JPH01118362A - Treatment of refractory brick surface of molten metal vessel - Google Patents

Abstract

PURPOSE:To extend the service life of a refractory brick by lining castable refractory after applying alumina coating on surface of the permanent lined refractory brick at inside of permanent lined castable refractory at shell side of a vessel as the lining refractory material in the vessel for molten metal. CONSTITUTION:The side wall permanent lined castable refractory 1 contacting with the iron shell 4 of the vessel for molten steel of ladle, tundish, etc., is lined and at inside thereof, the side wall permanent lined refractory brick 2 of agalmatolite brick, etc., is lined in the inside thereof. Successively, after applying alumina series mortar 9 on the surface at 2-5mm thickness, the alumina series mortar 9 is fixed to the refractory brick 2 by burning at about 1450 deg.C for 60hr. By using the mold flask on the surface of the alumina series mortar layer, the castable refractory is filled up by the flowing method and the mold flask is removed and burnt to form the castable refractory layer 1. At the time of repairing caused by erosion of the castable refractory, the refractory brick 2 is not broken with existence of the alumina series mortar layer 9, use of the refractory brick 2 is born for long time together with the permanent lined refractory 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for surface treatment of refractory bricks in molten metal containers in order to increase the number of uses of metal containers used in the steel industry and to improve the unit consumption of refractories. .

[Prior Art] The molten metal container referred to in the present invention is a container for accommodating high-temperature molten metal such as molten steel for reaction treatment, and includes, for example, a ladle, a tundish, a vacuum degassing container, and other high-temperature processing containers. These containers generally have sidewalls and a bottom, each lined with a refractory material, which in turn consists of a permanent liner and an inner liner. Of these, the permanent lining is built on the outside of the container (the steel skin side), and the inner lining is built on the inside of the container (the side that comes into contact with molten steel). This is specifically shown in FIG. 3, which is a vertical sectional view of the side wall of a conventional ladle. 1 is castable with permanent side wall lining, 2 is brick with permanent side wall lining, 3 is side wall lining,
4 is a diagram showing the iron skin. FIG. 4 is a plan view of the side wall of the ladle.

On the other hand, the inner lining 3 of the side wall is made of cast-in monolithic refractory material and is easily damaged by molten steel and slag.
Repairs are being carried out after using the charge. On the other hand, side wall permanent bricks 2 have been used for many generations. In the case of side wall permanent brick 2, it is normal that it has been used for about one year. For the side wall permanent bricks 2, waxite bricks are used due to their thermal conductivity, durability, and economical efficiency. The lining 3 of the side wall is a cast monolithic refractory and is mainly made of zircon in consideration of its resistance to erosion with molten steel. The pouring construction method is
A side wall "permanent tension castable 1" and a permanent tension castable castable 8 are constructed in the molten metal container, and then a side wall permanent tension brick 2 and a reinforcement brick 5 are constructed. After that, a metal cylindrical object is inserted into the molten metal container. , pour a cast monolithic refractory between the side wall permanent brick 2 and the metal cylinder (form).After 4 hours of construction, the cast monolithic refractory hardens and the metal cylinder (form) is inserted. This method involves taking out the molten metal frame (frame) from the molten metal container.

[Problems to be Solved by the Invention] However, when pouring monolithic refractories are applied to the lining 3 of the side walls and demolishing them after using 50 to 60 charges, the cast monolithic refractories adhere to the side wall permanent lining bricks 2. Therefore, when demolishing the poured monolithic refractories attached to the side wall permanent tension bricks 2 using a demolition machine (such as a pre-car), the side wall permanent tension bricks 2 will be damaged and the side wall permanent tension bricks 2 will have to be replaced. It won't happen. Also, the fifth
As shown in the figure, deposits 6 of cast-in monolithic refractories remain on the surface of the side wall permanent tension bricks 2 after repair, and after that, a metal cylindrical object is inserted into the molten metal container, and the side wall permanent tension bricks are 2 and a metal cylindrical object, and after heating and drying, it receives molten steel and uses it for about 40 charges, and the remaining thickness b of the poured monolithic refractory becomes the cast monolithic refractory. When the thickness of the object becomes about 1/8 of the original thickness a, a crack 10 appears in the remaining cast monolithic refractory starting from the convex part 7 of the cast monolithic refractory left over from the previous time, and The poured monolithic refractories peeled off,
There was a problem of going back to spraying repairs and repairing pots. This invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for surface treatment of refractory bricks of molten metal containers in order to improve the number of times of use of metal containers used in the steel industry and the unit consumption of refractories. purpose.

[Means for Solving the Problems] The present invention provides a metal container in which the outer layer of the side wall is made of a pourable monolithic refractory material and the inner layer is made of refractory bricks, and the inner layer is made of an alumina-based material on the surface of the refractory bricks. It is characterized by being coated or sprayed.

[Function] Alumina-based coating materials have good adhesion when hot, but when cold, the adhesion weakens, and the bond between the castable monolithic refractory and the refractory brick becomes weak. In addition, it has the property of being strong against monolithic refractories and firebricks made of the same material, but weak against materials of different materials. Taking advantage of these properties, it is preferable to apply an alumina-based coating material to the surface of the refractory brick (the side of the castable monolithic refractory).

[Examples] Examples of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a diagram showing a longitudinal cross-sectional view of the side wall of the ladle of the present invention. FIG. 2 is a diagram of an embodiment of the present invention in which the aluminum coating is applied to a firebrick with permanent side walls. Tables 1 to 3 are composition lists of the refractories used in this example. Table 1 shows the composition of the alumina-based coating material, Table 2 shows the composition of the cast monolithic refractories, and Table 3 shows the composition of the side wall permanent refractory bricks.

Table 1 Table 2 Table 3 (Example 1) After forming the side wall permanent refractory bricks 2 (lowite bricks), alumina mortar 9 was applied to 2 to 5 mm of the side wall permanent refractory bricks 2 (lowite bricks). It is applied to the surface (poured monolithic refractory side) and fired in a firing furnace (tunnel kiln type) at 1450''C for 60 hours to ensure adhesion between the alumina-based mortar 9 and the side wall permanent refractory brick 2 (lowstone brick). , forming a surface layer.

Then, 300 pieces of this fired side wall permanent tension refractory brick 2 were added.
It was used as a T on ladle, and the monolithic refractory 11 was poured into the inside of the ladle, and then molten steel was received. Then, the work of demolishing the cast monolithic refractories 11 at the time of repair became easy, and the cast monolithic refractories 11 did not adhere to the side wall permanent refractory bricks 2 (lowstone bricks) at all.
Furthermore, no peeling of the monolithic refractories 11 occurred during the pouring of molten steel into the receiving steel.

(Example 2) After molding the side wall permanent refractory bricks 2 (lowite bricks), alumina-based thermal spraying agent 9 was applied to the surface of the permanent wall refractory bricks 2 (lowite bricks) to a thickness of 2 to 5 mm ([!I). Shaped refractory 1
1 side). The thermal spraying conditions at this time are shown in Table 4. An actual machine test was conducted using the same 300T on ladle as in Example 1.

Table 4 Conventional method and Example 1. A comparison with Example 2 is shown in Table 5.

As is clear from these results, there were almost no problems with workability or peeling of bricks after repair.

Table 5: The reason for the numerical limitation in this invention is that if it is less than 2 mm,
Peelability of the cast monolithic refractories 11 from the sidewall permanent bricks is not good, and if the thickness exceeds 5 mm, the cost will be high. In particular, when alumina-based materials are thermally sprayed onto the surface of refractory bricks, since the material is thermally sprayed at a high temperature, if the material is thermally sprayed over 7 mm, the bricks will warp, resulting in gaps.

Although this example shows an example of coating on one side, the same effect can be obtained by coating on both sides.

[Effects of the Invention] By carrying out the present invention, problems such as peeling of cast monolithic refractories and damage to permanent side wall refractories did not occur. It is possible to improve the number of sustained sessions and the basic unit.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the side wall of a ladle of the present invention, Fig. 2 is a view of an embodiment of the aluminum coating of the present invention applied to a permanently stretched refractory brick, and Fig. 3 is a view of the side wall of a conventional ladle. 4 is a plan view of a conventional ladle side wall, and FIG. 5 is a longitudinal sectional view of the conventional ladle side wall during use. 1... Castable with permanent side wall tension, 2... Brick with permanent side wall tension, 4... Iron skin, 9... Alumina coating material, 11... Poured monolithic refractory.

Claims (1)

[Claims] A metal container whose outer layer of the side wall is a pourable monolithic refractory and whose inner layer is a refractory brick, characterized in that the surface of the refractory brick of the inner layer is coated or thermally sprayed with an alumina-based material. Surface treatment method for refractory bricks for containers.