JP2022036648A - Pig iron melting apparatus and pig iron melting method - Google Patents

Abstract

To provide a pig iron melting apparatus capable of stably melting pig iron solidified in a torpedo car, and a melting method of pig iron using the pig iron melting apparatus thereof.SOLUTION: A pig iron melting apparatus 10 that melts a pig iron 5 solidified in a torpedo car 1 for carrying a hot metal includes: a heat insulating hood 11 arranged above a hot metal outlet of the torpedo car 1; exhaust gas suction means 13 arranged on the heat insulating hood 11; a direct-injection combustion burner 15 inserted into the torpedo car 1 through an insertion hole of the heat insulating hood 11; and lifting means 17 for raising and lowering the combustion burner 15, in which an oxygen-containing gas and a fuel are injected from a burner nozzle of the combustion burner 15, and flame generated by combustion collides with the pig iron 5 so that the pig iron 5 is locally heated and melt.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pig iron melting device for melting pig iron solidified in a torpedo car that carries hot metal, and a method for melting pig iron using this pig iron melting device.

A torpedo car (torpedo wagon) is used when transferring hot metal from a blast furnace to other equipment such as a converter.
Here, before transferring the hot metal to a converter or the like, out-of-converter refining such as slag removal, desiliconization, dephosphorization, and desulfurization may be performed in the torpedo car.
In these processing processes, if a long waiting time occurs due to the influence of operation adjustment or trouble, the hot metal temperature in the torpedo car drops to below the melting point of the hot metal, and the bullion adheres to the hot metal outlet. There was a risk that the hot metal could not be ejected and a large amount of hot metal in the torpedo car would solidify, resulting in a decrease in the hot metal utilization rate.

Therefore, various means have been conventionally proposed in order to prevent the hot metal from solidifying in the torpedo car.
For example, Patent Document 1 proposes a heat insulating lid for maintaining the temperature inside a torpedo car.
Further, Patent Document 2 proposes to preheat the inside of the torpedo car before receiving it from the blast furnace.
Further, Patent Document 3 proposes a method of melting pig iron solidified by a torpedo car by the heat of hot metal received from a blast furnace.

Jitsukaisho 56-034850 Japanese Unexamined Patent Publication No. 2012-082449 Japanese Unexamined Patent Publication No. 09-133469

By the way, in the heat insulating lid of Patent Document 1, the temperature inside the torpedo car can be maintained to some extent, but when a long time has passed, the hot metal in the torpedo car may be solidified. Moreover, it was not possible to dissolve the pig iron that had already solidified in the torpedo car.
Further, even when the inside of the torpedo car is preheated as in Patent Document 2, there is a possibility that the hot metal in the torpedo car will solidify after a long period of time. Moreover, it was not possible to dissolve the pig iron that had already solidified in the torpedo car.

In the method of melting pig iron by receiving pig iron from a blast furnace as in Patent Document 3, if a large amount of pig iron remains in the torpedo car, a sufficient amount of pig iron cannot be received from the blast furnace, and the pig iron cannot be received. Could not be dissolved. In addition, the received hot metal solidifies, and conversely, there is a risk that the pig iron inside the torpedo car will increase. Furthermore, if the entire pig iron in the torpedo car melts at once, the weight balance in the torpedo car will be lost, and there is a risk that the upper limit of the tilting motor load will be exceeded or the torpedo car will tip over when tilting, and the torpedo car cannot be tilted stably. There was a risk that the hot metal could not be discharged. In addition, the molten slag generated during melting may come into contact with the refractory material, resulting in deterioration of the refractory material.

The present invention has been made in view of the above-mentioned situation, and is a pig iron melting device capable of stably melting pig iron solidified in a torpedo car, and a method for melting pig iron using this pig iron melting device. The purpose is to provide.

In order to solve the above problems, the pig iron melting device according to the present invention is a pig iron melting device that melts pig iron solidified in a torpedo car that carries hot metal, and is arranged above the iron outlet of the torpedo car. A heat insulating hood, an exhaust gas suction means arranged in the heat insulating hood, a direct injection type combustion burner inserted into the torpedo car through the insertion hole of the heat insulating hood, and an elevating means for raising and lowering the combustion burner. It is characterized in that oxygen-containing gas and fuel are injected from the burner nozzle of the combustion burner, the flame generated by the combustion is made to collide with the pig iron, and the pig iron is locally heated and melted.

According to the pig iron melting device having this configuration, oxygen-containing gas and fuel are injected from the burner nozzle of the direct-injection type combustion burner, and the flame generated by the combustion collides with the pig iron. It can be locally heated and melted into a mortar shape. Therefore, pig iron can be melted without disturbing the weight balance. Therefore, it is possible to stably discharge the molten pig iron (hot metal) by tilting the torpedo car. Further, by locally heating the pig iron and melting it in the shape of a mortar, it is possible to suppress the molten slag from coming into contact with the refractory material, and it is possible to suppress the deterioration of the refractory material.

Further, since the heat insulating hood provided with the exhaust gas suction means is provided, the exhaust gas generated by the combustion can be discharged to the outside by the exhaust gas suction means, and the flame state of the direct injection type combustion burner can be stabilized.
Further, since the direct-injection type combustion burner can be raised and lowered, the flame of the direct-injection type combustion burner can be surely collided with the pig iron, and the pig iron can be locally heated and melted.

The method for melting pig iron according to the present invention is a method for melting pig iron solidified in a torpedo car that transports hot metal, and is an oxygen-containing gas from a burner nozzle of the combustion burner using the above-mentioned pig iron melting device. It is characterized by injecting fuel and causing the flame generated by combustion to collide with the pig iron to locally heat the surface of the pig iron to a temperature at which it can be melted.

According to the method for melting pig iron having this configuration, oxygen-containing gas and fuel are injected from the burner nozzle of a direct-injection type combustion burner, and the flame generated by the combustion collides with the pig iron, so that the pig iron solidified in the torpedo car. Can be locally heated and melted into a mortar shape. Therefore, pig iron can be melted without disturbing the weight balance. Therefore, it is possible to stably discharge the molten pig iron (hot metal) by tilting the torpedo car. Further, by locally heating the pig iron and melting it in the shape of a mortar, it is possible to suppress the molten slag from coming into contact with the refractory material, and it is possible to suppress the deterioration of the refractory material.

Here, in the method for melting pig iron according to the present invention, it is preferable that the oxygen ratio in the oxygen-containing gas and fuel injected from the combustion burner is in the range of 1.3 or more and 1.8 or less.
Here, the oxygen ratio is, in the present invention, the oxygen volume flow rate / the theoretical oxygen amount (the volume flow rate of oxygen required for complete combustion of the fuel) in the gas injected from the burner in which oxygen and the fuel are mixed. The oxygen ratio obtained from the formula of.
By setting the oxygen ratio to 1.3 or more, the generation of unburned gas and soot can be suppressed, and contamination in the burner nozzle and the torpedo car can be prevented. In addition, the oxygen reaction of carbon in the hot metal can be promoted, and the heat of this reaction makes it possible to efficiently dissolve pig iron.
On the other hand, by setting the oxygen ratio to 1.8 or less, decarburization due to oxidation on the surface of pig iron can be suppressed and the melting point of pig iron can be prevented from becoming high. In addition, it is possible to suppress the generation of a large amount of slag, and it is possible to suppress the deterioration of the refractory.

Further, in the method for melting pig iron according to the present invention, the flame length Lb (m) of the combustion burner, the distance H (m) from the pig iron outlet to the pig iron surface, and the insertion depth Ld (m) of the burner nozzle. When the linear distance D (m) from the primary flame collision point on the pig iron surface to the inner wall surface of the torpedo car and the burner nozzle diameter Db (m) are set.
0 <(Lb- (H-Ld)) / Db <D / Db
It is preferable to adjust the oxygen-containing gas supply amount, the fuel supply amount, and the height position of the nozzle of the burner so as to satisfy the above.
In this case, since the oxygen-containing gas supply amount, the fuel supply amount, and the height position of the burner nozzle are adjusted so that the flame length is within the above range, the flame is applied to the inner wall surface of the torpedo car. Collision can be suppressed, and deterioration of refractories can be further suppressed.

Further, in the method for melting pig iron according to the present invention, the metal adhering to the pig iron outlet may be removed by heating with the combustion burner.
In this case, the bullion attached to the pig iron is locally heated to melt the bullion, the bullion is fumed by high-temperature oxidative decomposition by the combustion exhaust gas, or the bullion is softened and dropped into the torpedo car. It is possible to efficiently remove the bare metal adhering to the hot metal outlet, and it is possible to stably discharge the melted pig iron (hot metal) from the hot metal outlet to the outside.

Further, in the method for melting pig iron according to the present invention, coke oven gas, propane or heavy oil may be used as the fuel.
In this case, since coke oven gas, propane, or heavy oil is used as the fuel, the combustion of the combustion burner can surely generate a flame, and the pig iron in the torpedo car can be locally heated and melted.

As described above, according to the present invention, it is possible to provide a pig iron melting device capable of stably melting pig iron solidified in a torpedo car, and a method for melting pig iron using this pig iron melting device. ..

It is a schematic explanatory drawing of the pig iron melting apparatus which is one Embodiment of this invention. (A) is a vertical cross-sectional explanatory view of the torpedo car, and (b) is a cross-sectional explanatory view of the torpedo car. It is a graph which shows the result of Example 1. FIG. It is an observation photograph which shows the result of Example 2. (A) is the state of the bullion before heating, and (b) is the state of the bullion after heating.

Hereinafter, a pig iron melting device according to an embodiment of the present invention and a method for melting pig iron using this pig iron melting device will be described. The present invention is not limited to the following embodiments.
The pig iron melting device of the present embodiment melts the pig iron solidified in the torpedo car. In particular, it is used in a situation where a large amount of solidified pig iron is present in the torpedo car and the hot metal cannot be received from the blast furnace.

As shown in FIG. 1, the pig iron melting device 10 according to the present embodiment includes a heat insulating hood 11 arranged above the hot metal outlet of the torpedo car 1, an exhaust gas suction means 13 provided in the heat insulating hood 11. It has a direct-injection type combustion burner 15 inserted into the torpedo car 1 through an insertion hole (not shown) of the heat insulating hood 11 and an elevating means 17 for raising and lowering the combustion burner 15.
The combustion burner 15 has a structure in which oxygen-containing gas and fuel are injected from a burner nozzle to generate a flame by combustion. At this time, the exhaust gas generated by the combustion of the combustion burner 15 is discharged to the outside by the exhaust gas suction means 13.
Here, as the fuel, for example, coke oven gas, propane or heavy oil can be used. Further, as the oxygen-containing gas, oxygen gas, air or the like can be used.

In the pig iron melting device 10 of the present embodiment, the direct injection type combustion burner 15 is inserted into the torpedo car 1, oxygen-containing gas and fuel are injected from the burner nozzle of the combustion burner 15, and the flame generated by the combustion is emitted to the pig iron 5. Collide with. As a result, the pig iron 5 is locally heated to melt a part of the pig iron 5.

Here, in the present embodiment, it is preferable that the oxygen ratio in the oxygen-containing gas and the fuel injected from the combustion burner 15 is in the range of 1.3 or more and 1.8 or less.
By setting the oxygen ratio to 1.3 or more, the fuel can be reliably burned, and the generation of unburned gas and soot can be suppressed. Further, the oxidation reaction of carbon in the hot metal can be promoted, and the heat of this reaction can promote the dissolution of the pig iron 5. On the other hand, by setting the oxygen ratio to 1.8 or less, it is possible to suppress the generation of a large amount of slag, and it is possible to suppress the deterioration of the refractory and the occurrence of slag forming.
The lower limit of the oxygen ratio is more preferably 1.3 or more, and further preferably 1.4 or more. Further, the upper limit of the oxygen ratio is more preferably 1.7 or less, and further preferably 1.6 or less.

Further, in the present embodiment, the flame length Lb (m) of the combustion burner 15, the distance H (m) from the hot metal outlet to the surface of the pig iron 5, the insertion depth Ld (m) of the burner nozzle, and the pig iron 5 When the linear distance D (m) from the primary flame collision point on the surface to the inner wall surface of the torpedo car 1 and the burner nozzle diameter Db (m) are set.
0 <(Lb- (H-Ld)) / Db <D / Db
It is preferable to adjust the oxygen-containing gas supply amount, the fuel supply amount, and the height position of the burner nozzle so as to satisfy the above.
By adjusting the flame length as described above, it is possible to prevent the flame from colliding with the inner wall surface of the torpedo car 1.

Here, the flame length can be controlled by the combustion calorific value based on the following design formula.

In the above-mentioned pig iron melting device 10, as described above, oxygen-containing gas and fuel are injected from the burner nozzle of the combustion burner 15, the flame generated by the combustion is made to collide with the pig iron 5, and the pig iron 5 is locally heated. , A part of pig iron 5 is melted.
Then, the hot metal generated by melting a part of the pig iron 5 is discharged to the outside from the hot metal outlet by tilting the torpedo car 1.
After that, the torpedo car 1 is returned to the original position, the direct injection type combustion burner 15 is reinserted into the torpedo car 1, and the pig iron 5 is locally heated again to melt a part of the pig iron 5.
By repeating this work, the pig iron 5 solidified in the torpedo car 1 can be melted to secure a space in the torpedo car 1, and the pig iron can be received from the blast furnace.

Further, in the present embodiment, it is possible to remove the bare metal adhering to the ironing port by the combustion heat of the combustion burner 15.
The height position of the combustion burner 15 may be adjusted to cause the flame to collide with the metal adhering to the ironing port to melt it. Further, the bare metal may be oxidatively decomposed at high temperature by the combustion exhaust gas of the combustion burner 15 to form a fume. Further, the bare metal may be softened by the heat rise and dropped into the torpedo car 1.

According to the pig iron melting device and the pig iron melting method of the present embodiment having the above configuration, the direct injection type combustion burner 15 is inserted into the torpedo car 1, and the oxygen-containing gas is inserted from the burner nozzle of the combustion burner 15. And fuel is injected, and the flame generated by combustion collides with the pig iron 5 in the torpedo car 1, so it is possible to locally heat the pig iron 5 solidified in the torpedo car 1 and melt it into a mortar shape. Become. Therefore, the pig iron 5 can be melted without disturbing the weight balance. Therefore, the torpedo car 1 can be tilted to stably discharge the melted pig iron (hot metal). Further, by locally heating the pig iron 5 and melting it in a mortar shape, it is possible to suppress the molten slag from coming into contact with the refractory material, and it is possible to suppress the deterioration of the refractory material.

Further, since the heat insulating hood 11 provided with the exhaust gas suction means 13 is arranged above the metal outlet, the exhaust gas generated by the combustion can be discharged to the outside by the exhaust gas suction means 13, and the direct injection type combustion burner 15 can be used. The state of the flame can be stabilized.
Further, since the elevating means 17 for raising and lowering the direct injection type combustion burner 15 is provided, the flame of the combustion burner 15 can be surely collided with the pig iron 5.

Further, in the present embodiment, when the oxygen ratio in the oxygen-containing gas and the fuel ejected from the combustion burner 15 is 1.3 or more, the generation of unburned gas and soot can be suppressed, and the inside of the burner nozzle and the torpedo car 1 can be suppressed. It is possible to prevent the contamination of pig iron and promote the oxygen reaction of carbon in the hot metal, and the heat of this reaction makes it possible to efficiently melt the pig iron 5.
On the other hand, when the oxygen ratio is set to 1.8 or less, decarburization due to oxidation on the surface of pig iron 5 can be suppressed, the melting point of pig iron 5 can be prevented from increasing, and a large amount of slag can be suppressed. Deterioration of refractory can be suppressed.

Further, in the present embodiment, the flame length Lb (m) of the combustion burner 15, the distance H (m) from the hot metal outlet to the surface of the pig iron 5, the insertion depth Ld (m) of the burner nozzle, and the surface of the pig iron 5 When the linear distance D (m) from the primary collision point of the flame to the inner wall surface of the torpedo car 1 and the burner nozzle diameter Db (m) are set in
0 <(Lb- (H-Ld)) / Db <D / Db
When the oxygen-containing gas supply amount, the fuel supply amount, and the height position of the burner nozzle of the combustion burner 15 are adjusted so as to satisfy the above, it is possible to prevent the flame from colliding with the inner wall surface of the torpedo car 1. , It is possible to further suppress the deterioration of the refractory material.

Further, in the present embodiment, when the configuration is such that the bullion adhering to the ironing port is removed by heating by the combustion burner 15, the bullion adhering to the ironing port can be efficiently removed. It is possible to efficiently and stably carry out the discharge work of molten pig iron (hot metal) and the receiving work from the blast furnace.

Further, in the present embodiment, when coke oven gas, propane or heavy oil is used as the fuel, the combustion of the combustion burner 15 surely generates a flame and locally heats the pig iron 5 in the torpedo car 1. It becomes possible to dissolve it.

Although the pig iron melting apparatus and the method for melting pig iron, which are the embodiments of the present invention, have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the present invention. Is.

(Example 1)
In order to confirm the effect of the pig iron melting device and the pig iron melting method of the present invention, the pig iron in the torpedo car was melted under various conditions. The results are shown in Table 1 and FIG. Here, the melting conditions and melting conditions of pig iron are described using the following indexes.
Receiving index = Receiving amount / Maximum receiving capacity (380t)
Dissolution index = (weight after dissolution-weight before dissolution) / (weight after dissolution under condition 1-weight before dissolution) × -1
In Condition 1, the weight after dissolution is larger than the weight before dissolution (the amount of pig iron is increasing), so the dissolution index is expressed by multiplying by -1.

Here, the amount of dissolution is measured before and after the hot metal in the torpedo car is discharged from the hot metal outlet to the hot metal pan while the torpedo car is tilted, and the weighing machine mounted on the hot pot cart is used. The difference was measured and this payout amount was taken as the dissolution amount.
The absolute value of the amount of dissolution by the receiving iron was obtained by subtracting the amount of receiving iron from the blast furnace from the amount of payout measured by the weighing machine of the receiving pig iron, and using this as the amount of dissolving by the receiving iron. For the amount of pig iron received in the blast furnace, the height of the pig iron before and after the receiving iron was measured with a molten metal level meter, and the pig iron weight in the torpedo car was calculated from this value.

Condition 1 is that the pig iron is melted only by receiving the pig iron from the blast furnace. There was no space to receive the hot metal in the torpedo car, and the hot metal receiving index was as low as 0.08. Then, the received hot metal solidified, and the melting index became -1.00.

Condition 2 was that the heat was raised for 24 hours using a combustion burner, but the flame length was short and the flame did not directly collide with the pig iron. The dissolution index was 0.01, and pig iron could hardly be dissolved.

Condition 3 is that the heat is raised for 12 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 1.18, which was D / Db (4.22) or less, and the oxygen ratio was 1.9 before dissolution and 1.7 after dissolution. The dissolution index was 0.14, and more pig iron could be dissolved than in Condition 2.

Condition 4 is that the heat is raised for 12 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 2.00 and was D / Db (4.03) or less, and the oxygen ratio was 2.0 before dissolution and 2.0 after dissolution. As a result, the dissolution index was 0.04, and a small amount of pig iron could be dissolved.

Condition 5 is that the heat is raised for 12 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 2.89 and D / Db (3.82) or less, and the oxygen ratio was 1.4 before dissolution and 2.1 after dissolution. The dissolution index was 0.25, and a relatively large amount of pig iron could be dissolved. The oxygen ratio after dissolution was relatively high, slag was generated, and refractory erosion was observed.

Condition 6 is that the heat is raised for 12 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 0.80 and D / Db (4.03) or less, and the oxygen ratio was 1.2 before dissolution and 1.2 after dissolution. The dissolution index was 0.19, and a relatively large amount of pig iron could be dissolved. Since the oxygen ratio was relatively low, soot was generated.

Condition 7 is that the heat is raised for 12 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 1.69, which was D / Db (3.82) or less, and the oxygen ratio was 1.5 before dissolution and 1.5 after dissolution. The dissolution index was 0.19, and a relatively large amount of pig iron could be dissolved.

Condition 8 is that the heat is raised for 24 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 0.88, which was D / Db (4.40) or less, and the oxygen ratio was 1.7 before dissolution and 1.7 after dissolution. The dissolution index was 0.19, and a relatively large amount of pig iron could be dissolved.

Condition 9 is that the heat is raised for 48 hours using the pig iron melting device of the present invention. In addition, (Lb- (H-Ld)) / Db was 0.88, which was D / Db (4.40) or less, and the oxygen ratio was 1.7 before dissolution and 1.7 after dissolution. The dissolution index was 0.54, and a large amount of pig iron could be dissolved.

Condition 10 is a state in which the inside of the torpedo car is preheated by a preheating burner, and the pig iron is melted by receiving the pig iron from the blast furnace. The pig iron index was as low as 0.13. Then, a part of the hot metal received was solidified, and the dissolution index became −0.18.

(Example 2)
Using the pig iron melting device of the present invention, the temperature was raised for 9.5 hours to remove the bullion at the hot metal outlet. FIG. 3 shows observation photographs of the ironing port before and after the temperature rise. After the temperature was raised, it was confirmed that the bullion decreased and the opening area of the ironing port increased.

From the above results, according to the present invention, it is possible to provide a pig iron melting device capable of stably melting pig iron solidified in a torpedo car, and a method for melting pig iron using this pig iron melting device. Was confirmed.

1 Torpedo car 5 Pig iron 10 Pig iron melting device 11 Heat insulation hood 13 Exhaust gas suction means 15 Combustion burner 17 Lifting means

Claims (6)

A pig iron melting device that melts pig iron solidified in a torpedo car that transports hot metal.
A direct injection type combustion inserted into the torpedo car through a heat insulating hood arranged above the ironing port of the torpedo car, an exhaust gas suction means arranged in the heat insulating hood, and an insertion hole of the heat insulating hood. It has a burner and a means for raising and lowering the combustion burner.
A pig iron melting device characterized in that oxygen-containing gas and fuel are injected from a burner nozzle of the combustion burner, a flame generated by combustion is made to collide with the pig iron, and the pig iron is locally heated and melted. It is a method of melting pig iron that melts pig iron solidified in a torpedo car that transports hot metal.
Using the pig iron melting device according to claim 1, oxygen-containing gas and fuel can be injected from the burner nozzle of the combustion burner, and the flame generated by the combustion can be made to collide with the pig iron to melt the surface of the pig iron. A method for melting pig iron, which comprises locally heating to a temperature. The method for melting pig iron according to claim 2, wherein the oxygen ratio in the oxygen-containing gas and the fuel injected from the combustion burner is in the range of 1.3 or more and 1.8 or less. The flame length Lb (m) of the combustion burner, the distance H (m) from the pig iron surface to the pig iron surface, the insertion depth Ld (m) of the burner nozzle, and the flame primary collision point on the pig iron surface of the torpedo car. When the straight distance to the inner wall surface is D (m) and the burner nozzle diameter is Db (m),
The pig iron according to claim 2 or 3, wherein the oxygen-containing gas supply amount, the fuel supply amount, and the height position of the nozzle of the burner are adjusted so as to satisfy the following formula. Dissolution method.
0 <(Lb- (H-Ld)) / Db <D / Db The method for melting pig iron according to any one of claims 2 to 4, wherein the bullion adhering to the iron outlet is removed by heating with the combustion burner. The method for melting pig iron according to any one of claims 1 to 5, wherein coke oven gas, propane or heavy oil is used as the fuel.

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