A method for improving the direct tapping ratio of semi-steel converter

Abstract

The application discloses a method for improving the direct tapping ratio of semi-steel converter smelting, which comprises the following steps: (1) obtaining the physical property parameters of semi-steel molten iron, scrap steel and the last furnace slag; (2) according to the physical property parameters of the obtained slag, the target basicity and the target magnesium oxide content of the semi-steel smelting slag, the linear programming method is used to calculate the adding amount of lime, limestone and dolomite; (3) based on the physical property parameters of semi-steel molten iron, scrap steel and the last furnace slag obtained in step (1) and the adding amount of lime, limestone and dolomite obtained in step (2), when the composition of the molten steel reaches the target value, the end-point molten steel temperature and the process oxygen blowing amount are calculated according to the material balance and the heat balance relationship between all the materials entering the furnace and the output materials. The method improves the stability of the smelting process and the end-point, realizes the effect of improving the direct tapping ratio of the converter, shortening the smelting period and reducing the smelting cost.

Description

Technical Field

[0001] The invention belongs to the technical field of converter steelmaking, in particular to a method for improving the direct tapping ratio of semi-steel converter smelting. Background Art

[0002] The goal of semi-steel converter steelmaking is to continuously oxidize carbon and phosphorus in molten iron through slag formation and oxygen blowing, raising the molten iron temperature and ultimately achieving the desired tapping composition and temperature. Currently, most small and medium-sized converters have low-level hardware and software capabilities and lack a secondary control model. The smelting process relies on manual experience, which relies on observing flame characteristics during steelmaking and analyzing production control data to determine the molten steel temperature. This makes it difficult to achieve stable and accurate results. Most heats require temperature measurement after pouring the furnace, resulting in a low direct tapping rate. Furthermore, this process increases operator workload and poses safety risks, while also prolonging the smelting process, reducing production efficiency, and impacting steel quality and raw material costs. Therefore, a method to increase the direct tapping rate in semi-steel converter smelting is urgently needed to reduce energy consumption and production costs, thereby enhancing the market competitiveness of enterprises.

[0003] The Chinese patent application number 201910486484.8 discloses "a method for improving the tapping rate of a converter". By studying historical production records, the historical production records are divided into different steel grades, and the planned production steel grades are matched with them. The production operating parameters with the highest tapping rate are preferentially selected as the optimal production operating parameters. Although this method can improve the direct tapping rate, the terminal temperature control still relies on manual experience, and the application scenarios are limited. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for improving the direct tapping ratio of semi-steel converter smelting, so as to achieve precise control of the final composition and temperature of the converter.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention includes the following steps: (1) obtaining the physical properties of semi-ferrous metal, scrap steel and slag from the previous furnace;

[0006] (2) Based on the obtained physical properties of the slag, the target basicity of the semi-steelmaking slag, and the target magnesium oxide content, the amount of lime, limestone, and dolomite to be added is calculated using the linear programming method;

[0007] (3) Based on the physical properties of the semi-iron molten steel, scrap steel and slag from the previous furnace obtained in step (1) and the added amounts of lime, limestone and dolomite obtained in step (2), when the molten steel composition reaches the target value, the terminal molten steel temperature and the process oxygen blowing amount are calculated according to the material balance and heat balance relationship between all the incoming materials and the output materials;

[0008] (4) When the final molten steel temperature - target tapping temperature > the maximum allowable temperature difference: use scale cooling, take the target tapping temperature as the criterion, recalculate the material balance and heat balance relationship, and obtain the scale addition amount and the corrected oxygen blowing amount. In this case, the total oxygen blowing amount = the corrected oxygen blowing amount;

[0009] When |molten steel temperature - target tapping temperature|≤the maximum allowable temperature difference: tapping directly. In this case, the total oxygen blowing amount = the process oxygen blowing amount.

[0010] When the target tapping temperature - the final molten steel temperature > the maximum allowable temperature difference: continue blowing oxygen to oxidize the iron in the molten steel. Based on the target tapping temperature and the heat release of iron oxidation, calculate the relationship between material balance and heat balance to obtain the supplementary oxygen blowing amount. In this case, the total oxygen blowing amount = process oxygen blowing amount + supplementary oxygen blowing amount.

[0011] (5) Blowing is carried out according to the total oxygen blowing amount calculated in step (4), and steel is directly tapped without turning the furnace over.

[0012] Furthermore, the physical properties of the semi-ferrous metal in step (1) include: temperature, carbon content, sulfur content, phosphorus content and weight; the physical properties of the scrap steel include: temperature, carbon content, sulfur content, phosphorus content, silicon content, manganese content and weight; the physical properties of the slag include: calcium oxide content, silicon dioxide content, magnesium oxide content, aluminum oxide content, manganese oxide content and ferrous oxide content.

[0013] Furthermore, in step (2), the target basicity of the semi-steelmaking slag is 3.0-4.0, and the target magnesium oxide content is 10.0-12.0%.

[0014] Furthermore, the target values ​​of the molten steel composition in step (3) are: C 0.06-0.10%, P 0.015-0.025%.

[0015] Furthermore, in step (4), the target tapping temperature is 1630-1650°C.

[0016] Furthermore, in step (4), the maximum allowable temperature difference is 5°C to 15°C.

[0017] The beneficial effects of adopting the above technical solution are as follows: the present invention calculates the addition amount of lime, limestone and dolomite based on the physical properties of semi-iron water, scrap steel, and slag from the previous furnace and the target alkalinity and magnesium oxide content of the slag, and obtains the addition amount of iron oxide scale and the total oxygen blowing amount based on the material balance and heat balance relationship between all the materials entering the furnace and the output materials and the target composition and temperature of the steel grade; the addition amount of auxiliary materials and the oxygen blowing amount can be accurately calculated in advance based on the target steel tapping composition and temperature, thereby improving the stability of the smelting process and the end point; the end point composition and temperature of the converter can be accurately controlled, thereby achieving the effects of increasing the direct steel tapping ratio of the converter, shortening the smelting cycle and reducing the smelting cost; and the operating environment of the operators can be improved, thereby improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 It is a process flow diagram of the present invention. DETAILED DESCRIPTION

[0020] The method for improving the direct tapping ratio of semi-steel converter smelting includes the following steps: (1) obtaining the physical properties of semi-steel molten steel, scrap steel and slag from the previous furnace; the physical properties of the semi-steel molten steel include: temperature, carbon content, sulfur content, phosphorus content and weight; the physical properties of the scrap steel include: temperature, carbon content, sulfur content, phosphorus content, silicon content, manganese content and weight; the physical properties of the slag include: calcium oxide content, silicon dioxide content, magnesium oxide content, aluminum oxide content, manganese oxide content and ferrous oxide content.

[0021] (2) Based on the obtained physical properties of the slag, the target basicity of the semi-steelmaking slag, and the target magnesium oxide content, the linear programming method is used to calculate the addition amounts of lime, limestone, and dolomite; the target basicity of the semi-steelmaking slag is 3.0-4.0, and the target magnesium oxide content is 10.0-12.0%.

[0022] (3) Based on the physical properties of the semi-ferrous metal, scrap steel and slag from the previous furnace obtained in step (1) and the added amounts of lime, limestone and dolomite obtained in step (2), when the molten steel composition reaches the target value, the terminal molten steel temperature and the process oxygen blowing amount are calculated according to the material balance and heat balance relationship between all the incoming materials and the output materials; the calculation method can adopt a conventional method; the target values ​​of the molten steel composition are: C 0.06-0.10%, P 0.015-0.025%.

[0023] (4) The target tapping temperature is 1630-1650℃, and the maximum allowable temperature difference is 5℃-15℃. That is, the maximum temperature difference is selected between 5℃ and 15℃ according to the different requirements of steel grades. The total oxygen blowing amount is calculated as follows:

[0024] (4.1) When the final molten steel temperature - the target tapping temperature > the maximum allowable temperature difference: use scale cooling, take the target tapping temperature as the criterion, recalculate the material balance and heat balance relationship, and obtain the scale addition amount and the corrected oxygen blowing amount. In this case, the total oxygen blowing amount = the corrected oxygen blowing amount. The calculation formulas for the scale addition amount and the corrected oxygen blowing amount are as follows:

[0025] Amount of iron oxide scale added = (end point molten steel temperature - target tapping temperature) * 20 (Ⅰ);

[0026] Corrected oxygen blowing amount = process oxygen blowing amount - iron oxide scale added amount * 0.15 (Ⅱ);

[0027] In the above formula: the final molten steel temperature and the target tapping temperature are both in °C; the process oxygen blowing volume is in m 3 ;Amount of iron oxide added, unit: kg;

[0028] (4.2) When |molten steel temperature - target tapping temperature| ≤ the maximum allowable temperature difference: tapping is performed directly. In this case, the total oxygen blowing rate = the process oxygen blowing rate.

[0029] (4.3) When the target tapping temperature minus the final molten steel temperature is greater than the maximum allowable temperature difference, continue blowing oxygen to oxidize the iron in the molten steel. Based on the target tapping temperature and the heat release of iron oxidation, calculate the relationship between material balance and heat balance to obtain the supplementary oxygen blowing amount. In this case, the total oxygen blowing amount = the process oxygen blowing amount + the supplementary oxygen blowing amount. The supplementary oxygen blowing amount is calculated using the following formula (III):

[0030] Supplementary oxygen blowing amount = (target tapping temperature - final molten steel temperature) * 6.67 (III);

[0031] In formula (III): the final molten steel temperature and the target tapping temperature, both in °C; the amount of supplementary oxygen blowing, in m 3 .

[0032] (5) Blowing is carried out according to the total oxygen blowing amount calculated in step (4), and steel is directly tapped without turning the furnace over.

[0033] Example 1: Figure 1 As shown, the method for improving the direct tapping ratio of semi-steel converter smelting adopts the following steps.

[0034] (1) Obtain the physical properties of semi-iron molten steel, scrap steel and the previous furnace slag. The physical properties of semi-iron molten steel include: temperature, carbon content, sulfur content, phosphorus content and weight; the physical properties of scrap steel include: temperature, carbon content, sulfur content, phosphorus content, silicon content, manganese content and weight; the physical properties of converter slag include: calcium oxide content, silicon dioxide content, magnesium oxide content, aluminum oxide content, manganese oxide content and ferrous oxide content. The specific physical properties of semi-iron molten steel, scrap steel and the previous furnace slag are shown in Table 1;

[0035]

[0036] (2) Based on the physical properties of the slag obtained in step (1), when the target basicity of the semi-steelmaking slag is 4.0 and the magnesium oxide content is 11.0, the existing linear programming method is used to calculate the addition amounts of lime, limestone, and dolomite to be 1250 kg, 100 kg, and 800 kg, respectively.

[0037] (3) Based on the physical properties of the semi-iron molten steel, scrap steel and slag from the previous furnace obtained in step (1) and the addition amounts of lime, limestone and dolomite obtained in step (2); when the carbon content of the molten steel reaches 0.08% and the phosphorus content reaches 0.02%, according to the material balance and heat balance relationship between all the incoming materials and the output materials, the existing calculation method is used to calculate the terminal molten steel temperature to be 1601℃ and the process oxygen blowing volume to be 2650m 3 .

[0038] (4) In this embodiment, the target tapping temperature is 1640°C, the allowable temperature difference is ≤10°C, and the target tapping temperature minus the final molten steel temperature is 39°C, which is greater than the maximum allowable temperature difference of 10°C. At this time, oxygen should be blown continuously to oxidize the iron in the molten steel. Based on the target tapping temperature and the heat release of iron oxidation, the relationship between material balance and heat balance is calculated, and the supplementary oxygen blowing amount is 39*6.67=260m 3 The total oxygen blowing volume is the process oxygen blowing volume + the supplementary oxygen blowing volume, a total of 2650+260=2910m 3 .

[0039] (5) Blowing is carried out according to the calculated total oxygen blowing amount, and then the steel is directly tapped without turning the furnace over; after testing, the temperature of the molten steel is 1637.

[0040] Example 2: Figure 1 As shown, the method for improving the direct tapping ratio of semi-steel converter smelting adopts the following steps.

[0041] (1) Obtain the physical properties of semi-iron molten steel, scrap steel and the previous furnace slag. The physical properties of semi-iron molten steel include: temperature, carbon content, sulfur content, phosphorus content and weight; the physical properties of scrap steel include: temperature, carbon content, sulfur content, phosphorus content, silicon content, manganese content and weight; the physical properties of converter slag include: calcium oxide content, silicon dioxide content, magnesium oxide content, aluminum oxide content, manganese oxide content and ferrous oxide content. The specific physical properties of semi-iron molten steel, scrap steel and the previous furnace slag are shown in Table 2;

[0042]

[0043] (2) Based on the physical properties of the slag obtained in step (1), when the target basicity of the semi-steelmaking slag is 3.0 and the magnesium oxide content is 12.0, the existing linear programming method is used to calculate the addition amounts of lime, limestone, and dolomite to be 1120 kg, 100 kg, and 850 kg, respectively.

[0044] (3) Based on the physical properties of the semi-iron molten steel, scrap steel and slag from the previous furnace obtained in step (1) and the addition amounts of lime, limestone and dolomite obtained in step (2); when the carbon content of the molten steel reaches 0.06% and the phosphorus content reaches 0.015%, according to the material balance and heat balance relationship between all the incoming materials and the output materials, the existing calculation method is used to calculate the terminal molten steel temperature to be 1635℃ and the process oxygen blowing volume to be 2720m 3 .

[0045] (4) In this embodiment, the target tapping temperature is 1640℃, the allowable temperature difference is ≤10℃, the target tapping temperature minus the final molten steel temperature is 5℃, which is less than the maximum allowable temperature difference of 10℃; at this time, the total oxygen blowing amount is the process oxygen blowing amount of 2720m 3 .

[0046] (5) Blowing is carried out according to the calculated total oxygen blowing amount, and then the steel is directly tapped without turning the furnace over; after testing, the temperature of the molten steel is 1641.

[0047] Example 3: Figure 1 As shown, the method for improving the direct tapping ratio of semi-steel converter smelting adopts the following steps.

[0048] (1) Obtain the physical properties of semi-iron molten steel, scrap steel and the previous furnace slag. The physical properties of semi-iron molten steel include: temperature, carbon content, sulfur content, phosphorus content and weight; the physical properties of scrap steel include: temperature, carbon content, sulfur content, phosphorus content, silicon content, manganese content and weight; the physical properties of converter slag include: calcium oxide content, silicon dioxide content, magnesium oxide content, aluminum oxide content, manganese oxide content and ferrous oxide content. The specific physical properties of semi-iron molten steel, scrap steel and the previous furnace slag are shown in Table 3;

[0049]

[0050] (2) Based on the physical properties of the slag obtained in step (1), when the target basicity of the semi-steelmaking slag is 3.0 and the magnesium oxide content is 12.0, the existing linear programming method is used to calculate the addition amounts of lime, limestone, and dolomite to be 1050 kg, 100 kg, and 920 kg, respectively.

[0051] (3) Based on the physical properties of the semi-iron molten steel, scrap steel and slag from the previous furnace obtained in step (1) and the addition amounts of lime, limestone and dolomite obtained in step (2); when the carbon content of the molten steel reaches 0.1% and the phosphorus content reaches 0.025%, according to the material balance and heat balance relationship between all the materials entering the furnace and the output materials, the existing calculation method calculates that the terminal molten steel temperature is 1680℃ and the process oxygen blowing volume is 2830m 3 .

[0052] (4) In this embodiment, the target tapping temperature is 1630°C, the allowable temperature difference is ≤10°C, and the terminal molten steel temperature minus the target tapping temperature is 50°C, which is greater than the maximum allowable temperature difference of 10°C. At this time, the iron oxide scale is used for cooling. Based on the target tapping temperature, the material balance and heat balance relationship are recalculated, and the amount of iron oxide scale added is 50*20=1000kg. The total oxygen blowing amount is the corrected oxygen blowing amount 2830-150=2680m 3 .

[0053] (5) Blowing is carried out according to the calculated total oxygen blowing amount, and then the steel is directly tapped without pouring the furnace; after testing, the temperature of the molten steel is 1635.

[0054] Statistical example: When using the conventional method, a total of 500 heats were recorded, of which 100 were directly tapped and 400 required temperature measurement after pouring, resulting in a direct tapping ratio of 20%. After using this method, a total of 800 heats were recorded, of which 650 were directly tapped and 150 required temperature measurement after pouring, resulting in a direct tapping ratio of 81%.

Claims

1. A method for improving the direct tapping rate of semi-steel converter smelting, characterized in that: The method comprises the following steps: (1) obtaining the physical properties of semi-ferrous metal, scrap steel and slag from the previous furnace; (2) Based on the obtained physical properties of the slag, the target basicity of the semi-steelmaking slag, and the target magnesium oxide content, the amount of lime, limestone, and dolomite to be added is calculated using the linear programming method; (3) Based on the physical properties of the semi-iron molten steel, scrap steel and slag from the previous furnace obtained in step (1) and the added amounts of lime, limestone and dolomite obtained in step (2), when the molten steel composition reaches the target value, the terminal molten steel temperature and the process oxygen blowing amount are calculated according to the material balance and heat balance relationship between all the incoming materials and the output materials; (4) When the final molten steel temperature - target tapping temperature > the maximum allowable temperature difference: use scale cooling, take the target tapping temperature as the criterion, recalculate the material balance and heat balance relationship, and obtain the scale addition amount and the corrected oxygen blowing amount. In this case, the total oxygen blowing amount = the corrected oxygen blowing amount; When |molten steel temperature - target tapping temperature|≤the maximum allowable temperature difference: tapping directly. In this case, the total oxygen blowing amount = the process oxygen blowing amount. When the target tapping temperature - the final molten steel temperature > the maximum allowable temperature difference: continue blowing oxygen to oxidize the iron in the molten steel. Based on the target tapping temperature and the heat release of iron oxidation, calculate the relationship between material balance and heat balance to obtain the supplementary oxygen blowing amount. In this case, the total oxygen blowing amount = process oxygen blowing amount + supplementary oxygen blowing amount. (5) Blowing is carried out according to the total oxygen blowing amount calculated in step (4), and steel is directly tapped without turning the furnace over.

2. The method for improving the direct tapping rate of semi-steel converter smelting according to claim 1, characterized in that: The physical properties of the semi-ferrous metal in step (1) include: temperature, carbon content, sulfur content, phosphorus content and weight; the physical properties of the scrap steel include: temperature, carbon content, sulfur content, phosphorus content, silicon content, manganese content and weight; the physical properties of the slag include: calcium oxide content, silicon dioxide content, magnesium oxide content, aluminum oxide content, manganese oxide content and ferrous oxide content.

3. The method for improving the direct tapping rate of semi-steel converter smelting according to claim 1, characterized in that: In the step (2), the target basicity of the semi-steelmaking slag is 3.0-4.0, and the target magnesium oxide content is 10.0-12.0%.

4. The method for improving the direct tapping rate of semi-steel converter smelting according to claim 1, characterized in that: The target values ​​of the molten steel composition in step (3) are: C 0.06-0.10%, P 0.015-0.025%.

5. The method for improving the direct tapping rate of semi-steel converter smelting according to claim 1, characterized in that: In the step (4), the target tapping temperature is 1630-1650°C.

6. A method for improving the direct tapping rate of semi-steel converter smelting according to any one of claims 1 to 5, characterized in that: In the step (4), the maximum allowable temperature difference is 5°C to 15°C.

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