Method for reducing temperature of brick lining in iron notch area of blast furnace hearth

Abstract

The invention aims to provide a method for reducing the temperature of a brick lining in an iron notch area of a blast furnace hearth, and provides a method for reducing the temperature of the brick lining in the iron notch area of the blast furnace by adjusting the tapping time sequence to reduce the temperature and the iron flux of the iron notch by 10-15%, restoring the depth of the iron notch to a normal level by increasing the mud ramming amount of the iron notch in two sections by 5-20%, controlling the molten iron [Si] to be 0.50-0.60%, controlling the molten iron [S] to be 0.018-0.025% and the like according to the condition that the temperature of the brick lining in the iron notch area of the blast furnace abnormally rises. Under the conditions of keeping the furnace condition stable and smooth and reducing the yield loss, a mud drum and a slag iron condensation layer in an iron notch area are repaired, the temperature of a brick lining in the iron notch area is reduced, safety risks are eliminated, and the service life of a blast furnace is prolonged.

Description

Technical Field

[0001] This invention relates to blast furnace ironmaking technology, and more specifically to a method for reducing the temperature of the brick lining in the taphole area of ​​a blast furnace hearth. Background Technology

[0002] The blast furnace hearth serves to support the blast furnace body and contain and discharge molten iron. The hearth's structure typically consists of refractory materials, a cooling system, and supporting structures. The refractory material is the core of the hearth, usually made of carbon bricks or ceramic materials to withstand the erosion and thermal stress of the high-temperature molten material. The cooling system uses water-cooled walls to cool the brick lining inside the hearth, preventing damage due to excessive temperature.

[0003] The taphole lining of the hearth is subjected to the scouring and thermal stress of high-temperature molten iron over a long period of time. When the brick lining deteriorates, peels off, or even fails, the thickness of the brick lining decreases accordingly, the heat flux increases, and the temperature of the thermocouples embedded in the brick lining rises accordingly. Therefore, the temperature of the thermocouples in the taphole area of ​​the hearth can reflect the working condition of the hearth brick lining in the taphole area.

[0004] Lowering the temperature of the refractory lining in the taphole area is a crucial aspect of blast furnace operation. Excessive taphole temperature indicates refractory material corrosion, shortening the taphole's lifespan and potentially leading to safety accidents. Therefore, implementing process measures to reduce the refractory lining temperature when it rises in the taphole area is essential for ensuring the safe and stable operation of the blast furnace, extending its lifespan, and reducing production costs. This is one of the significant technical challenges in blast furnace operation.

[0005] This method aims to provide a way to reduce the temperature of the brick lining in the blast furnace taphole area. It proposes a solution to the abnormally high temperature of the brick lining in the taphole area by adjusting parameters such as the tapping time sequence, the amount of mud removed from the taphole, and the [Si] and [S] content of the molten iron. This method aims to repair the mud bag and slag-iron solidification layer in the taphole area while maintaining stable furnace operation and reducing production losses, thereby reducing the temperature of the brick lining in the taphole area, eliminating safety risks, and extending the service life of the blast furnace. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing a method for reducing the temperature of the brick lining in the taphole area of ​​a blast furnace hearth.

[0007] The objective of this invention is achieved as follows: A method for reducing the brick lining temperature in the taphole area of ​​a blast furnace hearth, comprising the following steps: Step 1: Adjusting the tapping time and sequence to reduce the tapping time in high-temperature areas: For a double-tap blast furnace, the tapping interval is 20-25 minutes. After the thermocouple temperature in the No. 1 taphole area rises above the safety control warning value, the No. 1 taphole is blocked. The No. 2 taphole is opened 25-35 minutes after the No. 1 taphole is blocked. After the No. 2 taphole is blocked, the No. 1 taphole is opened at the same time as the No. 2 taphole. After the taphole is blocked, it should be opened 10-20 minutes later. For blast furnaces with more than three tapholes, the tapping should be overlapped by 10-30 minutes, meaning the next taphole should be opened 10-30 minutes before the previous taphole is planned to be blocked. In this case, after taphole #1 is opened, the opening time of the next taphole should be 10-15 minutes earlier than the average tapping time of the five days before the hearth brick lining temperature rises, minus the planned overlap time of 10-30 minutes. The blocking time of taphole #1 should be correspondingly 10-15 minutes earlier than the average tapping time of the five days before the hearth brick lining temperature rises. When tapping iron again at tap #1, the opening time should be 10-15 minutes earlier than the average tapping time of the five days prior to the rise in the hearth brick lining temperature. For other tapping cycles, the tapping time should be adjusted to the average tapping time of the five days prior to the rise in the hearth brick lining temperature. Based on the above adjustment of tapping time, the diameter of the drill bit at tap #1 should be reduced by 5mm, i.e., the normal drill bit diameter of 50-55mm should be adjusted to 45-50mm. Step 2: Increase the amount of mud removal in stages to maintain the normal tapping depth: When the thermocouple temperature in the area of ​​tap #1 rises above the safety limit... When the taphole depth is more than 5% lower than the average value of the five days before the temperature of the hearth brick lining rises, increase the amount of mud by 5% to 10% based on the average amount of mud applied in the five days before the temperature of the hearth brick lining rises, and continue for 4 to 5 heats. If the taphole depth does not recover, continue to increase the amount of mud by 15% to 20% based on the average value of the five days before the temperature of the hearth brick lining rises, and continue for 4 to 5 heats. Then restore the increased amount of mud to 5% to 10% of the average value of the five days before the temperature of the hearth brick lining rises. Step 3: Adjust the fuel ratio and control Si and S.

[0008] In step three, Si and S are controlled: while taking steps one and two, the Si content of the molten iron is controlled to 0.50%~0.60% and the S content to 0.018%~0.025% by adjusting the fuel ratio, heat regime, and slag formation regime.

[0009] The beneficial effects of this invention are as follows: Using this method in the 1800m³ blast furnace at Taiyuan Iron & Steel Plant, the temperature control effect is good after a rapid rise in the brick lining temperature in the north taphole area. The thermocouple temperature at 0° elevation (8m) is controlled to be less than 300℃, and at 18° elevation (9m) it is less than 290℃. The current generation of the 1800m³ blast furnace at Taiyuan Iron & Steel Plant has been in operation for 18 years, achieving a unit furnace capacity iron output of 16,300 t / m³, ranking among the top blast furnaces of its class in China, achieving safe, efficient, and long-term operation. Since 2024, four instances of abnormal temperature rise in the hearth taphole area have been successfully handled. Based on a 24-hour shutdown for cooling each time, with a production loss of 6,000 t and an increase in coke consumption of 120 t per shutdown, the economic benefit is 4.36 million yuan.

[0010] This technology can effectively control the temperature of the brick lining in the taphole area of ​​the hearth, extend the service life of the blast furnace, and has strong promotional value. Detailed Implementation

[0011] This invention employs the following basic technical concept: The temperature rise in the blast furnace hearth taphole area brick lining is usually caused by improper tapping time, shallow taphole depth, and erosion of the solidified protective layer, leading to direct contact between the carbon bricks and molten iron, or even erosion itself. Increased heat flow intensity causes the brick lining temperature to rise. To address the threat to safe production caused by the elevated temperature of the blast furnace hearth taphole area brick lining, this invention gradually reduces the brick lining temperature in this area and extends the blast furnace's service life by adjusting the number and timing of tapping, adjusting the amount of sludge removal to increase taphole depth and reduce molten iron flow erosion, and adjusting the [Si] and [S] content of the molten iron to promote the formation of a new slag shell solidification protective layer.

[0012] A method for reducing the temperature of the brick lining in the taphole area of ​​a blast furnace is proposed. This method addresses the abnormally high temperature of the brick lining in the taphole area by adjusting the tapping time sequence to reduce the iron flow rate at the high-temperature taphole by 10%–15%, increasing the amount of mud removed from the taphole in two stages by 5%–20% to restore the taphole depth to normal levels, and controlling the [Si] content of the molten iron to 0.50%–0.60% and [S] content to 0.018%–0.025%. While maintaining stable furnace operation and reducing production losses, this method repairs the mud bag and slag-iron solidification layer in the taphole area, reduces the temperature of the brick lining in the taphole area, eliminates safety risks, and extends the service life of the blast furnace. Specifically: 1. For blast furnaces with dual tapholes, the tapping interval is advanced by 5–10 minutes; for blast furnaces with multiple tapholes, the overlapping tapping time is advanced by 10–15 minutes. Simultaneously, the taphole drill diameter is reduced by 5 mm to reduce the iron flow rate at the high-temperature taphole by 10%–15%. Adjust the tapping time and sequence to reduce the tapping time in high-temperature areas: For blast furnaces with two tapholes, the tapping interval is 20-25 minutes. If the thermocouple temperature in the No. 1 taphole area rises above the safety control warning value (the specific value is determined according to the safety production technical regulations of each blast furnace), after the No. 1 taphole is blocked, the opening time of the No. 2 taphole is delayed by 5-10 minutes from 20-25 minutes after the No. 1 taphole is blocked to 25-35 minutes. After the No. 2 taphole is blocked, the opening time of the No. 1 taphole is advanced by 5-10 minutes from 20-25 minutes after the No. 2 taphole is blocked to 10-20 minutes. For blast furnaces with three or more tapholes, tapping should be overlapped by 10-30 minutes, i.e., the next tapping should be done 10-30 minutes before the previous tapping is planned to be blocked. When the taphole is opened, the opening time of the next taphole should be 10-15 minutes earlier than the average tapping time of the five days before the temperature of the hearth brick lining rises, minus the planned overlap time (10-30 minutes). The taphole blocking time of #1 should be 10-15 minutes earlier than the average tapping time of the five days before the temperature of the hearth brick lining rises. The opening time of #1 taphole when tapping again should be 10-15 minutes earlier than the average tapping time of the five days before the temperature of the hearth brick lining rises. The tapholes of other furnaces should be opened and blocked according to the average tapping time of the five days before the temperature of the hearth brick lining rises. Based on the above adjustment of tapping time, the diameter of the drill bit of #1 taphole should be reduced by 5mm, that is, the normal drill bit diameter of 50-55mm should be adjusted to 45-50mm.

[0013] 2. Increase the amount of mud in stages to maintain normal taphole depth: When the thermocouple temperature in the No. 1 taphole area rises above the safety control warning value, and the taphole depth is more than 5% lower than the average of the five days before the rise in hearth brick lining temperature, increase the amount of mud at the high-temperature taphole by 5% to 10% based on the average amount of mud applied in the five days before the rise in hearth brick lining temperature, and continue for 4 to 5 heats. If the taphole depth does not recover, continue to increase the amount of mud applied by 15% to 20% based on the average amount of mud applied in the five days before the rise in hearth brick lining temperature, and continue for 4 to 5 heats. Then restore the increased amount of mud to 5% to 10% of the average amount of mud applied in the five days before the rise in hearth brick lining temperature.

[0014] While adopting steps 1 and 2, the [Si] content of molten iron is controlled to 0.50%~0.60% and [S] to 0.018%~0.025% by adjusting the fuel ratio and heat regime and slag formation regime.

[0015] The specific technical solution of this invention is as follows: 1. Adjust the tapping time and sequence to reduce the tapping time of the tapping tap in the high-temperature area. Generally, the tapping time of a single tap in a blast furnace is 2.0~2.5 hours. When the temperature of a certain tap area rises (taking the temperature of tap #1 as an example), the tapping time of that tap is shortened without reducing the number of tapping furnaces. The specific measures are as follows: For a double-tap blast furnace, the tapping interval (from the previous tapping tap being blocked to the opening of the next tap) is generally 20~25 minutes. After the temperature of the tap #1 area rises and tap #1 is blocked, the opening time of tap #2 is delayed by 5~10 minutes, and the opening time of tap #1 is advanced by 5~10 minutes after tap #2 is blocked.

[0016] For blast furnaces with three or more tapholes, overlapping tapping is generally implemented (the next taphole opens before the previous one is closed), lasting 10-30 minutes. In this case, after taphole #1 opens, the opening time of the next taphole is 10-15 minutes earlier than the average tapping time of the five days before the hearth lining temperature rises, and the closing time of taphole #1 is correspondingly advanced by 10-15 minutes. The opening time of taphole #1 when tapping again is 10-15 minutes earlier than the average tapping time of the five days before the hearth lining temperature rises. For other taphole runs, the opening and closing times are organized according to the average tapping time of the five days before the hearth lining temperature rises.

[0017] Based on the above-mentioned adjustment of the tapping time, the diameter of the No. 1 iron tapping drill bit is reduced by 5mm, that is, the normal drill bit diameter is 50~55mm, which is adjusted to 45~50mm, in order to slow down the tapping speed.

[0018] By adjusting the tapping time and the drill bit diameter, the iron flow rate can be reduced by 10% to 15% without reducing the number of tapping furnaces at tap #1. This effectively reduces the scouring and erosion of the area by molten iron, which is conducive to the formation of a new protective layer and lowers the temperature in the area.

[0019] 2. Increase the amount of slurry applied in stages to maintain normal taphole depth. When the temperature of the taphole lining rises, it is often accompanied by a decrease in taphole depth, significantly lower than normal production levels. In this case, the amount of slurry applied should be increased in stages to restore the taphole depth to a normal level and maintain it until the lining temperature returns to normal. Taking the temperature rise in the No. 1 taphole area of ​​a blast furnace as an example, the specific measures are as follows: When the temperature of the No. 1 taphole rises and the taphole depth is more than 5% lower than the average of the five days before the rise in the hearth lining temperature, increase the amount of slurry applied by 5% to 10% based on the average amount applied in the five days before the rise in the hearth lining temperature, continuing for 4 to 5 heats. If the taphole depth does not recover, continue to increase the amount of slurry applied by 15% to 20% based on the average amount applied in the five days before the rise in the hearth lining temperature, continuing for 4 to 5 heats, and then restore the increased amount of slurry to 5% to 10% of the average amount applied in the five days before the rise in the hearth lining temperature. Taking a 1800m³ blast furnace as an example, the average amount of mud applied in the five days before the temperature of the No. 1 taphole furnace brick lining rises is 110L, and the taphole depth is 2600~2800mm. If the taphole depth is less than 2500mm, the amount of mud applied to the taphole is increased to 120L for 4~5 furnaces. If the taphole depth recovers to above 2600mm, the amount of mud applied is increased to 130L for 4~5 furnaces, then reduced back to 120L, until the taphole depth recovers to above 2600mm.

[0020] 3. Adjust the fuel ratio to control [Si] and [S], maintain basic fluidity, and reduce erosion of the brick lining.

[0021] While taking steps 1 and 2, the [Si] of the molten iron is controlled to 0.50%~0.60% and [S] to 0.018%~0.025% by adjusting the fuel ratio, heat regime, and slag formation regime. While maintaining the temperature and fluidity of the molten iron to meet the normal production requirements, the scouring and erosion of the newly formed mud bale and slag-iron solidification protective layer by the molten iron is reduced, the heat flow intensity in the high-temperature area is reduced, and thus the temperature of the furnace hearth brick lining is reduced.

[0022] 4. After adopting steps 1 to 3, the rising trend of the brick lining temperature in the blast furnace taphole area will be alleviated. After 2 to 3 days of operation, the temperature will show a downward trend, avoiding the aggravation of the erosion of the hearth brick lining, thereby improving the safety of blast furnace operation. Example 1

[0023] This method has been successfully applied in the 1800m³ blast furnace of Taiyuan Iron & Steel Group. Taking the temperature rise of the 9.276m 18° direction thermocouple in the North Iron Mound area from July 24th to July 27th, 2024 as an example, the specific implementation plan is as follows: On July 24th, 2024, during the day shift, the temperature of the hot surface thermocouple in the 9.276m 18° direction in the North Iron Mound area rose from 245℃ to 315℃. On that day, there were two heats at the North Iron Mound with a depth below 2500mm, and [Si] was below 0.35% for multiple consecutive heats.

[0024] Measure 1: After the south iron tap is blocked, the time interval between opening the north iron tap is reduced from 25 minutes to 15 minutes, the drill bit is changed from 47.5 mm to 45 mm, and the iron tapping time of a single furnace at the north iron tap is shortened from 1 hour and 50 minutes to 1 hour and 30 minutes.

[0025] Measure 2: The amount of mud poured at the north iron taphole was increased from 115L to 125L, and after 5 heats, the taphole depth was increased from 2500mm to 2700mm.

[0026] Measure 3: Increase the fuel ratio by 10 kg / t to rapidly increase the molten iron [Si] to 0.55%, while simultaneously increasing the slag basicity from 1.18 to 1.22 and reducing the molten iron [S] from 0.030% to 0.020%.

[0027] After the above measures were taken, the temperature of the hot surface thermocouple at 9.276m 18° direction began to drop during the night shift on July 26, and the temperature recovered to below 250℃ during the day shift on July 27. Example 2

[0028] Taking the temperature rise of the thermocouple at 8.116m 0° in the Beitiekou area from December 15th to December 18th, 2024 as an example, the specific implementation plan is as follows: On the night shift of December 15th, 2024, the temperature of the hot surface thermocouple at 8.116m 0° in the Beitiekou area rose from 272℃ to 338℃. The [Si] content was below 0.35% for several consecutive furnace runs the previous day.

[0029] Measure 1: After the south iron tap is blocked, the time interval between opening the north iron tap is reduced from 23 minutes to 15 minutes, the drill bit is changed from 47.5 mm to 45 mm, and the iron tapping time of a single furnace at the north iron tap is shortened from 1 hour and 45 minutes to 1 hour and 30 minutes.

[0030] Measure 2: The amount of mud poured at the north iron taphole was increased from 110L to 120L, and after 4 heats, the taphole depth was increased from 2500mm to 2700mm.

[0031] Measure 3: Increase the fuel ratio by 8 kg / t to rapidly increase the molten iron [Si] to 0.50%, while simultaneously increasing the slag basicity from 1.18 to 1.22 and reducing the molten iron [S] from 0.028% to 0.020%.

[0032] After the above measures were taken, the temperature of the hot surface thermocouple at 8.116m0° on the middle shift began to drop on December 17, and the temperature recovered to below 270℃ on the day shift on December 18.

[0033] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for reducing the temperature of the brick lining in the taphole area of ​​a blast furnace hearth, characterized in that: Includes the following steps: Step 1: Adjust the tapping time and sequence to reduce the tapping time in high-temperature areas: For blast furnaces with two tapholes, the tapping interval is 20-25 minutes. If the thermocouple temperature in the No. 1 taphole area rises above the safety control warning value, after the No. 1 taphole is blocked, the No. 2 taphole opens 25-35 minutes after the No. 1 taphole is blocked, and after the No. 2 taphole is blocked, the No. 1 taphole opens 10-20 minutes after the No. 2 taphole is blocked. For blast furnaces with three or more tapholes, tapping should be overlapped by 10-30 minutes, meaning the next taphole opens 10-30 minutes before the previous taphole is planned to be blocked. In this case, after the No. 1 taphole opens, the next taphole opens at the time indicated by the furnace hearth bricks. Based on the average tapping time of the five days prior to the rise in lining temperature, minus the planned overlap time of 10-30 minutes, advance the tapping time by 10-15 minutes. Correspondingly, the tapping time of tap #1 should be advanced by 10-15 minutes based on the average tapping time of the five days prior to the rise in lining temperature. The tapping opening time of tap #1 when tapping again should be advanced by 10-15 minutes based on the average tapping time of the five days prior to the rise in lining temperature. For other tapping cycles, the tapping opening and closing times should be based on the average tapping time of the five days prior to the rise in lining temperature. Based on the above adjustments to tapping time, the diameter of the drill bit at tap #1 should be reduced by 5mm, i.e., the normal drill bit diameter of 50-55mm should be adjusted to 45-50mm. Step 2: Increase the amount of mud in stages to maintain normal taphole depth: When the thermocouple temperature in the No. 1 taphole area rises above the safety control warning value, and the taphole depth is more than 5% lower than the average of the five days before the rise in hearth brick lining temperature, increase the amount of mud by 5% to 10% based on the average amount of mud applied in the five days before the rise in hearth brick lining temperature, and continue for 4 to 5 heats. If the taphole depth does not recover, continue to increase the amount of mud by 15% to 20% based on the average of the five days before the rise in hearth brick lining temperature, and continue for 4 to 5 heats. Then restore the increased amount of mud to 5% to 10% of the average of the five days before the rise in hearth brick lining temperature. Step 3: Adjust the fuel ratio to control Si and S.

2. A method for reducing the temperature of the brick lining in the taphole area of ​​a blast furnace hearth, characterized in that: In step three, Si and S are controlled: while taking steps one and two, the Si content of the molten iron is controlled to 0.50%~0.60% and the S content to 0.018%~0.025% by adjusting the fuel ratio, heat regime, and slag formation regime.