Method for maintaining stability of blast furnace hearth

Abstract

The invention discloses a method for maintaining the stability of a blast furnace hearth, which comprises the following steps of: distributing materials for each gear by adopting a material distribution chute, and the number of turns when the material distribution chute distributes the materials for each gear from the eleventh gear to the first gear is O0003332,000 C0022222,000 or O0002332,000 C00222222,100 in sequence, or the number of turns when the material distribution chute distributes the materials for each gear from the eleventh gear to the first gear; wherein C represents coke, and O represents ore. According to the method, firstly, the center coke adding amount is increased by reducing the number of ore distribution turns of the fourth gear or canceling the inner ring gear and properly prolonging the coke distribution time, so that stability of center gas flow is kept, and meanwhile replacement of pulverized coke of a dead stock column is accelerated; secondly, the ore-coke ratio of the edge is adjusted to be suitable for the characteristic of high cooling strength of the copper cooling wall; and finally, the ore batch is properly reduced, the ore-coke ratio of the middle ring belt is reduced, and the stability of the pressure difference in the furnace is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of blast furnaces, and in particular to a method for maintaining a stable hearth of a blast furnace. Background Art

[0002] The hearth and bottom of a blast furnace are immersed in liquid slag during production and are in a high-temperature, high-pressure smelting state for a long time. The resulting mechanical and chemical corrosion seriously threatens the safe production of the blast furnace and is one of the key parts for the longevity of the blast furnace.

[0003] The existing methods for extending the life of blast furnace hearth are only theoretical guidance and do not directly reflect the 2500m 3 How to operate during the smelting process of a high-grade blast furnace to achieve the goal of increasing the life of the blast furnace hearth. Although different blast furnaces have certain commonalities, they also have their own characteristics, and the applicable methods of different blast furnaces cannot be directly referenced.

[0004] With the continuous intensification of blast furnace smelting, maintaining the safe and stable operation of the blast furnace hearth has become a prominent problem that needs to be urgently solved in ironmaking production. It is particularly necessary to maintain the stable operation of the blast furnace and extend its life. Summary of the invention

[0005] The object of the present invention is to provide a method for maintaining a stable blast furnace hearth, thereby improving the stability of blast furnace operation and facilitating prolonging the life of the blast furnace.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a method for maintaining stability of a blast furnace hearth, comprising: dividing the throat of the blast furnace into 11 equal parts with equal areas and coaxially arranged, and sequentially numbering the parts into 11 gears, 10 gears, 9 gears, 8 gears, 7 gears, 6 gears, 5 gears, 4 gears, 3 gears, 2 gears and 1 gear in a direction away from the furnace wall of the blast furnace, and using a material distribution chute to distribute materials to each gear, and the number of circles of the material distribution chute when distributing materials at each gear from the 11th gear to the 1st gear is: O00033320000C00222222000 or O00023320000C00222222100;

[0008] Among them, C stands for coke and O stands for ore.

[0009] In an optional embodiment, the blast furnace is 2500m 3 blast furnace.

[0010] In an optional embodiment, the 4th gear focusing angle is 31-31.3°, the focusing time is 89-91 seconds, the material line is 1.3-1.4 m, and the ore batch is 73-74 t.

[0011] In an optional embodiment, the method satisfies at least one of the following af:

[0012] a. The average particle size of the coke is 45-48 mm, and the particle size of the coke is 45-48 mm, accounting for > 55 wt%;

[0013] b. The blast furnace coal ratio is 160-170kg / t;

[0014] c. The blast furnace load is 4.9t / t or more;

[0015] d. the blast furnace slag ratio is less than 335kg / t;

[0016] e. The blast furnace charging grade is 57% or more;

[0017] f. The blast furnace pressure difference is 155-160kPa.

[0018] In an optional embodiment, when the edge airflow is overdeveloped, the ore distribution is increased and the coke distribution is reduced at the edge, while the coke distribution is increased in the center, thereby increasing the ore and coke loads at the edge positions and reducing the ore and coke loads at the center positions.

[0019] In an optional embodiment, when the central airflow is overdeveloped, the ore distribution at the edge is reduced and the coke distribution is increased, thereby reducing the ore and coke loads at the edge positions.

[0020] In an optional embodiment, the discharge flow rate Q = T / (β×P); wherein T is the total weight of the charge, β is the total number of revolutions of the charge chute at each gear level, and P represents the time required for the charge chute to make one circle around the center of the blast furnace, in units of S.

[0021] In an optional embodiment, the distribution time of the distribution chute at a specified gear is P×m±N seconds, wherein m is the number of revolutions when distributing a batch of coke or ore at the specified gear, and 0≤N≤5.

[0022] In an optional embodiment, when blowby causes the temperature of the cold surface of the furnace cooling wall to rise abnormally, a grouting hole is drilled between two cooling walls in the area with the highest heat flux intensity or the highest temperature and grouting is performed, wherein the heat flux intensity is the heat flow rate passing through a unit area per unit time.

[0023] In an optional embodiment, if the temperature at a part of the furnace increases abnormally, 1-2 air vents in the direction of the abnormally increased temperature are blocked, and the coal withdrawal ratio is 10-15kg / t, and the top pressure is 5-10kpa.

[0024] The present invention has the following beneficial effects:

[0025] The implementation mode of the present invention firstly increases the amount of coke added in the center by reducing the number of 4th gear ore distribution circles or canceling the inner ring gear and appropriately extending the coke distribution time, with the purpose of maintaining the stability of the central coal gas flow and accelerating the replacement of pulverized coke in the dead material column; secondly, adjusts the ore-coke ratio at the edge, loosens the edge to reduce the scouring of the cooling wall by the local airflow, and is suitable for the high cooling intensity of the copper cooling wall; finally, appropriately reduces the ore batch and reduces the ore-coke ratio of the middle ring, which is beneficial to the stability of the pressure difference in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 The charging system implemented in Example 1;

[0028] Figure 2 The charging system implemented in Example 2;

[0029] Figure 3 This is the charging system implemented in Comparative Example 1. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] The embodiment of the present invention provides a method for maintaining stability of a blast furnace hearth, comprising: dividing the throat of the blast furnace into 11 equal parts with equal areas and coaxially arranged, and sequentially numbering them into 11 gears, 10 gears, 9 gears, 8 gears, 7 gears, 6 gears, 5 gears, 4 gears, 3 gears, 2 gears and 1 gear in the direction away from the furnace wall of the blast furnace, and using a distribution chute to distribute materials to each gear, and the number of circles of the distribution chute when distributing materials at each gear from the 11th gear to the 1st gear is: O00033320000C00222222000 or O00023320000C00222222100;

[0032] Among them, C stands for coke and O stands for ore.

[0033] In the present application, the blast furnace throat is divided into 11 equal parts of equal area and coaxially arranged and numbered accordingly, that is, gear 1 is a circular area located in the center of the blast furnace, gears 2-11 are annular areas concentric with gear 1, gear 2 is adjacent to gear 1, and gear 11 is close to the blast furnace wall. The specific charging system during distribution is O00033320000C00222222000 or O00023320000C00222222100, so as to realize the ratio of the weight of ore coke in the radial direction of the blast furnace and achieve the purpose of distributing the gas flow.

[0034] When the charging system is O00033320000C00222222000: the number of circles made by the distribution chute when distributing ore at each gear position from 11 gear to 1 gear is 0, 0, 0, 3, 3, 3, 2, 0, 0, 0 and 0 respectively, that is, no ore is distributed at gears 9-11 and 1-4; the number of circles made by the distribution chute when distributing coke at each gear position from 11 gear to 1 gear is 0, 0, 2, 2, 2, 2, 2, 2, 0, 0 and 0 respectively, that is, no coke is distributed at gears 10, 11 and 1-3; When the charging system is O00023320000C00222222100: the number of circles made by the distribution chute when distributing ore at each gear from 11 gear to 1 gear is 0, 0, 0, 2, 3, 3, 2, 0, 0, 0 and 0 respectively, that is, no ore is distributed at gears 9-11 and 1-4; the number of circles made by the distribution chute when distributing coke at each gear from 11 gear to 1 gear is 0, 0, 2, 2, 2, 2, 2, 2, 1, 0 and 0 respectively, that is, no coke is distributed at gears 10, 11 and gears 1 and 2.

[0035] The implementation mode of the present invention firstly increases the amount of coke added in the center by reducing the number of 4th gear ore distribution circles or canceling the inner ring gear and appropriately extending the coke distribution time, with the purpose of maintaining the stability of the central coal gas flow and accelerating the replacement of pulverized coke in the dead material column; secondly, reduces the ore-to-coke ratio at the edge, loosens the edge to reduce the scouring of the cooling wall by the local airflow, and is suitable for the high cooling intensity of the copper cooling wall; finally, appropriately reduces the ore batch and reduces the ore-to-coke ratio of the middle ring, which is beneficial to the stability of the pressure difference in the furnace.

[0036] In an optional embodiment, the blast furnace is 2500m 3 blast furnace.

[0037] In an optional embodiment, the 4th gear focusing angle is 31-31.3°, the focusing time is 89-91 seconds, the material line is 1.3-1.4 m, and the ore batch is 73-74 t.

[0038] The present application can achieve stable and smooth furnace conditions under high pressure difference conditions. The airflow in the furnace changes after the pressure difference increases. Therefore, while adjusting the charging system, the 4th gear coking angle is expanded from 30.8° to 31-31.3° to stabilize the central airflow, and the coking time is stabilized at about 90 seconds to match the distribution matrix. To avoid fluctuations in furnace conditions, the material line is raised from 1.5m to about 1.4m, and the ore batch is expanded from 69t to about 74t. The gas utilization rate of the entire load regulation process is steadily increased and stabilized, reaching a maximum of 49.6%. The material surface of "platform + funnel" is formed, which improves the air permeability, reduces the pressure difference, and eliminates the influence of the high pressure difference on the furnace.

[0039] In an optional embodiment, the method satisfies at least one of the following af:

[0040] a. The average particle size of the coke is 45-48 mm, and the particle size of the coke is 45-48 mm, accounting for > 55 wt%;

[0041] b. The blast furnace coal ratio is 160-170kg / t;

[0042] c. The blast furnace load is 4.9t / t or more;

[0043] d. the blast furnace slag ratio is less than 335kg / t;

[0044] e. The blast furnace charging grade is 57% or more;

[0045] f. The blast furnace pressure difference is 155-160kPa.

[0046] Currently, 2500m 3 Blast furnaces began to use 7m coke with better performance. The improvement of its hot strength, the application of new cantilever ceramic coke screen under the trough and the classification of coke into the furnace, as well as the increase in coal ratio, made the coke skeleton more prominent. The key to high coal ratio operation is to reduce the amount of coke powder in the dead material pile in the furnace and maintain sufficient porosity. Therefore, it is necessary not only to have sufficient hot strength, but also to ensure the appropriate average particle size of coke and a narrow particle size distribution. When the quality of coke deteriorates and the reactivity increases, large coke is more conducive to keeping the coke block intact because the dissolution reaction tends to the surface. Slag ratio is another factor that limits high coal ratio. At present, the blast furnace with high coal ratio can reach 57% in grade, and the slag ratio is generally less than 335kg / t. In the process of charging, the best quality coke and coke with larger particle size are consciously loaded at the end of a batch of coke through the charging sequence, which is conducive to the inner ring in the center of the blast furnace when charging.

[0047] Adjustment of the charging system is conducive to the control of pressure difference. Affected by the furnace type and basic operating system, 2500m 3The pressure difference level of the blast furnace is maintained at 160-165kPa for a long time. When the coal ratio is about 165kg / t and the load is above 4.9t / t, the pressure difference increases, which hinders the smooth entry of the charge into the furnace, resulting in poor material discharge, which may cause abnormal furnace conditions such as suspended material, and thus affect the normal production rhythm of the blast furnace; it is not conducive to the reasonable distribution of coal gas in the furnace, affecting the utilization efficiency of coal gas, which may lead to increased energy consumption, and at the same time have an adverse effect on the heat transfer of the furnace; the furnace is subjected to greater static pressure and shear force and the buoyancy caused by liquid iron, which will lead to premature crushing and damage of the furnace lining in the long run. For a long time, the pressure difference and forward movement have been viewed in opposition, and every effort has been made to reduce the pressure difference. Measures such as increasing the top pressure (from 220kPa to 234kPa) and strengthening the screening of raw materials have been taken, but the reduction is limited. Moreover, due to the limitation of the fan capacity, it is not allowed to increase the top pressure to ensure sufficient air volume. The application can achieve stable forward movement of the furnace condition under high pressure difference conditions.

[0048] In an optional embodiment, when the edge airflow is overdeveloped, the ore distribution is increased and the coke distribution is reduced at the edge, while the coke distribution is increased in the center, thereby increasing the ore and coke loads at the edge positions and reducing the ore and coke loads at the center positions.

[0049] In an optional embodiment, when the central airflow is overdeveloped, the ore distribution at the edge is reduced and the coke distribution is increased, thereby reducing the ore and coke loads at the edge positions.

[0050] The weight of ore or coke in a batch of charge is limited. When the weight of ore or coke at the edge is increased during charge distribution, the amount of ore or coke at other gears will decrease. Similarly, if the weight of ore or coke at the edge is reduced, the amount of ore or coke at other gears will increase. According to the air permeability characteristics of ore and coke in the furnace (the air permeability ratio of ore to coke is 1:13), the thickness of the coke window is controlled by coke distribution time and coke distribution gear, and daily airflow is fine-tuned in combination with the ore and coke load at each gear in the distribution, the upper gas distribution is corrected, the furnace condition is stabilized, and the gas utilization is improved, so as to keep the blast furnace stable and smooth for a long time. When the raw material and fuel conditions are good and meet the requirements of the furnace entry outline, resulting in excessive development of the edge coal gas flow, the number and weight of the ore circles at the edge gear can be increased and the weight of the coke at the center gear can be increased to achieve more ore and less coke at the edge and more coke in the center, increase the ore and coke loads at the edge gear, lighten the ore and coke loads at the center gear, and appropriately develop the center airflow; when the raw material and fuel conditions deteriorate, or the center airflow needs to be suppressed, then less ore and more coke should be distributed at the edge to reduce the ore and coke loads at the edge gear, and the blast furnace needs to appropriately develop the edge coal gas flow.

[0051] In an optional embodiment, the discharge flow rate Q = T / (β×P); wherein T is the total weight of the charge, β is the total number of revolutions of the charge chute at each gear level, and P represents the time required for the charge chute to make one circle around the center of the blast furnace, in units of S.

[0052] In an optional embodiment, the distribution time of the distribution chute at a specified gear is P×m±N seconds, wherein m is the number of revolutions when distributing a batch of coke or ore at the specified gear, and 0≤N≤5.

[0053] 2500m 3 The blast furnace charge matrix uses the time charge method, that is, the weight T of a batch of charge is certain. According to the total number of matrix circles β, the charge flow Q=T / (β×P) is calculated. In some implementations, P can be 7.5 seconds, and then the opening γ of the discharge gate is calculated according to the charge flow Q and the charge flow curve table. If n turns of charge are laid at a certain inclination angle α, the chute will change to another inclination angle position for charge laying after 7.5×n seconds. In production practice, the charge is laid according to the set charge time P×m±N seconds, and the N value is fine-tuned between 0-5 according to the furnace condition, airflow distribution, and raw material conditions. In the implementation mode of the present invention, the time method is reasonably used to fine-tune the charge time when the number of charge circles remains unchanged, and the central coke amount is adjusted in a timely and appropriate manner. That is, when the furnace condition deteriorates, the coke laying time is extended to adjust the ore-coke ratio to promote smooth operation, and when the furnace condition is stable, the coke laying time is shortened to make the central fire column slender and powerful, which is beneficial to improve the gas distribution.

[0054] In an optional embodiment, when the blowby gas causes the temperature of the cold surface of the furnace cylinder cooling wall to rise abnormally, a grouting hole is drilled between two cooling walls in the area with the highest heat flux intensity or the highest temperature, and grouting is performed, wherein the heat flux intensity is the heat flow rate passing through a unit area per unit time, and the heat flux intensity = cooling wall water temperature difference * cooling wall water flow / cooling wall area, which reflects the heat load borne by the cooling wall.

[0055] If the temperature of the cold surface of the furnace cooling wall rises abnormally due to blowby, it should be promptly and scientifically grouting and plugging should be carried out: In the past, for areas with high cooling wall temperature, the reserved grouting holes were grouted when the wind was off. Since the reserved grouting holes may not be the gas-blowing gaps flushed by gas, it is difficult for the grouting material to effectively fill the gas-blowing gaps flushed by gas; then the heat flux intensity is analyzed, and the location with higher heat flux intensity is determined according to the heat flux intensity of the cooling wall, or the high temperature of the furnace shell is measured by a new infrared thermometer, which is usually the location of gas leakage. For potential leakage areas, choose the joint between two cooling walls where the heat flux intensity is higher or the temperature measured by the infrared thermometer is higher. Do not damage the cooling wall, re-drill holes at fixed points to form new grouting holes, and block the gas outlet more directly to block the gas leakage route to the greatest extent to protect the furnace. The grouting material should be consistent with the refractory material of the cooling wall. The grouting pressure should be controlled within 70%-80% of the furnace pressure. If it is too high, it may penetrate the weak brick lining of the cooling wall and cause damage. If it is too low, the grouting will not go in due to resistance.

[0056] In an optional embodiment, if the temperature at a part of the furnace increases abnormally, 1-2 air vents in the direction of the abnormally increased temperature are blocked, and the coal withdrawal ratio is 10-15kg / t, and the top pressure is 5-10kpa.

[0057] For example, 2500m 3 At tk0802(150) of the carbon brick side wall of the 2# iron mouth hearth of the blast furnace (10# furnace) (hearth height 0.8m, thermocouple insertion depth 150mm), the temperature rises to 569℃, and the iron mouth depth is required to be ≥3200mm. Clean slag and iron are discharged from each furnace, and vanadium-titanium taphole mud is used to block the iron mouth, achieving the effect of protecting the furnace. When the carbon brick side wall tk0802(150) of the 2# iron mouth hearth reaches up to 1100℃, 1-2 air vents above this direction are blocked to maintain the principle of constant wind speed, with a coal withdrawal ratio of 10-15kg / t and a top pressure of 5-10kpa to ensure strong central airflow, reduce the dead material column in the hearth, improve the air and liquid permeability of the hearth, slow down the circulation of molten iron, and thus the furnace core temperature gradually decreases and tends to be stable, which is beneficial to the longevity of the blast furnace.

[0058] The implementation method of the present invention controls the thickness of the coke window by coking time and coking gear, and fine-tunes the ore and coke loads of each gear on a daily basis to maintain the central dominant airflow and maintain the long-term smooth operation of the blast furnace; scientifically uses the online grouting method to block the gas blowby parts; and adopts vanadium-titanium taphole mud and necessary tuyere blocking and furnace protection measures to address the rising temperature of the hot surface of the furnace. After adopting the above methods, the water temperature difference of each section of the blast furnace, the wall temperature of the cooling wall and the heat flux intensity are within the specified controllable range, and the smelting strength of the blast furnace is not significantly reduced.

[0059] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0060] Example 1

[0061] This embodiment provides a 2500m 3 The method for maintaining a stable blast furnace hearth comprises: a charging system of O00033320000C00222222000 (specifically, Figure 1 As shown), the specific distribution amount is shown in Table 1, and the distribution angle is shown in Table 2. Among them, the 4th gear focusing angle is 31.3°, the focusing time is 90 seconds, the material line is 1.4m, and the ore batch is 74t;

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066] When the edge airflow is overdeveloped, the edge will increase the ore distribution and reduce the coke distribution, while the center will increase the coke distribution, increasing the ore and coke loads at the edge and reducing the ore and coke loads at the center. When the center airflow is overdeveloped, the edge will reduce the ore distribution and increase the coke distribution, reducing the ore and coke loads at the edge.

[0067] When the temperature of the cold surface of the furnace cooling wall rises abnormally due to blowby, a hole is drilled between two cooling walls in the area with the highest heat flux intensity or the highest temperature to form a grouting hole and grouting is performed, wherein the heat flux intensity is the heat flow passing through a unit area in a unit time;

[0068] If the temperature in some parts of the furnace rises abnormally, block 1-2 air vents in the direction of the abnormally high temperature, and withdraw coal at a ratio of 10-15kg / t and remove the top pressure of 5-10kpa.

[0069] Example 2

[0070] This embodiment provides a 2500m 3 The method for maintaining a stable blast furnace hearth is mainly different from that of Example 1 in that the charging system is different, including: the charging system is O00023320000C00222222100, specifically as follows Figure 2 As shown, the 4th gear focusing angle is 31.3°, the focusing time is 90 seconds, the material line is 1.4m, and the ore batch is 74t;

[0071] When the edge airflow is overdeveloped, the edge will increase the ore distribution and reduce the coke distribution, while the center will increase the coke distribution, increasing the ore and coke loads at the edge and reducing the ore and coke loads at the center. When the center airflow is overdeveloped, the edge will reduce the ore distribution and increase the coke distribution, reducing the ore and coke loads at the edge.

[0072] When the temperature of the cold surface of the furnace cooling wall rises abnormally due to blowby, a hole is drilled between two cooling walls in the area with the highest heat flux intensity or the highest temperature to form a grouting hole and grouting is performed, wherein the heat flux intensity is the heat flow passing through a unit area in a unit time;

[0073] If the temperature in some parts of the furnace rises abnormally, block 1-2 air vents in the direction of the abnormally high temperature, and withdraw coal at a ratio of 10-15kg / t and remove the top pressure of 5-10kpa.

[0074] Comparative Example 1

[0075] The main difference between this comparative example and Example 1 is that the charging system is O00022222000C00032222200, as shown in the following figure: Figure 3 shown.

[0076] The water temperature difference of the blast furnace part, the wall temperature of the cooling wall and the heat flux intensity of the above-mentioned embodiments were measured, and the results are shown in Table 3.

[0077] Table 3

[0078]

[0079] The present invention firstly increases the amount of coke added in the center by reducing the number of ore distribution circles in the 4th gear or canceling the inner ring gear and appropriately extending the coke distribution time, so as to maintain the stability of the central coal gas flow and accelerate the replacement of the pulverized coke in the dead material column; secondly, adjusts the ore-coke ratio at the edge, and adjusts the 8th gear load at the edge (the ratio of the amount of ore distributed in the 8th gear / the amount of coke distributed in the 8th gear) to 4.8-5.2, loosens the edge to reduce the scouring of the cooling wall by the local airflow, and is suitable for the high cooling intensity of the copper cooling wall; finally, appropriately reduces the ore batch and reduces the ore-coke ratio of the middle ring belt, which is beneficial to the stability of the pressure difference in the furnace.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for maintaining stability of a blast furnace hearth, characterized in that: include: The throat of a blast furnace is divided into 11 equal parts with equal areas and coaxially arranged, and are numbered as 11 gears, 10 gears, 9 gears, 8 gears, 7 gears, 6 gears, 5 gears, 4 gears, 3 gears, 2 gears and 1 gear in sequence in the direction away from the wall of the blast furnace, and a distribution chute is used to distribute materials to each gear. The number of circles made by the distribution chute when distributing materials at each gear from the 11th gear to the 1st gear is: O00033320000C00222222000 or O00023320000C00222222100; Among them, C stands for coke and O stands for ore.

2. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: The blast furnace is 2500m 3 blast furnace.

3. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: The 4th gear focusing angle is 31-31.3°, focusing time is 89-91 seconds, material line is 1.3-1.4m, and ore batch is 73-74t.

4. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: The method satisfies at least one of the following af: a. The average particle size of the coke is 45-48 mm, and the particle size of the coke is 45-48 mm, accounting for > 55 wt%; b. The blast furnace coal ratio is 160-170kg / t; c. The blast furnace load is 4.9t / t or more; d. the blast furnace slag ratio is less than 335kg / t; e. The blast furnace charging grade is 57% or more; f. The blast furnace pressure difference is 155-160kPa.

5. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: When the edge airflow is overdeveloped, the ore distribution is increased and the coke distribution is reduced at the edge, while the coke distribution is increased in the center. The ore and coke loads at the edge positions are increased, while the ore and coke loads at the center positions are reduced.

6. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: When the central airflow is overdeveloped, the ore distribution at the edge is reduced and the coke distribution is increased, thereby reducing the ore and coke load at the edge positions.

7. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: Discharge flow rate Q = T / (β×P); where T is the total weight of the charge, β is the total number of revolutions of the charge chute at each gear, and P represents the time required for the charge chute to make one circle around the center of the blast furnace, in units of S.

8. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: The material distribution time of the material distribution chute at the specified gear is P×m±N seconds, where m is the number of revolutions when distributing a batch of coke or ore at the specified gear, and 0≤N≤5.

9. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: When the blowby causes the temperature of the cold surface of the furnace cooling wall to rise abnormally, holes are drilled between the two cooling walls in the area with the highest heat flux intensity or the highest temperature to form grouting holes and grouting is carried out, where the heat flux intensity is the heat flow rate passing through a unit area per unit time.

10. The method for maintaining stability of a blast furnace hearth according to claim 1, characterized in that: If the temperature in some parts of the furnace rises abnormally, block 1-2 air vents in the direction of the abnormally high temperature, and withdraw coal at a ratio of 10-15kg / t and remove the top pressure of 5-10kpa.

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