JP2021025058A - Melting method of cold iron source in hot metal transport container - Google Patents

Abstract

To prevent at the time of charging, hot metal from scattering due to impact of a cold iron source dropping, and rapid reaction caused between hot metal and water adhering to the cold iron source, even when the hot metal remains in a hot metal transport container, in a melting method of the cold iron source in which the cold iron source is charged into a hot metal transport container so as to melt the cold iron source with sensible heat of the hot metal poured subsequently into the hot metal transport container.SOLUTION: In the melting method of the cold iron source in the hot metal transport container according to the present invention, a cold iron source 13 is charged in a hot metal transport container 1, and the cold iron source is melt with the sensible heat of hot metal 2 tapped from a blast furnace and poured into the hot metal transport container. The cold iron source is charged into the hot metal transport container after solidifying residual hot metal 8 remaining in the hot metal transport container, when the hot metal remains in the hot metal transport container before the cold iron source is charged into the hot metal transport container.SELECTED DRAWING: Figure 1

Description

The present invention is a hot metal transport container in which a cold iron source is charged in a hot metal transport container, and then the cold iron source is melted by the actual heat of the hot metal that is ejected from a blast furnace and injected into the hot metal transport container. Regarding the melting method of the cold iron source in.

Steelmaking process for the purpose of increasing crude steel production beyond the capacity of molten iron production facilities such as blast furnaces and electric furnaces, or for the purpose of preventing global warming by suppressing carbon dioxide emissions in the steel production process. Operations using cold iron sources such as iron scrap and direct reduced iron are widely practiced in Japan.

Among them, a cold iron source is charged in advance in a hot metal transport container represented by a torpedo car or an open radle, and the hot metal discharged from the blast furnace is received by the hot metal transport container. At the time of pig ironing, an operation of melting a cold iron source charged in advance by the actual heat of the hot metal received is widely practiced (see, for example, Patent Document 1). Further, as a device used when pre-loading the cold iron source into the hot metal transport container, a heavy machine is generally used because it is easy to install (see, for example, Patent Document 2).

By the way, in recent years, in the steel manufacturing process, it has been requested to minimize the amount of auxiliary raw materials used and the amount of waste generated. In order to meet this demand, functional separation in the steelmaking refining process has been carried out for the purpose of increasing the reaction efficiency of the refining medium solvent, and impurities are removed from the desiliconization treatment, desulfurization treatment, and dephosphorization treatment in the hot metal transport vessel. The processing is done separately. In these impurity removal treatments, the respective impurity removal reactions are advanced by charging each of the refining medium solvents into the hot metal transport container and incorporating each impurity into the refining medium solvent.

The refining medium solvent after reacting with impurities exists as slag on the hot metal bath surface, and by removing this slag from the hot metal transport container, each impurity removal treatment is completed. Therefore, after each impurity removal treatment, the slag existing on the hot metal bath surface is scraped out from the hot metal transport container by using a slag removing device such as a slag dragger. At that time, before a part of the refining medium solvent is scraped out, it solidifies and adheres at the mouth of the hot metal transport container to form a weir at the mouth of the hot metal transport container.

After that, the hot metal in the hot metal transport container is discharged from the hot metal transport container to a converter charging pot or the like at a steelmaking factory. At that time, if the hot metal is discharged from the hot metal transport container with a weir at the mouth to a converter charging pot, etc., the weir at the mouth obstructs the discharge of the hot metal, and all of the hot metal cannot be discharged, so the hot metal transport container A part of the hot metal remains inside.

If a part of the hot metal remains in the hot metal transport container, then when the cold iron source is charged into the hot metal transport container by a heavy machine before receiving the hot metal again, it is due to the drop impact when the cold iron source is charged. There is a concern about safety problems and equipment damage due to the scattering of hot metal and the rapid reaction (steam explosion) between the hot metal and the water adhering to the cold iron source.

Since the safety of workers is a matter that should be considered with the highest priority, if the hot metal remains in the hot metal transport container as described above, the charging of the cold iron source into the hot metal transport container must be stopped. It was not possible to obtain it, and the production of hot metal was forced to decrease due to the suspension of the charging of cold iron sources.

Japanese Patent No. 4438562 JP-A-2007-113056

The present invention has been made in view of the above circumstances, and an object of the present invention is to charge a cold iron source in a hot metal transport container, and then cool the hot iron by the actual heat of the hot metal injected into the hot metal transport container. When melting the iron source, even if the hot metal remains in the hot metal transport container, the hot metal is scattered due to the drop impact when the cold iron source is charged, and the hot metal and the moisture adhering to the cold iron source suddenly become scattered. It is an object of the present invention to provide a method for melting a cold iron source in a hot metal transport container, which can prevent a reaction in advance.

The gist of the present invention for solving the above problems is as follows.
[1] A hot metal transport container in which a cold iron source is charged into a hot metal transport container, and then the cold iron source is melted by the actual heat of the hot metal that is ejected from the blast furnace and injected into the hot metal transport container. It is a method of melting the cold iron source of
When hot metal remains in the hot metal transport container before the cold iron source is charged into the hot metal transport container, the hot metal remaining in the hot metal transport container is solidified, and then the cold iron source is put into the hot metal transport container. A method for melting a cold iron source in a hot metal transfer container, which is characterized by charging.
[2] A granular substance having a particle size that does not cause the hot metal to scatter and that does not cause a rapid reaction between the hot metal and the water adhering to the granular substance is put into the hot metal transport container, and the sensible heat of the hot metal is added to the granular substance. The method for melting a cold iron source in a hot metal transport container according to the above [1], which comprises absorbing latent heat to solidify the hot metal remaining in the hot metal transport container.
[3] The method for melting a cold iron source in a hot metal transport container according to the above [2], wherein the particulate matter has a particle size of 80 mm or less.
[4] The granular substance is one or more selected from the group of coke powder, magnetic desulfurized slag, and oxides of metal elements having a higher ionization tendency than aluminum. [2] or the method for melting a cold iron source in the hot metal transport container according to the above [3].

According to the present invention, when hot metal remains in the hot metal transport container, the remaining hot metal is solidified and then the cold iron source is charged. Therefore, even if the hot metal remains in the hot metal transport container, it is cooled. It is realized to prevent the hot metal from scattering due to the drop impact when the iron source is charged and the rapid reaction between the hot metal and the water adhering to the cold iron source.

It is a flow chart which shows the processing process of the melting method of the cold iron source in the hot metal transport container which concerns on this invention. It is a photograph of the bottom of the hot metal pot before and after adding coke powder. It is a photograph of the bottom of the hot metal pot before and after the introduction of the magnetic deposit of desulfurized slag. It is a figure which shows the change of the cold iron source charging implementation ratio before and after applying this invention.

Hereinafter, the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a diagram showing an embodiment of the present invention, and is a flow chart showing a processing step of a method for melting a cold iron source in a hot metal transport container according to the present invention. Here, the hot metal transport container is a hot metal melted in a blast furnace, receives hot metal from the blast furnace, transports the hot metal to the steelmaking factory in the next process, and transports the hot metal to the steelmaking factory's equipment. It is a facility that repeats the cycle of paying out to (converter charging pot, hot metal, etc.) and then returning to the blast furnace to receive hot metal.

Typical examples of the hot metal transport container are a torpedo wagon that runs on a rail and a hot metal pot that moves on a trolley that moves on the rail (also called a "blast furnace pot"). Shows the case where a hot metal pot is used as a hot metal transport container. Hereinafter, the processing process will be described from the receiving stage.

The hot metal pot 1 in which the cold iron source 13 is preloaded is placed directly under the tilting gutter 3 of the blast furnace, and the hot metal gutter (not shown) that is taken out of the blast furnace and installed on the casting floor of the blast furnace is poured down. The hot metal 2 that falls from the hot metal trough to the tilting gutter 3 is received through the hot metal pouring gutter 3. The cold iron source 13 charged in the hot metal pot 1 is preheated by the heat possessed by the refractory material 1a installed in the hot metal pot 1, and the sensible heat of the hot metal 2 injected from the tilting gutter 3 is combined. Dissolve in. As the cold iron source 13 to be used, iron scrap, directly reduced iron, cold pig iron and the like are suitable.

After receiving the hot metal, the hot metal pot 1 is pulled out from directly under the tilting gutter 3, and the hot metal pot 1 containing the hot metal 2 is transported to the pretreatment center where the hot metal pretreatment is performed. At the pretreatment center, one or more of the desiliconization treatment, the dephosphorization treatment, and the desulfurization treatment of the hot metal 2 are carried out.

Here, the desulfurization treatment is a treatment in which an oxygen source or an oxygen source and a CaO-based medium solvent are added to the hot metal ₂ to oxidize and remove silicon in the hot metal as SiO 2, and the desulfurization treatment is a treatment in which the hot metal 2 is formed. It is a process of adding an oxygen source and a CaO-based medium solvent to oxidize phosphorus in the hot metal and _{incorporating it into the CaO-based medium solvent as 3CaO · P 2} O ₅ to oxidize and remove the phosphorus in the hot metal. Is a process of adding a CaO-based desulfurizing agent or metallic magnesium to the hot metal 2 to reduce and remove oxygen in the hot metal. When two or more of the desiliconization treatment, the dephosphorylation treatment, and the desulfurization treatment of the hot metal 2 are carried out, the desiliconization treatment is carried out before the desiliconization treatment, and the desulfurization treatment is the desiliconization treatment and the desulfurization treatment. The order does not matter.

In any of the hot metal pretreatments, after the treatment, silicon, phosphorus, and sulfur in the hot metal to be removed are incorporated into the slag existing on the hot metal, and by removing this slag from the hot metal pan 1, the slag is removed. Each hot metal pretreatment is completed. If the next step is performed without removing the slag, the element to be removed returns from the slag side to the hot metal side, the content of the element to be removed in the hot metal increases, and the efficiency of the hot metal pretreatment deteriorates.

FIG. 1 illustrates a desulfurization treatment using a CaO-based desulfurization agent as a hot metal pretreatment. In the desulfurization treatment of hot metal 2 using a CaO-based desulfurization agent, the impeller 4 is immersed in the hot metal 2, the impeller 4 is rotated at a predetermined rotation speed, and the CaO-based desulfurization agent added on the bath surface of the hot metal 2 is hot metal. It is involved in the CaO-based desulfurizing agent and reacts with the sulfur in the hot metal, and the sulfur in the hot metal is incorporated into the CaO-based desulfurizing agent as CaS. After the desulfurization treatment, the CaO-based desulfurization agent containing CaS floats on the hot metal bath surface as slag 5.

In order to remove the slag 5 from the hot metal pot 1, after the desulfurization treatment, the hot metal pot 1 is tilted to the extent that the hot metal 2 does not flow out, and the slag 5 is scraped out by the slag dragger 6. At that time, before a part of the slag 5 made of the CaO desulfurizing agent is scraped out, it solidifies and adheres at the mouth of the hot metal pot 1 to form a weir (not shown) at the mouth of the hot metal pot 1. The slag dragger 6 is a device that moves the arm 6a back and forth in the horizontal direction and scrapes the slag 5 in the hot metal pot 1 from the upper end portion of the hot metal pot 1.

After removing the slag 5, the hot metal pan 1 containing the hot metal 2 that has been subjected to the hot metal pretreatment is transported to the steelmaking factory. Then, the hot metal 2 is discharged from the hot metal pot 1 to the equipment belonging to the steelmaking factory (converter charging pot, torpedo wagon, etc.). In FIG. 1, a converter filling pot 7 is illustrated as equipment belonging to a steelmaking factory. The converter charging pot 7 is a container for charging the hot metal 2 into a converter (not shown).

When the hot metal 2 is discharged from the hot metal pot 1 having a weir with a slag 5 at the mouth to the converter charging pot 7, the weir at the mouth hinders the smooth discharge of the hot metal 2 and discharges all of the hot metal 2. This is not possible, and a part of the hot metal 2 may remain in the hot metal pot 1. In the present specification, the hot metal 2 remaining in the hot metal pot 1 is referred to as "residual hot metal 8". When a part of the hot metal 2 remains in the hot metal pot, the residual hot metal 8 is scattered due to the drop impact at the time of charging the cold iron source 13 in the subsequent charging of the cold iron source 13 into the hot metal pot 1. There is a concern about safety problems and equipment damage due to the rapid reaction (steam explosion) between the residual hot metal 8 and the water adhering to the cold iron source 13.

Therefore, in the present invention, in order to prevent the above safety problem and equipment damage, after the hot metal 2 is discharged from the hot metal pot 1, it is checked whether or not there is residual hot metal 8 in the hot metal pot 1. The presence or absence of the residual hot metal 8 is checked by a visual check by an operator, a check by shooting with an optical camera, or the like. Then, when the hot metal 2 remains in the hot metal pot 1, the hot metal 2 remaining in the hot metal pot 1 is solidified, that is, the residual hot metal 8 is solidified, and then the cold iron source 13 is charged into the hot metal pot 1. .. If the hot metal 2 does not remain in the hot metal pot 1, the cold iron source 13 is charged into the hot metal pot 1 without any treatment.

The residual hot metal 8 solidifies even if the hot metal pot 1 is allowed to cool in the atmosphere, but it takes time to complete the solidification. Therefore, in order to shorten this time, grains of the residual hot metal 8 do not scatter. The granular substance 10 having a diameter and which does not cause a rapid reaction between the residual hot metal 8 and the water adhering to the granular substance 10 is put into the hot metal pan 1, and the sensible heat of the residual hot metal 8 is added to the put in the granular substance 10. It is preferable to absorb the latent heat and solidify the residual hot metal 8 in the hot metal pot. FIG. 1 shows how the particulate matter 10 contained in the hopper 9 is put into the hot metal pan 1.

Specifically, the particle size of the granular substance 10 is 80 mm or less, and the granular substance 10 is selected from the group of coke powder, magnetic deposits of desulfurized slag, and oxides of metal elements having a higher ionization tendency than aluminum. It is preferably one kind or two or more kinds. The input amount of the particulate matter 10 is preferably 150 to 500 kg. If the particle size of the particulate matter 10 is 80 mm or less, the residual hot metal 8 does not scatter. Further, when the input amount of the particulate matter 10 is 150 to 500 kg, the residual hot metal 8 can be surely solidified. The particle size of the particulate matter was measured using a sieve with a nominal opening specified in JIS-Z-8801-1.

The coke powder not only has a sufficient heat capacity to absorb the sensible heat and latent heat of the residual hot metal 8, but also the coke powder itself burns, and the combustion heat preheats the cold iron source 13 to be charged thereafter. can do. The magnetic deposit of the desulfurized slag is obtained by cooling the slag 5 produced by the desulfurization treatment of the hot metal 2 using a CaO-based desulfurizing agent, and then magnetically sorting and recovering the slag. The main component is iron iron, and the residual hot metal 8 It has a sufficient heat capacity to absorb sensible heat and latent heat.

In the case of an oxide of a metal element having a higher ionization tendency than aluminum, the heat capacity is inferior to that of the two substances, so that the input amount increases. However, oxides of metal elements that have a lower ionization tendency than iron oxidize hot metal as a solid oxygen source and cause an unexpected explosive reaction, whereas oxides of metal elements that have a higher ionization tendency than aluminum. Since it does not have the ability to oxidize hot metal, it can ensure the safety of charging equipment and workers, so it is suitable as an input for solidification.

When the residual hot metal 8 in the hot metal pot has been solidified, the cold iron source 13 is charged into the hot metal pot. To charge the cold iron source 13 into the hot metal pot, as shown in FIG. 1, the cold iron source 13 is magnetically attached to the lifting magnet 12 attached to the heavy machine 11 and lifted, and the lifting magnet 12 is demagnetized. A method in which the suspended cold iron source 13 is dropped into the hot metal pot and charged is preferable.

After charging a predetermined amount of the cold iron source 13 into the hot metal pot 1, the hot metal pot 1 is arranged directly under the tilting gutter 3 of the blast furnace, and waits for the hot metal 2 to be tapped from the blast furnace.

As described above, according to the present invention, when the hot metal remains in the hot metal transport container, the remaining hot metal is solidified and then the cold iron source is charged. Therefore, when the hot metal remains in the hot metal transport container. Even so, it is possible to prevent the hot metal from scattering due to the drop impact when the cold iron source is charged and the rapid reaction between the hot metal and the water adhering to the cold iron source.

In the above description, the case where the hot metal pan 1 is used as the hot metal transport container is described as an example, but the present invention can be carried out in accordance with the above even when the hot metal wheel is used as the hot metal transport container.

The present invention was carried out using a hot metal pot having a content of 200 tons, which is provided with a refractory material containing _{alumina (Al 2} O ₃ ) as a main component, as a hot metal transport container.

The hot metal from the blast furnace was received in this hot metal pot, and then the hot metal was subjected to a predetermined hot metal pretreatment (desulfurization treatment) and transported to a steelmaking factory. In a steelmaking factory, hot metal is discharged from a hot metal pot to a converter charging pot, and after the hot metal is discharged, when an operator visually observes 1 to 4 tons of residual hot metal, it is installed above the hot metal pot standby position. From the hopper, 150 to 500 kg of coke powder having a particle size of 8 to 20 mm was put into a hot metal pan as a granular substance for solidifying the hot metal.

If the residual hot metal is less than 1 ton by visual inspection, it has been confirmed that the residual hot metal solidifies by the time when the cold iron source is added only by allowing it to cool. Therefore, the particulate matter for solidifying the hot metal No addition was carried out.

As a result, it was confirmed that the residual hot metal was sufficiently solidified by adding coke powder. FIG. 2 shows photographs of the bottom of the hot metal pot before and after the addition of coke powder. As shown in FIG. 2, it can be confirmed that the residual hot metal is solidified by adding the coke powder. As a method of confirming whether or not the residual hot metal has solidified, it is also possible to incline the hot metal pot with respect to the horizon and check whether or not the residual hot metal moves.

After adding the coke powder, the hot metal pan is moved to the cold iron source charging place, and 7 tons of thick plate scraps and steel ingots are removed from the cold iron by the lifting magnet attached to the heavy machinery located at the cold iron source charging place. It was charged into a hot metal pot as a source. When the plate scraps and steel ingot scraps get wet due to rainfall, the water content is not controlled beyond stopping the charging to the hot metal pot. No abnormal reactions such as scattering of hot metal or steam explosion occurred when the cold iron source was charged into the hot metal pot by heavy machinery.

In this treatment process, the charged coke powder deprives the residual hot metal of sensible heat and latent heat to solidify the residual hot metal, so there was concern about the temperature effect on the hot metal received, but the amount charged to the cold iron source On the other hand, since the amount of coke charged was sufficiently small, no temperature effect on the hot metal was detected. Regarding the mass of residual hot metal, the amount of residual hot metal did not exceed 4 tons due to the size of the weir at the mouth of the hot metal pot and the shape of the hot metal pot, but the amount of particulate matter input was adjusted. By doing so, the present invention can be carried out even when residual hot metal exceeding 4 tons is generated.

Further, in the same hot metal pot, 300 to 500 kg of a magnetic deposit of desulfurized slag having a particle size of 80 mm or less was added instead of coke powder. In this case as well, it was confirmed that the residual hot metal was sufficiently solidified. FIG. 3 shows photographs of the bottom of the hot metal pot before and after the introduction of the magnetic deposit of desulfurized slag. As shown in FIG. 3, it can be confirmed that the residual hot metal is solidified by adding the magnetic deposit of the desulfurized slag. After that, when the cold iron source was charged by heavy machinery, no abnormal reactions such as hot metal scattering and steam explosion occurred.

FIG. 4 shows the change in the cold iron source charging implementation ratio before and after the application of the present invention. Fig. 4 shows three types: (1) cold iron source charging, (2) cold iron source charging impossible due to residual hot metal, and (3) cold iron source charging impossible due to reasons other than residual hot metal. It is a graph showing the total number of hot metal pots received in one month between the month when the invention was implemented and the same month of the previous year, that is, the number of times of receiving iron as a parameter (percentage).

As shown in FIG. 4, before the application of the present invention, the cold iron source charging implementation ratio was 30%, but by applying the present invention, "cold iron source charging impossible due to residual hot metal" is significantly increased. As a result, it was possible to increase the cold iron source charging implementation ratio to 48.8%, and as a result, it was possible to realize a monthly cold iron source charging of 2013 tons. In addition, "Cold iron source cannot be charged for reasons other than residual hot metal" means that the cold iron source gets wet due to rainfall and the charging of the cold iron source to the hot metal pot is stopped, and the next reception is due to the time schedule. The main cause is that the charging of the cold iron source to the hot metal pot was stopped because it was not in time for the hot metal.

1 Hot metal pot 1a Refractory 2 Hot metal 3 Tilt gutter 4 Impeller 5 Slag 6 Slag dragger 6a Arm 7 converter pot 8 Residual hot metal 9 Hopper 10 Granular material 11 Heavy machine 12 Lifting magnet 13 Cold iron source

Claims (4)

Cold iron in a hot metal transport container is charged with a cold iron source in a hot metal transport container, and then the cold iron source is melted by the apparent heat of the hot metal that is ejected from the blast furnace and injected into the hot metal transport container. A method of dissolving the source
When hot metal remains in the hot metal transport container before the cold iron source is charged into the hot metal transport container, the hot metal remaining in the hot metal transport container is solidified, and then the cold iron source is put into the hot metal transport container. A method for melting a cold iron source in a hot metal transfer container, which is characterized by charging. A granular substance having a particle size that does not cause the hot metal to scatter and that does not cause a rapid reaction between the hot metal and the water adhering to the granular substance is put into the hot metal transport container, and the sensible heat and latent heat of the hot metal are added to the granular substance. The method for melting a cold iron source in a hot metal transport container according to claim 1, wherein the hot metal remaining in the hot metal transport container is solidified by absorbing the hot metal. The method for melting a cold iron source in a hot metal transport container according to claim 2, wherein the particulate matter has a particle size of 80 mm or less. The granular substance is one or more selected from the group of coke powder, magnetic desulfurized slag, and oxides of metal elements having a higher ionization tendency than aluminum, according to claim 2 or The method for melting a cold iron source in the hot metal transport container according to claim 3.