Method for stopping blast furnace and lowering material surface of blast furnace

Abstract

The present application belongs to the field of metallurgy, and particularly relates to a method for stopping blast furnace and lowering material surface, comprising the following contents: (1) adjusting the furnace operation before stopping; (2) adjusting the stopping material and optimizing the material distribution matrix; (3) pre-turbine, replacing the tuyere small sleeve and controlling the furnace top temperature; (4) stopping and lowering the material surface: 1. increasing the ratio of top pressure and hot blast pressure: the ratio of top pressure and hot blast pressure is increased to 0.68-0.75; 2. taking different degrees of control on the top temperature when the material surface is at different positions of the blast furnace: (1) when the material surface is above 1 / 2 of the bosh, the top temperature is controlled at 320-350 DEG C; (2) when the material surface is below 1 / 2 of the bosh, the top temperature is controlled at 280-300 DEG C; 3. spraying coal powder, oxygen enrichment, increasing and continuously maintaining the nitrogen gas injection of the tuyere after stopping the coal injection; 4. controlling the gas composition; 5. controlling the [Si] of the molten iron. The method can avoid the blast furnace explosion in the process of stopping and lowering the material surface, prolong the coal gas recovery time, shorten the time of stopping and lowering the material surface, save the coke consumption and reduce the cost.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a method for stopping a blast furnace empty charge line and lowering the charge level. Background Technology

[0002] When a blast furnace is in continuous production for a certain number of years, the refractory materials will be corroded to varying degrees. The composite bricks in the taphole area of ​​the hearth are severely corroded, and the mud packs cannot be repaired. It is necessary to shut down the furnace and reduce the amount of material to pour refractory materials into the taphole area for maintenance. Blast furnace shutdown and burden reduction typically employ two methods: material filling and empty charge line gas recovery. Material filling is safer, eliminating concerns about the collapse of residual brick lining during shutdown. However, cleaning the packing material after shutdown is time-consuming and labor-intensive, leading many companies to abandon it. Empty charge line gas recovery shutdown, on the other hand, is popular due to its significant reduction in furnace cleaning workload, shorter overhaul time, and partial gas recovery, which reduces air pollution and saves costs. However, conventional empty charge line shutdown and burden reduction methods usually involve reducing blast and top pressure (lowering the ratio of top pressure to hot blast pressure) and adjusting top water injection to control top temperature. Frequent detonation during shutdown and burden reduction can cause premature and significant blast reduction and gas cut-off. This results in prolonged shutdown and burden reduction times, safety instability, and the need for premature gas venting, increasing air pollution. Furthermore, shortened gas recovery time reduces recovery rates and increases company costs. Summary of the Invention

[0003] The purpose of this invention is to provide a method for shutting down and lowering the burden level in a blast furnace empty charge line, which solves the problems of frequent detonation and safety hazards that occur during the shutdown and burden level lowering process of traditional methods, as well as the problems of premature and significant reduction of blast furnace air and gas cut-off, resulting in long shutdown and burden level lowering time, shortened gas recovery time, increased air pollution, and increased enterprise costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for shutting down a blast furnace empty charge line and lowering the charge level includes the following:

[0006] (a) Adjusting the furnace operation before shutdown

[0007] One week before shutdown, stop using vanadium-titanium ore. Three days before shutdown, open all the tuyeres that were blocked during furnace protection, increase airflow to enrich oxygen and activate the hearth, ensuring smooth operation of the blast furnace. One day before shutdown, adjust the airflow according to the actual furnace condition to loosen the edge of the hearth, making it easier to clean after shutdown. Control the [Si] in the molten iron to 0.30-0.50%, maintain the physical heat of the molten iron ≥1500℃, and appropriately increase the [S] in the molten iron to 0.030-0.050%.

[0008] (ii) Adjusting the feed material for shutdown

[0009] On the day of shutdown, the blast furnace coal ratio is reduced from 170-180 kg / t to 155-165 kg / t, and the coke ratio is increased by 10-15 kg / t accordingly. In addition, the coke ratio is increased by 25-30 kg / t 3 hours before the planned material reduction and pre-shutdown. 50-100 kg of silica is added to each batch of ore for 5-7 batches. Before the material reduction, pulverized coal is injected normally, and 40 tons of coke are added to the surface. The fuel ratio is controlled to be 2-5 kg / t higher than the normal 510-515 kg / t. On the day before shutdown, the [Si] content in the molten iron is 0.50-0.70%, ensuring that the physical heat of the molten iron is ≥1500℃ and that the slag and iron have good fluidity.

[0010] (III) Pre-closure wind

[0011] After adding the coke to the furnace top, a pre-shutdown is carried out, and the tuyeres sleeves are replaced and maintained. Before the pre-shutdown, the top temperature is controlled at 250-280℃. After the pre-shutdown, the operation of the mechanical probe at 18.0-23.0 meters on the furnace top is checked.

[0012] (iv) Shutting down the furnace and lowering the feed level

[0013] 1. Increase the ratio of top pressure to hot air pressure

[0014] During normal blast furnace production, the ratio of top pressure to hot blast pressure is 0.55-0.57. During the shutdown process of lowering the burden level and reducing blast, the ratio of top pressure to hot blast pressure increases to 0.68-0.75.

[0015] 2. When the burden level is at different locations in the blast furnace, the blast furnace top temperature is controlled to varying degrees.

[0016] When lowering the material level, fully open the atomizing water guns on the normal furnace top, fix the maximum amount of atomizing water spraying on the furnace top, and control the top temperature between 280℃ and 350℃ by reducing air, reducing oxygen, and lowering air temperature. Keep the lower valve box and gear box cooled to the maximum extent, fully open the steam on the furnace top, and keep the nitrogen at sufficient pressure so that the temperature of the airtight box does not exceed 60℃.

[0017] 3. Inject pulverized coal, enrich oxygen, and increase and continuously maintain nitrogen injection at the tuyere.

[0018] After the blast furnace pre-shutdown blast and the burden level is lowered, oxygen enrichment and pulverized coal injection are started into the blast. The pulverized coal injection rate is maintained at 24-25 t / h, and the total oxygen enrichment is increased from the initial 1500-2000 m³ / h. 3 / h increased to 3000-4000m 3 / h, and then gradually increase to 9500-9900m 3 / h (each oxygenation increment is 1500-2000m) 3 / h, with an interval of 10-15 minutes); stop pulverized coal injection when the material surface is almost inside the furnace waist, and stop for 3000-3500m. 3 / h of oxygen supply after the machine, with oxygen enrichment before the machine ranging from 6000-6500m³ / h. 3 / h reduced to 3000-4000m 3 Increase and maintain nitrogen injection at the vents at a rate of 700-800 m³ / h. 3 / h increased to 1500-2000m 3 / h, effectively diluting the O2 and H2 content in the coal gas; the oxygen enrichment at the machine entrance is 3000-4000m³ / h. 3 / h reduced to 1500-2000m 3 / h, oxygen enrichment before shutdown when the material level is about to enter the furnace belly;

[0019] 4. Control the composition of coal gas

[0020] (1) The O2 content in the gas shall be controlled within 2.0%;

[0021] (2) The CO2 content in the gas shall be controlled within 15.0%;

[0022] 5. Controlling the tapping of molten iron [Si]

[0023] Sufficient heat in the hearth is crucial for shutting down and lowering the charge level. During the shutdown and charge level lowering process, the Si content of the molten iron should be controlled between 0.50% and 0.70%, and the physical heat of the molten iron should be above 1490℃. This ensures sufficient heat in the hearth, which is beneficial for improving the fluidity of the slag and iron in the hearth and allowing it to be discharged in a timely manner.

[0024] Preferably, step (ii) of adjusting the shutdown charge also includes optimizing the charge distribution matrix, the specific details of which are as follows:

[0025] (1) The planned material lowering line shall be implemented according to the principle of reducing the angle by 1.0° for every 0.5 meters the material lowering line is;

[0026] (2) The blast furnace feed line is lowered to 3.0 meters (normal production feed line is 1.50 meters), and the coke and ore platforms are simultaneously reduced by 3.0°.

[0027] (3) When using 40 tons of coke, the maximum angle of the coke cloth is reduced from the normal 40.5° to 36.5°, the minimum angle of the cloth is reduced from the normal 29.5° to 25.5°, and the difference between the maximum and minimum angles of the coke is adjusted from the normal 11.0° to 10.0°. Maintain 6 gears, cloth 14 times, and guide the airflow at the edge.

[0028] Preferably, step (iv) 2, controlling the top temperature of the material surface at different parts of the blast furnace, further includes the following:

[0029] (1) When the material level is above 1 / 2 of the furnace belly, the blast furnace top temperature is controlled at 320-350℃;

[0030] (2) When the material level is at or below 1 / 2 of the furnace belly (including the part below 1 / 2 of the furnace belly and then into the furnace waist), the top temperature of the blast furnace is controlled at 280-300℃ to effectively avoid blast furnace detonation and ensure the safety of shutting down the furnace and lowering the material level.

[0031] Preferably, step 3 in (iv) further includes controlling the temperature of the airtight chamber at 20.0-24.0℃.

[0032] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0033] (1) Adjust the airflow to loosen the edge of the furnace hearth one day before shutdown, based on the actual furnace condition, so that the furnace hearth is easy to clean after shutdown;

[0034] (2) No additional furnace top water spraying device is required. Open all atomizing water spraying guns on the furnace top, fix the atomizing water spraying volume, reduce the air in advance, control the top temperature of the material surface at different parts of the blast furnace, prevent blast furnace explosion, and ensure the safety of shutting down the furnace and lowering the material surface.

[0035] (3) Optimize the material distribution matrix, stabilize the central airflow, enhance the stability of the furnace condition, help reduce the hearth circulation, slow down the erosion of the hearth taphole refractory, and improve the safety of the hearth.

[0036] (4) In the traditional process of shutting down the furnace and reducing the amount of material, the ratio of top pressure to hot air pressure is reduced to 0.40-0.45. This method can reduce the gas flow rate by reasonably increasing the ratio of top pressure to hot air pressure, and effectively improve the process of shutting down the furnace and reducing the amount of material.

[0037] (5) By continuously injecting nitrogen, the content of O2 and H2 in the coal gas is effectively diluted and reduced, the coal gas recovery time is delayed, and the safety of the furnace shutdown and material level is ensured.

[0038] (6) The upper limit of CO2 content in the gas returned to the process is controlled within 15.0%, which both extends the gas recovery time and ensures the safety of the gas recovery process;

[0039] (7) This method uses a combination of processes, including early shutdown of vanadium-titanium furnace protection, adjustment of shutdown charge, optimization of charge distribution matrix, blast furnace blast reduction during shutdown to increase the top pressure to hot blast pressure ratio, fixed atomization water volume, early and reasonable blast reduction to control the top temperature of the charge surface at different parts of the blast furnace, blast furnace coal shutdown to maintain maximum nitrogen injection from the tuyeres, and control of the upper limit of CO2 content in the gas returning to the process gas. This method minimizes the occurrence of detonation during shutdown and charge reduction, extends gas recovery time, shortens blast furnace shutdown and charge reduction time, saves coke consumption, reduces costs, and achieves the goal of safe, efficient, and economical shutdown and charge reduction. Detailed Implementation

[0040] The technical solution of the present invention will be described in detail below with reference to the embodiments.

[0041] 5 #Furnace volume 1080m³ 3 The furnace adopted a bell-less top charging system with charging cars and north and south tapping areas. Since the major overhaul began at 18:00 on January 11, 2018, the refractory materials have experienced varying degrees of erosion. The combined brickwork in the hearth taphole area is severely eroded, making mud-filled brickwork difficult to maintain. The erosion is even more severe at the south taphole, with the second section on both sides of the taphole showing signs of damage. # 33 # The heat flux intensity of the cooling wall continued to rise, reaching 12500 KCal / (m²) on August 19, 2024. 2 The heat flux intensity reached 13100 KCal / (m³) on September 5th. 2 The heat flux intensity reached 14700 KCal / (m³) on September 7th. 2 On September 18th, furnace conditions fluctuated and wind was reduced, with heat flow intensity gradually decreasing to 13700 KCal / (m³). 2 As the furnace conditions were restored and adjusted, the smelting strength increased, and the heat flux intensity gradually increased, reaching 15100 KCal / (m²) on November 2nd. 2 The heat flux intensity reached 15400 KCal / (m³) on November 18th. 2 The heat flux intensity reached 15400 KCal / (m³) on November 18th. 2 The heat flux intensity reached a peak of 16700 KCal / (m³) on December 25th. 2 (h), the water temperature difference on both sides of the taphole reached a maximum of 1.04℃, and the furnace shell temperature reached a maximum of 80℃, resulting in a safety production accident in the south taphole area where the hearth and furnace shell burned through, and the blast furnace urgently entered the furnace protection state.

[0042] Dimensions of various parts of the blast furnace

[0043]

[0044] The method for shutting down a blast furnace and lowering the burden level, as described in this invention, involves releasing residual iron and performing localized casting treatment at the hearth taphole. The specific details of the method for shutting down a blast furnace and lowering the burden level are as follows:

[0045] (a) Adjusting the furnace operation before shutdown

[0046] 1. Open wind tunnel #1 at 11:15 AM on December 30, 2024;

[0047] 2. The vanadium-titanium mine will cease operations at 1:00 AM on December 31st;

[0048] 3. At 12:14 on January 2, 2025, vent #20 was opened and fully opened.

[0049] (ii) Adjusting the shutdown charge and optimizing the charge distribution matrix

[0050] 1. Adjust the coke ratio and coal ratio of the furnace feed for shutdown.

[0051] On January 6th, a pre-shutdown of the furnace is scheduled to begin at 12:30. Starting at 9:30, the coke ratio of the furnace charge will be increased from 350 kg / t to 378 kg / t; the coal ratio will be decreased from 165 kg / t to 135-140 kg / t. Specific adjustments are as follows:

[0052]

[0053] 2. Optimize the fabric matrix

[0054] The specific details of the standard material placement matrix are as follows: For coke, the maximum angle is 40.5°, the minimum angle is 29.5°, divided into 6 levels, with a total of 14 rounds of placement. The platform width is 11.0°, and the average angle is 35.93°. The maximum angle for coke placement is 40.5° (3 rounds), 38.5° (3 rounds), 36.5° (2 rounds), 34.5° (2 rounds), and 32.5° (2 rounds), with a minimum angle of 29.5° (2 rounds). For ore, the maximum angle is 41.0°, the minimum angle is 33.5°, divided into 5 levels, with 12 rounds of placement. The platform width is 7.5°, and the average angle for ore is 37.8°. 8°, ore-coke angle difference 1.95°, maximum ore angle 41.0° 3 rings of charging, ore angle 39.5° 3 rings of charging, ore angle 37.5° 2 rings of charging, ore angle 35.5° 2 rings of charging, ore angle 33.5° 2 rings of charging, central coke ratio 14.3%, reducing the proportion of coke in the central non-ore zone, improving the permeability of the ring zone, forming a platform + funnel charging pattern, stabilizing the central airflow, enhancing furnace stability, and helping to reduce the impact of hearth circulation, the impact of charging tip collision with the furnace wall rebound, and the need to scour the furnace wall adhesion during the charging surface reduction process. The blast furnace coke and ore charging angles are reduced simultaneously, and the edges are appropriately cleared. The adjustments are as follows:

[0055] (1) At 10:00, the blast furnace will begin to lower the material line in a planned manner. The coke and ore platforms will be lowered by 1.0° for every 0.5 meters the material line is lowered.

[0056] (2) At 11:20, the blast furnace charge line was lowered to 3.0 meters (1.50 meters during normal production), and the coke and ore platforms were simultaneously reduced by 3.0°.

[0057] (3) When 40 tons of coke are put on the surface at 11:30, the maximum angle of the coke cloth is reduced from the normal 40.5° to 36.5°, the minimum angle of the cloth is reduced from the normal 29.5° to 25.5°, and the difference between the maximum and minimum angles of the coke is adjusted from the normal 11.0° to 10.0°. Maintain 6 gears, cloth 14 times, and guide the airflow at the edge.

[0058] (III) Pre-closure

[0059] 12:18-13:28 Pre-shutdown of ventilation, replacement of the well-maintained small sleeves of tuyeres #13 and #18; inspection of the operation of the mechanical probe at 19.0 meters on the furnace top.

[0060] (iv) Shutting down the furnace and lowering the feed level

[0061] 1. Inject pulverized coal, enrich oxygen, and continuously maintain nitrogen injection at the tuyeres.

[0062]

[0063] After the blast furnace blast furnace blows air at 13:28 and the burden level is lowered, the pulverized coal injection rate is maintained at 24-25 t / h, and the total oxygen enrichment is increased from 1500-2000 m³ / h. 3 / h increased to 3000-4000m 3 / h, and then gradually increase to 9500-9900m 3 / h (each oxygenation increment is 1500-2000m) 3 / h, intervals of 10-15 minutes); at 16:45 the top temperature was 350℃, higher than the normal 180-220℃, after shutdown, oxygen enrichment was carried out; at 17:00 the material level at 14.35 meters of the feed line was at the lower part of the furnace body, almost entering the furnace waist, pulverized coal injection was stopped, and nitrogen injection was reduced from 700-800 m³ / h. 3 / h increased to 1500-2000m 3 / h, effectively diluting the O2 and H2 content in the coal gas; at 17:20, the top temperature was 350℃, higher than the normal 180-220℃, and the oxygen enrichment in front of the machine was 3200-3400m. 3 / h reduced to 1800-1820m 3 / h; 17:35 The material level at 15.33 meters of the feed line enters the furnace belly, and oxygen is enriched before shutdown;

[0064] 2. Control parameters

[0065]

[0066] During the furnace shutdown and charge reduction process, no additional furnace top water spraying device was installed. All six existing atomizing water sprayers on the furnace top were fully operational, with the maximum water spray volume controlled at 59.0 m³. 3 / h, and then control the top temperature by reducing oxygen, reducing wind and reducing wind temperature: (1) When the material line is 18.50 meters, that is, when the material surface is above 1 / 2 of the furnace belly, the top temperature of the blast furnace is controlled at 320-350℃; (2) When the material line is below 18.50 meters, that is, when the material surface enters below 1 / 2 of the furnace belly, the top temperature of the blast furnace is controlled at 280-300℃, effectively controlling the occurrence of detonation during the process of shutting down the blast furnace and lowering the material surface, and ensuring the safety of shutting down the blast furnace and lowering the material surface;

[0067] During the shutdown and lowering of the blast furnace charge level (before cutting off the gas supply), maintain a reasonably high top pressure. The ratio of blast furnace top pressure to hot blast pressure should be kept at 0.68-0.75, which is higher than the normal production ratio of 0.55-0.57. This helps to reduce the gas flow rate and shorten the shutdown and lowering time. The temperature of the airtight box should be controlled at 20.0-24.0℃ to ensure the safe operation of the furnace top equipment.

[0068] 3. Gas composition control

[0069]

[0070] During this shutdown and feed level reduction process, the O2 recovery from the coal gas was controlled at 0.20-1.50%, meeting the control requirements. (23:0417) # -20 # The vent was emptied, and the CO2 content in the gas was 14.80%, close to the upper limit of 15.0%. Given that materials were continuously entering the vent, to ensure safety, the gas supply was cut off at 23:13. 23:22 # -6 # The tuyeres were emptied; the shutdown and reduction of the material level at 0:00 on January 7th was completed without any explosions.

[0071] 4. Controlling the tapping of molten iron from the blast furnace [Si]

[0072]

[0073] During this shutdown process, a total of 4 taps were made, with the Si content of the molten iron being 0.51%, 0.68%, 0.61%, and 1.02% respectively. The Si content of the molten iron was between 0.50% and 0.70%, and the physical heat of the molten iron was between 1490 and 1500℃, which was sufficient to meet the requirements for controlling the material level during shutdown.

[0074] In this embodiment, pulverized coal injection was maintained at a moderate level during the blast furnace shutdown and burden reduction process, and then stopped when the burden level was almost inside the furnace waist, thus saving coke. Coal gas was recovered and directly lowered to the tuyeres area, reducing air pollution from vented coal gas. The coal gas recovery time was 9 hours and 45 minutes, accounting for 92.56% of the shutdown and burden reduction time. Simultaneously, coal gas recovery generated economic benefits; a total of 1,472,406 m³ of coal gas was recovered in this instance. 3 The furnace shutdown and charge reduction began at 13:28 on January 6th and ended at 0:00 on January 7th, lasting 10 hours and 32 minutes. This shortened the shutdown and charge reduction time without any detonation, achieving the goals of a safe, efficient, and economical shutdown and charge reduction. The economic benefits are as follows:

[0075] (1) The amount of recovered coal gas accounts for 97.62% of the total coal gas volume, and its benefit is RMB147,200;

[0076] (2) During the shutdown process, the coal injection was maintained at 13:28 and the air was supplied. The coal was stopped at 17:00, with a total coal injection volume of 93 tons, saving 68,260 yuan in coke benefits. The goal of safe and efficient shutdown and material level reduction was achieved.

Claims

1. A method for stopping a blast furnace empty charge line and lowering the charge level, characterized in that, Includes the following: (a) Adjusting the furnace operation before shutdown One week before shutdown, stop using vanadium-titanium ore. Three days before shutdown, open all the tuyeres that were blocked during furnace protection, increase airflow to enrich oxygen and activate the hearth, ensuring smooth operation of the blast furnace. One day before shutdown, adjust the airflow according to the actual furnace condition to loosen the edge of the hearth, making it easier to clean after shutdown. Control the [Si] in the molten iron to 0.30-0.50%, maintain the physical heat of the molten iron ≥1500℃, and increase the [S] in the molten iron to 0.030-0.050%. (ii) Adjusting the feed material for shutdown On the day of shutdown, the blast furnace coal ratio is reduced from 170-180 kg / t to 155-165 kg / t, and the coke ratio is increased by 10-15 kg / t accordingly. In addition, the coke ratio is increased by 25-30 kg / t 3 hours before the planned material reduction and pre-shutdown. 50-100 kg of silica is added for 5-7 batches of material. Before the material reduction, normal coal injection is carried out, and 40 tons of coke are added to the cover surface. The fuel ratio is controlled to be 2-5 kg / t higher than the normal 510-515 kg / t. On the day before shutdown, the [Si] content in the molten iron is 0.50-0.70%, ensuring that the physical heat of the molten iron is ≥1500℃ and that the slag and iron have good fluidity. (III) Pre-closure After adding the coke to the furnace top, a pre-shutdown is carried out, and the tuyeres sleeves are replaced and maintained. Before the pre-shutdown, the top temperature is controlled at 250-280℃. After the pre-shutdown, the operation of the mechanical probe at 18.0-23.0 meters on the furnace top is checked. (iv) Shutting down the furnace and lowering the feed level (1) Increase the ratio of top pressure to hot air pressure During normal blast furnace production, the ratio of top pressure to hot blast pressure is 0.55-0.

57. During the shutdown process of lowering the burden level and reducing blast, the ratio of top pressure to hot blast pressure increases to 0.68-0.

75. (2) When the burden surface is in different parts of the blast furnace, the top temperature of the blast furnace is controlled to different degrees. When lowering the material level, fully open the atomizing water guns on the normal furnace top, fix the maximum amount of atomizing water spraying on the furnace top, and control the top temperature between 280℃ and 350℃ by reducing air, reducing oxygen, and lowering air temperature. Keep the lower valve box and gear box cooled to the maximum extent, fully open the steam on the furnace top, and keep the nitrogen at sufficient pressure so that the temperature of the airtight box does not exceed 60℃. (3) Inject pulverized coal, enrich oxygen, and increase and maintain nitrogen injection at the tuyere. After the blast furnace pre-shutdown blast and the burden level is lowered, oxygen enrichment and pulverized coal injection are started into the blast, with the pulverized coal injection rate maintained at 24-25 t / h and the total oxygen enrichment from 3000-4000 m³ / h. 3 / h gradually increased to 9500-9900m 3 / h; Stop pulverized coal injection when the material level is almost inside the furnace waist, stop for 3000-3500m 3 / h of oxygen supply after the machine, with oxygen enrichment before the machine ranging from 6000-6500m³ / h. 3 / h reduced to 3000-4000m 3 Increase and maintain nitrogen injection at the vents at a rate of 700-800 m³ / h. 3 / h increased to 1500-2000m 3 / h, effectively diluting the O2 and H2 content in the coal gas; the oxygen enrichment at the machine entrance is 3000-4000m³ / h. 3 / h reduced to 1500-2000m 3 / h, oxygen enrichment before shutdown when the material level is about to enter the furnace belly; (4) Controlling the composition of coal gas ① The O2 content in the gas should be controlled below 2.0%; ② The CO2 content in the gas should be controlled within 15.0%; (5) Controlling the tapping of molten iron [Si] Sufficient heat in the hearth is crucial for shutting down the furnace and lowering the charge level. During the shutdown and charge level lowering process, the Si content of the molten iron should be controlled between 0.50% and 0.70%, and the physical heat of the molten iron should be above 1490℃.

2. The method for stopping and lowering the burden level in a blast furnace empty charge line according to claim 1, characterized in that, The second part, adjusting the shutdown charge, also includes optimizing the charge distribution matrix, the details of which are as follows: ① For planned material lowering, the coke and ore platforms shall be lowered by 1.0° for every 0.5 meters the material level is lowered; ② The blast furnace charge line is lowered to 3.0 meters, and the coke and ore platforms are simultaneously reduced by 3.0 degrees. ③ When using 40 tons of top-coke, the maximum angle of the coke cloth is reduced from the normal 40.5° to 36.5°, the minimum angle of the cloth is reduced from the normal 29.5° to 25.5°, and the difference between the maximum and minimum angles of the coke is adjusted from the normal 11.0° to 10.0°, maintaining 6 gears and 14 cloth rotations.

3. The method for stopping and lowering the burden level in a blast furnace empty charge line according to claim 1, characterized in that, The control of the top temperature of the material surface at different parts of the blast furnace in section (iv) (2) also includes the following: ① When the material level is above 1 / 2 of the furnace belly, the blast furnace top temperature should be controlled at 320-350℃; ② When the material level is at or below 1 / 2 of the furnace belly, the blast furnace top temperature should be controlled at 280-300℃.

4. The method for stopping and lowering the burden level in a blast furnace empty charge line according to claim 1, characterized in that, (3) in (iv) also includes controlling the temperature of the airtight box at 20.0-24.0℃.

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