Method for restarting blast furnace after scheduled downtime

Abstract

The application discloses a blast furnace post-scheduled blowdown recovery method and relates to the technical field of blast furnaces. Before the blast furnace is blown down, the blast furnace is added with blowdown materials, heat can be supplemented into the blast furnace, the permeability of the material column in the blast furnace is improved, and the recovery time is shortened; after the blast furnace is blown down, all tuyere small sleeves of the blast furnace are sealed, all iron ports of the blast furnace are blocked, the natural heat dissipation of the blast furnace is reduced, the heat in the blast furnace is kept sufficient, and the recovery time is shortened; before the blast furnace is recovered, the tuyere small sleeves of the blast furnace are poked to send air, the poked tuyere small sleeve has a higher air speed, the recovery time is shortened; after the blast furnace is recovered, with the increase of the air volume and the improvement of the permeability of the material column in the blast furnace, the recovery materials are sequentially added into the blast furnace, the iron port is timely opened to discharge slag iron after the air volume reaches a certain level, all tuyere small sleeves in the sealed state are gradually poked, and finally the air volume is recovered to the air volume before the blowdown, so that the recovery time of the blast furnace is greatly shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blast furnaces, and in particular to a method for restarting a blast furnace after a planned shutdown. BACKGROUND

[0002] During blast furnace production, iron ore and coke are charged from the top of the furnace, and hot air is blown into the tuyeres distributed along the circumference of the furnace from the lower part of the furnace. The hot air and coke combustion produces coal gas that moves upward, and the iron ore undergoes a series of physical and chemical processes such as heating, reduction, melting, slagging, carburizing, and desulfurization, and finally generates liquid slag iron, which is discharged from the furnace through the iron notch.

[0003] During production, the blast furnace is shut down for maintenance every certain period of time (e.g., 3-4 months), and the shutdown maintenance time is generally 8-24 hours. After maintenance is completed and the conditions for restarting are met, the blast furnace begins to blow air. After about 20 hours of air blowing, the blast furnace can return to normal operation, i.e., the air flow into the furnace returns to the normal level before the shutdown. The entire recovery process of the blast furnace takes about 20 hours, and there is a problem of long time for restarting. SUMMARY

[0004] The present application provides a method for restarting a blast furnace after a planned shutdown, which solves the technical problem of long time for restarting the blast furnace in the prior art.

[0005] The present application provides the following technical solutions:

[0006] A method for restarting a blast furnace after a planned shutdown, comprising:

[0007] Before the blast furnace is shut down, adding shutdown material into the blast furnace to supplement heat and improve the permeability of the material column in the blast furnace;

[0008] After the blast furnace is shut down, sealing all tuyere sleeves of the blast furnace and plugging all iron notches of the blast furnace;

[0009] At a time point that is a first time length away from the time of restarting the blast furnace, opening part of the tuyere sleeves of the blast furnace;

[0010] After the blast furnace is restarted, gradually increasing the air flow into the blast furnace to a third preset air flow, and then starting to add restart material into the blast furnace;

[0011] Increasing the air flow to a fourth preset air flow and opening one of the iron notches of the blast furnace;

[0012] After the flow rate of the molten iron in the iron notch reaches a preset flow rate and the slag of the blast furnace flows into the slag trench, in the process of gradually increasing the air flow to an eighth preset air flow, sequentially opening all tuyere sleeves in a sealed state;

[0013] increasing the blast volume to the pre-downtime blast volume of the blast furnace.

[0014] Preferably, the downtime material comprises a first material, clean coke, a second material and a third material, the first material, the second material and the third material have a burden lower than a target burden;

[0015] Before the downtime of the blast furnace, adding downtime material into the blast furnace to supplement heat in the blast furnace and improve the permeability of the material column in the blast furnace, comprising:

[0016] Before the downtime of the blast furnace, the first material, the clean coke and the second material are added into the blast furnace in sequence, and finally the third material is added into the blast furnace until the downtime of the blast furnace, so that the clean coke is located at the lower part of the bosh of the blast furnace when the blast furnace is downtime.

[0017] Preferably, after the downtime material is added into the blast furnace to supplement heat in the blast furnace and improve the permeability of the material column in the blast furnace before the downtime of the blast furnace, and after the downtime of the blast furnace, sealing all tuyere small sleeves of the blast furnace, before plugging all iron ports of the blast furnace, further comprising:

[0018] Discharging the last heat of slag and iron before the downtime of the blast furnace.

[0019] Preferably, after the downtime material is added into the blast furnace to supplement heat in the blast furnace and improve the permeability of the material column in the blast furnace before the downtime of the blast furnace, and after the downtime of the blast furnace, sealing all tuyere small sleeves of the blast furnace, before plugging all iron ports of the blast furnace, further comprising:

[0020] After the downtime of the blast furnace, reducing the cooling intensity of the blast furnace.

[0021] Preferably, the sealing of all tuyere small sleeves of the blast furnace comprises:

[0022] Plugging all tuyere small sleeves by water mortar, and smearing butter outside the water mortar.

[0023] Preferably, the gradually increasing the blast volume to the third preset blast volume comprises:

[0024] Increasing the blast volume to a first preset blast volume, and determining whether the blast system is running or leaking;

[0025] If the blast system is normal, increasing the blast volume to a second preset blast volume, leading the gas in the blast furnace to the dust removal system, and taking off the top diffuser;

[0026] After confirming that the top diffuser is taken off, increasing the blast volume to the third preset blast volume.

[0027] Preferably, the reblowing material comprises a fourth material, a fifth material, a sixth material and a seventh material, the load of the fourth material, the fifth material, the sixth material and the seventh material increases in turn, and the load of the seventh material is the target load.

[0028] Preferably, after the flow rate of molten iron of the iron notch reaches the preset flow rate and the slag of the blast furnace flows into the slag trench, the number of the small blast nozzles in the sealed state is three.

[0029] Preferably, after the flow rate of molten iron of the iron notch reaches the preset flow rate and the slag of the blast furnace flows into the slag trench, in the process of gradually increasing the air volume to the eighth preset air volume, all the small blast nozzles in the sealed state are sequentially opened, including:

[0030] After the second time length that the flow rate of molten iron of the iron notch reaches the preset flow rate threshold and the slag of the blast furnace flows into the slag trench, the first small blast nozzle in the sealed state is opened, and the air volume is gradually increased to the sixth preset air volume;

[0031] After the fourth time length that the air volume is increased to the sixth preset air volume, the second small blast nozzle in the sealed state is opened, and the air volume is gradually increased to the eighth preset air volume;

[0032] After the sixth time length that the air volume is increased to the eighth preset air volume, the third small blast nozzle in the sealed state is opened.

[0033] Preferably, the increasing of the air volume to the air volume before the blast furnace is blown down comprises:

[0034] First, the air volume is increased to the ninth preset air volume, and then the air volume is increased to the air volume before the blast furnace is blown down.

[0035] The technical scheme provided by the application has at least the following technical effects or advantages:

[0036] Before the blast furnace is blown down, the blowing-down material is added into the blast furnace, heat can be supplemented into the blast furnace, and the permeability of the material column in the blast furnace is improved, so that the reblowing time is shortened; after the blast furnace is blown down, all the small blast nozzles of the blast furnace are sealed, and all the iron notches of the blast furnace are blocked, so that the natural heat dissipation of the blast furnace is reduced, the heat in the blast furnace is maintained, and the reblowing time is shortened; before the blast furnace is reblown, part of the small blast nozzles of the blast furnace are opened, so that the opened small blast nozzles have a higher air speed, and the reblowing time is shortened; after the blast furnace is reblown, with the increase of the air volume and the improvement of the permeability of the material column in the blast furnace, the reblowing material is sequentially added into the blast furnace, the iron notch is timely opened to discharge slag and iron after the air volume reaches a certain level, and all the small blast nozzles in the sealed state are gradually opened, and finally the air volume is restored to the air volume before the blast furnace is blown down, so that the reblowing time of the blast furnace is greatly shortened. BRIEF DESCRIPTION OF DRAWINGS

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the blast furnace structure in an embodiment of the present invention;

[0039] Figure 2 This is a flowchart of the blast furnace restart method after a planned shutdown, as described in an embodiment of the present invention. Detailed Implementation

[0040] The embodiments of the present invention provide a method for restarting blast furnaces after a planned shutdown, thereby solving the technical problem of long restarting time for blast furnaces in the prior art.

[0041] To better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] like Figure 1 As shown, a blast furnace consists of, from top to bottom, the throat, shaft, waist, belly, and hearth. A ring of tuyeres surrounds the hearth, and a taphole is located below the tuyeres. Generally, iron ore begins to soften in the lower part of the shaft, further melts in the waist and belly, and becomes molten slag-iron in the hearth. This molten slag-iron is discharged from the taphole. During blast furnace production, the furnace is cooled; in this example, the blast furnace uses open-circuit industrial water cooling.

[0043] like Figure 2 As shown, the method for restarting blast furnace after a planned shutdown in this embodiment includes:

[0044] Step S1: Before shutting down the blast furnace, add shutdown material into the blast furnace to replenish heat and improve the permeability of the charge column inside the blast furnace.

[0045] Step S2: After the blast furnace is shut down, seal all the tuyeres of the blast furnace and block all the iron tapholes of the blast furnace.

[0046] Step S3: At the point one hour before the blast furnace restarts, partially open the tuyeres of the blast furnace.

[0047] Step S4: After the blast furnace is blasted back into the furnace, gradually increase the air volume fed into the blast furnace to the third preset air volume, and then start adding blasting material into the blast furnace.

[0048] Step S5: Increase the air volume to the fourth preset air volume and open one of the iron taps of the blast furnace;

[0049] Step S6, after the flow rate of the molten iron at the iron notch reaches the preset flow rate and the slag of the blast furnace flows into the slag pit, in the process of gradually increasing the air volume to the eighth preset air volume, sequentially punch open all the small notches in the sealed state.

[0050] Step S7, increase the air volume to the pre-shutdown air volume of the blast furnace.

[0051] In this embodiment, before step S1, the furnace condition needs to be stable and smooth, the material line needs to be uniform and smooth, and the furnace temperature needs to be stable and sufficient. The quantitative standard is that the silicon content of the molten iron is 0.3-0.5%, the physical heat (i.e. the temperature of the molten iron) is 1480-1500℃, and the slag R2 (i.e. the binary basicity) is between 1.16 and 1.20.

[0052] In step S1, the shutdown material can include a first material, clean coke, a second material, and a third material, as shown in Table 1. The load of the first material, the second material, and the third material is lower than the target load, and the target load is the material load of the blast furnace before shutdown, i.e. the normal load.

[0053] Table 1

[0054]

[0055] The first material, the second material, and the third material all include iron ore and coke. The load of the material is the weight ratio of the iron ore and the coke. When the weight of the iron ore is constant, the smaller the load of the material, the greater the weight of the coke, i.e. the more the amount of coke.

[0056] Step S1 specifically includes: before the blast furnace is shut down, the first material, clean coke, and the second material are sequentially added to the blast furnace, and finally the third material is added to the blast furnace until the blast furnace is shut down, so that the clean coke is located at the lower part of the bosh when the blast furnace is shut down.

[0057] It can be understood that before the blast furnace is shut down, due to the high-temperature hot air being sent in, the shutdown material will burn a part in the furnace, generate heat to increase the temperature in the furnace, facilitate the recovery of the temperature in the furnace during the restart, and be beneficial to shorten the restart time. Since the load of the first material, the second material, and the third material is lower than the target load, the amount of coke is more than that during normal production, and there are gaps between the coals, the permeability of the charge column in the furnace is better during the shutdown, which is beneficial to the gas flow during the restart, and thus is beneficial to shorten the restart time; since the iron ore starts to soften in the lower part of the shaft, the softened slag iron will seep into the gaps between the coals, and the thickness of the coke layer at the bosh position increases and the porosity increases during the shutdown, which also improves the permeability of the charge column in the furnace, which is beneficial to shorten the restart time.

[0058] After step S1 and before step S2 of this embodiment, the method for restarting the blast furnace after the blast furnace is planned to be shut down further includes: draining the last heat of slag iron before the blast furnace is shut down; after the blast furnace is shut down, reducing the cooling intensity of the blast furnace.

[0059] Slag iron is a mixture of slag and molten iron. If the last batch of slag iron before the blast furnace is not discharged, the slag iron may flow into the tuyere small sleeve during the blast furnace downtime, causing tuyere small sleeve and blast pipe slagging accidents. Discharging the last batch of slag iron before the blast furnace downtime can avoid the impact of incomplete slag iron discharge on the blast, thereby shortening the blast time. The standard for slag iron discharge can be 90% higher than the theoretical iron discharge amount. As mentioned above, the blast furnace is cooled during production, and a significant drop in temperature after downtime is not conducive to temperature recovery during the blast. Reducing the cooling intensity of the blast furnace after downtime can prevent the temperature from dropping too much, which is conducive to the recovery of the furnace temperature during the blast and can shorten the blast time. After the blast furnace is stopped, the cooling intensity of the blast furnace can be reduced to 1 / 4 of the normal cooling intensity.

[0060] In step S2, sealing all tuyere small sleeves of the blast furnace can include: blocking all tuyere small sleeves with water mortar, and applying butter outside the water mortar. The application of butter outside the water mortar can increase the sealing performance. Sealing all tuyere small sleeves of the blast furnace and blocking all iron ports of the blast furnace can reduce the natural heat dissipation of the blast furnace, thereby facilitating the recovery of the furnace temperature during the blast and shortening the blast time.

[0061] This embodiment takes a blast furnace with 20 blast tuyeres and 2 iron ports as an example. The 20 blast tuyeres are evenly distributed around the hearth. If viewed from the top of the blast furnace, the 2 iron ports are located at the northwest and southwest sides of the hearth, respectively, with an included angle of 80°. The first time length can be 30 minutes. In step S3, 17 tuyere small sleeves are opened 30 minutes before the blast furnace is blown, and the remaining 3 tuyere small sleeves in the north, east, and south directions are still sealed. Since the blast volume is small when the blast furnace is just blown, opening only part of the tuyere small sleeves for blast can make the blast speed of the tuyere small sleeve higher, which is conducive to shortening the blast time.

[0062] In step S4, gradually increasing the blast volume to the third preset blast volume can include: increasing the blast volume to the first preset blast volume, and determining whether the blast system is leaking; if the blast system is normal, increasing the blast volume to the second preset blast volume, leading the coal gas in the blast furnace to the dust removal system, and releasing the top of the furnace; after confirming that the top of the furnace is released and tightened, increasing the blast volume to the third preset blast volume.

[0063] The first preset blast volume can be 40% of the normal blast volume, the second preset blast volume can be 50% of the normal blast volume, and the third preset blast volume can be 60% of the normal blast volume. First, increase the blast volume to the first preset blast volume, which is small, and it is conducive to handling the air leakage of the blast system for blast.

[0064] The reblowing material includes a fourth material, a fifth material, a sixth material, and a seventh material. The loads of the fourth material, the fifth material, the sixth material, and the seventh material are sequentially increased, and the load of the seventh material is the target load, as shown in Table 2. The sequence of the charging is the fourth material, the fifth material, the sixth material, and the seventh material. The sixth material needs to be added to the air volume reaching 80% of the normal air volume, and the seventh material needs to be added to the air volume reaching the normal air volume. Similar to the principle of the blowing-off material, the reblowing material can supplement the heat in the furnace and improve the permeability, thereby shortening the reblowing time. The first 5 batches of reblowing material can be manually controlled to be loaded into the furnace, and the material is loaded according to the hot blast pressure and the furnace top temperature. The loading speed is slower than the normal loading speed. After the manual control of the loading of the 5 batches of material, the automatic loading and chasing line can be set.

[0065] Table 2

[0066]

[0067] In step S5, the fourth preset air volume can be 70% of the normal air volume. The embodiment will increase the air volume to the fourth preset air volume after starting to load 2-3 batches of reblowing material.

[0068] During the process of increasing the air volume from the third preset air volume to the fourth preset air volume, since the air volume is still small, the amount of slag iron generated by the melting of the reblowing material is not much, and the iron notch is continuously kept blocked. After the air volume is increased to the fourth preset air volume, the amount of slag iron generated is relatively large, so the iron notch needs to be opened in time to discharge the melted slag iron (molten iron). The subsequent iron tapping organization needs to open the iron notch of the next furnace in 20-25 minutes after blocking the iron notch according to the requirements of the normal production iron tapping organization, which is beneficial to safely and timely tapping out of the slag iron and shortening the reblowing time.

[0069] In the embodiment, after the molten iron flow rate of the iron notch reaches the preset flow rate and the blast furnace slag flows into the slag trench, the number of tuyere small sleeves in the sealed state is three. Step S6 can specifically include: after the molten iron flow rate of the iron notch reaches the preset flow rate threshold and the second time length of the blast furnace slag flowing into the slag trench, the first tuyere small sleeve in the sealed state is poked open, and the air volume is gradually increased to the sixth preset air volume; after the fourth time length of increasing the air volume to the sixth preset air volume, the second tuyere small sleeve in the sealed state is poked open, and the air volume is gradually increased to the eighth preset air volume; after the sixth time length of increasing the air volume to the eighth preset air volume, the third tuyere small sleeve in the sealed state is poked open. Gradually increasing the air volume to the sixth preset air volume can include: first increasing the air volume to the fifth preset air volume, and after the third time length of increasing the air volume to the fifth preset air volume, increasing the air volume to the sixth preset air volume. Gradually increasing the air volume to the eighth preset air volume can include: first increasing the air volume to the seventh preset air volume, and after the fifth time length of increasing the air volume to the seventh preset air volume, increasing the air volume to the eighth preset air volume.

[0070] The second time length, the third time length, the fourth time length, the fifth time length and the sixth time length can be 10 minutes, 10 minutes, 10 minutes, 5 minutes and 5 minutes in sequence; the fifth preset air volume, the sixth preset air volume, the seventh preset air volume and the eighth preset air volume can be 75%, 80%, 85% and 90% of the normal air volume in sequence. The furnace top pressure needs to be matched and adjusted during the whole air adding process, and the pressure difference is kept to be less than or equal to 160 kpa (hot air pressure-furnace top pressure); before the air volume is restored to 90%, the hot air temperature is slightly lower than that in the normal condition, so as to ensure the appropriate pressure-volume relationship and create conditions for preferentially restoring the air volume; in this process, the oxygen enrichment amount and the coal amount are matched and increased.

[0071] In step S6, the three blocked tuyere small sleeves are sequentially poked open with the increase of the air volume. The increase of the air volume can increase the air speed of the air supply tuyere small sleeve close to the air speed in the normal production, and sequentially poked open the blocked tuyere small sleeve, so that the air supply area is increased, which in turn is beneficial to increase the air volume, so as to accelerate the recovery process and shorten the air recovery time.

[0072] Step S7 can specifically include: first increasing the air volume to a ninth preset air volume, and then increasing the air volume to the air volume before the blast furnace is blown out. The ninth preset air volume can be 95% of the normal air volume. The air volume can be increased to 100% of the normal air volume (air volume before blowing out) of the blast furnace after 5 minutes of increasing the air volume to the ninth preset air volume.

[0073] The time comparison of the air recovery process in the above and the traditional air recovery process is shown in Table 3. It can be seen that the air recovery method of the embodiment can shorten the air recovery time to 5-6 hours.

[0074] Table 3

[0075]

[0076] As can be seen from the above, the air recovery method of the blast furnace after planned blowing out in the embodiment can add blowing-out material into the blast furnace before the blast furnace is blown out, can supplement the heat in the blast furnace and improve the permeability of the material column in the blast furnace, and can shorten the air recovery time; after the blast furnace is blown out, all tuyere small sleeves of the blast furnace are sealed, and all iron ports of the blast furnace are blocked, which can reduce the natural heat dissipation of the blast furnace, is beneficial to maintaining sufficient heat in the blast furnace, and can shorten the air recovery time; before the blast furnace is blown in, part of the tuyere small sleeves of the blast furnace are poked open for air supply, which can make the air speed of the poked open air supply tuyere small sleeve higher, and is beneficial to shorten the air recovery time; after the blast furnace is blown in, with the increase of the air volume and the improvement of the permeability of the material column in the blast furnace, the air recovery material is sequentially added into the blast furnace, the iron port is timely opened to discharge the slag and iron after the air volume reaches a certain level, and all tuyere small sleeves in the sealed state are gradually poked open, and finally the air volume is restored to the air volume before blowing out, which greatly shortens the air recovery time of the blast furnace.

[0077] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims include all such modifications and variations as fall within the scope of the present application.

[0078] It is apparent that those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. It is therefore intended that the present application cover all such changes and modifications that are within its scope.

Claims

1. A method for resuming blast in a blast furnace after a planned blast outage, characterized in that The method comprises the following steps: Before the blast furnace is blown down, a blowing-down material is added into the blast furnace to supplement heat in the blast furnace and improve the permeability of the column in the blast furnace; the blowing-down material comprises a first material, clean coke, a second material and a third material, and the load of the first material, the second material and the third material is lower than a target load; After the blast furnace is blown down, all tuyere small covers of the blast furnace are sealed, and all iron tapholes of the blast furnace are blocked; At a time point which is a first time length away from the time when the blast furnace is blown up, part of the tuyere small covers of the blast furnace are poked open; After the blast furnace is blown up, the air volume is increased to a first preset air volume, and it is judged whether the air supply system is running or leaking; If the air supply system is normal, the air volume is increased to a second preset air volume, the gas in the blast furnace is led to a dust removal system, and the top is tapped to diffuse; The air volume into the blast furnace is gradually increased to a third preset air volume, and then the blowing-up material is started to be added into the blast furnace; The air volume is increased to a fourth preset air volume, and one of the iron tapholes of the blast furnace is opened; After the flow rate of the molten iron of the iron taphole reaches a preset flow rate and the slag of the blast furnace flows into a slag pit, in the process of gradually increasing the air volume to an eighth preset air volume, all tuyere small covers in a sealed state are sequentially poked open; the number of tuyere small covers in a sealed state is three; The air volume is increased to the air volume before the blast furnace is blown down; Sealing all tuyere small covers of the blast furnace, comprising: All tuyere small covers are blocked by water mortar, and butter is applied outside the water mortar; After the flow rate of the molten iron of the iron taphole reaches a preset flow rate and the slag of the blast furnace flows into a slag pit, in the process of gradually increasing the air volume to an eighth preset air volume, all tuyere small covers in a sealed state are sequentially poked open, comprising: After the flow rate of the molten iron of the iron taphole reaches a preset flow rate threshold and the slag of the blast furnace flows into a slag pit for a second time length, the first tuyere small cover in a sealed state is poked open, and the air volume is gradually increased to a sixth preset air volume; After a fourth time length of increasing the air volume to the sixth preset air volume, the second tuyere small cover in a sealed state is poked open, and the air volume is gradually increased to the eighth preset air volume; After a sixth time length of increasing the air volume to the eighth preset air volume, the third tuyere small cover in a sealed state is poked open.

2. The blast furnace post-scheduled outage blowback method of claim 1, wherein, Before the blast furnace is blown down, a blowing-down material is added into the blast furnace to supplement heat in the blast furnace and improve the permeability of the column in the blast furnace, comprising: Before the blast furnace is blown down, the first material, the clean coke and the second material are sequentially added into the blast furnace, and finally the third material is added into the blast furnace, until the blast furnace is blown down, so that the clean coke is located at a lower position of the bosh of the blast furnace when the blast furnace is blown down.

3. The blast furnace post-scheduled outage blowback method of claim 1, wherein, After the step of adding the blowing-down material into the blast furnace before the blast furnace is blown down to supplement heat in the blast furnace and improve the permeability of the column in the blast furnace, and before the step of sealing all tuyere small covers of the blast furnace and blocking all iron tapholes of the blast furnace after the blast furnace is blown down, the method further comprises the following step: The last furnace slag and iron of the blast furnace before the blast furnace is blown down is discharged.

4. The blast furnace post-scheduled outage blowback method of claim 1, wherein, Before the blast furnace is blown down, the blast furnace is charged with a blow-down material to supplement heat in the blast furnace and improve the permeability of the column in the blast furnace, and after the blast furnace is blown down, all tuyere small sleeves of the blast furnace are sealed, and all iron ports of the blast furnace are blocked before all tuyere small sleeves of the blast furnace are sealed. After the blast furnace is blown down, the cooling intensity of the blast furnace is reduced.

5. The blast furnace post-outage blowback method of claim 1, wherein, The gradually increasing the amount of air sent into the blast furnace to the third preset air volume comprises: After confirming that the top diffuser is tightened, the air volume is increased to the third preset air volume.

6. The blast furnace post-outage blowback method of claim 1, wherein, The blow-in material comprises a fourth material, a fifth material, a sixth material and a seventh material, the loads of the fourth material, the fifth material, the sixth material and the seventh material are sequentially increased, and the load of the seventh material is a target load.

7. The blast furnace post-outage blowback method of claim 1, wherein, Increasing the air volume to the pre-blow-down air volume of the blast furnace comprises: First, the air volume is increased to a ninth preset air volume, and then the air volume is increased to the pre-blow-down air volume of the blast furnace.

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