% or more of magnesia blended as periclase was used. An insulation sheet was constructed. As a result, the life of the lining refractory 4 was longer than that of the conventional example but shorter than that of Comparative Example 3. This is because even when magnesia with a high periclase ratio is used, if the total amount of magnesia is less than 4% by mass, the linear change rate at room temperature after heat treatment at 1500 ° C. is as low as 0.7%, and the effect of densifying the refractory is sufficient. It was thought that this was not possible.
(Comparative Example 5) As the lining refractory 4, an alumina raw material with a little impurities is used, 90 mass% alumina-6 mass% magnesia, 95 mass% or more of magnesia is blended as periclase, and impurities coming from the alumina raw material (titania) A heat-insulating sheet similar to that of Comparative Example 1 was constructed using a cast amorphous refractory material having a linear change rate of 0.7% after heat treatment at 1500 ° C., which is 1 mass% of iron oxide, silica). As a result, the life of the lining refractory 4 was longer than that of the conventional example but shorter than that of Comparative Example 3. This is because even when magnesia with a high periclase ratio is used, the linear change rate at room temperature after heat treatment at 1500 ° C. is as low as 0.7% due to the influence of impurities that tend to generate a liquid phase with a low melting point, and the refractory is densified. It was thought that this effect was not sufficiently obtained.
In addition, in the lining refractories 4 used in other comparative examples, conventional examples, and invention examples 1, impurities (titania, iron oxide, silica) coming from the alumina raw material were 0.5% by mass and are shown in Table 1. In any of the test examples, the balance other than the sum of the numerical values shown as the composition is components such as impurities other than alumina and magnesia coming from the magnesia raw material and the alumina cement.

  (Invention Example 1) As lining refractory 4, 91 mass% alumina-6 mass% magnesia same as Comparative Example 3, and 95 mass% or more of magnesia was blended as periclase at room temperature after heat treatment at 1500 ° C. A material having a linear change rate of 1.5% was used. Moreover, the heat insulation sheet similar to the comparative example 1 was constructed. As a result, the life of the lining refractory 4 was 33% longer than that of the conventional example.

  That is, the life extension by changing the material of the lining refractory 4 is 11%, which is the extension of the life of the comparative example 3, and in addition to this, the life extension by providing a layer of the heat insulating material 2 is an example of the present invention. This is considered to be 22%, which is the difference in the extension of the lifetime between 1 and Comparative Example 3.

  In the lining structures in Invention Example 1 and Comparative Example 3, at the end of preheating before use, the temperature of the working surface of the lining refractory 4 was 1200 ° C., and the spinelization ratio of the lining refractory 4 after preheating for 48 hours was As shown in FIG. FIG. 2 is a diagram showing the relationship between the distance from the working surface of the lining refractory and the magnesia spinelization ratio in Invention Example 1 (with heat insulating material) and Comparative Example 3 (without heat insulating material). The thickness of the lining refractory 4 is 130 mm.

  In Comparative Example 3 that does not have the heat insulating material 2, in the present invention example 1 that has the heat insulating material 2, the spinelization ratio is 24 to 30 points higher in each part, especially in the central portion having a depth of 56 to 75 mm. The ratio was 35% with respect to 11%, and the ratio of spinelization was 3.2 times that of Comparative Example 3.

As a result, 60 mass% or more of alumina and 4 mass% or more of magnesia are contained, and 50 mass% or more of magnesia is the lining refractory 4 supplied as periglace, and the iron skin 1 and the permanent refractory 3 It was found that the lifetime of the lining refractory 4 can be extended by providing a heat insulating material having a heat transfer coefficient of 100 W / m ² K or less during

  Of course, the present invention is not limited to the above-described embodiments, and various design changes can be applied.

DESCRIPTION OF SYMBOLS 1 Iron skin 2 Heat insulation material 3 Permanent tension refractory 4 Lined refractory

Claims (3)

A method for producing a lining structure of a molten metal container having a permanent refractory and a lining refractory in order from the iron skin side,
Between the iron skin and the permanent refractory, a heat insulating material having a heat transfer coefficient of 100 W / m ² K or less is provided.
Non-fired refractory containing 60% by mass or more of alumina and 4% by mass or more of magnesia as the lining refractory and having a linear change rate at room temperature of 0.8% or more before and after heat treatment at 1500 ° C. for 3 hours. Construction and / or irregular refractories,
The manufacturing method of the lining structure of a molten metal container which preheats the working surface of the said lining refractory at the temperature of 800 degreeC or more and less than 1300 degreeC before using the said molten metal container.   It is a manufacturing method of the lining structure of the molten metal container of Claim 1, Comprising: Before using the said molten metal container, preheating the working surface of the said lining refractory at the temperature of 800 degreeC or more and 1200 degrees C or less. A method for manufacturing a lining structure of a molten metal container, characterized in that The lining refractory before construction includes 50% by mass or more of the magnesia periclase or baked dolomite,
3. The melting according to claim 1, wherein in the preheating before use of the molten metal container, in the lining refractory before construction, a part of magnesia that was periclase or calcined dolomite is preheated until it is spineled with alumina. A manufacturing method of a lining structure of a metal container.

Images