Blowing-in method of blast furnace with thin-wall lining

Abstract

The invention discloses a blowing-in method of a thin-wall lining blast furnace, which comprises the following steps: in a clearing and digging process, placing an excavator in the center of a hearth, and carrying out annular clearing and digging by taking the center as a circle center so as to dig out a spraying rebound material and a covering agent from the thin-wall lining blast furnace; in the charging process, first net coke is charged into a first space from a hearth to a bosh, second net coke is charged into a second space from a bosh to a first position of a furnace body, and first empty coke is charged into a third space from the first position of the furnace body to a second position of the furnace body; second empty coke is filled in a fourth space from the second position of the furnace body to the third position of the furnace body, and normal material and third net coke are filled in a fifth space from the third position of the furnace body to the lower edge of the furnace throat. Only the space around the excavator in the hearth is excavated, and the clean coke is filled in the hearth, so that the heat generated by combustion of the clean coke can be utilized to melt the spraying rebound material and the covering agent which are not cleaned below the excavator, smooth blow-in is not influenced, and the blow-in time is shortened.

Description

Technical Field

[0001] The present application belongs to the technical field of steel smelting, and in particular relates to a method for opening a thin-walled lining blast furnace. Background Art

[0002] After a few years of operation, a thin-walled lining blast furnace will be repaired by spraying technology. After the furnace is shut down, the entire blast furnace is sprayed from bottom to top, and then the furnace is restarted. The main purpose of the shutdown is to spray the lining and repair the blast furnace. Unlike overhaul or new construction of a blast furnace, the hearth brickwork is not processed, and only the furnace wall above the tuyere belt combination bricks is sprayed. After the spraying is completed, the thin-walled lining blast furnace needs to be opened.

[0003] The current furnace opening technology requires the overall clearing of the furnace bottom during the excavation stage, and the three-stage charging method is used during the loading stage, which is time-consuming, difficult to control the furnace temperature, and not conducive to controlling the smelting rhythm. Therefore, there is an urgent need for a furnace opening method for thin-walled lined blast furnaces to ensure that thin-walled lined blast furnaces can be opened quickly and smoothly. Summary of the invention

[0004] The embodiments of the present application provide a method for starting a thin-walled lining blast furnace, thereby ensuring rapid and smooth starting of the thin-walled lining blast furnace at least to a certain extent.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0006] According to a first aspect of an embodiment of the present application, a method for opening a thin-walled lined blast furnace after spraying is provided. The thin-walled lined blast furnace includes a furnace hearth, a furnace belly, a furnace waist, a furnace body and a furnace throat from bottom to top. The method includes: during the excavation process, placing an excavator at the center of the furnace hearth, and performing circular excavation with the center as the center of a circle to dig out the sprayed rebound material and the covering agent from the thin-walled lined blast furnace; during the charging process, loading a first clean coke into a first space from the furnace hearth to the furnace belly, loading a second clean coke into a second space from the furnace waist to a first position of the furnace body, and charging a second clean coke into a second space from the first position of the furnace body to a second position of the furnace body. The first empty coke is loaded into the third space of the furnace body, the second empty coke is loaded into the fourth space from the second position of the furnace body to the third position of the furnace body, and the normal material and the third clean coke are loaded into the fifth space from the third position of the furnace body to below the lower edge of the furnace throat; wherein, the first clean coke, the second clean coke and the third clean coke all include coke, and the amount of coke decreases successively, the first empty coke includes coke, fluorite and dolomite, the second empty coke includes coke, fluorite, dolomite, sintered ore and silica, the normal material includes coke, fluorite, dolomite, sintered ore, silica and pelletized ore, and the first position, the second position and the third position increase successively.

[0007] In some embodiments, the first position of the furnace body is at a position 1 meter below the lower edge of the furnace body, the second position of the furnace body is at a position from 1 meter to 2 meters below the lower edge of the furnace body, the third position of the furnace body is at a position from 2 meters to 4 meters below the lower edge of the furnace body, and the fifth space is a space formed at a position 4 meters below the lower edge of the furnace body to 2 meters to 3 meters below the stock line; wherein, the stock line is located inside the furnace throat.

[0008] In some embodiments, normal burden and the third net coke are charged into the fifth space from the third position of the furnace body to below the lower edge of the furnace throat, including:

[0009] The third net coke and normal burden are charged into the fifth space from the third position of the furnace body to below the lower edge of the furnace throat in batches and in sequence, wherein the quantity of the third net coke charged in each batch decreases.

[0010] In some embodiments, the method for starting up a thin-wall lined blast furnace further includes:

[0011] During the furnace drying process, air is blown into the thin-wall lined blast furnace, and the air volume of the blown air is controlled to increase from 1 / 4 of the preset normal air volume to 1 / 3 and then decrease to 1 / 4 of the preset normal air volume;

[0012] Two top gas relief valves are alternately opened every first preset time period;

[0013] The top temperature is controlled to be less than or equal to 300 °C by reducing the air volume or the air temperature;

[0014] When the humidity inside the thin-wall lined blast furnace remains less than or equal to the atmospheric humidity for a second preset time period, the furnace drying ends; wherein, the first preset time period is greater than the second preset time period.

[0015] In some embodiments, the thin-wall lined blast furnace further includes tuyeres and tapholes provided in the hearth, and the method further includes:

[0016] During the process of starting up by blowing air and igniting, air is blown into the thin-wall lined blast furnace through the tuyeres, and the air volume of the blown air is controlled to be 900 m 3 / min to 1000 m 3 / min, and the air temperature is 780 °C to 800 °C;

[0017] The air addition operation is controlled according to a preset air addition operation process control table;

[0018] After all the tuyeres through which air is blown become bright, the air volume control, coal injection, oxygen enrichment, and tapping operations are carried out.

[0019] In some embodiments, the preset air addition operation process control table includes the corresponding air blowing time, the number of tuyeres, and the air volume. Carrying out the air addition operation according to the preset air addition operation process control table includes:

[0020] Opening the tuyeres according to the air blowing time and the number of tuyeres;

[0021] After the tuyere is opened for the third preset duration, blast addition operation is performed according to the blast volume corresponding to the number of tuyeres.

[0022] In some embodiments, when the blast volume in the preset blast addition operation process control table is less than 80% of the preset normal blast volume, the increase amplitude of the blast volume is less than or equal to 200 m 3 / min / time; when the blast volume in the preset blast addition operation process control table is greater than 80% of the preset normal blast volume, the increase amplitude of the blast volume is less than or equal to 100 m 3 / min / time.

[0023] In some embodiments, after all the tuyeres for air supply become bright, air control, coal injection, oxygen enrichment, and tapping operations are performed, including:

[0024] Starting from when all the tuyeres for air supply become bright and after the fourth preset duration, determine the pressure difference between the blast pressure and the top pressure in the thin-walled inner-lined blast furnace or the increase amplitude of the gas utilization rate;

[0025] When the increase amplitude is greater than the preset amplitude, perform blast reduction operation.

[0026] In some embodiments, after all the tuyeres for air supply become bright, air control, coal injection, oxygen enrichment, and tapping operations are performed, including:

[0027] Starting from when all the tuyeres for air supply become bright and after the fifth preset duration, when the top temperature is greater than or equal to 60 °C and the top gas pressure reaches 5 kPa, perform a gas explosion test;

[0028] After the gas explosion test is qualified, introduce gas into the dust removal system and the gas pipeline network;

[0029] When the blast volume in the thin-walled inner-lined blast furnace reaches 80% of the preset normal blast volume and the blast temperature reaches 900 °C, start the coal injection operation;

[0030] When the coal ratio is greater than or equal to 60 kg / t, start the oxygen enrichment operation.

[0031] In some embodiments, after all the tuyeres for air supply become bright, air control, coal injection, oxygen enrichment, and tapping operations are performed, including:

[0032] Starting from when all the tuyeres for air supply become bright and after the sixth preset duration, open the taphole of the first heat;

[0033] When the blast volume in the thin-walled inner-lined blast furnace reaches 70% of the preset normal blast volume, open another taphole and control the alternate tapping of the other taphole and the taphole of the first heat.

[0034] In this application, during the cleaning process, the excavator is placed at the center of the hearth, and circular cleaning is carried out with the center as the center of the circle to dig out the sprayed rebound material and covering agent from the thin-wall lined blast furnace; during the furnace charging process, the first net coke is charged into the first space from the hearth to the belly, the second net coke is charged into the second space from the furnace waist to the first position of the furnace body, the first empty coke is charged into the third space from the first position of the furnace body to the second position of the furnace body, the second empty coke is charged into the fourth space from the second position of the furnace body to the third position of the furnace body, and the normal material and the third net coke are charged into the fifth space from the third position of the furnace body to below the lower edge of the throat. By only cleaning the space around the excavator in the hearth and charging net coke into the hearth, the heat generated by the combustion of the net coke can be used to melt the sprayed rebound material and covering agent that have not been cleaned under the excavator, which not only does not affect the smooth start-up of the furnace but also shortens the start-up time.

[0035] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application. Obviously, the accompanying drawings in the following description are only some embodiments of this application, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. In the drawings:

[0037] Figure 1 A flow schematic diagram of the method for starting up a thin-wall lined blast furnace according to some embodiments of this application is shown;

[0038] Figure 2 Shows Figure 1 The detailed schematic diagram of the furnace charging process in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in this application belong to the scope of protection of this application.

[0040] In addition, the described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present application. However, those skilled in the art will realize that the technical solutions of the present application may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the present application.

[0041] The block diagrams shown in the drawings are only functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0042] The flowcharts shown in the drawings are only exemplary illustrations and do not necessarily include all the content and operations / steps, nor do they necessarily need to be executed in the order described. For example, some operations / steps can be decomposed, some operations / steps need to be interspersed or carried out in parallel, and some operations / steps can be combined or partially combined. Therefore, the actual execution order may change according to the actual situation.

[0043] It should also be noted that the terms "first", "second", etc. in the specification, claims, and above-mentioned drawings of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the objects so used can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described.

[0044] To enable those skilled in the art to better understand the present application, the application scenarios involved in the present application will be briefly described first.

[0045] Shougang Changzhi Iron and Steel Co., Ltd. currently has two blast furnaces in operation, namely the No. 8 blast furnace and the No. 9 blast furnace. In 2019, the No. 9 blast furnace was overhauled and transformed into a thin-wall lining furnace type. In 2022, the No. 8 blast furnace was overhauled and transformed into a thin-wall lining furnace type. In 2024, due to the need of the blast furnace condition and according to the overall arrangement of the company, in April, the No. 9 blast furnace was shut down for spraying and then restarted; in May, the No. 8 blast furnace was shut down for spraying and then restarted. The main purpose of these two shutdowns is spraying and lining construction. Different from overhauling or building a new blast furnace, the brick lining of the hearth is not treated, only the furnace wall above the combined bricks in the tuyere zone is sprayed, and the hearth burden surface, spraying rebound material, and covering agent are cleaned, and then the furnace is charged and started up. To ensure a safe, stable, and smooth startup, based on the startup practice experience of the No. 9 blast furnace in 2019 and the No. 8 blast furnace in 2022, a startup method for a thin-wall lining blast furnace was summarized, generalized, and refined, and successful practice was achieved during the startup process of the No. 9 blast furnace and the No. 8 blast furnace in 2024.

[0046] After the spraying operation of the thin-wall lining blast furnace is completed, generally, the steps of excavation, furnace drying, furnace charging, and ignition and air supply for startup are carried out in sequence. In the related technology, during excavation, the whole hearth needs to be excavated downward, which takes a long time. In the embodiment of the present application, during the excavation process, the hearth is excavated in a circular shape, that is, the part of the hearth where the excavator is located (the bottom of the excavator) does not need to be excavated, and a five-stage full-coke design is adopted for furnace charging. The heat generated by the combustion of the net coke is used to melt the spraying rebound material and covering agent that are not cleaned at the bottom of the excavator. The melted liquid can flow out from the iron notch, which not only does not affect the smooth progress of startup but also shortens the startup time.

[0047] Figure 1 A flow schematic diagram of the startup method of a thin-wall lining blast furnace according to some embodiments of the present application is shown. The thin-wall lining blast furnace sequentially includes a hearth, a bosh, a waist, a shaft, and a throat from bottom to top. As Figure 1 shown, the startup method of the thin-wall lining blast furnace may include:

[0048] Step 101, during the excavation process, place the excavator at the center of the hearth and conduct circular excavation with the center as the center of the circle to dig out the spraying rebound material and covering agent from the thin-wall lining blast furnace;

[0049] Step 102, during the furnace charging process, charge the first net coke into the first space from the hearth to the bosh, charge the second net coke into the second space from the bosh to the first position of the furnace shaft, charge the first empty coke into the third space from the first position to the second position of the furnace shaft, charge the second empty coke into the fourth space from the second position to the third position of the furnace shaft, and charge the normal charge and the third net coke into the fifth space from the third position of the furnace shaft to below the lower edge of the throat; wherein, the first net coke, the second net coke, and the third net coke all include coke, and the quantity of coke decreases successively. The first empty coke includes coke, fluorite, and dolomite. The second empty coke includes coke, fluorite, dolomite, sinter, and silica. The normal charge includes coke, fluorite, dolomite, sinter, silica, and pellet. The first position, the second position, and the third position increase successively.

[0050] It can be understood that after the spraying operation of the thin-wall lined blast furnace is completed, it is necessary to use high-pressure water to wash the slag skin on the furnace wall, the adhesives on the furnace wall, etc. That is, during the spraying process, a very small part of the rebounded material falling into the furnace, the covering agent sprayed into the furnace (used to isolate the gas and reduce the temperature), etc. need to be dug out from the inside of the blast furnace to expose the remaining red slag iron and red coke in the hearth below the covering agent layer.

[0051] In the embodiment of the present application, with the center of the hearth as the center of the circle, put the excavator to start digging. The bottom of the excavator remains stationary, and dig downward in the annular space from the parking position to the furnace wall to dig out the rebounded material and the covering agent.

[0052] Figure 2 shows Figure 1 a detailed schematic diagram of the furnace charging process. As Figure 2 shown, the furnace charge adopts a five-section all-coke design: the first net coke, the second net coke, the first empty coke, the second empty coke, the normal charge + the third net coke. In some embodiments, the first position of the furnace shaft is the position 1 meter below the lower edge of the furnace shaft, the second position of the furnace shaft is the position from 1 meter to 2 meters below the lower edge of the furnace shaft, the third position of the furnace shaft is the position from 2 meters to 4 meters below the lower edge of the furnace shaft, and the fifth space is the space formed by the position 4 meters below the lower edge of the furnace shaft to 2 meters to 3 meters below the burden line; wherein, the burden line is located inside the throat.

[0053] It should be noted that due to the circular cleaning in the hearth, a large amount of the first net coke needs to be added in the hearth and the bosh to level the burden surface height and provide sufficient heat to melt the sprayed rebound material and covering agent that are not cleaned under the excavator and heat the hearth; by loading the second net coke into the second space from the bosh to the first position of the shaft, sufficient heat can be supplemented to fully heat the hearth; by loading the first empty coke into the third space from the first position of the shaft to the second position of the shaft, good fluidity of the slag can be maintained during the slag-making process; by loading the second empty coke into the fourth space from the second position of the shaft to the third position of the shaft, it is beneficial to the penetration and smooth outflow of the slag-iron liquid; by loading the normal burden and the third net coke into the fifth space from the third position of the shaft to below the lower edge of the throat, there is more normal burden in the shaft, which is beneficial to the full heating of the metallic burden.

[0054] In some embodiments, the third net coke and the normal burden can be cyclically loaded in batches in sequence into the fifth space from the third position of the shaft to below the lower edge of the throat, wherein the quantity of the third net coke loaded in each batch decreases.

[0055] During the implementation process, 5 batches of the third net coke and 5 batches of the normal burden can be continuously loaded, then 4 batches of the third net coke and 5 batches of the normal burden can be continuously loaded; 3 batches of the third net coke and 5 batches of the normal burden can be continuously loaded; 2 batches of the third net coke and 5 batches of the normal burden can be continuously loaded; 1 batch of the third net coke and 5 batches of the normal burden can be continuously loaded, and then no third net coke is loaded, only 5 batches of the normal burden are loaded.

[0056] Through the burden charging in the above-mentioned stepped load progression manner, the quantity of coke can be gradually reduced, and the temperature in the furnace can be gradually decreased to facilitate the acceleration of the restoration process.

[0057] During the charging process, the charging system can be: CC↓OO↓; the normal burden line is 2.0 m; for the charging α control: the starting net coke starts at 28° of the corresponding angle, and subsequently, according to the burden line depth, the angle is gradually expanded uniformly to C: 37(3)35(3) O: 36(6), where C represents coke and O represents ore. The ore batch for charging is set at 12 tons, and the ore batch is gradually adjusted according to the furnace condition process after the blast is supplied.

[0058] Through the design of the cleaning process and the charging process in the embodiments of the present application, only the space around the excavator in the hearth is cleaned, and the net coke is loaded into the hearth. The heat generated by the combustion of the net coke can be used to melt the sprayed rebound material and covering agent that are not cleaned under the excavator, which not only does not affect the smooth progress of the furnace start-up but also shortens the furnace start-up time.

[0059] In some embodiments, during the oven drying process, air is supplied to the thin-wall lined blast furnace. After controlling the air volume of the supplied air to increase from 1 / 4 of the preset normal air volume to 1 / 3 and then decrease to 1 / 4 of the preset normal air volume, two top gas release valves are alternately opened every first preset time period. The top temperature is controlled to be less than or equal to 300 °C by reducing the air volume or the air temperature. When the humidity inside the thin-wall lined blast furnace remains less than or equal to the atmospheric humidity for a second preset time period, the oven drying ends; where the first preset time period is greater than the second preset time period.

[0060] It can be understood that the purpose of oven drying is to slowly evaporate the moisture of the gunning material and fully heat the wall; during the process of heating the wall, it is necessary to avoid the wall from expanding rapidly and being damaged, so as to improve the overall strength of the wall and extend the service life of the thin-wall lined blast furnace.

[0061] Before oven drying, a air supply device is installed for the thin-wall lined blast furnace, and the operation conditions of the main body equipment, the feeding system, the burden distribution system, the cooling system, the air supply system, the injection system and the dust removal system are comprehensively inspected. After the commissioning test runs normally, the hot blast stove supplies air to the furnace for oven drying through the air supply device. Return for reference Figure 2 , a plurality of tuyeres are arranged in the hearth part, and a temporary thermocouple can be installed in the air duct of one of the tuyeres to detect the air supply temperature, so as to implement the formulated oven drying plan.

[0062] After air supply, oven drying is carried out according to the pre-formulated spraying oven drying schedule. The heating-up and constant temperature processes are strictly controlled according to the spraying oven drying schedule. It is a heating-up process controlled by taking the air temperature rise as the main line, using the air volume regulation as the means, and being restricted by the top temperature, and regulating according to the oven drying parameters. The oven drying temperature setting is related to the material of the gunning material, and the time setting is related to the spraying thickness.

[0063] In the implementation process, the preset normal air volume can be 3200 m 3 / min, and the air volume of the supplied air can gradually increase from 800 m 3 / min to about 1000 3 / min, and then decrease to 800 3 / min. Two top gas release valves are alternately opened every 8 hours, first opened and then closed to make the temperature rise uniform. During oven drying, the top temperature is controlled below 300 °C. If the top temperature exceeds 300 °C, the air volume or the air temperature is appropriately reduced.

[0064] Since the humidity inside the blast furnace with a thin-wall lining is difficult to directly detect, the humidity of the top gas of the blast furnace with a thin-wall lining can be used as the humidity inside the blast furnace. Exemplarily, when it is detected that the humidity of the top gas is less than or equal to the atmospheric humidity for 4 consecutive hours, the blast is stopped, the furnace is put on standby, and the furnace drying is stopped. After stopping the furnace drying, preparations for charging the furnace are made. There is no designed cooling stage in the furnace drying in the embodiments of the present application, which is different from the furnace drying of traditional major repairs and newly built blast furnaces. This is because the brick linings of traditional major repairs and newly built blast furnaces have a large amount of moisture, and the furnace walls, hearths, and taphole bottoms all need to be baked, requiring a relatively high temperature and a long time. When the furnace drying temperature is high, it is easy to ignite the charged coke, so a cooling stage is designed. However, the present application is for the case of spraying and lining the blast furnace. The moisture content of the sprayed rebound material is less, and the sprayed lining is relatively thin. The furnace drying operation only needs to bake the furnace wall, and the required temperature is not high, so there is no need to design a cooling stage, shortening the furnace drying time.

[0065] As described above, starting up the furnace needs to go through several steps such as cleaning and excavation, furnace drying, charging the furnace, and igniting the blast to start up the furnace. Before igniting the blast to start up the furnace, the blast regime can also be selected.

[0066] During implementation, the tuyere length can be designed to be 450 mm; the tuyere bevel angle is 5°, and there are 20 tuyeres in total. Among them, 11 tuyeres have a diameter of 115 mm, and the other 9 tuyeres have a diameter of 120 mm. The total air inlet area is 0.2159 m 2 .

[0067] When starting up the furnace and igniting, the tuyeres above the two tapholes are fully opened, and 8 tuyeres are blocked. The blast volume for igniting the blast is 1000 m 3 / min, the area of the tuyere is 0.1310 m 2 , and the standard wind speed is 127 m / s. (The opened tuyeres are No. 1, 2, 3, 12, 13, 14, 15, 16, 17, 18, 19, 20, and the blocked tuyeres are No. 4, 5, 6, 7, 8, 9, 10, 11). The blocked tuyeres must be blocked tightly. Use wet gunite plus 5% castable, and then add 1 - 2 bricks to ensure that they cannot be blown open and can be poked open with a steel rod. The south taphole is the main taphole for tapping iron.

[0068] The blast volume for igniting the blast is 1000 m 3 / min, the blast pressure is 100 kPa, the blast temperature is not lower than 800 °C, and then the blast temperature is controlled according to the progress of the furnace condition.

[0069] After the blast is sent, wait until the relationship between the blast pressure and the blast volume is stable, the differential pressure is appropriate and stable, the top temperature of the furnace > 60 °C, and the gas composition is normal, where H2 < 6% and O2 < 0.8%, then the gas can be introduced into the dust removal system and the gas pipeline network.

[0070] After selecting the air supply system, it is also possible to contact the main blast furnace unit (position) and the affiliated units (positions) serving the blast furnace to conduct joint commissioning of their respective areas, sign on the furnace start-up confirmation form after meeting the conditions. After all the above units (positions) have signed, the air supply and ignition furnace start-up operation is carried out.

[0071] In some embodiments, the thin-walled lining blast furnace further includes tuyeres and tapholes provided in the hearth. During the air supply and ignition furnace start-up process, air is supplied into the thin-walled lining blast furnace through the tuyeres, and the air volume of the air supply is controlled to be 900 m 3 / min to 1000 m 3 / min, and the air temperature is 780 °C to 800 °C; the air addition operation is controlled according to a preset air addition operation process control table; after all the tuyeres for air supply become bright, the air control, coal injection, oxygen enrichment, and tapping operations are carried out.

[0072] It can be understood that the air control includes air addition and air reduction, and these operations such as air addition, air reduction, coal injection, oxygen enrichment, and tapping operations can be carried out in parallel or alternately.

[0073] During the air supply and ignition furnace start-up process, after checking and confirming that the states of each valve are correct, the blower sends the blast air to the blast control valve, controls the air volume according to an air supply ratio of about 0.9, and the initial air volume is 900 m 3 / min to 1000 m 3 / min; the air temperature is ensured to be between 780 °C and 800 °C to enable the ignition of coke; check the working conditions of the air supply device and the cooling equipment; observe the working conditions of the tuyeres. After all the tuyeres for air supply are burning brightly, the air addition operation can be carried out, and the air temperature can be adjusted to the required level; check the working conditions of the taphole oxygen lance to prevent the oxygen lance from having poor sealing or being burned out due to excessive temperature, and strictly implement the "Oxygen Lance Furnace Start-up Operation Plan"; after 1 hour when all the tuyeres for air supply are bright, if the furnace top temperature ≥ 60 °C and the furnace top gas pressure reaches 5 kPa, a gas explosion test can be carried out. After passing the test, introduce the gas into the dust removal system and the gas pipeline network according to the procedure. Contact and confirm that the molten iron ladle is in place. Generally, after 10 to 12 hours of air supply, the theoretical amount of iron in the hearth reaches 50 tons, and the first tap of iron is made; add air and open tuyeres according to the actual furnace conditions.

[0074] In some embodiments, the preset air addition operation process control table includes the corresponding air supply time, number of tuyeres, and air volume one by one, and the tuyeres can be controlled to be opened according to the air supply time and the number of tuyeres; the air addition operation is carried out according to the air volume corresponding to the number of tuyeres after the third preset time period from the opening of the tuyeres.

[0075] It can be understood that the air addition operation is carried out when the air volume and air pressure trends are stable, the pressure difference is appropriate, and the burden line trend is smooth. The air volume is not increased within 0.5 hours after opening the tuyeres to ensure that the slag and iron in front of the tuyeres can be digested in time after opening the tuyeres. The air volume is matched with the tuyeres to keep the wind speed meeting the requirements.

[0076] In some embodiments, when the air volume in the preset air addition operation process control table is less than 80% of the preset normal air volume, the increase amplitude of the air volume is less than or equal to 200 m 3 / min / time; when the air volume in the preset air addition operation process control table is greater than 80% of the preset normal air volume, the increase amplitude of the air volume is less than or equal to 100 m 3 / min / time.

[0077] During the process of opening the tuyere, the following precautions should also be noted: (1) The furnace temperature is sufficient, the silicon content and physical heat both meet the standard requirements, and the slag and iron fluidity is good; (2) The burden line trend is good, the slope is basically normal, the burden column has good permeability, the pressure-volume relationship is matched, and the pressure difference is appropriate; (3) The tuyeres adjacent to the tuyere planned to be opened work normally, the water temperature difference is basically close to that of other opened tuyeres, and there is no slag hanging, no burrs, and no raw drop; (4) The external iron notch of the furnace works normally and the slag and iron are discharged smoothly; (5) When the water temperature difference of the planned tuyere to be opened rises significantly, it should be opened in time; (6) The tuyere opening time should be selected after the iron and slag are discharged.

[0078] The first tuyere is opened on the premise of meeting the tuyere opening conditions, which is expected to be carried out 12 hours after the air supply. The second tuyere takes more than 4 hours of stable operation as a cycle. When the tuyere opening conditions are met, the tuyeres are opened in sequence during the process of discharging slag and iron (the tuyere opening interval is 4 hours). After the number of opened tuyeres reaches 80% of the total number of tuyeres, the tuyere opening interval is 12 hours.

[0079] In some embodiments, starting from the time when all the tuyeres for air supply become bright, after the fourth preset time period, the pressure difference between the blast furnace internal pressure and the top pressure or the increase amplitude of the gas utilization rate in the thin-walled lining blast furnace is determined; when the increase amplitude is greater than the preset amplitude, a wind reduction operation is carried out.

[0080] It should be noted that the formation time of the cohesive zone is approximately about 5 hours after all the tuyeres for air supply become bright. During the formation process, the pressure difference between the blast furnace internal pressure and the top pressure in the thin-walled lining blast furnace increases, and the gas utilization rate increases. If the increase amplitude is too obvious and exceeds the control standard, the wind can be actively reduced to control, reduce the pressure difference, smoothly transition the influence of the cohesive zone formation, provide guarantee for the normal recovery of the subsequent smelting process, and save time.

[0081] In some embodiments, starting from the time when all the tuyeres for air supply become bright, after the fifth preset time period, when the top temperature is greater than or equal to 60 °C and the top gas pressure reaches 5 kPa, a gas explosion test is carried out; after the gas explosion test is qualified, gas is introduced into the dust removal system and the gas pipeline network; when the air volume in the thin-walled lining blast furnace reaches 80% of the preset normal air volume and the air temperature reaches 900 °C, the coal injection operation is started; when the coal ratio is greater than or equal to 60 kg / t, the oxygen enrichment operation is started.

[0082] In some embodiments, before coal injection, the load adjustment cycle ≥ 6 hours; after coal injection, the load adjustment cycle ≥ 3 hours; the absolute value of the load ≥ 4.0, and the adjustment amplitude each time ≤ 0.1 until the normal production level is restored.

[0083] During the process of starting the furnace with blast ignition, the ore batch should be gradually increased as the blast volume increases, and it is necessary to ensure that the ore batch and the blast volume correspond and match each other.

[0084] On the first day of starting the furnace, cast iron is smelted; on the second day, No. 10 pig iron is smelted; on the third day, No. 07 pig iron is smelted; on the fourth day, the normal furnace temperature control level is restored.

[0085] In some embodiments, starting from the moment when all the tuyeres with blast become bright, after the sixth preset duration, the taphole of the first heat is opened; when the blast volume in the thin-walled lined blast furnace reaches 70% of the preset normal blast volume, another taphole is opened for tapping, and the tapping of the other taphole and the taphole of the first heat is controlled alternately.

[0086] It can be understood that generally after 10 - 12 hours of blast, the theoretical iron amount in the hearth reaches 50 tons, and the first heat of iron is tapped; then single-taphole tapping is organized, and the interval time is controlled at ≤ 30 minutes. When the blast volume is close to 70% of the preset normal blast volume, another taphole is used for tapping. To ensure the normal operation of the main trough, slag trough, iron trough, and skimmer, it can be continuously used twice, and then tapping with two tapholes is organized, and they are alternately used in the normal one-in-use and one-in-reserve mode, and the tapping interval is controlled at ≤ 20 minutes according to normal tapping.

[0087] The following introduces Application Example 1 of the present application:

[0088] The specific process of shutting down, spraying, and starting up a certain BF No. 1 is as follows:

[0089] On April 2, at 04:06, the blast is stopped for furnace shutdown, repair, and spraying;

[0090] On April 8, at 08:00, the annular excavation and various preparatory work before furnace drying are completed;

[0091] On April 8, at 09:40, furnace drying is carried out according to the pre-formulated spraying and furnace drying schedule, and a temporary thermocouple is installed in the No. 14 air pipe to measure the air temperature.

[0092] Furnace drying is carried out according to the spraying and furnace drying schedule shown in Table 1 below:

[0093] Table 1

[0094]

[0095] During this oven drying process, the main line is to increase the air temperature, the means is to control the air volume, and the restriction is the top furnace temperature. The oven drying process is carried out according to Table 1. The oven drying time is related to the thickness of the gunning material. When the cooling stave position is above section 8, the spraying thickness is 120 mm; when it is below, the spraying thickness is 150 mm. The actual oven drying time is 64 hours. The heating-up time and the constant-temperature time are flexibly adjusted to shorten the entire oven drying time. The setting of the oven drying temperature is related to the material of the gunning material, and the overall time control is related to the spraying thickness.

[0096] At 20:30 on April 10, the humidity inside the thin-walled lining blast furnace was measured to be the same as the atmospheric humidity;

[0097] At 02:00 on April 11, the blast was stopped and the oven drying ended.

[0098] At 02:40 on April 11, charging started according to the charging material list shown in Table 2 below. The material surface was measured while charging;

[0099] At 16:30 on April 11, the charging was completed, the material surface was measured, and the material surface was charged to 2.6 meters.

[0100] Table 2

[0101]

[0102] It can be seen from Table 2 that below 1.0 meter from the lower edge of the furnace body of BF No. 1 is the net coke, from 1 meter to 2 meters from the lower edge of the furnace body is the first empty coke, including auxiliary materials such as fluorite and dolomite, from 2 meters to 4 meters from the lower edge of the furnace body is the second empty coke, including silica, fluorite and dolomite. Above 4 meters from the lower edge of the furnace body is the normal charge + the third net coke. The third net coke and the normal charge adopt a stepped burden distribution method: charging in the way of 5+5, 4+5, 3+5, 2+5. The final 1+5 can be used or not according to the actual height position of the material surface.

[0103] At 19:30 on April 11, all relevant positions contacted and confirmed that the commissioning was completed and the blast supply condition was met, and then signed at the duty room.

[0104] At 20:18 on April 11, the blast was supplied, the blast volume was 1000 m 3 / min, the air temperature was 780 °C. At 21:00, some tuyeres became bright, and at 21:15, all tuyeres with blast supply became bright.

[0105] The blast volume increase operation was carried out according to the blast volume increase and tuyere opening process control table shown in Table 3 below:

[0106] Table 3

[0107] Blowing time 0h 12h 24h 36h 48h 60h 72h 84h 96h Number of tuyeres (pcs) 12 13 15 16 17 17 18 18 19 <![CDATA[Air volume (m 3 / min)]]> 1000 1600 1950 2230 2650 2650 2850 3110 3260

[0108] As can be seen from Table 3, the air supply time refers to the start time to the cut-off time of air supply. The number of tuyeres refers to the quantity of air supply tuyeres, that is, the number of opened tuyeres. The air volume is the air volume operation level during the air supply time, and the normal air volume of BF1 resumes to normal in four days. The normal air volume of BF1 is 3200m 3 / min.

[0109] The formation time of the soft melting zone during the BF1 start-up is approximately 5 to 6 hours after all the tuyeres for air supply are lit. During the formation process, the differential pressure inside BF1 increases and the gas utilization rate improves. At 03:20 on April 12th, the air volume was actively reduced by 100m / min to control and reduce the differential pressure level, smoothly transitioning the impact of the soft melting zone formation, providing guarantee for the subsequent normal recovery of the smelting process and saving time.

[0110] After 48 hours of air supply, when the air volume reaches 83% of the normal air volume, coal injection starts, and oxygen enrichment is carried out 19 hours after coal injection.

[0111] The first taphole is opened 11 hours after air supply. 36 hours later, when the air volume reaches 70% of the normal air volume, another taphole is opened for tapping. Then they are used alternately for normal tapping organization.

[0112] The furnace temperature is controlled according to the furnace temperature control table shown in Table 4 below:

[0113] Table 4

[0114] Blowing time First furnace 12h 24h 36h 48h 60h 72h 84h 96h Si content (%) 1.83 2.55 2.22 1.11 0.92 0.98 0.64 0.61 0.47 Physical heat (°C) 1300 1400 1472 1496 1496 1507 1509 1490 1488

[0115] As can be seen from Table 4, the furnace temperature control is relatively high on the first day of start-up for smelting foundry pig iron; on the second day, No. 10 pig iron is smelted; on the third day, the furnace temperature is reduced to smelt No. 07 pig iron, and normal production resumes on the fourth day.

[0116] The control is carried out according to the start-up burden change sheet shown in Table 5 below:

[0117] Table 5

[0118] Blowing time (h) Ore batch (t) Burden Stock line (m) Blasting angle Slag basicity Blast-on 12 2.5 2.5 C: 37(3) 35(3) O: 36(6) 1 12 14 2.8 2.5 C: 37(3) 35(3) O: 36(6) 1 24 17 3 2 C: 38(3) 36(3) O: 37(6) 1 36 20 3 2 C: 38(3) 36(3) O: 37(6) 1.05 48 22 3.5 1.8 C: 41(3) 39(2) 36(2) 32(2) O: 38(4) 37(4) 1.1 60 24 3.7 1.8 C: 41(3) 39(2) 36(2) 32(2) O: 38(4) 37(4) 1.1 72 25 3.9 1.8 C: 41(3) 39(2) 36(2) 32(2) O: 38(4) 37(4) 1.15 84 27 4 1.8 C: 42(3) 40(2) 37(2) 34(2) O: 39(5) 38(5) 1.15 96 28 4.05 1.8 C: 42(3) 40(2) 37(2) 34(2) O: 39(5) 38(5) 1.18

[0119] It takes 4 days for BF1 to restore the air volume to the normal level and the furnace temperature to return to the normal level, successfully achieving a successful start-up and meeting the expected goal.

[0120] The following introduces Application Example 2 of the present application:

[0121] The specific process of the start-up of BF2 after shutdown and spraying is as follows:

[0122] On May 2nd, at 03:15, the blast furnace is shut down for maintenance and spraying.

[0123] On May 5th, at 18:00, all the preparatory work before the circular excavation and furnace baking is completed.

[0124] On May 5th at 19:40, start the furnace drying according to the pre - established spraying furnace drying schedule, and install a temporary thermocouple in the No. 4 air duct to measure the air temperature.

[0125] Start the furnace drying according to the spraying furnace drying schedule shown in Table 6 below:

[0126] Table 6

[0127]

[0128] For this furnace drying, take the air temperature rise as the main line, use the air volume regulation as a means, and take the furnace top temperature as a constraint, and carry out the furnace drying process according to Table 6. The furnace drying time is related to the thickness of the sprayed coating. When the cooling wall position is above section 8, the spraying thickness is 100mm, and below section 8, the spraying thickness is 120mm, and the furnace drying takes 52 hours. Flexibly adjust the heating - up and constant - temperature time to shorten the whole furnace drying time. The setting of the furnace drying temperature is related to the material of the sprayed coating, and the overall time control is related to the spraying thickness.

[0129] On May 7th at 19:30, measure that the humidity inside the thin - walled lining blast furnace is the same as the atmospheric humidity;

[0130] On May 7th at 23:55, stop the blast, and the furnace drying ends.

[0131] On May 8th at 02:40, start charging the furnace according to the charging material list shown in Table 7 below, and measure the material surface while charging;

[0132] On May 11th at 16:30, the charging of the furnace is completed, the measurement of the material surface is completed, and the material surface is charged to 2.1 meters.

[0133] Table 7

[0134]

[0135]

[0136] It can be seen from Table 7 that below 1.0 meter from the lower edge of the furnace body of BF No. 2 is the net coke, from 1 meter to 2 meters below the lower edge of the furnace body is the first section of empty coke, including auxiliary materials such as fluorite and dolomite, from 2 meters to 4 meters below the lower edge of the furnace body is the second section of empty coke, including silica, fluorite and dolomite. Above 4 meters below the lower edge of the furnace body is the normal charge + the third net coke. The third net coke and the normal charge adopt a stepped charging method: charge in the order of 4 + 5, 3 + 5, 2 + 5, 1 + 5. The first net coke in BF No. 2 is 8 batches more than the first net coke in BF No. 1. The reasons are as follows: the volume of the furnace hearth excavation is different, there are differences in their respective furnace type designs, and about 3 batches of coke are required to fill and correct; about 2 batches of coke are burned more due to the ignition of the oxygen lance heating; the material surface difference is 50mm, and about 2 batches of coke are required; about 1 batch is corrected for the difference in coke quality particle size).

[0137] On May 8th at 18:10, relevant positions contact and confirm that the commissioning is completed and the blast - sending condition is met, and then sign and approve at the duty room.

[0138] On May 8, at 19:18, air was blown in with an air volume of 1000 m 3 / min and an air temperature of 800 °C. At 19:38, some tuyeres became bright, and by 20:15, all tuyeres through which air was being blown had become bright.

[0139] The air addition operation was carried out according to the air addition and tuyere opening process control table shown in Table 8 below:

[0140] Table 8

[0141] Blowing time 0h 12h 24h 36h 48h 60h 72h 84h 96h Number of tuyeres (pcs) 12 12 14 15 16 17 18 18 19 <![CDATA[Air volume (m 3 / min)]]> 1000 1500 1800 2120 2300 2550 2700 2850 3030

[0142] As can be seen from Table 8, the air blowing time refers to the start time to the cut-off time of air blowing. The number of tuyeres refers to the number of tuyeres through which air is being blown, that is, the number of opened tuyeres; the air volume is the air volume operation level at the air blowing time. The normal air volume was restored in four days, and the normal air volume of BF 2 was 3000 m 3 / min.

[0143] The formation time of the softening-melting zone during the start-up of BF 2 was approximately 5 - 6 hours after all tuyeres through which air was being blown became bright. During the formation process, the differential pressure inside BF 2 increased and the gas utilization rate improved. At 00:20 on May 9, the air volume was actively reduced by 300 m / min to control and reduce the differential pressure level, smoothly transitioning the impact of the formation of the softening-melting zone, providing guarantee for the normal recovery of the subsequent smelting process and saving time. (The larger reduction in air volume of BF 2 compared to BF 1 is related to the higher burden surface of BF 2 compared to BF 1)

[0144] After blowing air for 56 hours, when the air volume reached 80% of the normal air volume, coal injection started, and oxygen enrichment was carried out 26 hours after coal injection.

[0145] The first taphole was opened 12 hours after blowing air. After 30 hours, when the air volume reached 70% of the normal air volume, another taphole was opened for tapping. Then they were used alternately for normal tapping organization.

[0146] The furnace temperature was controlled according to the furnace temperature control table shown in Table 9 below:

[0147] Table 9

[0148] Blowing time First furnace 12h 24h 36h 48h 60h 72h 84h 96h Si content (%) 3.85 3.18 2.18 1.20 0.91 0.93 0.70 0.61 0.47 Physical heat (°C) 1310 1340 1485 1492 1506 1503 1474 1485 1493

[0149] As can be seen from Table 9, the furnace temperature was controlled at a relatively high level on the first day of start-up for smelting foundry pig iron; on the second day, No. 10 pig iron was smelted; on the third day, the furnace temperature was reduced to smelt No. 07 pig iron, and normal production was restored on the fourth day.

[0150] The control was carried out according to the start-up burden change list shown in Table 10 below:

[0151] Table 10

[0152] Time (h) Ore batch (t) Burden Stock line (m) Blasting angle Slag basicity Blast-on 12 2.5 2 C 27(3) 25(3) O 26(6) 0.9 12 12 2.7 2 C 27(3) 25(3) O 26(6) 1.05 24 14 2.8 1.6 C 29(3) 27(2) 24(2) O 27(6) 1.05 36 17 3 1.5 C 29(3) 27(2) 24(2) O 27(6) 1.1 48 21 3.5 1.5 C 30(3) 28(2) 26(2) 23(2) O 27.5(5) 26.5(3) 1.1 60 25 3.5 1.5 C 30(3) 28(2) 26(2) 23(2) O 27.5(5) 26.5(3) 1.15 72 26.6 3.8 1.5 C 30(3) 28(2) 26(2) 23(2) O 28(4) 27(5) 1.15 84 28.6 3.9 1.5 C 30(3) 28(2) 26(2) 23(2) O 28(4) 27(5) 1.15 96 29.6 4 1.5 C 30(3) 28(2) 26(2) 23(2) O 28(4) 27(5) 1.18

[0153] It took 4 days for the blast furnace 2 to restore the air volume to the normal level and the furnace temperature to return to the normal level, successfully achieving the successful furnace start-up and meeting the expected goals.

[0154] The above are only the embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for starting up a blast furnace with a thin-walled inner lining, characterized in that, The thin-walled lined blast furnace successively includes a hearth, a bosh, a waist, a shaft and a throat from bottom to top, and the method includes: During the cleaning process, place an excavator at the center of the hearth and perform circular cleaning with the center as the center of the circle to dig out the sprayed rebound material and covering agent from the thin-walled lined blast furnace. During the furnace charging process, charge the first net coke into the first space from the hearth to the bosh, charge the second net coke into the second space from the waist to the first position of the shaft, charge the first empty coke into the third space from the first position to the second position of the shaft, charge the second empty coke into the fourth space from the second position to the third position of the shaft, and charge the normal charge and the third net coke into the fifth space from the third position of the shaft to below the lower edge of the throat; wherein, the first net coke, the second net coke and the third net coke all include coke, and the quantity of coke decreases successively, the first empty coke includes coke, fluorite and dolomite, the second empty coke includes coke, fluorite, dolomite, sinter and silica, the normal charge includes coke, fluorite, dolomite, sinter, silica and pellets, and the first position, the second position and the third position increase successively.

2. The method for starting up a blast furnace with a thin-walled inner lining according to claim 1, characterized in that The first position of the shaft is the position 1 meter below the lower edge of the shaft, the second position of the shaft is the position from 1 meter to 2 meters below the lower edge of the shaft, the third position of the shaft is the position from 2 meters to 4 meters below the lower edge of the shaft, and the fifth space is the space formed by the position 4 meters below the lower edge of the shaft to 2 meters to 3 meters below the stock line; wherein, the stock line is located in the throat.

3. The method for starting up a blast furnace with a thin-walled inner lining according to claim 2, characterized in that, The charging of the normal charge and the third net coke into the fifth space from the third position of the shaft to below the lower edge of the throat includes: Sequentially charge the third net coke and the normal charge into the fifth space from the third position of the shaft to below the lower edge of the throat in batches and in a cycle, wherein the quantity of the third net coke charged in each batch decreases.

4. The method for starting up a blast furnace with a thin-walled inner lining according to claim 1, characterized in that, It also includes: During the stove drying process, supply air to the thin-walled lined blast furnace, control the air volume of the supplied air to increase from 1 / 4 of the preset normal air volume to 1 / 3, and then decrease to 1 / 4 of the preset normal air volume. Open two top gas relief valves alternately every first preset time period. Control the top temperature to be less than or equal to 300 °C by reducing the air volume or the air temperature. End the stove drying when the humidity in the thin-walled lined blast furnace is less than or equal to the atmospheric humidity for a second preset time period; wherein, the first preset time period is greater than the second preset time period.

5. The method for starting up a blast furnace with a thin-walled inner lining according to claim 1, characterized in that, The thin-walled lined blast furnace further includes tuyeres and tapholes arranged on the hearth, and the method further includes: During the process of starting the furnace by blowing air for ignition, air is blown into the thin-walled lined blast furnace through the tuyere, and the air volume of the blown air is controlled to be 900 m 3 / min to 1000 m 3 / min, and the air temperature is 780 °C to 800 °C; Perform the air addition operation according to the preset air addition operation process control table. After all the tuyeres for supplying air become bright, perform the air control, coal injection, oxygen enrichment and tapping operations.

6. The method for starting up a blast furnace with a thin-walled inner lining according to claim 5, characterized in that, The preset air addition operation process control table includes the corresponding air supply time, the number of tuyeres and the air volume one by one. The performing of the air addition operation according to the preset air addition operation process control table includes: Control the opening of the tuyeres according to the air supply time and the number of tuyeres. Perform the air addition operation according to the air volume corresponding to the number of tuyeres after the tuyeres are opened for a third preset time period.

7. The method for starting up a blast furnace with a thin-walled inner lining according to claim 6, characterized in that, When the air volume in the preset air addition operation process control table is less than 80% of the preset normal air volume, the increase amplitude of the air volume is less than or equal to 200 m 3 / min / time; when the air volume in the preset air addition operation process control table is greater than 80% of the preset normal air volume, the increase amplitude of the air volume is less than or equal to 100 m 3 / min / time.

8. The method for starting up a blast furnace with a thin-walled inner lining according to claim 5, characterized in that After all the tuyeres for air supply become bright, control the air flow, inject coal, enrich oxygen and tap the iron, including: Starting from when all the tuyeres for air supply become bright, after a fourth preset time period, determine the pressure difference between the blast pressure and the top pressure in the thin-wall lined blast furnace or the increase amplitude of the gas utilization rate; In the case where the increase amplitude is greater than the preset amplitude, perform an air flow reduction operation.

9. The method for starting up a blast furnace with a thin-walled inner lining according to claim 5, characterized in that, After all the tuyeres for air supply become bright, control the air flow, inject coal, enrich oxygen and tap the iron, including: Starting from when all the tuyeres for air supply become bright, after a fifth preset time period, when the top temperature is greater than or equal to 60 °C and the top gas pressure reaches 5 kPa, conduct a gas explosion test; After the gas explosion test is qualified, introduce gas into the dust removal system and the gas pipeline network; When the air flow in the thin-wall lined blast furnace reaches 80% of the preset normal air flow and the air temperature reaches 900 °C, start the coal injection operation; In the case where the coal ratio is greater than or equal to 60 kg / t, start the oxygen enrichment operation.

10. The method for starting up a blast furnace with a thin-walled inner lining according to claim 5, characterized in that, After all the tuyeres for air supply become bright, control the air flow, inject coal, enrich oxygen and tap the iron, including: Starting from when all the tuyeres for air supply become bright, after a sixth preset time period, open the taphole of the first heat; When the air flow in the thin-wall lined blast furnace reaches 70% of the preset normal air flow, open another taphole to tap the iron, and control the alternate tapping of the iron from the other taphole and the taphole of the first heat.

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