JPH0382705A - Method for repairing converter in hot-state - Google Patents

Abstract

PURPOSE:To repair damaged part in a converter in hot-state by charging MgO series refractory into the remaining molten slag while injecting bottom blowing gas from a bottom blowing tuyere, spraying water and cooling the converter after sticking the above refractory to the damaged part in the furnace by tilting the converter. CONSTITUTION:When the refractory in the furnace at raw material charging side and steel tapping side in the top and bottom combined blowing converter erodes, while injecting the bottom blowing gas into the furnace with the molten slag after tapping molten steel left remaining in the ratio of 0.1-3.0Nm<3>/min from the bottom blowing tuyere, the waste brick having 30-100mm size, of MgO-containing refractory brick, such as magnesia brick, magnesia-chromite brick, dolomite brick, is added at 10-100wt. parts per the 100wt. parts of the remaining molten slag in the furnace. Then, this is kneaded with the molten slag, and while tilting the furnace, this is stuck to the damaged part, and by spraying the water, this is cooled, solidified and stuck to thickness of <=90% the refractory thickness at the time of laying bricks and repaired at the time of repairing the furnace.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for hot repair of a converter, and particularly to a method for repairing a refractory lining of a converter having a bottom-blowing function, and is widely used in the steelmaking field. Ru.

[Conventional technology]

Hot repair methods for converters include, for example, a hot spray repair method in which monolithic refractories are sprayed with a gun, and a baking repair method in which pitch-containing monolithic refractories are poured into the damaged area and burned using the heat retained in the furnace or a burner. .

A slag coating method is known in which dolomite is added to the slag remaining in the furnace after steel tapping, and the furnace is tilted so that the slag is sprayed onto the furnace wall.

However, since the hot spray repair method basically uses water as a solvent, hot repair involves rapid evaporation of water, resulting in low adhesive strength between the spraying material and the object to be adhered, and a short remaining life. Therefore, it is less effective for steel types that require high-temperature tapping.

Next, the baking repair method uses pitch, tar, etc. as a binder, and takes the process of softening → filling → hardening due to the heat retained in the furnace.
Therefore, the structure has a high porosity due to the volatile substances contained in the organic binder, and has the disadvantage of low corrosion resistance. These conventional hot repair methods have problems with corrosion resistance, and the durability of the repair agent is about 10 cycles at most. Therefore, the frequency of repairs is high,
There is a problem in that the operating rate of the converter is forced to decrease, leading to an increase in repair costs and a decrease in productivity.

On the other hand, the slag coating method, in which slag used in smelting is adhered to and solidified on refractories, has the advantage of not requiring new repair agents and can be used for large-scale repairs; Since the point is the scouring temperature, there is a limit to the number of charges that can be used.

To solve this problem, the remaining slag is mixed with converter auxiliary materials such as dolomite to raise the softening point of the slag and cooled to improve efficiency.

The softening point cannot be raised sufficiently, causing cracks in the attached slag layer, and good results are not always obtained.

In addition, Japanese Patent Publication No. 50-40364 describes a converter repair method in which a refractory or refractory raw material is mixed with residual slag to cool and solidify the converter slag. Special Publication No. 61-59364 is known. The former is a repair method in which a mixture of 20 to 100 parts by weight of a large-sized material or refractory material adjusted to an average diameter of 30III or less is attached to the melted part and cooled and solidified to 100 parts by weight of fluid converter slag. The latter is a repair method in which 5 to 20 parts by weight of a bulk basic refractory having a size of 100 to 200+ am is added to 100 parts by weight of molten slag, and then the slag is stabilized and maintained.

However, with any of these methods, the repair effect is small when the steel bath is stirred extensively, such as in the top-blown converter that has become popular in recent years, or when the tapping temperature reaches 1,700°C, and the durability is only 10~10°C. It is about 20 pieces. Furthermore, when repairing the bottom of a furnace with a recent bottom blowing function using these methods, a strong repair layer can be obtained, but during blowing after repair, the stirring function of the steel bath due to bottom blowing deteriorates, and the top bottom softens. The disadvantage was that economic profits were reduced.

[Problem that the invention seeks to solve]

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a hot repair method that has excellent durability and does not reduce the effect of top and bottom blowing during blowing, even in a converter having a bottom blowing function. .

[Means and operations for solving the problems] The gist of the present invention is as follows.

That is, in a hot repair method for the lining refractory of a converter having a bottom-blowing function, a pressure of 0.1 to 3,0 N is applied from the bottom of the furnace.
The size is 30 to 100 parts by weight of the molten slag left in the converter while flowing bottom blowing gas of m'/win.
This is a method for hot repair of a converter, which is characterized in that 10 to 100 parts by weight of a 100 mm block of large MgO-containing material is charged, the converter is rocked, and then left to stand still.

The present invention is applied to top-blown converters and bottom-blown converters.

It is a converter having a bottom blowing function such as a top and bottom blowing converter and an AOD furnace. When repairing the furnace, first, repair is carried out while flowing an appropriate amount of bottom blowing gas from the bottom of the furnace in order to prevent a decrease in the bottom blowing effect during blowing after the repair. Gas bottom blowing during repair varies depending on the furnace volume, the diameter of the bottom blowing nozzle, the number and arrangement of nozzles, but it is necessary to install a "r gas path" with an appropriate porosity directly above the nozzle in the repair layer that forms at the bottom of the furnace. Bottom-blown gas is flowed into the furnace from a predetermined position so as to generate gas.

The amount of bottom blowing gas during repair is 0.1 to 3,0 Nm3/w
The range was limited to in. The reason for this is that the flow rate is 0.1Nn+
If it is less than "/mfn," it is difficult to create a gas path J, and the bottom blowing gas cannot be injected from a predetermined position due to the gas pressure loss within the repair layer during blowing, and during blowing after repair, it is difficult to create a gas path J. The effect decreases significantly.Also, when the flow rate is 3,0 N1/
This is because if it exceeds 11 inches, the porosity of the repair layer above the nozzle becomes excessive, reducing the effect of repair.

In this way, the MgO-containing refractory in the form of a lump is introduced into the molten slag remaining in the converter while blowing gas from the bottom of the furnace, and the converter is rocked to mix the molten slag and the MgO-containing refractory. do.

The amount of the block MgO refractory to be charged is limited to 10 to 100 parts by weight per 100 parts by weight of the remaining molten slag. The reason for this is that if it is less than 10 parts by weight, there will be too much binder, the surface layer of the solidified slag in the repair layer will melt, and the bulk refractories will easily flow out, resulting in a marked decrease in durability; This is because if it exceeds 100 parts by weight, there will be a shortage of binder and the bonding force will be weak, causing the repair layer to collapse and fall off when the furnace is tilted, reducing the repair effect.

The bulk MgO-containing refractories used in the present invention are general basic bricks such as magnesia bricks, mag-black bricks, dolomite bricks, and magnesia-carbon bricks, and these water-resistant materials as well as broken bricks and recovered after use. Bricks can be used.

In addition, the size of the pre-massive MgO refractory used is 30 to 1
Limited to 00ffll. If the number of questions is less than 30, the solidified slag in the repair layer will melt and the refractories will easily flow out, reducing the effectiveness. In addition, if the size exceeds 100 mm, it becomes difficult to mix the molten slag with uniform dispersion, and the portion of the slag alone, which is a binder, becomes large, and this portion melts at high temperatures at the end of blowing, reducing the bonding effect and reducing the bonding effect of the molten slag. This is because the repair layer will be eroded by the flow, and will easily collapse and fall off when the furnace is tilted.

When the mixing of the molten slag and the lumpy refractories is completed by the shaking as described above, it is allowed to stand still with the bottom blowing gas flowing. There is no particular stipulation regarding the standing time, but it is generally determined by the amount of slag,
It depends on the viscosity and amount of refractory lumps, but in any case, it is necessary to let the slag stand for a period of time from a fluid state until it solidifies, and in most cases, 30 minutes or more is required. be.

Sprinkling water on the repaired area while it is standing still to cool it has the effect of shortening this standing time, and depending on the thickness of the repair layer formed, spraying water reduces the solidification time by 10% compared to when no water is sprinkled.
The time can be reduced by about a minute.

The above-mentioned repair method according to the present invention can be applied not only to the furnace bottom but also to the core of the converter on the tapping side and the charging side.

In this case, it is possible to reduce the rate of erosion of the refractory in this part to 90% or less compared to the other part of the trunnion side of the furnace. In conventional converters, the thickness of the refractory in the furnace belly was the same, but by applying the method of the present invention, the thickness of the refractory in the furnace belly on the charging side and the tapping side can be changed at the time of furnace construction. By setting the thickness to 90% or less, it is possible to have a uniform residual thickness of the refractory at the end of the furnace life, thereby increasing the utilization efficiency of the refractory.

〔Example〕

During hot repair of the bottom of a top-bottom blowing converter (LD-KGC), 180, which performs blowing at a tapping temperature of around 1,650°C, was operated while flowing bottom-blowing gas of 2.0 Nm''/aim from the bottom of the furnace. Recovered magnesia carbon bricks in the form of blocks of 50 to 90 mm in size were charged from the scrap chute to 5 tons of residual molten slag after tapping, and after shaking the converter to mix it, the furnace was turned vertically and allowed to stand still for 40 minutes. I installed it and repaired it.

After the main repair, more than 50 layers of the repair layer remained, and the bottom blowing effect did not deteriorate during the blowing after the repair.

Figure 1 shows the relationship between the number of heats and the remaining thickness of the furnace bottom when hot repair is performed by the method of the present invention every 50 heats. be able to.

〔Effect of the invention〕

As is clear from the above embodiments, the present invention provides a hot repair method for a converter having a bottom-blowing function, in which a predetermined amount of lumpy MgO-containing refractory is applied to residual slag while flowing bottom-blowing gas from the bottom of the furnace. Insert.

After shaking, a strong repair layer was formed by allowing it to stand still, resulting in the following effects.

(a) It is now possible to operate more than 50 wheels per repair, reducing the number of repairs, reducing repair costs and improving productivity.

(b) Since excellent hot repair has become possible, the thickness of refractory construction at the time of furnace construction has been reduced to approximately 30% less than before at the furnace bottom, charging side, and furnace side on the tapping side, where the one-line repair method can be applied. 40%
It becomes possible to decrease.

Furnace construction costs were significantly reduced.

(c) In blowing after repair, it was possible to prevent the lowering of the bottom blowing effect caused by conventional repair methods, and to enjoy the economic benefits of top and bottom blowing.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the number of heats and the remaining thickness of the furnace bottom of the converter according to the embodiment of the present invention.

Claims (3)

[Claims] (1) In a hot repair method for the lining refractory of a converter with a bottom-blowing function, 0.1 to 3.0 Nm^3/
The size is 30 to 100 parts by weight for 100 parts by weight of molten slag left in the converter while flowing bottom blowing gas of min.
1. A method for hot repair of a converter, which comprises adding 10 to 100 parts by weight of MgO-containing refractories in the form of blocks of mm, shaking the converter, and then allowing it to stand still. (2) Claim (
1) Hot repair method for a converter as described. (3) When the repair method is applied to the converter charging side and the steel tapping side of the furnace belly, the thickness of the refractory material in these areas is 90% or less of that of the other furnace sides (1) or (2). ) Hot repair method for converter as described.