Blast furnace zero-pellet-ratio smelting method based on composite furnace charge structure

Abstract

The invention relates to the technical field of blast furnace smelting, in particular to a blast furnace zero-pellet-ratio smelting method based on a composite furnace charge structure, which comprises the following steps: (1) furnace charge preparation, (2) material distribution system adjustment, (3) air supply system adjustment, (4) slag composition adjustment and (5) furnace temperature control. By adopting the method, the problems of high cost, unstable supply, insufficient metallurgical performance collaboration and the like caused by dependence on pellets in the prior art can be solved, and on the premise of ensuring stable and smooth operation of the blast furnace, the production cost is reduced, and the smelting efficiency of the blast furnace is improved.

Description

Technical field

[0001] The present invention relates to the technical field of blast furnace smelting, and in particular to a blast furnace zero pellet ratio smelting method based on a composite charge structure. [Background Technology]

[0002] In traditional blast furnace smelting, pellets are typically used as a key charge, along with other charges such as sintered ore and lump ore. However, pellet production is costly, requires stringent raw materials, and is energy-intensive. In some cases, pellet supply may be limited. Furthermore, pellets undergo reduction expansion during blast furnace smelting, and their metallurgical properties exhibit poor synergy with other charges.

[0003] Therefore, exploring a blast furnace smelting method that does not use pellets is of great significance for reducing production costs and improving the flexibility and stability of blast furnace smelting. [Summary of the invention]

[0004] In view of the above, it is necessary to provide a blast furnace zero pellet ratio smelting method based on a composite charge structure, specifically an efficient smelting method that achieves zero pellet ratio by optimizing charge structure, distribution pattern and coordinated control of process parameters.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A blast furnace zero pellet ratio smelting method based on a composite charge structure, the method comprising the following steps:

[0007] (1) Charge preparation: 16-20% lump ore and 80-84% sintered ore are combined to obtain the charge;

[0008] (2) Adjustment of distribution system: adopt the precise distribution mode of center coke, with the distribution ratio of center coke being 15%-20% of the total coke volume, and the distribution ratio of edge coke being 25%-30% of the total coke volume, and the mineral coke being maintained at the same angle difference; the distribution matrix is gradually adjusted to P 38 3 36 3 34 2 32 2 30 2 34 1↓K 38 5 36 3 33 2 29.4 1 25.9 1 10 3 29.4 1↓. Where P is the ore system and K is the coke system.

[0009] Furthermore, in step (1), the mass proportion of lump ore is 20%, and the mass proportion of sintered ore is 80%.

[0010] Furthermore, the method also includes adjusting the air supply system, and the specific control parameters are as follows: a. The air volume is controlled at 5300-5500m 3 / min, the air supply ratio is controlled between 1.5-2.5; b. The air outlet area is controlled at 0.34m 2 ; c. The air outlet length is set to 680mm; d. The pressure difference is controlled between 170-180kPa; e. The kinetic energy of the blast is controlled between 140-150KJ / s.

[0011] Furthermore, the method also includes adjusting the slag composition, specifically adjusting the MgO / Al2O3 ratio in the slag to 0.45-0.50; wherein the MgO content is 7.0-7.5%, and the Al2O3 content is 15.5-16.5%.

[0012] Furthermore, the method also includes furnace temperature control, specifically controlling the blast furnace temperature to be stable, wherein the hot air temperature is ≥1180°C and the physical heat of the molten iron is 1490-1520°C.

[0013] Furthermore, the Si content in the molten iron is 0.25%-0.45%.

[0014] The present invention has at least the following beneficial effects:

[0015] 1. This application proposes a blast furnace zero pellet ratio smelting method based on a composite charge structure, which solves the problems of high cost, unstable supply and insufficient synergy of metallurgical properties caused by reliance on pellets in the existing technology. While completely eliminating pellets, it can also maintain the stability of the blast furnace, ensure the stable and smooth operation of the blast furnace, reduce production costs and improve the blast furnace smelting efficiency.

[0016] 2. This application reduces the cost of molten iron raw materials by innovatively adjusting the charge structure, adopting a zero-pellet ratio charge structure, and using a certain proportion of lump ore and sintered ore to form the ore batch. At the same time, for the new charge structure, the charge system, air supply system, slag alkalinity and composition are optimized, and the furnace temperature is strictly controlled to ensure that the blast furnace runs stably and smoothly under the condition of zero pellet ratio. Specifically, reasonable charge batch adjustment ensures the stability of smelting intensity; the charge system adjustment enables the formation of a reasonable soft melting zone in the furnace and optimizes the gas flow distribution; the air supply system adjustment ensures a reasonable initial gas flow and the activity of the furnace, and promotes the full progress of the reaction in the furnace; the adjustment of slag-related parameters ensures good separation characteristics of slag and iron and molten iron quality; stable furnace temperature control ensures the stability of the entire smelting process. Through the synergistic effect of the above measures, not only the production cost is reduced, but also the production efficiency and molten iron quality of the blast furnace are improved, bringing significant economic and social benefits to steel enterprises, and the effect brought by the synergistic effect of various parameters. [Specific implementation method]

[0017] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] Example 1:

[0019] This embodiment provides a blast furnace zero pellet ratio smelting method based on a composite charge structure, the method comprising the following steps:

[0020] (1) Charge preparation: The charge is prepared by combining 16% lump ore and 84% sintered ore. By adjusting the ratio of lump ore to sintered ore, the metallurgical properties of the charge are ensured to meet the requirements of blast furnace smelting. By adjusting the ore batch and coke batch, the indirect reduction of the ore is promoted while ensuring the output, and the utilization rate of coal gas is improved.

[0021] (2) Adjustment of the charging system: A precise charging mode of center coke addition is adopted, with the center coke charging ratio being 15% of the total coke volume, and the edge coke charging ratio being 25% of the total coke volume, with the mineral coke maintained at the same angle difference; with smooth center airflow and stable edge airflow, a reasonable "platform + funnel" charging surface is formed. By adjusting the charging angle and coke distribution, the blast furnace can form an ideal soft melting zone shape under the zero pellet ratio charge structure. Center coke addition can enhance the center airflow, improve the charge surface stability, and promote the improvement of coal gas utilization; stable edge load can stabilize the edge airflow, protect the furnace wall, and prevent the charge from adhering to the furnace wall. The charging ratio of center coke and edge coke and the charging angle difference range are determined through production practice. Within this range, a stable and reasonable soft melting zone can be formed, maintaining the long-term stable and smooth operation of the blast furnace. Under the condition of using a zero pellet ratio charge structure, the pressure and volume relationship in the furnace is tense when the charge structure changes significantly. If it is not adjusted, the smooth operation of the furnace will be destroyed and various economic and technical indicators will decline. In order to ensure the smooth flow, two airflows need to be released. The operation adopts the method of increasing the number of coke circles at the edge and center to ensure the reasonable distribution of coal gas flow in the blast furnace under the zero pellet ratio charge structure. The distribution matrix is gradually adjusted to P 38 3 36 3 34 2 32 2 30 2 34 1↓K 38 5 36 3 33 2 29.4 1 25.9 1 10 3 29.4 1↓;

[0022] (3) Adjustment of air supply system: a. Air volume is controlled at 5300m 3 / min, the air supply ratio is controlled between 1.5; b. The air outlet area is controlled at 0.34m 2 ; c. The length of the tuyere is set to 680mm; d. The pressure difference is controlled within 170kPa; e. The blast kinetic energy is controlled within 140KJ / s; adjust the blast furnace air supply system, appropriately adjust the tuyere length and stabilize the air volume, strictly manage the pressure difference, increase the blast kinetic energy, and ensure the activity of the furnace. A reasonable air supply system is conducive to the reasonable distribution of the initial coal gas flow in the blast furnace, promotes the stable and smooth operation of the blast furnace and improves the utilization rate of the blast furnace gas. Maintaining a large air volume can increase the coal gas flow rate in the furnace and strengthen the heat and mass transfer process in the furnace; strictly controlling the pressure difference can ensure the stability of the air flow in the furnace; increasing the blast kinetic energy, ensuring the activity of the furnace, and promoting uniform reaction in the furnace;

[0023] (4) Adjust slag basicity: binary basicity is controlled at 1.20-1.30, and ternary basicity is controlled at 1.45-1.55. Accurately control slag basicity, optimize slag properties, ensure good separation of slag and molten iron, and improve molten iron quality. The adjustment range of slag basicity is determined by theoretical calculation and physical sampling, ensuring that the charge structure is adjusted in a timely manner according to the changes in sintering and lump ore composition under a zero pellet ratio charge structure to meet the requirements of the slag making system.

[0024] (5) Slag composition adjustment: Adjust the MgO / Al2O3 ratio in the slag to 0.47; among them, the MgO content is 7.0% and the Al2O3 content is 15.5%; ensure that the slag has good fluidity under the zero pellet ratio charge structure, avoid slag adhesion, and ensure smooth discharge of slag and iron. The appropriate MgO / Al2O3 ratio can effectively improve the physical and chemical properties of the slag. If the MgO content is too low, the slag fluidity and stability are poor; if it is too high, the slag volume will increase. When the Al2O3 content is within a certain range and the slag magnesium-aluminum ratio is well controlled, the slag can maintain good fluidity at the blast furnace smelting temperature and ensure smooth separation and discharge of slag and iron.

[0025] (6) Furnace temperature control: The blast furnace temperature is kept stable, wherein the hot air temperature is ≥1180°C, the physical heat of the molten iron is 1490°C, and the Si content in the molten iron is 0.25%. Stable furnace temperature is the key to normal blast furnace smelting. Appropriate hot air temperature, physical heat of the molten iron, and Si content in the molten iron can ensure the smooth progress of the chemical reaction in the furnace and ensure the stability of the molten iron quality.

[0026] Example 2:

[0027] This embodiment provides a blast furnace zero pellet ratio smelting method based on a composite charge structure, the method comprising the following steps:

[0028] (1) Charge preparation: 20% lump ore and 80% sintered ore are combined to obtain the charge; by adjusting the ratio of lump ore and sintered ore, the metallurgical properties of the charge are ensured to meet the requirements of blast furnace smelting. By adjusting the ore batch and coke batch, the indirect reduction of the ore is promoted while ensuring the output, and the gas utilization rate is improved;

[0029] (2) Adjustment of the charging system: A precise charging mode of center coke addition is adopted, with the center coke charging ratio being 18% of the total coke volume, and the edge coke charging ratio being 28% of the total coke volume, with the mineral coke maintained at the same angle difference; with smooth center airflow and stable edge airflow, a reasonable "platform + funnel" charging surface is formed. By adjusting the charging angle and coke distribution, the blast furnace can form an ideal soft melting zone shape under the zero pellet ratio charge structure. Center coke addition can enhance the center airflow, improve the stability of the charge surface, and promote the improvement of coal gas utilization; stable edge load can stabilize the edge airflow, protect the furnace wall, and prevent the charge from adhering to the furnace wall. The charging ratio of center coke and edge coke and the charging angle difference range are determined through production practice. Within this range, a stable and reasonable soft melting zone can be formed, maintaining the long-term stable and smooth operation of the blast furnace. Under the condition of using a zero pellet ratio charge structure, the pressure and volume relationship in the furnace is tense when the charge structure changes significantly. If it is not adjusted, the smooth operation of the furnace will be destroyed and various economic and technical indicators will decline. In order to ensure the smooth flow, two airflows need to be released. The operation adopts the method of increasing the number of coke circles at the edge and center to ensure the reasonable distribution of coal gas flow in the blast furnace under the zero pellet ratio charge structure. The distribution matrix is gradually adjusted to P 38 3 36 3 34 2 32 2 30 2 34 1↓K 38 5 36 3 33 2 29.4 1 25.9 1 10 3 29.4 1↓;

[0030] (3) Adjustment of air supply system: a. Air volume is controlled at 5400m 3 / min, the air supply ratio is controlled between 2.0; b. The air outlet area is controlled at 0.34m 2 ; c. The length of the tuyere is set to 680mm; d. The pressure difference is controlled within 175kPa; e. The blast kinetic energy is controlled within 145KJ / s; adjust the blast furnace air supply system, appropriately adjust the tuyere length and stabilize the air volume, strictly manage the pressure difference, increase the blast kinetic energy, and ensure the activity of the furnace. A reasonable air supply system is conducive to the reasonable distribution of the initial coal gas flow in the blast furnace, promotes the stable and smooth operation of the blast furnace and improves the utilization rate of the blast furnace gas. Maintaining a large air volume can increase the coal gas flow rate in the furnace and strengthen the heat and mass transfer process in the furnace; strictly controlling the pressure difference can ensure the stability of the air flow in the furnace; increasing the blast kinetic energy, ensuring the activity of the furnace, and promoting uniform reaction in the furnace;

[0031] (4) Adjust slag basicity: binary basicity is controlled at 1.20-1.30, and ternary basicity is controlled at 1.45-1.55. Accurately control slag basicity, optimize slag properties, ensure good separation of slag and molten iron, and improve molten iron quality. The adjustment range of slag basicity is determined by theoretical calculation and physical sampling, ensuring that the charge structure is adjusted in a timely manner according to the changes in sintering and lump ore composition under a zero pellet ratio charge structure to meet the requirements of the slag making system.

[0032] (5) Slag composition adjustment: Adjust the MgO / Al2O3 ratio in the slag to 0.45; among them, the MgO content is 7.1% and the Al2O3 content is 15.9%; ensure that the slag has good fluidity under the zero pellet ratio charge structure, avoid slag adhesion, and ensure smooth discharge of slag and iron. The appropriate MgO / Al2O3 ratio can effectively improve the physical and chemical properties of the slag. If the MgO content is too low, the slag fluidity and stability are poor; if it is too high, the slag volume will increase. When the Al2O3 content is within a certain range and the slag magnesium-aluminum ratio is well controlled, the slag can maintain good fluidity at the blast furnace smelting temperature and ensure smooth separation and discharge of slag and iron.

[0033] (6) Furnace temperature control: The blast furnace temperature is kept stable, wherein the hot air temperature is ≥1180°C, the physical heat of the molten iron is 1500°C, and the Si content in the molten iron is 0.35%. Stable furnace temperature is the key to normal blast furnace smelting. Appropriate hot air temperature, physical heat of the molten iron, and Si content in the molten iron can ensure the smooth progress of the chemical reaction in the furnace and ensure the stability of the molten iron quality.

[0034] Example 3:

[0035] This embodiment provides a blast furnace zero pellet ratio smelting method based on a composite charge structure, the method comprising the following steps:

[0036] (1) Charge preparation: The charge is prepared by combining 16% lump ore and 84% sintered ore. By adjusting the ratio of lump ore to sintered ore, the metallurgical properties of the charge are ensured to meet the requirements of blast furnace smelting. By adjusting the ore batch and coke batch, the indirect reduction of the ore is promoted while ensuring the output, and the utilization rate of coal gas is improved.

[0037] (2) Adjustment of the charging system: A precise charging mode of center coke is adopted, with the center coke charging ratio being 20% of the total coke volume, and the edge coke charging ratio being 30% of the total coke volume, with the mineral coke maintained at the same angle difference; with smooth center airflow and stable edge airflow, a reasonable "platform + funnel" charging surface is formed. By adjusting the charging angle and coke distribution, the blast furnace can form an ideal soft melting zone shape under the zero pellet ratio charge structure. Center coke can enhance the center airflow, improve the charge surface stability, and promote the improvement of coal gas utilization; stable edge load can stabilize the edge airflow, protect the furnace wall, and prevent the charge from adhering to the furnace wall. The charging ratio of center coke and edge coke and the charging angle difference range are determined through production practice. Within this range, a stable and reasonable soft melting zone can be formed, maintaining the long-term stable and smooth operation of the blast furnace. Under the condition of using a zero pellet ratio charge structure, the pressure and volume relationship in the furnace is tense when the charge structure changes significantly. If it is not adjusted, the smooth operation of the furnace will be destroyed and various economic and technical indicators will decline. In order to ensure the smooth flow, two airflows need to be released. The operation adopts the method of increasing the number of coke circles at the edge and center to ensure the reasonable distribution of coal gas flow in the blast furnace under the zero pellet ratio charge structure. The distribution matrix is gradually adjusted to P 38 3 36 3 34 2 32 2 30 2 34 1↓K 38 5 36 3 33 2 29.4 1 25.9 1 10 3 29.4 1↓;

[0038] (3) Adjustment of air supply system: a. Air volume is controlled at 5500m 3 / min, the air supply ratio is controlled at 2.5; b. The air outlet area is controlled at 0.34m 2 ; c. The length of the tuyere is set to 680mm; d. The pressure difference is controlled at 180kPa; e. The blast kinetic energy is controlled at 150KJ / s; adjust the blast furnace air supply system, appropriately adjust the tuyere length and stabilize the air volume, strictly manage the pressure difference, increase the blast kinetic energy, and ensure the activity of the furnace. A reasonable air supply system is conducive to the reasonable distribution of the initial coal gas flow in the blast furnace, promotes the stable and smooth operation of the blast furnace and improves the utilization rate of the blast furnace gas. Maintaining a large air volume can increase the coal gas flow rate in the furnace and strengthen the heat and mass transfer process in the furnace; strictly controlling the pressure difference can ensure the stability of the air flow in the furnace; increasing the blast kinetic energy, ensuring the activity of the furnace, and promoting uniform reaction in the furnace;

[0039] (4) Adjust slag basicity: binary basicity is controlled at 1.20-1.30, and ternary basicity is controlled at 1.45-1.55. Accurately control slag basicity, optimize slag properties, ensure good separation of slag and molten iron, and improve molten iron quality. The adjustment range of slag basicity is determined by theoretical calculation and physical sampling, ensuring that the charge structure is adjusted in a timely manner according to the changes in sintering and lump ore composition under a zero pellet ratio charge structure to meet the requirements of the slag making system.

[0040] (5) Slag composition adjustment: Adjust the MgO / Al2O3 ratio in the slag to 0.45-0.50; among which, the MgO content is 7.5% and the Al2O3 content is 16.5%; ensure that the slag has good fluidity under the zero pellet ratio charge structure, avoid slag adhesion, and ensure smooth discharge of slag and iron. The appropriate MgO / Al2O3 ratio can effectively improve the physical and chemical properties of the slag. If the MgO content is too low, the slag fluidity and stability are poor; if it is too high, the slag volume will increase. When the Al2O3 content is within a certain range and the slag magnesium-aluminum ratio is well controlled, the slag can maintain good fluidity at the blast furnace smelting temperature and ensure smooth separation and discharge of slag and iron.

[0041] (6) Furnace temperature control: Control the blast furnace temperature to be stable, wherein the hot air temperature is ≥1180℃, the physical heat of molten iron is 1520℃; the Si content in the molten iron is 0.45%; stable furnace temperature is the key to normal smelting in the blast furnace, and appropriate hot air temperature, physical heat of molten iron and Si content in the molten iron can ensure the smooth progress of chemical reactions in the furnace and ensure the stability of molten iron quality.

[0042] The compositions of the sintered ore and lump ore used in Examples 1-3 are shown in Table 1.

[0043] Table 1 Main indicators of sintered ore and lump ore used (%)

[0044]

[0045] Implementation effect: According to the method of Example 2 (after implementation) of this application, 2650m 3 The blast furnace operated smoothly under the zero pellet ratio charge structure, with daily output remaining above 7,600 tons, maintaining high efficiency and low consumption. The average smelting results over three months of production were compared with those before the implementation (using a conventional pellet-containing charge structure and conventional charge distribution system) as shown in Table 2:

[0046] Table 2 Improvement effect of the embodiment

[0047]

[0048] The zero-pellet ratio smelting method of the present invention can effectively reduce production costs, improve resource utilization, and maintain long-term stable and smooth operation of the blast furnace without using pellets. Compared with previous smelting methods, the present invention has significant economic and social benefits and broad application prospects.

[0049] However, the applicant also found that the use of zero pellet ratio charge structure will reduce the overall grade of the furnace, resulting in an increase in the slag ratio. The experiment found that adjusting the charge distribution system can eliminate the above effects. Specifically, the original charge distribution matrix of the blast furnace before implementation is P 38 3 36 3 34 3 32 2 30 2↓K 38 4 36 3 33 2 29.4 1 25.9 1 10 2 29.4 1↓ (traditional fabric system) and the fabric matrix P of Example 2 of this application after implementation 38 3 36 3 34 2 32 2 30 2 34 1↓K 38 5 36 3 33 2 29.4 1 25.9 1 10 3 29.4 The effect of 1↓ on slag ratio is shown in Table 3:

[0050] Table 3 Operation system under different charge structure conditions

[0051]

[0052] In actual operation, the applicant found that if the charge structure with a pellet ratio of 0 is adopted after implementation, if the charge distribution system is not adjusted, it will lead to a tense relationship between the blast furnace pressure and the amount, and there will be some precursors of unstable furnace conditions. Therefore, in actual operation, the applicant adjusted the charge distribution system to the charge distribution system used in the embodiment of the present application. Combined with the test results in Table 3, it can be seen that using the charge distribution system of the present application, when the slag ratio increases (due to the removal of pellets, the overall blast furnace charging grade decreases and the slag ratio increases), the fuel ratio can be maintained at a low level, which can reduce production costs and optimize energy efficiency, indicating that the present application has outstanding practical significance. In summary, the scheme of the present application can reduce production costs and environmental protection costs.

[0053] While the descriptions of several embodiments of the present invention are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and such modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A blast furnace zero pellet ratio smelting method based on a composite charge structure, characterized in that: The method comprises the following steps: (1) Charge preparation: 16-20% lump ore and 80-84% sintered ore are combined to obtain the charge; (2) Adjustment of distribution system: adopt the precise distribution mode of center coke, with the distribution ratio of center coke being 15%-20% of the total coke volume, and the distribution ratio of edge coke being 25%-30% of the total coke volume, and the mineral coke being maintained at the same angle difference; the distribution matrix is gradually adjusted to P 38 3 36 3 34 2 32 2 30 2 34 1↓K 38 5 36 3 33 2 29.4 1 25.9 1 10 3 29.4 1↓.

2. The method according to claim 1, characterized in that The mass proportion of the lump ore in step (1) is 20%, and the mass proportion of the sintered ore is 80%.

3. The method according to claim 1, characterized in that The method also includes adjusting the air supply system. The specific control parameters are as follows: a. The air volume is controlled at 5300-5500m 3 / min, the air supply ratio is controlled between 1.5-2.5; b. The air outlet area is controlled at 0.34m 2 ; c. The air outlet length is set to 680mm; d. The pressure difference is controlled between 170-180kPa; e. The kinetic energy of the blast is controlled between 140-150KJ / s.

4. The method according to claim 1, wherein The method further includes adjusting the slag composition, specifically adjusting the ratio of MgO / Al2O3 in the slag to 0.45-0.

50.

5. The method according to claim 1, wherein The method also includes furnace temperature control, specifically controlling the blast furnace temperature to be stable, wherein the hot air temperature is ≥1180°C and the physical heat of the molten iron is 1490-1520°C.

6. The method according to claim 5, characterized in that The Si content in the molten iron is 0.25%-0.45%.

Images