JPS61157611A - Slag coating method of converter - Google Patents

Abstract

PURPOSE:To prolong the furnace life and also to decrease the suspension time of a furnace accompanied with the titled coating and the consumption of a slag modifying agent or the like by bonding and laminating sufficiently a slag coating layer on an inside wall surface of a furnace. CONSTITUTION:After the tapping of a coverter 3 executed with a refractory 2, a modifying agent such as delomite is added to the residual slag 4 in the inside of the converter 3 and a slag coating layer 6 is formed on an inside wall surface 7 by blowing gas such as Ar and N2 through the tuyeres 5 and dissipating the slag 4. Then a forced-cooling lancer 9 which is provided with plural pieces of liquid spraying nozzles 10a-10f to a tip part 8 of a cylindrical body is vertically hung in the converter 3 freely movably up and down and for example, water as fluid is fed to the lance 9 via a forced-cooling installation and the dissipation is performed through the tip part 8 to cool forcedly the slag coating layer 6. Successively the coating layer 6 laminated by performing the refining of at least one charge and thereafter performing the recoating and the forced-cooling with the same means as the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of slag coating an inner wall surface of a converter.

[Conventional technology]

In general, the cost of refractories accounts for 4% of the cost of refining molten iron in converters such as top-blown, bottom-blown, or top-bottom blowing.
The ratio is extremely large. For this reason, it is important to suppress the wear and tear of the refractory lining of the converter as much as possible to extend its life, and this is considered a technical problem for the workers concerned to solve.

Therefore, as a method for preventing wear and tear on the refractory lining of a converter and extending the life of the furnace body, dolomite is added to the residual slag after tapping refined molten steel to reform the residual slag. , and then coating the inner surface of the furnace wall by simply rocking the furnace body (hereinafter simply referred to as the rocking coating method)
Or, as in Japanese Patent Publication No. 59-38282, gas is blown into the furnace through a tuyere cage installed at the bottom of the converter to blow up the residual slag inside the furnace, and the converter is rocked to coat the slag. A method to do this (hereinafter simply referred to as tuyere blow-up coating) has been proposed. [Problems to be Solved by the Invention] However, as a conventional method, for example, in the above-mentioned rocking coating method, the parts that become horizontal surfaces during rocking on the charging and tapping sides can be sufficiently coated, but the trunnion Coating of the corresponding part (vertical part) is not possible. On the other hand, the above-mentioned tuyere blow-up coating method has the advantage of wide tolerance on the spray surface.

However, in common with the above-mentioned rocking coating method, the slag coating layer on the inner wall of the furnace is simply welded to the brick surface of the inner wall, so almost all of it melts off due to stirring of the molten steel during the refining of the next charge. Therefore, the slag coating must be repeated frequently to protect the inner walls of the furnace.

For this reason, the downtime of the converter itself required for coating increases, resulting in a significant drop in the productivity of the converter, and dolomite added to the residual slag due to repeated coating.
A slag modifier containing magnesia, alumina, or other fire-resistant materials.

Or does it lead to a large loss of tuyere blown gas, etc., and the lifespan of the converter is that the coating layer melts off even during refining, so the lifespan of the culm is longer than expected? It has drawbacks such as the inability to

[Purpose of the invention]

2 The present invention has been made to solve the above-mentioned problem, and is D in that the slag coating layer is sufficiently bonded and laminated on the inner wall surface of the furnace to prevent the slag coating layer from being worn out by the refined molten steel or slag. By making the slag coating layer sustainable for a long time in the present invention, the increase in converter down time and the large consumption of slag modifier and tuyere blowing gas are suppressed, and the life of the refractory lining of the converter is extended. The purpose of the present invention is to provide a slag coating method that can be applied.

[Means for solving problems]

The gist of the present invention to achieve the above object is that after coating the inner wall surface of the converter with residual slag in the converter or slag to which all modifiers have been added, the coating layer is forcibly cooled, and then at least one charge is applied. After refining the
This is a slag coating method for a converter, which is characterized by repeating the D coating to stack the coating layers.

The slag coating method for a converter according to the present invention will be explained below.

The present inventors conducted a glaze-free study and experiment regarding the wear and tear of the slag coating layer, which has been sufficiently coated with the converter inner slag coating material on the surface of the inner wall of the furnace. The present invention was achieved based on the findings obtained as a result.

That is, the present inventors added doloma 4, which is a slag modifier, or aggregates such as magnesia, or refractory materials to the slag remaining after refining and tapping in a converter to impart viscosity to the furnace wall. We investigated the reason why the slag coating layer formed by adhesion is easily removed from the furnace wall during refining even if it is made to adhere easily. As a result, the inventors found that the surface of the slag coating layer is in a semi-molten state and is abraded by the molten steel or slag during refining, and that the slag coating layer immediately after being coated on the inner wall surface has a strong As mentioned above, it was found that in addition to physical wear, elution due to reaction with slag was progressing as much as possible because it was weak in terms of physical strength and the compositional density was also coarse and dense.

The present invention has obtained the following knowledge based on the above-mentioned knowledge; In order to improve the durability of the slag coating layer, it is necessary to use the residual slag in the converter or the slag obtained by adding a modifier to the residual slag. After coating the inner wall surface, the core slag coating layer is forcibly cooled, so that the surface of the slag coating layer shrinks and solidifies to form a hard, dense refractory layer. This hard and dense slag coating layer sufficiently exhibits wear resistance and reaction elution resistance due to molten steel and slag during refining, but the surface layer softens and disappears slightly. Therefore, after the next charge or several charges of refining, with the previous coating layer still remaining, slag coating and forced cooling of the surface layer are performed using the same means as above, and this is repeated to form a slag with an appropriate thickness. Coating layer Lr) Form a laminated layer. By stacking coating layers in this way,
Rather than just a slag coating layer, the coating layer serves as a refractory structural wall and sufficiently protects the furnace bricks of the furnace body.

In addition, due to the fact that the converter itself has no production margin, the coating layer should be laminated multiple times to sufficiently hold the furnace wall when coating time can be secured, and conversely, when there is no idle capacity. Since the plant can be operated mainly by production, coating can be carried out effectively.

As a cooling medium for forced cooling of the slag coating layer, gas fluids such as air, nitrogen, and low-temperature steam, or liquids such as water and oil are used in liquid form or in mist form through spraying, etc. However, by spraying this onto the surface of the aforementioned coating layer, a reinforcing slag coating layer can be effectively formed.

In addition, if this forced cooling is too supercooled, not only the slag coating M but also the internal refractories such as dolomite and magnesia bricks will be cooled, so the internal bricks or the already coated layer will experience a spalling phenomenon. Otherwise, the slag coating layer peels off due to a difference in shrinkage between the adhesion surface of the coating layer and the brick. In order to suppress this flaking phenomenon, the slag coating is forcedly cooled by controlling the amount of gas or water when spraying, depending on the layer thickness of the slag coating.

This semi-solidified soft layer has excellent effects such as absorption of impact from the melting pot, slag, etc. and adhesion between the hardened coating layer of the slag coating layer, the existing slag coating layer, and the internal wall strength, and is also laminated. The deep soft layer naturally adheres due to warming and cooling, forming an integral fireproof wall.

〔Example〕

Next, an embodiment of the slag coating method according to the present invention will be described.

FIG. 1 is a cross-sectional view showing the concept of the slag coating of the present invention, and FIG. 2 is a cross-sectional view of the tip of a forced cooling lance.

First, refining is performed in a converter 3 in which a refractory lining 2 is installed on an iron shell 1, and the molten iron is tapped.
8 tons I7') Add 3 tons of dolomite as a modifier to the residual slag 4, and then blow Ar through the bottom blowing tuyere 5.
, blowing gas containing nitrogen or some oxidizing gas,
The residual slag 4 is scattered and a slag coating layer 6 is coated on the inner wall surface 7 of the converter. Next, liquid is sprayed onto the tip 8 of the cylindrical body made of, for example, a single tube or a double tube, by hanging a forced cooling lance 9 provided with a plurality of nozzles 10a to IOf into the converter 3 so as to be able to rise and fall freely. Then, for example, water is supplied as a liquid to the lance 9 by pressure feeding equipment such as a pump (not shown).
Water is supplied via The conditions for the lance 9 at this time are determined depending on the thickness of the coating layer. For example, lifting speed 1~
6 m/see, the water injection pressure is 5 to 8 kg/i, the water injection amount is tr160 to 30011/m, and it is dissipated as shown by the arrow. However, when using a gaseous fluid such as air nitrogen, a larger amount of water than the above water amount is used. It is necessary to supply cold gas of
Sufficient forced cooling cannot be achieved unless the lifting speed of the lance 9 is also slowed down.

The tip 8 of the lance 9 is directed toward the inner wall 7 of the converter 3, and the nozzles lOa to 10f are arranged alternately, or the lance 9 itself, which has a single hole or multiple nozzles, is raised and lowered. It may also rotate.

The coating layer was formed in this manner, and then one round of refining was performed. Thereafter, recoating and forced cooling were performed using the same method as above, and coating layers were laminated three times.

Table 1 shows the results of slag coating of a 170 ton converter compared with the conventional method.
In illegal methods, the life of the furnace is greatly extended despite the fact that the number of times of slag coating is clearly small, and furthermore, the downtime of the furnace body is reduced, and the consumption of slag modifiers, etc. is greatly reduced. It can be seen that this is an extremely excellent coating method.

Table-l Note) J: Coating and cooling 3 times for each charge, no coating for 5 charges.

忰2: Coating and cooling 5 times for each charge, no 5 charge coating.

〔Effect of the invention〕

As described above, by using the slag coating method of the present invention, a strong laminated slag coating layer is formed, which does not burn through during the next charging slag, stably protects the inner wall of the furnace, and Brick wear is prevented and the life of the furnace body is extended. In addition, the present invention is an excellent coating method that is extremely inexpensive and easy to perform by reducing the downtime of the furnace body associated with coating and eliminating the need for large consumption of slab modifiers and the like.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the concept of slag coating of the present invention, and FIG. 2 is a cross-sectional explanatory view of the tip of a forced cooling lance. 1... Iron shell, 2... Lining refractory, 3... Converter,
4... Residual slag or slag with modifier added, 5... Tuyere, 6. ...Slag coating layer, 7
... Inner wall surface of converter, 8... Tip of forced cooling lance, 9... Forced cooling lance, 10a-1Of... Nozzle for liquid spraying. Agent: Patent attorney Masamitsu Akizawa and 2 others

Claims (1)

[Claims] (1) After coating the inner wall surface of the converter with residual slag in the converter or slag to which a modifier has been added, the coating layer is forcibly cooled, and then after at least one charge of refining, the above-mentioned A slag coating method for a converter, characterized in that the coating layers are laminated by repeating coating.