Blast furnace empty stockline blowing-out charge level lowering method

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to a blast furnace empty stockline blow-out charge level lowering method which comprises the following steps: (1) adjusting in-furnace operation before blow-out; (2) adjusting a furnace stopping material, and optimizing a material distribution matrix; (3) pre-damping down, replacing a tuyere small sleeve, and controlling the furnace top temperature; and (4) blowing out the furnace and lowering the charge level: 1, increasing the ratio of top pressure to hot air pressure to 0.68-0.75; 2, when the charge level is at different parts of the blast furnace, the top temperature is controlled to different degrees: (1) when the charge level is above 1 / 2 position of the bosh, the top temperature is controlled to be 320-350 DEG C; (2) when the charge level is below the 1 / 2 position of the bosh, the top temperature is controlled to be 280-300 DEG C; 3, injecting pulverized coal, enriching oxygen, stopping coal injection, and then increasing and continuously keeping nitrogen injection at the tuyere; 4, controlling gas components; and 5, controlling the tapping molten iron [Si]. According to the method, knocking in the blowing-out charge level lowering process of the blast furnace is avoided to the maximum extent, the gas recovery time is prolonged, the blowing-out charge level lowering time of the blast furnace is shortened, the coke consumption is reduced, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgy, and particularly relates to a method for stopping blast furnace and lowering material surface. BACKGROUND

[0002] The refractory materials of a blast furnace are eroded to different degrees during continuous production for a certain period of time, among which the combined bricks in the iron notch area of the furnace hearth are severely eroded, the mud bag cannot be repaired, and the refractory materials in the iron notch area need to be poured and maintained after the blast furnace is stopped and the material surface is lowered. The blast furnace is usually stopped by using the material filling method and the airless line gas recovery method. The material filling method is safer and does not worry about the collapse of the remaining brick lining of the blast furnace shaft during the stopping process, but cleaning the filling material in the furnace after stopping is time-consuming and laborious, so many enterprises have stopped using it. The airless line gas recovery method is welcomed by enterprises because it greatly reduces the cleaning workload, shortens the repair time, recovers part of the gas, reduces air pollution, saves costs, but the conventional airless line stopping method usually adopts the operation of reducing the wind and the low top pressure (reducing the ratio of top pressure to hot wind pressure) and increasing the water control top temperature on the furnace top, and the blast furnace is prone to frequent explosions during the process of stopping and lowering the material surface, which leads to a large reduction in the wind and the cutting of gas in advance, a long time for the blast furnace to be stopped and the material surface to be lowered, safety instability, the blast furnace needs to be cut off in advance to release the gas, which increases air pollution, shortens the recovery time of the gas, reduces the recovery rate, and increases the cost of enterprises. SUMMARY

[0003] The purpose of the present application is to provide a method for stopping and lowering the material surface of a blast furnace with an airless line, which solves the problems of the traditional method that the blast furnace is prone to frequent explosions during the process of stopping and lowering the material surface, which leads to a large reduction in the wind and the cutting of gas in advance, a long time for the blast furnace to be stopped and the material surface to be lowered, a reduction in the recovery time of the gas, an increase in air pollution, and an increase in the cost of enterprises.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A method for stopping and lowering the material surface of a blast furnace with an airless line, comprising the following contents: (1) Adjusting the in-furnace operation before stopping One week before stopping, stop using vanadium-titanium ore, open all the tuyeres blocked during furnace protection three days before stopping, increase the oxygen content by increasing the air flow to activate the furnace hearth, ensure the smooth operation of the blast furnace, adjust the air flow to loosen the edge of the furnace hearth the day before stopping according to the actual furnace condition, make the furnace hearth easy to clean after stopping, control the [Si] in molten iron to be 0.30-0.50%, keep the physical heat of molten iron ≥ 1500℃, and appropriately increase the [S] in molten iron to 0.030-0.050%; (2) Adjusting the stopping material The coal ratio of the blast furnace on the day of shutdown was reduced from 170-180 Kg / t to 155-165 Kg / t, the coke ratio was increased by 10-15 Kg / t accordingly, and the coke ratio was increased by 25-30 Kg / t 3 hours before the planned reduction of the material surface, 50-100 Kg of silica was added in each batch of ore for 5-7 batches of material, the normal coal injection was performed before the reduction of the material surface, 40 t of capping coke was used, the fuel ratio was controlled to be 2-5 Kg / t higher than the normal 510-515 kg / t, the [Si] in the molten iron on the day before the shutdown was 0.50-0.70%, the physical heat of the molten iron was ensured to be greater than or equal to 1500℃, and the slag-iron fluidity was good; (Three) Pre-shutdown After the capping coke was added, pre-shutdown was performed, and the wind port small sleeve was replaced and maintained. The top temperature was controlled to be 250-280℃ before the pre-shutdown, and the operation of the 18.0-23.0 meter mechanical probe was checked after the pre-shutdown. (Four) Shutdown and reduction of the material surface 1. Increase the ratio of the top pressure to the hot blast pressure During the normal production of the blast furnace, the ratio of the top pressure to the hot blast pressure was 0.55-0.57, and during the reduction of the material surface, the ratio of the top pressure to the hot blast pressure was increased to 0.68-0.75. 2. Control the top temperature of the blast furnace at different degrees when the material surface is at different positions of the blast furnace When the material surface is reduced, the normal blast furnace top atomizing water gun is fully opened, the maximum amount of fixed blast furnace top atomizing water is used, the top temperature is controlled to be between 280℃ and 350℃ by reducing the air, reducing the oxygen, and reducing the air temperature, the lower valve box and the gear box are maximally cooled, the blast furnace top steam is fully opened, and the nitrogen gas maintains sufficient pressure to ensure that the air-tight box temperature does not exceed 60℃. 3. Spray coal powder, rich oxygen, and increase and continuously maintain the nitrogen gas injection at the wind port After the blast furnace pre-shutdown and the reduction of the material surface, the rich oxygen is added to the blast and the coal powder is injected at the wind port, the amount of coal powder injection is maintained at 24-25 t / h, the total amount of rich oxygen is increased from 1500-2000 m 3 / h in the initial stage to 3000-4000 m 3 / h, and then gradually increased to 9500-9900 m 3 / h (the oxygen increase is 1500-2000 m 3 / h each time, and the interval time is 10-15 minutes); the coal injection is stopped when the material surface enters the furnace waist, the oxygen is stopped after 3000-3500 m 3 / h, the amount of oxygen before the machine is reduced from 6000-6500 m 3 / h to 3000-4000 m 3 / h, the nitrogen gas injection at the wind port is increased and continuously maintained, and the amount of nitrogen gas is increased from 700-800 m 3 / h to 1500-2000 m 3 / h, the oxygen-rich amount before the machine is stopped is from 3000-4000m 3 / h is reduced to 1500-2000m 3 / h, the oxygen-rich amount before the machine is stopped is from 3000-4000m 4. Controlling the gas composition (1) the O2 in the gas is controlled within 2.0%; (2) the CO2 in the gas is controlled within 15.0%; 5. Controlling the [Si] in the tapping molten iron The heat of the hearth is sufficient, which is important for stopping the blast furnace and lowering the material surface. During the process of stopping the blast furnace and lowering the material surface, the [Si] in the molten iron is controlled between 0.50-0.70%, and the physical heat of the molten iron is above 1490℃, so as to ensure that the heat of the hearth is sufficient, which is beneficial to improving the flowability of the hearth slag and iron, and making them be discharged and drained in time.

[0005] Preferably, the (two) adjusting the stopping material also includes optimizing the material distribution matrix, and the specific content is as follows: (1) plannedly lowering the material line, the coke and ore platform is executed according to the principle that the coke and ore platform is reduced by 1.0° when the material line is lowered by 0.5m; (2) when the material line of the blast furnace is lowered to 3.0m (the normal production material line is 1.50m), the coke and ore platform is simultaneously reduced by 3.0°; (3) when the 40 tons of cover coke is distributed, the maximum angle of the coke distribution is reduced from the normal 40.5° to 36.5°, the minimum angle of the coke distribution is reduced from the normal 29.5° to 25.5°, the difference between the maximum angle and the minimum angle of the coke is adjusted from the normal 11.0° to 10.0°, 6 gears are kept, 14 circles of distribution are kept, and the edge airflow is dredged.

[0006] Preferably, the (four) 2 controlling the top temperature of the material surface at different positions of the blast furnace further includes the following content: (1) when the material surface is above the position of 1 / 2 of the bosh, the top temperature of the blast furnace is controlled to be 320-350℃; (2) when the material surface is at the position of 1 / 2 of the bosh and below (including the position below 1 / 2 of the bosh, and then entering the bosh), the top temperature of the blast furnace is controlled to be 280-300℃, so as to effectively avoid the occurrence of the blast furnace shock, and ensure the safety of stopping the blast furnace and lowering the material surface.

[0007] Preferably, the (four) 3 further includes that the temperature of the gas-tight box is controlled to be 20.0-24.0℃.

[0008] Compared with the prior art, the present application has the following beneficial effects: (1) the edge airflow of the blast furnace is adjusted according to the actual furnace condition one day before stopping the blast furnace, so that the blast furnace hearth is good for cleaning after stopping the blast furnace; (2) Without additional installation of the furnace top water device, opening all the atomized water guns on the furnace top, fixing the atomized water volume, reasonably reducing the air volume in advance, controlling the top temperature of the material surface at different parts of the blast furnace, preventing the blast furnace from exploding, and ensuring the safety of the blast furnace material surface reduction; (3) Optimizing the distribution matrix, stabilizing the central gas flow, enhancing the stability of the furnace condition, reducing the furnace ring flow, slowing down the erosion of the furnace cylinder iron mouth refractory, and improving the safety of the furnace cylinder; (4) The ratio of top pressure to hot blast pressure in the traditional blast furnace shutdown and material surface reduction process is reduced to 0.40-0.45, and the ratio of top pressure to hot blast pressure is reasonably increased by this method, which is beneficial to reduce the gas flow rate and effectively improve the blast furnace shutdown and material surface reduction process; (5) By continuously injecting nitrogen, the O2 and H2 contents in the gas are effectively diluted and reduced, the gas recovery time is delayed, and the safety of the blast furnace shutdown and material surface reduction is ensured; (6) The upper limit value of CO2 content in the gas during the gas return process is controlled within 15.0%, which not only prolongs the gas recovery time but also ensures the safety of the gas recovery process; (7) The method uses early vanadium-titanium furnace protection, adjusts the blast furnace shutdown material, optimizes the distribution matrix, increases the ratio of top pressure to hot blast pressure during the blast furnace shutdown process, fixes the atomized water volume, reasonably reduces the air volume in advance to control the top temperature of the material surface at different parts of the blast furnace, keeps the maximum amount of nitrogen injection from the tuyere coal gun during the blast furnace coal shutdown, controls the upper limit value of CO2 content in the gas during the gas return process, and uses a variety of process combinations to maximize the avoidance of blast furnace explosion during the blast furnace shutdown and material surface reduction process, delay the gas recovery time, shorten the blast furnace shutdown and material surface reduction time, save the amount of coke, reduce the cost, and achieve the purpose of safe, efficient and economic blast furnace shutdown and material surface reduction. DETAILED DESCRIPTION

[0009] The technical solutions of the present application will be described in detail below in conjunction with the embodiments.

[0010] 5 # The blast furnace capacity is 1080m 3 , adopts a bell-less top, a material car charging, and a north-south casthouse, and the refractory has been eroded to varying degrees since the 18:00 repair production on January 11, 2018, among which the combined brick in the furnace cylinder iron mouth area is severely eroded, the mud bag is difficult to maintain, and the south iron mouth is more severely eroded, the second segment of the iron mouth on both sides is severely eroded, and the refractory is difficult to maintain. # , 33 # The cooling wall heat flow intensity continues to rise, and on August 19, 2024, the heat flow intensity reaches 12500 KCal / (m 2 .h), on September 5, the heat flow intensity reaches 13100 KCal / (m 2 .h), on September 7, the heat flow intensity reaches 14700 KCal / (m 2 .h), on September 18, the furnace condition fluctuates and the air volume is adjusted, and the heat flow intensity gradually decreases to 13700 KCal / (m 2As 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.

[0011] Dimensions of various parts of the blast furnace

[0012] 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: (a) Adjusting the furnace operation before shutdown 1. Open wind tunnel #1 at 11:15 AM on December 30, 2024; 2. The vanadium-titanium mine will cease operations at 1:00 AM on December 31st; 3. At 12:14 on January 2, 2025, vent #20 was opened and fully opened.

[0013] (ii) Adjusting the shutdown charge and optimizing the charge distribution matrix 1. Adjust the coke ratio and coal ratio of the furnace feed for shutdown. 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:

[0014] 2. Optimize the fabric matrix The specific conditions of the conventional burden distribution matrix are as follows: the maximum angle of coke distribution is 40.5°, the minimum angle is 29.5°, there are 6 gears, a total of 14 circles of distribution, the platform width is 11.0°, the average angle is 35.93°, 3 circles of distribution at the maximum angle of coke distribution of 40.5°, 3 circles of distribution at the coke angle of 38.5°, 2 circles of distribution at the coke angle of 36.5°, 2 circles of distribution at the coke angle of 34.5°, 2 circles of distribution at the coke angle of 32.5°, and 2 circles of distribution at the minimum angle of 29.5°; the maximum angle of ore distribution is 41.0°, the minimum angle is 33.5°, there are 5 gears, a total of 12 circles of distribution, the platform width is 7.5°, the average angle of ore is 37.88°, the difference between the ore and coke angles is 1.95°, 3 circles of distribution at the maximum angle of ore of 41.0°, 3 circles of distribution at the ore angle of 39.5°, 2 circles of distribution at the ore angle of 37.5°, 2 circles of distribution at the ore angle of 35.5°, 2 circles of distribution at the ore angle of 33.5°, the proportion of center coke is 14.3%, the proportion of coke in the center non-ore area is reduced, the gas permeability of the ring belt is improved, the distribution mode of platform + funnel is formed, the center gas flow is stabilized, the furnace condition stability is enhanced, the furnace condition stability is improved, the reduction of the furnace ring flow is beneficial, the impact of the distribution pile tip on the furnace wall is reduced, the process of reducing the material surface needs to be flushed, the coke and ore distribution angles are the same, the edge is moderately dredged, and the adjustment conditions are as follows: (1) At 10:00, the blast furnace starts to reduce the planned material line, and the coke and ore platforms are reduced by 0.5 meters according to the principle of reducing 1.0° for each 0.5 meters of the material line; (2) At 11:20, the material line of the blast furnace is reduced to 3.0 meters (the normal production material line is 1.50 meters), and the coke and ore platforms are simultaneously reduced by 3.0°; (3) At 11:30, when the 40 tons of cover coke is started, the maximum angle of coke distribution is reduced from the normal 40.5° to 36.5°, the minimum angle of coke distribution is reduced from the normal 29.5° to 25.5°, the difference between the maximum and minimum angles of coke is adjusted from the normal 11.0° to 10.0°, there are still 6 gears, the distribution is 14 circles, and the edge gas flow is dredged.

[0015] (Three) Pre-wind From 12:18 to 13:28, the pre-wind is performed, the 13# and 18# tuyere small sleeves are replaced, and the operation of the 19.0 meter mechanical probe of the furnace top is checked.

[0016] (Four) Stopping the blast furnace and reducing the material surface 1. Spray coal powder, rich oxygen, and continuously maintain nitrogen injection at the tuyere

[0017] After the blast furnace is sent at 13:28 and the material surface is reduced, the amount of coal powder injection is maintained at 24-25 t / h, the total amount of rich oxygen is increased from 1500-2000 m 3 / h to 3000-4000 m 3 / h, and then gradually increased to 9500-9900 m3 / 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; 2. Control parameters

[0018] 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; 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. 3. Gas composition control

[0019] 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 material level reduction were completed at 0:00 on January 7th, and no explosions occurred during the entire process. 4. Control of blast furnace tapping molten iron [Si]

[0020] In this shutdown process, a total of 4 times, the tapping of molten iron [Si] were 0.51%, 0.68%, 0.61%, 1.02%, molten iron [Si], between 0.50-0.70%, molten iron physical heat in 1490-1500 ℃, sufficient heat, to meet the requirements of the shutdown and the control of the material surface.

[0021] This embodiment in the process of blast furnace shutdown and material surface, then stop spraying coal when the material surface into the waist, save the coke; coal gas recovery directly to the tuyere area, reduce the pollution of the atmosphere, the recovery of coal gas time 9 hours 45 minutes, accounting for 92.56% of the shutdown and material surface time, while the economic benefits of coal gas recovery, this time the cumulative recovery of coal gas 1472406m 3 , this shutdown and material surface from 1 January 13:28, January 7, 0:00 end, 10 hours 32 minutes, shorten the shutdown and material surface time and no explosion during the period, to achieve the purpose of safe, efficient, economic shutdown and material surface, its economic benefits as follows: (1) the amount of coal gas recovery accounted for 97.62% of the total gas, the benefit of 147200 yuan; (2) the process of shutdown and material surface, moderate spraying coal 13:28 air supply, 17:00 stop coal, a total of 93 tons of coal injection, save the coke benefit of 682600 yuan; to achieve the purpose of safe, efficient shutdown and material surface.

Claims

1. A method for stopping a blast furnace empty charge line and lowering the charge level, characterized by comprising 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 appropriately 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 level is at different locations in the blast furnace, the blast furnace top temperature is controlled to varying 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 continuously 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. Control the composition of coal gas (1) The O2 content in the gas shall be controlled within 2.0%; (2) The CO2 content in the gas shall 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 specific details of which are as follows: (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; (2) The blast furnace charge line is lowered to 3.0 meters, and the coke and ore platforms are simultaneously reduced by 3.0°. (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°, maintaining 6 gears and 14 cloth circles.

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) also includes the following: (1) When the material level is above 1 / 2 of the furnace belly, the blast furnace top temperature is controlled at 320-350℃; (2) When the material level is at or below 1 / 2 of the furnace belly, the blast furnace top temperature is 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, The third part of (iv) also includes controlling the temperature of the airtight box at 20.0-24.0℃.

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