High-titanium slag blast furnace recovery method

Abstract

This disclosure relates to the field of high-titanium slag blast furnace smelting technology, and particularly to a method for restoring a high-titanium slag blast furnace after a shutdown. The method includes: reducing the coke load by 13% to 18% 4-5 hours before the shutdown; adding clean coke 3-4 hours before the shutdown, and adjusting the charging system to: a 3-ring ore charging system, with the ore platform's radial angle width ranging from 3° to 4°, the outer coke-ore angle difference ranging from 1.5° to 2°, and the inner ore-coke angle difference ranging from 5.5° to 6°; and controlling the pig iron [Ti] content to 0.15% to 0.20% and the slag binary basicity to 1.04 to 1.08 times the standard basicity starting 1-2 hours before the shutdown. This disclosure allows for rapid restarting of a high-titanium slag blast furnace after a long shutdown.

Description

Technical Field

[0001] This disclosure relates to the field of high-titanium slag blast furnace smelting technology, and in particular to a method for restoring high-titanium slag blast furnace after shutdown. Background Technology

[0002] In ordinary blast furnace slag, the TiO2 content is usually very low (<1%); however, when smelting vanadium-titanium magnetite, the TiO2 content in blast furnace slag will increase significantly. When the TiO2 content in blast furnace slag reaches more than 22.5%, a large number of high-melting-point Ti(CN) solid particles will precipitate.

[0003] Blast furnace production is continuous under normal conditions, but sometimes it needs to be shut down (stopped from blowing) for 6 to 15 hours due to equipment failure or planned reasons. During the shutdown, the furnace temperature drops. If the slag contains a large amount of high-melting-point Ti(CN), the viscous slag-iron mixture in the hearth will solidify severely when the shutdown time is long (more than 6 hours). When the blast furnace resumes production after shutdown, the operators will increase the air volume to raise the furnace temperature and melt the solidified material. However, if the air volume is increased too quickly, the tuyeres will be damaged or "slag-filled" due to obstruction in the vortex zone. If the air volume is increased too slowly, the hearth cannot be heated to a sufficient temperature to melt the high-melting-point Ti(CN) hard shell. Therefore, the operators will repeatedly increase the air volume, stabilize it for a period of time, and then increase it again, which greatly affects the recovery progress. Under normal circumstances, a regular blast furnace can resume normal production within a few hours after shutting down; however, a blast furnace with high titanium slag (TiO2>22.5%) often takes several days or even more than a week to recover after shutting down, and cannot quickly return to full production like a regular blast furnace.

[0004] Based on the above, the existing methods for restoring high-titanium slag blast furnaces after shutdown need further improvement. Summary of the Invention

[0005] The purpose of this disclosure is to enable high-titanium slag blast furnaces to be quickly restarted in a short period of time after a long period of shutdown.

[0006] To address the aforementioned technical problems, this disclosure provides a method for restoring a high-titanium slag blast furnace after a shutdown, comprising the following steps before shutdown: The coke load is reduced by 13% to 18% starting 4 to 5 hours before the shutdown. 3-4 hours before the shutdown, add clean coke and adjust the material distribution system to: 3-ring ore material system, the width of the ore platform in the radial angle range of 3°~4°, the outer coke-ore angle difference range of 1.5°~2°, and the inner coke-ore angle difference range of 5.5°~6°. One to two hours before shutting down the furnace, the pig iron [Ti] content should be controlled within the range of 0.15% to 0.20%, and the slag binary basicity should be controlled within the range of 1.04 to 1.08 times.

[0007] In some embodiments, when adding clean coke, if the blast furnace volume is ≤1500 m³ 3 Then add one set of clean coke every 25-35 minutes, for a total of 4-5 sets, until the total amount of clean coke added reaches 12t-15t; if 1500 m 3 Blast furnace volume ≤ 2000 m³ 3 Then, add one set of clean coke every 5 to 7 batches of material, for a total of 4 to 5 sets of clean coke, until the total amount of clean coke added reaches 43t to 50t.

[0008] In some embodiments, the high-titanium slag blast furnace shutdown recovery method further includes the following shutdown step: When the iron tapping process begins and the tapping process is interrupted, oxygen enrichment is stopped and the air pressure is reduced. At the same time, the ore batch weight is reduced by 12% to 18% from the normal level.

[0009] In some embodiments, the ventilation stoppage step further includes: If there are damaged cooling walls, reduce water flow until the shutdown process is complete.

[0010] In some embodiments, the high-titanium slag blast furnace shutdown recovery method further includes: After the ventilation shutdown process is completed, reduce the diameter of the air vent rings of 2-3 air vents by 1 / 12 to 3 / 14.

[0011] In some embodiments, the high-titanium slag blast furnace shutdown recovery method further includes the following initial restart step: Before material movement, control the air pressure to not exceed 0.1 MPa and prohibit feeding. After the material is moved, maintain the furnace top temperature at 250℃~300℃ and start feeding. Control the air pressure to not exceed 0.11MPa, and organize the tapping of iron in front of the furnace.

[0012] In some embodiments, during the initial re-airing step, if the furnace top temperature exceeds 350°C to 400°C before material movement, water is sprayed from the furnace top to reduce the furnace top temperature.

[0013] In some embodiments, the high-titanium slag blast furnace shutdown recovery method further includes the following post-shutdown blast furnace restart step: Once the feed line is operating normally, the material feeding is continuous and uniform, and the furnace top temperature is stable, begin increasing the air supply, with each increase not exceeding 50m³. 3 / min, the air pressure rise should not exceed 5kPa; before feeding 30-35 batches of air, the difference between the hot air pressure and the furnace top pressure should not exceed 0.12MPa. After feeding 30-35 batches, the coke load should be gradually restored to normal according to the furnace temperature. When the air volume is increased to 80% of the normal air volume, the normal material system should be restored and oxygen enrichment should be started. The ore batch weight should be gradually restored from the recovery ore batch weight during the shutdown to the normal ore batch weight according to the air volume.

[0014] In some embodiments, during the later re-airing step, if the air pressure rises above a predetermined value before 30-35 batches of air are supplied, the air temperature is withdrawn by 100°C-200°C.

[0015] In some embodiments, after the air volume is increased to 80% of the normal air volume, if the ratio of air volume to air pressure is less than a predetermined ratio, the air vent ring of one of the two to three air vents whose diameter has been reduced by 1 / 12 to 3 / 14 is restored to the diameter before the air vent was shut down, thereby increasing the air vent area.

[0016] The above technical solution has at least the following beneficial effects: This disclosure discloses a method for restoring a high-titanium slag blast furnace after a shutdown. This method increases the hearth heat reserve by reducing the coke load and adding clean coke before the shutdown. It also strengthens the central airflow by adjusting the charging system to ensure the permeability of the charge column, creating conditions for restarting the blast furnace. Before the shutdown, the pig iron [Ti] content is in the range of 0.15%~0.20% to ensure sufficient heat in the hearth. The slag binary basicity is in the range of 1.04 to 1.08 times to reduce slag viscosity and melting temperature. Thus, during the shutdown, the hearth can be in an ideal state of high temperature, low viscosity, and central airflow, ensuring rapid recovery after a long shutdown and avoiding repeated blasting. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for restoring a high-titanium slag blast furnace after a shutdown, provided in one embodiment of this disclosure. Detailed Implementation

[0019] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0020] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0021] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0022] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0023] As mentioned in the background section above, after a blast furnace with high titanium slag (TiO2>22.5%) is shut down, the recovery time often takes several days or even more than a week, and it cannot be quickly restored to full blast status like a normal blast furnace in a short period of time. Based on this, this disclosure provides a method for restoring a blast furnace with high titanium slag after a shutdown, which can enable a blast furnace with high titanium slag to recover quickly after a long shutdown.

[0024] like Figure 1 As shown, the high-titanium slag blast furnace shutdown recovery method provided in this disclosure can perform the following steps before shutdown: S100, 4-5 hours before shutdown, coke load is reduced by 13%-18%; S200, 3-4 hours before the shutdown, start adding clean coke and adjust the material distribution system to: 3 ring material system for ore, the width range of the ore platform in the radial angle is 3°~4°, the outer coke ore angle difference range is 1.5°~2°, and the inner coke ore angle difference range is 5.5°~6°. For S300 furnaces, 1-2 hours before shutdown, the pig iron [Ti] content should be controlled within the range of 0.15%-0.20%, and the slag binary basicity should be controlled within the range of 1.04-1.08 times.

[0025] Here, coke load refers to the combustion burden of coke, and its calculation formula is the weight of ore in each batch of furnace charge / the weight of coke in each batch of furnace charge. A lighter coke load means an increase in the proportion of coke and a decrease in the proportion of ore. After the furnace charge is loaded from the top, it needs to go through several hours of descent, heating, and reaction before reaching the hearth (i.e., the area where slag and iron are stored). Adjusting the coke load 4 to 5 hours before the shutdown is to ensure that at the moment of shutdown (i.e., when the blast is stopped), a batch of "high coke, low ore" furnace charge has just reached the hearth area, reserving sufficient heat and reducing agent for the upcoming shutdown period.

[0026] Here, clean coke, also called bare coke, refers to coke added to the furnace alone without any ore. In the smelting of high-titanium slag, the amount of slag itself is a burden. If the load is reduced without adding clean coke, although the coke ratio is increased, slag will still be produced with each batch of material. This slag still contains TiO2, and Ti(CN) will still precipitate when the temperature drops, causing problems. Therefore, clean coke can be added 3 to 4 hours before the blast furnace is shut down. This way, the hearth temperature can be further increased without increasing the amount of new slag, and the remaining slag and iron can be "heated, melted, and vented".

[0027] Here, the amount of clean coke added can be determined according to the furnace volume. Generally, 2 to 6 sets of clean coke (each set can range from several tons to more than ten tons) can be added.

[0028] In one possible implementation, when adding clean coke, if the blast furnace volume is ≤1500 m³ 3 Then, add one set of clean coke every 25-35 minutes, for a total of 4-5 sets, until the total amount of clean coke added reaches 12-15 tons. At this point, each set of clean coke will weigh approximately 3 tons. If 1500 m 3 Blast furnace volume ≤ 2000 m³ 3 Then, add one set of clean coke every 5 to 7 batches of material, for a total of 4 to 5 sets of clean coke, until the total amount of clean coke added reaches 43 to 50 tons. At this point, each set of clean coke is about 10 tons.

[0029] Here, while adding clean coke, the feeding system also needs to be adjusted to: a 3-ring feeding system for ore, an ore platform of 3°~4°, an outer coke-ore angle difference of 1.5°~2°, and an inner ore-coke angle difference of 5.5°~6°. That is, during the feeding process, the ore is distributed in three different ring positions (i.e., radial angles). The relatively flat ore platform formed by the ore feeding has a radial angle width of 3° to 4°; the outer coke-ore angle difference, that is, in the outermost feeding ring position, the coke feeding angle is 1.5°~2° larger than the ore feeding angle; the inner ore-coke angle difference, that is, in the innermost feeding ring position, the coke feeding angle is 5.5°~6° smaller than the ore feeding angle. It should be noted that, to achieve the above-mentioned material distribution system, the number of ore rings can be set to 03340, and the number of coke rings to 40124. This means there is no ore at the edge (ring 1) and center (ring 5) (i.e., the number of ore rings is 0); the ore is concentrated in the middle rings 2, 3, and 4, with 3, 3, and 4 rings respectively. For coke, at the edge (ring 1): 4 rings of coke are distributed; this is the outermost coke, which can achieve the angle difference between the outer coke and ore, ensuring sufficient coke at the edge. Ring 2: 0 rings are distributed. A transition zone, with little or no coke, is designed to create a "barrier" on the outside of the ore platform, allowing airflow to be more concentrated from ring 1 (edge) and rings 3-5 (center side); rings 3 and 4: 1 and 2 rings of coke are placed respectively; the amount of coke increases from the outside to the inside, forming support for the ore layer and supplementing the airflow; center (ring 5): 4 rings of coke are placed; combined with the 5.5°~6° difference in the inner ore-coke angle, the strength and height of the central coke pile are ensured, forming a strong central airflow channel.

[0030] Here, to delay the hearth freezing, the requirements of high furnace temperature and low basicity must be met before the blast furnace shutdown. This requires controlling the pig iron [Ti] content to be within the range of 0.15% to 0.20% to meet the high furnace temperature requirement, so as to provide sufficient heat to resist the cooling during the shutdown. At the same time, the binary basicity of the slag must be reduced to 1.04 to 1.08 times to meet the low basicity requirement, so as to reduce the slag viscosity and melting temperature, so that the slag and iron can maintain fluidity for a longer period of time even during the slow cooling process. In this way, the two work together to delay the hearth freezing after the shutdown to the greatest extent.

[0031] This implementation method increases the hearth heat reserve by reducing the coke load and adding clean coke before the shutdown. It strengthens the central airflow by adjusting the charging system to ensure the permeability of the charge column and create conditions for restarting the ventilation. Before the shutdown, the pig iron [Ti] content is in the range of 0.15% to 0.20% to ensure sufficient heat in the hearth. The slag binary basicity range is 1.04 to 1.08 times to reduce slag viscosity and melting temperature. In this way, the hearth can be in an ideal state of high temperature, low viscosity and central ventilation during the shutdown, which can ensure that the ventilation can be quickly restored after a long shutdown and avoid repeated ventilation.

[0032] In one possible implementation, the high-titanium slag blast furnace shutdown recovery method further includes the following shutdown step: When the iron tapping process begins and the tapping process is interrupted, oxygen enrichment is stopped and the air pressure is reduced. At the same time, the ore batch weight is reduced by 12% to 18% from the normal level.

[0033] In this embodiment, "tap blowing" refers to the phenomenon that the substance flowing out of the tap during the tapping process changes from liquid slag and iron to gas (coal gas). When tap blowing occurs in the later stage of tapping, it means that the liquid slag and iron in the hearth has been basically emptied and coal gas begins to spray out of the tapping channel. At this time, the blast shutdown operation can be started, that is, the oxygen enrichment is stopped and the blast and pressure are reduced to steadily reduce the smelting intensity.

[0034] In this implementation, after the shutdown begins, the ore batch weight is adjusted by reducing it by 12% to 18% from the normal value. Ore batch weight refers to the total weight of ore in each batch of furnace charge; that is, after the shutdown, the weight of ore in each batch of furnace charge is reduced by 12% to 18%. A reduced ore batch weight means less slag produced in each subsequent batch of furnace charge, and a lighter load on the charge column in the furnace belly and waist areas. This helps maintain a loose charge column during the shutdown, preventing deterioration of permeability due to gravity compaction. Moreover, after the shutdown, the amount of ore in the remaining charge column in the furnace is reduced, and the proportion of coke is relatively increased, making it easier to heat and blow through during the restart, which is beneficial for rapid recovery after the shutdown.

[0035] In one possible implementation, the ventilation stoppage step further includes: If there are damaged cooling walls, reduce water flow until the shutdown ends.

[0036] In this embodiment, a damaged cooling wall refers to a situation where the cooling wall of the blast furnace body is broken, leaking water, or has a reduced cooling effect. If there is a damaged cooling wall, the cooling water flow rate of the cooling wall can be reduced instead of immediately stopping the water supply. This can avoid the sudden temperature rise of the cooling wall due to water interruption, which could lead to the slag peeling off the furnace wall or even the cooling wall bursting. The water supply can be stopped only after the blast furnace shutdown is completed. After the blast furnace shutdown, there is no pressure or airflow in the furnace, which makes it safer to deal with the damaged cooling wall.

[0037] In one possible implementation, the high-titanium slag blast furnace shutdown recovery method further includes: After the ventilation shutdown ends, reduce the diameter of the air vent rings of 2-3 air vents by 1 / 12 to 3 / 14.

[0038] In this embodiment, after the shutdown process, 2-3 tuyeres can be selected, and their diameter can be reduced. This reduces the temporary tuyere area, while the remaining tuyeres remain unchanged. By reducing the diameter of 2-3 tuyeres during the shutdown period, the air velocity at these 2-3 reduced-diameter tuyeres is significantly higher than at other tuyeres during the restart. This allows for a high-penetration airflow to initially impact, flush, and activate the dead material column in the center of the furnace hearth. Once the center is initially cleared, the swirling zones of other conventional tuyeres can gradually extend towards the center, forming a virtuous cycle of center-edge synergistic activation, facilitating rapid restart.

[0039] For example, the diameter of the air vent ring of a normal air vent is 140mm or 120mm, and the diameter of the air vent ring can be reduced to 110mm.

[0040] In one possible implementation, the high-titanium slag blast furnace shutdown recovery method further includes the following initial restart step: Before material movement, control the air pressure to not exceed 0.1 MPa and prohibit feeding. After the material is moved, maintain the furnace top temperature at 250℃~300℃ and start feeding. Control the air pressure to not exceed 0.11MPa, and organize the tapping of iron in front of the furnace.

[0041] In this embodiment, during the shutdown period, there is still some solidified or semi-solidified slag and iron in the hearth, and the permeability of the material column is extremely poor. When restarting the blast furnace in the initial stage, the air pressure should be controlled below 0.1 MPa, and a "weak airflow" should be used to tentatively blow the hearth to gradually heat and melt the solidified layer. If the air pressure is too high in the initial stage of restarting the blast furnace, the air volume cannot penetrate the material column and will all flow back out from the tuyeres with the least resistance, causing slag to be poured into the tuyeres, burn through, or even cause an explosion.

[0042] In this embodiment, after the blast furnace is restarted, the hearth begins to regain its air and liquid permeability, and the dead charge column begins to activate. After a period of restarting (approximately 40-70 minutes), the charge (ore and coke) begins to show obvious downward movement under the action of gravity. Before the charge moves, the charge column in the furnace is stationary. If charge is forcibly added at this time, it will further compress the charge column, increase the weight and resistance of the charge column, and make the downward movement, which is already difficult to start, even more difficult. Therefore, charging is prohibited before the charge moves. After the material movement begins, the dead material column in the hearth is not yet fully activated, the central channel is intermittently blocked, and some solidified slag and iron remain in the column, hindering uniform material feeding. Therefore, the material flow is poor, possibly descending intermittently or locally. At this time, the furnace top temperature can be maintained at 250℃~300℃, and charging can begin. Charging should continue the low-load, small-batch charging principle from before the shutdown, slowly and at a low speed. Once charging resumes and the furnace top temperature stabilizes at 250~300℃, the blast pressure can be slightly increased, but not exceeding 0.11MPa to avoid accidents. During the blast recovery process, once a certain amount of liquid slag and iron has accumulated in the hearth, tapping should be organized promptly. This allows for a gradual establishment of the matching between material movement and airflow, timely slag and iron removal, and prevention of secondary freezing.

[0043] In one possible implementation, during the initial re-airing step, if the furnace top temperature exceeds 350°C to 400°C before material movement, water can be sprayed onto the furnace top in an appropriate amount to reduce the furnace top temperature.

[0044] In one possible implementation, the high-titanium slag blast furnace shutdown recovery method further includes the following post-shutdown blast furnace restart step: Once the feed line is operating normally and the furnace top temperature is stable, begin increasing the air supply, with each increase not exceeding 50m³. 3 / min, the air pressure rise should not exceed 5kPa; before feeding 30-35 batches of material, the air pressure difference should not exceed 0.12MPa. After feeding 30-35 batches, the coke load should be gradually restored from before the shutdown to normal according to the furnace temperature. When the air volume is increased to 80% of the normal air volume, the normal material system should be restored and oxygen enrichment should be started. The ore batch weight should be gradually restored from the recovery ore batch weight at the shutdown to normal according to the air volume.

[0045] In this implementation, "normal material line" means that the material level in the furnace (which can be confirmed by detection or calculation) has returned to the normal set value. This indicates that the material column has started to descend uniformly as a whole, without localized material bridging or hanging. "Continuous and uniform feeding" means that the furnace material can descend continuously and uniformly after feeding, without "intermittent movement". This indicates that the dead material column in the hearth has been basically activated, and the air and liquid permeability tends to be stable. "Stable furnace top temperature" means that the furnace top temperature is stable within a certain range and no longer fluctuates drastically. This indicates that the gas distribution and feeding speed are initially matched, and there is no pipeline travel or localized airflow penetration. The three conditions of normal material line, continuous and uniform feeding, and stable furnace top temperature are necessary prerequisites for safe blasting.

[0046] In this implementation, the incremental air supply is extremely small, not exceeding 50m³ per cycle. 3 / min, which is equivalent to 1 / 5 to 1 / 10 of the air volume added during normal production, allows for fine-tuning to test the furnace hearth and material column's capacity, preventing sudden increases in air volume from causing airflow turbulence or tuyeres damage. The increase in air pressure after each air addition must not exceed 5 kPa.

[0047] In this embodiment, from the start of resuming feeding after the air is turned on until 30 to 35 batches of furnace charge are loaded (usually within a few hours after the air is turned on), the difference between the hot air pressure and the furnace top pressure (i.e., the pressure differential) is controlled to not exceed 0.12 MPa. Strict control of the pressure differential is to prevent the airflow from forcibly penetrating local weak points to form a pipe.

[0048] In this implementation, after about 30 to 35 batches of furnace charge being carried down and replaced, the special material system adjusted before the shutdown (load reduction, addition of clean coke, narrow platform, etc.) has been basically replaced by the newly charged furnace charge. The state of the hearth and charge column tends to be normal. At this time, the coke load (ore / coke ratio) can be gradually restored from the low load state before the shutdown to the normal value. The increase in coke load should not be too large each time to avoid the furnace temperature from dropping or rising suddenly due to the rapid increase in coke load. After each increase, the furnace temperature, pressure difference, and charge situation should be observed, and the process can continue after stabilization.

[0049] In this embodiment, when the air volume is increased to 80% of the normal air volume, it indicates that the hearth has achieved good permeability and thermal condition, and the dead material column is basically activated. At this point, the normal feed composition can be restored, and oxygen enrichment can begin. Since the batch weight of the ore (total weight of each batch of furnace charge) is reduced by 12% to 18% during the shutdown to reduce the load on the charge column, the batch weight of the ore can be gradually restored as the air volume is gradually restored, ensuring that parameters such as the ore-to-coke ratio and slag quantity match the air volume.

[0050] In one possible implementation, during the later re-airing step, if the air pressure exceeds a predetermined value before 30-35 batches of air are supplied, the air temperature is withdrawn by 100°C-200°C.

[0051] In this embodiment, during the later re-airing step, when the air pressure exceeds a predetermined value, such as a sudden and unexpected increase (e.g., the air pressure increases by more than 5 kPa or the air pressure increases to the point that the pressure difference approaches the upper limit of 0.12 MPa), the gas volume can be reduced and the airflow velocity can be reduced by lowering the air temperature, thereby reducing the air pressure without reducing the air volume.

[0052] In one possible implementation, after the air volume is increased to 80% of the normal air volume, if the ratio of air volume to air pressure is less than a predetermined ratio, the air vent ring of one of the two or three air vents whose diameter has been reduced by 1 / 12 to 3 / 14 is restored to the diameter before the air vent was shut down, thereby increasing the air vent area.

[0053] In this implementation, during the latter half of the air recovery process, when the air volume has recovered to more than 80% of its normal value, the furnace temperature is normal and the operation is smooth (i.e., the material feeding is uniform, the furnace top temperature is stable, and the pressure difference is within a controllable range). Under normal conditions, increasing the air volume should result in a steady increase in air pressure. If the ratio of air volume to air pressure is less than the predetermined ratio, it indicates that the air pressure is rising too quickly. In this case, one of the tuyeres whose diameter was reduced before the shutdown can be restored to its original diameter. This increases the total air intake area, making it easier for the air volume to pass through, thereby reducing the hot air pressure and alleviating the pressure-volume relationship.

[0054] Using the blast furnace shutdown recovery method for high-titanium slag provided in this disclosure, during the blast furnace smelting process of high-titanium slag (TiO2 content 22.5%), the blast furnace blast volume can be restored to normal production level within 6-12 hours after a blast furnace shutdown of 6-15 hours and after the blast is restored; the following uses a blast furnace (1350m³) as an example. 3 The following example illustrates the situation: ventilation was resumed 10 hours after a ventilation shutdown.

[0055] I. Operations before wind cessation 1. During normal production, the ore batch weight is 32t, the coke load is 4.660t / t, and the feed composition is as follows (α represents the feed angle, O represents ore, and C represents coke):

[0056] 2. The blast furnace is scheduled to shut down at 9:00 AM, and the feedstock will be changed starting at 4:00 AM (5 hours before the shutdown), with the coke load reduced to 4.00 t / t (a 14% reduction in coke load). 3. At 5:30 (3.5 hours before the ventilation shutdown), adjust the material distribution system. The ore 3-ring distribution system is shown in the table below. At this time, the ore platform is 4°, the outer coke angle difference is 1.5°, and the inner coke angle difference is 6°.

[0057] 4. At 5:30 (3.5 hours before the wind stop), add 12 tons of clean coke (3.0 tons x 4 sets, 3 tons every half hour, for a total of 12 tons).

[0058] 5. Before the shutdown, the [Ti] content in the molten iron of the two furnaces was 0.20% and 0.19%, and the [Si] content was 0.16% and 0.18%, respectively; the binary basicity of the slag was 1.08 and 1.04 times, respectively.

[0059] Starting at 6:08, oxygen enrichment was stopped and ventilation and pressure were reduced. The ore batch weight was reduced to 26t (a reduction of 18%), and ventilation was reduced to 2500m.3 / min, when there is a damaged cooling wall, the water pressure in sections 6-10 of the cooling wall is halved, and the airflow is reduced to 1200 m 3 When the flow rate reaches 1 / min, the shutdown is basically over, and the water flow to the damaged cooling wall is cut off.

[0060] II. Re-ventilation Operation 1. After the blast furnace is shut down, the diameter of the three tuyeres, No. 5, No. 13, and No. 15, will be reduced and adjusted to refractory rings with a diameter of 110mm.

[0061] At 2:19:46 (i.e., 10 hours after the blast furnace shutdown), the blast furnace was restarted. After the blast furnace was blasted, the air pressure was controlled to be ≤0.1Mpa, the ore batch weight was 26.0t, and the coke load was 4.00t / t.

[0062] At 3:20:30, the Nantiekou was opened, and the iron sample analysis showed [Ti] 0.15% and [Si] 0.18%.

[0063] 4.20:34 Air volume 1160m³ 3 / min, wind pressure 69KPa (below 0.1MPa), material moving, north foot 1.86m, south foot 2.16m, east foot 2.54m.

[0064] 5.20:56 Air volume 1320m³ 3 / min, wind pressure 79Kpa (below 0.1MPa), first batch of fabric, north foot 2.74m, south foot 2.55m, east foot 3.03m.

[0065] 6. At 21:35, the air volume was increased to 1680m³ / h. 3 / min, pressure difference 101Kpa (lower than 0.11MPa), the material production line is running normally.

[0066] 7.23:50 Air volume increased to 2400m³ 3 / min, pressure difference 109KPa (pressure difference less than 0.12MPa for the first 30 batches), air temperature 1090℃, air pressure rises, minimum air temperature drops to 900℃ (removal air temperature 190℃).

[0067] 8. Increase the air volume to 2450m³ / h (1:22 ratio). 3 / min (restored to 80% of normal air volume), air pressure 210KPa, air permeability 2126, oxygen enrichment 1200Nm 3 / h.

[0068] 9. At 4:30, the air volume was increased to 2880 m³ / h. 3 / min, wind pressure 272KPa, wind temperature 1170℃, oxygen enrichment 7000Nm 3 / h. Furnace temperature rises, iron sample analysis: [Ti] 0.35%, [Si] 0.40%. 4:40 Modified feedstock enters the fourth ring; feedstock composition is shown in the table below:

[0069] 10. 5:30 Air volume 3160m³ 3 / min, wind pressure 299KPa, oxygen enrichment 9600Nm 3 / h, the batch weight increased to 31.0t, and the coke load was 4.50t / t, basically returning to normal.

[0070] As can be seen from the above embodiments, after adopting the high-titanium slag blast furnace shutdown recovery method provided in this disclosure, the blast furnace shutdown process takes only 9 hours and 45 minutes after 10 hours of shutdown. The whole process is stable, the blasting process is not repeated, and production can be quickly and stably restored.

[0071] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0072] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A method for restoring a high-titanium slag blast furnace after a shutdown, characterized in that, Before ceasing wind operations, follow these steps: The coke load is reduced by 13% to 18% starting 4 to 5 hours before the shutdown. 3-4 hours before the shutdown, add clean coke and adjust the material distribution system to: 3-ring ore material system, the width of the ore platform in the radial angle range of 3°~4°, the outer coke-ore angle difference range of 1.5°~2°, and the inner coke-ore angle difference range of 5.5°~6°. One to two hours before shutting down the furnace, the pig iron [Ti] content should be controlled within the range of 0.15% to 0.20%, and the slag binary basicity should be controlled within the range of 1.04 to 1.08 times.

2. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 1, characterized in that, When adding clean coke, if the blast furnace volume is ≤1500 m³ 3 Then add one set of clean coke every 25-35 minutes, for a total of 4-5 sets, until the total amount of clean coke added reaches 12t-15t; if 1500 m 3 Blast furnace volume ≤ 2000 m³ 3 Then, add one set of clean coke every 5 to 7 batches of material, for a total of 4 to 5 sets of clean coke, until the total amount of clean coke added reaches 43t to 50t.

3. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 1, characterized in that, The method for restoring a high-titanium slag blast furnace after a shutdown also includes the following shutdown steps: When the iron tapping process begins and the tapping process is interrupted, oxygen enrichment is stopped and the air pressure is reduced. At the same time, the ore batch weight is reduced by 12% to 18% from the normal level.

4. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 3, characterized in that, The ventilation cessation process also includes: If there are damaged cooling walls, reduce water flow until the shutdown process is complete.

5. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 3, characterized in that, The method for restoring a blast furnace after a shutdown, as described above, also includes: After the ventilation shutdown process is completed, reduce the diameter of the air vent rings of 2-3 air vents by 1 / 12 to 3 / 14.

6. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 1, characterized in that, The method for restoring a high-titanium slag blast furnace after a shutdown also includes the following initial restart steps: Before material movement, control the air pressure to not exceed 0.1 MPa and prohibit feeding. After the material is moved, maintain the furnace top temperature at 250℃~300℃ and start feeding. Control the air pressure to not exceed 0.11MPa, and organize the tapping of iron in front of the furnace.

7. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 6, characterized in that, In the initial re-airing step, if the furnace top temperature exceeds 350℃~400℃ before the material moves, water is sprayed on the furnace top to reduce the furnace top temperature.

8. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 6, characterized in that, The method for restoring a high-titanium slag blast furnace after a shutdown also includes the following post-shutdown restart steps: Once the feed line is operating normally, the material feeding is continuous and uniform, and the furnace top temperature is stable, begin increasing the air supply, with each increase not exceeding 50m³. 3 / min, the air pressure rise should not exceed 5kPa; before feeding 30-35 batches of air, the difference between the hot air pressure and the furnace top pressure should not exceed 0.12MPa. After feeding 30-35 batches, the coke load should be gradually restored to normal according to the furnace temperature. When the air volume is increased to 80% of the normal air volume, the normal material system should be restored and oxygen enrichment should be started. The ore batch weight should be gradually restored from the recovery ore batch weight during the shutdown to the normal ore batch weight according to the air volume.

9. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 8, characterized in that, In the later re-airing step, if the air pressure rises above a predetermined value before 30 to 35 batches of air are supplied and the air temperature is withdrawn by 100°C to 200°C.

10. The method for restoring a high-titanium slag blast furnace after a shutdown according to claim 5, characterized in that, After the air volume is increased to 80% of the normal air volume, if the ratio of air volume to air pressure is less than the predetermined ratio, the air vent ring of one of the 2 to 3 air vents whose diameter has been reduced by 1 / 12 to 3 / 14 will be restored to the diameter before the air vent was shut down, and the air vent area will be increased.

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