JPH09279217A - Slag coating method into molten metal vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slag coating method for coating and protecting a refractory lining material forming the inner wall of a molten metal vessel with remaining molten slag after tapping the molten metal or in the condition of remaining the molten metal without tapping full quantity of the molten metal. SOLUTION: Solid powder having <=2mm grain diameter is blown into the vessel from a bottom-blown tuyere into the remaining molten slag after tapping the molten metal from the molten metal vessel or in the condition of remaining the molten metal without tapping the full quantity of molten metal and dipped into the molten slag, and inert gas or reducing gas is brown from a top-blown main lance or the bottom-blown tuyere to develop the splash in the vessel, and the slag coating is executed on the inner wall of the vessel. As the solid powder, lime, clcined magnesia or dolomite is suitable, and by this method, the slag coating layer having high durability can be formed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a refractory lining material forming an inner wall of a molten metal container such as a smelting reduction furnace, a scrap smelting furnace, and a hot metal pretreatment furnace, which is left after tapping or without tapping the entire amount. In this state, the present invention relates to a slag coating method for coating and protecting with molten slag that remains.

[0002]

2. Description of the Related Art Generally, in a smelting reduction furnace, a scrap melting furnace, a hot metal pretreatment furnace, etc. used in a pig iron process of a steel manufacturing process, reaction with slag at high temperature, wear due to hot metal or molten steel flow, or heat Due to spalling etc. due to impact, MgO-C bricks and Mg which are refractory linings
O-Cr ₂ O ₃ bricks and the like are greatly worn. Due to such wear of the refractory lining, the life of the container lined with the refractory is shortened and not only the cost of the refractory is increased, but also much labor and time are required to restore and construct the refractory lining. , Productivity is also reduced.

With respect to the wear of such refractory lining,
Hot spray repair method that sprays irregular shaped refractory with a spray gun, bake repair method that heats the repair material to the damaged part with furnace heat using a thermosetting resin such as pitch or resin as a binder, powder in a high temperature frame Generally, a thermal spray repair method, etc., in which a damaged portion is repaired by melting it by the method described above. But,
All of them had problems such as requiring a lot of time and labor for repair, and high material costs.

On the other hand, various slag coating methods have been proposed which do not require time and labor and do not use expensive materials. This slag coating method is a method in which the molten slag remains in the container even after the molten metal is tapped, and the slag is coated on the inner wall or bottom of the container.By tilting the container, the residual slag is coated on the inner wall by tilting. Repair method, JP-A-59-938
The blow-up repair method described in JP-A No. 16-62, in which the slag is blown off in the form of a splash using the bottom blow-off mouth, and is coated, is described in JP-A-61-56223 and JP-A-62-17112. There is a top-blown repair method in which the slag is blown off in a splash form using the top-blown main lance for coating.

[0005]

Of these, the tilting repair method can sufficiently coat the inner wall in the charging and discharging directions that coincide with the tilting direction, but the trunnion side cannot be coated, and spray spraying repairing is possible. There was a drawback that it was forced to use together. On the other hand, the blow-up repair method and the top-blown repair method have an advantage that the entire container can be coated.

However, in the case of these methods, since the heat capacity of the container is large, the scattered slag is hard to adhere without solidifying, and even if it adheres, the softening and melting temperature of the coating layer is low, so that it is easy to remelt. There were problems such as low durability. To solve the problem that the slag does not solidify and adheres easily, an attempt is made to improve the slag adhesion by adding a slag modifier to increase viscosity and basicity in JP-A-61-56223. Attempts have been made to do so.

However, in this method, since the lump-like slag modifier is charged from the furnace opening, the slag slagging property is deteriorated and the slag layer is separated into a hard slag layer and a soft slag tank, and splash is generated. However, there are still problems such as the difficulty of occurrence and the high cost because a large amount of modifier is required. Further, JP-A-5-331518 proposes a method of spraying a high-pressure gas containing oxygen of 25% or less for the purpose of ensuring the slag slagging property after the addition of the slag modifier.

However, when an oxidizing gas containing oxygen such as air is used, Fe remaining in the container reacts with oxygen to produce FeO, which causes further damage to the refractory. However, none of them is a method for improving the solidification and adhesion of the slag. On the other hand, with respect to the problem that the durability of the coating layer due to the adhered slag is low, Japanese Patent Application Laid-Open No. 3-68712 discloses a method of evenly dispersing brick blocks in the slag during furnace bottom coating. However, according to this method, it is difficult to attach block bricks to the inner wall of the container while the container is upright.

The present invention has been made in view of these problems, and forms a highly durable slag coating layer mixed with powder solids so that the residual slag can be uniformly and firmly adhered to the inner wall of the container. The purpose is to provide a method of doing so.

[0010]

That is, the gist of the present invention is that after molten metal is tapped from a molten metal container,
Alternatively, in a state where the entire amount of hot water is left without being tapped, solid powder having a particle size of 2 mm or less is blown into the container from the bottom blowing tuyere into the molten slag remaining in the container, and is taken into the molten slag, Slag coating of a melting or refining container characterized by injecting an inert gas or reducing gas from the top blowing main lance or bottom blowing tuyere to generate a splash in the container and coating the inner wall of the container with slag. On the way. At this time, in particular, the solid powder is quick lime, light burned magnesia, or dolomite, and a compound that raises the softening melting temperature of the slag coating layer is suitable. By using such solid powder, it is possible to form a coating layer having a higher durability in which slag and solid powder are mixed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, when an inert gas or a reducing gas is blown into a container from a top blowing main lance or a bottom blowing tuyere, a solid powder having a particle diameter of 2 mm or less is generated when a splash is generated. Blow from the tuyere,
Dissolve or suspend uniformly in the molten slag. As a result, the generated splash adheres to the furnace wall while containing the solid powder. At this time, since there is a temperature difference between the solid powder and the slag, the slag is cooled, its fluidity is weakened, and it easily adheres to the inner wall of the container. In the method of the present invention,
A relatively fine solid powder of 2 mm or less is blown into the residual slag, so it is evenly dispersed in the molten slag, and deterioration of slag formation and separation of the molten slag do not occur, so a stable splash occurs. However, the amount of solid powder is small, which is economically advantageous. On the other hand, the reason why the particle size of the solid powder is 2 mm or less is that if the particle size exceeds 2 mm, it becomes difficult to convey the solid powder to the bottom blowing tuyere. The surface of the solid powder particles taken into the slag coating layer partially reacts with the slag, but part of the surface remains solid. Therefore, when the slag coating layer is remelted, the solid particles serve as nuclei to exert the spike effect,
The durability is improved. As the type of solid particles to be added, quick lime, light burned magnesia, or dolomite is desirable. Since the melting point of these solid particles is as high as 2000 ° C. or higher, the softening and melting temperature of the slag coating layer is increased, and slag coating with high durability becomes possible. N as the gas blown from the top blowing main lance or the bottom blowing tuyere
Any inert gas or reducing gas such as ₂ , Ar, He, CO or CO ₂ may be used.

[0012]

[Example] After slag was melted in a 100T scrap melting furnace, the entire amount of slag was left (15T) and 30,000 Nm ³
The test was conducted by spraying N ₂ of / H from the main lance for 2 minutes. The test conditions are as shown in Table 1. The solid powder is 10 from the bottom tuyere with N ₂ as a carrier gas.
It was blown at a speed of 0 kg / min. After that, the furnace was tilted, the remaining molten slag was discharged, and then the thickness of the slag adhering to the trunnion-side furnace tilt portion was visually measured. Further, the number of durable channels until the adhered slag coating layer was peeled off was also investigated. The results are shown in Table 1.

[0013]

[Table 1]

[0014]

As is apparent from Table 1, the solid powder added according to the present invention has a deposited slag thickness of 3 to 4 times and durability c compared to the conventional solid powder not added.
The h-number increased 3 to 5 times. By carrying out the present invention, it is possible to drastically reduce the frequency of spray repair that has been conventionally carried out, and not only the cost of the furnace material can be reduced but also the production capacity can be improved by extending the life of the furnace.

Claims (2)

[Claims] 1. A molten metal slag remaining in the container after the molten metal is discharged from the molten metal container, or in a state where the entire amount of the molten metal is left without being discharged, and the particle diameter is 2 mm or less from the bottom blowing tuyere. The solid powder of is blown into the container, taken into the molten slag, inert gas, or reducing gas is blown from the top blowing main lance or bottom blowing tuyere to generate a splash in the container and to the inner wall of the container. A slag coating method for a molten metal container, which comprises slag coating. 2. The method for slag coating a molten metal container according to claim 1, wherein the solid powder is quicklime, light burned magnesia, or dolomite.