Converter steelmaking method
The converter steelmaking method addresses the challenge of producing steel with varying CO2 emissions and impurity management by identifying and adjusting raw materials, enabling flexible production and quality control.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- JFE STEEL CORP
- Filing Date
- 2025-12-18
- Publication Date
- 2026-07-02
Smart Images
Figure JP2025044233_02072026_PF_FP_ABST
Abstract
Description
Converter steelmaking process
[0001] This invention is CO ２ This relates to a converter steelmaking method that can produce different types of steel products with varying emission levels.
[0002] Due to growing awareness of global environmental protection, CO2 ２ CO2 reduction is required in all fields. Demand for steel products is also increasing. ２ Various technological developments are underway to reduce, recover, and sequestrate emissions. All steel products are low CO2. ２ While it is preferable to produce carbon-neutral materials using emissions, this is difficult from a cost and productivity standpoint, and it is necessary to produce them separately as needed. Meanwhile, there is a growing need for carbon-neutral (CN) materials among steel product users, and in some cases CO ２ There is also a demand for steel products with lower CO2 emissions. In this context, steel manufacturers are seeking orders for normal levels of steel products and low-CO2 emissions. ２ We are currently in a transitional period where orders for steel products are mixed together. In other words, in addition to the conventional required characteristics such as strength, ductility, and composition range, CO ２ Emissions are increasingly being added to the list of required characteristics.
[0003] Patent Document 1 discloses a method for determining the molten iron components after removing components from the molten iron in a molten iron reserve facility when allocating molten iron from a molten iron transport vehicle to a converter charge. The determination method described in Patent Document 1 has four steps. The first step is to store in a first storage means the arrival order of molten iron transport vehicles transported to the steelmaking plant, the weight of molten iron loaded in each molten iron transport vehicle, and the molten iron components (hereinafter referred to as molten iron information). The second step is to store in a second storage means the required weight, required components, and tapping time (hereinafter referred to as tapping information) for multiple converter charges. Furthermore, the third step is to allocate the molten iron from the molten iron transport vehicles to the converter charge based on the molten iron information and the tapping information so that the inventory amount is below a predetermined value or within a predetermined range. Furthermore, as a fourth step, there is a step of determining the component amount of the molten iron in the molten iron transport vehicle assigned to the converter charge after pretreatment at the pretreatment facility, based on the tapping information.
[0004] Thus, in the blast furnace converter process, conventionally, a method has been proposed for determining the hot metal composition, etc. according to the melting charge of the converter. However, for each melting charge of the converter, the required CO ２ emission per unit is used to determine the blending ratio of hot metal and cold iron source, so as to produce different steel products with different CO ２ emissions. There was no steelmaking method available. Also, since the CO ２ emission cannot be re-analyzed midway like a component, it is necessary to trace the change in CO ２ emission from the initial stage of hot metal production to the progress of the process. Furthermore, accurate CO ２ emissions cannot be obtained only by combining processes, selecting raw materials, and adjusting usage amounts.
[0005] On the other hand, Patent Documents 2 and 3 disclose a carbon dioxide emission calculation system, its method, and a recording medium for its program, etc., which are used in the production of steel products in general. The operation of each calculation system is as follows.
[0006] The carbon dioxide emission calculation system disclosed in Patent Document 2 has eight operations. As the first operation, in the carbon dioxide emission calculation device, the raw material CO ２ emission total amount regarding the raw materials for the production of the target product of the target type is obtained by the raw material emission amount calculation unit of the control processing unit. As the second operation, for each of the plurality of facilities where auxiliary equipment is used, the CO ２ emission allocation amount regarding the facility where the auxiliary equipment is used is obtained by the emission allocation amount calculation unit of the control processing unit. As the third operation, for each of the plurality of main facilities corresponding to each of the plurality of processes used for the production of the target product of the target type, the second unit CO ２ emission amount per unit in the main facility is obtained by the main facility unit emission amount calculation unit of the control processing unit. As the fourth operation, for each of the plurality of main facilities corresponding to each of the plurality of processes used for the production of the target product of the target type, the process CO ２The emission amount is determined. In the fifth step, the auxiliary processing emission calculation unit of the control processing unit calculates the auxiliary processing CO2 related to a predetermined process for the target product of the target type. ２ The total amount of emissions is determined. In the sixth step, the first and second residual emission calculation units of the control processing unit calculate the fourth unit CO2 per unit product in the residual emission source. ２ The emissions are determined, and the second residual CO2 emission source for the target product of the target type is calculated. ２ The total amount of emissions is determined. In the seventh step, the target product emission calculation unit of the control processing unit calculates the target product CO2 for the target product of the target type. ２ The total amount of emissions is determined. Then, as the eighth step, the control unit of the control processing unit outputs the calculation results of each calculation unit from the output unit, and the process ends.
[0007] Furthermore, the carbon dioxide emission calculation system disclosed in Patent Document 3 has six steps in its operation. In the first step, the carbon dioxide emission calculation device first determines the total factory emissions using the total factory emission calculation unit of the control processing unit. In the second step, the equipment unit emission calculation unit of the total product emission calculation unit of the control processing unit determines the first unit CO2 per unit for each of the multiple pieces of equipment corresponding to each of the multiple processes used in the manufacture of products completed in a predetermined period. ２ The emission amount is determined. In the third step, the equipment emission calculation unit in the total product emission calculation unit calculates the equipment CO2 emissions for each of the multiple pieces of equipment corresponding to multiple processes used in the manufacture of the products completed during the predetermined period. ２ The emissions are determined. In the fourth step, the total amount calculation unit in the total product emissions calculation unit calculates the CO2 emissions for each of the multiple pieces of equipment corresponding to the multiple processes used in the manufacture of the product completed during the predetermined period, as determined by the equipment emissions calculation unit. ２ The total amount of emissions is determined as the total product emissions. In the fifth step, the allocation calculation unit of the control processing unit calculates the difference between the total factory emissions obtained in the first step and the total product emissions obtained in the fourth step, and the obtained difference is used to calculate the CO2 emissions for each type of product. ２The amount allocated to each product type is determined based on the emission ratio, and then allocated to each product type. In the sixth step, the control unit of the control processing unit outputs each calculation result from the output unit, and the process ends.
[0008] As described above, the carbon dioxide emission calculation systems disclosed in Patent Documents 2 and 3 are not specific to the blast furnace converter method in the manufacture of steel products, but rather simply the CO2 emissions of the target product. ２ This system is for calculating the total amount of emissions, the total amount of emissions from a product, and the allocation amount for each product type. In other words, these carbon dioxide emission calculation systems simply calculate the CO2 emissions of the target product. ２ It is configured solely to calculate the total amount of emissions and the allocated amount for each type of product, and to output the calculation results to the output unit. Then, according to the total amount and allocated amount (or by working backward from there), CO ２ The system does not include a mechanism for combining raw materials with different emission intensities according to a predetermined mixing ratio, determining that mixing ratio, or issuing mixing instructions based on such a ratio. In other words, the above carbon dioxide emission calculation system alone cannot, for example, calculate the required CO2 emissions set for each melting charge of the converter. ２ By determining the mixing ratio of molten iron and cold iron source according to the emission intensity, CO ２ It is not possible to manufacture different steel products with varying emission levels.
[0009] Japanese Patent Publication No. 2010-138432, International Publication No. 2024 / 116584, International Publication No. 2024 / 185267
[0010] Thus, the method described in Patent Document 1 is CO ２ CO emissions are not a required characteristic. ２ It is not possible to manufacture steel products with different CO emissions. ２ Considering that emissions are increasingly being included in the required characteristics, in an integrated steelworks with blast furnaces and converters, a melting furnace should be installed in addition to the blast furnace, and the required CO2 emissions should be set for each melting charge of the converter. ２ A system is needed that can produce different steel products according to their emission intensity. For example, low CO2 ２ Using molten iron to reduce CO ２ Low CO2 levels are required when manufacturing steel products.２ Molten iron, ordered low CO ２ A mechanism is needed to allocate to the charge. Furthermore, in the calculation system described in Patent Documents 2 and 3, ２ Although emissions can be calculated, based on that, CO ２ It is not intended to produce different steel products with varying emission levels. To solve the problems described above in the prior art, the present invention relates to CO2 emissions in the steelmaking process. ２ By tracing emissions, CO ２ The primary objective is to provide a converter steelmaking method that can produce steel products with varying emission levels.
[0011] On the other hand, as mentioned above, CO ２ When trying to manufacture different steel products with varying CO2 emissions, ２ While raw materials with emission factors such as reduced iron and scrap are used, the use of reduced iron and scrap may lead to the following drawbacks. Specifically, there are concerns about an increase in phosphorus due to reduced iron, an increase in tramp elements due to scrap, and an increase in nitrogen due to nitrogen absorption in low-C molten metal. For this reason, if only molten iron from electric furnaces using reduced iron and scrap as the main raw materials is used, it may be difficult to manufacture certain types of steel, such as high-purity steel. In order to solve these secondary problems, the present invention has a second objective in addition to the first objective described above: to provide a converter steelmaking method that can produce steel products with different concentrations of impurity elements by tracing the concentration of impurity elements in the molten iron.
[0012] A converter steelmaking method according to the first aspect of the present invention, which advantageously solves the above problems, is characterized by a CO2 ratio per unit mass of molten iron. ２ A converter steelmaking method using multiple melting furnaces with different emission rates, one or more transport containers for transporting molten iron produced in the melting furnaces, and a converter for charging the molten iron and refining it, wherein the melting furnace CO ２ Using the emission intensity identification means, the CO2 emissions from the molten iron for each of the melting furnaces are determined. ２ The first step is to identify the emission intensity, and the CO2 emissions from the molten iron for each identified melting furnace. ２Based on the emission intensity, the required CO2 for each melting charge of the converter is set. ２ The method is characterized by comprising: a second step of determining the mixing ratio of the molten iron and cold iron source for each of the melting furnaces to be charged into the converter, according to the emission rate; and a third step of charging the molten iron and cold iron source for each of the melting furnaces into the converter based on the determined mixing ratio.
[0013] A converter steelmaking method according to a second aspect of the present invention, which advantageously solves the above problems, is characterized in that, based on the converter steelmaking method according to the first aspect, in the first step, the concentration of impurity elements derived from the molten iron for each melting furnace is further specified using impurity element concentration specification means, and in the second step, based on the concentration of impurity elements derived from the molten iron for each melting furnace specified, the mixing ratio of the molten iron for each melting furnace and the cold iron source to be charged into the converter is determined in accordance with the required impurity element concentration set for each melting charge of the converter.
[0014] Furthermore, in the converter steelmaking method according to the first and / or second aspect of the present invention, (a) the CO of each of the molten irons being mixed ２ (b) The CO2 emissions from each of the molten iron sources are determined, and the fourth step further includes a step of mixing the molten iron in the transport container or charging container before charging the molten iron and the cold iron source into the converter, (b) CO2 emissions from each of the molten iron sources being mixed. ２(c) The process further includes a fourth step of mixing the molten iron in the transport container or charging container before charging the molten iron and the cold iron source into the converter, after determining the emission rate, the concentration of the impurity elements derived from each of the molten irons, and the amount of molten iron received from each of the molten irons; (d) The mixing ratio is such that the molten iron from each of the molten irons is 0 to 100% by mass, the total amount of molten iron is 70 to 100% by mass, and the cold iron source is 0 to 30% by mass; (e) The mixing ratio is such that the molten iron from the blast furnace is 50% by mass or less, and the total amount of molten iron from the molten irons from the molten irons other than the blast furnace is 50 to 100% by mass; (f) CO2 emissions from the refining in the converter to the shipment of steel products. ２ Identify the emissions, and the CO2 ２ CO2 per unit mass of product based on emissions ２ Predict the emission intensity and adjust the required CO2 so that the predicted value becomes the target value. ２ A more preferable solution would be to set an emission intensity, and (g) identify the amount of impurity elements mixed in from the refining in the converter to the shipment of the steel product, predict the concentration of impurity elements per unit mass of product based on the amount of impurity elements mixed in, and set the required concentration of impurity elements so that the predicted value becomes the target value.
[0015] According to the present invention, high CO2 produced in a blast furnace ２ Low CO2 produced in molten iron and blast furnaces other than blast furnaces ２ In a steel mill where molten iron is mixed with CO ２ It is possible to manufacture steel products with different emission levels. For example, low CO2 emissions. ２ The CO2 required for the melting charge that requires molten iron. ２ Depending on the emission intensity, the low CO ２ By incorporating a function to calculate the amount of molten iron used, one charge in the converter can be reduced to low CO2 levels. ２ Only molten iron is used, low CO2 ２ It can manufacture steel products. Also, it produces low CO2. ２ Not only steel products, but also CO ２ By using one or more types of molten iron with different emission intensity, the CO2 emissions required by other standards can be met.２ It is also possible to manufacture steel products according to the emission intensity. That is, according to the first embodiment of the present invention, within the same steelworks, the required CO2 per converter charge unit can be met. ２ The emission intensity can be switched. This allows for, for example, low CO2 emissions. ２ It also becomes possible to manufacture the product and regular products in parallel on the same day. Therefore, CO2 for each customer ２ This enables flexible product differentiation to meet emission requirements.
[0016] Furthermore, according to the second aspect of the present invention, in addition to the effects brought about by the first aspect, it is expected that the increase of impurity elements in steel products can be suppressed by further identifying and controlling the concentration of impurity elements originating from molten iron in each melting furnace. This will reduce CO ２ In addition to controlling emissions, it becomes possible to control the composition of steel products, enabling compliance with a wide variety of quality standards. In other words, it becomes possible to manufacture specific types of steel, and quality constraints can be eased.
[0017] This is a schematic diagram illustrating the converter steelmaking method according to the first embodiment of the present invention. This is a flowchart illustrating the converter steelmaking method according to the above embodiment. This is a schematic diagram illustrating the embodiments of the first group of embodiments in the present invention. This is a schematic diagram illustrating the converter steelmaking method according to the second embodiment of the present invention. This is a flowchart illustrating the converter steelmaking method according to the above embodiment. This is a schematic diagram illustrating the embodiments of the second group of embodiments in the present invention. This is a graph showing the relationship between the nitrogen concentration achieved after processing in the converter-secondary refining and the carbon concentration in the converter mixture.
[0018] The embodiments of the present invention will be described in detail below. The following embodiments are illustrative of equipment and methods for realizing the technical idea of the present invention, and do not limit the configuration to those described below. That is, the technical idea of the present invention can be modified in various ways within the technical scope described in the claims.
[0019] [First Embodiment] The converter steelmaking method according to the first embodiment of the present invention will be described in detail below with reference to the figures. The converter steelmaking method of this embodiment uses CO per unit mass of molten iron. ２This is a converter steelmaking method that uses at least multiple melting furnaces with different emission rates, one or more transport containers for transporting the molten iron produced in the melting furnaces, and a converter for charging the molten iron and refining it. Examples of the multiple melting furnaces include blast furnaces, cupolas, arc melting furnaces, and induction melting furnaces, and two or more of these are used. Examples of blast furnaces include conventional large blast furnaces (BF) and mini blast furnaces (MBF). Examples of cupolas include conventional cupola furnaces and various other types. Examples of arc melting furnaces include submerged electric furnaces (SAF) and electric arc furnaces (EAF). Examples of induction melting furnaces include induction heating (IH) type induction melting furnaces. All of these melting furnaces have different CO emissions per unit mass of molten iron. ２ It has an emission intensity. Examples of transport containers include torpedo cars and molten iron scalding pans, and it is also possible to use a combination of different types of transport containers. As for the converter, for example, a conventional one capable of converter refining is used.
[0020] Figure 1 is a schematic diagram showing an example of the converter steelmaking method according to this embodiment. In the example shown in Figure 1, CO ２ This scenario assumes a steelworks equipped with multiple melting furnaces 1 with different emission rates, including a blast furnace, a cupola, an arc melting furnace, and an induction melting furnace. Specifically, as shown in Figure 1, six melting furnaces 1 are used: blast furnace BF1, blast furnace BF2, cupola CF, submerged electric furnace (SAF), induction melting furnace IF1, and induction melting furnace IF2. Five transport containers 2, designated A to E, are provided for these melting furnaces 1. Furthermore, a converter 3 is provided for smelting. A cold iron source input means 4 is provided for inputting the cold iron source Sc into the converter 3. A charging pot (not shown) may be optionally used for the molten metal mixing process described later. In Figure 1, the converter's CO2 requirement... ２The arrows other than the white arrows, which represent a series of steps including determining the mixing ratio (S3) according to the discharge rate (S1) and issuing mixing instructions (S4) based on the determined mixing ratio, all exemplify the flow of steps such as receiving molten metal into the transport container 2 and charging it into the converter 3 based on the mixing instructions. It is preferable to also have control means 5 such as a calculation device for performing such operations.
[0021] Here, in a steelmaking process with a highly productive blast furnace, CO ２ To produce different steel products with varying emissions, the following elements are considered necessary. Specifically, the first element is molten iron obtained by dissolving reduced iron, etc., which emits less CO than blast furnace pig iron. ２ A low-emission molten iron is required. Furthermore, as a second factor, the CO emissions from the molten iron in each furnace 1 are also important. ２ A means of identifying emission intensity is necessary. Furthermore, as a third element, the required CO2 emissions per melting charge in the converter are needed. ２ A mechanism is needed to determine the mixing ratio of various molten iron and cold iron sources based on the emission intensity. In addition, as a fourth element, the CO2 emissions during the steelmaking process when the molten iron is mixed in a transport container 2 or a charging pot as a charging container. ２ A mechanism is needed to trace changes in emission intensity. The converter steelmaking method according to this embodiment reflects these first to fourth elements. As a result, multiple CO2 requirements can be met. ２ Emission intensity (e.g., 0.6, 0.8, 1.0 T-CO2) ２ The CO2 ratio (T-Fe) can be simultaneously met within the same operational plan. In other words, it becomes possible to switch production in short cycles, which was previously difficult. Therefore, CO2 ratio can be set at the planning stage according to demand fluctuations and customer specifications. ２ This allows for the implementation of operations that actively differentiate the production of steel products with different emission levels.
[0022] The converter steelmaking method of this embodiment, which focuses on the above elements, mainly includes the following first to third steps. As the first step, a molten furnace CO ２ Using the emission intensity identification means, the CO2 emissions from the molten iron for each of the melting furnaces are determined. ２ A step is provided to identify the emission intensity. As a second step, the CO2 emissions from the molten iron for each identified melting furnace are determined. ２Based on the emission rate, the required CO set for each melting charge of the converter ２ A step of determining the blending ratio of the molten iron and the cold iron source for each melting furnace to be charged into the converter according to the emission rate is provided. As a third step, a step of charging the molten iron and the cold iron source for each melting furnace into the converter based on the determined blending ratio is provided. Each step will be described in detail in the following paragraphs.
[0023] [First Step] In the first step, CO in the melting furnace ２ Using the emission rate specifying means for each melting furnace, the CO ２ emission rate (T-CO ２ / T-Fe) per unit mass of molten iron for each melting furnace is specified. Here, the CO ２ emission rate per unit mass of molten iron refers to, for example, the total mass of CO ２ emitted until 1 t of molten iron is produced and the mass of all C in 1 t of molten iron converted to CO ２ . In this step, for example, an arithmetic unit 5 or the like as the emission rate specifying means for the melting furnace CO ２ is used to calculate and grasp in advance the CO ２ emission rate of molten iron obtained from blast furnaces, cupolas, arc melting furnaces, induction melting furnaces, etc. As the arithmetic unit 5, a software or hardware-based system, etc. can be mentioned, and a general arithmetic unit 5 capable of performing operations such as logical operations can be used. Also, when the arithmetic unit 5 is hardware-based, a plurality of arithmetic units 5 connected communicably may be used.
[0024] In calculating the CO ２ emission rate of molten iron in each melting furnace, the CO ２ load of the raw materials themselves used is also taken into account. For example, when the melting furnace is a blast furnace, specifically, the CO ２ load when using ore and coke as raw materials is considered, and the CO ２ emission rate of molten iron is specified. Also, for example, when the melting furnace is a cupola, specifically, the CO ２ load when using scrap and carbonaceous materials as raw materials is considered, and the CO ２Identify the CO2 emission intensity. Furthermore, for example, if the melting furnace is an arc melting furnace or an induction melting furnace, the CO2 emissions from the raw materials used in each furnace, such as reduced iron (HBI), scrap, carbon, and pig iron, must also be identified. ２ Taking the load into account, the CO2 of molten iron in each melting furnace ２ Identify the CO2 emissions per unit area. Here, calculate the CO2 emissions from each furnace, considering both cases: using raw materials obtained through recycling within the same steelworks and using raw materials obtained from external sources. ２ Emissions per unit may fluctuate. Also, when using electric furnaces such as arc furnaces, the CO2 emissions from electricity may vary. ２ We will also take the coefficients into consideration.
[0025] Here, molten iron from furnaces other than blast furnaces is all CO2 higher than blast furnace pig iron. ２ Because it is molten iron with low emissions, CO ２ This fulfills the first element above for producing different steel products with varying emission levels. In addition, the calculation unit 5, which is the molten furnace CO ２ The means of determining emission intensity is, in other words, the CO2 emissions from molten iron in each melting furnace. ２ A means is established to identify the emission intensity, ２ This will satisfy the second factor mentioned above, which is necessary for producing different types of steel products with varying emission levels.
[0026] [Second step] In the second step, the CO of the molten iron from each of the identified melting furnaces ２ Based on the emission intensity, the required CO2 for each melting charge of the converter is set. ２ In accordance with the emission rate per unit, the mixing ratio (mass%) of molten iron and cold iron source for each melting furnace to be charged into the converter is determined. In this step, the mixing ratio of molten iron and cold iron source is determined using a computing device 5 or the like. Similar to the first step, in this step, a general computing device 5 capable of performing calculations such as logical operations using software or hardware-based systems can be used as the computing device 5. Also, similar to the above, if the computing device 5 is hardware-based, multiple computing devices 5 connected in a communicative manner may be used. Furthermore, the CO of the molten iron ２For the purpose of adjusting the emission intensity, molten iron may be used not only as a single type, but also as a combination of two or more types obtained from different melting furnaces, and two or more types of molten iron can be used in the form of a blended molten metal, as described later.
[0027] Specifically, for example, the required CO2 set for each melting charge of the converter. ２ Emissions intensity (T-CO2) ２ Depending on the T-Fe ratio, the aforementioned blending ratio is set so that the molten iron from each furnace is 0 to 100% by mass, the total molten iron is 70 to 100% by mass, and the cold iron source is 0 to 30% by mass. Alternatively, the blending ratio of the cold iron source may be kept the same, the molten iron from the blast furnace may be 50% by mass or less, and the total molten iron from furnaces other than the blast furnace may be 50 to 100% by mass. Here, scrap metal can be used as the cold iron source, and the addition of the cold iron source is CO ２ The aim is to reduce and adjust the emission intensity. From this perspective, cold iron sources such as scrap added to the converter also contribute to CO emissions. ２ It can be said that this is a factor for differentiating the production of steel products with different emission levels. In this embodiment, when scrap is used as a cold iron source, the carbon concentration of the scrap itself is CO ２ Because it becomes a load, the CO2 of the scrap itself ２ The load can be considered to be zero. In this way, each required level of CO2 ２ Various CO2 requirements depending on emissions ２ The mixing ratio of various molten iron and cold iron sources can be determined according to the emission intensity.
[0028] Here, the second step in this embodiment is to determine the required CO2 for each melting charge of the converter. ２ Because it is based on a system that determines the mixing ratio of various molten iron and cold iron sources from the emission intensity, CO ２ This will satisfy the third element mentioned above, which is necessary for producing different steel products with varying emission levels.
[0029] [Third Step] In the third step, the molten iron and cold iron source for each melting furnace are charged into the converter based on the determined mixing ratio. Specifically, first, based on the mixing ratio, a mixing instruction is given to charge a predetermined amount of one or more types of molten iron into the one or two or more transport containers. When two or more types of molten iron are used, the converter steelmaking method of this embodiment uses CO2 for each of the molten irons to be mixed. ２ The process may further include a step (the fourth step) in which the molten iron is mixed in the transport container or charging container before charging the molten iron and cold iron source into the converter, after understanding the emission intensity and the amount of molten iron received. The instruction for this mixing step may be included as part of the mixing instructions. That is, when two or more types of molten iron are used, the two or more types of molten iron may be combined in the same transport container as a mixed molten metal, or they may be charged into separate transport containers and then charged into a charging container such as a charging pot, and the mixing is performed in the charging container. Then, the predetermined CO ２ If it is necessary to add a cold iron source when charging the converter in order to meet the emission intensity requirements, a mixing instruction is issued to add a predetermined amount of cold iron source according to the mixing ratio calculated in the second step. Such a mixing instruction for adding a cold iron source may be included as part of the mixing instruction for the molten iron, or it may be a separate mixing instruction. That is, these mixing instructions may be configured as a single, combined instruction, or as a group of separate instructions.
[0030] Thus, in this embodiment, when blending is performed as necessary, the CO2 of each molten iron being blended ２ Because it can be executed while monitoring the emission intensity and the amount of hot water received, CO2 emissions during the steelmaking process ２ It becomes possible to trace changes in emission intensity. That is, CO ２ This will satisfy the fourth element mentioned above, which is necessary for producing different steel products with varying emission levels.
[0031] Figure 2 is a flowchart illustrating the converter steelmaking method according to this embodiment. First, the required CO2 for each melting charge of the converter... ２ Set the emission intensity (S1). ２The emission intensity is the CO2, which is the general definition of green steel. ２ Emission intensity ≤ 0.5 or 0.6 T-CO ２ / T-Fe as well as CO ２ Emission intensity ≤ 0.8 T-CO ２ / T-Fe and CO ２ Emission intensity ≤ 1.0 T-CO ２ The standard may also be such as / T-Fe. The converter steelmaking method according to this embodiment can produce steel products according to each of these standards. Next, the molten furnace CO ２ Using emission intensity identification methods, the CO2 emissions from molten iron in each furnace are determined. ２ Identify the emission intensity (S2). As mentioned above, the CO emissions from molten iron in each furnace. ２ In determining the emission intensity, the CO2 of the raw materials themselves is used. ２ CO2 from load and power ２ Coefficients and other factors will also be taken into consideration. And the CO of each of these identified melting furnaces ２ The emission intensity is a value that needs to be known in advance, and may be stored in a storage device or similar. Next, the set required CO2 ２ CO2 emissions from each melting furnace calculated to meet emission intensity requirements. ２ Based on the emission rate, the mixing ratio of various molten iron and cold iron sources is determined (S3). Based on this mixing ratio, mixing instructions are issued, such as an instruction to charge one or more of the relevant types of molten iron in predetermined amounts (predetermined receiving amounts) into one or more transport containers, an instruction to mix the molten iron from each type in the same transport container, an instruction to mix the molten iron from each type from the transport container in a charging container such as a charging pot, and / or an instruction to add a predetermined amount of cold iron source (S4). As described above, these mixing instructions may be configured as a single, combined instruction or as multiple individual instructions. Based on these instructions, a predetermined amount of the relevant type of molten iron and, if necessary, a predetermined amount of cold iron source are charged into the converter (S5). Here, the CO2 requirement for each melting charge of the converter is... ２ After setting the emission intensity (S1), the CO emissions from molten iron for each melting furnace are calculated. ２ Although emission intensity is specified (S2), for example, the CO emissions from molten iron in each melting furnace ２CO2 emissions after specifying emission intensity (S2) ２ The system may also be configured to set the emission intensity (S1). Furthermore, the required CO2 emissions for each melting charge of the converter may also be configured. ２ The emission intensity is the CO2 emissions from the resulting steel products. ２ It may also be determined based on emissions.
[0032] In this embodiment, the CO2 from smelting in the converter to the shipment of steel products ２ Identify the emissions, and the CO2 ２ CO2 per unit mass of product based on emissions ２ Predict the emission intensity and adjust the required CO2 so that the predicted value becomes the target value. ２ Emissions intensity (T-CO2) ２ You can also set ( / T-Fe). This allows for higher standards of CO2 emissions from steel products. ２ This will allow us to control emissions. Here, CO2 per unit mass of product ２ Emission intensity refers to, for example, the amount of CO2 emitted when producing 1 ton of steel products from the melting of molten iron to the shipment of the steel products. ２ The mass and all of the carbon in 1 ton of steel products are CO ２ This refers to the sum of the converted masses.
[0033] As described above, the converter steelmaking method according to this embodiment has a CO2 content per unit mass of molten iron. ２ In a steel mill where melting furnaces with different emission intensity levels are mixed, the required CO2 emissions are set for each melting charge of the converter. ２ Depending on the emission intensity, different CO2 ２ It is possible to easily produce steel products of different levels. Furthermore, from the standpoint of mass production and cost, it is preferable that the above-mentioned types of melting furnaces include a blast furnace. The productivity of arc melting furnaces and induction melting furnaces does not match the production volume of converters in a typical steel mill, so a large amount of blast furnace pig iron is usually used.
[0034] On the other hand, naturally, CO ２ If we focus solely on controlling emissions, low CO2 ２ Converter requirements in accordance with steel product standards CO ２In the instruction system that issues the above blending instructions according to the emission intensity, the blending instructions may also specify the use of molten iron from furnaces other than blast furnaces. This will result in low CO2 emissions. ２ This enables the smooth manufacturing of steel products.
[0035] [Second Embodiment] The converter steelmaking method according to the second embodiment of the present invention will be described in detail below with reference to the figures. The converter steelmaking method of this embodiment is based on the converter steelmaking method according to the first embodiment described above, but differs mainly in the following points. Specifically, in the converter steelmaking method of this embodiment, in the first step, the concentration of impurity elements derived from the molten iron for each melting furnace is further identified using impurity element concentration identification means. In the second step, based on the identified concentration of impurity elements derived from the molten iron for each melting furnace, the mixing ratio of the molten iron for each melting furnace and the cold iron source to be charged into the converter is determined in accordance with the required impurity element concentration set for each melting charge of the converter.
[0036] In this embodiment, the impurity elements refer to trump element, phosphorus, and nitrogen, etc. These impurity elements are generated when using electric furnaces that heavily utilize reduced iron or scrap as raw materials. Specifically, an increase in trump element is due to scrap, an increase in phosphorus is due to reduced iron, and an increase in nitrogen is due to nitrogen absorption in low-C molten metal. For this reason, for example, if only molten iron from an electric furnace is used, it may be difficult to manufacture certain types of steel, such as high-purity steel. Therefore, in this embodiment, it is preferable to use molten iron from an electric furnace in combination with molten iron from a blast furnace with a low concentration of the above-mentioned trump element, etc., in a predetermined ratio. This reduces CO ２ This will not only allow for the control of emissions but also the assurance of the quality of steel products. Here, "tramp elements" are assumed to be elements that are difficult to remove in the steelmaking process, such as copper and tin. Furthermore, as shown in the group of inventive examples in the second group of embodiments described later, in certain cases, it may be possible to control impurity elements without using molten iron from a blast furnace.
[0037] In this embodiment, specifying the concentration of impurity elements derived from molten iron in each furnace in the first step means, for example, directly or indirectly by a mechanism described later, specifying the concentration of impurity elements such as copper, tin, and nitrogen derived from each molten iron. Furthermore, the means for specifying the concentration of impurity elements can be the same as that of the calculation device 5 in the first embodiment, and the concentration of impurity elements derived from molten iron from each furnace may be calculated and understood in advance using the same method as in the first embodiment. Moreover, as in the first embodiment, it is conceivable that raw materials obtained through circulation within the same steelworks may be used, or that raw materials obtained from external sources may be used.
[0038] Here, for example, if nitrogen is included in the impurity elements to be controlled, the control of the target nitrogen concentration after treatment (target nitrogen concentration) can be performed based on the mechanism shown in the graph of Figure 7 (hereinafter also referred to as the "mixed carbon concentration identification mechanism"). Figure 7 is a graph showing the relationship between the target nitrogen concentration after treatment (mass ppm) and the converter mixed carbon concentration (mass %) in the converter-secondary refining process. Specifically, in the converter-RH process, the target nitrogen concentration (mass ppm) of the molten steel is mainly influenced by the denitrification that occurs as a side effect of the decarburization reaction in the converter. Therefore, since the mixed carbon concentration greatly affects the target nitrogen concentration, the combination with molten carbon is an important element in molten metal mix design, just like other tramp elements. That is, in this embodiment, first, based on the relationship shown in the graph of Figure 7, the mixed carbon concentration for each molten charge is indirectly identified from the nitrogen concentration, which is the required impurity element concentration set for each molten charge in the converter. Next, based on the identified carbon concentration of each molten iron and cold iron source, the mixing ratio of each molten iron and cold iron source is determined, taking into account the carbon concentration derived from the molten iron and cold iron sources of each furnace. Here, an example of a case where nitrogen is included in the impurity elements to be controlled is when, in addition to nitrogen, copper and tin are also to be controlled, as shown in Table 1 below. In the example shown in Table 1, the molten iron and cold iron sources used are those from the furnace used in the first embodiment. Naturally, even if other impurity elements such as nickel, molybdenum, and chromium are to be controlled, as long as nitrogen is included in the controlled elements, control can be performed using a similar mechanism.
[0039] Note that the component values shown in Table 1 are representative examples, and variations may occur in each component due to operating conditions or measurement errors. Even with compositions that include such variations, the effects achieved by the converter steelmaking method according to this embodiment are maintained. Therefore, the control targets in the converter steelmaking method according to this embodiment are not limited to components having the composition shown in Table 1.
[0040] Furthermore, this embodiment may also include a fourth step in the same manner as in the first embodiment. Specifically, in the fourth step in this embodiment, the CO2 of each of the molten irons being mixed is added.２ The discharge rate, the concentration of impurity elements derived from each of the molten irons, and the amount of molten iron received from each are determined. Based on these assumptions, the molten irons are mixed in the transport container or charging container before charging the molten iron and the cold iron source into the converter.
[0041] Furthermore, in this embodiment as well, as described above, one or more types selected from blast furnaces, cupolas, arc melting furnaces, and induction melting furnaces are used. Moreover, in this embodiment as well, CO2 from smelting in the converter to shipment of steel products is used. ２ Identify the emissions, and the CO2 ２ CO2 per unit mass of product based on emissions ２ Predict the emission intensity and adjust the required CO2 so that the predicted value becomes the target value. ２ The emission intensity can be set. In addition, the amount of impurity elements mixed in from the refining in the converter to the shipment of the steel product can be identified, the concentration of impurity elements per unit mass of product can be predicted based on the amount of impurity elements mixed in, and the required concentration of impurity elements can be set so that the predicted value becomes the target value.
[0042] Figure 4 is a schematic diagram showing an example of the converter steelmaking method according to this embodiment. In Figure 4, components that overlap with those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted. In the figure, the required CO2 of the converter... ２ The white arrows indicate a series of steps, from determining the blending ratio according to the emission intensity and required impurity element concentration (S11) (S13) to issuing a blending instruction (S14) based on the determined blending ratio. Similar to the first embodiment, arrows other than these white arrows exemplify the flow of steps such as receiving molten metal into the transport container 2 and charging into the converter 3 based on the blending instruction. Figure 5 is a flowchart explaining the converter steelmaking method according to this embodiment. This flowchart differs from the flowchart of the converter steelmaking method according to the first embodiment in the following respects. First, the required CO2 for each melting charge of the converter... ２ The emission intensity and the required impurity element concentration for each melting charge of the converter are set in (S11). Then, the CO of the molten iron for each melting furnace ２The emission intensity and the concentration of impurity elements derived from molten iron for each melting furnace are specified in (S12). In addition, (S13), (S14), and (S15) shown in the flowchart of Figure 5 are substantially the same as (S3), (S4), and (S5) in the corresponding flowchart of the first embodiment.
[0043] As described above, the converter steelmaking method according to this embodiment is CO ２ While keeping emission control in mind, this method also addresses the increase in impurity elements generated when using electric furnaces that heavily utilize reduced iron and scrap as raw materials. In other words, according to the converter steelmaking method of this embodiment, CO ２ In addition to controlling emissions, it also becomes possible to manufacture specific types of steel, such as high-purity steel, thus easing quality constraints. Furthermore, in this embodiment, the control of impurity elements may be limited to the control of specific impurity elements, for example, control targeting only the increase in phosphorus concentration, or control targeting the increase in the concentrations of multiple types of impurity elements.
[0044] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.
[0045] [First Group of Embodiments] Figure 3 is a schematic diagram illustrating the embodiments of the first group of embodiments in the present invention. The first group of embodiments corresponds to the converter steelmaking method according to the first embodiment described above, and consists of Invention Example 1-1, Invention Example 1-2, and Invention Example 1-3. In the embodiment shown in Figure 3, two blast furnaces (BF1 and BF2), a cupola CF, a submerged electric furnace (SAF), and two induction melting furnaces (IF1 and IF2) were used as the melting furnace 1. The raw materials for each melting furnace 1 are as follows: Blast furnace BF1 used ore and coke as raw materials. Blast furnace BF2 used the same raw materials as blast furnace BF1, plus 10% HBI. Cupola CF used scrap and carbon as raw materials. Submerged electric furnace SAF used HBI and carbon as raw materials. Induction melting furnace IF1 used pig iron as raw material. In the induction melting furnace IF2, scrap and carbon materials were used as raw materials. ２For adjusting the discharge rate, scrap was used as the cold iron source (Sc) added to the converter along with the molten iron. Five transport containers, designated A through E, were used as transport containers 2. A standard converter capable of converter refining was used as the converter 3. In addition, a charging pot (not shown), which is a charging container for mixing the molten metal, was used as needed.
[0046] In the first group of embodiments of the present invention, there are cases in which raw materials obtained through circulation within the same steelworks (hereinafter also referred to as internal raw materials) are used and / or raw materials obtained from outside through import, etc. (hereinafter also referred to as external raw materials). In the melting furnace 1 in Figure 3, the CO2 for each melting furnace is located to the right of each melting furnace. ２ Emissions intensity 6 (T-CO2) ２ The CO2 ratio (T-Fe, simply written as T / T in Figure 3) is shown in two separate lines. ２ Of the emission intensity values, the upper value is the CO2 value when using only internal raw materials, regardless of the type of raw material. ２ This represents the emission intensity. On the other hand, the value in the lower row represents the CO2 emissions from the external raw materials when those external raw materials are used. ２ Emission intensity is shown in the upper section CO ２ CO2 obtained by cumulatively adding it to the emission intensity ２ This represents the emission intensity. Here, CO2 related to external raw materials is shown. ２ Emission intensity refers to, for example, the amount of CO2 emitted during the production of raw materials obtained through imports, etc. ２ Examples include emission intensity. Naturally, CO2 emissions overseas. ２ If no CO is generated, even if it is an external raw material, CO related to the external raw material ２ The emission intensity is 0. Furthermore, the CO2 emissions from the scrap used in the cupola CF and induction melting furnace IF2 are also 0. ２ The load is 0 for each.
[0047] Also, domestic power CO2 ２ The coefficient is 0.08 kg / kWh, and the CO2 emissions from overseas power plants. ２ While the coefficient is 0.07 kg / kWh, in the first example group, domestic power generation CO ２A coefficient of 0.08 kg / kWh was used. Furthermore, in the following, the reduction of external raw materials, such as reduced iron from overseas, is assumed to be carried out by liquefied natural gas (LNG). On the other hand, the reduction of internal raw materials, such as reduced iron, is assumed to be carried out by hydrogen reduction. ２ The load addition is expected to be 0. And, Invention Example 1-1, Invention Example 1-2, and Invention Example 1-3, which constitute the first group of embodiments, are each based on the following three criteria (required CO per melting charge) ２ This is based on emission intensity.
[0048] (Example 1-1 of the invention) In Example 1-1 of the invention, the required CO2 per melting charge in the converter ２ Emission intensity of 0.6 T-CO ２ The system was set to / T-Fe or lower for operation.
[0049] In Invention Example 1-1, when internal and / or external raw materials are used, as described above, first, the required CO for each melting charge in the converter ２ Emission intensity of 0.6 T-CO ２ The value was set to / T-Fe or less (S1). Next, the CO2 was used in the melting furnace. ２ CO2 emissions from each melting furnace using emission intensity identification methods ２ The emission intensity 6 was identified, and the values shown on the right side of each smelting furnace in Figure 3 were obtained (S2). Here, 0.6T-CO ２ In accordance with the standard of / T-Fe or less, the CO of each identified melting furnace ２ Based on the emission intensity, the mixing ratios of various molten iron and cold iron sources were determined (S3). Specifically, it was decided to mix 68% by mass of molten iron from the IF1 furnace using external raw materials, 17% by mass of molten iron from the BF1 furnace using external raw materials, and 15% by mass of scrap, which is the cold iron source. Based on these mixing ratios, the mixing instruction was to charge 204 tons of molten iron from the IF1 furnace and 51 tons of molten iron from the BF1 furnace into the same transport container and to mix the molten iron in the transport container. Similarly, the mixing instruction was to add 45 tons of scrap (S4). Based on these instructions, the predetermined amounts of the corresponding types of molten iron and the predetermined amounts of scrap were charged into the converter (S5).
[0050] (Example 1-2 of the invention) In Example 1-2 of the invention, the required CO2 per melting charge in the converter ２ Emission intensity of 0.8 T-CO ２ The system was set to / T-Fe or lower for operation.
[0051] In Invention Example 1-2, when internal and / or external raw materials are used, as described above, first, the required CO for each melting charge in the converter ２ Emission intensity of 0.8 T-CO ２ The value was set to / T-Fe or less (S1). Next, the CO2 was used in the melting furnace. ２ CO2 emissions from each melting furnace using emission intensity identification methods ２ The emission intensity 6 was identified, and the values shown on the right side of each smelting furnace in Figure 3 were obtained (S2). Here, 0.8T-CO ２ In accordance with the standard of / T-Fe or less, the CO of each identified melting furnace ２ Based on the emission intensity, the mixing ratios of various molten iron and cold iron sources were determined (S3). Specifically, it was decided to mix 30% by mass of molten iron from an IF1 furnace using external raw materials, 30% by mass of molten iron from an SAF furnace using external raw materials, 25% of molten iron from a BF1 furnace using external raw materials, and 15% by mass of scrap, which is the cold iron source. Based on these mixing ratios, the mixing instruction was to charge 90 tons of molten iron from an IF1 furnace, 90 tons of molten iron from an SAF furnace, and 75 tons of molten iron from a BF1 furnace using external raw materials into the same transport container and to mix the molten iron in the transport container. Similarly, the mixing instruction was to add 45 tons of scrap (S4). Based on these instructions, the specified amounts of the corresponding types of molten iron and the specified amounts of scrap were charged into the converter (S5).
[0052] (Example 1-3 of the invention) In Example 1-3 of the invention, the required CO2 per melting charge in the converter ２ Emission intensity of 1.0 T-CO ２ The system was set to / T-Fe or lower for operation.
[0053] In Invention Example 1-3, when internal and / or external raw materials are used, as described above, first, the required CO for each melting charge in the converter ２ Emission intensity of 1.0 T-CO ２The value was set to / T-Fe or less (S1). Next, the CO2 was used in the melting furnace. ２ CO2 emissions from each melting furnace using emission intensity identification methods ２ The emission intensity 6 was identified, and the values shown on the right side of each smelting furnace in Figure 3 were obtained (S2). Here, 1.0 T-CO ２ In accordance with the standard of / T-Fe or less, the CO of each identified melting furnace ２ Based on the emission intensity, the mixing ratios of various molten iron and cold iron sources were determined (S3). Specifically, it was decided to mix 40% by mass of molten iron from a BF1 furnace using external raw materials, 45% by mass of molten iron from an IF1 furnace using external raw materials, and 15% by mass of scrap, which is the cold iron source. Based on these mixing ratios, the mixing instruction was to charge 120 tons of molten iron from the BF1 furnace and 135 tons of molten iron from the IF1 furnace into the same transport container and to mix the molten metals in the transport container. Similarly, the mixing instruction was to add 45 tons of scrap (S4). Based on these instructions, the specified amounts of the corresponding types of molten iron and the specified amounts of scrap were charged into the converter (S5).
[0054] [Second Group of Embodiments] Figure 6 is a schematic diagram illustrating the embodiments of the second group of embodiments in the present invention. The second group of embodiments corresponds to the converter steelmaking method according to the second embodiment described above and consists of an inventive example group and a comparative example group. Specifically, the operations shown in Inventive Example 2-1, Inventive Example 2-2, and Inventive Example 2-3 were performed as inventive examples. The operations shown in Comparative Example 2-1, Comparative Example 2-2, and Comparative Example 2-3 were performed as corresponding comparative examples. In the embodiments shown in Figure 6, the same elements as those in the first group of embodiments were adopted except for the points described below, and the raw materials and their formulations for each melting furnace were also the same as those in the first group of embodiments. Therefore, in Figure 6, the same reference numerals are used for components that overlap with those in the first group of embodiments, and their descriptions are omitted. As described in the second embodiment described above, in the second group of embodiments, CO ２In addition to controlling the amount of emissions, the concentration of impurity elements is also controlled. Specifically, the impurity elements in the second group of embodiments refer to copper (Cu), tin (Sn), and nitrogen (N), and the increase in the concentration of these impurity elements is the target of control. Furthermore, in all of the second group of embodiments, the total weight of the molten iron or cold iron source charged into the converter was set to 300 tons.
[0055] In addition, in the second group of embodiments, CO was naturally produced in the same manner as in the first group of embodiments. ２ We are also controlling emissions, but in Figure 6, CO2 for each smelting furnace ２ The display of emission intensity has been omitted.
[0056] (Example 2-1 of the invention) In Example 2-1 of the invention, the required CO2 per melting charge in the converter ２ Emission intensity of 0.5 T-CO ２ The operation was carried out with the following settings: / T-Fe or less, required Cu concentration of 0.15 mass% or less, required Sn concentration of 100 mass ppm or less, and required N concentration of 40 mass ppm or less.
[0057] In Invention Example 2-1, first, the required CO2 per melting charge in the converter ２ The emission intensity and the concentrations of various required impurity elements were set as described above (S11). Next, the CO2 in the melting furnace ２ CO2 emissions from each melting furnace using emission intensity identification methods ２ The emission intensity was identified, and in addition, the Cu and Sn concentrations originating from molten iron in each melting furnace were identified using impurity element concentration identification means (S12). Regarding the control of the target nitrogen (N) concentration according to the required N concentration, control was performed based on the above-mentioned carbon blend concentration identification mechanism. Next, the CO2 concentration of each identified melting furnace was determined. ２The mixing ratio of various molten iron and cold iron sources was determined after considering the emission intensity, the Cu and Sn concentrations derived from the molten iron and cold iron sources for each furnace, and the carbon concentration derived from the molten iron and cold iron sources for each furnace (S13). Specifically, it was decided to mix 45% by mass of molten iron from the SAF furnace, 45% by mass of molten iron from the IF2 furnace, and 10% by mass of scrap, which is the cold iron source. Based on this mixing ratio, the mixing instruction was to charge 135 tons of molten iron from the SAF furnace and 135 tons of molten iron from the IF2 furnace into the same transport container and mix the molten metal in the transport container. Similarly, the mixing instruction was to add 30 tons of scrap (S14). Then, based on these instructions, the predetermined amounts of the corresponding types of molten iron and the predetermined amounts of scrap were charged into the converter (S15). As is clear from Table 2 showing the specifications of Invention Example 2-1, the above-mentioned required CO ２ We were able to issue instructions to ensure the formulation met the numerical ranges for emission intensity, required Cu concentration, required Sn concentration, and required N concentration.
[0058] (Example 2-2 of the invention) In Example 2-2 of the invention, the required CO2 per melting charge in the converter ２ Emission intensity of 0.5 T-CO ２ The operation was carried out with the following settings: / T-Fe or less, required Cu concentration of 0.05 mass% or less, required Sn concentration of 50 mass ppm or less, and required N concentration of 30 mass ppm or less.
[0059] In Invention Example 2-2, the operation from (S11) to (S15) was carried out following the same flow as in Invention Example 2-1. Also, as in Invention Example 2-1, the control of the target nitrogen (N) concentration according to the required N concentration was controlled based on the above-described carbon concentration specification mechanism. Specifically, it was decided to blend 80 mass% of molten iron from the SAF furnace, 10 mass% of molten iron from the IF2 furnace, and 10 mass% of scrap, which is the cold iron source. Based on these blending ratios, the blending instruction was given to charge 240 tons of molten iron from the SAF furnace and 30 tons of molten iron from the IF2 furnace into the same transport container and to mix the molten metal in the transport container. Similarly, the blending instruction was given to add 30 tons of scrap. As is clear from Table 3 showing the specifications of Invention Example 2-2, the above-described required CO ２We were able to issue instructions to ensure the formulation met the numerical ranges for emission intensity, required Cu concentration, required Sn concentration, and required N concentration.
[0060] (Example 2-3 of Invention) Example 2-3 of Invention prioritizes the steel grades of Examples 2-1 and 2-2, and assumes operation using the remaining molten metal. In Example 2-3 of Invention, the required CO2 per melting charge in the converter is also considered. ２ The same criteria as in Invention Example 2-2 were adopted for emission intensity, required Cu concentration, required Sn concentration, and required N concentration. In Invention Example 2-3, the operation from (S11) to (S15) was carried out following the same flow as in Invention Examples 2-1 and 2-2. Also, as in Invention Examples 2-1 and 2-2, the control of the target nitrogen (N) concentration according to the required N concentration was controlled based on the above-described carbon concentration specification mechanism. Specifically, it was decided to blend 30 mass% of molten iron from IF1 furnace, 60 mass% of molten iron from IF2 furnace, and 10 mass% of scrap, which is the cold iron source. Based on these blending ratios, the blending instruction was to charge 90 tons of molten iron from IF1 furnace and 180 tons of molten iron from IF2 furnace into the same transport container and to combine the molten metal in the transport container. Similarly, the blending instruction was to add 30 tons of scrap. As is clear from Table 4 showing the specifications of Invention Example 2-3, the required CO2 concentration adopted above was ２ We were able to issue instructions to ensure the formulation met the numerical range for emission intensity. However, the required Cu concentration, required Sn concentration, and required N concentration did not meet the corresponding numerical ranges.
[0061] Generally, the supply rate of molten metal differs for each process, and its temperature gradually decreases, requiring a balance between supply and consumption over a certain period. Therefore, a configuration that calculates the amount of molten metal produced by each process and the required amount of molten metal for each process based on the ordered tapping sequence, and instructs the system to allocate the molten metal from a specific process to a specific charge, is preferable. Furthermore, a function that provides guidance requesting a change in the ordered sequence if the ordered sequence cannot be achieved is even more preferable.
[0062] (Comparative Example 2-1) Comparative Example 2-1 corresponds to Invention Example 2-1, and the required CO2 per melting charge in the converter ２ The same criteria as in Invention Example 2-1 were adopted for the emission intensity, required Cu concentration, required Sn concentration, and required N concentration.
[0063] In Comparative Example 2-1, the operation was carried out in the same manner as in Invention Example 2-1, and the mixing ratio of molten iron and cold iron sources from each melting furnace, their mixing amounts, and the concentration of impurity elements to be controlled are as shown in Table 5, which shows the specifications for Comparative Example 2-1. As is clear from Table 5, it was possible to instruct the mixing to satisfy the standard numerical range for the required Cu concentration, required Sn concentration, and required N concentration. On the other hand, the required CO ２ Regarding emission intensity, it did not meet the standard numerical range.
[0064] (Comparative Example 2-2) Comparative Example 2-2 corresponds to Invention Example 2-2, and the required CO2 per melting charge in the converter. ２ The same criteria as in Invention Example 2-2 were adopted for the emission intensity, required Cu concentration, required Sn concentration, and required N concentration.
[0065] In Comparative Example 2-2, the operation was carried out in the same manner as in Invention Example 2-2, and the mixing ratio of molten iron and cold iron sources from each melting furnace, their mixing amounts, and the concentration of impurity elements to be controlled are as shown in Table 6, which shows the specifications for Comparative Example 2-2. As is clear from Table 6, the required CO ２ Regarding emission intensity, we were able to issue instructions to ensure the formulation met the standard numerical range. However, the required Cu concentration, required Sn concentration, and required N concentration all failed to meet the standard numerical range.
[0066] (Comparative Example 2-3) Comparative Example 2-3 corresponds to Invention Example 2-3, and the required CO2 per melting charge in the converter. ２ The same criteria as in Invention Example 2-3 were adopted for the emission intensity, required Cu concentration, required Sn concentration, and required N concentration.
[0067] In Comparative Example 2-3, the operation was carried out in the same manner as in Invention Example 2-3, and the mixing ratio of molten iron and cold iron sources from each melting furnace, their mixing amounts, and the concentration of impurity elements to be controlled are as shown in Table 7, which shows the specifications for Comparative Example 2-3. As is clear from Table 7, the required CO ２ None of the emission intensity, required Cu concentration, required Sn concentration, or required N concentration met the standard numerical range. In Tables 2 to 7, the component concentrations in the "Total Blend" column are average values that take into account the blending amounts and ratios of each molten iron and cold iron source. Furthermore, regarding nitrogen concentration in these tables, since the nitrogen concentration achieved after subsequent degassing is determined based on the carbon concentration resulting from the converter blending, the nitrogen concentration derived from the molten iron in each furnace is not listed, and the nitrogen concentration is shown only in the "Total Blend" column.
[0068]
[0069]
[0070]
[0071]
[0072]
[0073]
[0074] This invention is CO ２ Because this technology allows for the production of steel products with different emissions and qualities, it can meet the diverse needs of steel product users in fields such as construction, automotive, and energy. Furthermore, the converter steelmaking method according to the present invention can be easily applied to existing steel mill facilities that have blast furnaces, thus enabling low-cost implementation.
[0075] 1. Blast furnaces BF1, BF2: Blast furnace CF: Cupola SAF: Submerged electric furnace (arc melting furnace) IF1, IF2: Induction melting furnace 2. Transport containers (for molten iron) A-E: Transport containers 3. Converter 4. Cold iron source input means Sc: Cold iron source 5. Calculation device (control means) 6. CO (of the blast furnace) ２ Emissions intensity
Claims
1. CO2 per unit mass of molten iron ２ A converter steelmaking method using multiple melting furnaces with different emission rates, one or more transport containers for transporting molten iron produced in the melting furnaces, and a converter for charging the molten iron and refining it, wherein the melting furnace CO ２ Using the emission intensity identification means, the CO2 emissions from the molten iron for each of the melting furnaces are determined. ２ The first step is to identify the emission intensity, and the CO2 emissions from the molten iron for each identified melting furnace. ２ Based on the emission intensity, the required CO2 for each melting charge of the converter is set. ２ A converter steelmaking method characterized by comprising: a second step of determining the mixing ratio of the molten iron and cold iron source for each of the melting furnaces to be charged into the converter according to the discharge rate; and a third step of charging the molten iron and cold iron source for each of the melting furnaces into the converter based on the determined mixing ratio.
2. The converter steelmaking method according to claim 1, characterized in that, in the first step, the concentration of impurity elements derived from the molten iron for each melting furnace is further identified using impurity element concentration identification means, and in the second step, the mixing ratio of the molten iron for each melting furnace and the cold iron source to be charged into the converter is determined based on the identified concentration of impurity elements derived from the molten iron for each melting furnace, in accordance with the required impurity element concentration set for each melting charge of the converter.
3. CO2 from each of the molten irons used in the mixing process. ２ The converter steelmaking method according to claim 1, further comprising a fourth step of knowing the discharge rate and the amount of molten iron received by each of the molten irons, and mixing the molten iron in the transport container or charging container before charging the molten iron and the cold iron source into the converter.
4. CO2 from each of the molten iron being mixed. ２ The converter steelmaking method according to claim 2, further comprising a fourth step of mixing the molten iron in the transport container or charging container before charging the molten iron and the cold iron source into the converter, based on the discharge rate, the concentration of the impurity elements derived from each of the molten irons, and the amount of each of the molten irons received.
5. The converter steelmaking method according to claim 1 or 2, characterized in that two or more types selected from a blast furnace, a cupola, an arc melting furnace, and an induction melting furnace are used as the melting furnace.
6. The converter steelmaking method according to claim 1, characterized in that the mixing ratio is such that the molten iron in each of the melting furnaces is 0 to 100% by mass, the total amount of molten iron is 70 to 100% by mass, and the cold iron source is 0 to 30% by mass.
7. The converter steelmaking method according to claim 6, characterized in that the mixing ratio is 50% by mass or less of the molten iron from the blast furnace and the total amount of the molten iron from the other melting furnaces is 50 to 100% by mass.
8. Identify the CO emissions from the refining in the converter to the shipment of the steel product, and based on the CO ２ emissions, predict the CO emission per unit of product quality, and set the required CO ２ emission per unit so that the predicted value becomes the target value. The converter steelmaking method according to claim 1 or 2, characterized in that ２ the CO emission per unit is set. ２ 9. The converter steelmaking method according to claim 2, characterized in that the amount of impurity elements mixed in from the refining in the converter to the shipment of the steel product is identified, the concentration of impurity elements per unit mass of product is predicted based on the amount of impurity elements mixed in, and the required concentration of impurity elements is set so that the predicted value becomes the target value.