JP2006070308A - Method for melting solid-iron source in molten iron carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for melting solid-iron source in a molten iron carrier by which even in the case of beforehand laying dephosphorized bare metal and/or desulfurized bare metal recovered at the slag-off time after dephosphorization and/or desulfurization of the molten iron, there is no possibility of phreatic explosion. <P>SOLUTION: A technique with which the solid iron source is beforehand laid into the molten iron carrying vessel, the molten iron from a blast furnace is received and this solid iron source is melted by using the sensible heat and stirring force, is improved. In this method, as the solid-iron source, the dephosphorized bare metal and/or the desulfurized bare metal which are agglomerated and solidified at the size of 200-1,500mm and recovered in the high temperature state of 100-600°C are used in the slag generated with the dephosphorization and/or the desulfurization of the molten during leaving the slag in the yard. In this time, it is preferable to beforehand lay the dephosphorized bare metal and/or the desulfurized bare metal into the molten iron carrier by using a heat-resistant hydraulic-type heavy machine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for melting a solid iron source in a hot metal transfer container, and more particularly to a technique for reusing desulfurized metal recovered at the time of discharge after hot metal ladle desulfurization as a solid iron source.

    Conventionally, in steelworks having a blast furnace, a solid iron source (generally called a cold iron source, which is often used at room temperature) such as iron scrap and mold iron is used as a part of the steelmaking raw material. It has been carried out (for example, Patent Document 1) that a hot metal melted in a blast furnace after being placed in the interior (for example, a kneading vehicle or the like) is used. This technology has been developed to actively utilize the heat dissipated into the atmosphere from an empty hot metal transfer container after the hot metal as a steelmaking raw material has been delivered to the converter. In addition, a technology for putting a small-diameter wet solid iron source into a hot kneaded car after the hot metal is discharged, tilting the kneaded car a plurality of times, heating and drying the solid iron source, and then receiving the hot metal Is also disclosed (see Patent Document 2). This is because small solid iron sources, such as granular iron and dust, have a large surface area per unit weight and a high moisture content, so that moisture remains without being evaporated even in a hot kneading vehicle. It was developed as a technology to prevent explosion. Therefore, since these techniques use a solid iron source other than the blast furnace hot metal as a steelmaking raw material, both are effective techniques when the amount of hot metal supplied from the blast furnace is insufficient.

  Furthermore, recently, with the widespread use of hot metal pretreatment, a large amount of materials different from the above-mentioned solid iron source has been generated. For example, desiliconization treatment using blast furnace hot metal, decanting iron, desiliconization using a kneading vehicle, dephosphorization, desulfurization treatment, and desulfurization treatment using a ladle are inevitable. This is because waste metal is removed and bullion (for example, desiliconized bullion, dephosphorized bullion, desulfurized bullion, etc.) is recovered during cooling. And if these bullion can be reused as a raw material for iron making, it will be very useful when the amount of hot metal supplied from the blast furnace is insufficient. In addition, a technique for dephosphorizing and desulfurizing the obtained hot metal again has been disclosed (see Patent Document 3). In addition, there are two types of desulfurization for hot metal pretreatment: using a kneading vehicle as a processing vessel and using a ladle. Desulfurization after desulfurization outside the furnace in a kneading vehicle or a suitable hot metal carrying vessel. A desulfurization site characterized in that the desulfurization metal contained therein is roughly separated from the desulfurization slag and is put into a kneading car or a suitable hot metal transport pan before receiving to perform the slag and external desulfurization. A method for reusing gold has also been proposed (see Patent Document 4). The hot metal desulfurization treatment in the kneading car is performed by using soda ash or lime-based flux as the refining agent and blowing it with the carrier gas through the lance immersed in the hot metal. Desulfurization is performed by using a lime-based flux as a refining agent, immersing the impeller in hot metal, and mechanically stirring.

  By the way, the bullion collected in the hot metal pretreatment is slag water cooled in the yard. There is a problem that the amount is limited. The dephosphorized metal and desulfurized metal are no exception, and the water content may be about 13% by mass and the combined water may be about 8% by mass. For this reason, there is a concern about problems such as bumping and steam explosion when placed in front of a chaotic vehicle or the like. For this reason, conventionally, the direct input to the converter is made.

However, when the dephosphorized metal and / or desulfurized metal is put into the converter, it contains a large amount of phosphorus (P) and sulfur (S), so the desulfurizing agent raw material in the hot metal desulfurization treatment before charging the converter Another problem that the unit greatly increases or the basic unit of dephosphorization agent in the converter arises, and it is desirable to place it in a hot metal transfer container from the viewpoint of desulfurization, dephosphorization treatment and thermal economy. However, Patent Document 3 does not show any description about this problem. Also, as a countermeasure, it is conceivable to apply the technique of Patent Document 2 in which the chaotic wheel is tilted after the pre-placement to evaporate and remove the water in advance, but this leads to a significant increase in the pre-place time, and efficient and high productivity. This will interfere with the steelmaking process that is desired to maintain the same. Furthermore, Patent Document 4 states that “It is easiest and most reliable to use a magnet roll as a method for roughly separating and recovering the metal from the desulfurization slag” and “prior to smashing and sizing the desulfurization slag. Although there is a description that “it is preferable”, no more specific technique is described. Presumably, there is a description in the example that “crushed and sized to a size of 25 to 150 mm”. Therefore, it is expected that the crushed and sized particles are cooled with water in advance.
JP 54-142116 A JP-A-5-239523 JP-A-8-193210 JP-A-55-94413

  In view of such circumstances, the present invention provides a hot metal transport container that does not cause a steam explosion even if a dephosphorized metal and / or desulfurized metal recovered at the time of dephosphorization and / or desulfurization after desulfurization is placed in advance. The object is to provide a method for dissolving solid iron sources at the same time.

  In order to achieve the above-mentioned object, the inventor has conducted earnest research on a method for recovering a bare metal at the time of dephosphorization of hot metal and / or waste after desulfurization, and has realized the results in the present invention.

  That is, in the present invention, the solid iron source is placed in advance in the hot metal transfer container, the hot iron from the blast furnace is received, and when the solid iron source is melted using the sensible heat and stirring force, the solid iron source is used as the solid iron source. The slag produced by dephosphorization and / or desulfurization of the hot metal was allowed to agglomerate and solidify in the slag at a size of 200 to 1500 mm while being left in the yard, and the dephosphorized metal recovered at a high temperature of 100 to 600 ° C. It is a melting method of the solid iron source in the hot metal transport container characterized by using desulfurized metal. In this case, it is preferable that the dephosphorized metal and / or the desulfurized metal is placed in advance in the hot metal transport container using a heat-resistant hydraulic heavy machine, or the hot metal transport container is a kneading vehicle.

  According to the present invention, the risk of a steam explosion when the desulfurized metal recovered at the time of discharge after hot metal desulfurization is placed in the hot metal transfer container is eliminated. Conventionally, desulfurized metal that has not been used much can be effectively reused as a solid iron source.

  Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.

  When desulfurized metal is put in front of the hot metal transport container and received, bumping and steam explosion are caused by cooling the slag discharged from the hot metal pretreatment container (mixing wheel, ladle, etc.) to the yard, We thought that there was a problem with the conventional bullion collection method of classifying the bullion that was agglomerated and solidified with grizzly etc. In other words, the bullion recovered by such a method not only encapsulates moisture but also starts to solidify before the agglomeration sufficiently proceeds, so the size is small and the specific surface area is large. Therefore, CaO tends to cause a hydration reaction.

  Therefore, the inventor considered that the risk of bumping or the like can be avoided if the metal is kept at a high temperature of 100 ° C. or higher until it is placed in the hot metal transfer container. And in order to do so, it was necessary to collect ingots at a temperature of at least 400 ° C. or higher.

  First, the inventor scrapes the dephosphorized and / or desulfurized slag left in the yard with a long reach shovel and applies it to grizzly (grid with steel rods arranged at regular intervals) to collect the solidified metal in a hot state. Tried. As a result, since water cooling was not performed, the aggregation of iron was promoted, and a total of 1.5 tons of a large metal having a diameter of 300 mm and a length of 1000 mm was successfully recovered. The average temperature of the bare metal measured with a radiation thermometer was 400 ° C.

  However, with this method, dust generation is severe when it is applied to the grizzly, and implementation cannot be accepted due to environmental problems.

  Next, while the dephosphorization and / or desulfurization slag was piled up in the yard, as shown in FIG. 1, an attempt was made to grasp only the metal 2 from the mountain of the dephosphorization and / or desulfurization slag 1. For this purpose, a heat-resistant heavy machine 3 is required. However, it was decided to protect and use each part of the tip "iron claw type" hydraulic heavy machine with a heat-resistant material.

  As a result, about 4 tons of ladle desulfurization metal with a diameter of 300 mm or more x length of 500 mm can be recovered in 5 minutes, and dust generation is so small that it cannot be observed with the naked eye. I was able to judge that there was no. Therefore, if there is a heat-resistant heavy machine 3 that can withstand long-term hot use and a transporting vehicle (such as a dump truck), it is considered that the bullion collected by the implementation of this method can be used in advance, which is important for the present invention. It was a requirement.

  In the present invention, the size of the dephosphorized metal and / or desulfurized metal is set to 200 mm to 1500 mm. However, if it is 200 mm or less, the specific surface area is increased to prevent moisture absorption and the like from occurring easily. This is because when it exceeds 1500 mm, it is difficult to place the vehicle in front of a chaotic vehicle or the like. As a matter of course, it is preferable that the hydraulic heavy machine used in front of the chaotic vehicle or the like is also heat resistant. The reason why the temperature of the bare metal is set to 100 to 600 ° C. is that water absorption may occur when the temperature is lower than 100 ° C., and the heat resistance temperature of heavy machinery is exceeded when the temperature exceeds 600 ° C.

  Generally, in a steelmaking factory, hot metal from a blast furnace is desiliconized using a tilting iron, received in a kneading car as a hot metal transport container, dephosphorized, charged into a converter, and molten steel is supplied by oxygen blowing. Melt. At that time, if necessary, the ladle is used as a processing vessel, and a desulfurization process is performed in which a desulfurizing agent is introduced into the hot metal held therein and mechanically stirred with an impeller or the like. In the present invention, the iron content accompanying the slag generated by the dephosphorization and / or desulfurization treatment is reused as a dephosphorization metal and / or desulfurization metal for a steelmaking raw material.

  Dephosphorization metal and / or desulfurization metal which piles up dephosphorization and / or desulfurization slag discharged to the yard and is still agglomerated and solidified at the bottom while the surface temperature of the slag is 800-600 ° C. Was grabbed with heavy machinery. The heavy machinery used is a hydraulic heavy machinery in which a hydraulic hose is covered with a heat-resistant material, a stainless steel strip is wound around, and a hydraulic cylinder is covered with a steel plate cover. As a result, the picking work for 5 minutes can be carried out, and the temperature of the recovered dephosphorized metal and / or desulfurized metal was 400 ° C. on average. This bullion is transported by a dump truck with a blast furnace laid on the carrier and insulated, and is placed in front of the empty kneading car using a heat-resistant heavy machine, receiving hot metal from the blast furnace, and using its sensible heat and stirring power. The pre-removed dephosphorized metal and / or desulfurized metal was dissolved. Upon melting, no hot metal bumping, steam explosion, etc. occurred. Here, the weight of the hot metal received is 300 tons, and the weight of the pre-dephosphorized metal and / or desulfurized metal is 3 tons.

  Then, as shown in FIG. 2, the kneaded vehicle after receiving was transported to a steelmaking factory through a normal dephosphorization process and a desulfurization process, and discharged to a converter. At the time of paying out to the converter, no undissolved material is observed, and it is clear that dephosphorized metal and / or desulfurized metal can be effectively used as a steelmaking raw material according to the present invention.

It is a schematic diagram explaining the method of collect | recovering hot metal from the dephosphorization and / or desulfurization slag piled up in the yard. It is a flowchart explaining the melt | dissolution method of the solid iron source in the hot metal conveyance container which concerns on this invention.

Explanation of symbols

1 Dephosphorization and / or desulfurization slag 2 Metal 3 Heat resistant heavy machinery

Claims (3)

When the solid iron source is placed in the hot metal transfer container in advance, the hot metal from the blast furnace is received, and when the solid iron source is melted using the sensible heat and stirring force,
As the solid iron source, slag produced by dephosphorization and / or desulfurization of hot metal was allowed to stand in the yard, and was aggregated and solidified at a size of 200 to 1500 mm in the slag and recovered at a high temperature of 100 to 600 ° C. A method for dissolving a solid iron source in a hot metal transfer container, characterized by using dephosphorized metal and / or desulfurized metal.   2. The method for melting a solid iron source in a hot metal transport container according to claim 1, wherein the dephosphorized metal and / or desulfurized metal is placed in advance in the hot metal transport container using a heat-resistant hydraulic heavy machine. The method for melting a solid iron source in a hot metal transport container according to claim 1 or 2, wherein the hot metal transport container is a kneading vehicle.

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