JPS59225878A - Refractory lining method of vessel for molten metal - Google Patents

Abstract

PURPOSE:To minimize the erosion of refractories and to improve the life of the refractories by joining refractories of different materials by providing a downward angle relative with the normal of the working surface of the refractories to the boundary surface of said refractories. CONSTITUTION:The boundary surface 7a of refractories of different materials is provided with a prescribed downward angle theta relative with the normal 12 of the working surface 5a of the refractories. More specifically, if the angle theta decreases, the effect of decreasing the damage in the joint part of the boundary is low and if the angle theta is too large, a problem arises in terms of production and installation of the refractories. The damage in the joint part 7 at the boundary in the casing of subjecting the upper and lower parts of a vessel for molten metal to zone lining with refractories of different materials such as a basic material and an acidic material, etc. is thus minimized and the life of the refractories is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refractory lining method for minimizing erosion of refractories in molten metal containers and extending the life of the refractories.

The most severe damage to the refractory lining of molten metal containers such as molten steel pots occurs on the walls of the slag line zone, where slag remains at high temperatures for long periods of time. Therefore, so-called zone lining is generally performed in which the molten metal bath zone wall and the slag line zone wall are lined with refractories made of materials having different corrosion resistance depending on the damage rate.

To give an example of zone lining under conventional operating conditions, the molten metal bath zone wall is lined with waxite (Si0275~
85% by weight, A220325-15% by weight) refractories,
Zircon quality (Z? 0240~) on the slag line zone wall
60% by weight, 5i0260 to 40% by weight) was sufficiently handled by using a refractory, and since both were similar acidic materials, almost no reaction occurred between the materials.

However, due to continuous casting or ladle refining associated with higher quality steel, the receiving temperature of the molten metal container is -h J'
? , L. At present, when the residence time has been extended, the lifespan of the L refractories is too short, causing problems in terms of both cost and operation. Therefore, the molten metal bath zone was made of acidic zircon refractory material, and the slag line zone wall was made of basic material.
For example, lining with magnesia carbon (Mg 085-80% by weight, 015-20% by weight 41%) refractory is no longer necessary. Since these refractories are made of completely different materials, boundary damage occurs at the boundary joint, with the maximum value occurring at the boundary joint 7, as shown in FIG. Such boundary damage to the refractory defeats the purpose of achieving the intended goal of zone lining with optimum erosion balance.

The present invention provides a method for minimizing damage at the boundary joint 7 when the lower part of a molten metal container is zone-lined with refractories of different materials such as basic material and acidic material.
- This is a lining method aimed at extending the life of refractories.

In order to elucidate the boundary damage mechanism that occurs between refractories made of different materials, the inventor first placed Mg085~ in an aluminum crucible 8 in a high frequency induction furnace 11 as shown in Fig. 80% magnesia carbon brick 5
A laboratory study was conducted in which various neutral to acidic bricks 6a containing various types of 5i02 were placed at the bottom, and the molten m2 was heated with an induction coil 9 and held at 1600'C for 2 hours. The results are shown in FIGS. 3 and 4. FIG. 3 shows a cross section near the boundary joint 7+1 between the upper magnesia carbon brick 5 and the lower bricks 6a, and 13 is the damaged area of the boundary between 1-the lower brick. Figure 4 shows the lower brick 6
Elution 5i02 amount of a, that is (lower brick elution loss amount)
It is a graph illustrating the relationship between (S i 02 content %) on the horizontal axis and the boundary damage area on the vertical axis. In other words, it was found that -1 damage to the lower end joint portion 7 of some of the magnesia carbon bricks 5 was greatly influenced by the amount of eluted silica (Si-02) from the material of the lower brick 6a. In other words, it can be said that damage at a boundary joint between refractories made of different materials is determined by the type and amount of eluate rising from below. - As a measure to prevent damage to the boundary joints described in (11), it is recommended to place refractories made of materials that are least likely to cause boundary reactions at the bottom. This results in poor balance and increased costs.

The present invention aims to align the interface between the upper and lower refractories in the molten metal container to the normal to the operating surface of the refractories in order to balance the overall erosion loss of the refractories in the molten metal container and minimize boundary damage. By forming the refractory at a downward angle, reaction between the eluate sealed in from the F side and the refractory material above is made less likely to occur. That is, the gist of the present invention is -1: In the refractory lining of a molten metal container in which the wall of the slag line zone and the wall of the lower molten metal bath zone are constructed with refractories of different materials, A refractory lining method for a molten metal container is characterized in that the boundary surfaces of objects are joined at a downward angle with respect to the normal to the operating surface of the refractory.

FIG. 5 illustrates a cross-sectional view of a lining constructed according to the present invention.

The reason why the boundary 11 of the lining constructed according to the present invention has a long service life is considered as follows.

First, the melt and gas of large N particles in molten steel are
J-H according to Kusu's principle. As shown in Fig. 6, the joint angle is (a) when the boundary surface 7a coincides with the normal line 12 of the refractory working surface 5a; (b) when the boundary surface 7a coincides with the normal line 12 of the refractory working surface 5a; (C) When the boundary surface 7a has a downward angle θ with respect to the normal 12 of the refractory operating surface 5a. Even if the loss progresses in the same way in all three cases, cavities due to the rising flow 14 are more likely to occur in (a) and (b) than in (C),
The reaction area between this rising melt and gas (acidic substance) and the refractory material (basic substance) in the upper slag line zone is wide, and the reaction time is also long. Furthermore, (a), (b)
In the case of (C), the boundary joint 7 has a natural shape that is easily damaged by the ``-M melt and gas horizontally or in the ``- direction, whereas in the case of (C), the refractory melt is rising. And the shape prevents damage to the base of the boundary 11 in the do direction due to gas. Therefore, in the case of (C), 1 sun (a), (
Boundary W damage is less likely to progress than in b).

In addition, in the case of (C), the angle of the operating surface 5a with respect to the downward angle 0 with respect to the line 12 is 11 (1-), which is most effective at 15° to 75°.

In other words, as the angle θ becomes smaller, the aforementioned effect of reducing boundary joint damage becomes weaker, and if the angle 0 becomes too large,
This is because problems arise in the production of refractories, Group 1-1.

At the boundary between upper and lower dissimilar refractories, refractories of different materials are bonded together in advance to produce an integral refractory with the interface between the refractories of different materials inclined with respect to the normal to the operating surface of the refractories. Then, when a refractory lining is constructed using this, it is preferable from the viewpoint of refractory stacking construction, and has the effect of further extending the life of the refractory.

Figure 7 shows the slag line life (number of heats) of a molten steel ladle in which the molten metal bath zone wall is lined with zircon refractory and the slag line zone wall is lined with magnesia carbon refractory.
It is a graph showing the relationship with the molten steel desulfurization treatment ratio. In Fig. 7, O indicates the downward angle that the interface between refractories of different materials makes with respect to the normal to the operating surface of the refractories, θ = 0° is an example of construction using the conventional method, and θ - 45° is an example of construction using the conventional method. This is an example constructed by the method of the present invention.

In FIG. 7, the molten steel desulfurization treatment ratio is the ratio of the molten steel desulfurization treatment heat to the total received steel heat.

Molten steel desulfurization treatment is a process of removing S from the steel by charging and blowing desulfurization flux into the molten steel ladle after receiving the steel, and vigorously stirring the molten steel. That is, the molten steel ladle refractories are exposed to severe conditions such as higher temperatures, stronger stirring, and the effects of input flux, resulting in significant wear and tear.

From FIG. 7, the excellent effects of the present invention are clear.

In other words, when the molten steel desulfurization treatment ratio is 20%, the slag line life was 50 heats at θ = 0°, but when θ = 4
By setting it at 5°, its lifespan is towards 80 heats.
1-Shit. As a result of this, the total cost will be reduced due to the extension of the life of refractories, reduction in construction costs, reduction in drying costs, etc.
If the cost of the conventional method is 100, the cost of the method of the present invention is 54, resulting in a cost reduction of 46%.

[Brief explanation of the drawing]

Figure 1 is a partial cross-sectional view of a molten metal container showing an example of boundary damage between refractories made of different materials, Figure 2 is a cross-sectional view of a high-frequency induction furnace test equipment, Figure 3 is a partial cross-sectional view, and Figure 4 is a partial cross-sectional view of the high-frequency induction furnace test equipment. 5i0
Figure 5 is a cross-sectional view of the lining constructed by the method of the present invention; Figure 6 is a partial cross-sectional view of refractories with various interfaces; Figure 7 is a graph showing the relationship between molten steel desulfurization treatment ratio and slag line life. l... Slag 2... Molten steel 3... Steel skin 4... Permanently tensioned refractory 5... Slag line zone refractory 5a... Refractory operating surface 6... Molten metal bath zone refractory Object 6a...Various test bricks 7...Boundary part 7a...Boundary surface 8...Aluminum crucible 9...Induction coil 10...Erosion line of used refractory 11.・High frequency induction furnace 12 ・Normal to the working surface of the refractory 13 ・Boundary damage area 14 ・1−Rising wave α ・Upward angle O of the boundary surface with respect to the normal to the working surface・・・
・Downward angle of the boundary surface with respect to the normal to the operating surface Applicant: Kawasaki Steel Corporation Agent Patent Attorney Yoshio Kosugi No. 11] Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. In the refractory lining of a molten metal container in which the two-part slag line zone wall and the lower molten metal bath zone wall are constructed of refractories made of different materials, the interface between the refractories made of different materials. A refractory lining method for a molten metal container, characterized in that the refractory is joined at a downward angle with respect to the normal to the operating surface of the refractory. 2. The method according to claim 1, which uses a refractory made by integrally joining and molding refractories of different materials at a boundary surface that is inclined with respect to the normal to the operating surface of the refractory.