JP4440202B2 - How to put cold iron into hot metal ladle - Google Patents

Description

  The present invention relates to a method for charging a cold iron source into an empty hot metal ladle among methods for producing molten steel using a converter.

  Conventionally, the kneading wheel or hot metal ladle that has completed the discharge of the hot metal to the converter is returned to the conveyance source in preparation for the next receiving. At this time, the kneading wheel or the hot metal ladle releases the heat obtained by the hot metal before the discharge into the atmosphere, and heat loss occurs here. The heat loss causes a decrease in the temperature of the hot metal that will be subsequently charged into the kneading wheel or hot metal ladle, thereby reducing the amount of cold iron source added to the hot metal blown in the converter process. As a result, the increase in production of crude steel will be reduced. In order to solve this problem, an operation method for reducing heat loss has been proposed.

For example, Patent Literature 1 to Patent Literature 3 disclose an operation method for reducing heat loss of a chaotic vehicle. In these operating methods, a cold iron source is placed in the furnace body of a kneading car that is returned from the converter to the blast furnace, and heat radiation is absorbed by the cold iron source to suppress heat loss. In addition, since the opportunity for charging the cold iron source into the hot metal before blowing is increased, the hot metal mixture ratio (HMR) of the entire operation can be reduced.
JP 54-142116 A Japanese Patent No. 2652296 JP-A-5-59421

In the above-mentioned Patent Documents 1 to 3, the weight of the cold iron source is defined to be about 10% of the weight of the received iron for the purpose of dissolving all of the previously placed cold iron source by receiving from the blast furnace. ing.
However, if a cold iron source of such weight is placed in the hot metal ladle, as a result of the field, prescribing the weight of the cold iron source to be placed only from the receiving weight is too much of the cold iron source However, depending on the storage of such an excessive cold iron source, the effect of reducing the heat loss of the cold iron source cannot be fully exhibited, and the operation is adversely affected. .

  Accordingly, the present invention provides a hot metal ladle that can effectively exert the heat loss reduction effect of the cold iron source by appropriately setting the weight of the cold iron source to be placed in the hot metal ladle while preventing adverse effects on the operation. The purpose is to provide a method for supplying cold iron to the house.

In order to achieve the above object, the present invention takes the following technical means.
That is, the first technical means for solving the problems in the present invention is:
Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The weight of the cold iron source placed in the empty hot metal ladle is set so as to satisfy the expressions (1) and (2).

It is known that the heat loss in the hot metal ladle is mainly due to external heat radiation from the hot metal ladle surface and heat radiation from the pan mouth.
In the cold iron source charging method to the hot metal ladle according to the present invention, the cold iron source is put in the hot metal ladle, and the cold iron source absorbs the heat that is originally released by external heat radiation, thereby It suppresses the release of heat in the hot metal ladle to the outside. Here, the amount of heat released by the external heat dissipation varies depending on the size of the area of the pan mouth of the hot metal pan, for example, the heat dissipation from the pan mouth increases as the area of the pan mouth of the hot metal pan increases, The amount of heat in the hot metal ladle becomes relatively small, and accordingly, the amount of heat released by the external heat dissipation becomes small. The inventors of the present application paid attention to this point and repeated experiments on the area of the pan mouth and the weight of the cold iron source placed in the hot metal pan. As a result, if the weight of the cold iron source to be kept is within the range of the following formula (1A), the dissipated heat due to external heat dissipation is sufficiently absorbed by the cold iron source, and consequently the heat loss of the cold iron source It was discovered that the reduction effect was fully demonstrated.

Also, the stored cold iron source is preheated by receiving radiant heat from the inner wall of the hot metal ladle, and when the temperature of the inner wall surface and the surface of the cold iron source become equal, the air in the cold iron source and hot metal pan is heated. The heat transfer between is in equilibrium. For this reason, the heat insulation state is maintained in the hot metal ladle by the preheated cold iron source, and this also reduces the heat loss of the hot metal ladle.
On the other hand, in order to suppress heat dissipation through the pan mouth, the inner wall surface of the hot metal pan, in particular, the bottom of the pan is covered by a cold iron source, and the radiant heat released from the pan bottom through the pan mouth to the hot metal pan is reduced. It is effective to suppress. As a result, the surface temperature of the pan bottom is lowered, and the release of radiant heat from the pan bottom as shown by the Stefan-Boltzmann law is suppressed.

  Generally, the cold iron source to be placed is put into the hot metal ladle by known means and deposited on the pan bottom. As a result of repeated experiments on the weight of the cold iron source to be placed, even when the cold iron source is put into the hot metal ladle by known means by setting the weight of the cold iron source within the range of the following formula (1B) We have discovered that it is possible to cover the pan bottom with a cold iron source.

Therefore, when prescribing the weight of the cold iron source to be kept for the purpose of reducing the heat loss of the hot metal ladle, by setting the weight of the cold iron source within the range satisfying the formula (1), Therefore, the heat loss reduction effect of the cold iron source can be sufficiently exerted against the heat radiation.
Further, if the cold iron source is excessively placed in the hot metal received by the hot metal ladle, the cold iron source remains undissolved and the temperature drop of the hot metal becomes remarkable. Thereby, there is a possibility that the metal will adhere to the inner wall of the hot metal ladle and the remarkable temperature drop of the hot metal may hinder the subsequent operation.

Therefore, the inventor of the present application examined in detail the operation results regarding the weight of the cold iron source to be placed and the weight of the hot metal to be received. As a result, by setting the weight of the cold iron source to be put in the range of the above formula (2), it is possible to dissolve all of the cold iron source and to prevent a significant temperature drop of the hot metal received. Know that you can.
Therefore, by making the weight of the cold iron source to be placed satisfy the above formulas (1) and (2), the effect of reducing the heat loss of the cold iron source to be left can be sufficiently exhibited, and The operation after putting the source in place can be improved.

The second technical means for solving the problems in the present invention is:
Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The hot metal is dephosphorized before the received hot metal is discharged into the receiving container, and the cold iron source is placed in the empty hot metal pan. The weight is set so as to satisfy the expressions (1) and (3).

In the above operating method, the hot metal received in the hot metal ladle is subjected to a dephosphorization process and then discharged to the converter.
In the dephosphorization treatment, generally, a gas acid (oxygen gas) and a solid acid (such as iron oxide) are simultaneously charged into the hot metal as a dephosphorization material. At this time, it is desirable to perform the treatment with a high-efficiency solid acid ratio larger than a low-efficiency gas acid ratio. However, the dephosphorization treatment with a solid acid includes an endothermic reaction, and an increase in the solid acid ratio leads to a large consumption of the amount of heat in the hot metal, which causes a significant decrease in the temperature of the hot metal.

In order to prevent such a temperature drop, it is desirable that the hot metal has a sufficient heat margin before the dephosphorization treatment. Therefore, the inventor of the present application sets the weight of the cold iron source placed in the hot metal ladle to the above formula (3) or less, so that the amount of heat of the hot metal is slightly deprived by the cold iron source. It has been found that the heat margin of the hot metal for performing the dephosphorization treatment can be sufficiently maintained.
And by making the weight of the cold iron source to put into below Formula (3), the solid acid ratio of a dephosphorization process can be increased, and also the ratio of the low-efficiency gaseous acid can be reduced. is there.

The dephosphorization process may be performed before the hot metal charged in the hot metal ladle is discharged to the converter. Therefore, the period until the received hot metal is discharged to the receiving container can be expanded to include the period after the hot metal is discharged to the receiving container thereafter. Regardless of the time, by defining the weight of the cold iron source according to the above equation (3), the temperature drop of the hot metal due to the dephosphorization treatment of the hot metal is taken into consideration.
The third technical means for solving the problems in the present invention is:
Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. And the weight of the cold iron source placed in the empty hot metal ladle is set so as to satisfy the equations (4) and (2).

  According to the above operation method, the hot metal ladle is in an empty state from the completion of the hot metal discharge until the start of placing the cold iron source, and at this time, the heat in the hot metal ladle is released as heat loss to the atmosphere. . Therefore, the inventor of the present application pays attention to the heat loss due to heat radiation from the completion of hot metal discharge to the start of putting in the cold iron source, and the time from the completion of hot metal discharge to the start of putting in the cold iron source in the above formula (1A). By introducing it as a variable, it is known that the following formula (4A) is obtained in consideration of heat radiation from the hot metal ladle before the cold iron source is charged.

  Further, the above formula (1B) is further examined, and it is found that the average bulk specific gravity of the cold iron source affects the weight of the cold iron source for the purpose of covering the bottom of the pan with the cold iron source to be placed. did. From this viewpoint, by introducing the bulk specific gravity of the cold iron source as a variable into the above formula (1B), the following formula (4B) considering the properties of the cold iron source to be input is obtained.

Thus, in the above equation (4), when reducing the heat loss of the hot metal ladle by placing the cold iron source, the time from the completion of the hot metal discharge to the start of placing the cold iron source and the average bulk of the cold iron source In consideration of the relationship with the specific gravity, the weight of the cold iron source to be placed will be defined as more realistic.
Furthermore, in view of this point, as a fourth technical means for solving the problems in the present invention,
Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The hot metal is dephosphorized before the received hot metal is discharged into the receiving container, and the cold iron source is placed in the empty hot metal pan. It is preferable that the weight is set so as to satisfy the expressions (4) and (3).

  According to the cold iron source charging method to the hot metal ladle according to the present invention, the heat loss reduction effect by the cold iron source is set with an appropriate weight of the cold iron source placed in the hot metal ladle while preventing adverse effects on the operation. Can be exhibited effectively.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
In the flow of the steelmaking process of the present embodiment, as shown in FIG. 1, the hot metal made in the blast furnace 1 is received by the hot metal ladle 2 and conveyed to the converter facility 3 by the hot metal ladle 2. Here, the hot metal is subjected to a desiliconization process on the casting floor and is subjected to a demetalization process during conveyance by the hot metal ladle 2, and then is discharged to the converter (receiving vessel) 4 of the converter facility 3. . In the present embodiment, a dephosphorization converter (converter type dephosphorization furnace or de-P furnace) 4A and a decarburization converter (converter type decarburization furnace or deC furnace) 4B are employed as the converter 4. Thus, the hot metal in the hot metal ladle 2 is discharged to the dephosphorization converter 4A.

The hot metal in the hot metal ladle may be dispensed from the hot metal ladle 2 to another receiving container such as a hot metal ladle for a dephosphorization furnace.
The hot metal discharged to the dephosphorizing converter 4A is subjected to a dephosphorizing process in the dephosphorizing converter 4A, and then temporarily discharged to the converter charging hot metal ladle 6. The hot metal conveyed before the decarburization furnace 4B by the converter charging hot metal ladle 6 is discharged from the converter charging hot metal ladle 6 to the decarburization converter 4B, and carbon is transferred to the decarburization converter 4B. The amount is adjusted to become molten steel. Then, the molten steel is discharged from the decarburizing converter 4B to the molten steel pan 7, and then commercialized through a molten steel process (secondary refining process) and a continuous casting process.

In the flow, as described above, the hot metal ladle 2 reciprocates between the blast furnace 1 and the dephosphorization converter 4A of the converter facility 3 to convey the hot metal, and the dephosphorization process and the decarburization process convert the hot metal into the respective hot metal. It carries out in the state inserted into the furnace 4A, 4B, and the molten steel pan 7 conveys molten steel toward the downstream continuous casting process from the converter equipment 3. FIG.
Here, as shown in FIG. 2, the hot metal ladle 2 of the present embodiment is formed in a bottomed straight cylinder shape having a pan bottom 11 and a pan mouth 12 having the same or slightly larger area as the pan bottom 11. In this embodiment, it is transported to the converter facility by a transport cart (not shown) and then lifted to the pan transport crane 13.

In addition, the hot metal ladle 2 has an outer layer formed of an iron skin 14, and a refractory material (refractory brick) 15 made of clay or high alumina containing an organic substance as a binder is pasted without a gap. ing.
In the flow of the present embodiment shown in FIG. 1, a hot metal ladle 2, a converter charging hot metal pan 6, and a molten steel pan 7 are used as a transport container (a receiving container) for transporting hot metal and molten steel by moving between the processing facilities. Etc. are adopted. These transport containers receive heat from the hot metal or molten steel that is received and become high temperature. However, the heat is released into the atmosphere before the transport container is returned from the transport destination to the transport source, and is heated here. Loss occurs.

In particular, in the hot metal ladle 2, after the hot metal is discharged to the dephosphorization converter 4A by the converter equipment 3, it is returned to the casting bed (not shown) of the blast furnace 1, but heat loss occurs during the return. ing.
In the present embodiment, a cold iron source charging facility 9 is arranged on the return line of the hot metal ladle 2, and the cold iron source C is placed in the hot metal ladle 2 that has been emptied by charging the hot metal into the dephosphorization converter 4A. It is supposed to be left in place, thereby reducing heat loss when the hot metal ladle 2 is returned.
In the present embodiment, the cold iron is used as the cold iron source C.
By the way, it is known that the heat loss of the hot metal ladle 2 is mainly due to heat radiation from the iron skin 14 and the release of heat in the pan from the pan mouth 12. Here, the present inventors have found that the release of heat in these two paths is effectively suppressed by defining the weight of the cold iron source C to be placed.

  First, for the heat radiation from the iron skin 14, the heat in the pan is absorbed by the cold iron source C, and the heat radiation is suppressed by the preheating effect of the cold iron source C. That is, the heat in the pan to be released from the iron skin 14 is absorbed by the cold iron source C to be put in, and the cold iron source C is preheated by the heat. And the heat radiation (radiant heat) from the preheated cold iron source C is received by the inner wall of the hot metal ladle 2. Thereby, it forms in a thermal equilibrium state between the cold iron source C and the inner wall in the pan, and the heat insulation state in the pan is maintained. As a result, the inner wall temperature of the hot metal pan 2 is lowered, and heat transfer The temperature of the iron skin 14 also decreases. As a result, the amount of heat released from the iron skin 14 is reduced.

At this time, since the heat radiation amount in the pot from the pot opening 12 increases as the area of the pot opening 12 increases, the amount of heat in the pot becomes small. That is, the amount of heat in the hot metal ladle 2 depends on the area of the hot pot 12, and accordingly, the weight of the cold iron source C to be placed also varies depending on the area of the hot pot 12.
The inventors of the present application have found that the weight of the cold iron source C to be placed varies linearly with respect to the area of the pan opening 12. In addition, when the area A of the pot mouth 12 is 7.1 m ² , even if a cold iron source C of 10.6 ton or more is left in place, the surface temperature of the cold iron source C reaches a peak, and beyond that Even if the amount of the cold iron source C is increased, almost no preheating effect associated with the increase can be recognized, and when the area A of the pan mouth 12 is 15.2 m ² , the cold iron source C of 9.0 ton or more is selected. Even if it is left in place, the value of the surface temperature of the cold iron source C reaches its peak, and even if the amount of the cold iron source C is increased further, the preheating effect associated with the increase cannot be recognized from experiments and investigations. It was.

  Accordingly, the following relationship is established between the weight of the cold iron source C to be placed and the area of the pan mouth 12 of the hot metal pan 2, thereby effectively exerting the preheating effect of the cold iron source C to be placed. It was found that the amount of heat released from the iron skin 14 of the hot metal ladle 2 can be reduced.

On the other hand, by covering the surface of the refractory 15 in the pan, in particular, the surface of the refractory 15 forming the pan bottom 11 with the cold iron source C, the release of heat from the pan 12 in the pan is reduced. It is said. As a result, the temperature of the pan bottom 11 decreases, and the release of radiant heat from the refractory 15 on the pan bottom 11 indicated by the Stefan-Boltzmann law is suppressed.
When the cold iron source is placed in the hot metal ladle 2 in this way, in this embodiment, the cold iron source C is placed in the hot iron pan 2 by a known means in the cold iron source charging facility 9. However, as the area of the pot opening 12 increases, the surface area of the pot bottom 11 to be covered by the cold iron source C to be placed increases. That is, the area of the pot bottom 11 depends on the area of the pot opening 12, and the weight of the cold iron source C to be placed also varies depending on the area of the pot opening 12.

  Here, when the pot opening 12 is substantially circular, the area of the pot opening 12 is proportional to the square of the radius. Further, it is considered that the volume of the cold iron source C that is sufficient to cover the pot bottom 11 below the pot opening 12 (the orthographic projection surface of the pot opening 12) is proportional to the cube of the radius. As a result, the following expression (1B ′) is established.

Further, when the area A of the pan mouth 12 is set to 12.6 m ² , the inventors of the present invention set the weight of the cold iron source C to 18 ton or less, and the cold iron source C causes the lower portion of the pan mouth 12 and the periphery thereof to be I found that I could not cover it. From this result and the above formula (1B ′), when the relationship of the following formula (1B) is established between the weight of the cold iron source C to be placed and the area of the pan 12, the cold iron source to be put in place. It was found that C can sufficiently cover the pan bottom 11 of the hot metal pan 2.

  Therefore, by setting the weight of the cold iron source C within a range that satisfies the following expression (1), the heat loss reduction effect of the cold iron source C that is placed in the pan with respect to the heat loss of the hot metal pan 2 is sufficiently obtained. It can be demonstrated.

FIG. 3 shows the relationship between the area of the pan mouth 12 (horizontal axis: m ² ) and the weight of the cold iron source C to be placed (vertical axis: ton / car), and a range satisfying the above formula (1). By setting the weight of the cold iron source C, the heat loss reducing effect of the cold iron source C can be effectively exhibited.
FIG. 4 shows the relationship between the weight of the cold iron source C to be placed (horizontal axis: ton / vehicle) and the heat loss reduction effect (vertical axis: Mcal) by the cold iron source C. As shown in FIG. 4, as the weight of the cold iron source C to be placed increases, the heat loss reduction effect due to the preheating of the cold iron source C and the overall heat loss reduction effect due to the heat loss reduction effect from the pot opening 12 increase. However, the heat loss reduction effect does not have linearity, and has reached a peak with an increase in the weight of the cold iron source C to be placed.

In view of this point, the inventors of the present application have examined the relationship between the cold iron source C to be placed and the hot metal received in the hot metal ladle 2 in which the cold iron source C is placed. As a result, if the cold iron source C is placed in excess, the cold iron source C remains undissolved and the temperature drop of the hot metal becomes remarkable, and not only the heat loss reduction effect of the cold iron source C is effectively exhibited, but also the hot metal is remarkable. It has been found that there is a possibility that the subsequent operation may be hindered by a temperature drop.
Therefore, the inventor of the present application conducted an experiment on the weight of the cold iron source C to be placed and the weight of the hot metal to be received. As a result, by setting the weight of the cold iron source C to be put in the range of the following formula (2), it is possible to dissolve all the cold iron source C and prevent a significant temperature drop of the hot metal. I find out what I can do.

Therefore, by making the weight of the cold iron source C to be placed satisfy the above formulas (1) and (2), the operation after the cold iron source C is placed is not hindered, and the The heat loss reduction effect of the cold iron source C is effectively exhibited.
Further, in the steelmaking process, as shown in FIG. 5, the steelmaking process includes a discharge place 21 and a removal equipment 22 for discharging hot metal upstream of the dephosphorization converter 4A, and the hot metal discharged to the discharge place 21 is provided. A configuration in which the hot metal ladle 2 conveys to either the dephosphorization converter 4A or the decarburization converter 4B can be employed. Here, in the route in which the hot metal is conveyed to the decarburization converter 4B by the hot metal ladle 2, the hot metal is dephosphorized while the hot metal is being conveyed by the hot metal ladle 2. And the hot metal ladle 2 is returned to the discharge place 21 after paying out the hot metal after the dephosphorization process to the decarburization converter 4B. Alternatively, after the hot metal is charged into the hot metal ladle 2 at the discharge place 21 and conveyed to the decarburization converter 4B without dephosphorizing the hot metal, the hot metal is discharged to the decarburization converter 4B, It is also possible to adopt a configuration in which the hot metal ladle 2 that has become empty is returned to the dispensing place 21.

Further, in the route in which the hot metal is transported to the dephosphorization converter 4A by the hot metal ladle 2, the hot metal ladle 2 transports the hot metal from the discharge place 21 to the dephosphorization converter 4A via the degassing equipment 22, and in the pot. After the hot metal is discharged to the dephosphorization converter 4A, it is returned to the discharge place 21.
Here, in the dephosphorization process, gas acid (oxygen gas) and solid acid (iron oxide) are added to the molten iron together with lime as a dephosphorization material. The reaction with the gaseous acid is an exothermic reaction, and there is no possibility that the temperature of the hot metal is lowered. However, since the treatment with the gaseous acid is inefficient, a large amount of oxygen gas must be blown into the hot metal, and as a result, the carbon in the hot metal required as a heat source for the blowing process in the decarburization converter 4B is reduced. There is a concern that carbon dioxide (CO _x ) may be consumed more than necessary due to the reaction with the gaseous acid. In addition, the reactant adhering to the refractory in the furnace of the receiving vessel (in this embodiment, the hot metal ladle 2 or the dephosphorization converter 4A) that undergoes dephosphorization by spitting and burning of the reactant due to the reaction. There is a risk that the refractory in the furnace may be damaged at an early stage by an operation of removing the refractory.

For this reason, it is desirable to perform the dephosphorization treatment with a solid acid ratio larger than a gas-acid ratio. However, the dephosphorization treatment with solid acid is an endothermic reaction as a whole, and when the solid acid ratio is increased, a large amount of heat is consumed in the hot metal, which causes a significant decrease in the temperature of the hot metal.
In order to prevent such a temperature drop, it is desirable that the hot metal has a sufficient heat margin before the dephosphorization treatment. Therefore, in the steelmaking process shown in FIGS. 1 and 5, the inventor of the present application determines the weight of the cold iron source C placed in the hot metal ladle 2 in the following formula (3) when considering the temperature drop of the hot metal due to the dephosphorization process. It has been found that by setting the following, the amount of heat of the hot metal is deprived by the cold iron source C, but the heat margin of the hot metal for the dephosphorization treatment can be sufficiently maintained.

By setting the weight of the cold iron source placed in the range of the above formula (3), it is possible to increase the solid acid ratio in the dephosphorization process. Thereby, not only can the ratio of gas acid (heating material) be reduced depending on the temperature state of the hot metal, but also the suppression of carbon dioxide emission by dephosphorization treatment, the improvement of the productivity of the converter 3, The service life of the receiving container is extended.
By the way, in the steelmaking process shown in FIGS. 1 and 5, the time required to put the cold iron source in the empty hot metal ladle varies depending on the hot metal supply amount from the blast furnace 1 and the operating condition of the converter 3. To do. Then, the amount of heat remaining in the hot metal ladle 2 after completion of the exhausting process varies depending on the required time as described above.

  The inventors of the present application have found that the heat radiation from the completion of hot metal discharge to the start of placing the cold iron source C affects the heat radiation from the iron skin 14. The inventors of the present application have found that when the area of the pan opening 12 is constant, the weight of the cold iron source C varies linearly with respect to the required time. Therefore, in the above formula (1A), the proportional constant on the right side is divided by the average time of 15 minutes in the actual operation of the required time, and the required time is introduced as a variable in this term, and the cold iron source C is The following formula (4A) in consideration of heat radiation from the hot metal ladle 2 before placing was obtained.

In the present embodiment, the cold iron is used as the cold iron source C to be placed as described above. On the other hand, it is extremely difficult to insert hot metal ingots having the specifications as shown in FIG. 6 and coarse converter dust as the cold iron source C to be placed in view of the reduction of HMR and recycling of scrap. preferable. Even in actual operation, it is often used as a cold iron source C in which the molten metal, converter coarse dust, and the like are placed.
By the way, in the said embodiment, it is supposed that the refractory 15 of the pan bottom 11 will be covered by throwing in the pan the cold iron source C of the weight prescribed | regulated by the said Formula (1B). Here, when it employ | adopts as the cold iron source C which puts in one or several cold iron sources C among the said multiple types of said cold iron sources C, the weight of the cold iron source C for covering the refractory 15 Varies depending on the average bulk specific gravity of the cold iron source C to be placed.

Therefore, the inventors of the present invention introduced the average bulk specific gravity of the cold iron source C as a variable into the above formula (1B), and the proportional constant was determined to be a general average bulk specific gravity of 3.6 in actual operation. By dividing by (ton / m ³ ), the following formula (4B) in consideration of the type of cold iron source C to be placed was obtained.

  Thereby, the following formula (4) is obtained.

In the formula (4), the weight of the cold iron source C is defined in consideration of the relationship between the time from the completion of hot metal discharge to the start of placing the cold iron source C and the bulk specific gravity of the cold iron source C. As a result, by setting the weight of the cold iron source C placed in the hot metal ladle 2 within a range satisfying the formula (4) and the formula (2) or the formula (3), the weight is more realistic. Will be.
Hereinafter, examples will be described together with comparative examples to demonstrate the effects of the present invention.
FIG. 7 is a table for Examples 1 to 8 and Comparative Examples 1 to 7 in which the present invention is applied to the hot metal ladle 2 for conveying hot metal from the blast furnace 1 to the dephosphorization converter 4A of the converter 3 shown in FIG. The heat loss reduction effect by the cold iron source C was compared.

Here, in Examples 1-8 and Comparative Examples 1-7, the capacity | capacitance of the hot metal ladle 2 is 16 m < ³ >, and the time from the putting start of the cold iron source C to the receiving in the blast furnace 1 is unified in 50 minutes. At the same time, the hot metal temperature at the start of the blast furnace 1 is specified in the range of 1480 ° C. to 1520 ° C., and the hot metal temperature at the time of hot metal discharge is 1280 ° C. to 1380 ° C. is doing. The time required for one cycle from the start of blast furnace acceptance to the start of blast furnace acceptance of the next heat was 340 minutes on average, and was in the range of 250 to 450 minutes.
In addition, the area A (m ² ) of the hot iron pan 12 of the hot metal ladle 2, the time t (minutes) from the completion of the hot metal discharge to the placement of the cold iron source C, the hot metal received after the cold iron source C is placed. The conditions of the weight W _p (ton) and the weight W _i (ton) of the cold iron source C to be placed are set to different values in Examples 1 to 8 and Comparative Examples 1 to 7, respectively. In Comparative Example 1, the cold iron source C is not placed.

Furthermore, in Example 1 and Example 2, it is assumed that the weight of the cold iron source C to be placed satisfies at least the above formulas (1) and (2), and in Examples 3 and 4, It is assumed that the weight of the cold iron source C to be placed satisfies at least the above formulas (1) and (3), and in Examples 5 and 6, the weight of the cold iron source C to be placed is at least the above formula ( 2) and Equation (3) are satisfied, and in Example 7 and Example 8, the weight of the cold iron source C to be placed shall satisfy at least the above Equation (3) and Equation (4). .
In Comparative Examples 4 and 7, and Examples 3, 4, 7, and 8, the hot metal in the hot metal ladle 2 is subjected to dephosphorization. Here, in the dephosphorization treatment, the treatment time is set to 10 minutes, the hot metal temperature after the dephosphorization treatment is defined as a range of 1280 ° C to 1320 ° C, and gaseous oxygen is blown onto the hot metal surface from the top blowing lance. At the same time, quicklime, iron ore, and converter slag are added upward in the hot metal.

In addition, as the operation results, from the surface temperature (° C.) just before receiving the cold iron source C located below the pan mouth 12, the hot metal temperature measured in the main blast furnace cast iron immediately after the start of receiving and the start of receiving The temperature drop (° C.) indicating the temperature difference from the hot metal temperature in the hot metal ladle after 50 minutes, the difference in temperature difference between each example (° C.) with respect to Comparative Example 1, and the gas in the example where dephosphorization treatment was performed The amount of acid input (Nm ³ / ton) is shown.
Moreover, when calculating the heat loss reduction effect of each example in the effect, the heat loss reduction effect includes the heat dissipation loss reduction effect (Mcal) and the heat loss reduction efficiency (%) from the pan 12 and the preheating of the cold iron source C. The heat loss reduction effect (Mcal) and heat loss reduction efficiency (%) from the iron skin due to the effect, and the overall heat loss reduction effect (Mcal) and heat loss reduction efficiency (%) combining these two effects are shown. Yes.

Here, the heat loss reduction efficiency is the ratio of the heat loss reduction effect when the cold iron source is put in place before receiving with respect to the case where the cold iron source is put in after receiving. A specific definition of the reduction effect is shown in FIG.
In addition to this, as an effect, the remaining amount of molten iron (ton) of the cold iron source C, the weight of the molten iron (ton) solidified and left in the hot metal ladle 2, and the fire resistance provided around the dephosphorization converter 4A The damage rate (mm / heat) per process of an object is shown.
As is clear from FIG. 7, in the case of Comparative Examples 2 to 7 that do not satisfy the conditions of the present invention, the low heat loss reduction effect, the low heat loss reduction efficiency (about 20%), the melting of the cold iron source C Although one or more of the remaining solidified hot metal residue and the early refractory tendency of the refractory are observed, according to Examples 1 to 8 satisfying the conditions of the present invention, a good heat loss reduction effect and heat Loss reduction efficiency (approx. 40%) is recognized, and there is no residual melting of the cold iron source C, no residual solidified hot metal, no tendency to early damage of the refractory, etc., and the heat loss reduction effect of the cold iron source C is effective In addition, the possibility of hindering other processes and the dephosphorization converter 4A is solved.

FIG. 8 shows the present invention with respect to a cold iron source placed in a hot metal ladle 2 that conveys hot metal from the discharge place 21 of the converter facility 3 shown in FIG. 5 to the dephosphorization converter 4A or the decarburization converter 4B. For Examples 9 to 16 and Comparative Examples 8 to 14 to which A was applied, the effect of reducing the heat loss by the cold iron source C was compared.
Here, in Examples 9 to 16 and Comparative Examples 8 to 14, the capacity of the hot metal ladle 2 is 42 m ³ , and the time from the start of placing the cold iron source C to the receiving at the dispensing place 21 is unified in 15 minutes. At the same time, the hot metal temperature at the start of the blast furnace 1 is 1480 ° C. to 1520 ° C., and the hot metal temperature at the hot metal discharge is 1280 ° C. to 1380 ° C. It prescribes.

The time required for one cycle from the start of receiving at the payout place 21 to the start of receiving at the next heat payout place 21 was 55 minutes on average, ranging from 45 to 65 minutes.
In Comparative Examples 11 and 14, and Examples 11, 12, 15 and 16, a dephosphorization process is performed. Here, in the dephosphorization treatment, the treatment time is set to 10 minutes, the hot metal temperature after the dephosphorization treatment is defined as a range of 1280 ° C to 1320 ° C, and gaseous oxygen is blown onto the hot metal surface from the top blowing lance. At the same time, quicklime, iron ore, and converter slag are added upward in the hot metal.

Moreover, it is the same as that of the said Examples 1-8 and Comparative Examples 1-7 about the point which applies each formula to these Examples 9-16 and Comparative Examples 8-14, and confirms the operation performance and effect.
As is clear from FIG. 8, in the case of Comparative Examples 9 to 14 that do not satisfy the conditions of the present invention, the low heat loss reduction effect, the low heat loss reduction efficiency (about 15%), the melting of the cold iron source C Although any one or more of the remaining solidified hot metal residue and the tendency to early damage of the refractory are observed, according to Examples 9 to 16 satisfying the conditions of the present invention, a good heat loss reduction effect and heat Loss reduction efficiency (approx. 40%) is recognized, and there is no residual melting of the cold iron source C, no residual solidified hot metal, no tendency to early damage of the refractory, etc., and the heat loss reduction effect of the cold iron source C is effective In addition, the possibility of hindering other processes and the dephosphorization converter 4A is solved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments. For example, it is possible to perform a desulfurization process after the hot metal being conveyed is removed by the hot metal ladle 2 and then a process of discharging the hot metal to the dephosphorization converter 4A.
Alternatively, it is possible to perform a dephosphorization process and a desulfurization process after the hot metal being conveyed is removed by the hot metal ladle 2, and then the hot metal is discharged to the decarburization converter 4B.
The dephosphorization process may be performed until the hot metal charged in the hot metal ladle 2 is discharged to the decarburization converter 4B, and the hot metal received in the hot metal hot pot 2 is discharged to the receiving vessel. Of course, the hot metal may be dephosphorized after the hot metal is discharged into the receiving container.

It is a figure which shows the flow of a steel manufacturing process. It is a side view which cuts and shows a hot metal ladle. It is a figure which shows the optimal range of the weight of the cold iron source put. It is a figure which shows a heat loss reduction effect. It is a figure which shows the flow of another steelmaking process. It is a figure which shows the specification of a cold iron source. It is a figure which compares and shows an Example and a comparative example. It is a figure which shows the time-dependent change of the surface temperature of the cold iron source put. It is a list figure which shows the definition of a heat loss reduction effect.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Hot metal ladle 3 Converter equipment 4A Dephosphorization converter 4B Decarburization converter 9 Cold iron source input equipment 11 Pan bottom 12 Pan mouth 14 Iron skin 15 Refractory C Cold iron source

Claims (4)

Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The weight of the cold iron source placed in the empty hot metal ladle is set so as to satisfy the equations (1) and (2). To supply cold iron source

Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The hot metal is dephosphorized before the received hot metal is discharged into the receiving container, and the cold iron source is placed in the empty hot metal pan. A method for charging a cold iron source into a hot metal ladle, characterized in that the weight is set so as to satisfy the expressions (1) and (3).

Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The weight of the cold iron source placed in the empty hot metal ladle is set so as to satisfy the equations (4) and (2). To supply cold iron source

Discharge the hot metal in the hot metal ladle into the receiving container, and put the cold iron source at the bottom of the hot metal hot pot until the hot metal is charged into the empty hot metal hot pot, and then put the hot metal in the hot metal hot pot. The hot metal is dephosphorized before the received hot metal is discharged into the receiving container, and the cold iron source is placed in the empty hot metal pan. A method for charging a cold iron source into a hot metal ladle characterized in that the weight is set so as to satisfy the expressions (4) and (3).

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