Rapid recovery method for high-proportion all-vanadium-titanium pellet blast furnace within 4 hours of planned short-term damping down

Abstract

The invention provides a quick recovery method for a high-proportion all-vanadium-titanium pellet blast furnace within 4 hours of planned short-term damping-down. The quick recovery method comprises the following steps: A) controlling a heat system and a slagging system before damping-down; B) controlling net coke, ore batch weight and coke load before damping-down; C) controlling a charging system before damping-down; through combined application of the control means, the recovery time of the high-vanadium-titanium pellets after short-term damping down within 4h is effectively shortened, and the use amount of coke is saved; and the purposes of stable and smooth operation of the blast furnace, efficiency improvement, cost reduction and environment-friendly production are achieved.

Description

Technical Field

[0001] This invention relates to the field of high-titanium vanadium-titanium magnetite smelting technology, and in particular to a rapid recovery method for a blast furnace with a high proportion of all-vanadium-titanium pellets during a planned short-term shutdown of 4 hours. Background Technology

[0002] Blast furnace smelting of high-titanium vanadium-titanium magnetite is a key technology for the comprehensive utilization of vanadium-titanium magnetite resources in my country. The blast furnace smelting process for high-titanium vanadium-titanium magnetite is characterized by low ore grade, low strength, easy pulverization, high blast furnace slag viscosity, poor slag fluidity, and poor slag-iron separation. This results in significant difficulties in iron ore agglomeration and blast furnace operation, high energy consumption in the ironmaking process, and substantial environmental pressure. In recent years, the optimization of ironmaking processes, represented by high-proportion blast furnace pelletizing and belt roasting machine pellet production, has become a hot technological route for low-carbon green production and ultra-low emissions in the ironmaking industry.

[0003] Increasing the proportion of pellets in blast furnaces is key to optimizing the blast furnace ironmaking process. However, this process inevitably faces numerous technical challenges, such as the rapid recovery of the blast furnace after a shutdown. Blast furnace shutdowns are an essential part of blast furnace production, but the recovery process after a shutdown is far more difficult than routine blast furnace operations. If the problem of rapid recovery after a shutdown using high-proportion vanadium-titanium pellets cannot be solved, it will inevitably affect the application of optimized ironmaking processes, such as high-proportion blast furnace pelletizing and belt roaster pellet production, hindering improvements in cost, efficiency, and environmental protection in the ironmaking process.

[0004] In the smelting of high-titanium vanadium-titanium magnetite, vanadium-titanium pellets have disadvantages compared to ordinary pellets, such as lower grade and lower compressive strength. Furthermore, the smelting of high-titanium vanadium-titanium magnetite is characterized by high slag viscosity, easy pulverization of furnace charge, and poor blast furnace permeability. Compared to ordinary ore smelting, the rapid recovery technology for blast furnace shutdowns in high-proportion vanadium-titanium pellet smelting is extremely challenging. There are no similar high-titanium vanadium-titanium magnetite smelting enterprises, either domestically or internationally, to learn from or reference. Therefore, the smelting technology for high-proportion vanadium-titanium pellets requires the exploration and development of rapid recovery methods after blast furnace shutdowns, creating conditions for optimizing the ironmaking process.

[0005] Under traditional low-proportion all-vanadium-titanium pellet smelting conditions, the recovery time for a planned short-term blast furnace shutdown of 4 hours typically ranges from 8 to 16 hours. The longer the shutdown, the longer the recovery time, generally requiring the addition of 30 to 60 tons of coke and a significant reduction in coke load. Faced with the changes in process conditions brought about by high-proportion all-vanadium-titanium pellet smelting, blast furnaces must research and develop a more efficient method for recovering from planned short-term shutdowns to adapt to these changes, ultimately achieving the goals of ensuring stable and smooth blast furnace operation, improving efficiency, reducing costs, and promoting environmentally friendly production. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a rapid recovery method for a blast furnace with a high proportion of vanadium-titanium pellets during a planned short-term shutdown of 4 hours. This recovery method can quickly restore the blast furnace's air supply during a short-term shutdown of 4 hours.

[0007] In view of this, this application provides a rapid recovery method for a blast furnace with a high proportion of vanadium-titanium pellets during a planned short-term shutdown of 4 hours, including: A) control of the thermal regime and slagging regime before shutdown, B) control of net coke, ore batch weight and coke load before shutdown, C) control of the charging regime before shutdown, D) control of the air supply regime before shutdown, and E) air supply recovery method after short-term shutdown.

[0008] The control of the pre-shutdown heating system and slag-forming system includes:

[0009] A1) 8-24 hours before the blast furnace shutdown, the [Ti] content in molten iron should be controlled at 0.13-0.28 wt%, and 0-8 hours before the blast furnace shutdown, the [Ti] content in molten iron should be controlled at 0.15-0.28 wt%.

[0010] A2) The TiO2 content in the slag is controlled at 21.0–23.0 wt%, the binary basicity of the slag is 1.02–1.10, and the ternary basicity of the slag is 1.37–1.47;

[0011] The control of pre-shutdown coke cleaning, ore batch weight, and coke load includes:

[0012] B1) For short-term shutdowns of ≤2 hours, add clean coke separately in 1-2 batches 4-6 hours before the shutdown.

[0013] For short-term ventilation shutdowns of 2-4 hours, add clean coke separately in 2-3 batches 4-6 hours before the shutdown.

[0014] B2) For short-term ventilation shutdowns of ≤2h, the ore batch weight should be reduced by 0-3% and the coke compound weight should be reduced by 0-3% 2-5h before the shutdown.

[0015] For short-term ventilation shutdowns of 2-4 hours, 4-5 hours before the shutdown, the ore batch weight should be reduced by 0-3% and the coke load should be reduced by 0-3% based on the previous values. 2-3 hours before the shutdown, the ore batch weight should be further reduced by 0-3% and the coke load should be further reduced by 0-3% based on the previous values.

[0016] The control of the pre-shutdown loading system, wherein the shutdown time is 2-4 hours, includes:

[0017] C1) The number of rings for ore and coke will be reduced by 1 ring respectively from the previous number of rings;

[0018] C2) The difference between the maximum and minimum ore angles is reduced by 0.5–2.0° from the original value.

[0019] C3) The difference between the maximum angle of coke and the maximum angle of ore in the fabric matrix is ​​1.0 to 2.0°, the difference between the maximum angle of ore and the minimum angle of coke is 6.0 to 8.0°, and the angle difference between adjacent fabric angles of ore and coke is 1.5 to 3.0°.

[0020] C4) The total number of ore rings remains unchanged, while the total number of coke rings is reduced by 1-2 rings compared to the previous adjustment. The number of rings at the middle angle of ore is 1-2 more than the number of rings at the maximum and minimum angles of ore, and the number of rings at the middle angle of coke is 1-3 fewer than the number of rings at the maximum and minimum angles of coke. The number of rings at the maximum and minimum angles of ore and coke is equal. The number of rings for ore and coke at the maximum and minimum feeding angles is 3-5 rings, and the number of rings for ore and coke at other angles is 1-3 rings.

[0021] C5) The minimum fabric feeding angle for coke is controlled at 24.0–30.0°;

[0022] The control of the pre-shutdown air supply system includes:

[0023] D1) The control of air volume and oxygen enrichment should be based on the upper and lower limits of the blast furnace pressure difference being 3-8 kPa lower than the normal production level.

[0024] The method for restoring air supply after a short-term ventilation shutdown includes:

[0025] E1) Before air supply, the blast furnace air inlet area is reduced by 1-12% based on the normal air inlet area;

[0026] E2) Pressure difference control during air volume recovery: When air volume is less than 50% of normal air volume, pressure difference ≤ 0.130 MPa; when air volume is 50-70% of normal air volume, pressure difference ≤ 0.145 MPa; when air volume is 70-90% of normal air volume, pressure difference ≤ 0.165 MPa; when air volume is greater than 90% of normal air volume, pressure difference ≤ 0.175 MPa.

[0027] During the process of restoring road conditions and increasing air volume after the shutdown of E3, the [Ti] content of molten iron is controlled at 0.15-0.28 wt%; the TiO2 content in slag is controlled at 21.0-23.0%; the binary basicity of slag is controlled at 1.02-1.10; and the ternary basicity of slag is controlled at 1.37-1.47.

[0028] In some specific embodiments, the blast furnace charge structure includes: 45-65 wt% vanadium-titanium pellets, with the remainder being vanadium-titanium sinter.

[0029] In some specific embodiments, in step A2), when the TiO2 content in the slag is controlled at the upper limit, the [Ti] content in the molten iron, the binary basicity of the slag, and the ternary basicity of the slag are controlled at the lower limit; when the TiO2 content in the slag is controlled at the lower limit, the [Ti] content in the molten iron, the binary basicity of the slag, and the ternary basicity of the slag are controlled at the upper limit.

[0030] In some specific embodiments, in step B1), for short-term ventilation shutdowns with a shutdown time of ≤2h, the control of coke removal is specifically as follows:

[0031] Four to six hours before shutting down the wind turbine, add clean coke in 1 to 2 batches, with a total amount of clean coke added before shutting down the wind turbine at 4.5 to 12.0 kg / m³. 3 Furnace volume control.

[0032] In some specific embodiments, in step B1), for short-term ventilation shutdowns of 2-4 hours, the control of coke removal is specifically as follows:

[0033] Four to six hours before shutting down the wind turbine, add clean coke in 2 to 3 batches, with a total amount of clean coke added before shutting down the wind turbine at 9.0 to 18.0 kg / m³. 3 Furnace volume control.

[0034] In some specific embodiments, the downtime is less than 2 hours, and the pre-downtime loading system is not adjusted.

[0035] In some specific embodiments, in the method for restoring air supply after a short-term shutdown, if the collapsed material exceeds the material line by more than 3.0m in the early stage of air supply restoration, 2.0-6.0kg / m³ of coke is added separately. 3 Furnace capacity.

[0036] In some specific embodiments, step E3) is followed by:

[0037] During the initial stage of blasting, the hot blast pressure is increased to 0.08–0.12 MPa, while waiting for the furnace charge to descend.

[0038] When the feeding is smooth, the pressure differential is within a suitable range, and there is no collapse or uneven feeding, increase the blast furnace air volume by 50-100 m³ / h each time. 3 / min, with an interval of ≥3min between each increase in air volume;

[0039] When the air volume increases to 50-60% of the normal air volume, gradually increase the furnace top pressure to 0.040 MPa. Increase the furnace top pressure after each air increase, with the pressure increased for every 100 m³ / h increase in air volume. 3 / min, the furnace top pressure is increased by 0.007~0.010MPa accordingly;

[0040] When the air volume increases to more than 50% of the normal level, pulverized coal injection begins;

[0041] When the air volume increases to more than 70% of the normal level, the ore batch weight and coke load begin to be gradually increased. For every 200-300 m³ / h increase in air volume... 3 / min, ore load increases by 1.0 to 2.0 t / batch, coke load increases by 0.10 to 0.20;

[0042] When the air volume reaches more than 90% of the normal level, the ore batch weight and coke load will recover to 95-100% of the normal level.

[0043] When the air volume increases to 75-85% of the normal level, the fabric matrix is ​​adjusted to the normal loading system;

[0044] When the air volume increases to the standard wind speed of 200-260 m / s, remove the refractory mud or refractory ring inside the air outlet sleeve until the air volume returns to the normal level.

[0045] In some specific embodiments, the furnace volume of the blast furnace is 1200–2200 m³. 3 .

[0046] This application provides a method for recovering from a planned short-term shutdown of 4 hours in a blast furnace smelting high-proportion vanadium-titanium pellets. It controls the pre-shutdown thermal regime and slagging regime to improve slag-iron fluidity, ensure complete slag and iron removal, and increase hearth heat reserve, creating conditions for rapid blast furnace recovery after shutdown. Controlling the pre-shutdown net coke, ore batch weight, and coke load improves the permeability of the charge column, loosens the airflow at the edges and center, and further increases the blast furnace heat reserve. This ensures good charge column permeability, reasonable gas flow distribution, and sufficient furnace temperature during blast furnace recovery, facilitating rapid recovery. Furthermore, it regulates the pre-shutdown charging regime, pre-shutdown blasting regime, and post-short-term blasting recovery method in multiple ways, enabling a rapid recovery from a planned short-term shutdown of 4 hours in blast furnace smelting high-proportion vanadium-titanium pellets. This reduces the recovery time by 4-8 hours compared to low-proportion vanadium-titanium pellets shutdown, saving 25-50% of time and 10-30 tons of coke. Detailed Implementation

[0047] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0048] In view of the problem that the recovery time of a blast furnace under the existing technology for a planned short-term shutdown of 4 hours under the condition of low proportion full vanadium-titanium pellet smelting is long and requires the addition of coke, this application provides a rapid recovery method for a blast furnace under the planned short-term shutdown of 4 hours under the condition of high proportion full vanadium-titanium pellet smelting. By adjusting the relevant systems before and after the shutdown, the recovery time after a planned short-term shutdown of 4 hours under the normal production period under the condition of high proportion full vanadium-titanium pellet smelting is shortened by 4 to 8 hours compared with the recovery time after a shutdown of a blast furnace under the same conditions for low proportion full vanadium pellet smelting. This method achieves the purpose of stable blast furnace operation, improved efficiency, reduced costs, and environmentally friendly production. Specifically, the embodiments of this invention disclose a rapid recovery method for a blast furnace under the planned short-term shutdown of 4 hours under the condition of high proportion full vanadium-titanium pellet smelting, including: A) control of the thermal system and slag-making system before shutdown, B) control of the net coke, ore batch weight, and coke load before shutdown, C) control of the charging system before shutdown, D) control of the air supply system before shutdown, and E) air supply recovery method after short-term shutdown.

[0049] The control of the pre-shutdown heating system and slag-forming system includes:

[0050] A1) 8-24 hours before the blast furnace shutdown, the [Ti] content in molten iron should be controlled at 0.13-0.28 wt%, and 0-8 hours before the blast furnace shutdown, the [Ti] content in molten iron should be controlled at 0.15-0.28 wt%.

[0051] A2) The TiO2 content in the slag is controlled at 21.0–23.0 wt%, the binary basicity of the slag is 1.02–1.10, and the ternary basicity of the slag is 1.37–1.47;

[0052] The control of pre-shutdown coke cleaning, ore batch weight, and coke load includes:

[0053] B1) For short-term shutdowns of ≤2 hours, add clean coke separately in 1-2 batches 4-6 hours before the shutdown.

[0054] For short-term ventilation shutdowns of 2-4 hours, add clean coke separately in 2-3 batches 4-6 hours before the shutdown.

[0055] B2) For short-term ventilation shutdowns of ≤2h, the ore batch weight should be reduced by 0-3% and the coke compound weight should be reduced by 0-3% 2-5h before the shutdown.

[0056] For short-term ventilation shutdowns of 2-4 hours, 4-5 hours before the shutdown, the ore batch weight should be reduced by 0-3% and the coke load should be reduced by 0-3% based on the previous values. 2-3 hours before the shutdown, the ore batch weight should be further reduced by 0-3% and the coke load should be further reduced by 0-3% based on the previous values.

[0057] The control of the pre-shutdown loading system, wherein the shutdown time is 2-4 hours, includes:

[0058] C1) The charging system is adjusted from "4-5 ring charging system for ore" to "3-4 ring charging system for ore", and the charging system for coke is also reduced accordingly. That is, after the adjustment of the charging system, the number of rings for ore and coke is reduced by 1 ring respectively from the previous system. For example, the charging system is adjusted from "5 ring charging system for ore" to "4 ring charging system for ore" or from "4 ring charging system for ore" to "3 ring charging system for ore".

[0059] C2) The difference between the maximum and minimum ore angles is reduced by 0.5–2.0° from the original value.

[0060] C3) The difference between the maximum angle of coke and the maximum angle of ore in the fabric matrix is ​​1.0 to 2.0°, the difference between the maximum angle of ore and the minimum angle of coke is 6.0 to 8.0°, and the angle difference between adjacent fabric angles of ore and coke is 1.5 to 3.0°.

[0061] C4) The total number of ore rings remains unchanged, while the total number of coke rings is reduced by 1-2 rings compared to the previous adjustment. The number of rings at the middle angle of ore is 1-2 more than the number of rings at the maximum and minimum angles of ore, and the number of rings at the middle angle of coke is 1-3 fewer than the number of rings at the maximum and minimum angles of coke. The number of rings at the maximum and minimum angles of ore and coke is equal. The number of rings for ore and coke at the maximum and minimum feeding angles is 3-5 rings, and the number of rings for ore and coke at other angles is 1-3 rings.

[0062] C5) The minimum fabric feeding angle for coke is controlled at 24.0–30.0°;

[0063] The control of the pre-shutdown air supply system includes:

[0064] D1) The control of air volume and oxygen enrichment should be based on the upper and lower limits of the blast furnace pressure difference being 3-8 kPa lower than the normal production level.

[0065] The method for restoring air supply after a short-term ventilation shutdown includes:

[0066] E1) Before air supply, the blast furnace air inlet area is reduced by 1-12% based on the normal air inlet area;

[0067] E2) Pressure difference control during air volume recovery: When air volume is less than 50% of normal air volume, pressure difference ≤ 0.130 MPa; when air volume is 50-70% of normal air volume, pressure difference ≤ 0.145 MPa; when air volume is 70-90% of normal air volume, pressure difference ≤ 0.165 MPa; when air volume is greater than 90% of normal air volume, pressure difference ≤ 0.175 MPa.

[0068] During the process of restoring road conditions and increasing air volume after the shutdown of E3, the [Ti] content of molten iron is controlled at 0.15-0.28 wt%; the TiO2 content in slag is controlled at 21.0-23.0%; the binary basicity of slag is controlled at 1.02-1.10; and the ternary basicity of slag is controlled at 1.37-1.47.

[0069] In this application, the rapid recovery method for a blast furnace with a high proportion of vanadium-titanium pellets during a planned short-term shutdown of up to 4 hours is described. The short-term shutdown is specifically defined as within 4 hours, which can be 4 hours, 3 hours, 2 hours, or 1 hour. The recovery method provided in this application is applicable to effective volumes of 1200–2200 m³. 3 The blast furnace; during normal production, the TiO2 content in the blast furnace slag is 21.0-23.0%, and the furnace charge structure includes: 45-65 wt% vanadium-titanium pellets, with the remainder being vanadium-titanium sinter.

[0070] To improve blast furnace recovery efficiency after shutdown, proper control of furnace temperature and slag composition before shutdown aims to improve slag-iron fluidity, ensure complete slag and iron removal, and increase hearth heat reserve, thus creating conditions for rapid blast furnace recovery. This proper control of furnace temperature and slag composition is reflected in the control of thermal regime and slagging regime, specifically including the following aspects:

[0071] 1) The furnace temperature (i.e., the [Ti] content in molten iron) 8-24 hours before the shutdown is controlled at 0.13-0.28%, and the furnace temperature (i.e., the [Ti] content in molten iron) 0-8 hours before the shutdown is controlled at 0.15-0.28%; as the shutdown time approaches, the lower limit of [Ti] content gradually increases;

[0072] 2) Slag composition control: The TiO2 content, binary basicity, and ternary basicity of the slag are consistent with normal production, i.e., the TiO2 content in the slag is controlled at 21.0-23.0%, the binary basicity is controlled at 1.02-1.10, and the ternary basicity is controlled at 1.37-1.47. The control principle of slag composition is as follows: when the TiO2 content in the slag is at the upper limit, the furnace temperature (i.e., the [Ti] content in the molten iron), the binary basicity, and the ternary basicity of the slag are controlled at the lower limit of their respective control ranges; when the TiO2 content in the slag is at the lower limit, the furnace temperature (i.e., the [Ti] content in the molten iron), the binary basicity, and the ternary basicity of the slag are controlled at the upper limit of their respective control ranges; and no other adjustments are made.

[0073] (II) Control of coke cleaning, ore batch weight and coke load before shutdown

[0074] To ensure rapid recovery of the blast furnace after a shutdown, it is necessary to improve the permeability of the burden, loosen the airflow at the edges and center, and further enhance the blast furnace's heat reserve. This ensures good permeability of the burden, reasonable gas flow distribution, sufficient furnace temperature, and good slag and iron flowability during blast furnace recovery. Therefore, it is crucial to control the net coke, ore batch weight, and coke load before the shutdown, specifically including the following aspects:

[0075] The control of coke removal before wind closure is divided into coke removal control for wind closure time ≤ 2 hours and coke removal control for wind closure time 2 to 4 hours (excluding 2 hours). The control of coke removal before short-term wind closure time ≤ 2 hours is as follows:

[0076] Four to six hours before shutting down the wind turbine, add clean coke in 1 to 2 batches, with a total amount of clean coke added before shutting down the wind turbine at 4.5 to 12.0 kg / m³. 3 • Furnace capacity control: the longer the shutdown time, the more the total amount of clean coke added is controlled at the upper limit, and vice versa.

[0077] For short-term wind shutdowns of 2-4 hours, the control of coke removal before shutdown is as follows: 4-6 hours before shutdown, add coke in 2-3 batches separately, with a total amount of coke added before shutdown of 9.0-18.0 kg / m³. 3 • Furnace capacity control: the longer the shutdown time, the more the total amount of clean coke added is controlled at the upper limit, and vice versa.

[0078] Furthermore, the control of ore batch weight and coke load before ventilation shutdown specifically includes the following aspects:

[0079] (1) Control of ore batch weight and coke load before short-term shutdown with a shutdown time of ≤2 hours: 2 to 5 hours before shutdown, the ore batch weight is reduced by 0 to 3% based on the adjustment before the shutdown, and the coke load is reduced by 0 to 3% based on the adjustment before the shutdown.

[0080] (2) Control of ore batch weight and coke load before short-term ventilation shutdowns of 2 to 4 hours (excluding 2 hours):

[0081] ①The first step of adjustment is to reduce the ore batch weight by 0-3% and the coke load by 0-3% 4-5 hours before the ventilation shutdown.

[0082] ② The second step of adjustment is to reduce the ore batch weight by 0-3% and the coke load by 0-3% 2-3 hours before the shutdown.

[0083] This application also controls the pre-shutdown loading system. For planned short-term shutdowns of 2 hours or less (excluding 2 hours), the loading system will not be adjusted. However, for planned short-term shutdowns of 2 to 4 hours, the loading system needs to be adjusted, starting 2 to 3 hours before the shutdown. This adjustment specifically includes the following aspects:

[0084] (1) The charging system is changed from "4-5 ring charging system for ore" to "3-4 ring charging system for ore", and the coke charging system is also reduced. That is, after the adjustment of the charging system, the number of rings for ore and coke is reduced by 1 ring respectively based on the previous system. For example, the charging system is changed from "5 ring charging system for ore" to "4 ring charging system for ore" or the charging system is changed from "4 ring charging system for ore" to "3 ring charging system for ore".

[0085] (2) The difference between the maximum ore angle and the minimum ore angle on the ore platform should be reduced by 0.5 to 2.0° based on normal production.

[0086] (3) The difference between the outer angle of the fabric matrix, i.e. the difference between the maximum angle of coke and the maximum angle of ore, is controlled at 1.0 to 2.0°; the difference between the inner angle of the fabric matrix, i.e. the difference between the minimum angle of ore and the minimum angle of coke, is controlled at 6.0 to 8.0°; and the angle difference between adjacent fabric angles of ore and coke, excluding the minimum angle of coke, is controlled at 1.5 to 3.0°.

[0087] (4) The total number of rings for ore remains unchanged, while the total number of rings for coke is reduced by 1 to 2 rings based on the previous adjustment. The number of rings at the middle angle of ore is 1 to 2 more than the number of rings at the maximum and minimum angles of ore, and the number of rings at the middle angle of coke is 1 to 3 fewer than the number of rings at the maximum and minimum angles of coke. The number of rings at the maximum and minimum angles of ore and coke is equal. The number of rings for ore and coke at the maximum and minimum feeding angles is 3 to 5, and the number of rings for ore and coke at other angles is 1 to 3.

[0088] (5) The minimum coke feeding angle should be reduced by 0 to 1° from the previous angle, i.e., the control range should be 24.0 to 30.0°.

[0089] This application controls the air supply system before shutdown. After the above-mentioned clean coke, batch rejection and heavy load and adjustment of charging system, the air volume and oxygen enrichment are controlled according to the upper and lower limits of blast furnace pressure difference being 3-8 kPa lower than normal production. At the same time, close attention is paid to airflow changes, furnace temperature and charging are controlled, and air and oxygen are reduced when necessary. Collapse and slippage of materials are strictly prohibited to ensure stable and smooth operation of blast furnace.

[0090] The aforementioned control measures are implemented before the shutdown, and no adjustments are made during the shutdown. Adjustments are also necessary after the shutdown to ensure rapid recovery and proper furnace condition restoration. Specifically, this includes the following aspects:

[0091] (1) Adjustment of the air supply system: Before air supply, the air inlet area of ​​the blast furnace is reduced by 0-12% on the basis of the normal air inlet area. The adjustment is made by adding 0-6 refractory rings inside the tuyeres to increase the wind speed and blast energy in the early stage of air supply recovery to activate the hearth.

[0092] If the material level exceeds 3.0m above the material line during the initial stage of air supply recovery, immediately add 2.0-6.0 kg / m of coke separately. 3 Furnace capacity;

[0093] (2) Pressure differential control during air volume recovery:

[0094] ① When the air volume is less than 50% of the normal air volume, the pressure difference is ≤0.130MPa;

[0095] ② When the air volume is 50-70% of the normal air volume, the pressure difference is ≤0.145MPa;

[0096] ③ When the air volume is 70-90% of the normal air volume, the pressure difference is ≤0.165;

[0097] ④ When the air volume is greater than 90% of the normal air volume, the pressure difference is ≤0.175MPa;

[0098] (3) During the process of restoring the furnace condition after the shutdown and increasing the air volume, the furnace temperature, i.e. the [Ti] content of the molten iron, is controlled at 0.15 to 0.28%; the TiO2 content in the slag is controlled at 21.0 to 23.0%; the binary basicity of the slag is controlled at 1.02 to 1.10; and the ternary basicity of the slag is controlled at 1.37 to 1.47.

[0099] (4) Control of other key process parameters during the air supply process:

[0100] ① In the initial stage of blasting, increase the hot blast pressure to 0.08-0.12 MPa and wait for the furnace charge to drop;

[0101] ② When the feeding is smooth, the pressure difference is within a suitable range, and there is no collapse or uneven feeding, increase the blast furnace air volume by 50-100 m³ / h each time. 3 / min, with an interval of ≥3min between each increase in air volume;

[0102] ③ When the air volume increases to 50-60% of the normal air volume, gradually increase the furnace top pressure to 0.040 MPa. Increase the furnace top pressure after each air increase, with the increase in furnace top pressure based on the increase in air volume of 100 m³ / h. 3 / min, the furnace top pressure is increased by 0.007~0.010MPa accordingly;

[0103] ④ When the air volume increases to more than 50% of the normal level, pulverized coal injection begins;

[0104] ⑤ When the air volume increases to more than 70% of the normal level, the ore batch weight and coke load begin to be gradually increased. For every 200-300 m³ / h increase in air volume, the load increases accordingly. 3 / min, ore batch weight increases by 1.0 to 2.0 t / batch, coke load increases by 0.10 to 0.20; when the air volume reaches more than 90% of normal, ore batch weight and coke load recover to 95% to 100% of normal levels;

[0105] ⑥ When the air volume increases to 75-85% of the normal level, the fabric matrix should be adjusted to the normal loading system;

[0106] ⑦ When the air volume increases to the standard wind speed of 200-260 m / s, remove the refractory ring inside the tuyeres to expand the air intake area, so as to further increase the air volume and activate the furnace hearth.

[0107] In the above recovery method, "normal" refers to the relevant process parameters or processes during the smelting of vanadium-titanium pellets.

[0108] In the above-mentioned recovery method, apart from the above adjustments, other operations before and after the shutdown of the vanadium-titanium pellet mine shall be carried out in accordance with methods known to those skilled in the art, and this application does not impose any special restrictions on them.

[0109] Under the smelting conditions of high-proportion all-vanadium-titanium pellets, short-term shutdowns of ≤4 hours were controlled and implemented using the above method. Results showed that the recovery time after a blast furnace shutdown was 4–8 hours shorter than that after a shutdown in blast furnaces with low-proportion all-vanadium-titanium pellets, saving 25–50% of time and 10–30 tons of coke. This method not only improves efficiency but also reduces costs, and provides a reliable method for blast furnace shutdown operations under high-proportion all-vanadium-titanium pellet smelting conditions.

[0110] To further understand the present invention, the following detailed description of the rapid recovery method for a blast furnace with a high proportion of vanadium-titanium pellets during a planned short-term shutdown of 4 hours, in conjunction with embodiments, is provided by the present invention. The scope of protection of the present invention is not limited by the following embodiments.

[0111] Example

[0112] A blast furnace at a certain plant of Panzhihua Iron and Steel Group has an effective volume of 1750m³. 3 During normal production, the TiO2 content in blast furnace slag is 21.0%–23.0%, and the blast furnace burden consists of 45%–65% vanadium-titanium pellets and the remainder vanadium-titanium sinter. The recovery method for a planned short-term shutdown of 4 hours during normal blast furnace production is as follows:

[0113] A) Control of pre-shutdown heating and slag-forming processes

[0114] A1) The furnace temperature and the [Ti] content of the molten iron should be controlled at 0.13-0.26% for 8-24 hours before the shutdown, and at 0.15-0.26% for 0-8 hours before the shutdown.

[0115] A2) The TiO2 content, binary basicity, and ternary basicity of the slag should remain consistent with normal production: the TiO2 content in the slag should be controlled at 22.0-23.0%, the binary basicity should be controlled at 1.02-1.08, and the ternary basicity should be controlled at 1.37-1.45; the control principle for slag composition is as follows: when the TiO2 content in the slag is at the upper limit, the furnace temperature (i.e., the [Ti] content in the molten iron), the binary basicity, and the ternary basicity of the slag should be controlled at the lower limit of the control range; when the TiO2 content in the slag is at the lower limit, the furnace temperature (i.e., the [Ti] content in the molten iron), the binary basicity, and the ternary basicity of the slag should be controlled at the upper limit of the control range.

[0116] No other adjustments will be made.

[0117] B) Control of coke cleaning, ore batch weight, and coke load before shutdown

[0118] B1) Control of coke cleaning before shutdown: 4-6 hours before shutdown, add coke cleaning in 3 separate batches, with a total amount of coke cleaning added at 15.0-18.0 kg / m³. 3 • Furnace capacity control;

[0119] B2) Control of ore batch weight and coke load before shutdown

[0120] (1) First step of adjustment: 4 to 5 hours before the ventilation shutdown, reduce the ore batch weight by 0 to 2% and the coke load by 0 to 2% based on the previous adjustment.

[0121] (2) The second step of adjustment is to reduce the ore batch weight by 0-2% and the coke load by 0-2% on the basis of the previous adjustment 2-3 hours before the shutdown.

[0122] C) Control of the pre-shutdown loading system

[0123] C1) The charging system has been changed from "4-ring ore charging system" to "3-ring ore charging system". The coke charging system has also been reduced. That is, after the adjustment of the rest-air charging system, the number of rings for ore and coke charging will be reduced by 1 ring respectively from the previous system.

[0124] C2) The difference between the maximum and minimum ore angles of the ore platform should be reduced by 0.5 to 1.5° based on normal production conditions.

[0125] C3) The difference between the outer angles of the fabric matrix, i.e., the difference between the maximum angle of coke and the maximum angle of ore, is controlled within 1.0 to 1.5°; the difference between the inner angles, i.e., the difference between the minimum angle of ore and the minimum angle of coke, is controlled within 6.0 to 7.0°; and the angle difference between adjacent fabric angles of ore and coke, excluding the minimum angle of coke, is controlled within 1.5 to 2.5°.

[0126] C4) The total number of ore rings remains unchanged, while the total number of coke rings is reduced by 1 ring compared to the previous adjustment. The number of rings at the middle angle of ore is 1 more than the number of rings at the maximum and minimum angles of ore, and the number of rings at the middle angle of coke is 1-2 fewer than the number of rings at the maximum and minimum angles of coke. The number of rings at the maximum and minimum angles of ore and coke is equal. The number of rings for ore and coke at the maximum and minimum feeding angles is 3-4 rings, and the number of rings for ore and coke at other angles is 1-3 rings.

[0127] C5) The minimum coke feeding angle should be reduced by 0-1° from the previous angle, with a control range of 25.0-28.0°.

[0128] Table 1 shows an example of the above-mentioned charging system adjustment. In Table 1, X is the minimum coke feeding angle value, which ranges from 25.0 to 28.0°.

[0129] Table 1 Examples of Adjustments to the Pre-Short-Term Wind Shutdown Loading System

[0130]

[0131] D) Control of air supply system before planned short-term wind shutdown

[0132] After adding clean coke, removing batches of heavy load and adjusting the charging system, the control of air volume and oxygen enrichment is based on the upper and lower limits of blast furnace pressure difference being 5-8 kPa lower than normal production.

[0133] At the same time, closely monitor airflow changes, control furnace temperature and material feeding, reduce air and oxygen when necessary, strictly prohibit material collapse and slippage, and ensure stable and smooth operation of the blast furnace.

[0134] E) Planned furnace operation after short-term shutdown

[0135] E1) Adjustment of the air supply system: Before air supply, the air inlet area of ​​the blast furnace is reduced by 6-12% on the basis of the normal air inlet area. The adjustment is made by adding 6 refractory rings inside the tuyeres to increase the wind speed and blast energy in the early stage of air supply recovery to activate the hearth.

[0136] If the material level exceeds 3.0m above the material line during the initial stage of air supply recovery, immediately add 3.0-6.0 kg / m of coke separately. 3 Furnace capacity;

[0137] E2) Differential pressure control during airflow recovery:

[0138] ① When the air volume is less than 50% of the normal air volume, the pressure difference is ≤0.128MPa;

[0139] ② When the air volume is 50-70% of the normal air volume, the pressure difference is ≤0.143MPa;

[0140] ③ When the air volume is 70-90% of the normal air volume, the pressure difference is ≤0.166;

[0141] ④ When the air volume is greater than 90% of the normal air volume, the pressure difference is ≤0.173MPa;

[0142] E3) During the process of restoring the furnace condition after a shutdown and increasing the air volume, the furnace temperature, i.e., the [Ti] content in the molten iron, is controlled at 0.15-0.26%; the TiO2 content in the slag is controlled at 21.5-22.5%; the binary basicity of the slag is controlled at 1.05-1.08; and the ternary basicity of the slag is controlled at 1.39-1.45.

[0143] E4) Control of other key process parameters during the air supply process:

[0144] ① In the initial stage of blasting, increase the hot blast pressure to 0.09-0.12 MPa and wait for the furnace charge to drop;

[0145] ② When the feeding is smooth, the pressure difference is within a suitable range, and there is no collapse or uneven feeding, increase the blast furnace air volume by 50-100 m³ / h each time. 3 / min, with an interval of ≥3min between each increase in air volume;

[0146] ③ When the air volume increases to 50-60% of the normal air volume, gradually increase the furnace top pressure to 0.040 MPa. Increase the furnace top pressure after each air increase, with the increase in furnace top pressure based on the increase in air volume of 100 m³ / h. 3 / min, the furnace top pressure is increased by 0.008~0.010MPa accordingly;

[0147] ④ When the air volume increases to more than 50% of the normal level, pulverized coal injection begins;

[0148] ⑤ When the air volume increases to more than 70% of the normal level, the ore batch weight and coke load begin to be gradually increased. For every 200-300 m³ / h increase in air volume, the load increases accordingly. 3 / min, ore load increases by 1.0 to 1.5 t / batch, coke load increases by 0.10 to 0.15; when the air volume reaches more than 90% of normal, the ore batch weight and coke load recover to 97% to 100% of normal levels;

[0149] ⑥ When the air volume increases to 75-85% of the normal level, the fabric matrix should be adjusted to the normal loading system;

[0150] ⑦ When the air volume increases to the standard wind speed of 210-250 m / s, remove the refractory ring inside the small sleeve of the tuyeres to expand the air intake area, so as to further increase the air volume and activate the furnace hearth;

[0151] Table 2 shows an example of controlling the upper limits of air volume, top pressure, and pressure difference during the blast furnace's planned short-term shutdown of 4 hours.

[0152] Table 2. Upper Limits of Air Volume, Top Pressure, and Pressure Difference During Blast Furnace Planned Short-Term Shutdown of 4 Hours.

[0153]

[0154]

[0155] Under the smelting conditions of high proportion of vanadium-titanium pellets, a certain blast furnace can recover to normal operation in only 8 hours after a short shutdown of 4 hours. This is 8 hours shorter than the recovery time of a blast furnace with low proportion of vanadium-titanium pellets, saving 50% of the time and 30 tons of coke.

[0156] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0157] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for rapid recovery of a high proportion of vanadium-titanium pellet blast furnace plan short-term outage within 4 hours, comprising: A) control of heat system and slagging system before the blast furnace is stopped, B) control of net coke, ore batch weight, and coke load before the blast furnace is stopped, C) control of charging system before the blast furnace is stopped, D) control of blast system before the blast furnace is stopped, and E) blast resuming method after short-term stoppage of the blast furnace; the control of heat system and slagging system before the blast furnace is stopped comprises: A1) the content of [Ti] in molten iron is controlled to be 0.13-0.28wt% 8-24 hours before the blast furnace is stopped, and the content of [Ti] in molten iron is controlled to be 0.15-0.28wt% 0-8 hours before the blast furnace is stopped; A2) the content of TiO2 in slag is controlled to be 21.0-23.0wt%, the binary basicity of slag is 1.02-1.10, and the ternary basicity of slag is 1.37-1.47; the control of net coke, ore batch weight, and coke load before the blast furnace is stopped comprises: B1) for short-term stoppage of the blast furnace with a stoppage time of ≤2 hours, net coke is separately added in 1-2 batches 4-6 hours before the blast furnace is stopped; for short-term stoppage of the blast furnace with a stoppage time of 2-4 hours, net coke is separately added in 2-3 batches 4-6 hours before the blast furnace is stopped; B2) for short-term stoppage of the blast furnace with a stoppage time of ≤2 hours, the ore batch weight is reduced by 0-3% on the basis of the adjusted ore batch weight, and the coke load is reduced by 0-3% on the basis of the adjusted coke load 2-5 hours before the blast furnace is stopped; for short-term stoppage of the blast furnace with a stoppage time of 2-4 hours, the ore batch weight is reduced by 0-3% on the basis of the adjusted ore batch weight, and the coke load is reduced by 0-3% on the basis of the adjusted coke load 4-5 hours before the blast furnace is stopped; the ore batch weight is further reduced by 0-3% on the basis of the adjusted ore batch weight, and the coke load is further reduced by 0-3% on the basis of the adjusted coke load 2-3 hours before the blast furnace is stopped; the control of charging system before the blast furnace is stopped, the stoppage time of the blast furnace being 2-4 hours, comprises: C1) the number of ore and coke charging rings is reduced by 1 ring on the basis of the adjusted number of ore and coke charging rings; C2) the difference between the maximum ore angle and the minimum ore angle is reduced by 0.5-2.0° on the basis of the adjusted difference between the maximum ore angle and the minimum ore angle; C3) the difference between the maximum coke angle and the maximum ore angle is 1.0-2.0°, the difference between the maximum ore angle and the minimum coke angle is 6.0-8.0°, and the angle difference between adjacent ore and coke charging angles is 1.5-3.0°; C4) the total number of ore charging rings is unchanged, the total number of coke charging rings is reduced by 1-2 rings on the basis of the adjusted total number of coke charging rings, the number of ore intermediate angle rings is 1-2 more than the number of ore maximum and minimum angle rings, the number of coke intermediate angle rings is 1-3 less than the number of coke maximum and minimum angle rings, and the number of ore maximum and minimum angle rings is equal to the number of coke maximum and minimum angle rings; the number of ore and coke charging rings at the maximum and minimum charging angles is 3-5, and the number of ore and coke charging rings at the remaining angles is 1-3; C5) the minimum coke charging angle is controlled to be 24.0-30.0°; the control of blast system before the blast furnace is stopped comprises: D1) the control of blast volume and oxygen enrichment volume is based on the upper and lower limit values of blast furnace pressure difference being 3-8kPa lower than the normal production; the blast resuming method after short-term stoppage of the blast furnace comprises: E1) before blast resuming, the blast inlet area of the blast furnace is reduced by 1-12% on the basis of the normal blast inlet area; E2) the pressure difference control during the air volume recovery process: when the air volume is less than 50% of the normal air volume, the pressure difference is less than or equal to 0.130 MPa; when the air volume is 50-70% of the normal air volume, the pressure difference is less than or equal to 0.145 MPa; when the air volume is 70-90% of the normal air volume, the pressure difference is less than or equal to 0.165 MPa; when the air volume is more than 90% of the normal air volume, the pressure difference is less than or equal to 0.175 MPa; E3) during the road condition recovery process and the air volume increasing process after the blast furnace is stopped, the [Ti] content of the molten iron is controlled to be 0.15-0.28 wt%, the TiO2 content in the slag is controlled to be 21.0-23.0%, the binary basicity of the slag is controlled to be 1.02-1.10, and the ternary basicity of the slag is controlled to be 1.37-1.

47.

2. The recovery method according to claim 1, characterized by, The burden structure of the blast furnace comprises: 45-65 wt% of the total vanadium-titanium pellet, and the rest is vanadium-titanium sinter.

3. The recovery method according to claim 1, characterized by, In step A2), when the TiO2 content in the slag is controlled to be the upper limit, the [Ti] content of the molten iron, the binary basicity of the slag, and the ternary basicity of the slag are controlled to be the lower limit; and when the TiO2 content in the slag is controlled to be the lower limit, the [Ti] content of the molten iron, the binary basicity of the slag, and the ternary basicity of the slag are controlled to be the upper limit.

4. The recovery method of claim 1, wherein In step B1), for the short-term stoppage with a stoppage time of less than or equal to 2 h, the control of the net coke added is specifically as follows: 4-6 hours before cooling, add 1-2 batches of clean coke separately, the total amount of clean coke added before cooling is 4.5-12.0 kg / m 3 • Furnace capacity control.

5. The recovery method according to claim 4, characterized by, In step B1), for the short-term stoppage with a stoppage time of 2-4 h, the control of the net coke added is specifically as follows: 4-6 hours before the cooling, add 2-3 batches of coke separately, the total amount of coke added before the cooling is 9.0-18.0 kg / m 3 • Furnace volume control.

6. The recovery method of claim 1, wherein, The stoppage time is less than or equal to 2 h, and the charging system before the stoppage is not adjusted.

7. The recovery method of claim 1, wherein The air supply recovery method after the short-term idle period, the collapse and slide material exceeds the material line by 3.0 m or more before the air supply recovery early stage, and 2.0-6.0 kg / m of coke is added alone 3 · Furnace capacity.

8. The recovery method of claim 1, wherein, The step E3) further comprises: The hot blast pressure is increased to 0.08-0.12 MPa in the early stage of the blast, and the burden in the blast furnace is allowed to drop; When the burden drops smoothly, the pressure difference is in the appropriate range, and there is no phenomenon of slumping and partial burden, the blast volume of the blast furnace is increased, each time the blast volume is increased by 50-100 m3 / min, and the time interval for each increase of the blast volume is greater than or equal to 3 min; When the air volume is increased to 50-60% of the normal air volume, the furnace top pressure is gradually increased to 0.040 MPa, and after each air increase, the furnace top pressure is increased, and the furnace top pressure is increased by 0.007-0.010 MPa for each 100 m 3 / min increase in air volume. When the blast volume is increased to more than 50% of the normal blast volume, coal injection is started; When the blast volume is increased to more than 70% of the normal blast volume, the ore batch weight and the coke load start to be gradually increased, and when the blast volume is increased by 200-300 m3 / min, the ore is increased by 1.0-2.0 t / batch, and the coke load is increased by 0.10-0.20; When the blast volume reaches more than 90% of the normal blast volume, the ore batch weight and the coke load are restored to 95-100% of the normal level; When the blast volume is increased to 75-85% of the normal blast volume, the charging matrix is adjusted to the normal charging system.

9. The recovery method according to claim 8, characterized by, In the step after the step E3): When the blast volume is increased to a standard blast speed of 200-260 m / s, the refractory mud in the tuyere small sleeve or the refractory ring in the small sleeve is removed until the blast volume is restored to the normal level.

10. The recovery method according to any one of claims 1 to 9, characterized in that, The blast furnace has a furnace volume of 1200-2200 m 3 .

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