Method for reducing accumulations in hearth center of high-titanium vanadium titano-magnetite during blast-furnace smelting

Abstract

Disclosed in the present invention is a method for reducing accumulations in a hearth center of high-titanium vanadium titano-magnetite during blast-furnace smelting, comprising: during blast-furnace smelting, formulating an air supply system: determining a standard air speed on the basis of a slag-to-iron ratio, the furnace slag TiO2 content and the molten iron Ti content; calculating an actual intake air volume of a blast furnace on the basis of the standard air speed; and comparing the actual intake air volume of the blast furnace with the air volume calculated during production, and adjusting the air intake area and an actual air speed; and during blast-furnace smelting, formulating a charging system: the distance between the edge placement point of iron-containing furnace charge and furnace throat steel bricks is 0.32-0.48 m, the distance between coke and the furnace throat steel bricks is 0.18-0.36 m, and the distance between the coke edge placement point and the furnace wall is less than that between the ore edge placement point and the furnace wall. By means of the method of the present invention, the activity of the blast furnace hearth center is improved, and the furnace bottom center temperature as an important index for representing the accumulation of the hearth center is gradually increased; and the blast-furnace smelting strength is improved, the smelting cycle is accelerated, and the furnace temperature is reduced.

Description

Method for reducing accumulation in the hearth center during blast furnace smelting of high-titanium vanadium-titanium magnetite

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 11, 2023, with application number 202311011735.X and invention name “Method for reducing accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the field of blast furnace ironmaking, and specifically relates to a method for smelting high-titanium vanadium-titanium magnetite in a blast furnace, and more specifically relates to a method for reducing accumulation in the center of a hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite. Background Art

[0003] Most of the vanadium-titanium magnetites in the Panzhihua area are high-titanium vanadium-titanium magnetites with low TFe (total iron) grade and high TiO2 content. After the mineral processing process, V and Ti are isomorphously present in the iron concentrate. Therefore, blast furnace smelting has problems such as high slag-to-iron ratio, high TiO2 content in slag, and easy thickening of slag.

[0004] The slag has a high TiO2 content and is easily reduced to form TiC, TiN and its solid solution Ti(C,N) during the smelting process; under blast furnace smelting conditions, this is a high-melting-point phase that cannot be melted. In severe cases, TiC, TiN and its solid solution Ti(C,N) are mixed with the slag and iron in the blast furnace, especially in the center of the hearth, and cannot be discharged from the blast furnace through the iron mouth in time. The volume gradually increases to form an extremely viscous mixture, thus forming a hearth accumulation. These deposits rich in TiC, TiN and their solid solution Ti(C,N) are extremely harmful to the stable and smooth operation of the blast furnace and the intensification of smelting. Reducing the formation of these deposits and discharging them out of the furnace is the basis for maintaining the stable and smooth operation of high-titanium vanadium-titanium magnetite in blast furnace smelting and further improving the smelting intensity.

[0005] Although TiO2 is inevitably reduced in the slag during the blast furnace smelting process, the formation of Ti(C,N)-rich deposits can be avoided by controlling the generated Ti(C,N) to an appropriate level and preventing the slag from becoming immobile in localized areas for extended periods, thereby gradually enriching Ti(C,N). The hearth center is the area of ​​the blast furnace most difficult for heat and kinetic energy to reach. It is also the area where the slag temperature is most susceptible to dropping and where the generated Ti(C,N) is most likely to accumulate, forming viscous deposits. The formation of deposits in this area poses the greatest threat to the stable and smooth operation of the blast furnace and the difficulty in maintaining furnace conditions.

[0006] Based on the above, it is necessary to develop a method for reducing the accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to reduce the formation of deposits rich in TiC, TiN and their solid solution Ti(C,N) in the center of the hearth during the blast furnace smelting process of high-titanium vanadium-titanium magnetite, maintain the stable and smooth blast furnace smelting of high-titanium vanadium-titanium magnetite and further improve the blast furnace smelting intensity.

[0009] Based on this, it is necessary to adopt the following technical solutions to address the above technical issues:

[0010] The present invention provides a method for reducing accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite. The blast furnace comprises, from top to bottom along its axial direction, a furnace throat, a furnace body, a furnace waist, a furnace belly, a furnace hearth, and a furnace bottom. A layer of radial tuyere is uniformly distributed in the hearth along the circumference of the blast furnace. The method reduces accumulation in the center of the hearth by adopting a reasonable air supply system and a charging system, comprising:

[0011] During the blast furnace smelting process, formulate the air supply system:

[0012] Determine the standard wind speed based on the slag-iron ratio, TiO2 content in the slag and Ti content in the molten iron;

[0013] The actual air volume entering the blast furnace is calculated based on the standard wind speed;

[0014] Compare the actual air volume entering the blast furnace with the air volume counted during production, and adjust the air inlet area and actual wind speed;

[0015] During the blast furnace smelting process, a charging system is formulated: the distance between the edge of the iron-containing charge and the throat steel bricks is 0.32 to 0.48 m, the distance between the coke and the throat steel bricks is 0.18 to 0.36 m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

[0016] In some embodiments, the blast furnace has an effective volume of 1200m 3 and above blast furnaces.

[0017] In some embodiments, the blast furnace has an effective volume of 1200m 3 、1350m 3 、1750m 3 and 2000m 3 blast furnace.

[0018] In some embodiments, 2 to 4 rings of material are used for loading, and the angle difference between the outer ring of the ore and the outer focus is controlled at -0.5 to -1.0°, and the angle difference between the inner ring of the ore and the inner focus is controlled at 5.5 to 6.0°.

[0019] In some embodiments, "determining the standard wind speed based on the slag-iron ratio, the TiO2 content in the slag, and the Ti content in the molten iron" is determined by the following formula (1):

[0020] V=a×D h +b×R slag +c×(TiO2) / Ti (1)

[0021] In formula (1), V is the standard wind speed, m / s; D h is the furnace diameter, m; R slag is the slag-iron ratio, kg / t; (TiO2) is the TiO2 content in the slag, %; Ti is the Ti content in the molten iron, %; a, b, c are coefficients, a is 27~28, b is -0.17~-0.19, and c is 0.52~0.58.

[0022] In some embodiments, the coefficients a, b, and c in formula (1) simultaneously take larger values ​​or smaller values ​​within the value range.

[0023] In some embodiments, the effective volume is 1200m 3 The blast furnace has a throat diameter of 6.0m, the distance between the edge of the iron-containing charge and the throat steel bricks is 0.32-0.38m, the distance between the coke and the throat steel bricks is 0.18-0.28m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

[0024] In some embodiments, the effective volume is 1350m 3 The blast furnace has a throat diameter of 6.3m, the distance between the edge of the iron-containing charge and the throat steel bricks is 0.33-0.40m, the distance between the coke and the throat steel bricks is 0.19-0.30m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

[0025] In some embodiments, the effective volume is 1750m 3 The blast furnace has a throat diameter of 6.9m, the distance between the edge of the iron-containing charge and the throat steel bricks is 0.37-0.43m, the distance between the coke and the throat steel bricks is 0.21-0.32m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

[0026] In some embodiments, the effective volume is 2000m 3 The blast furnace has a throat diameter of 7.6m, the distance between the edge of the iron-containing charge and the throat steel bricks is 0.40-0.48m, the distance between the coke and the throat steel bricks is 0.23-0.36m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

[0027] The present invention has the following beneficial technical effects:

[0028] After implementation of the method for reducing accumulation in the hearth center during blast furnace smelting of high-titanium vanadium-titanium magnetite of the present invention, the activity of the hearth center of the blast furnace is improved, and the center temperature of the furnace bottom, one of the important indicators characterizing the accumulation in the hearth center, gradually increases; the blast furnace smelting intensity is improved, the smelting cycle is accelerated, and the furnace temperature is reduced; every 100 iron tappings, the Ti and Si contents of the molten iron decrease, and the difference between the Ti content and the Si content of the molten iron, Ti-Si, is 0.01 to 0.065%. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with specific embodiments.

[0030] The blast furnace is composed of the throat, body, waist, bosh, hearth and bottom along its axis from top to bottom. A layer of radial tuyere is evenly distributed along the circumference of the blast furnace in the hearth. The accumulation in the center of the hearth is reduced by adopting a reasonable air supply system and charging system.

[0031] Lowering the reaction temperature and shortening the reaction time are important measures to reduce the formation of Ti(C,N). A reasonable air supply system can transfer heat and kinetic energy to the hearth center in a timely manner, which has a positive effect on reducing the formation of deposits in the hearth center and gradually eliminating them before they have a serious adverse effect on the blast furnace. The heat input and kinetic energy of the hearth area in the blast furnace mainly come from the hearth gas generated by the blast in front of the hearth tuyere and the combustion of coke and injected coal. A reasonable air supply system is a key factor in the timely transfer of heat and kinetic energy to the hearth center during the production process. Under the condition that the number and length of tuyere have been determined, adjusting the air inlet area, air volume, and air temperature according to different raw material conditions is the key to achieving an active hearth center. Combined with an appropriate charging system and thermal system, stable and smooth operation and high-intensity smelting of high-titanium vanadium-titanium magnetite blast furnace can be achieved.

[0032] The specific steps include:

[0033] (1) According to the raw fuel consumption and chemical composition, calculate the actual air volume entering the furnace under standard conditions, that is, the air volume counted during production.

[0034] (2) The wind speed calculated during production is obtained from the air inlet area and the air volume calculated during production.

[0035] (3) Determine the standard wind speed according to different raw material conditions. 3 、1350m 3 、1750m 3 and 2000m 3 For blast furnaces, the standard wind speed can be determined according to the following formula:

[0036] V=a×D h +b×Rslag +c×(TiO2) / Ti (1)

[0037] In formula (1), V is the standard wind speed, m / s; D h is the furnace diameter, m; R slag is the calculated slag-iron ratio, kg / t; (TiO2) is the TiO2 content in the slag, %; Ti is the Ti content in the molten iron, %; a, b, c are coefficients, a is 27~28, b is -0.17~-0.19, c is 0.52~0.58, a, b, c can take larger or smaller values ​​at the same time, for example, when a and c are 27 and 0.52 respectively, b is -0.19, when a and c are 28 and 0.58 respectively, c is -0.17.

[0038] The actual air volume entering the blast furnace is calculated based on the standard wind speed; the actual air volume entering the blast furnace is compared with the air volume statistically calculated during production, and the air inlet area and actual wind speed are adjusted; the air volume and slag-iron ratio are obtained according to the method of the existing technical document "Ironmaking Calculation Analysis" 2010 edition, pages 6 to 43.

[0039] When the above method is adopted to adjust the air supply system, a charging system that appropriately promotes the development of coal gas flow at the edge of the block column should be adopted accordingly. 3 The blast furnace has a throat diameter of 6.0m. According to the results of material flow trajectory measurement, the distance between the edge of the iron-containing furnace charge and the furnace throat steel bricks at different material lines is 0.32-0.38m, the distance between the coke and the furnace throat steel bricks is 0.18-0.28m, and the distance between the coke edge and the furnace wall is smaller than that of the ore. The effective volume is 1350m 3 The blast furnace has a throat diameter of 6.3m, the distance between the edge of the iron-containing charge and the throat brick is 0.33-0.40m, the distance between the coke and the throat brick is 0.19-0.30m, and the distance between the edge of the coke and the furnace wall is less than that of the ore. The effective volume is 1750m 3 The blast furnace has a throat diameter of 6.9m, the distance between the edge of the iron-containing charge and the throat bricks is 0.37-0.43m, the distance between the coke and the throat bricks is 0.21-0.32m, and the distance between the edge of the coke and the furnace wall is less than that of the ore. The effective volume is 2000m 3 The blast furnace has a throat diameter of 7.6m, the distance between the edge of the iron-containing charge and the throat steel bricks is 0.40-0.48m, the distance between the coke and the throat steel bricks is 0.23-0.36m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

[0040] Example 1:

[0041] The effective volume is 1750m 3For a blast furnace with a hearth diameter of 9.5 m, under the conditions of a slag-iron ratio of 540 kg / t, a TiO2 content of about 22.0%, and a Ti content of 0.185% in molten iron, according to formula (1), if a, b, and c are 27, 0.52, and -0.17 and 28, 0.58, and -0.19 respectively, the standard wind speeds are 226.5 m / s and 232.4 m / s respectively.

[0042] In actual production, according to the existing technical document "Ironmaking Calculation Analysis", the actual air volume into the blast furnace is 3623m 3 / min, which is 549m lower than the air volume counted during production. 3 / min, the pig iron output is about 4440-4500t / d, and the average Ti and Si contents of molten iron per 100 times are 0.272% and 0.241% respectively. 2 Shrink to 0.2615m 2 Under the same other conditions, based on the calculated air volume, the standard wind speed was increased from 216 m / s to 231 m / s. Simultaneously, the charging system was adjusted as shown in Tables 1 and 2, with the overall charge shifted toward the center. The edge of the iron-containing charge landed 0.37 m from the furnace wall, and the edge of the coke landed 0.21 m from the furnace wall. Following these measures, the activity of the blast furnace hearth center increased. The furnace bottom center temperature, a key indicator of accumulation in the hearth center, gradually increased from 589°C to stabilize between 608 and 610°C. The blast furnace's smelting intensity increased, the smelting cycle was accelerated, and the furnace temperature was lowered. The average Ti and Si contents of the molten iron per 100 times were reduced to 0.185% and 0.129%, respectively, with a difference of 0.056%. Daily pig iron production increased to 4,700 to 4,800 t / d.

[0043] Table 1 A 1750m 3 Blast furnace charging system before adjustment

[0044] Table 2 A certain 1750m 3 Blast furnace charging system after adjustment

[0045] Example 2:

[0046] The effective volume is 1200m 3 For a blast furnace with a hearth diameter of 8.2 m, under the conditions of a slag-iron ratio of about 620 kg / t, a TiO2 content of about 22.0%, and a Ti content of 0.221% in molten iron, according to formula (1), if a, b, and c are 27, 0.52, and -0.19 and 28, 0.58, and -0.17 respectively, the standard wind speeds are 167.8 m / s and 169.5 m / s respectively.

[0047] In actual production, according to the existing technical document "Ironmaking Calculation Analysis", the actual air volume of the blast furnace is 2620m 3 / min, which is 325m lower than the air volume counted during production 3 / min, the pig iron output is about 3250-3300t / d, and the average Ti and Si contents of molten iron per 100 times are 0.230% and 0.197% respectively. 2 Reduced to 0.2600m 2 Under the same other conditions, based on the calculated air volume, the standard wind speed was increased from 163 m / s to 168 m / s. Simultaneously, the charging system was adjusted as shown in Tables 3 and 4, with the overall charge shifted toward the center. The edge of the iron-containing charge landed 0.33 m from the furnace wall, and the edge of the coke landed 0.19 m from the furnace wall. Following these measures, the activity of the blast furnace hearth center increased. The furnace bottom center temperature, a key indicator of accumulation in the hearth center, gradually increased from 478°C to stabilize between 505 and 510°C. The blast furnace's smelting intensity increased, the smelting cycle was accelerated, and the furnace temperature was reduced. The Ti and Si contents of the molten iron decreased to 0.221% and 0.168%, respectively, with a difference of 0.053%. Daily pig iron production increased to 3,350 to 3,400 t / d.

[0048] Table 3 A certain 1200m 3 Blast furnace charging system before adjustment

[0049] Table 4: 1200m 3 Blast furnace charging system after adjustment

[0050] Example 3:

[0051] The effective volume is 1350m 3 For a blast furnace with a hearth diameter of 8.55 m, under the conditions of a slag-iron ratio of about 630 kg / t, a TiO2 content of about 22.9%, and a Ti content of 0.187% in molten iron, according to formula (1), if a, b, and c are 27, 0.52, and -0.19 and 28, 0.58, and -0.17 respectively, the standard wind speeds are 187.5 m / s and 190.8 m / s respectively.

[0052] In actual production, according to the existing technical document "Ironmaking Calculation Analysis", the actual air volume into the blast furnace is 2899m 3 / min, which is 470m lower than the air volume counted during production. 3 / min, pig iron production is about 3500-3600t / d, and the average Ti and Si contents of molten iron per 100 times are 0.246% and 0.209% respectively.2 Shrink to 0.2557m 2 Under the same other conditions, based on the calculated air volume, the standard air velocity was increased from 178.6 m / s to 189 m / s. Simultaneously, the charging system was adjusted as shown in Tables 3 and 4, with the overall charge shifted toward the center. The edge of the iron-containing charge landed 0.335 m from the furnace wall, and the edge of the coke landed 0.195 m from the furnace wall. Following these measures, the activity of the blast furnace hearth center increased. The furnace bottom center temperature, a key indicator of accumulation in the hearth center, gradually increased from 525°C to stabilize between 537 and 543°C. The blast furnace's smelting intensity increased, the smelting cycle was accelerated, and the furnace temperature was lowered. The Ti and Si contents of the molten iron decreased to 0.187% and 0.125%, respectively, with a difference of 0.062%. Daily pig iron production increased to 3,900 to 4,000 t / d.

[0053] Table 5: 1350m 3 Blast furnace charging system before adjustment

[0054] Table 6: 1350m 3 Blast furnace charging system after adjustment

[0055] In summary, the present invention's method for reducing hearth center accumulation during blast furnace smelting of high-titanium vanadium-titanium magnetite improves the activity of the hearth center and gradually increases the furnace bottom center temperature, a key indicator of hearth center accumulation. This indicates that accumulations rich in TiC, TiN, and their solid solution Ti(C,N) are not forming in the hearth. This results in increased blast furnace smelting intensity, faster smelting cycles, and lower furnace temperatures. The Ti and Si contents of the molten iron decrease with every 100 tappings, increasing the daily output of pig iron.

[0056] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope of the embodiments disclosed in the claims. Although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as plural unless expressly limited to the singular.

[0057] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples. Within the spirit of the embodiments of the present invention, the technical features of the above embodiments or different embodiments may be combined, and there are many other variations of different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the scope of protection of the embodiments of the present invention.

Claims

1. A method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite, characterized in that: The blast furnace is composed of the throat, body, waist, belly, hearth and bottom along its axis from top to bottom. A layer of radial tuyere is evenly distributed along the circumference of the blast furnace in the hearth. The accumulation in the center of the hearth can be reduced by adopting a reasonable air supply system and charging system, including: In the process of blast furnace smelting, formulate the air supply system: Determine the standard wind speed based on the slag-iron ratio, the TiO2 content in the slag and the Ti content in the molten iron; The actual air volume entering the blast furnace is calculated based on the standard wind speed; Compare the actual air volume entering the blast furnace with the air volume counted during production, and adjust the air inlet area and actual wind speed; During the blast furnace smelting process, a charging system is formulated: the distance between the edge of the iron-containing charge and the throat steel brick is 0.32-0.48m, the distance between the coke and the throat steel brick is 0.18-0.36m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

2. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that: The blast furnace has an effective volume of 1200m 3 And above blast furnace.

3. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that: The blast furnace has an effective volume of 1200m 3 、1350m 3 、1750m 3 and 2000m 3 blast furnace.

4. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that: Use 2 to 4 rings of material for loading, and ensure that the angle difference between the outer ring of the ore and the outer focus is controlled at -0.5 to -1.0°, and the angle difference between the inner ring of the ore and the inner focus is controlled at 5.5 to 6.0°.

5. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that: "Determine the standard wind speed based on the slag-iron ratio, the TiO2 content of the slag and the Ti content of the molten iron" according to the following formula (1): V = a × D h +b×R slag +c×(TiO2) / Ti (1) In formula (1), V is the standard wind speed, m / s; D h is the furnace diameter, m; R slag is the slag-iron ratio, kg / t; (TiO2) is the TiO2 content in the slag, %; Ti is the Ti content in the molten iron, %; a, b, c are coefficients, a is 27~28, b is -0.17~-0.19, and c is 0.52~0.

58.

6. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 5, characterized in that: The coefficients a, b and c in formula (1) can simultaneously take larger or smaller values ​​within the value range.

7. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 3, characterized in that: The effective volume is 1200m 3 For a blast furnace with a throat diameter of 6.0m, the distance from the edge of the iron-containing charge to the throat steel brick is 0.32-0.38m, the distance from the coke to the throat steel brick is 0.18-0.28m, and the distance from the edge of the coke to the furnace wall is smaller than that of the ore.

8. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 3, characterized in that: The effective volume is 1350m 3 The blast furnace has a throat diameter of 6.3m, the distance between the edge of the iron-containing charge and the throat steel brick is 0.33-0.40m, the distance between the coke and the throat steel brick is 0.19-0.30m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

9. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 3, characterized in that: The effective volume is 1750m 3 The blast furnace has a throat diameter of 6.9m, the distance between the edge of the iron-containing charge and the throat steel brick is 0.37-0.43m, the distance between the coke and the throat steel brick is 0.21-0.32m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

10. The method for reducing the accumulation in the center of the furnace during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 3, characterized in that: The effective volume is 2000m 3 The blast furnace has a throat diameter of 7.6m, the distance between the edge of the iron-containing charge and the throat steel brick is 0.40-0.48m, the distance between the coke and the throat steel brick is 0.23-0.36m, and the distance between the edge of the coke and the furnace wall is smaller than that of the ore.

Images