JPS58117816A - Hot repairing method for converter - Google Patents

Abstract

PURPOSE:To carry out repairing guaranteeing a long endurance life by charging a specified amount of basic refractory blocks having a specified size into molten slag remaining in a converter to hold the slag in a killed state. CONSTITUTION:When the wall of the charge side of a converter is hot repaired, about 2/3 of produced slag is discharged after discharging steel. Basic refractory blocks having 50-400mm., especially 100-200mm. size are charged by 5-20pts.wt. per 100pts.wt. remaining molten slag, and the slag is cooled, stuck to the molten part and solidified to carry out repairing. Magnesia brick, magnesia-chrome brick, dolomite brick, magnesia-carbon brick or the like is used as the basic refractory. The endurance life of the converter repaired by this repairing method can be elongated by >=10 times of a converter repaired by a conventional repairing method.

Description

Detailed Description of the Invention Hot repair methods for converters include, for example, hot spray repair methods in which monolithic refractories are sprayed with a gun, pitch-containing monolithic refractories are injected into damaged areas, and Seizing repair methods involve baking with heat or a burner, and furthermore, tilting the furnace back and forth with the molten slag left in the furnace after tapping, or applying external force to the slag to spray the slag onto the furnace wall. Slag coating methods and the like are widely known.

These repair methods, along with improvements in both the monolithic refractories and construction equipment used, have become widespread in converter factories to the point where they are not only able to perform local repairs, but also completely repair the inside of the furnace, greatly extending the life of the furnace. I'm coming. However, spray repair methods are generally classified as dry methods or wet methods depending on when water is added, but since water is basically used as a solvent, when used in hot conditions, vapor pressure decreases due to rapid evaporation of water. This has the drawback of causing deterioration of the adhesive strength between the sprayed material and the object to be adhered, and further deterioration of the structure. In addition, the baking repair method uses organic binders such as pitch and tar as the main binder, and uses the heat retained in the furnace to soften, fill, and harden the process, and basically does not use water, so the above drawbacks are alleviated. However, it has the disadvantage that the structure becomes poor and the corrosion resistance deteriorates due to the generation of decomposition gas due to heating of volatile substances contained in the organic binder.

In addition, in the slag coating method, a slag layer that solidifies and adheres to the furnace wall surface protects the object to be adhered to, but the formed slag layer has a lower melting point than the molten steel during blowing, so it is easily remelted. It has the disadvantage of very low durability.

As described above, all of these methods have problems with their durability, and depending on the degree of repair, the durability of the repair material is about 1ch.
, (charge) to at most 3 ch, (charge). Therefore, in any converter factory, repairs must be carried out very frequently, and the operating rate of the converter is forced to decrease due to repairs. This not only increases the cost of repair materials, but also poses a problem in the operating process, especially in steel factories where CC has been adopted, resulting in a decrease in steel productivity.

The present invention is intended to provide a means for greatly improving the repair effect, which is the biggest drawback of conventional repair methods. The gist of this is to repair the charging wall, tapping wall, and furnace bottom parts of the converter, which are most severely damaged by melting, using 1 part by weight of molten slag left in the furnace and 0.0 parts by weight of the bulk basic refractory material. 05-0.2
This is a hot repair method for converters characterized by coating with parts by weight.

Specifically, when repairing the charging wall, tapping wall, and furnace bottom,
After leaving a predetermined amount of molten slag in the furnace and tilting the furnace so that the repaired area is almost horizontal, a block of basic refractory material is introduced, and the remaining slag is used as a binder to cool and solidify the slag to form a strong construction body. can get. It is generally necessary to hold the bulk refractory material for 15 minutes or more until it fully penetrates into the slag and solidifies. The repaired body thus obtained has a state in which the lumpy refractory materials are intertwined with each other, and the gaps between the refractory materials are filled with solidified lag, forming an integrated structure of rare lumpy refractory material and solidified slag. The structure is firmly adhered to the converter lining refractory by slag.

Japanese Patent Publication No. 50-40364 ``Converter Repair Method'' is known as a converter repair method in which a refractory or refractory raw material is blended with such fluid converter slag and the converter slag is cooled and solidified. ing. This method uses fluid converter slag 1
This is a repair method in which a refractory adjusted to have an average diameter of 3,011,111 parts by weight or less or a material containing 0.2 to 1.0 parts by weight of a large raw material is attached to the melted part and cooled and solidified. The repair method described in the patent claims of the publication applies, for example, to cases where a large converter of 300 or more steel is used and the tapping temperature reaches around 1,700°C, and when a complex blowing furnace that performs strong stirring of the molten steel flow, which has become popular in recent years, is used. It has no effect at all in furnaces, etc., and its durability is at most 2 channels.
, it was about.

The cause of this is that in the integral structure of lump refractory material and solidified slag, even if the strength of the slag at the bond part is small, the lumps (with fire resistance and corrosion resistance of more than a certain size and SOW) This is because, if the material is not made of material equivalent to bricks, the lumpy refractory material and the solidified slag, which has a melting temperature of around 1450° C., will be melted away almost at the same time. As a countermeasure, we investigated the shape and amount of bulk basic refractory material.
We were able to find a new optimal range.

The bulk basic refractory materials specified here are magnesia bricks, mag black bricks, dolomite bricks, magnesia bricks, and magnesia bricks.
Made of general basic bricks such as carbon, they can be used not only as finished products but also damaged and used bricks.
400 m/m blocks are used, but preferably 100~
A lump of 200 Ill size is good. If the shape of the brick is extremely small or large, for example if it is a lump smaller than 50 mm, it will not penetrate into the slag sufficiently and will be washed away by the flow of molten steel during blowing, or if it is larger than 400 *il. If it becomes a lump, there is a risk that it will flake off and fall under its own weight when the furnace is tilted. Also, the amount of bulk basic refractory material is reduced to 1
The reason for specifying 5 to 202 parts by weight or less for 00 parts by weight is that if the lumpy refractory material is less than 5% of the slag thickness, no effect on durability can be expected, and if it is more than 20%, the binder effect of the slag is small and it will not be effective when tilting. Collapse and fall off. Therefore, it is necessary to specify the amount of bulk refractory to be added so that the height is 5 to 20% of the slag thickness.

Adding lime (limestone grains or calcined lime grains) or dolomite (dolomite grains or calcined dolomite grains) to the molten slag helps to increase the viscosity of the slag and increase the melting temperature. It is preferable to add these when the melting temperature of the solidified slag needs to be raised before high-temperature blowing.

The addition ratio of these additives to the slag is preferably 0.2 parts by weight or less; if it is more than that, the fluidity of the molten slag will be lost. The settling time of 15 minutes or more depends on the amount and viscosity of the slag, the presence and amount of additives, the amount of bulk refractory material, etc., but in any case, the slag will solidify from a fluid state. It takes time for the refractory to cool down, and in many cases, 15 minutes or more is required, and if the time is shorter than this, the lumpy refractory may fall off. Note that the converter referred to here refers to a top-blown converter, a top-bottom converter (combined converter), a bottom-blown converter, an AOD furnace, etc. When tilted at a predetermined angle, it can form a nearly horizontal state. It can be applied to parts.

〔Example〕

When performing hot repairs on the charging side wall of a 320 steel steel that undergoes blowing at a tapping temperature of around 1,670°C, 20 tons of the approximately 30 tons of slag produced after tapping the converter were removed, and the remaining 10
1 was left in the furnace and 1 ton of raw dolomite was put in. Next, the furnace was tilted to the front side of the furnace so that the above repaired part was horizontal, and then the used brick It was put into the above repaired part using the scrap chute, and it was left as it was. The condition was maintained for approximately 30 minutes and the repair was completed.

It was confirmed that the repaired area remained until the time of j5ch.

As mentioned above, the hot repair method according to the present invention is
Compared to the repair method in Publication No. 40364, it has a lifespan of more than 10 times, eliminates the need for sizing of bricks, reduces repair costs, and improves converter operation rate due to long-term slag resistance. It greatly contributes to improving overall productivity and productivity.

Procedural amendments February 2, 1980 Commissioner of the Patent Office 1) Haruki Tono 1 Display of case 1982 Patent Application No. 210908 2 Title of invention Method for hot repair of converter 3 Case of person making amendment Relationship Patent applicant address 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name
(665) Nippon Steel Corporation Representative Takeshi 1) Yutaka 4th Director Masato 105 Telephone (503) 48776 Number of inventions increased by amendment 0 7 Subject of amendment Column 8 for detailed explanation of the invention in the specification Contents of the amendment (1) On page 3, line 16 of the specification.

It says, "With 1 part by weight of molten slag."

Corrected to "molten slag 100N'j# part".

(2) In line 17 of the same.

The phrase "...0.05 to 0.2 parts by weight..." is corrected to "...5 to 20 parts by weight...".

(3) On page 4, line 17 of the specification, it says "...1 part by weight of converter slag...".

Corrected to "...100 parts by weight of converter slag...".

(4) On lines 18 and 19, it says "...0.2 to 1.0 parts by weight...".

Correct to "...20~loo] i lid part...".

(5) E! On page 6, line 8 of Book A, “...
・5 to 202 parts by weight..."

Correct to "...5 to 20 parts by weight...".

(6) Specification #, page 7, line 1, It says "...the addition ratio is 0.2".

Correct the addition ratio to 20.

Claims (1)

[Claims] When repairing the refractory lining of a converter, 50 to 4 parts by weight of molten slag left in the converter
1. A hot repair method for a converter, which comprises charging 5 to 20 parts by weight or less of a bulk basic refractory having a size of 0.00 m/m, and then calming and holding the refractory.