Method for estimating the amount of slag discharged from a converter and a refining method in a converter

Abstract

To estimate a slag removal quantity from a converter at a low cost compared with a case using a scale and at a high precision compared with a case where the slag removal quantity is geometrically obtained.SOLUTION: A converter slag removal quantity estimation method has: an imaging step of imaging a slag flow flowing out from a throat of a converter; an obtainment step of obtaining a volume flow rate or a mass flow rate of the slag flow from the imaged image; and an estimation step of estimating a slag removal quantity from the converter based on the volume flow rate or the mass flow rate.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates to a method for estimating the amount of slag discharged from a converter and a refining method in a converter. [Background technology]

[0002] A known method involves desiliconizing and dephosphorizing molten iron in a converter, then tilting the converter to remove a portion of the slag from the furnace opening while leaving the molten iron inside (intermediate slag removal). Afterward, the converter is returned to an upright position, new refining material is added, and refining continues. This method is economically advantageous due to its lower heat loss compared to a method where the molten iron is discharged from the converter by tilting it after desiliconization and dephosphorization, separating it from the slag, and then decarburizing in a separate converter. However, because it involves the removal of a solvent intermediately, it is not advantageous in terms of slag composition control accuracy. Quantitative determination of the amount of intermediate slag is crucial for improving slag composition control accuracy. Patent documents 1 and 2 describe methods for quantitatively evaluating and estimating the amount of intermediate slag.

[0003] Patent Document 1 discloses a method for estimating the amount of slag discharged from a converter by receiving slag in a slag pan provided on a slag discharge trolley and weighing the amount of slag discharged from the converter (the amount of slag in the slag pan) using a weighing device installed on the floor, and then determining the amount of residual slag in the furnace by subtracting the amount of slag discharged from the estimated amount of slag in the furnace.

[0004] Patent Document 2 discloses a method for adjusting the operating conditions of subsequent processes by determining the amount of residual slag in the furnace from the tilt angle of the converter at the start and end of slag outflow when removing slag from a converter, and subtracting the amount of residual slag from the theoretical amount of slag as the intermediate slag outflow amount. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-41813 [Patent Document 2] Japanese Patent Publication No. 2018-119195 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] By the way, Patent Document 1 uses a weighing scale to determine the amount of intermediate waste, which presents challenges in the installation and maintenance of the weighing scale.

[0007] On the other hand, Patent Document 2 attempts to determine the amount of intermediate slag geometrically, which results in large variations in both the shape of the converter and the state of the slag and metal (molten iron). This leads to the problem of low accuracy in estimating the amount of slag.

[0008] This disclosure is made in view of the above circumstances and aims to provide a method for estimating the amount of slag discharged from a converter at a lower cost than using a weighing scale, and with higher accuracy than geometrically determining the amount of slag discharged. [Means for solving the problem]

[0009] A method for estimating the amount of slag discharged from a converter according to one aspect of the present disclosure comprises: a photography step of photographing the slag flow flowing out from the furnace opening of the converter; a determination step of determining the volumetric flow rate or mass flow rate of the slag flow from the photographed image; and an estimation step of estimating the amount of slag discharged from the converter based on the volumetric flow rate or mass flow rate. [Effects of the Invention]

[0010] According to one aspect of this disclosure, the amount of slag discharged from the converter can be estimated at a lower cost than using a weighing scale, and with higher accuracy than when the amount of slag discharged is determined geometrically. [Brief explanation of the drawing]

[0011] [Figure 1] (A) A side view of the converter according to the embodiment. (B) A side cross-sectional view of the converter shown in Figure 1(A). [Figure 2] This is a side cross-sectional view of the converter showing the state of the molten material remaining inside the tilted converter during slag discharge from the converter in the embodiment. [Figure 3](A) A side sectional view of a converter showing a state in which oxygen is being blown from a lance onto hot metal charged into the converter of the embodiment. (B) A side sectional view of a converter showing a state in which slag is being discharged from the tilted converter. [Figure 4] (A) A side sectional view of a converter showing a state in which oxygen is being blown again from a lance onto the hot metal remaining in the converter in FIG. 3(B). (B) A side sectional view of a converter showing a state in which hot metal is being taken out through a tapping hole from the tilted converter. [Figure 5] A plan view showing the arrangement of a photographing device with respect to the converter when viewed from above the upright converter. [Figure 6] A plan view showing the arrangement of a photographing device with respect to the converter when viewed from the side of the tilted converter. [Figure 7] (A) An enlarged front view showing a state in which slag is flowing out from the mouth of the converter. (B) A cross-sectional view taken along the line 7B-7B of FIG. 7(A), showing the cross-sectional shape at a predetermined position of the slag flow in FIG. 7(A). [Figure 8] A graph showing the relationship between the slag discharge volume by image analysis and the slag discharge volume by geometric calculation. [Figure 9] A diagram showing the configuration of the control device of the embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, an embodiment of the present disclosure will be described.

[0013] First, the converter 20 used in the method for estimating the amount of slag discharged from the converter and the refining method in the converter according to the present embodiment will be described.

[0014] As shown in FIGS. 1 to 9, the converter 20 includes a bottom 20A, a furnace wall 20B, a furnace mouth 20C, and a tapping hole 20D provided in the furnace wall 20B, and the converter 20 is configured to be tilted by a tilting mechanism 24 (see FIG. 9).

[0015] During smelting using the converter 20, molten iron is first charged into the converter 20, and a first refining agent is added to the charged molten iron. The first refining agent is a material (oxide) used to remove phosphorus, silicon, and carbon from the molten iron charged into the converter 20. Examples include calcium oxide (CaO)-based materials such as quicklime and limestone, magnesium oxide (MgO)-based materials, iron oxide (MgO)-based materials, and combinations of one or more of these. As shown in Figure 3(A), a lance 30 is inserted into the converter 20 through the furnace opening 20C. Pressurized gas (e.g., oxygen) is blown from this lance 30 towards the molten iron in the converter 20. This gas blowing stirs the molten iron and the first refining agent in the converter 20, and also oxidizes and removes phosphorus, silicon, and carbon from the molten iron. Next, the lance 30 is moved out of the converter 20, and the converter 20 is tilted (tilted to the right in Figure 3(B)). This tilting of the converter 20 causes slag, which has a higher concentration of phosphorus and silicon than the molten iron, to flow down from the furnace opening 20C into the slag boiler 22 located below the converter 20, while leaving molten iron inside the converter 20, and is discharged (intermediate slag discharge). After intermediate slag discharge, the converter 20 returns to an upright position, as shown in Figure 4(A). Note that the upright position of the converter 20 here refers to the state in which the furnace opening 20C is facing upwards. Then, the second refining material is added to the molten iron inside the converter 20. The second refining material is a material (oxide) used to remove phosphorus and carbon from the molten iron remaining in the converter 20 after intermediate slag removal, and as an example, it may contain the same material as the first refining material. A lance 30 is then inserted into the converter 20 through the furnace opening 20C, and pressurized gas is blown from the lance 30 toward the molten iron in the converter 20, stirring the molten iron and the second refining material within the converter 20, and any remaining phosphorus and carbon in the molten iron is removed. Next, the lance 30 is moved out of the converter 20, and the converter 20 is tilted to the opposite side from when intermediate slag removal is performed (tilted to the left in Figure 4(B)), as shown in Figure 4(B). This tilting of the converter 20 causes the molten steel to flow out from the tapping hole 20D. After the molten steel is removed from the converter 20 (after tapping), the slag remaining in the converter 20, which has low concentrations of phosphorus and silicon and high concentrations of CaO, is reused in the next refining process by being included in the first refining material. Examples of refining methods using such a converter 20 include the MURC method and the double slag method.

[0016] Next, a method for estimating the amount of converter slag using the converter 20 of this embodiment will be described. In the converter slag estimation method of this embodiment, the amount of slag is estimated using image analysis. Specifically, the volume of slag to be discharged is determined from the image of the slag flow during intermediate slag discharge, and the amount of slag discharged (mass of slag discharged) is estimated from that volume.

[0017] [Method for estimating converter slag volume] The method for estimating the amount of converter slag according to this embodiment includes a photography step, a determination step, and an estimation step.

[0018] (Filming process) First, the slag flow SF flowing out of the furnace opening 20C of the converter 20 is photographed. Specifically, as shown in Figure 6, the slag flow SF flowing out (flowing down) from the furnace opening 20C of the converter 20, which has tilted during intermediate slag discharge, toward the slag pot 22 is photographed by the imaging device 40. For example, a CCD camera or a CMOS camera may be used as this imaging device 40. The image information captured by the imaging device 40 is transmitted to the control device 42, which will be described later. The imaging device 40 and the control device 42 are connected by wired or wireless connection.

[0019] As shown in Figure 5, the imaging direction SD of the imaging device 40 for imaging the slug flow SF is inclined with respect to the slag discharge direction of the converter 20 in a plan view. Specifically, when the upright converter 20 is viewed from above, the direction in which the converter 20 tilts during intermediate slag discharge, in other words, the direction in which the slag pan 22 is positioned relative to the converter 20, is the slag discharge direction. Hereafter, the slag discharge direction of the converter 20 will be denoted by the symbol SD.

[0020] The imaging direction SD of the imaging device 40 is inclined at an angle θ with respect to the slag discharge direction DD of the converter 20 in a plan view. This angle θ is preferably set within the range of 0 to 70 degrees, and more preferably within the range of 20 to 50 degrees. In this embodiment, the angle θ is set to 45 degrees, but this disclosure is not limited to this configuration.

[0021] Furthermore, as shown in Figure 6, the imaging direction SD of the imaging device 40 for imaging the slug flow SF is inclined at an angle β with respect to the vertical direction VD when viewed from the side. This angle β is preferably set within the range of 70 to 110 degrees, and more preferably within the range of 80 to 100 degrees. In this embodiment, the imaging direction SD is perpendicular to the vertical direction VD, i.e., angle β is 90 degrees. It is more preferable to set angle β to 90 degrees. When angle β is 90 degrees, the imaging direction SD is aligned with the horizontal direction.

[0022] Furthermore, it is preferable to set the installation height Y of the imaging device 40 to a height that is not affected by the sedation flame, as shown in Figure 6. Here, "sedation flame" refers to the flame generated by the reaction between the slag and the slag sedation material. For example, if the imaging device 40 is installed at a position lower than the sedation frame, the imaging device 40 can be angled upwards to aim above the sedation frame and image the slug flow SF.

[0023] (Required process) Next, the volumetric flow rate or mass flow rate of the slug flow SF is determined from the captured images. In this embodiment, the volumetric flow rate of the slug flow SF is determined from the captured images. Specifically, image information of the slug flow SF captured by the imaging device 40 is received by the control device 42, and the control device 42 performs image analysis to determine the volumetric flow rate of the slug flow SF. The image information transmitted from the imaging device 40 may be still images captured at predetermined time intervals (for example, every second) or video images. If the image information transmitted from the imaging device 40 is still images, each still image is analyzed. On the other hand, if the image information transmitted from the imaging device 40 is video images, still images are extracted from the video at predetermined time intervals (for example, every second), and each extracted still image is analyzed.

[0024] In the image analysis of still images by the control device 42, the still image is first binarized. Then, the length of the high-brightness portion of the slug flow SF within the pre-set analysis area is measured as the apparent length. As shown in Figure 7(A), the length of the high-brightness portion of the slug flow SF can also be referred to as the width of the slug flow SF. Furthermore, the analysis area of ​​the still image by the control device 42 must be set to a height midway between the furnace opening 20C, which is the outflow start position of the slug flow SF, and the slag pot 22, and not affected by the sedation frame rising from the slag pot 22. The control device 42 then determines the width D (m) of the slug flow SF at a predetermined height and the distance H (m) from the measurement position of the width D to the outflow start position of the slug flow SF from the furnace opening 20C using the still image captured by the imaging device 40.

[0025] Next, the cross-sectional area S(m²) of the slug flow SF at the measurement position of width D. 2 ) to αD 2 This is how it is determined. Specifically, the control device 42 determines the cross-sectional area S. Also, α is a shape correction coefficient, and α=1 when the cross-sectional shape of the slug flow SF is a perfect circle (see Figure 7(B)).

[0026] Furthermore, assuming the free fall of the slug flow SF at the measurement position of width D is (2gH), the flow velocity V (m / s) of the slug flow SF is calculated as follows: 0.5 This is how it is determined. Specifically, the flow velocity V (m / s) is determined by the control device 42.

[0027] And the volumetric flow rate Q(m³) of the slug flow SF. 3 The flow rate ( / s) is calculated using the following equation (1). Specifically, the control device 42 uses the above flow velocity V and cross-sectional area S to determine the volumetric flow rate Q. Q=SV=αD 2 (2gH) 0.5 ...(1)

[0028] (Estimated process) Next, the amount of slag (mass of slag) discharged from the converter 20 is estimated based on the volumetric flow rate or mass flow rate. In this embodiment, the amount of intermediate slag discharged from the converter 20 is estimated based on the volumetric flow rate obtained in the above step.

[0029] First, at least, the tilting angle of the converter 20 at the start of the outflow of the slag flow SF, the shape of the converter 20, the volume of the converter 20, and the estimated value M of the mass of the slag in the furnace S The volume flow rate Q is converted into the mass flow rate ρQ (kg / s) using the bulk density ρ (kg / m 3 ) of the slag in the furnace, which is geometrically determined from the above. Specifically, the control device 42 converts the volume flow rate Q into the mass flow rate ρQ using at least the tilting angle of the converter 20, the shape of the converter 20, the volume of the converter 20, and the bulk density ρ. Note that the estimated value M S is obtained, for example, from the mass (actual value) of the first refining material charged into the converter 20, the mass of the oxides (as an example, silicon dioxide (SiO2), diphosphorus pentoxide (P2O5), manganese oxide (MnO), or a combination of one or more of these) generated by oxidation from the hot metal, and the mass (assumed value) of the slag from the previous cycle that was reused.

[0030] Method for obtaining the bulk density: As shown in FIG. 1(B), when the effective furnace volume of the converter 20 at the time when the converter is tilted and slag starts to flow out from the furnace mouth 20C is V DS , the volume of the molten iron is V M , and the volume of the slag is V S , then V S =V DS -V M is obtained, and when the mass of the slag is M S , the bulk density ρ = M S / V​​​​​​​​​​​​​​​​​Then, the slag mass (kg) is determined from the integrated mass flow rate ρQ ΣρQ (kg). In this way, the converter slag amount estimation method of this embodiment allows the volumetric flow rate Q of the slag to be discharged to be determined based on an image of the slag flow SF during intermediate slag discharge, and the slag mass can be determined from that volumetric flow rate Q.

[0032] The coefficient α in equation (1) is determined by parameter fitting, using either the integrated mass flow rate ρQ (kg / s) ΣρQ (kg), which was determined in advance during slag discharge from the converter 20, or the slag mass (kg) obtained using a weighing instrument (not shown) as the true value.

[0033] Next, the refining method in the converter 20 of this embodiment will be described. In the refining method of this embodiment, the operating conditions for the subsequent process are set based on the intermediate slag volume estimated by the converter slag volume estimation method. These operating conditions include the type of refining agent to be added to the molten metal (molten iron) in the converter 20 and the amount of the refining agent to be added.

[0034] Next, the control device 42, which controls the type and amount of smelting material added to the converter 20, will be described. As shown in Figures 5 and 6, image information of the slag flow SF captured by the imaging device 40 is sequentially transmitted to this control device 42. The imaging device 40 determines the volumetric flow rate Q of the slag flow SF based on the received image information. Then, the control device 42 determines the intermediate slag mass based on the volumetric flow rate Q.

[0035] The control device 42 sets the operating conditions for the subsequent process based on the determined amount of intermediate slag. Specifically, the control device 42 determines the type and amount of refining agent to be added to the molten iron in the converter 20, and operates the adding device (not shown) to add the refining agent to the molten iron in the converter 20. The control device 42 also controls the tilting mechanism 24 of the converter 20.

[0036] As shown in Figure 9, the control device 42 includes a CPU (Central Processing Unit) 43, a main memory 44 that provides temporary storage, an auxiliary storage device 45 that provides non-volatile storage, and an input / output interface (I / F) 46. The CPU 43, main memory 44, auxiliary storage device 45, and input / output I / F 46 are connected to each other via a bus 47.

[0037] The auxiliary storage device 45 can be implemented using a Hard Disk Drive (HDD), Solid State Drive (SSD), flash memory, etc. The auxiliary storage device 45 stores an estimation program 48 that causes the control device 42 to function as an estimation device for the amount of intermediate slag in the converter 20. The CPU 43 reads the estimation program 48 from the auxiliary storage device 45, loads it into the main memory 44, and sequentially executes the processes described in the estimation program 48, thereby enabling the control device 42 to function as an estimation device for the amount of intermediate slag in the converter 20.

[0038] The input / output interface 46 is connected to the imaging device 40. This configuration allows image information captured by the imaging device 40 to be stored in the auxiliary storage device 45 via the input / output interface 46 and analyzed by the CPU 43. The input / output interface 46 is also connected to the tilting mechanism 24 of the converter 20. Specifically, it is connected to the tilting control device of the tilting mechanism 24. This tilting control device is configured to operate the tilting mechanism 24 based on instructions from the control device 42 to control the tilting angle of the converter 20.

[0039] Next, the operation and effects of this embodiment will be described. In the estimation method of this embodiment, the amount of intermediate slag discharged from the converter 20 is determined using image analysis. Therefore, compared to, for example, the case where a weighing scale is used to determine the amount of intermediate slag discharged, the equipment costs are lower. Also, unlike mechanical measurement methods, it is not affected by thermal deformation or deterioration over time, making equipment maintenance easier. Furthermore, while mass measurement methods using weighing scales cannot obtain accurate measurement values ​​until the measurement values ​​stabilize after slag discharge is complete, the estimation method of this embodiment measures optically, so measurement values ​​and integrated values ​​can be obtained even during slag discharge, thus enabling stable determination of the amount of intermediate slag discharged.

[0040] Furthermore, the estimation method of this embodiment allows for the estimation of the intermediate slag volume from the converter 20 with higher accuracy compared to the method of geometrically determining the slag volume. Specifically, when geometrically determining the slag volume, the estimation accuracy may be low due to large variations in both the furnace shape and the state of the slag metal. In contrast, the estimation method of this embodiment improves estimation accuracy because the results, which reflect the effects of the above-mentioned variations, can be "directly" measured in the form of the slag flow volume using the imaging device 40.

[0041] Furthermore, with conventional methods for estimating the amount of sludge discharged, the subsequent processing can be optimized based on the result, which is the amount of intermediate sludge discharged. In contrast, the estimation method of this embodiment allows us to know the "elapsed" amount of intermediate sludge discharged in addition to the above processing. Therefore, the amount of sludge discharged itself can also be controlled. Specifically, with conventional methods, it is not possible to control the process so that sludge discharge is stopped when the sludge mass reaches a predetermined value; only the actual mass of sludge discharged is obtained. In contrast, with the estimation method of this embodiment, it is possible to control the process so that sludge discharge is stopped when the sludge volume reaches a predetermined value. With conventional methods, the "quality" of subsequent processes can be stabilized and improved by quantifying the "results" of intermediate sludge discharged, but with the estimation method of this embodiment, the "process" of intermediate sludge discharged can also be quantified in addition to the above, so the "quality" of the intermediate sludge discharged itself can be stabilized and improved.

[0042] Furthermore, in the estimation method of this embodiment, the imaging device 40 for imaging the slug flow SF is positioned such that the imaging direction SD of the imaging device 40 is tilted relative to the slag discharge direction DD of the converter 20 in a plan view, so the imaging device 40 is less affected by the sedation frame.

[0043] Furthermore, in the estimation method of this embodiment, if the imaging direction SD of the imaging device 40 that images the slug flow SF is perpendicular to the vertical direction VD when viewed from the side, the imaging device 40 can obtain highly accurate image information.

[0044] In the embodiments described above, the imaging device 40 and the control device 42 are connected by wire or wireless connection, but this disclosure is not limited to this configuration. For example, a removable image storage medium may be removed from the imaging device 40 and connected to the CPU 43 via the input / output I / F 46.

[0045] In the embodiment described above, the imaging direction SD of the imaging device 40 was tilted with respect to the slag discharge direction DD, but this disclosure is not limited to this configuration. For example, if the imaging device 40 is positioned above and the slag flow SF flowing down from the furnace opening 20C is imaged from above, the imaging direction SD of the imaging device 40 and the slag discharge direction DD may be in the same direction.

[0046] In the embodiment described above, the volumetric flow rate of the slug flow SF was determined by image analysis, and the amount of slag discharged (slag volume) was estimated from that volumetric flow rate. However, this disclosure is not limited to this configuration. For example, the volumetric flow rate of the slug flow SF and the mass flow rate may be determined by image analysis, and the amount of slag discharged may be estimated from that mass flow rate.

[0047] In the refining method in the converter 20 of the embodiment described above, the volumetric flow rate of the slag flow SF is determined by image analysis, the amount of slag discharged (slag volume) is estimated from the volumetric flow rate, and the operating conditions of the subsequent process are set based on the estimated intermediate slag discharge amount. However, this disclosure is not limited to this configuration. For example, the slag flow SF flowing out from the furnace opening of the converter 20 may be photographed, the width D of the slag flow SF may be determined from the photographed image, and the operating conditions of the subsequent process may be set based on the determined width D. In other words, the width D of the slag flow SF may be used as the slag discharge parameter. These operating conditions include the type of refining material to be added to the molten metal (molten iron) in the converter 20 and the amount of the refining material to be added. Specifically, if the slag discharge parameter is within a preset range (level), the amount of auxiliary raw materials (mainly CaO) added is set to a preset amount. On the other hand, if the slag discharge parameter is below the above range, the amount of auxiliary raw materials (mainly CaO) added is increased to more than the above set amount. Furthermore, if the slag discharge parameter exceeds the above range, the amount of auxiliary material (mainly CaO) added is reduced to less than the above set amount, or the amount of auxiliary material (mainly CaO) added is set to the above amount, while also adding an SiO2 source. Here, the SiO2 source refers to SiO itself, composite oxides containing SiO2, or alloys containing Si (which become oxidized SiO2). In other words, if there is little slag discharge, there is a lot of SiO2 in the furnace, so more CaO is added, and if there is a lot of slag discharge, there is an excess of CaO, so CaO is reduced or SiO2 is added to balance it. By controlling the CaO concentration / SiO2 concentration in the slag to a certain range in this way, the dephosphorization efficiency can be maximized. Moreover, when the width D of the slag flow SF is used as the slag discharge parameter as described above, calculations of slag bulk density and other calculations become unnecessary, simplifying the use of data processing. In particular, when operations are conducted with very little variation in slag density, the relationship between the width D of the slag flow SF and the mass flow rate ρQ becomes close to one-to-one. Therefore, by using the width D of the slag flow SF as a slag removal parameter, data processing can be easily utilized.

[0048] Next, the relationship between the waste volume obtained by image analysis in this embodiment and the waste volume obtained by geometric calculation will be explained based on Table 1 and Figure 8 below.

[0049] Table 1 below shows the slag volume obtained by image analysis using the estimation method of this embodiment for Examples 1 to 10, the slag volume obtained by geometric calculation, and the slag mass actually measured. In Table 1, the slag start tilt angle refers to the tilt of the converter at the start of slag discharge. Similarly, the slag end tilt angle refers to the tilt of the converter at the end of slag discharge.

[0050] [Table 1]

[0051] Figure 8 shows the relationship between the slag volume obtained by image analysis and the slag volume obtained by geometric calculation, based on the slag volume obtained by image analysis and the slag volume obtained by geometric calculation for Examples 1 to 10 in Table 1. As shown in Figure 8, the slag volume obtained by image analysis and the slag volume obtained by geometric calculation are generally close, although there is some variation. [Explanation of Symbols]

[0052] 20 Converter 40 Imaging device SD shooting method DD slag removal method SF Slug Style

Claims

1. The process involves photographing the slag flowing out of the converter's furnace opening using a single optical camera as a photographic device, A process for determining the volumetric flow rate of the sludge flow from an image captured by the optical camera, An estimation step for estimating the amount of slag discharged from the converter based on the volumetric flow rate, It has, In the aforementioned determination process, the width D (m) of the slag flow at a predetermined height and the distance H (m) from the measurement position of the width D to the point where the slag flow begins to flow out of the furnace opening are determined from the image of the slag flow, and the cross-sectional area S (m) of the slag flow at the measurement position is determined. ２ ) to αD 2 Assuming that the flow velocity V (m / s) at the measurement position is the free fall of the slug flow (2gH), 0.5 The volumetric flow rate Q (m³) of the slug flow is calculated as follows: ３ We find / s)) using equation (1), In the estimation step, at least the tilt angle of the converter at the start of the slag flow outflow, the shape of the converter, the volume of the converter, and the bulk density ρ (kg / m³) which is geometrically determined from the volumetric flow rate are used to convert the volumetric flow rate to a mass flow rate ρQ (kg / s), and the slag mass (kg) is determined as the amount of slag to be discharged from the integrated value ΣρQ (kg). A method for estimating the amount of converter slag, applicable when the bulk density ρ is 137 kg / m³ or more and 218 kg / m³ or less. 4366 α 2 (22) 0.5 ・・・(1)

2. The method for estimating the amount of converter slag according to claim 1, wherein the direction of the optical camera that photographs the slag flow is inclined with respect to the slag discharge direction of the converter in a plan view.

3. The method for estimating the amount of converter slag according to claim 1, wherein the direction of the optical camera that photographs the slag flow is perpendicular to the vertical direction when viewed from the side.

4. The method for estimating the amount of converter slag according to claim 1, wherein, at the time of slag discharge from the converter, the integrated value of the mass flow rate ρQ (kg / s) ΣρQ (kg) or the slag mass (kg) obtained using a weighing instrument is taken as the true value, and α in equation (1) is determined by parameter fitting.

5. A refining method comprising setting the operating conditions of a subsequent process based on the amount of slag estimated by the converter slag estimation method described in any one of claims 1 to 4.

6. The refining method according to claim 5, wherein the operating conditions include the type of refining agent to be added to the molten metal in the converter and the amount of the refining agent to be added.

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