JP3041981B2 - Tapping and slag method in smelting reduction furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smelting reduction method for producing molten iron by reducing ore containing iron oxides in a molten state, and efficiently uses molten slag and molten iron generated in a smelting reduction furnace. It relates to the method of discharging to the outside.

[0002]

2. Description of the Related Art In a converter (iron bath) type smelting reduction furnace, a method of continuously discharging the generated molten iron and molten slag has not been established at present. As a metallurgical reaction furnace similar to the converter type smelting reduction furnace, there are a steelmaking converter and a blast furnace, and the following methods can be considered as a method of discharging molten iron and slag out of the smelting furnace. A method in which smelting is interrupted once, as in a converter for steelmaking, and the furnace body is tilted and discharged from a tapping port attached to the furnace port or furnace shoulder. A method in which a hole is opened in the belly of the furnace like a blast furnace to discharge. However, in converter-type smelting reduction, the tapping and slag technology as described above cannot be applied from the viewpoint of continuous energy supply to the lower process as in the blast furnace, and from the viewpoint of improving productivity. is there. On the other hand, in a converter-type smelting reduction furnace, the molten iron and slag in the furnace are reduced by CO gas generated by the reduction reaction of iron oxide and an iron bath stirring gas blown from the furnace bottom for the purpose of promoting the reduction reaction and heat exchange. Since it contains a large amount of air bubbles, there are many problems in employing the tapping and slag method in a static bath such as a blast furnace.

[0003]

In the converter type smelting reduction, it is necessary to minimize the amount of carbon material used from the viewpoint of economy. Therefore, CO gas generated by the reduction reaction of iron oxide and H ₂ gas generated by using coal are
CO ₂ and H ₂ mainly from O ₂ supplied from above
Combustion to ₂ O ([H ₂ O +
CO ₂ ] / [CO + CO ₂ + H ₂ + H ₂ O]. It is an important technique to efficiently heat the heat generated to the metal bath to compensate for the heat absorption generated by the reduction reaction of iron oxide. It is effective to use molten slag as the heating medium, for that purpose, the heating zone is enlarged by forming the molten slag in the furnace, and the secondary combustion is performed in the slag bath. It is necessary to efficiently heat the combustion heat to the metal bath to prevent damage to the refractory. Therefore, it is required that the bulk density of the molten slag be as small as possible and stable. If the bulk density is 0.8 t / m ³ (the bulk density of the carbonaceous material) or less,
This the carbonaceous material in the molten slag is allowed to settle in the slag lower, O ₂ supplied from above is directly reacted with carbonaceous material in the slag, can be avoided O ₂ is used in the original secondary combustion decreases
Thus , the bulk density is one measure. At the same time, it is also important to transfer the heat applied to the molten slag to the metal bath, and to blow a stirring gas from the furnace bottom to promote the reduction reaction of iron oxide.

Therefore, the molten iron and molten slag in the smelting reduction furnace contain a large amount of bubbles during smelting,
This is a major factor in reducing the speed of discharging molten iron and slag to the outside of the furnace, and the discharge speed may not be able to keep up with the generation speed. At the same time, in order to maintain the heat transfer medium and prevent the blow-by of the bottom blow-off gas, it is necessary to always keep a certain amount or more of molten iron and molten slag in the furnace. In addition, iron ore charged with molten iron and slag,
In a furnace where the carbonaceous material and oxygen coexist, the molten slag may abnormally swell and overflow from the furnace port, causing a phenomenon that hinders continuous operation, so-called slopping. This phenomenon is due to T.C. in molten slag. It is known that it can be avoided by reduction of Fe and stable supply of carbonaceous material. Therefore, it is necessary to maintain a certain amount of excess carbonaceous material (hereinafter referred to as residual C) in the molten slag. Therefore, tapping
In the case of slag, it is required that these residual Cs are not discharged as much as possible.

Discharging the molten iron and slag generated by interrupting the smelting process to the outside of the furnace means that the smelting reduction method, which is an alternative to the blast furnace method, can continuously supply the surplus energy generated to the lower process. This means that it becomes impossible, and the energy balance of the entire steelworks may not be established. Thus, the tapping and slag method required for the converter (iron bath) type smelting reduction is that the smelting reduction process can be discharged without interruption, the discharge of residual C can be suppressed, and the remaining molten iron, It is possible to control the amount of molten slag.

[0006]

SUMMARY OF THE INVENTION In order to solve such problems, the present invention provides a converter (iron bath) -type smelting reduction furnace in a predetermined pressurized state, and opening of the furnace abdomen by tapping. carrying out the dregs, further, it is an its gist that increasing the bulk density of the molten slag during tapping, slag.

That is, the configuration of the present invention is as follows. (1) Ore containing iron oxide, carbon-containing material such as coal, medium solvent and oxygen are supplied into a converter-type vessel having molten iron and molten slag and into which the bottom-blown stirring gas is blown into the molten iron. In the tapping and slag method in the smelting reduction method for producing molten iron by ore melting and producing molten iron, at least at the time of tapping and slag, the atmospheric pressure in the vessel is set to 0.5 kg / cm ² G or more, and the abdomen of the vessel The molten slag and molten iron generated are discharged out of the vessel through the hole , and
・ Reduce the rate of molten iron generation during slag,
A tapping and slagging method in a smelting reduction furnace, wherein the rug has a bulk density of 0.8 t / m ³ or more . (2) In the above method (1), at least
At the time of slag, the atmospheric pressure in the container is set to 1.0 kg / cm ² G
The tapping and smelting in the smelting reduction furnace
Slag method. (3) In the above method (1) or (2), the bulk density of the molten slag in the container is set to 0.8 t / m by charging a slag forming inhibitor into the container during tapping and slagging.
A tapping / slagging method in a smelting reduction furnace, wherein the method is ³ or more.

[0008]

As described above, at least at the time of tapping and slagging, the inside of the container is kept at a pressure equal to or higher than a predetermined pressure, so that molten slag containing a large amount of air bubbles (hereinafter simply referred to as slag) and molten iron (Hereinafter, referred to as metal) can be efficiently discharged out of the vessel. In addition, by increasing the slag bulk density, slag discharge is further improved, and the residual C floats to the upper part of the slag. It is possible to allow the residual C to remain therein. Further, by opening a hole in the furnace abdomen, slag and metal below that level are not discharged, and the amount of remaining metal and slag can be controlled.

Hereinafter, the present invention will be described in detail. FIG. 1 shows the configuration of the equipment provided for implementing the present invention. In the figure,
1 is a smelting reduction furnace, 2 is an opener, 3 is a mud gun, 4
Is a tapping gutter, 5 is a lance, 6 is slag, and 7 is metal. In the present invention, the furnace abdomen of the smelting reduction furnace 1 is opened by the opener-2, and tapping and slag are performed from the opening. The opener-2 and the mud gun 3, which are tapping and slag facilities, may be those commonly used in blast furnaces.

FIG. 2 shows the relationship between furnace pressure and tapping / slag speed. According to this, slag and metal contain a large amount of air bubbles, so their discharge speed is low. However, the discharge speed is increased by increasing the furnace pressure, and the influence of the furnace pressure on this discharge speed is zero. It is remarkable in the range of 1.0 to 1.0 kg / cm ² G. From this, the furnace pressure was set to 0.5 kg /
It is understood that efficient tapping and slag can be achieved if the concentration is at least cm ² G, preferably at least 1.0 kg / cm ² G. For this reason, in the present invention, at least at the time of tapping and slag, the furnace pressure is 0.5 kg / cm ² G or more, preferably 1.0 kg / cm ² G or more.
cm ² G or more.

FIG. 3 shows the furnace pressure: 1.0 kg / cm ² G
2 shows the relationship between the slag bulk density and the slag speed at the time of (1). According to this, since the slag contains a larger amount of air bubbles than the metal, the slag speed is improved due to the increase in the bulk density, and the bulk density of the slag is reduced to 0 in order to perform efficient discharge. It turns out that it is necessary to set it to 0.8 t / m ³ or more.

As a method of increasing the bulk density of slag, it is effective to decrease the smelting speed. FIG. 4 shows the relationship between the smelting speed and the slag bulk density. According to this,
It turns out that the bulk density of slag can be increased by lowering the smelting speed. Further, the smelting speed can be reduced by an appropriate method, but by adding a forming inhibitor (such as a carbon material), the smelting speed is effectively reduced,
It is possible to increase the bulk density. FIG. 5 shows coal (TC; 73%, VM; 32) as a forming inhibitor.
%) Is shown at 10 kg / slag ton. According to this, by loading the forming inhibitor, it can be seen that the bulk density of the slag is increased to ^{0.5t / m 3 → 1.0t / m} 3.

By adopting the above method, the slag bulk density is reduced to 0.8 t / m ³ or less during smelting, and
The secondary combustion is effectively improved while the sediment is settled to the lower part of the slag, while the bulk density of the slag is 0.8 t during tapping and slagging.
/ M ³ or more, it is possible to improve the tapping speed, and as a result, efficient tapping and slag and continuous operation can be performed. Further, as shown in FIG. Can be suppressed to almost zero.

[0014]

7 and 8 show examples of operation according to the method of the present invention. The operating conditions at this time are as follows. Smelting speed: 3t-hot metal / h (1t-hot metal / m ^2- cross-sectional area in furnace / h), 0.6t-slag / h Furnace pressure: 1.8 kg / cm ² G Tapping and slag quantity: 4 0.5t-hot metal / tap, 1.0t-slag / tap forming inhibitor (coal [TC; 73%, VM; 3
1%]): 30 kg / tap (10 kg / t-slag) tap to tap: 1.5 h Opening equipment: Opener (tapping hole diameter: 0.045 m) Closing equipment: Mud gun In this embodiment, the pressure in the furnace is reduced. 1.8 kg / cm ²
G and the operation was performed with a slag bulk density of 0.5 t / m ³ , and the slag bulk density was 1.0 t / m ³ during tapping and slagging. As a result, as shown in FIG.
The tapping speed is 120 t / h, and the tapping speed is 3
6 t / h, which was much higher than the smelting speed, and it was possible to discharge metal and slag generated in the furnace with intermittent tapping and slag unlike a normal blast furnace. Also, the outflow of residual C during tapping and slag is almost eliminated. For this reason, the tapping and slag time can be significantly reduced, and the service life of the taphole refractory has been improved. As a result, the operation with a low slag bulk density can be performed for a long time, and the high secondary combustion operation can be continuously performed.

[0015]

As described above, according to the method of the present invention, the tapping / slag speed can be improved, and as a result,
The operation can be performed for a long time without impairing the productivity, and the outflow of the residual C is also eliminated, so that the carbon unit consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of equipment provided for carrying out the present invention.

FIG. 2 is a diagram showing the relationship between furnace pressure and tapping / slag speed.

FIG. 3 is a diagram showing the relationship between slag bulk density and slag speed.

FIG. 4 is a diagram showing a relationship between a smelting speed and a slag bulk density.

FIG. 5 is a view showing an effect of increasing a slag bulk density by charging a forming inhibitor.

FIG. 6 is a diagram showing the relationship between the bulk density of slag and the amount of residual C discharged during tapping and slagging.

FIG. 7 is a diagram showing an operation example of the present invention.

FIG. 8 is a diagram showing an operation example of the present invention.

Continuation of the front page (72) Inventor Jin Kawada 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (56) References JP-A-1-195230 (JP, A) JP-A-2-111807 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C21B 11/00-13/14

Claims (3)

(57) [Claims] An ore containing iron oxide and a carbon-containing material such as coal, a medium solvent and oxygen in a converter type vessel having molten iron and molten slag and into which a bottom-blown stirring gas is blown into the molten iron. Is supplied and molten ore is melt-reduced to produce molten iron. In the tapping and slag method in the smelting reduction method, at least at the time of tapping and slag, the atmospheric pressure in the vessel is set to 0.5 kg / cm ^2.
Together if not less than G, the abdominal vessels were opening, to discharge the generated molten slag and molten iron to the vessel out from the opening
In addition, the production rate of molten iron during tapping and slag is reduced,
The tapping / slagging method in a smelting reduction furnace, wherein the bulk density of the molten slag is 0.8 t / m ³ or more . 2. The method for tapping and slag in a smelting reduction furnace according to claim 1, wherein the atmosphere pressure in the vessel is at least 1.0 kg / cm ² G at least during tapping and slagging. To 3. A tapping-grounds vessel when Suragufo - claims the bulk density of the molten slag in the vessel by charging the timing inhibitor characterized by a 0.8 t / m ³ or more
Item 3. A tapping / slagging method in a smelting reduction furnace according to item 1 or 2 .